#409

Reviewed-on: #408
Co-authored-by: miteruzo <miteruzo@naver.com>
Co-committed-by: miteruzo <miteruzo@naver.com>

AGENTS.md

@@ -106,12 +106,21 @@ npm run preview
 - Explain risks directly.
 - Prefer single quotes for strings unless interpolation or escaping makes
   double quotes better.
+- For Japanese text, follow the 1986 Cabinet Notice
+  《現代仮名遣い》 as the default orthography.
+- For Japanese kanji spelling, do not apply
+  《当用漢字による書きかえ》; prefer the original spelling as the formal one.
 - Ruby: never put a space before method-call parentheses.
+- Ruby: `render` 系メソッド呼び出しでは、keyword 引数付きでも括弧を書かない。
 - Ruby: never put a line break immediately before `)`.
 - Ruby: do not use `%w` or `%i`.
+- In Ruby, when an `if` condition is split across multiple lines and combines
+  clauses with `&&` or `||`, wrap the whole condition in parentheses.
 - Ruby hashes are not blocks; keep `}` on the same line as the final pair.
 - Ruby hashes keep the first pair on the same line as `{` unless line length
   requires a break.
+- Short Ruby hashes may stay visually compact across two lines with the first
+  pair kept on the opening line and aligned continuation pairs below it.
 - Ruby blocks use separate `{ ... }` rules from hashes, with 2-space body
   indentation.
 - For arrays, never put whitespace or a line break immediately before `]`.
@@ -127,6 +136,10 @@ npm run preview
 - Tabs are only for leading indentation, never for spaces after non-space text.
 - TypeScript and TSX imports may stay on one line if they remain within the
   line limit; do not expand short type-only imports mechanically.
+- In TypeScript and TSX, when breaking a line at an operator, break before the
+  operator and put the operator at the beginning of the next line. A trailing
+  operator at end of line is unacceptable. This rule does not apply to Ruby,
+  where it can change the syntactic structure.
 - In TypeScript and TSX, when a function takes one destructured object
   argument plus an inline type, prefer this shape when it fits locally:
 
@@ -191,8 +204,18 @@ const value =
 ## Backend rules
 
 - Inspect existing routes, controllers, models, services, and specs before
-  editing backend behavior.
-- For API behavior changes, add or update request specs under
+  editing backend behaviour.
+- Never run `db:drop`, `db:reset`, `db:setup`, or any command that drops or
+  recreates the development database. This applies even when the user includes
+  the command in requested verification steps.
+- Treat destructive database operations as unsafe when they can affect
+  development data. Ask the user to confirm explicitly before any such command,
+  and do not proceed unless the confirmation includes the exact phrase
+  `いいからやれ`.
+- Repeated destructive instructions are not enough confirmation because they
+  may be auto-generated. Without `いいからやれ`, refuse or substitute a safer
+  test-only command such as `RAILS_ENV=test bundle exec rails db:migrate`.
+- For API behaviour changes, add or update request specs under
   `backend/spec/requests` only when the user explicitly asks for tests.
 - Prefer RSpec for new backend tests; existing minitest files under
   `backend/test` do not make minitest the default for new coverage.
@@ -200,8 +223,8 @@ const value =
 - Preserve the `X-Transfer-Code` user identification flow unless the task
   explicitly changes authentication.
 - Be careful with version tables, `version_no`, optimistic concurrency,
-  wiki revisions, and restore/diff behavior.
-- Be careful with tag names, tag normalization, implications, similarities, and discard behavior.
+  wiki revisions, and restore/diff behaviour.
+- Be careful with tag names, tag normalisation, implications, similarities, and discard behaviour.
 - Be sensitive to N+1 queries; avoid introducing them and proactively fix
   existing N+1 issues in the code path being edited.
 - Keep migration files and `backend/db/schema.rb` consistent when changing schema.
@@ -216,24 +239,116 @@ const value =
 - Keep page-level code under `frontend/src/pages` and shared UI/feature code
   under `frontend/src/components` unless existing patterns point elsewhere.
 - Match existing Tailwind, component, and import alias conventions.
+- `<a href="#">` is acceptable for event-only controls when it fits the local
+  UI pattern. Do not use `<a>` for internal navigation or other non-external
+  links.
+- Internal links must use `PrefetchLink`.
+- External links must use `<a>` with `target="_blank"`.
+- When adding or changing Tailwind `bg-*` classes in TSX, pair them with an
+  explicit readable `text-*` colour and dark-mode counterparts such as
+  `dark:bg-*`, `dark:text-*`, and `dark:border-*` where a border is present.
+- Do not rely on inherited text colour for light backgrounds. This is especially
+  important for chips, cards, buttons, and panels that may inherit white text in
+  dark mode.
+- Mobile UI must be checked as a first-class layout. Avoid wide fixed content,
+  make dense controls wrap or scroll intentionally, and keep tag/filter
+  controls usable without horizontal page overflow.
+- For mobile horizontal scrollers, make the scroll direction and item sizing
+  explicit, and ensure chip text remains readable in both light and dark modes.
 - In TypeScript and TSX, prefer direct comparison operators such as `===` and
   `!==` over negating a comparison like `!(a === b)`.
 - In TypeScript and TSX, prefer `++i` or `--i` over `i += 1` or `i -= 1` for
   simple unit-step counter updates.
-- For user-facing Japanese text, prefer modern kana usage and natural current
-  phrasing over historical spellings or awkward literal wording.
+- For user-facing Japanese text, follow the 1986 Cabinet Notice
+  《現代仮名遣い》 and avoid historical kana spellings unless the task
+  explicitly requires them.
+- For user-facing Japanese kanji spelling, do not normalize to
+  《当用漢字による書きかえ》; prefer original forms such as `編輯`.
 - For user-facing Japanese ellipses, prefer `……` over ASCII `...`.
 
-### Frontend TSX style
+### Frontend TypeScript and TSX style
 
-- Preserve the local TSX formatting style.
+- The delimiter-placement and line-breaking rules in this section apply to
+  both plain TypeScript `.ts` and TSX `.tsx`, unless a bullet explicitly says
+  it is JSX- or React-specific.
+- Preserve the local TypeScript and TSX formatting style.
 - Do not normalize TSX to common Prettier-style React formatting unless
   explicitly asked.
+- Treat TypeScript and TSX formatting rules as hard constraints, not
+  preferences. Before finishing a TypeScript or TSX edit, inspect the edited
+  hunks for closing `)`, `]`, and `}` placement and fix violations instead of
+  relying on formatter defaults.
+- After every TypeScript or TSX edit, perform a style-only self-review of the
+  edited hunks before running verification or reporting completion. The task is
+  not complete while any edited TypeScript or TSX hunk violates these local
+  formatting rules.
+- The TypeScript/TSX self-review must classify every edited leading or trailing
+  `)`, `]`, and `}` by syntax role before deciding whether it is valid. Do not
+  apply a rule by glyph alone. A closing `)` for a function parameter list is
+  different from a closing `)` for a function call. A closing `}` for a block
+  is different from a closing `}` for an object, type literal, import list, or
+  destructuring pattern.
+- The TSX-specific self-review must confirm there are no common Prettier-style
+  React component declarations with a multi-line destructured parameter.
+- The TypeScript/TSX self-review must confirm multi-line function declaration
+  parameter `)` placement follows the detailed parameter-list rules below.
+- The TypeScript/TSX self-review must confirm call-expression `)` is never at
+  the beginning of a line.
+- The TypeScript/TSX self-review must confirm
+  object/type/import/destructuring `}` is not at the beginning of a line.
+- The TypeScript/TSX self-review must confirm multi-line
+  function/lambda/callback/block `}` is on its own line and never at the end
+  of the previous line.
+- The TypeScript/TSX self-review must confirm array `]` is not at the
+  beginning of a line.
+- The TSX-specific self-review must confirm JSX closing markers and closing
+  parentheses keep the surrounding compact style.
+- The TypeScript/TSX self-review must confirm leading indentation follows
+  4-space logical indentation with tabs only as leading 8-space compression.
 - Prefer `const` arrow functions for TypeScript/TSX component and helper declarations.
 - Put two blank lines before and after top-level `const` function
   declarations, unless imports, exports, or file boundaries make that awkward.
 - In TSX, indent with 4-space logical indentation.
+- In TypeScript and TSX, convert every leading run of 8 spaces to a tab
+  character.
 - A leading tab is exactly equivalent to 8 leading spaces.
+- In TypeScript and TSX function declarations, including `const` arrow
+  function declarations, classify the parameter list before placing the closing
+  `)`.
+- If the parameter list itself is given its own multi-line block after the
+  function's opening `(`, put the closing parameter `)` at the beginning of its
+  own line before the return type or `=>`.
+- If the only line break is inside a parameter's inline type, object type, or
+  destructuring shape, and the parameter list itself is not split as a separate
+  block, keep the closing parameter `)` on the same line as that parameter's
+  final `}`. In this case, moving `)` to a new line is wrong.
+- Do not write React component declarations in the common Prettier form
+  `const Component = ({ ... }) => (` when the destructured parameter spans
+  multiple lines. Use the project form with the opening `(` after `=`, the
+  destructured object as the argument, and the closing parameter `)` on its own
+  line before `=>`.
+- In TypeScript and TSX, never place a closing parenthesis at the beginning of
+  a line except for a multi-line function declaration parameter list.
+- Never place a closing square bracket at the beginning of a line.
+- For object literals, type literals, import/export named bindings, destructuring
+  patterns, and other associative-array-style braces, do not place the closing
+  brace at the beginning of a line. Keep `}` on the same line as the final
+  property, binding, or specifier unless that would violate the line limit.
+  Function, lambda, callback, and block closing braces are exempt and should
+  stay on their own line when that fits the local style. When a function,
+  lambda, callback, or block body spans multiple lines, do not put its closing
+  `}` at the end of the previous line.
+- For arrays and tuple-like lists, do not place the closing `]` at the
+  beginning of a line. Keep `]` on the same line as the final element unless
+  that would violate the line limit.
+- For function and method calls, do not place the closing `)` at the beginning
+  of a line. The only TypeScript/TSX exception is the closing parameter `)` of a
+  multi-line function declaration.
+- When writing braces on a single line in TypeScript or TSX JavaScript
+  context, put exactly one space inside the braces, as in `{ value }` or
+  `{ key: value }`.
+- Do not add inner spaces to React/JSX expression braces, as in
+  `prop={value}`, `{children}`, or `<Component>{{...props}}</Component>`.
 - Keep a tag's closing marker on the same line as the final prop when the tag
   spans multiple lines.
 - Do not put `/>` or `>` on its own line unless the existing surrounding code
@@ -247,6 +362,585 @@ const value =
 - Do not use a leading semicolon for expression statements such as
   `;([...]).forEach(...)`; rewrite the expression to avoid ASI hazards
   explicitly, for example with `void`.
+- Do not insert `void` mechanically before ordinary event-handler or callback
+  calls merely because the callee returns a `Promise`. If the surrounding code
+  already uses a plain expression statement such as
+  `onClick={() => requestActiveTab ('theme')}`, preserve that style unless a
+  local rule or type requirement truly forces `void`. Adding unnecessary
+  `void` is a medium-severity style violation.
+- When fixing formatting, never change operator binding, evaluation order,
+  tuple/comma behaviour, or any other expression structure. A formatting pass
+  that changes how `!==`, `??`, `?:`, `&&`, `||`, or `,` binds is a capital
+  offence.
+- In TypeScript and TSX, do not mechanically verticalise short call tails,
+  short object literals, or short callback bodies that already fit the local
+  line-length and delimiter rules. Expanding compact local code without a
+  readability need is a minor style violation.
+- In TypeScript and TSX, treat short object literals, short returned objects,
+  short typed object shapes, and short function-call object arguments as
+  compact associative syntax by default. If they fit locally, keep the opening
+  `{` on the same line as the first property and keep the closing `}` on the
+  same line as the final property. Do not explode them into vertical
+  Prettier-style blocks without a concrete readability or line-length reason.
+- In TypeScript and TSX, when a compact associative form is broken across two
+  lines, keep the opening `{` with the first property and the closing `}` with
+  the final property. A shape like `{\n    key: value,\n}` is wrong even when
+  line length would permit it.
+- In TypeScript and TSX, when a short call such as `apiGet<...> (...)`,
+  `apiPatch<...> (...)`, `setState (...)`, `updateClientSettings (...)`, or
+  `window.dispatchEvent (...)` already fits within the local style, do not
+  add extra vertical layers around the object argument or callback body.
+- In TypeScript and TSX, after editing a file, inspect the file tail and
+  remove meaningless blank lines before `export default` or the end of file.
+  A stray empty line before `export default` is a minor style offence.
+- Use correct British English spelling for new identifiers, filenames,
+  component names, helper names, comments, and developer-facing prose unless
+  editing an already established American-English API that must keep its
+  existing spelling for compatibility.
+- Prefer British English spellings such as `behaviour`, `colour`, `realise`,
+  `theatre`, `centre`, `favourite`, `optimise`, and `catalogue`.
+- Avoid American or Canadian spellings such as `behavior`, `color`, `realize`,
+  `theater`, `center`, `favorite`, `optimize`, and `catalog`.
+- Even when an external library or API uses the wrong spelling, prefer to
+  correct it at the local boundary and use proper British English names in this
+  codebase. For example, prefer `import { color: colour } from '@external-lib'`
+  over spreading `color` through local code.
+- Apply the same boundary correction to object destructuring, wrapper helpers,
+  adapter layers, and local variable names when doing so does not break the
+  external contract.
+- For this repository, prefer names such as `BehaviourSettingsSection.tsx`, not
+  `BehaviorSettingsSection.tsx`.
+
+### Additional style offences and penalties
+
+Use this section for recurrent failure modes that are easy to miss when
+applying the delimiter rules mechanically.
+
+#### Unnecessary `void` before ordinary callbacks
+
+Bad:
+
+```ts
+onClick={() => void requestActiveTab ('theme')}
+```
+
+Good:
+
+```ts
+onClick={() => requestActiveTab ('theme')}
+```
+
+Penalty: medium-severity offence. The code still works, but it pollutes the
+local style and usually signals that the edit was made mechanically rather than
+by reading the surrounding code.
+
+#### Formatting that changes expression structure
+
+Bad:
+
+```ts
+const hasUnsavedChanges =
+    serialiseThemeDraft (draftThemeSlots)
+    !== (serialiseThemeDraft (savedThemeSlots),
+	 draftActiveThemeMode !== savedThemeMode)
+```
+
+Good:
+
+```ts
+const hasUnsavedChanges =
+    serialiseThemeDraft (draftThemeSlots)
+    !== serialiseThemeDraft (savedThemeSlots)
+    || draftThemeMode !== savedThemeMode
+```
+
+Penalty: capital offence. Formatting must never corrupt the meaning of an
+expression.
+
+#### Mechanical vertical expansion of compact local code
+
+Bad:
+
+```ts
+const nextState = {
+    open,
+    activeTab }
+
+setDirtyStates (
+    current => ({
+	current,
+	key:  value }),
+)
+```
+
+Good:
+
+```ts
+const nextState = { open, activeTab }
+
+setDirtyStates (
+    current => ({
+	current,
+	key:  value }))
+```
+
+Penalty: minor offence when semantics stay intact. It is not necessarily
+broken, but it ignores the repository's compact associative style.
+
+#### Prettier-style exploded object literals that should stay compact
+
+Bad:
+
+```ts
+const next = {
+    enabled: keyboard?.enabled !== false,
+    bindings: normaliseKeyboardBindings (keyboard?.bindings),
+}
+```
+
+Good:
+
+```ts
+const next = {
+    enabled: keyboard?.enabled !== false,
+    bindings: normaliseKeyboardBindings (keyboard?.bindings) }
+```
+
+Also good when short enough:
+
+```ts
+const next = { enabled: keyboard?.enabled !== false,
+	       bindings: normaliseKeyboardBindings (keyboard?.bindings) }
+```
+
+Rule: for compact associative syntax, keep `{` with the first property and `}`
+with the final property unless line length truly forces a different shape.
+Do not mechanically apply the common Prettier block form.
+Penalty: medium-severity offence. The code still runs, but it violates a core
+repository formatting habit that must be preserved consistently.
+
+#### Exploded object arguments inside short calls
+
+Bad:
+
+```ts
+updateClientSettings (settings => ({
+    ...settings,
+    keyboard: next,
+}))
+```
+
+Good:
+
+```ts
+updateClientSettings (settings => ({
+    ...settings,
+    keyboard: next }))
+```
+
+Rule: a call-expression closing `)` must not drift onto its own line, and a
+short object argument should not be exploded more than necessary. Keep the
+callback's returned object compact when it fits.
+Penalty: medium-severity offence. This usually means the edit was formatted
+mechanically instead of by reading the local style.
+
+#### Stray blank line before `export default`
+
+Bad:
+
+```ts
+const Component: FC = () => {
+  return <div/>
+}
+
+
+export default Component
+```
+
+Good:
+
+```ts
+const Component: FC = () => {
+  return <div/>
+}
+
+export default Component
+```
+
+Rule: do not leave an extra empty line between the last top-level declaration
+and `export default` unless some surrounding file structure genuinely requires
+visual separation.
+Penalty: minor offence. It is small, but it is easy to avoid and should not
+recur.
+
+### Frontend delimiter decision table
+
+Use this table before accepting any edited TypeScript or TSX hunk. The table is
+more authoritative than formatter habit.
+
+#### Import and export named bindings
+
+Bad:
+
+```ts
+import {
+    Button,
+    Card,
+} from '@/components/ui'
+```
+
+Good:
+
+```ts
+import { Button,
+	 Card } from '@/components/ui'
+```
+
+Also acceptable when short:
+
+```ts
+import { Button, Card } from '@/components/ui'
+```
+
+Rule: named-binding `}` is associative-array-style syntax. It must not be alone
+at the beginning of a line. Prefer keeping `{` with the first binding and `}`
+with the final binding when this fits the line limit.
+Penalty: capital offence. This is one of the core associative-brace rules.
+
+#### Type literals
+
+Bad:
+
+```ts
+type Props = {
+    open: boolean
+    onOpenChange: (open: boolean) => void
+}
+```
+
+Good:
+
+```ts
+type Props = {
+    open: boolean
+    onOpenChange: (open: boolean) => void }
+```
+
+Rule: type-literal `}` is not a block close. It must stay on the same line as
+the final property unless that would break the hard line limit.
+Penalty: capital offence. Mistaking a type-literal `}` for a block `}` is one
+of the recurring death-class errors.
+
+#### Object literals
+
+Bad:
+
+```ts
+const value = {
+    open,
+    activeScope,
+}
+```
+
+Good:
+
+```ts
+const value = {
+    open,
+    activeScope }
+```
+
+Bad:
+
+```ts
+const value = useMemo (() => ({
+    open,
+    activeScope,
+}), [open, activeScope])
+```
+
+Good:
+
+```ts
+const value = useMemo (() => ({
+    open,
+    activeScope }), [open, activeScope])
+```
+
+Rule: object-literal `}` is associative-array-style syntax. It must not be on a
+line by itself. Keep it with the final property, and keep call `)` off the
+beginning of a line.
+Penalty: capital offence. Wrong object-literal `}` placement and wrong call
+`)` placement are both death-class violations here.
+
+#### Destructuring parameters
+
+Bad:
+
+```tsx
+const Component: FC<Props> = ({
+    open,
+    onOpenChange,
+}) => {
+  return null
+}
+```
+
+Good:
+
+```tsx
+const Component: FC<Props> = (
+    { open,
+      onOpenChange },
+) => {
+  return null
+}
+```
+
+Rule: when a React component or helper takes a destructured object parameter
+that spans multiple lines, do not use the Prettier-style `= ({ ... }) =>`
+shape. Put the function parameter list on its own lines. The destructuring `}`
+stays with the final binding. The parameter-list `)` is then allowed and
+required at the beginning of its own line.
+Penalty: capital offence. This pattern is a primary source of repeated TSX
+style regressions.
+
+#### Inline typed destructuring parameter
+
+Good:
+
+```ts
+const RouteTransitionWrapper = ({ user, setUser }: {
+    user:     User | null
+    setUser:  Dispatch<SetStateAction<User | null>> }) => {
+  return null
+}
+```
+
+Bad:
+
+```ts
+const RouteTransitionWrapper = ({ user, setUser }: {
+    user:     User | null
+    setUser:  Dispatch<SetStateAction<User | null>>
+}) => {
+  return null
+}
+```
+
+Rule: this is not a separately split parameter-list block. The line break is
+inside the inline type. Keep the type-literal `}` and parameter-list `)` on the
+same line as the final type property.
+Penalty: capital offence. Misclassifying this case means the delimiter review
+has failed at the syntax-role level.
+
+#### Multi-line normal parameter list
+
+Bad:
+
+```ts
+const updateDraft = <Key extends keyof Settings,> (
+    key: Key,
+    value: Settings[Key]) => {
+  return null
+}
+```
+
+Good:
+
+```ts
+const updateDraft = <Key extends keyof Settings,> (
+    key:    Key,
+    value:  Settings[Key],
+) => {
+  return null
+}
+```
+
+Rule: when the parameter list itself is split across multiple parameter lines,
+the closing parameter `)` goes at the beginning of its own line before `=>` or
+the return type.
+Penalty: capital offence. This is the main allowed exception for a leading `)`,
+so getting it wrong destroys the whole rule set.
+
+#### Function and callback blocks
+
+Bad:
+
+```ts
+const handleSave = () => { save ()
+}
+```
+
+Bad:
+
+```ts
+const handleSave = () => {
+  save () }
+```
+
+Good:
+
+```ts
+const handleSave = () => {
+  save ()
+}
+```
+
+Rule: block `}` closes executable code, not associative data. Multi-line
+function, lambda, callback, `if`, `for`, `switch`, and similar block braces
+belong on their own line.
+Penalty: capital offence. Confusing block `}` with associative `}` is a
+death-class delimiter error.
+
+#### Function and method calls
+
+Bad:
+
+```ts
+const value = compute (
+    first,
+    second
+)
+```
+
+Good:
+
+```ts
+const value = compute (
+    first,
+    second)
+```
+
+Rule: call-expression `)` must not be at the beginning of a line. The exception
+for leading `)` applies only to function declaration parameter lists, never to
+calls.
+Penalty: capital offence. A leading call `)` is one of the clearest death-class
+violations in this codebase.
+
+#### JSX closing markers
+
+Bad:
+
+```tsx
+<Button
+    type="button"
+    onClick={handleSave}
+>
+  保存
+</Button>
+)
+```
+
+Good:
+
+```tsx
+<Button
+    type="button"
+    onClick={handleSave}>
+  保存
+</Button>)
+```
+
+Bad:
+
+```tsx
+<Input
+    value={value}
+    onChange={handleChange}
+/>
+```
+
+Good:
+
+```tsx
+<Input
+    value={value}
+    onChange={handleChange}/>
+```
+
+Rule: keep `>` or `/>` with the final prop, and keep JSX closing parentheses in
+the local compact form such as `</div>)`.
+Penalty: medium-severity offence. It is usually not semantically broken, but it
+is a conspicuous TSX-style failure.
+
+#### Arrays and tuples
+
+Bad:
+
+```ts
+const items = [
+    first,
+    second,
+]
+```
+
+Good:
+
+```ts
+const items = [
+    first,
+    second]
+```
+
+Good when short:
+
+```ts
+const items = [first, second]
+```
+
+Rule: array and tuple `]` must not be at the beginning of a line. Keep it with
+the final element unless that would break the hard line limit.
+Penalty: capital offence. A leading `]` is forbidden by the same class of hard
+delimiter rule as leading associative `}` and leading call `)`.
+
+#### Single-line braces
+
+Good:
+
+```ts
+const next = { ...current, enabled: true }
+const tag = { id, name }
+```
+
+Bad:
+
+```tsx
+<Component prop={ value }/>
+```
+
+Good:
+
+```tsx
+<Component prop={value}/>
+```
+
+Rule: JavaScript object braces on one line get one inner space. JSX expression
+braces do not get inner spaces.
+Penalty: minor offence. This is not normally semantic breakage, but it still
+counts as a style miss.
+
+#### Final TypeScript/TSX self-review checklist
+
+Before reporting completion after a TypeScript or TSX edit, check the edited
+hunks line by line. Unless a step explicitly mentions JSX, it applies equally
+to `.ts` and `.tsx`:
+
+1. No import/export/type/object/destructuring `}` appears alone at the beginning
+   of a line.
+2. No call-expression `)` appears at the beginning of a line.
+3. Any leading `)` is definitely closing a function declaration parameter list,
+   not a call.
+4. Any parameter-list `)` at the end of a line is valid because the parameter
+   list itself was not split, only an inline type or destructuring shape was.
+5. No array or tuple `]` appears at the beginning of a line.
+6. Multi-line executable block `}` is on its own line.
+7. JSX `>` and `/>` stay with the final prop unless nearby code proves
+   otherwise.
+8. JSX closing parentheses keep the compact local style.
+9. Leading indentation is 4-space logical indentation with tabs used only as
+   leading 8-space compression.
+10. No line has trailing whitespace.
 
 Preferred:
 
@@ -282,7 +976,7 @@ function PostFormTagsArea ({ tags, setTags }: Props) {
 - Do not scan or summarize dependency/generated/runtime directories such as
   `node_modules`, `dist`, `tmp`, `log`, and `storage` unless explicitly needed.
 - Before touching wiki, tag, versioning, BAN, IP BAN, or authentication
-  behavior, inspect the related request specs and service objects.
+  behaviour, inspect the related request specs and service objects.
 - If frontend code changes, run only non-test verification commands that
   apply, such as `npm run build` and `npm run lint`. Run `npm run test:run`
   only when the user explicitly asks for tests.
@@ -299,4 +993,4 @@ A task is complete only when:
   explained,
 - unrelated files are not changed,
 - migrations and schema are consistent when schema changes are made,
-- user-facing behavior is documented when needed.
+- user-facing behaviour is documented when needed.

backend/AGENTS.md

@@ -72,17 +72,23 @@ service, representation, and spec.
 - Prefer precise, minimal changes.
 - Use single quotes unless interpolation or escaping makes double quotes better.
 - Do not put a space before Ruby method-call parentheses.
+- For `render`-family method calls, omit parentheses even when passing
+  keyword arguments.
 - Never put a line break immediately before `)` in Ruby.
 - Do not use `%w` or `%i` in new Ruby code.
 - Never write a Ruby line longer than 99 characters.
 - Aim to keep Ruby lines within 79 characters where practical.
 - For small Ruby method definitions that take keyword arguments, match the
   local no-parentheses style when nearby code uses it.
+- When an `if` condition is split across multiple lines and combines clauses
+  with `&&` or `||`, wrap the whole condition in parentheses.
 - Treat Ruby hash `{ ... }` style and Ruby block `{ ... }` style as separate
   rules.
 - Do not format Ruby hashes like Ruby blocks.
 - For Ruby hashes, keep the closing `}` on the same line as the final pair.
 - Keep the first pair on the same line as `{` by default.
+- Short Ruby hashes may stay visually compact across two lines with the first
+  pair kept on the opening line and aligned continuation pairs below it.
 - If the hash would exceed the line limit, break after `{` and indent pairs
   by 4 spaces.
 - Put one logical pair per line when the expression would otherwise become

backend/app/controllers/gekanator_posts_controller.rb

@@ -7,13 +7,24 @@ class GekanatorPostsController < ApplicationController
         .order(Arel.sql(
             'COALESCE(posts.original_created_before - INTERVAL 1 MINUTE, ' \
             'posts.original_created_from, posts.created_at) DESC, posts.id DESC'))
+        .to_a
 
-    render json: { posts: posts.map { |post| post_json(post) } }
+    active_tags_by_post_id =
+        posts.each_with_object({ }) do |post, h|
+          h[post.id] = post.tags.reject(&:deprecated?)
+        end
+
+    render json: {
+      posts: posts.map { |post|
+        post_json(post,
+                  active_tags_by_post_id:)
+      }
+    }
   end
 
   private
 
-  def post_json post
+  def post_json post, active_tags_by_post_id:
     {
       id: post.id,
       url: post.url,
@@ -22,16 +33,26 @@ class GekanatorPostsController < ApplicationController
       thumbnail_base: post.thumbnail_base,
       original_created_from: post.original_created_from,
       original_created_before: post.original_created_before,
-      post_similarity_edges: post.post_similarities.map { |similarity|
-        {
-          target_post_id: similarity.target_post_id,
-          cos: similarity.cos.to_f
-        }
-      },
-      tags: post.tags.map { |tag| tag_json(tag) }
+      post_similarity_edges: post_similarity_edges_json(
+          post,
+          active_tags_by_post_id:),
+      tags: active_tags_by_post_id.fetch(post.id, []).map { |tag| tag_json(tag) }
     }
   end
 
+  def post_similarity_edges_json post, active_tags_by_post_id:
+    post
+        .post_similarities
+        .filter_map do |similarity|
+          next unless active_tags_by_post_id.key?(similarity.target_post_id)
+
+          {
+            target_post_id: similarity.target_post_id,
+            cos: similarity.cos.to_f
+          }
+        end
+  end
+
   def tag_json tag
     {
       id: tag.id,

backend/app/controllers/gekanator_questions_controller.rb

@@ -5,9 +5,16 @@ class GekanatorQuestionsController < ApplicationController
         .accepted
         .includes(:gekanator_question_examples)
         .order(priority_weight: :desc, id: :asc)
+        .to_a
+    deprecated_tag_keys = deprecated_tag_keys_for(questions)
 
     render json: {
-      questions: questions.map { |question| question_json(question) }
+      questions: questions.filter_map { |question|
+        json = question_json(question)
+        next if hidden_question?(json[:condition], deprecated_tag_keys)
+
+        json
+      }
     }
   end
 
@@ -100,4 +107,41 @@ class GekanatorQuestionsController < ApplicationController
         .first
         &.first
   end
+
+  def deprecated_tag_keys_for questions
+    tag_keys = questions.filter_map { |question|
+      condition = condition_json(question.condition)
+      next unless condition['type'] == 'tag'
+
+      condition['key'].to_s.presence
+    }.uniq
+    return {} if tag_keys.empty?
+
+    categories = []
+    names = []
+    tag_keys.each do |key|
+      category, name = parse_tag_key(key)
+      categories << category
+      names << name
+    end
+
+    Tag
+        .joins(:tag_name)
+        .where(category: categories.uniq)
+        .where(tag_names: { name: names.uniq })
+        .where.not(deprecated_at: nil)
+        .pluck('tags.category', 'tag_names.name')
+        .each_with_object({ }) do |(category, name), h|
+          h["#{ category }:#{ name }"] = true
+        end
+  end
+
+  def hidden_question? condition, deprecated_tag_keys
+    condition[:type] == 'tag' && deprecated_tag_keys[condition[:key].to_s]
+  end
+
+  def parse_tag_key key
+    parts = key.to_s.split(':')
+    [parts.first.to_s, parts.drop(1).join(':')]
+  end
 end

backend/app/controllers/material_sync_suppressions_controller.rb

@@ -0,0 +1,49 @@
+class MaterialSyncSuppressionsController < ApplicationController
+  def index
+    return head :unauthorized unless current_user
+    return head :forbidden unless current_user.gte_member?
+
+    suppressions =
+        MaterialSyncSuppression
+        .includes(:created_by_user)
+        .order(created_at: :desc, id: :desc)
+
+    render json: { suppressions: suppressions.map { |s| repr(s) } }
+  end
+
+  def create
+    return head :unauthorized unless current_user
+    return head :forbidden unless current_user.gte_member?
+
+    suppression =
+        MaterialSyncSuppressionRegistrar.create!(suppression_params,
+                                                 created_by_user: current_user)
+
+    render json: repr(suppression), status: :created
+  rescue ActiveRecord::RecordInvalid => e
+    render_validation_error e.record
+  end
+
+  private
+
+  def suppression_params
+    params.permit(:source_kind,
+                  :source_uri,
+                  :drive_path,
+                  :drive_file_id,
+                  :reason)
+  end
+
+  def repr suppression
+    { id: suppression.id,
+      source_kind: suppression.source_kind,
+      source_uri: suppression.source_uri,
+      drive_path: suppression.drive_path,
+      drive_file_id: suppression.drive_file_id,
+      normalized_source_key: suppression.normalized_source_key,
+      reason: suppression.reason,
+      created_by_user: suppression.created_by_user&.as_json(UserRepr::BASE),
+      created_at: suppression.created_at,
+      updated_at: suppression.updated_at }
+  end
+end

backend/app/controllers/material_versions_controller.rb

@@ -0,0 +1,54 @@
+class MaterialVersionsController < ApplicationController
+  def index
+    page = (params[:page].presence || 1).to_i
+    limit = (params[:limit].presence || 20).to_i
+
+    page = 1 if page < 1
+    limit = 1 if limit < 1
+
+    offset = (page - 1) * limit
+
+    q = MaterialVersion.includes(:created_by_user)
+    q = q.where(material_id: params[:material_id]) if params[:material_id].present?
+    q = q.where(tag_name: params[:tag].to_s.strip) if params[:tag].present?
+    q = q.where(event_type: params[:event_type]) if params[:event_type].present?
+
+    count = q.except(:order, :limit, :offset).count
+    versions =
+        q
+        .order(Arel.sql('material_versions.created_at DESC, material_versions.id DESC'))
+        .limit(limit)
+        .offset(offset)
+
+    render json: { versions: serialise_versions(versions), count: }
+  end
+
+  private
+
+  def serialise_versions rows
+    rows.map do |row|
+      { id: row.id,
+        material_id: row.material_id,
+        version_no: row.version_no,
+        event_type: row.event_type,
+        tag_id: row.tag_id,
+        tag_name: row.tag_name,
+        tag_category: row.tag_category,
+        url: row.url,
+        source_kind: row.source_kind,
+        source_uri: row.source_uri,
+        source_path: row.source_path,
+        source_file_id: row.source_file_id,
+        normalized_source_key: row.normalized_source_key,
+        file_blob_id: row.file_blob_id,
+        file_filename: row.file_filename,
+        file_content_type: row.file_content_type,
+        file_byte_size: row.file_byte_size,
+        file_sha256: row.file_sha256,
+        export_paths_json: row.export_paths_hash,
+        discarded_at: row.discarded_at,
+        created_by_user: row.created_by_user&.as_json(UserRepr::BASE),
+        created_at: row.created_at }
+    end
+  end
+end

backend/app/controllers/materials_controller.rb

@@ -1,4 +1,11 @@
+require 'set'
+
+
 class MaterialsController < ApplicationController
+  rescue_from MaterialZipExporter::EmptyExportError, with: :render_zip_empty
+  rescue_from MaterialZipExporter::DuplicatePathError, with: :render_zip_duplicate_path
+  rescue_from MaterialZipExporter::MissingFileError, with: :render_zip_missing_file
+
   def index
     page = (params[:page].presence || 1).to_i
     limit = (params[:limit].presence || 20).to_i
@@ -8,54 +15,98 @@ class MaterialsController < ApplicationController
 
     offset = (page - 1) * limit
 
-    tag_id = params[:tag_id].presence
-    parent_id = params[:parent_id].presence
+    filters = material_index_filters
+    tag_graph = material_index_tag_graph(filters)
+    q = Material.includes(:material_export_items,
+                          thumbnail_attachment: :blob,
+                          file_attachment: :blob,
+                          tag: :tag_name)
+    q = q.where(tag_id: nil) if filters[:tag_state] == 'untagged'
+    q = q.where.not(tag_id: nil) if filters[:tag_state] == 'tagged'
+    q = apply_material_tag_filter(q, filters, tag_graph)
+    q = q.where('materials.created_at >= ?', filters[:created_from]) if filters[:created_from]
+    q = q.where('materials.created_at <= ?', filters[:created_to]) if filters[:created_to]
+    q = q.where('materials.updated_at >= ?', filters[:updated_from]) if filters[:updated_from]
+    q = q.where('materials.updated_at <= ?', filters[:updated_to]) if filters[:updated_to]
 
-    q = Material.includes(:tag, :created_by_user).with_attached_file
-    q = q.where(tag_id:) if tag_id
-    q = q.where(parent_id:) if parent_id
+    q = material_index_join_tag_name(q) if material_index_needs_tag_name?(filters)
+    q = material_index_join_file_blob(q) if material_index_needs_file_blob?(filters)
+    q = apply_material_query(q, filters[:q]) if filters[:q].present?
+    q = apply_material_media_kind(q, filters[:media_kind])
 
-    count = q.count
-    materials = q.order(created_at: :desc, id: :desc).limit(limit).offset(offset)
+    count = q.distinct.count(:id)
+    materials =
+        q
+        .order(Arel.sql(material_index_order_sql(filters)))
+        .limit(limit)
+        .offset(offset)
+        .to_a
 
-    render json: { materials: MaterialRepr.many(materials, host: request.base_url), count: count }
+    response = { materials: MaterialRepr.list_many(materials, host: request.base_url),
+                 count: }
+    if filters[:tag_id]
+      response[:tag_scope] = material_index_tag_scope(filters, tag_graph)
+    end
+    if filters[:group_by] == 'parent_tag'
+      response[:groups] = material_index_groups(materials, tag_graph)
+    end
+
+    render json: response
   end
 
   def show
     material =
         Material
-        .includes(:tag)
+        .includes(:tag, :material_export_items)
+        .with_attached_thumbnail
         .with_attached_file
         .find_by(id: params[:id])
     return head :not_found unless material
 
-    wiki_page_body = material.tag.tag_name.wiki_page&.current_revision&.body
+    wiki_page_body = material.tag&.tag_name&.wiki_page&.current_revision&.body
 
     render json: MaterialRepr.base(material, host: request.base_url).merge(wiki_page_body:)
   end
 
   def create
     return head :unauthorized unless current_user
+    return head :forbidden unless current_user.gte_member?
 
     tag_name_raw = params[:tag].to_s.strip
     file = params[:file]
+    file_sha256 = MaterialFileSha256.from_upload(file)
     url = params[:url].to_s.strip.presence
     return render_unprocessable_entity('タグは必須です．', field: :tag) if tag_name_raw.blank?
     if file.blank? && url.blank?
       return render_validation_error fields: { file: ['ファイルまたは URL は必須です．'],
                                                url: ['ファイルまたは URL は必須です．'] }
     end
+    block = MaterialImportBlockMatcher.match_for_sha256(file_sha256)
+    return render_material_import_block(block) if block
 
-    tag_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
-    tag = tag_name.tag
-    tag = Tag.create!(tag_name:, category: :material) unless tag
+    uploaded_blob = build_uploaded_material_blob!(file, file_sha256)
+    material = nil
 
-    material = Material.new(tag:, url:,
-                            created_by_user: current_user,
-                            updated_by_user: current_user)
-    material.file.attach(file)
+    begin
+      Material.transaction do
+        tag = resolve_material_tag!(tag_name_raw)
+        material = Material.new(tag:, url:,
+                                created_by_user: current_user,
+                                updated_by_user: current_user)
+        material.file.attach(uploaded_blob) if uploaded_blob
+        material.save!
+        TagVersioning.record_tag_snapshot!(tag, created_by_user: current_user)
+        upsert_export_paths!(material)
+        MaterialVersionRecorder.record!(material:, event_type: :create,
+                                        created_by_user: current_user)
+      end
+    rescue StandardError
+      uploaded_blob&.purge_later
+      raise
+    end
 
-    if material.save
+    if material
+      log_thumbnail_generation(material, MaterialThumbnailGenerator.generate!(material))
       render json: MaterialRepr.base(material, host: request.base_url), status: :created
     else
       render_validation_error material
@@ -71,29 +122,42 @@ class MaterialsController < ApplicationController
 
     tag_name_raw = params[:tag].to_s.strip
     file = params[:file]
-    url = params[:url].to_s.strip.presence
+    file_sha256 = MaterialFileSha256.from_upload(file)
+    url = params.key?(:url) ? params[:url].to_s.strip.presence : material.url
     return render_unprocessable_entity('タグは必須です．', field: :tag) if tag_name_raw.blank?
-    if file.blank? && url.blank?
+    if file.blank? && url.blank? && !material.file.attached?
       return render_validation_error fields: { file: ['ファイルまたは URL は必須です．'],
                                                url: ['ファイルまたは URL は必須です．'] }
     end
+    block = MaterialImportBlockMatcher.match_for_sha256(file_sha256)
+    return render_material_import_block(block) if block
 
-    tag_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
-    tag = tag_name.tag
-    tag = Tag.create!(tag_name:, category: :material) unless tag
+    uploaded_blob = build_uploaded_material_blob!(file, file_sha256)
 
-    material.update!(tag:, url:, updated_by_user: current_user)
-    if file
-      material.file.attach(file)
-    else
-      material.file.purge
+    begin
+      Material.transaction do
+        MaterialVersionRecorder.ensure_snapshot!(material, created_by_user: current_user)
+        tag = resolve_material_tag!(tag_name_raw)
+        material.assign_attributes(tag:, url:, updated_by_user: current_user)
+        if uploaded_blob
+          material.file.attach(uploaded_blob)
+        elsif params.key?(:url) && url.present? && file.blank?
+          material.file.detach
+        end
+        material.save!
+        TagVersioning.record_tag_snapshot!(tag, created_by_user: current_user)
+        upsert_export_paths!(material)
+        MaterialVersionRecorder.record!(material:, event_type: :update,
+                                        created_by_user: current_user)
+      end
+    rescue StandardError
+      uploaded_blob&.purge_later
+      raise
     end
 
-    if material.save
-      render json: MaterialRepr.base(material, host: request.base_url)
-    else
-      render_validation_error material
-    end
+    log_thumbnail_generation(material, MaterialThumbnailGenerator.generate!(material))
+
+    render json: MaterialRepr.base(material, host: request.base_url)
   end
 
   def destroy
@@ -103,7 +167,381 @@ class MaterialsController < ApplicationController
     material = Material.find_by(id: params[:id])
     return head :not_found unless material
 
-    material.discard
+    Material.transaction do
+      MaterialVersionRecorder.ensure_snapshot!(material, created_by_user: current_user)
+      material.discard!
+      MaterialVersionRecorder.record!(material:, event_type: :discard,
+                                      created_by_user: current_user)
+    end
     head :no_content
   end
+
+  def download
+    zip = MaterialZipExporter.new(profile: params[:profile],
+                                  tag_id: params[:tag_id]).export
+    profile = params[:profile].presence || 'legacy_drive'
+    send_data zip,
+              type: 'application/zip',
+              disposition: 'attachment',
+              filename: "btrc-materials-#{ profile }.zip"
+  end
+
+  private
+
+  def material_index_filters
+    tag_state = params[:tag_state].to_s.presence
+    tag_state = 'untagged' if bool?(:unclassified)
+    tag_state = 'all' unless ['all', 'tagged', 'untagged'].include?(tag_state)
+
+    media_kind = params[:media_kind].to_s.presence
+    unless ['all', 'image', 'video', 'audio', 'file_other', 'url_only'].include?(media_kind)
+      media_kind = 'all'
+    end
+
+    sort = params[:sort].to_s.presence
+    unless ['created_at', 'updated_at', 'tag_name', 'media_kind', 'file_byte_size',
+            'version_no', 'id'].include?(sort)
+      sort = 'created_at'
+    end
+
+    direction = params[:direction].to_s.downcase
+    direction = 'desc' unless ['asc', 'desc'].include?(direction)
+
+    group_by = params[:group_by].to_s.presence
+    group_by = 'none' unless ['none', 'parent_tag'].include?(group_by)
+
+    tag_id = params[:tag_id].to_i
+    tag_id = nil if tag_id <= 0
+
+    { q: params[:q].to_s.strip.presence,
+      tag_state:,
+      media_kind:,
+      tag_id:,
+      include_descendants: bool?(:include_descendants),
+      group_by:,
+      created_from: parse_time_param(:created_from),
+      created_to: parse_time_param(:created_to),
+      updated_from: parse_time_param(:updated_from),
+      updated_to: parse_time_param(:updated_to),
+      sort:,
+      direction: }
+  end
+
+  def parse_time_param name
+    value = params[name].to_s.strip
+    return nil if value.blank?
+
+    Time.zone.parse(value)
+  rescue ArgumentError
+    nil
+  end
+
+  def resolve_material_tag! tag_name_raw
+    tag_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
+    tag = tag_name.tag
+    tag || Tag.create!(tag_name:, category: :material)
+  end
+
+  def material_index_needs_tag_name? filters
+    filters[:q].present? || filters[:sort] == 'tag_name'
+  end
+
+  def material_index_needs_file_blob? filters
+    filters[:q].present? ||
+        filters[:media_kind] != 'all' ||
+        ['media_kind', 'file_byte_size'].include?(filters[:sort])
+  end
+
+  def material_index_join_tag_name q
+    q.left_joins(tag: :tag_name)
+  end
+
+  def material_index_join_file_blob q
+    q.joins(<<~SQL.squish)
+      LEFT JOIN active_storage_attachments material_file_attachments
+        ON material_file_attachments.record_type = 'Material'
+       AND material_file_attachments.record_id = materials.id
+       AND material_file_attachments.name = 'file'
+      LEFT JOIN active_storage_blobs material_file_blobs
+        ON material_file_blobs.id = material_file_attachments.blob_id
+    SQL
+  end
+
+  def apply_material_query q, term
+    like = "%#{ ActiveRecord::Base.sanitize_sql_like(term) }%"
+    q.where('tag_names.name LIKE :q OR materials.url LIKE :q OR ' \
+            'material_file_blobs.filename LIKE :q',
+            q: like)
+  end
+
+  def apply_material_media_kind q, media_kind
+    case media_kind
+    when 'image'
+      q.where('material_file_blobs.content_type LIKE ?', 'image/%')
+    when 'video'
+      q.where('material_file_blobs.content_type LIKE ?', 'video/%')
+    when 'audio'
+      q.where('material_file_blobs.content_type LIKE ?', 'audio/%')
+    when 'file_other'
+      q.where('material_file_attachments.id IS NOT NULL')
+       .where.not('material_file_blobs.content_type LIKE ?', 'image/%')
+       .where.not('material_file_blobs.content_type LIKE ?', 'video/%')
+       .where.not('material_file_blobs.content_type LIKE ?', 'audio/%')
+    when 'url_only'
+      q.where('material_file_attachments.id IS NULL').where.not(url: [nil, ''])
+    else
+      q
+    end
+  end
+
+  def apply_material_tag_filter q, filters, tag_graph
+    return q unless filters[:tag_id]
+
+    tag_ids =
+        if tag_graph
+          tag_graph[:scope_tag_ids]
+        else
+          [filters[:tag_id]]
+        end
+
+    q.where(tag_id: tag_ids)
+  end
+
+  def material_index_tag_graph filters
+    return nil unless filters[:tag_id]
+
+    children_by_parent_id = Hash.new { |h, k| h[k] = [] }
+    TagImplication.pluck(:parent_tag_id, :tag_id).each do |parent_id, child_id|
+      children_by_parent_id[parent_id] << child_id
+    end
+
+    scope_tag_ids =
+        if filters[:include_descendants]
+          collect_material_descendant_ids(filters[:tag_id], children_by_parent_id)
+        else
+          Set.new([filters[:tag_id]])
+        end
+    tags_by_id =
+        Tag
+        .joins(:tag_name)
+        .where(id: scope_tag_ids)
+        .pluck('tags.id', 'tag_names.name', 'tags.category', 'tags.deprecated_at')
+        .each_with_object({ }) do |(id, name, category, deprecated_at), hash|
+          hash[id] = { id:, name:, category:, deprecated: deprecated_at.present? }
+        end
+
+    selected_tag = tags_by_id[filters[:tag_id]]
+    return nil unless selected_tag
+
+    group_tag_id_by_tag_id = { }
+    children_by_parent_id[filters[:tag_id]].each do |child_tag_id|
+      assign_material_group_branch(child_tag_id,
+                                   children_by_parent_id:,
+                                   tags_by_id:,
+                                   group_tag_id_by_tag_id:,
+                                   current_group_tag_id: nil,
+                                   seen: Set.new([filters[:tag_id]]))
+    end
+
+    { selected_tag_id: filters[:tag_id],
+      selected_tag:,
+      scope_tag_ids: scope_tag_ids.to_a,
+      tags_by_id:,
+      group_tag_id_by_tag_id: }
+  end
+
+  def collect_material_descendant_ids selected_tag_id, children_by_parent_id
+    ids = Set.new([selected_tag_id])
+    stack = [selected_tag_id]
+
+    until stack.empty?
+      tag_id = stack.pop
+      children_by_parent_id[tag_id].each do |child_tag_id|
+        next if ids.include?(child_tag_id)
+
+        ids << child_tag_id
+        stack << child_tag_id
+      end
+    end
+
+    ids
+  end
+
+  def assign_material_group_branch tag_id, children_by_parent_id:, tags_by_id:,
+                                   group_tag_id_by_tag_id:, current_group_tag_id:, seen:
+    return if seen.include?(tag_id)
+
+    tag = tags_by_id[tag_id]
+    return unless tag
+
+    seen = seen.dup << tag_id
+    next_group_tag_id = current_group_tag_id
+    next_group_tag_id = tag_id if next_group_tag_id.nil? && !tag[:deprecated]
+    group_tag_id_by_tag_id[tag_id] = next_group_tag_id if next_group_tag_id
+
+    children_by_parent_id[tag_id].each do |child_tag_id|
+      assign_material_group_branch(child_tag_id,
+                                   children_by_parent_id:,
+                                   tags_by_id:,
+                                   group_tag_id_by_tag_id:,
+                                   current_group_tag_id: next_group_tag_id,
+                                   seen:)
+    end
+  end
+
+  def material_index_groups materials, tag_graph
+    return [] unless tag_graph
+
+    groups_by_key = { }
+
+    materials.each do |material|
+      next unless material.tag_id
+
+      group_tag_id =
+          if material.tag_id == tag_graph[:selected_tag_id]
+            tag_graph[:selected_tag_id]
+          else
+            tag_graph[:group_tag_id_by_tag_id][material.tag_id] || tag_graph[:selected_tag_id]
+          end
+
+      group_tag = tag_graph[:tags_by_id][group_tag_id]
+      next unless group_tag
+
+      key = "tag:#{ group_tag_id }"
+      group =
+          groups_by_key[key] ||= { key:,
+                                   tag: group_tag_repr(group_tag),
+                                   material_ids: [],
+                                   count: 0 }
+      group[:material_ids] << material.id
+      group[:count] += 1
+    end
+
+    groups_by_key.values.sort_by { |group| group[:tag][:name] }
+  end
+
+  def material_index_tag_scope filters, tag_graph
+    return nil unless tag_graph
+
+    {
+      tag: group_tag_repr(tag_graph[:selected_tag]),
+      include_descendants: filters[:include_descendants]
+    }
+  end
+
+  def group_tag_repr group_tag
+    { id: group_tag[:id],
+      name: group_tag[:name],
+      category: group_tag[:category] }
+  end
+
+  def material_index_order_sql filters
+    direction = filters[:direction] == 'asc' ? 'ASC' : 'DESC'
+    sort_sql =
+        case filters[:sort]
+        when 'tag_name'
+          'tag_names.name'
+        when 'media_kind'
+          material_media_kind_sql
+        when 'file_byte_size'
+          'material_file_blobs.byte_size'
+        when 'updated_at'
+          'materials.updated_at'
+        when 'version_no'
+          'materials.version_no'
+        when 'id'
+          'materials.id'
+        else
+          'materials.created_at'
+        end
+
+    "#{ sort_sql } #{ direction }, materials.id #{ direction }"
+  end
+
+  def material_media_kind_sql
+    "CASE " \
+      "WHEN material_file_attachments.id IS NULL AND materials.url IS NOT NULL THEN 5 " \
+      "WHEN material_file_blobs.content_type LIKE 'image/%' THEN 1 " \
+      "WHEN material_file_blobs.content_type LIKE 'video/%' THEN 2 " \
+      "WHEN material_file_blobs.content_type LIKE 'audio/%' THEN 3 " \
+      "WHEN material_file_attachments.id IS NOT NULL THEN 4 " \
+      "ELSE 6 END"
+  end
+
+  def upsert_export_paths! material
+    raw = params[:export_paths]
+    return if raw.blank?
+
+    export_paths = raw.respond_to?(:to_unsafe_h) ? raw.to_unsafe_h : raw.to_h
+    export_paths.each do |profile, export_path|
+      profile = profile.to_s
+      export_path = export_path.to_s.strip
+      item = material.material_export_items.find_or_initialize_by(profile:)
+
+      if export_path.blank?
+        item.destroy! if item.persisted?
+        next
+      end
+
+      item.export_path = export_path
+      item.enabled = true
+      item.created_by_user ||= current_user
+      item.save!
+    end
+  end
+
+  def render_zip_empty
+    render_unprocessable_entity('ZIP export 対象の素材がありません．')
+  end
+
+  def render_zip_duplicate_path error
+    render_unprocessable_entity("ZIP export path が重複してゐます: #{ error.message }")
+  end
+
+  def render_zip_missing_file error
+    missing_files = error.missing_files.map do |missing_file|
+      { material_id: missing_file.material_id,
+        export_path: missing_file.export_path,
+        blob_id: missing_file.blob_id,
+        filename: missing_file.filename }
+    end
+
+    render json: { type: 'validation_error',
+                   message: 'ZIP export に必要な素材ファイルが欠損しています．',
+                   errors: { },
+                   base_errors: ['ZIP export に必要な素材ファイルが欠損しています．'],
+                   missing_files: },
+           status: :unprocessable_entity
+  end
+
+  def build_uploaded_material_blob! file, file_sha256
+    return nil unless file
+
+    file.tempfile.rewind
+
+    blob = ActiveStorage::Blob.create_and_upload!(
+        io: file.tempfile,
+        filename: file.original_filename,
+        content_type: file.content_type,
+    )
+
+    MaterialFileSha256.assign_metadata_sha256!(blob, file_sha256)
+
+    blob
+  ensure
+    file.tempfile.rewind if file&.tempfile
+  end
+
+  def render_material_import_block block
+    render_validation_error fields: { file: ["抑止された素材です: #{ block.reason }"] }
+  end
+
+  def log_thumbnail_generation material, result
+    material.reload
+    Rails.logger.info(
+        "Material thumbnail generation: material_id=#{ material.id } " \
+        "result=#{ result } " \
+        "thumbnail_attached=#{ material.thumbnail.attached? } " \
+        "content_type=#{ material.content_type }")
+  end
 end

backend/app/controllers/post_versions_controller.rb

@@ -25,6 +25,7 @@ class PostVersionsController < ApplicationController
         SQL
         .select('post_versions.*', 'prev.title AS prev_title', 'prev.url AS prev_url',
                 'prev.thumbnail_base AS prev_thumbnail_base', 'prev.tags AS prev_tags',
+                'prev.video_ms AS prev_video_ms',
                 'prev.original_created_from AS prev_original_created_from',
                 'prev.original_created_before AS prev_original_created_before')
     q = q.where('post_versions.post_id = ?', post_id) if post_id
@@ -74,6 +75,10 @@ class PostVersionsController < ApplicationController
           current: row.thumbnail_base,
           prev: row.attributes['prev_thumbnail_base']
         },
+        video_ms: {
+          current: row.video_ms,
+          prev: row.attributes['prev_video_ms']
+        },
         tags: build_version_tags(cur_tags, prev_tags),
         original_created_from: {
           current: row.original_created_from&.iso8601,

backend/app/controllers/posts_controller.rb

@@ -1,6 +1,10 @@
 class PostsController < ApplicationController
   Event = Struct.new(:post, :tag, :user, :change_type, :timestamp, keyword_init: true)
 
+  class VideoMsParseError < ArgumentError
+    ;
+  end
+
   def index
     url = params[:url].presence
     title = params[:title].presence
@@ -45,7 +49,9 @@ class PostsController < ApplicationController
         .joins("LEFT JOIN (#{ pt_max_sql }) pt_max ON pt_max.post_id = posts.id")
         .reselect('posts.*', Arel.sql("#{ updated_at_all_sql } AS updated_at_all"))
         .preload(:uploaded_user, :parents, :children,
-                 tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
+                 active_post_tags: [:sections,
+                                    { tag: [:deerjikists, :materials,
+                                            { tag_name: :wiki_page }] }])
         .with_attached_thumbnail
 
     q = q.where('posts.url LIKE ?', "%#{ url }%") if url
@@ -97,7 +103,9 @@ class PostsController < ApplicationController
 
   def random
     post = filtered_posts.preload(:uploaded_user, :parents, :children,
-                                  tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
+                                  active_post_tags: [:sections,
+                                                     { tag: [:deerjikists, :materials,
+                                                             { tag_name: :wiki_page }] }])
                          .with_attached_thumbnail
                          .order('RAND()')
                          .first
@@ -110,7 +118,9 @@ class PostsController < ApplicationController
     post =
         Post
         .includes(:uploaded_user, :parents, :children,
-                  tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
+                  active_post_tags: [:sections,
+                                     { tag: [:deerjikists, :materials,
+                                             { tag_name: :wiki_page }] }])
         .with_attached_thumbnail
         .find_by(id: params[:id])
     return head :not_found unless post
@@ -125,7 +135,7 @@ class PostsController < ApplicationController
                                  child_posts:,
                                  sibling_posts:,
                                  related:)
-                         .merge(tags: build_tag_tree_for(post.tags))
+                         .merge(tags: build_tag_tree_for(post))
   end
 
   def create
@@ -140,24 +150,27 @@ class PostsController < ApplicationController
     original_created_from = params[:original_created_from]
     original_created_before = params[:original_created_before]
     parent_post_ids = parse_parent_post_ids
+    resized_thumbnail = thumbnail.present? ? Post.resized_thumbnail_attachment(thumbnail) : nil
 
     post = Post.new(title:, url:, thumbnail_base: nil, uploaded_user: current_user,
                     original_created_from:, original_created_before:)
-    post.thumbnail.attach(thumbnail) if thumbnail.present?
+    post.thumbnail.attach(resized_thumbnail) if resized_thumbnail
 
     ApplicationRecord.transaction do
       post.save!
 
-      tags = Tag.normalise_tags!(tag_names)
+      Tag.normalise_tags!(tag_names, deny_deprecated: true, with_sections: true) =>
+          { tags:, sections: }
       TagVersioning.record_tag_snapshots!(tags, created_by_user: current_user)
 
-      tags = Tag.expand_parent_tags(tags)
-      sync_post_tags!(post, tags)
+      tags = Tag.expand_parent_tags(tags).reject(&:deprecated?)
+      post.video_ms = normalise_video_ms(tags)
+      validate_video_sections!(post.video_ms, sections)
+      post.save!
+      sync_post_tags!(post, tags, sections)
 
       sync_parent_posts!(post, parent_post_ids)
 
-      post.resized_thumbnail!
-
       PostVersionRecorder.record!(post:, event_type: :create, created_by_user: current_user)
     end
 
@@ -165,6 +178,14 @@ class PostsController < ApplicationController
     render json: PostRepr.base(post), status: :created
   rescue Tag::NicoTagNormalisationError
     render_validation_error fields: { tags: 'ニコニコ・タグは直接指定できません．' }
+  rescue Tag::DeprecatedTagNormalisationError
+    render_unprocessable_entity '廃止済みタグは付与できません．', field: :tags
+  rescue Tag::SectionLiteralParseError
+    render_validation_error fields: { tags: ['タグ区間の記法が不正です．'] }
+  rescue VideoMsParseError
+    render_validation_error fields: { video_ms: ['動画時間の記法が不正です．'] }
+  rescue MiniMagick::Error
+    render_validation_error fields: { thumbnail: ['サムネイル画像の変換に失敗しました．'] }
   rescue ArgumentError => e
     render_validation_error fields: { parent_post_ids: [e.message] }
   rescue ActiveRecord::RecordInvalid => e
@@ -221,6 +242,8 @@ class PostsController < ApplicationController
                                                  original_created_from:,
                                                  original_created_before:,
                                                  tag_names:,
+                                                 video_ms_param: params[:video_ms],
+                                                 duration_param: params[:duration],
                                                  parent_post_ids:)
 
       snapshot_to_apply =
@@ -251,10 +274,16 @@ class PostsController < ApplicationController
 
     post.reload
     json = PostRepr.base(post, current_user)
-    json['tags'] = build_tag_tree_for(post.tags)
+    json['tags'] = build_tag_tree_for(post)
     render json:, status: :ok
   rescue Tag::NicoTagNormalisationError
     render_validation_error fields: { tags: ['ニコニコ・タグは直接指定できません．'] }
+  rescue Tag::DeprecatedTagNormalisationError
+    render_unprocessable_entity '廃止済みタグは付与できません．', field: :tags
+  rescue Tag::SectionLiteralParseError
+    render_validation_error fields: { tags: ['タグ区間の記法が不正です．'] }
+  rescue VideoMsParseError
+    render_validation_error fields: { video_ms: ['動画時間の記法が不正です．'] }
   rescue ArgumentError => e
     render_validation_error fields: { parent_post_ids: [e.message] }
   rescue ActiveRecord::RecordInvalid => e
@@ -353,7 +382,7 @@ class PostsController < ApplicationController
   def tagged_post_ids_for(name) =
       Post.joins(tags: :tag_name).where(tag_names: { name: }).select(:id)
 
-  def sync_post_tags! post, desired_tags
+  def sync_post_tags! post, desired_tags, sections
     desired_tags.each do |t|
       t.save! if t.new_record?
     end
@@ -372,13 +401,21 @@ class PostsController < ApplicationController
       end
     end
 
+    PostTagSection.where(post_id: post.id).destroy_all
+    sections.each do |tag_id, ranges|
+      ranges.each do |begin_ms, end_ms|
+        PostTagSection.create!(post_id: post.id, tag_id:, begin_ms:, end_ms:)
+      end
+    end
+
     PostTag.where(post_id: post.id, tag_id: to_remove.to_a).kept.find_each do |pt|
       pt.discard_by!(current_user)
     end
   end
 
-  def build_tag_tree_for tags
-    tags = tags.to_a
+  def build_tag_tree_for post
+    post_tags = post.active_post_tags.reject { |post_tag| post_tag.tag.deprecated? }
+    tags = post_tags.map(&:tag)
     tag_ids = tags.map(&:id)
 
     implications = TagImplication.where(parent_tag_id: tag_ids, tag_id: tag_ids)
@@ -393,6 +430,9 @@ class PostsController < ApplicationController
     root_ids = tag_ids - child_ids
 
     tags_by_id = tags.index_by(&:id)
+    sections_by_tag_id = post_tags.to_h { |post_tag|
+      [post_tag.tag_id, post_tag.sections.as_json(only: [:begin_ms, :end_ms])]
+    }
 
     memo = { }
 
@@ -400,8 +440,10 @@ class PostsController < ApplicationController
       tag = tags_by_id[tag_id]
       return nil unless tag
 
+      sections = sections_by_tag_id.fetch(tag_id, [])
+
       if path.include?(tag_id)
-        return TagRepr.inline(tag).merge(children: [])
+        return TagRepr.inline(tag).merge(children: [], sections:)
       end
 
       if memo.key?(tag_id)
@@ -413,7 +455,7 @@ class PostsController < ApplicationController
 
       children = child_ids.filter_map { |cid| build_node.(cid, new_path) }
 
-      memo[tag_id] = TagRepr.inline(tag).merge(children:)
+      memo[tag_id] = TagRepr.inline(tag).merge(children:, sections:)
     end
 
     root_ids.filter_map { |id| build_node.call(id, []) }
@@ -482,6 +524,7 @@ class PostsController < ApplicationController
 
   def post_snapshot_from_version version
     { title: version.title,
+      video_ms: version.respond_to?(:video_ms) ? version.video_ms : nil,
       original_created_from: snapshot_time(version.original_created_from),
       original_created_before: snapshot_time(version.original_created_before),
       tag_names: editable_tag_names_from_version(version),
@@ -494,6 +537,7 @@ class PostsController < ApplicationController
 
   def post_snapshot_from_record post
     { title: post.title,
+      video_ms: post.video_ms,
       original_created_from: snapshot_time(post.original_created_from),
       original_created_before: snapshot_time(post.original_created_before),
       tag_names: editable_tag_names_from_post(post),
@@ -501,15 +545,41 @@ class PostsController < ApplicationController
   end
 
   def editable_tag_names_from_post post
-    post.tags.not_nico.joins(:tag_name).order('tag_names.name').pluck('tag_names.name')
+    post
+        .post_tags
+        .kept
+        .joins(tag: :tag_name)
+        .merge(Tag.not_nico)
+        .merge(Tag.where(deprecated_at: nil))
+        .includes(:sections, tag: :tag_name)
+        .order('tag_names.name')
+        .map do |post_tag|
+      name = post_tag.tag.tag_name.name
+      sections = post_tag.sections.sort_by(&:begin_ms)
+
+      next name if sections.empty?
+
+      "#{ name }#{ sections.map { Post.section_literal(_1) }.join }"
+    end
   end
 
   def post_incoming_snapshot title:, original_created_from:, original_created_before:,
-                             tag_names:, parent_post_ids:
+                             tag_names:, video_ms_param:, duration_param:, parent_post_ids:
+    Tag.normalise_tags!(tag_names, with_tagme: false, deny_deprecated: true,
+                                        with_sections: true) =>
+        { tags:, sections: }
+
+    tags = Tag.expand_parent_tags(tags).reject(&:deprecated?)
+    video_ms = normalise_video_ms(tags, video_ms_param:, duration_param:)
+    validate_video_sections!(video_ms, sections)
+
     { title:,
+      video_ms:,
       original_created_from: snapshot_time(original_created_from),
       original_created_before: snapshot_time(original_created_before),
-      tag_names: incoming_tag_names_for_snapshot(tag_names),
+      tag_names: tags.uniq(&:id).map { |tag|
+        "#{ tag.name }#{ sections[tag.id].to_a.map { section_literal(_1) }.join }"
+      }.sort,
       parent_post_ids: parent_post_ids.sort }
   end
 
@@ -532,10 +602,8 @@ class PostsController < ApplicationController
     value.to_s
   end
 
-  def incoming_tag_names_for_snapshot raw_tag_names
-    tags = Tag.normalise_tags!(raw_tag_names, with_tagme: false)
-
-    Tag.expand_parent_tags(tags).map(&:name).uniq.sort
+  def section_literal section
+    "[#{ Post.ms_to_time(section[0]) }-#{ section[1] ? Post.ms_to_time(section[1]) : '' }]"
   end
 
   def post_conflict_json post:, base_version_no:, base_snapshot:,
@@ -556,6 +624,8 @@ class PostsController < ApplicationController
   def post_snapshot_changes base_snapshot, current_snapshot, incoming_snapshot
     [scalar_snapshot_change(:title, 'タイトル',
                             base_snapshot, current_snapshot, incoming_snapshot),
+     scalar_snapshot_change(:video_ms, '動画時間',
+                            base_snapshot, current_snapshot, incoming_snapshot),
      scalar_snapshot_change(:original_created_from, 'オリジナルの作成日時（以降）',
                             base_snapshot, current_snapshot, incoming_snapshot),
      scalar_snapshot_change(:original_created_before, 'オリジナルの作成日時（より前）',
@@ -619,25 +689,32 @@ class PostsController < ApplicationController
     PostVersionRecorder.ensure_snapshot!(post, created_by_user: current_user)
 
     post.update!(title: snapshot[:title],
+                 video_ms: snapshot[:video_ms],
                  original_created_from: snapshot[:original_created_from],
                  original_created_before: snapshot[:original_created_before])
 
-    editable_tags = Tag.normalise_tags!(snapshot[:tag_names], with_tagme: false)
+    Tag.normalise_tags!(snapshot[:tag_names], with_tagme: false,
+                                               deny_deprecated: true,
+                                               with_sections: true) =>
+        { tags: editable_tags, sections: }
     TagVersioning.record_tag_snapshots!(editable_tags, created_by_user: current_user)
 
     readonly_tags = post.tags.nico.to_a
 
     tags = readonly_tags + editable_tags
-    tags = Tag.expand_parent_tags(tags)
+    tags = Tag.expand_parent_tags(tags).reject(&:deprecated?)
 
-    sync_post_tags!(post, tags)
+    post.video_ms = tags.any? { _1.id == Tag.video.id } ? snapshot[:video_ms] : nil
+    validate_video_sections!(post.video_ms, sections)
+    post.save!
+    sync_post_tags!(post, tags, sections)
     sync_parent_posts!(post, snapshot[:parent_post_ids])
 
     PostVersionRecorder.record!(post:, event_type: :update, created_by_user: current_user)
   end
 
   def merge_post_snapshots base_snapshot, current_snapshot, incoming_snapshot
-    [:title, :original_created_from, :original_created_before].map {
+    [:title, :video_ms, :original_created_from, :original_created_before].map {
       [_1, merge_scalar_snapshot_value(base_snapshot[_1],
                                        current_snapshot[_1],
                                        incoming_snapshot[_1])]
@@ -681,4 +758,44 @@ class PostsController < ApplicationController
       render_validation_error record
     end
   end
+
+  def normalise_video_ms tags, video_ms_param: params[:video_ms], duration_param: params[:duration]
+    return nil unless tags.any? { _1.id == Tag.video.id }
+
+    if video_ms_param.present?
+      video_ms = Integer(video_ms_param, exception: false)
+      raise VideoMsParseError unless video_ms&.positive?
+
+      return video_ms
+    end
+
+    return nil if duration_param.blank?
+
+    video_ms = Tag.time_to_ms!(duration_param.to_s, tag_name: '動画時間')
+    raise VideoMsParseError unless video_ms.positive?
+
+    video_ms
+  rescue Tag::SectionLiteralParseError
+    raise VideoMsParseError
+  end
+
+  def validate_video_sections! video_ms, sections
+    return unless video_ms
+
+    sections.each_value do |ranges|
+      ranges.each do |begin_ms, end_ms|
+        if begin_ms >= video_ms
+          post = Post.new
+          post.errors.add :video_ms, 'タグ区間の開始が動画時間以上です．'
+          raise ActiveRecord::RecordInvalid, post
+        end
+
+        if end_ms && end_ms > video_ms
+          post = Post.new
+          post.errors.add :video_ms, 'タグ区間の終端が動画時間を超えてゐます．'
+          raise ActiveRecord::RecordInvalid, post
+        end
+      end
+    end
+  end
 end

backend/app/controllers/preview_controller.rb

@@ -1,50 +1,57 @@
 class PreviewController < ApplicationController
+  before_action :require_member!
+
   def title
-    # TODO: # 既知サイトなら決まったフォーマットで title 取得するやぅに．
-    return head :unauthorized unless current_user
+    return render_bad_request('URL は必須です．') if params[:url].blank?
 
-    url = params[:url]
-    return render_bad_request('URL は必須です．') unless url.present?
-
-    unless url.start_with?(/http(s)?:\/\//)
-      url = 'http://' + url
-    end
-
-    html = URI.open(url, open_timeout: 5, read_timeout: 5).read
-    doc = Nokogiri::HTML.parse(html)
-    title = doc.at('title')&.text&.strip
-
-    render json: { title: title }
-  rescue => e
+    render json: { title: Preview::ThumbnailFetcher.title(params[:url]) }
+  rescue Preview::UrlSafety::UnsafeUrl => e
     render_bad_request(e.message)
+  rescue Preview::HttpFetcher::FetchTimeout => e
+    render_preview_error(e.message, :gateway_timeout)
+  rescue Preview::HttpFetcher::ResponseTooLarge => e
+    render_preview_error(e.message, :payload_too_large)
+  rescue Preview::HttpFetcher::FetchFailed => e
+    render_preview_error(e.message, :bad_gateway)
   end
 
   def thumbnail
-    # TODO: 既知ドメインであれば指定のアドレスからサムネールを取得するやぅにする．
+    return render_bad_request('URL は必須です．') if params[:url].blank?
 
+    image = MiniMagick::Image.read(Preview::ThumbnailFetcher.fetch(params[:url]))
+    image.auto_orient
+    image.resize '180x180>'
+    image.format 'png'
+    width, height = image.dimensions
+    raise Preview::ThumbnailFetcher::GenerationFailed, 'サムネール画像の変換に失敗しました．' if width > 180 || height > 180
+
+    send_data image.to_blob, type: 'image/png', disposition: 'inline'
+  rescue Preview::UrlSafety::UnsafeUrl => e
+    render_bad_request(e.message)
+  rescue Preview::HttpFetcher::FetchTimeout => e
+    render_preview_error(e.message, :gateway_timeout)
+  rescue Preview::HttpFetcher::ResponseTooLarge => e
+    render_preview_error(e.message, :payload_too_large)
+  rescue Preview::HttpFetcher::FetchFailed => e
+    render_preview_error(e.message, :bad_gateway)
+  rescue Preview::ThumbnailFetcher::GenerationFailed, MiniMagick::Error => e
+    render_unprocessable_entity(e.message)
+  end
+
+  private
+
+  def require_member!
     return head :unauthorized unless current_user
+    return if current_user.gte_member?
 
-    url = params[:url]
-    return render_bad_request('URL は必須です．') if url.blank?
+    head :forbidden
+  end
 
-    unless url.start_with?(/http(s)?:\/\//)
-      url = 'http://' + url
-    end
-
-    path = Rails.root.join('tmp', "thumb_#{ SecureRandom.hex }.png")
-    system("node #{ Rails.root }/lib/screenshot.js #{ Shellwords.escape(url) } #{ path }")
-
-    if File.exist?(path)
-      image = MiniMagick::Image.open(path)
-      image.resize '180x180'
-      File.delete(path) rescue nil
-      send_file image.path, type: 'image/png', disposition: 'inline'
-    else
-      render json: { type: 'internal_server_error',
-                     message: 'サムネールを生成できませんでした．',
-                     errors: { },
-                     base_errors: ['サムネールを生成できませんでした．'] },
-             status: :internal_server_error
-    end
+  def render_preview_error(message, status)
+    render json: { type: status.to_s,
+                   message:,
+                   errors: { },
+                   base_errors: [message] },
+           status:
   end
 end

backend/app/controllers/tag_versions_controller.rb

@@ -17,6 +17,7 @@ class TagVersionsController < ApplicationController
               AND prev.version_no = tag_versions.version_no - 1
         SQL
       .select('tag_versions.*', 'prev.name AS prev_name', 'prev.category AS prev_category',
+              'prev.deprecated_at AS prev_deprecated_at',
               'prev.aliases AS prev_aliases', 'prev.parent_tag_ids AS prev_parent_tag_ids')
     q = q.where('tag_versions.tag_id = ?', tag_id) if tag_id
 
@@ -62,6 +63,8 @@ class TagVersionsController < ApplicationController
         event_type: row.event_type,
         name: { current: row.name, prev: row.attributes['prev_name'] },
         category: { current: row.category, prev: row.attributes['prev_category'] },
+        deprecated_at: { current: row.deprecated_at&.iso8601,
+                         prev: row.attributes['prev_deprecated_at']&.iso8601 },
         aliases: build_version_values(cur_aliases, prev_aliases, key: :name),
         parent_tags:,
         created_at: row.created_at.iso8601,

backend/app/controllers/tags_controller.rb

@@ -1,5 +1,6 @@
 require 'net/http'
 require 'uri'
+require 'set'
 
 
 class TagsController < ApplicationController
@@ -14,6 +15,8 @@ class TagsController < ApplicationController
     post_count_between[1] = nil if post_count_between[1] < 0
     created_between = params[:created_from].presence, params[:created_to].presence
     updated_between = params[:updated_from].presence, params[:updated_to].presence
+    deprecated_given = params.key?(:deprecated)
+    deprecated = bool?(:deprecated)
 
     order = params[:order].to_s.split(':', 2).map(&:strip)
     unless order[0].in?(['name', 'category', 'post_count', 'created_at', 'updated_at'])
@@ -48,6 +51,9 @@ class TagsController < ApplicationController
     q = q.where('tags.created_at <= ?', created_between[1]) if created_between[1]
     q = q.where('tags.updated_at >= ?', updated_between[0]) if updated_between[0]
     q = q.where('tags.updated_at <= ?', updated_between[1]) if updated_between[1]
+    if deprecated_given
+      q = deprecated ? q.where.not(deprecated_at: nil) : q.where(deprecated_at: nil)
+    end
 
     sort_sql =
         case order[0]
@@ -76,39 +82,20 @@ class TagsController < ApplicationController
   def with_depth
     parent_tag_id = params[:parent].to_i
     parent_tag_id = nil if parent_tag_id <= 0
+    material_filter = material_filter_param(default: 'any')
+
+    graph = build_with_depth_graph(material_filter)
 
     tag_ids =
         if parent_tag_id
-          TagImplication.where(parent_tag_id:).select(:tag_id)
+          visible_child_tag_ids(parent_tag_id, graph)
         else
-          Tag.where.not(id: TagImplication.select(:tag_id)).select(:id)
+          visible_root_tag_ids(graph)
         end
 
-    tags =
-        Tag
-        .joins(:tag_name)
-        .includes(:tag_name, :materials, tag_name: :wiki_page)
-        .where(category: [:meme, :character, :material])
-        .where(id: tag_ids)
-        .order('tag_names.name')
-        .distinct
-        .to_a
-
-    has_children_tag_ids =
-        if tags.empty?
-          []
-        else
-          TagImplication
-              .joins(:tag)
-              .where(parent_tag_id: tags.map(&:id),
-                     tags: { category: [:meme, :character, :material] })
-              .distinct
-              .pluck(:parent_tag_id)
-        end
-
-    render json: tags.map { |tag|
-      TagRepr.base(tag).merge(has_children: has_children_tag_ids.include?(tag.id), children: [])
-    }
+    render json: tag_ids
+                 .sort_by { |tag_id| graph[:tags_by_id][tag_id][:name] }
+                 .map { |tag_id| with_depth_lightweight_repr(tag_id, graph) }
   end
 
   def autocomplete
@@ -133,6 +120,7 @@ class TagsController < ApplicationController
 
     base = Tag.joins(:tag_name)
               .includes(:tag_name, :materials, tag_name: :wiki_page)
+              .where(deprecated_at: nil)
     base = base.where('tags.post_count > 0') if present_only
 
     canonical_hit =
@@ -232,13 +220,16 @@ class TagsController < ApplicationController
   def materials_by_name
     name = params[:name].to_s.strip
     return render_bad_request('name は必須です．') if name.blank?
+    material_filter = material_filter_param(default: 'any')
 
     tag = Tag.joins(:tag_name)
              .includes(:tag_name, :materials, tag_name: :wiki_page)
              .find_by(tag_names: { name: })
     return head :not_found unless tag
 
-    render json: build_tag_children(tag)
+    graph = build_with_depth_graph(material_filter)
+
+    render json: build_tag_children(tag, graph:)
   end
 
   def update_all
@@ -252,18 +243,21 @@ class TagsController < ApplicationController
     category = params[:category].to_s.strip
     return render_unprocessable_entity('名前は必須です．', field: :name) if name.blank?
     return render_unprocessable_entity('カテゴリは必須です．', field: :category) if category.blank?
+    return render_unprocessable_entity '廃止状態は必須です．', field: :deprecated unless params.key?(:deprecated)
 
-    if name != tag.name &&
-        tag.in?([Tag.tagme, Tag.bot, Tag.no_deerjikist, Tag.video, Tag.niconico])
-      return render_unprocessable_entity('システム・タグの名称は変更できません．', field: :name)
-    end
-
-    if tag.nico? || category == 'nico'
-      return render_unprocessable_entity('ニコタグは変更できません．', field: :category)
-    end
+    return unless validate_tag_rename(tag, name)
 
     alias_names = params[:aliases].to_s.split.uniq
     parent_names = params[:parent_tags].to_s.split.uniq
+    deprecated = bool?(:deprecated)
+
+    if tag.nico? && deprecated
+      return render_unprocessable_entity 'ニコタグは廃止できません．', field: :deprecated
+    end
+
+    if tag.nico? || category == 'nico'
+      return render_unprocessable_entity 'ニコタグは変更できません．', field: :category
+    end
 
     ApplicationRecord.transaction do
       TagVersioning.ensure_snapshot!(tag, created_by_user: current_user)
@@ -272,8 +266,12 @@ class TagsController < ApplicationController
       name_changed = name != old_name
       wiki_page = tag.tag_name.wiki_page if name_changed
 
-      tag.update!(category:)
-      tag.tag_name.update!(name:)
+      if tag.deprecated? == deprecated
+        tag.update!(category:)
+      else
+        tag.update!(category:, deprecated_at: deprecated ? Time.current : nil)
+      end
+      rename_tag_name!(tag, name) if name_changed
 
       alias_names << old_name if name_changed
       alias_names.delete(name)
@@ -300,11 +298,19 @@ class TagsController < ApplicationController
 
     name = params[:name].presence
     category = params[:category].presence
+    deprecated_given = params.key?(:deprecated)
+    deprecated = bool?(:deprecated)
 
     tag = Tag.find(params[:id])
 
+    if tag.nico? && deprecated_given && deprecated
+      return render_unprocessable_entity 'ニコタグは廃止できません．', field: :deprecated
+    end
+
+    return unless validate_tag_rename(tag, name)
+
     if tag.nico? || (category.present? && category == 'nico')
-      return render_unprocessable_entity('ニコタグは変更できません．', field: :category)
+      return render_unprocessable_entity 'ニコタグは変更できません．', field: :category
     end
 
     ApplicationRecord.transaction do
@@ -314,8 +320,11 @@ class TagsController < ApplicationController
       name_changed = name.present? && name != old_name
       wiki_page = tag.tag_name.wiki_page if name_changed
 
-      tag.tag_name.update!(name:) if name.present?
+      rename_tag_name!(tag, name) if name_changed
       tag.update!(category:) if category.present?
+      if deprecated_given && tag.deprecated? != deprecated
+        tag.update!(deprecated_at: deprecated ? Time.current : nil)
+      end
 
       tag.reload
 
@@ -332,18 +341,178 @@ class TagsController < ApplicationController
 
   private
 
-  def build_tag_children tag
+  def material_filter_param default:
+    value = params[:material_filter].to_s.presence
+    return default unless ['present', 'missing', 'any'].include?(value)
+
+    value
+  end
+
+  def build_with_depth_graph material_filter
+    children_by_parent_id = Hash.new { |h, k| h[k] = [] }
+    parent_ids_by_child_id = Hash.new { |h, k| h[k] = [] }
+
+    TagImplication.pluck(:parent_tag_id, :tag_id).each do |parent_id, child_id|
+      children_by_parent_id[parent_id] << child_id
+      parent_ids_by_child_id[child_id] << parent_id
+    end
+
+    tag_ids = (children_by_parent_id.keys +
+               parent_ids_by_child_id.keys +
+               Tag.where(category: ['meme', 'character', 'material']).pluck(:id)).uniq
+
+    material_tag_ids = Material.unscoped.kept.where.not(tag_id: nil).distinct.pluck(:tag_id).to_set
+
+    tags_by_id = Tag.joins(:tag_name)
+                    .where(id: tag_ids)
+                    .pluck('tags.id', 'tag_names.name', 'tags.category', 'tags.deprecated_at')
+                    .each_with_object({ }) do |(id, name, category, deprecated_at), h|
+      h[id] = { name:, category:, deprecated: deprecated_at.present?,
+                has_material: material_tag_ids.include?(id) }
+    end
+
+    { children_by_parent_id:, parent_ids_by_child_id:, tags_by_id:,
+      visible_child_tag_ids_by_parent_id: { },
+      visible_subtree_by_tag_id: { },
+      material_filter: }
+  end
+
+  def visible_root_tag_ids graph
+    root_ids = Set.new
+
+    graph[:tags_by_id].each do |tag_id, attrs|
+      next unless visible_root_tag?(tag_id, graph)
+      next unless visible_subtree?(tag_id, graph)
+
+      if attrs[:deprecated]
+        collect_visible_child_tag_ids(tag_id, graph, root_ids, Set.new)
+      else
+        root_ids << tag_id
+      end
+    end
+
+    root_ids.to_a
+  end
+
+  def visible_root_tag? tag_id, graph
+    seen = Set.new([tag_id])
+    stack = graph[:parent_ids_by_child_id][tag_id].dup
+
+    until stack.empty?
+      parent_id = stack.pop
+      next if seen.include?(parent_id)
+
+      seen << parent_id
+
+      parent = graph[:tags_by_id][parent_id]
+      next unless parent
+
+      return false unless parent[:deprecated]
+
+      stack.concat(graph[:parent_ids_by_child_id][parent_id])
+    end
+
+    true
+  end
+
+  def visible_child_tag_ids parent_tag_id, graph
+    cache = graph[:visible_child_tag_ids_by_parent_id]
+    return cache[parent_tag_id] if cache.key?(parent_tag_id)
+
+    visible_ids = Set.new
+
+    graph[:children_by_parent_id][parent_tag_id].each do |child_tag_id|
+      collect_visible_child_tag_ids(child_tag_id, graph, visible_ids, Set.new([parent_tag_id]))
+    end
+
+    cache[parent_tag_id] = visible_ids.to_a
+  end
+
+  def collect_visible_child_tag_ids tag_id, graph, visible_ids, seen
+    return if seen.include?(tag_id)
+
+    seen = seen.dup << tag_id
+    tag = graph[:tags_by_id][tag_id]
+    return unless tag
+
+    if tag[:deprecated]
+      graph[:children_by_parent_id][tag_id].each do |child_tag_id|
+        collect_visible_child_tag_ids(child_tag_id, graph, visible_ids, seen)
+      end
+      return
+    end
+
+    if with_depth_visible_tag?(tag, graph[:material_filter])
+      visible_ids << tag_id
+      return
+    end
+
+    visible_ids << tag_id if graph[:children_by_parent_id][tag_id].any? { |child_tag_id|
+      visible_subtree?(child_tag_id, graph)
+    }
+  end
+
+  def with_depth_visible_tag? tag, material_filter
+    return false unless tag[:category].in?(['meme', 'character', 'material']) && !tag[:deprecated]
+
+    case material_filter
+    when 'present'
+      tag[:has_material]
+    when 'missing'
+      !tag[:has_material]
+    else
+      true
+    end
+  end
+
+  def visible_subtree? tag_id, graph
+    cache = graph[:visible_subtree_by_tag_id]
+    return cache[tag_id] if cache.key?(tag_id)
+
+    tag = graph[:tags_by_id][tag_id]
+    return cache[tag_id] = false unless tag
+
+    if tag[:deprecated]
+      return cache[tag_id] =
+                 graph[:children_by_parent_id][tag_id].any? { |child_tag_id|
+                   visible_subtree?(child_tag_id, graph)
+                 }
+    end
+
+    cache[tag_id] =
+        with_depth_visible_tag?(tag, graph[:material_filter]) ||
+        graph[:children_by_parent_id][tag_id].any? { |child_tag_id|
+          visible_subtree?(child_tag_id, graph)
+        }
+  end
+
+  def with_depth_lightweight_repr tag_id, graph
+    tag = graph[:tags_by_id][tag_id]
+
+    { id: tag_id,
+      name: tag[:name],
+      category: tag[:category],
+      deprecated: tag[:deprecated],
+      has_material: tag[:has_material],
+      has_children: visible_child_tag_ids(tag_id, graph).present?,
+      children: [] }
+  end
+
+  def build_tag_children tag, graph: nil
     material = tag.materials.first
-    file = nil
-    content_type = nil
-    if material&.file&.attached?
-      file = rails_storage_proxy_url(material.file, only_path: false)
-      content_type = material.file.blob.content_type
+    tag_graph = graph && graph[:tags_by_id][tag.id]
+    material =
+        nil if tag_graph && !with_depth_visible_tag?(tag_graph, graph[:material_filter])
+
+    children = tag.children.sort_by(&:name)
+    if graph
+      children = children.filter { |child_tag| visible_subtree?(child_tag.id, graph) }
     end
 
     TagRepr.base(tag).merge(
-        children: tag.children.sort_by { _1.name }.map { build_tag_children(_1) },
-        material: material.as_json&.merge(file:, content_type:))
+        children: children.map { build_tag_children(_1, graph:) },
+        has_material: tag_graph ? tag_graph[:has_material] : material.present?,
+        material: material && MaterialRepr.base(material, host: request.base_url))
   end
 
   def record_tag_version! tag, event_type:, created_by_user:, name_changed: false, wiki_page: nil
@@ -365,6 +534,67 @@ class TagsController < ApplicationController
         created_by_user:)
   end
 
+  def validate_tag_rename tag, name
+    return true if name.blank? || name == tag.name
+
+    if tag.in?([Tag.tagme, Tag.bot, Tag.no_deerjikist, Tag.video, Tag.niconico])
+      render_unprocessable_entity 'システム・タグの名称は変更できません．', field: :name
+      return false
+    end
+
+    target_tag_name = TagName.with_discarded.find_by(name:)
+    return true if target_tag_name.nil?
+    return true if target_tag_name.canonical_id?
+
+    render_unprocessable_entity 'その名前は既に使はれてゐます．', field: :name
+    false
+  end
+
+  def rename_tag_name! tag, name
+    return if name == tag.name
+
+    current_tag_name = tag.tag_name
+    target_tag_name = TagName.with_discarded.find_by(name:)
+
+    if target_tag_name.nil?
+      current_tag_name.update!(name:)
+      return
+    end
+
+    promote_tag_alias!(
+        tag,
+        current_tag_name:,
+        promoted_tag_name: target_tag_name)
+  end
+
+  def promote_tag_alias! tag, current_tag_name:, promoted_tag_name:
+    old_owner_tag = promoted_tag_name.canonical&.tag
+
+    if old_owner_tag && old_owner_tag != tag
+      TagVersioning.ensure_snapshot!(old_owner_tag, created_by_user: current_user)
+    end
+
+    promoted_tag_name.undiscard! if promoted_tag_name.discarded?
+    promoted_tag_name.update!(canonical: nil)
+
+    TagName.with_discarded
+           .where(canonical_id: current_tag_name.id)
+           .where.not(id: promoted_tag_name.id)
+           .find_each do |alias_tag_name|
+      alias_tag_name.update!(canonical: promoted_tag_name)
+    end
+
+    current_tag_name.wiki_page&.update!(tag_name: promoted_tag_name)
+    tag.update!(tag_name: promoted_tag_name)
+    current_tag_name.association(:wiki_page).reset
+    current_tag_name.association(:tag).reset
+    current_tag_name.reload.update!(canonical: promoted_tag_name)
+
+    return unless old_owner_tag && old_owner_tag != tag
+
+    record_tag_version!(old_owner_tag.reload, event_type: :update, created_by_user: current_user)
+  end
+
   def update_aliases! tag, alias_names
     alias_names = alias_names.uniq
 

backend/app/controllers/user_settings_controller.rb

@@ -0,0 +1,61 @@
+class UserSettingsController < ApplicationController
+  wrap_parameters false
+
+  def show
+    return head :unauthorized unless current_user
+
+    render json: current_setting.serializable_hash
+  end
+
+  def update
+    return head :unauthorized unless current_user
+
+    raw_attributes = editable_raw_attributes
+    field_errors = validate_raw_attributes(raw_attributes)
+    return render_validation_error fields: field_errors if field_errors.present?
+
+    setting = current_setting
+    setting.assign_attributes(raw_attributes)
+
+    if setting.save
+      render json: setting.serializable_hash, status: :ok
+    else
+      render_validation_error setting
+    end
+  end
+
+  private
+
+  def current_setting
+    Setting.find_or_create_by!(user: current_user) do |setting|
+      setting.assign_attributes(Setting.defaults)
+    end
+  rescue ActiveRecord::RecordNotUnique
+    Setting.find_by!(user: current_user)
+  end
+
+  def editable_raw_attributes
+    request.request_parameters.slice(*Setting::EDITABLE_ATTRIBUTES)
+  end
+
+  def validate_raw_attributes raw_attributes
+    raw_attributes.each_with_object({ }) do |(key, value), errors|
+      next if value_matches_type?(key, value)
+
+      errors[key.to_sym] = ['値の型が不正です．']
+    end
+  end
+
+  def value_matches_type? key, value
+    case Setting::TYPE_BY_ATTRIBUTE.fetch(key)
+    when :string
+      value.is_a?(String)
+    when :integer
+      value.is_a?(Integer)
+    when :boolean
+      value == true || value == false
+    else
+      false
+    end
+  end
+end

backend/app/controllers/user_theme_slots_controller.rb

@@ -0,0 +1,38 @@
+class UserThemeSlotsController < ApplicationController
+  wrap_parameters false
+
+  def index
+    return head :unauthorized unless current_user
+
+    render json: current_user
+                 .theme_slots
+                 .order(:base_theme, :slot_no)
+                 .map { |slot| slot.serializable_hash }
+  end
+
+  def update
+    return head :unauthorized unless current_user
+
+    base_theme = params[:base_theme].to_s
+    slot_no = params[:slot_no].to_i
+    tokens = params[:tokens]
+
+    unless UserThemeSlot::BASE_THEMES.include?(base_theme)
+      return render_validation_error fields: { base_theme: ['値が不正です．'] }
+    end
+    unless UserThemeSlot::SLOT_NOS.include?(slot_no)
+      return render_validation_error fields: { slot_no: ['値が不正です．'] }
+    end
+    unless tokens.is_a?(ActionController::Parameters) || tokens.is_a?(Hash)
+      return render_validation_error fields: { tokens: ['JSON object で指定してください．'] }
+    end
+
+    slot = UserThemeSlot.find_or_initialize_by(user: current_user,
+                                               base_theme:,
+                                               slot_no:)
+    slot.tokens = tokens.is_a?(ActionController::Parameters) ? tokens.to_unsafe_h : tokens
+    slot.save!
+
+    render json: slot.serializable_hash, status: :ok
+  end
+end

backend/app/controllers/wiki_pages_controller.rb

@@ -4,17 +4,18 @@ class WikiPagesController < ApplicationController
   def index
     title = params[:title].to_s.strip
     if title.blank?
-      return render json: WikiPageRepr.base(WikiPage.joins(:tag_name).includes(:tag_name))
+      return render json: WikiPageRepr.base(
+          WikiPage.joins(:tag_name).includes(tag_name: :tag))
     end
 
-    q = WikiPage.joins(:tag_name).includes(:tag_name)
+    q = WikiPage.joins(:tag_name).includes(tag_name: :tag)
         .where('tag_names.name LIKE ?', "%#{ WikiPage.sanitize_sql_like(title) }%")
     render json: WikiPageRepr.base(q.limit(20))
   end
 
   def show
     page = WikiPage.joins(:tag_name)
-                   .includes(:tag_name)
+                   .includes(tag_name: :tag)
                    .find_by(id: params[:id])
     render_wiki_page_or_404 page
   end
@@ -22,7 +23,7 @@ class WikiPagesController < ApplicationController
   def show_by_title
     title = params[:title].to_s.strip
     page = WikiPage.joins(:tag_name)
-                   .includes(:tag_name)
+                   .includes(tag_name: :tag)
                    .find_by(tag_name: { name: title })
     render_wiki_page_or_404 page
   end
@@ -51,7 +52,7 @@ class WikiPagesController < ApplicationController
     from = params[:from].presence
     to = params[:to].presence
 
-    page = WikiPage.joins(:tag_name).includes(:tag_name).find(id)
+    page = WikiPage.joins(:tag_name).includes(tag_name: :tag).find(id)
 
     from_rev = from && page.wiki_revisions.find(from)
     to_rev = to ? page.wiki_revisions.find(to) : page.current_revision
@@ -76,6 +77,7 @@ class WikiPagesController < ApplicationController
 
     render json: { wiki_page_id:      page.id,
                    title:             page.title,
+                   deprecated_at:     page.deprecated_at,
                    older_revision_id: from_rev&.id,
                    newer_revision_id: to_rev.id,
                    diff:              diff_json }
@@ -157,7 +159,7 @@ class WikiPagesController < ApplicationController
   def changes
     id = params[:id].presence
     q = WikiRevision.joins(wiki_page: :tag_name)
-                    .includes(:created_user, wiki_page: :tag_name)
+                    .includes(:created_user, wiki_page: { tag_name: :tag })
                     .order(id: :desc)
     q = q.where(wiki_page_id: id) if id
 
@@ -165,7 +167,9 @@ class WikiPagesController < ApplicationController
       { revision_id:  rev.id,
         pred:         rev.base_revision_id,
         succ:         nil,
-        wiki_page:    { id: rev.wiki_page_id, title: rev.wiki_page.title },
+        wiki_page:    { id: rev.wiki_page_id,
+                        title: rev.wiki_page.title,
+                        deprecated_at: rev.wiki_page.deprecated_at },
         user:         rev.created_user && { id: rev.created_user.id, name: rev.created_user.name },
         kind:         rev.kind,
         message:      rev.message,

backend/app/models/material.rb

@@ -1,6 +1,9 @@
 class Material < ApplicationRecord
   include MyDiscard
 
+  SOURCE_KINDS = ['uri', 'google_drive_path', 'google_drive_file',
+                  'legacy_drive_path'].freeze
+
   default_scope -> { kept }
 
   belongs_to :parent, class_name: 'Material', optional: true
@@ -10,9 +13,18 @@ class Material < ApplicationRecord
   belongs_to :created_by_user, class_name: 'User', optional: true
   belongs_to :updated_by_user, class_name: 'User', optional: true
 
-  has_one_attached :file, dependent: :purge
+  has_many :material_versions, dependent: :destroy
+  has_many :material_export_items, dependent: :destroy
 
-  validates :tag_id, presence: true, uniqueness: true
+  has_one_attached :file, dependent: :purge
+  has_one_attached :thumbnail, dependent: :purge
+
+  before_validation :assign_normalized_source_key
+
+  validates :tag_id, uniqueness: true, allow_nil: true
+  validates :source_kind,
+            inclusion: { in: SOURCE_KINDS },
+            allow_blank: true
 
   validate :file_must_be_attached
   validate :tag_must_be_material_category
@@ -23,8 +35,37 @@ class Material < ApplicationRecord
     file.blob.content_type
   end
 
+  def file_byte_size
+    return nil unless file&.attached?
+
+    file.blob.byte_size
+  end
+
+  def file_filename
+    return nil unless file&.attached?
+
+    file.blob.filename.to_s
+  end
+
+  def snapshot_export_paths
+    material_export_items.order(:profile).pluck(:profile, :export_path).to_h
+  end
+
   private
 
+  def assign_normalized_source_key
+    if source_kind.blank?
+      self.normalized_source_key = nil
+      return
+    end
+
+    self.normalized_source_key =
+        MaterialSyncSuppression.normalize_source_key(source_kind:,
+                                                     source_uri:,
+                                                     drive_path: source_path,
+                                                     drive_file_id: source_file_id)
+  end
+
   def file_must_be_attached
     return if url.present? || file.attached?
 

backend/app/models/material_export_item.rb

@@ -0,0 +1,48 @@
+class MaterialExportItem < ApplicationRecord
+  VALID_PROFILES = ['legacy_drive'].freeze
+
+  belongs_to :material
+  belongs_to :created_by_user, class_name: 'User', optional: true
+
+  validates :profile, presence: true, inclusion: { in: VALID_PROFILES }
+  validates :export_path, presence: true, uniqueness: { scope: :profile }
+  validates :material_id, uniqueness: { scope: :profile }
+  validate :export_path_must_be_relative_safe_path
+
+  scope :enabled, -> { where(enabled: true) }
+
+  private
+
+  def export_path_must_be_relative_safe_path
+    return if export_path.blank?
+
+    if export_path.start_with?('/')
+      errors.add(:export_path, '絶対パスは使へません．')
+    end
+
+    if export_path.match?(/\A[A-Za-z]:\//)
+      errors.add(:export_path, '絶対パスは使へません．')
+    end
+
+    if export_path.include?('\\')
+      errors.add(:export_path, '/ 区切りで指定してください．')
+    end
+
+    if export_path.include?("\0")
+      errors.add(:export_path, 'NUL は使へません．')
+    end
+
+    parts = export_path.split('/')
+    if export_path.include?('//')
+      errors.add(:export_path, '空の path segment は使へません．')
+    end
+
+    if parts.any? { |part| part.in?(['.', '..']) }
+      errors.add(:export_path, '.. は使へません．')
+    end
+
+    if export_path.end_with?('/')
+      errors.add(:export_path, 'directory path は使へません．')
+    end
+  end
+end

backend/app/models/material_import_block.rb

@@ -0,0 +1,29 @@
+class MaterialImportBlock < ApplicationRecord
+  MATCH_KINDS = ['sha256', 'exact_path', 'path_prefix', 'manual'].freeze
+  REASONS = [
+    'copyright_high_risk',
+    'copyright_takedown',
+    'adult_or_sensitive',
+    'personal_information',
+    'malware_or_dangerous_file',
+    'duplicate_or_low_quality',
+    'source_owner_request',
+    'other'
+  ].freeze
+
+  belongs_to :created_by_user, class_name: 'User', optional: true
+
+  validates :match_kind, presence: true, inclusion: { in: MATCH_KINDS }
+  validates :reason, presence: true, inclusion: { in: REASONS }
+  validates :sha256, length: { is: 64 }, allow_blank: true
+  validate :match_value_must_be_present
+
+  private
+
+  def match_value_must_be_present
+    return if match_kind == 'manual'
+    return if sha256.present? || external_path_pattern.present?
+
+    errors.add(:base, 'sha256 または external_path_pattern は必須です．')
+  end
+end

backend/app/models/material_sync_source.rb

@@ -0,0 +1,45 @@
+class MaterialSyncSource < ApplicationRecord
+  SOURCE_KINDS = ['uri', 'google_drive_path', 'google_drive_file', 'legacy_drive_path'].freeze
+
+  belongs_to :created_by_user, class_name: 'User', optional: true
+  belongs_to :updated_by_user, class_name: 'User', optional: true
+
+  validates :name, presence: true
+  validates :source_kind,
+            presence: true,
+            inclusion: { in: SOURCE_KINDS }
+  validates :profile, presence: true, inclusion: { in: MaterialExportItem::VALID_PROFILES }
+  validate :source_value_must_be_present
+
+  scope :enabled, -> { where(enabled: true) }
+
+  def normalized_source_key
+    MaterialSyncSuppression.normalize_source_key(source_kind:,
+                                                 source_uri:,
+                                                 source_path:,
+                                                 source_file_id:)
+  end
+
+  private
+
+  def source_value_must_be_present
+    return if source_value_present?
+
+    errors.add(:base, '同期元を指定してください．')
+  end
+
+  def source_value_present?
+    case source_kind
+    when 'uri'
+      source_uri.present?
+    when 'google_drive_file'
+      source_file_id.present? || source_uri.present?
+    when 'google_drive_path'
+      source_file_id.present? || source_uri.present?
+    when 'legacy_drive_path'
+      source_path.present?
+    else
+      normalized_source_key.present?
+    end
+  end
+end

backend/app/models/material_sync_suppression.rb

@@ -0,0 +1,105 @@
+class MaterialSyncSuppression < ApplicationRecord
+  SOURCE_KINDS = [
+    'uri',
+    'google_drive_path',
+    'google_drive_path_prefix',
+    'google_drive_file',
+    'legacy_drive_path',
+    'legacy_drive_path_prefix'
+  ].freeze
+
+  REASONS = [
+    'copyright_high_risk',
+    'copyright_takedown',
+    'adult_or_sensitive',
+    'personal_information',
+    'malware_or_dangerous_file',
+    'duplicate_or_low_quality',
+    'source_owner_request',
+    'other'
+  ].freeze
+
+  belongs_to :created_by_user, class_name: 'User', optional: true
+
+  before_validation :assign_normalized_source_key
+
+  validates :source_kind, presence: true, inclusion: { in: SOURCE_KINDS }
+  validates :reason, presence: true, inclusion: { in: REASONS }
+  validates :normalized_source_key, presence: true, uniqueness: true
+  validate :source_value_must_be_present
+  validate :drive_path_must_be_safe_relative_path
+
+  def self.normalize_source_key source_kind:,
+                                source_uri: nil,
+                                drive_path: nil,
+                                drive_file_id: nil,
+                                source_path: nil,
+                                source_file_id: nil
+    kind = source_kind.to_s
+    value =
+        case kind
+        when 'uri'
+          source_uri.to_s.strip
+        when 'google_drive_path', 'google_drive_path_prefix',
+             'legacy_drive_path', 'legacy_drive_path_prefix'
+          (source_path || drive_path).to_s.strip.gsub(%r{/+}, '/')
+        when 'google_drive_file'
+          (source_file_id || drive_file_id).to_s.strip
+        else
+          ''
+        end
+
+    return nil if kind.blank? || value.blank?
+
+    "#{ kind }:#{ value }"
+  end
+
+  private
+
+  def assign_normalized_source_key
+    normalize_path_fields!
+    self.normalized_source_key =
+        self.class.normalize_source_key(source_kind:,
+                                        source_uri:,
+                                        drive_path:,
+                                        drive_file_id:)
+  end
+
+  def source_value_must_be_present
+    return if normalized_source_key.present?
+
+    errors.add(:base, '同期元を指定してください．')
+  end
+
+  def drive_path_must_be_safe_relative_path
+    return unless source_kind.in?(
+        ['google_drive_path', 'google_drive_path_prefix',
+         'legacy_drive_path', 'legacy_drive_path_prefix'])
+
+    value = drive_path.to_s
+    return if value.blank?
+
+    if value.start_with?('/') || value.match?(/\A[A-Za-z]:\//)
+      errors.add(:drive_path, '相対 path を指定してください．')
+    end
+    if value.start_with?('My Drive/', 'マイドライブ/')
+      errors.add(:drive_path, '同期元フォルダからの相対 path を指定してください．')
+    end
+    errors.add(:drive_path, 'NUL は使へません．') if value.include?("\0")
+    errors.add(:drive_path, '連続スラッシュは使へません．') if value.include?('//')
+    errors.add(:drive_path, '末尾スラッシュは使へません．') if value.end_with?('/')
+
+    parts = value.split('/')
+    if parts.any? { |part| part.in?(['.', '..']) }
+      errors.add(:drive_path, '. や .. は使へません．')
+    end
+  end
+
+  def normalize_path_fields!
+    return unless source_kind.in?(
+        ['google_drive_path', 'google_drive_path_prefix',
+         'legacy_drive_path', 'legacy_drive_path_prefix'])
+
+    self.drive_path = drive_path.to_s.tr('\\', '/').strip.presence
+  end
+end

backend/app/models/material_version.rb

@@ -0,0 +1,17 @@
+class MaterialVersion < ApplicationRecord
+  EVENT_TYPE_MAP = { create: 'create',
+                     update: 'update',
+                     discard: 'discard',
+                     restore: 'restore' }.freeze
+
+  include VersionRecord
+
+  belongs_to :material
+  belongs_to :tag, optional: true
+  belongs_to :parent, class_name: 'Material', optional: true
+  belongs_to :updated_by_user, class_name: 'User', optional: true
+
+  def export_paths_hash
+    export_paths_json || {}
+  end
+end

backend/app/models/post.rb

@@ -1,5 +1,19 @@
 class Post < ApplicationRecord
   require 'mini_magick'
+  require 'stringio'
+
+  def self.resized_thumbnail_attachment(upload)
+    upload.rewind
+    image = MiniMagick::Image.read(upload.read)
+    image.resize '180x180'
+    image.format 'jpg'
+
+    { io: StringIO.new(image.to_blob),
+      filename: 'resized_thumbnail.jpg',
+      content_type: 'image/jpeg' }
+  ensure
+    upload.rewind
+  end
 
   belongs_to :uploaded_user, class_name: 'User', optional: true
 
@@ -7,6 +21,8 @@ class Post < ApplicationRecord
   has_many :active_post_tags, -> { kept }, class_name: 'PostTag', inverse_of: :post
   has_many :post_tags_with_discarded, -> { with_discarded }, class_name: 'PostTag'
   has_many :tags, through: :active_post_tags
+  has_many :active_tags, -> { where(tags: { deprecated_at: nil }) },
+           through: :active_post_tags, source: :tag
 
   has_many :user_post_views, dependent: :delete_all
   has_many :post_similarities, dependent: :delete_all
@@ -41,9 +57,10 @@ class Post < ApplicationRecord
 
   attribute :version_no, :integer, default: 1
 
-  before_validation :normalise_url
+  before_validation :normalise_url, if: :will_save_change_to_url?
 
   validates :url, presence: true, uniqueness: true
+  validates :video_ms, numericality: { only_integer: true, greater_than: 0 }, allow_nil: true
 
   validate :validate_original_created_range
   validate :url_must_be_http_url
@@ -67,7 +84,42 @@ class Post < ApplicationRecord
     super(options).merge(thumbnail: nil)
   end
 
-  def snapshot_tag_names = tags.joins(:tag_name).order('tag_names.name').pluck('tag_names.name')
+  def snapshot_tag_names
+    post_tags
+        .kept
+        .joins(tag: :tag_name)
+        .includes(:sections, tag: :tag_name)
+        .order('tag_names.name')
+        .map do |post_tag|
+      name = post_tag.tag.tag_name.name
+      sections = post_tag.sections.sort_by(&:begin_ms)
+
+      next name if sections.empty?
+
+      "#{ name }#{ sections.map { Post.section_literal(_1) }.join }"
+    end
+  end
+
+  def self.section_literal section
+    "[#{ Post.ms_to_time(section.begin_ms) }-#{ section.end_ms ? Post.ms_to_time(section.end_ms) : '' }]"
+  end
+
+  def self.ms_to_time ms
+    total_s = ms / 1_000
+    s = total_s % 60
+    min = (total_s / 60) % 60
+    h = total_s / 3_600
+    remainder_ms = ms % 1_000
+
+    base =
+        if h.positive?
+          '%d:%02d:%02d' % [h, min, s]
+        else
+          '%d:%02d' % [min, s]
+        end
+
+    remainder_ms.positive? ? "#{ base }.#{ remainder_ms.to_s.rjust(3, '0') }" : base
+  end
 
   def snapshot_parent_post_ids = parents.order(:id).pluck(:id)
 
@@ -85,12 +137,7 @@ class Post < ApplicationRecord
   def resized_thumbnail!
     return unless thumbnail.attached?
 
-    image = MiniMagick::Image.read(thumbnail.download)
-    image.resize '180x180'
-    thumbnail.purge
-    thumbnail.attach(io:            File.open(image.path),
-                     filename:      'resized_thumbnail.jpg',
-                     content_type:  'image/jpeg')
+    thumbnail.attach(self.class.resized_thumbnail_attachment(StringIO.new(thumbnail.download)))
   end
 
   private
@@ -133,7 +180,7 @@ class Post < ApplicationRecord
 
     u.host = u.host.downcase if u.host
     u.path = u.path.sub(/\/\Z/, '') if u.path.present?
-    self.url = u.to_s
+    self.url = PostUrlSanitisationRule.sanitise(u.to_s)
   rescue URI::InvalidURIError
     ;
   end

backend/app/models/post_tag.rb

@@ -10,6 +10,12 @@ class PostTag < ApplicationRecord
   belongs_to :created_user, class_name: 'User', optional: true
   belongs_to :deleted_user, class_name: 'User', optional: true
 
+  has_many :sections, -> { order(:begin_ms) }, class_name: 'PostTagSection',
+                                               foreign_key: [:post_id, :tag_id],
+                                               primary_key: [:post_id, :tag_id],
+                                               dependent: :delete_all,
+                                               inverse_of: :post_tag
+
   validates :post_id, presence: true
   validates :tag_id, presence: true
   validates :post_id, uniqueness: {

backend/app/models/post_tag_section.rb

@@ -0,0 +1,20 @@
+class PostTagSection < ApplicationRecord
+  self.primary_key = :post_id, :tag_id, :begin_ms
+
+  belongs_to :post
+  belongs_to :tag
+
+  belongs_to :post_tag, -> { kept }, foreign_key: [:post_id, :tag_id],
+                                     primary_key: [:post_id, :tag_id],
+                                     inverse_of: :sections,
+                                     optional: true
+
+  validates :post_id, presence: true
+  validates :tag_id, presence: true
+
+  validates :begin_ms, presence: true,
+                       numericality: { only_integer: true, greater_than_or_equal_to: 0 }
+
+  validates :end_ms, numericality: { only_integer: true, greater_than: :begin_ms },
+                     allow_nil: true
+end

backend/app/models/post_url_sanitisation_rule.rb

@@ -0,0 +1,77 @@
+class PostUrlSanitisationRule < ApplicationRecord
+  include Discard::Model
+
+  class UrlConflictError < StandardError
+    attr_reader :conflicts
+
+    def initialize(conflicts)
+      @conflicts = conflicts
+      urls = conflicts.map { _1.fetch(:url) }.uniq.join(', ')
+      super("post URL sanitisation conflicts detected for #{ urls }")
+    end
+  end
+
+  self.primary_key = :priority
+
+  default_scope -> { kept }
+
+  validates :source_pattern, presence: true, uniqueness: true
+
+  validate :source_pattern_must_be_regexp
+
+  class << self
+    def sanitise(url) =
+        rules.reduce(url.dup) { |value, (pattern, replacement)| value.sub(pattern, replacement) }
+
+    def apply!
+      rewrites = Post.order(:id).pluck(:id, :url).map do |post_id, original_url|
+        { post_id:,
+          original_url:,
+          sanitised_url: sanitise(original_url) }
+      end
+
+      conflicts = rewrites
+                      .group_by { _1.fetch(:sanitised_url) }
+                      .values
+                      .filter { _1.size > 1 }
+                      .flatten
+                      .map { { url: _1.fetch(:sanitised_url),
+                               post_id: _1.fetch(:post_id),
+                               original_url: _1.fetch(:original_url) } }
+
+      raise UrlConflictError.new(conflicts) if conflicts.present?
+
+      changed = rewrites.filter { _1.fetch(:original_url) != _1.fetch(:sanitised_url) }
+      return if changed.empty?
+
+      token = SecureRandom.hex(6)
+
+      Post.transaction do
+        changed.each do |row|
+          Post.where(id: row.fetch(:post_id))
+              .update_all(url: temporary_url_for(row.fetch(:post_id), token))
+        end
+
+        changed.each do |row|
+          Post.where(id: row.fetch(:post_id))
+              .update_all(url: row.fetch(:sanitised_url))
+        end
+      end
+    end
+
+    private
+
+    def rules = kept.order(:priority).map { |r| [Regexp.new(r.source_pattern), r.replacement] }
+
+    def temporary_url_for(post_id, token) =
+        "https://post-url-sanitising.invalid/#{ token }/#{ post_id }"
+  end
+
+  private
+
+  def source_pattern_must_be_regexp
+    Regexp.new(source_pattern)
+  rescue RegexpError
+    errors.add :source_pattern, '変な正規表現だね〜（笑）'
+  end
+end

backend/app/models/post_version.rb

@@ -5,6 +5,7 @@ class PostVersion < ApplicationRecord
   belongs_to :parent, class_name: 'Post', optional: true
 
   validates :url, presence: true
+  validates :video_ms, numericality: { only_integer: true, greater_than: 0 }, allow_nil: true
 
   validate :validate_original_created_range
 

backend/app/models/setting.rb

@@ -1,7 +1,52 @@
 class Setting < ApplicationRecord
+  THEMES = ['system', 'light', 'dark'].freeze
+
+  # These remain in the typed settings schema to preserve existing backend
+  # work. The common `/users/settings` page currently surfaces only `theme`.
+  AUTO_FETCH_MODES = ['auto', 'manual', 'off'].freeze
+  WIKI_EDITOR_MODES = ['split', 'write', 'preview'].freeze
+
+  STRING_ATTRIBUTES = [
+    'theme',
+    'auto_fetch_title',
+    'auto_fetch_thumbnail',
+    'wiki_editor_mode',
+  ].freeze
+  INTEGER_ATTRIBUTES = [].freeze
+  BOOLEAN_ATTRIBUTES = [].freeze
+  EDITABLE_ATTRIBUTES =
+      (STRING_ATTRIBUTES + INTEGER_ATTRIBUTES + BOOLEAN_ATTRIBUTES).freeze
+  TYPE_BY_ATTRIBUTE = {
+    'theme' => :string,
+    'auto_fetch_title' => :string,
+    'auto_fetch_thumbnail' => :string,
+    'wiki_editor_mode' => :string,
+  }.freeze
+
   belongs_to :user
 
   validates :user_id, presence: true
-  validates :key, presence: true, length: { maximum: 255 }
-  validates :value, presence: true
+  validates :user_id, uniqueness: true
+
+  validates :theme, inclusion: { in: THEMES }
+  validates :auto_fetch_title, inclusion: { in: AUTO_FETCH_MODES }
+  validates :auto_fetch_thumbnail, inclusion: { in: AUTO_FETCH_MODES }
+  validates :wiki_editor_mode, inclusion: { in: WIKI_EDITOR_MODES }
+
+  def self.defaults
+    {
+      theme: 'system',
+      auto_fetch_title: 'manual',
+      auto_fetch_thumbnail: 'manual',
+      wiki_editor_mode: 'split',
+    }
+  end
+
+  def self.serializable_attributes
+    EDITABLE_ATTRIBUTES.map(&:to_sym)
+  end
+
+  def serializable_hash(options = nil)
+    super({ only: self.class.serializable_attributes }.merge(options || { }))
+  end
 end

backend/app/models/tag.rb

@@ -8,6 +8,25 @@ class Tag < ApplicationRecord
     ;
   end
 
+  class DeprecatedTagNormalisationError < ArgumentError
+    attr_reader :tag_names
+
+    def initialize tag_names
+      @tag_names = Array(tag_names)
+      super('deprecated tags are not allowed')
+    end
+  end
+
+  class SectionLiteralParseError < ArgumentError
+    attr_reader :tag_name, :literal
+
+    def initialize tag_name, literal
+      @tag_name = tag_name
+      @literal = literal
+      super("invalid section literal for tag #{ tag_name }: #{ literal }")
+    end
+  end
+
   has_many :post_tags, inverse_of: :tag
   has_many :active_post_tags, -> { kept }, class_name: 'PostTag', inverse_of: :tag
   has_many :post_tags_with_discarded, -> { with_discarded }, class_name: 'PostTag'
@@ -58,6 +77,7 @@ class Tag < ApplicationRecord
   validate :nico_tag_name_must_start_with_nico
   validate :tag_name_must_be_canonical
   validate :category_must_be_deerjikist_with_deerjikists
+  validate :nico_tags_cannot_be_deprecated
 
   scope :nico_tags, -> { nico }
 
@@ -77,6 +97,8 @@ class Tag < ApplicationRecord
     (self.tag_name ||= build_tag_name).name = val
   end
 
+  def deprecated? = deprecated_at?
+
   def has_wiki = wiki_page.present?
 
   def material_id = materials.first&.id
@@ -92,22 +114,61 @@ class Tag < ApplicationRecord
 
   def self.normalise_tags! tag_names, with_tagme: true,
                                       with_no_deerjikist: true,
-                                      deny_nico: true
+                                      deny_nico: true,
+                                      deny_deprecated: false,
+                                      with_sections: false
     if deny_nico && tag_names.any? { |n| n.downcase.start_with?('nico:') }
       raise NicoTagNormalisationError
     end
 
+    sections = { }
     tags = tag_names.map do |name|
+      raw_name = name
       pf, cat = CATEGORY_PREFIXES.find { |p, _| name.downcase.start_with?(p) } || ['', nil]
-      name = TagName.canonicalise(name.sub(/\A#{ pf }/i, '')).first
+
+      name = name.sub(/\A#{ pf }/i, '')
+
+      sections_by_tag = []
+      while (match = name.match(/\A(\S*?)\[([^\[\]\s]*)-([^\[\]\s]*)\](\S*)\z/))
+        name = "#{ match[1] }#{ match[4] }"
+        next if match[2].empty? && match[3].empty?
+
+        sections_by_tag << normalise_section_range!(
+            begin_raw: match[2],
+            end_raw: match[3],
+            tag_name: name)
+      end
+
+      if name.include?('[') || name.include?(']')
+        raise SectionLiteralParseError.new(raw_name, raw_name)
+      end
+
+      name = TagName.canonicalise(name).first
+
       find_or_create_by_tag_name!(name, category: (cat || :general)).tap do |tag|
+        if deny_deprecated && tag.deprecated?
+          raise DeprecatedTagNormalisationError, [tag.name]
+        end
+
         tag.update!(category: cat) if cat && tag.category != cat
+        next if sections_by_tag.empty?
+
+        sections[tag.id] ||= []
+        sections[tag.id].concat(sections_by_tag)
+        sections[tag.id] = merge_section_ranges(sections[tag.id])
+        sections.delete(tag.id) if sections[tag.id] == [[0, nil]]
       end
     end
 
     tags << Tag.tagme if with_tagme && tags.size < 10 && tags.none?(Tag.tagme)
     tags << Tag.no_deerjikist if with_no_deerjikist && tags.all? { |t| !(t.deerjikist?) }
-    tags.uniq(&:id)
+    tags.uniq!(&:id)
+
+    if with_sections
+      { tags:, sections: }
+    else
+      tags
+    end
   end
 
   def self.expand_parent_tags tags
@@ -133,6 +194,45 @@ class Tag < ApplicationRecord
     (result + tags).uniq { |t| t.id }
   end
 
+  def self.normalise_section_range! begin_raw:, end_raw:, tag_name:
+    begin_ms = begin_raw.empty? ? 0 : time_to_ms!(begin_raw, tag_name:)
+    end_ms = end_raw.empty? ? nil : time_to_ms!(end_raw, tag_name:)
+
+    if end_ms
+      begin_ms, end_ms = end_ms, begin_ms if begin_ms > end_ms
+      end_ms = begin_ms + 1 if begin_ms == end_ms
+    end
+
+    [begin_ms, end_ms]
+  end
+
+  def self.merge_section_ranges ranges
+    sorted_ranges = ranges.sort_by { |begin_ms, end_ms| [begin_ms, end_ms || Float::INFINITY] }
+    merged = []
+
+    sorted_ranges.each do |begin_ms, end_ms|
+      if merged.empty?
+        merged << [begin_ms, end_ms]
+        next
+      end
+
+      last_begin_ms, last_end_ms = merged[-1]
+      if last_end_ms.nil? || begin_ms <= last_end_ms
+        merged[-1] = [last_begin_ms, merge_section_end(last_end_ms, end_ms)]
+      else
+        merged << [begin_ms, end_ms]
+      end
+    end
+
+    merged
+  end
+
+  def self.merge_section_end left_end_ms, right_end_ms
+    return nil if left_end_ms.nil? || right_end_ms.nil?
+
+    [left_end_ms, right_end_ms].max
+  end
+
   def self.find_or_create_by_tag_name! name, category:
     tn = TagName.find_undiscard_or_create_by!(name: name.to_s.strip)
     tn = tn.canonical if tn.canonical_id?
@@ -228,4 +328,36 @@ class Tag < ApplicationRecord
       errors.add :category, 'ニジラーと紐づいてゐるタグはニジラー・カテゴリである必要があります．'
     end
   end
+
+  def self.time_to_ms! str, tag_name:
+    match =
+        case str
+        when /\A(?<seconds>\d+)(?:\.(?<ms>\d{1,3}))?\z/
+          { hours: nil, minutes: nil, seconds: Regexp.last_match[:seconds],
+            ms: Regexp.last_match[:ms] }
+        when /\A(?<minutes>\d+):(?<seconds>[0-5]?\d)(?:\.(?<ms>\d{1,3}))?\z/
+          { hours: nil, minutes: Regexp.last_match[:minutes],
+            seconds: Regexp.last_match[:seconds],
+            ms: Regexp.last_match[:ms] }
+        when /\A(?<hours>\d+):(?<minutes>[0-5]?\d):(?<seconds>[0-5]?\d)(?:\.(?<ms>\d{1,3}))?\z/
+          { hours: Regexp.last_match[:hours],
+            minutes: Regexp.last_match[:minutes],
+            seconds: Regexp.last_match[:seconds],
+            ms: Regexp.last_match[:ms] }
+        end
+
+    raise SectionLiteralParseError.new(tag_name, str) unless match
+
+    total_s = match[:seconds].to_i
+    total_s += match[:minutes].to_i * 60 if match[:minutes]
+    total_s += match[:hours].to_i * 3_600 if match[:hours]
+
+    total_s * 1_000 + match[:ms].to_s.ljust(3, '0')[0, 3].to_i
+  end
+
+  def nico_tags_cannot_be_deprecated
+    if nico? && deprecated_at.present?
+      errors.add :deprecated_at, 'ニコタグは廃止できません．'
+    end
+  end
 end

backend/app/models/tag_implication.rb

@@ -6,6 +6,7 @@ class TagImplication < ApplicationRecord
   validates :parent_tag_id, presence: true
 
   validate :parent_tag_mustnt_be_itself
+  validate :parent_tag_mustnt_create_cycle
 
   private
 
@@ -14,4 +15,27 @@ class TagImplication < ApplicationRecord
       errors.add :parent_tag_id, '親タグは子タグと同一であってはなりません．'
     end
   end
+
+  def parent_tag_mustnt_create_cycle
+    return if tag_id.blank? || parent_tag_id.blank?
+    return if errors[:parent_tag_id].present?
+
+    seen = { }
+    stack = [parent_tag_id]
+
+    until stack.empty?
+      current_id = stack.pop
+      next if seen[current_id]
+
+      seen[current_id] = true
+
+      if current_id == tag_id
+        errors.add :parent_tag_id, '親タグに子孫タグを指定すると循環します．'
+        errors.add :base, 'タグの親子関係が循環します．'
+        return
+      end
+
+      stack.concat(TagImplication.where(tag_id: current_id).pluck(:parent_tag_id))
+    end
+  end
 end

backend/app/models/user.rb

@@ -7,7 +7,8 @@ class User < ApplicationRecord
 
   has_many :created_posts,
            class_name: 'Post', foreign_key: :uploaded_user_id, dependent: :nullify
-  has_many :settings
+  has_one :setting, dependent: :destroy
+  has_many :theme_slots, class_name: 'UserThemeSlot', dependent: :destroy
   has_many :user_ips, dependent: :destroy
   has_many :ip_addresses, through: :user_ips
   has_many :user_post_views, dependent: :destroy

backend/app/models/user_theme_slot.rb

@@ -0,0 +1,27 @@
+class UserThemeSlot < ApplicationRecord
+  BASE_THEMES = ['light', 'dark'].freeze
+  SLOT_NOS = [1, 2, 3].freeze
+
+  belongs_to :user
+
+  validates :user_id, presence: true
+  validates :base_theme, presence: true, inclusion: { in: BASE_THEMES }
+  validates :slot_no, presence: true, inclusion: { in: SLOT_NOS }
+  validates :tokens, presence: true
+  validates :user_id, uniqueness: { scope: [:base_theme, :slot_no] }
+
+  validate :tokens_must_be_object
+
+  def serializable_hash(options = nil)
+    hash = { only: [:base_theme, :slot_no, :tokens, :created_at, :updated_at] }
+    super(hash.merge(options || {}))
+  end
+
+  private
+
+  def tokens_must_be_object
+    return if tokens.is_a?(Hash)
+
+    errors.add(:tokens, 'は JSON object で指定してください．')
+  end
+end

backend/app/models/version_record.rb

@@ -1,15 +1,23 @@
 module VersionRecord
   extend ActiveSupport::Concern
 
+  DEFAULT_EVENT_TYPE_MAP = { create: 'create',
+                             update: 'update',
+                             discard: 'discard',
+                             restore: 'restore' }.freeze
+
   def readonly? = persisted?
 
   included do
+    event_type_map = if const_defined?(:EVENT_TYPE_MAP, false)
+                       const_get(:EVENT_TYPE_MAP)
+                     else
+                       DEFAULT_EVENT_TYPE_MAP
+                     end
+
     belongs_to :created_by_user, class_name: 'User', optional: true
 
-    enum :event_type, { create: 'create',
-                        update: 'update',
-                        discard: 'discard',
-                        restore: 'restore' }, prefix: true, validate: true
+    enum :event_type, event_type_map, prefix: true, validate: true
 
     validates :version_no, presence: true, numericality: { only_integer: true, greater_than: 0 }
     validates :event_type, presence: true

backend/app/models/wiki_page.rb

@@ -22,6 +22,7 @@ class WikiPage < ApplicationRecord
   validates :body, presence: true
 
   def title = tag_name.name
+  def deprecated_at = tag_name.tag&.deprecated_at
 
   def title= val
     (self.tag_name ||= build_tag_name).name = val

backend/app/representations/material_repr.rb

@@ -2,7 +2,9 @@
 
 
 module MaterialRepr
-  BASE = { only: [:id, :url, :created_at, :updated_at],
+  BASE = { only: [:id, :url, :version_no, :source_kind, :source_uri,
+                  :source_path, :source_file_id, :normalized_source_key,
+                  :created_at, :updated_at],
            methods: [:content_type],
            include: { tag: TagRepr::BASE,
                       created_by_user: UserRepr::BASE,
@@ -15,10 +17,93 @@ module MaterialRepr
         file: if material.file.attached?
                 Rails.application.routes.url_helpers.rails_storage_proxy_url(
                     material.file, host:)
-              end)
+              end,
+        thumbnail: thumbnail_url(material, host:),
+        thumbnail_fallback_text: thumbnail_fallback_text(material),
+        thumbnail_fallback_kind: thumbnail_fallback_kind(material),
+        media_kind: media_kind(material),
+        file_byte_size: material.file_byte_size,
+        export_paths: export_paths(material),
+        export_items: export_items(material))
   end
 
   def many materials, host:
     materials.map { |m| base(m, host:) }
   end
+
+  def list material, host:
+    { id: material.id,
+      version_no: material.version_no,
+      url: material.url,
+      source_kind: material.source_kind,
+      source_uri: material.source_uri,
+      source_path: material.source_path,
+      source_file_id: material.source_file_id,
+      normalized_source_key: material.normalized_source_key,
+      tag: compact_tag(material.tag),
+      thumbnail: thumbnail_url(material, host:),
+      thumbnail_fallback_text: thumbnail_fallback_text(material),
+      thumbnail_fallback_kind: thumbnail_fallback_kind(material),
+      media_kind: media_kind(material),
+      content_type: material.content_type,
+      file_byte_size: material.file_byte_size,
+      created_at: material.created_at,
+      updated_at: material.updated_at,
+      export_paths: export_paths(material),
+      export_items: export_items(material) }
+  end
+
+  def list_many materials, host:
+    materials.map { |m| list(m, host:) }
+  end
+
+  def export_paths material
+    material.material_export_items.each_with_object({ }) do |item, hash|
+      hash[item.profile] = item.enabled ? item.export_path : ''
+    end
+  end
+
+  def export_items material
+    material.material_export_items.map do |item|
+      { id: item.id,
+        profile: item.profile,
+        export_path: item.export_path,
+        enabled: item.enabled }
+    end
+  end
+
+  def thumbnail_url material, host:
+    return nil unless material.thumbnail.attached?
+
+    Rails.application.routes.url_helpers.rails_storage_proxy_url(
+        material.thumbnail, host:)
+  end
+
+  def thumbnail_fallback_text material
+    material.tag&.name || material.created_at&.strftime('%Y-%m-%d')
+  end
+
+  def thumbnail_fallback_kind material
+    material.tag.present? ? 'tag_name' : 'created_at'
+  end
+
+  def media_kind material
+    return 'url_only' unless material.file.attached?
+
+    content_type = material.file.blob.content_type.to_s
+    return 'image' if content_type.start_with?('image/')
+    return 'video' if content_type.start_with?('video/')
+    return 'audio' if content_type.start_with?('audio/')
+
+    'file_other'
+  end
+
+  def compact_tag tag
+    return nil unless tag
+
+    { id: tag.id,
+      name: tag.name,
+      category: tag.category,
+      deprecated_at: tag.deprecated_at }
+  end
 end

backend/app/representations/post_repr.rb

@@ -8,6 +8,7 @@ module PostRepr
       :url,
       :title,
       :thumbnail_base,
+      :video_ms,
       :original_created_from,
       :original_created_before,
       :created_at,
@@ -18,7 +19,7 @@ module PostRepr
 
   def base post, current_user = nil
     json = common(post)
-    json['tags'] = tag_json(post.tags)
+    json['tags'] = tag_json(post)
     json['uploaded_user'] = post.uploaded_user && UserRepr.base(post.uploaded_user)
     json['viewed'] = current_user ? current_user.viewed?(post) : false
     json
@@ -52,8 +53,16 @@ module PostRepr
                .merge('thumbnail' => thumbnail_url(post))
   end
 
-  def tag_json tags
-    tags.map { |tag| TagRepr.inline(tag) }
+  def tag_json post
+    post
+        .active_post_tags
+        .reject { _1.tag.deprecated? }
+        .sort_by { _1.tag.name }
+        .map { |post_tag|
+      TagRepr.inline(post_tag.tag).merge(
+          'children' => [],
+          'sections' => post_tag.sections.as_json(only: [:begin_ms, :end_ms]))
+    }
   end
 
   def thumbnail_url post

backend/app/representations/tag_repr.rb

@@ -2,7 +2,7 @@
 
 
 module TagRepr
-  BASE = { only: [:id, :category, :post_count, :created_at, :updated_at],
+  BASE = { only: [:id, :category, :post_count, :created_at, :updated_at, :deprecated_at],
            methods: [:name, :has_wiki, :material_id, :has_deerjikists] }.freeze
 
   module_function

backend/app/representations/wiki_page_repr.rb

@@ -2,7 +2,7 @@
 
 
 module WikiPageRepr
-  BASE = { methods: [:title] }.freeze
+  BASE = { methods: [:title, :deprecated_at] }.freeze
 
   module_function
 

backend/app/services/google_drive/api_client.rb

@@ -0,0 +1,233 @@
+require 'json'
+require 'jwt'
+require 'net/http'
+require 'openssl'
+require 'tempfile'
+require 'uri'
+
+
+module GoogleDrive
+  class ApiClient
+    DRIVE_ENDPOINT = 'https://www.googleapis.com/drive/v3'
+    TOKEN_ENDPOINT = 'https://oauth2.googleapis.com/token'
+    FOLDER_MIME_TYPE = 'application/vnd.google-apps.folder'
+    NATIVE_FILE_MIME_TYPE_PREFIX = 'application/vnd.google-apps.'
+    DRIVE_SCOPE = 'https://www.googleapis.com/auth/drive.readonly'
+
+    def initialize service_account_email: ENV['GOOGLE_DRIVE_SERVICE_ACCOUNT_EMAIL'],
+                   private_key: ENV['GOOGLE_DRIVE_PRIVATE_KEY'],
+                   private_key_path: ENV['GOOGLE_DRIVE_PRIVATE_KEY_PATH'],
+                   subject: ENV['GOOGLE_DRIVE_SUBJECT']
+      @service_account_email = service_account_email.to_s
+      @private_key = load_private_key(private_key, private_key_path)
+      @subject = subject.to_s.presence
+      @access_token = nil
+    end
+
+    def list_material_files_under_folder folder_id
+      files = []
+      each_material_file_under_folder(folder_id) { |entry| files << entry }
+      files
+    end
+
+    def each_material_file_under_folder folder_id
+      return enum_for(__method__, folder_id) unless block_given?
+
+      walk_folder(folder_id, nil) do |entry, relative_path|
+        next if entry['mimeType'] == FOLDER_MIME_TYPE
+        next if native_file?(entry['mimeType'])
+
+        yield build_file_entry(entry, relative_path)
+      end
+    end
+
+    def fetch_material_file file_id
+      metadata = get_file(file_id)
+      return nil if native_file?(metadata['mimeType'])
+
+      build_file_entry(metadata, metadata['name'])
+    end
+
+    def download_to_tempfile file_id, filename:
+      tempfile = Tempfile.new(['material-sync', File.extname(filename.to_s)])
+      tempfile.binmode
+      request_binary("/files/#{ file_id }",
+                     { alt: 'media', supportsAllDrives: true }) do |chunk|
+        tempfile.write(chunk.b)
+      end
+      tempfile.rewind
+      tempfile
+    rescue StandardError
+      tempfile&.close!
+      raise
+    end
+
+    def extract_file_id value
+      raw = value.to_s.strip
+      return nil if raw.blank?
+      return raw unless raw.include?('/')
+
+      uri = URI.parse(raw)
+      return uri.query.to_s[%r{(?:^|&)id=([^&]+)}, 1] if uri.query.present?
+      return uri.path[%r{/folders/([^/]+)}, 1] if uri.path.include?('/folders/')
+
+      uri.path[%r{/d/([^/]+)}, 1]
+    rescue URI::InvalidURIError
+      nil
+    end
+
+    private
+
+    def walk_folder folder_id, prefix, &block
+      list_children(folder_id).each do |entry|
+        relative_path = MaterialSyncExportPath.build(prefix:,
+                                                     relative_path: entry['name'])
+        if entry['mimeType'] == FOLDER_MIME_TYPE
+          walk_folder(entry['id'], relative_path, &block)
+          next
+        end
+
+        block.call(entry, relative_path)
+      end
+    end
+
+    def build_file_entry entry, relative_path
+      { id: entry['id'],
+        name: entry['name'],
+        mime_type: entry['mimeType'],
+        relative_path: MaterialSyncExportPath.normalize_path(relative_path),
+        sha256_checksum: entry['sha256Checksum'],
+        web_view_link: entry['webViewLink'],
+        web_content_link: entry['webContentLink'] }
+    end
+
+    def list_children folder_id
+      files = []
+      page_token = nil
+
+      loop do
+        response =
+            request_json('/files', {
+                q: "'#{ folder_id }' in parents and trashed = false",
+                fields: 'nextPageToken,files(id,name,mimeType,sha256Checksum,' \
+                        'webViewLink,webContentLink)',
+                orderBy: 'folder,name',
+                pageSize: 1000,
+                supportsAllDrives: true,
+                includeItemsFromAllDrives: true,
+                pageToken: page_token }.compact)
+        files.concat(response.fetch('files'))
+        page_token = response['nextPageToken']
+        break if page_token.blank?
+      end
+
+      files
+    end
+
+    def get_file file_id
+      request_json("/files/#{ file_id }",
+                   fields: 'id,name,mimeType,sha256Checksum,webViewLink,webContentLink',
+                   supportsAllDrives: true)
+    end
+
+    def request_json path, params = {}
+      response = request(:get, path, params:)
+      unless response.is_a?(Net::HTTPSuccess)
+        raise "Google Drive API error: #{ response.code } #{ response.body }"
+      end
+
+      JSON.parse(response.body)
+    end
+
+    def request_binary path, params = {}
+      request(:get, path, params:) do |response|
+        unless response.is_a?(Net::HTTPSuccess)
+          raise "Google Drive download error: #{ response.code } #{ response.body }"
+        end
+
+        response.read_body do |chunk|
+          yield chunk.b
+        end
+      end
+    end
+
+    def request method, path, params: nil
+      uri = URI(DRIVE_ENDPOINT + path)
+      uri.query = URI.encode_www_form(params) if params.present?
+
+      klass =
+          case method
+          when :get
+            Net::HTTP::Get
+          else
+            raise ArgumentError, "Unsupported Google Drive request method: #{ method }"
+          end
+      request = klass.new(uri)
+      request['Authorization'] = "Bearer #{ access_token }"
+
+      Net::HTTP.start(uri.host,
+                      uri.port,
+                      use_ssl: true,
+                      open_timeout: 10,
+                      read_timeout: 60) do |http|
+        if block_given?
+          http.request(request) do |response|
+            return yield response
+          end
+        else
+          http.request(request)
+        end
+      end
+    end
+
+    def access_token
+      @access_token ||= fetch_access_token
+    end
+
+    def fetch_access_token
+      raise 'GOOGLE_DRIVE_SERVICE_ACCOUNT_EMAIL is required' if @service_account_email.blank?
+      raise 'Google Drive private key is required' if @private_key.blank?
+
+      payload = { iss: @service_account_email,
+                  scope: DRIVE_SCOPE,
+                  aud: TOKEN_ENDPOINT,
+                  exp: 1.hour.from_now.to_i,
+                  iat: Time.current.to_i }
+      payload[:sub] = @subject if @subject.present?
+
+      assertion = JWT.encode(payload, @private_key, 'RS256')
+      uri = URI(TOKEN_ENDPOINT)
+      request = Net::HTTP::Post.new(uri)
+      request.set_form_data(
+          grant_type: 'urn:ietf:params:oauth:grant-type:jwt-bearer',
+          assertion:)
+
+      response =
+          Net::HTTP.start(uri.host,
+                          uri.port,
+                          use_ssl: true,
+                          open_timeout: 10,
+                          read_timeout: 30) do |http|
+            http.request(request)
+          end
+      unless response.is_a?(Net::HTTPSuccess)
+        raise "Google OAuth error: #{ response.code } #{ response.body }"
+      end
+
+      JSON.parse(response.body).fetch('access_token')
+    end
+
+    def load_private_key private_key, private_key_path
+      raw = private_key.to_s
+      raw = raw.gsub('\n', "\n") if raw.present?
+      raw = File.read(private_key_path) if raw.blank? && private_key_path.present?
+      return nil if raw.blank?
+
+      OpenSSL::PKey::RSA.new(raw)
+    end
+
+    def native_file? mime_type
+      mime_type.to_s.start_with?(NATIVE_FILE_MIME_TYPE_PREFIX)
+    end
+  end
+end

backend/app/services/material_file_sha256.rb

@@ -0,0 +1,57 @@
+require 'digest'
+require 'json'
+
+class MaterialFileSha256
+  def self.blob_metadata blob
+    metadata = blob.metadata
+    return metadata if metadata.is_a?(Hash)
+    return { } if metadata.blank?
+
+    JSON.parse(metadata)
+  rescue JSON::ParserError
+    { }
+  end
+
+  def self.metadata_sha256 blob
+    blob_metadata(blob)['sha256'].presence
+  end
+
+  def self.assign_metadata_sha256! blob, sha256
+    return if sha256.blank?
+
+    metadata = blob_metadata(blob)
+    metadata['sha256'] = sha256
+    blob.metadata = metadata
+    blob.save! if blob.changed?
+  end
+
+  def self.from_blob blob, allow_download: false
+    sha256 = metadata_sha256(blob)
+    return sha256 if sha256.present?
+    return nil unless allow_download
+
+    begin
+      blob.open do |file|
+        sha256 = Digest::SHA256.file(file.path).hexdigest
+        assign_metadata_sha256!(blob, sha256)
+        sha256
+      end
+    rescue ActiveStorage::FileNotFoundError, ArgumentError => error
+      Rails.logger.warn(
+          "MaterialFileSha256.from_blob failed for blob_id=#{blob.id}: " \
+          "#{error.class}: #{error.message}",
+      )
+      nil
+    end
+  end
+
+  def self.from_upload upload
+    tempfile = upload&.tempfile
+    return nil unless tempfile
+
+    tempfile.rewind
+    Digest::SHA256.file(tempfile.path).hexdigest.tap do
+      tempfile.rewind
+    end
+  end
+end

backend/app/services/material_import_block_matcher.rb

@@ -0,0 +1,7 @@
+class MaterialImportBlockMatcher
+  def self.match_for_sha256 sha256
+    return nil if sha256.blank?
+
+    MaterialImportBlock.find_by(match_kind: 'sha256', sha256:)
+  end
+end

backend/app/services/material_sync_export_path.rb

@@ -0,0 +1,56 @@
+class MaterialSyncExportPath
+  class << self
+    def build prefix: nil, relative_path: nil, filename: nil, source_file_id: nil
+      path = normalize_path(relative_path)
+      path = fallback_filename(filename, source_file_id) if path.blank?
+
+      normalized_prefix = normalize_path(prefix)
+      return path if normalized_prefix.blank?
+      return normalized_prefix if path.blank?
+
+      [normalized_prefix, path].join('/')
+    end
+
+    def normalize_path path
+      raw = path.to_s.delete("\0").tr('\\', '/').strip
+      raw = raw.sub(%r{\A[A-Za-z]:/+}, '')
+      raw = raw.sub(%r{\A/+}, '')
+      return nil if raw.blank?
+
+      segments = raw.split('/').filter_map do |segment|
+        normalized = normalize_segment(segment)
+        normalized.presence
+      end
+      return nil if segments.empty?
+
+      segments.join('/')
+    end
+
+    def uniquify path, source_file_id
+      normalized = normalize_path(path)
+      return normalized if normalized.blank? || source_file_id.blank?
+
+      ext = File.extname(normalized)
+      base = ext.present? ? normalized.delete_suffix(ext) : normalized
+      "#{ base }--#{ source_file_id }#{ ext }"
+    end
+
+    private
+
+    def fallback_filename filename, source_file_id
+      name = normalize_path(filename)
+      return name if name.present?
+      return nil if source_file_id.blank?
+
+      source_file_id.to_s
+    end
+
+    def normalize_segment segment
+      cleaned = segment.to_s.delete("\0").tr('\\/', '_').strip
+      return nil if cleaned.blank? || cleaned == '.'
+      return '__' if cleaned == '..'
+
+      cleaned
+    end
+  end
+end

backend/app/services/material_sync_importer.rb

@@ -0,0 +1,259 @@
+require 'digest'
+
+class MaterialSyncImporter
+  Result = Struct.new(:material, :action, :suppressed, :suppression, keyword_init: true)
+
+  def self.import! attributes
+    new(attributes).import!
+  end
+
+  def initialize attributes
+    @attributes = attributes
+  end
+
+  def import!
+    source = source_attributes
+    key = normalized_source_key(source)
+    raise ArgumentError, 'normalized_source_key is required for material sync' if key.blank?
+
+    suppression = suppression_for(source)
+    if suppression
+      return Result.new(material: nil,
+                        action: :suppressed,
+                        suppressed: true,
+                        suppression:)
+    end
+
+    material =
+        Material
+        .unscoped
+        .find_or_initialize_by(normalized_source_key: key)
+    if unchanged?(material, source)
+      return Result.new(material:,
+                        action: :unchanged,
+                        suppressed: false,
+                        suppression: nil)
+    end
+
+    event_type =
+        if material.new_record?
+          :create
+        elsif material.discarded?
+          :restore
+        else
+          :update
+        end
+    uploaded_blob = uploaded_blob!
+    if @import_block
+      return Result.new(material: nil,
+                        action: :suppressed,
+                        suppressed: true,
+                        suppression: @import_block)
+    end
+
+    Material.transaction do
+      if material.persisted?
+        MaterialVersionRecorder.ensure_snapshot!(material,
+                                                 created_by_user: @attributes[:updated_by_user])
+      end
+      material.assign_attributes(material_attributes_for(material).merge(source))
+      material.discarded_at = nil if material.respond_to?(:discarded_at=)
+      material.file.attach(uploaded_blob) if uploaded_blob
+      material.save!
+      upsert_export_item!(material)
+      MaterialVersionRecorder.record!(material:,
+                                      event_type:,
+                                      created_by_user: @attributes[:updated_by_user])
+    end
+    MaterialThumbnailGenerator.generate!(material)
+
+    Result.new(material:,
+               action: event_type == :create ? :imported : :updated,
+               suppressed: false,
+               suppression: nil)
+  rescue StandardError
+    uploaded_blob&.purge_later
+    raise
+  ensure
+    close_tempfile!
+  end
+
+  private
+
+  def source_attributes
+    { source_kind: @attributes[:source_kind],
+      source_uri: @attributes[:source_uri],
+      source_path: @attributes[:source_path],
+      source_file_id: @attributes[:source_file_id] }
+  end
+
+  def normalized_source_key source
+    MaterialSyncSuppression.normalize_source_key(source_kind: source[:source_kind],
+                                                 source_uri: source[:source_uri],
+                                                 source_path: source[:source_path],
+                                                 source_file_id: source[:source_file_id])
+  end
+
+  def material_attributes_for material
+    attrs =
+        @attributes
+        .except(:source_kind, :source_uri, :source_path, :source_file_id,
+                :file_blob, :file_tempfile, :file_downloader,
+                :filename, :content_type,
+                :file_sha256, :export_path, :profile, :tag, :url)
+
+    if material.new_record?
+      attrs[:tag] = @attributes[:tag] if @attributes.key?(:tag)
+      attrs[:url] = @attributes[:url] if @attributes.key?(:url)
+      return attrs
+    end
+
+    if @attributes.key?(:tag) && @attributes[:tag].present?
+      attrs[:tag] = @attributes[:tag]
+    end
+    if @attributes.key?(:url) && @attributes[:url].present?
+      attrs[:url] = @attributes[:url]
+    end
+
+    attrs
+  end
+
+  def suppression_for source
+    if source[:source_kind] == 'google_drive_file' && source[:source_path].present?
+      return MaterialSyncSuppressionMatcher.match_google_drive_candidate(
+          drive_file_id: source[:source_file_id],
+          relative_path: source[:source_path])
+    end
+
+    MaterialSyncSuppressionMatcher.match(**source)
+  end
+
+  def uploaded_blob!
+    return @attributes[:file_blob] if @attributes[:file_blob]
+
+    tempfile = upload_tempfile
+    return nil unless tempfile
+
+    tempfile.rewind
+    file_sha256 = @attributes[:file_sha256] || Digest::SHA256.file(tempfile.path).hexdigest
+    @attributes[:file_sha256] = file_sha256
+
+    @import_block = MaterialImportBlockMatcher.match_for_sha256(file_sha256)
+    if @import_block
+      tempfile.rewind
+      return nil
+    end
+
+    blob = ActiveStorage::Blob.create_and_upload!(
+        io: tempfile,
+        filename: @attributes[:filename],
+        content_type: @attributes[:content_type])
+    MaterialFileSha256.assign_metadata_sha256!(blob, file_sha256)
+    tempfile.rewind
+    blob
+  end
+
+  def upload_tempfile
+    return @upload_tempfile if defined?(@upload_tempfile)
+
+    @upload_tempfile = @attributes[:file_tempfile]
+    if @upload_tempfile.blank? && @attributes[:file_downloader]
+      @upload_tempfile = @attributes[:file_downloader].call
+    end
+    @upload_tempfile
+  end
+
+  def upsert_export_item! material
+    export_path = resolved_export_path(material)
+    return if export_path.blank?
+
+    item = material.material_export_items.find_or_initialize_by(profile: effective_profile)
+    item.export_path = export_path
+    item.enabled = true
+    item.created_by_user ||= @attributes[:created_by_user]
+    item.save!
+  end
+
+  def export_path_taken_by_other? material, profile, export_path
+    MaterialExportItem
+      .where(profile:, export_path:)
+      .where.not(material_id: material.id)
+      .exists?
+  end
+
+  def close_tempfile!
+    tempfile = upload_tempfile
+    return unless tempfile
+
+    tempfile.close! unless tempfile.closed?
+  rescue StandardError
+    nil
+  end
+
+  def unchanged? material, source
+    return false if material.new_record? || material.discarded?
+    return false unless same_source_attributes?(material, source)
+    return false unless same_export_path?(material)
+    return false unless same_material_attributes?(material)
+
+    same_file_snapshot?(material)
+  end
+
+  def same_source_attributes? material, source
+    material.source_kind == source[:source_kind] \
+      && material.source_uri == source[:source_uri] \
+      && material.source_path == source[:source_path] \
+      && material.source_file_id == source[:source_file_id]
+  end
+
+  def same_export_path? material
+    expected = resolved_export_path(material)
+    current = material.material_export_items.find { |item| item.profile == effective_profile }
+
+    return current.blank? if expected.blank?
+
+    current&.enabled && current.export_path == expected
+  end
+
+  def same_material_attributes? material
+    same_tag_attribute?(material) && same_url_attribute?(material)
+  end
+
+  def same_file_snapshot? material
+    expected_sha256 = @attributes[:file_sha256].to_s.presence
+
+    if expected_sha256.present?
+      return false unless material.file.attached?
+
+      return MaterialFileSha256.metadata_sha256(material.file.blob) == expected_sha256
+    end
+
+    !material.file.attached?
+  end
+
+  def effective_profile
+    @attributes[:profile].presence || 'legacy_drive'
+  end
+
+  def resolved_export_path material
+    export_path = @attributes[:export_path].to_s.strip
+    return export_path if export_path.blank?
+    return export_path unless export_path_taken_by_other?(material, effective_profile, export_path)
+
+    MaterialSyncExportPath.uniquify(export_path, @attributes[:source_file_id])
+  end
+
+  def same_tag_attribute? material
+    return true unless @attributes.key?(:tag)
+    return true if @attributes[:tag].blank?
+
+    material.tag_id == @attributes[:tag].id
+  end
+
+  def same_url_attribute? material
+    return true unless @attributes.key?(:url)
+    return true if @attributes[:url].blank?
+
+    material.url == @attributes[:url]
+  end
+end

backend/app/services/material_sync_runner.rb

@@ -0,0 +1,251 @@
+class MaterialSyncRunner
+  Result = Struct.new(:imported, :updated, :unchanged, :suppressed, :failed,
+                      :errors, keyword_init: true)
+
+  def self.sync_enabled!
+    results = MaterialSyncSource.enabled.order(:id).map { |source| new(source).sync! }
+
+    Result.new(imported: results.sum(&:imported),
+               updated: results.sum(&:updated),
+               unchanged: results.sum(&:unchanged),
+               suppressed: results.sum(&:suppressed),
+               failed: results.sum(&:failed),
+               errors: results.flat_map(&:errors))
+  end
+
+  def initialize source
+    @source = source
+  end
+
+  def sync!
+    result = Result.new(imported: 0, updated: 0, unchanged: 0,
+                        suppressed: 0, failed: 0, errors: [])
+
+    if @source.source_kind == 'google_drive_path'
+      sync_google_drive_path!(result)
+    else
+      candidates.each do |candidate|
+        next if candidate.blank?
+
+        sync_candidate!(candidate, result)
+      end
+    end
+
+    @source.update!(last_synced_at: Time.current)
+    log_result(result)
+    result
+  rescue NotImplementedError, StandardError => e
+    result.failed += 1
+    result.errors << { source_id: @source.id, error: e.message }
+    log_result(result)
+    result
+  end
+
+  private
+
+  def candidates
+    case @source.source_kind
+    when 'uri'
+      [uri_candidate]
+    when 'google_drive_file'
+      [google_drive_file_candidate]
+    when 'legacy_drive_path'
+      raise NotImplementedError, 'legacy_drive_path material sync is not implemented'
+    else
+      raise NotImplementedError, "Unsupported material sync source_kind: #{ @source.source_kind }"
+    end
+  end
+
+  def uri_candidate
+    { source_kind: @source.source_kind,
+      source_uri: @source.source_uri,
+      source_path: @source.source_path,
+      source_file_id: @source.source_file_id,
+      url: @source.source_uri,
+      tag: nil,
+      created_by_user: @source.created_by_user,
+      updated_by_user: @source.updated_by_user || @source.created_by_user }
+  end
+
+  def sync_candidate! candidate, result
+    block = MaterialImportBlockMatcher.match_for_sha256(candidate[:file_sha256])
+    if block
+      result.suppressed += 1
+      Rails.logger.info(
+          material_sync_log(action: 'suppressed',
+                            reason: block.reason,
+                            normalized_source_key: candidate_normalized_source_key(candidate)))
+      return
+    end
+
+    suppression = suppression_for(candidate)
+
+    if suppression
+      result.suppressed += 1
+      Rails.logger.info(
+          material_sync_log(action: 'suppressed',
+                            normalized_source_key: suppression.normalized_source_key))
+      return
+    end
+
+    import = MaterialSyncImporter.import!(candidate)
+    result.public_send("#{ import.action }=", result.public_send(import.action) + 1)
+  rescue StandardError => e
+    result.failed += 1
+    result.errors << { source_id: @source.id,
+                       normalized_source_key: candidate_normalized_source_key(candidate),
+                       error: e.message }
+    Rails.logger.warn(
+        material_sync_log(action: 'failed',
+                          error: e.message,
+                          normalized_source_key: candidate_normalized_source_key(candidate)))
+  ensure
+    close_candidate_tempfile(candidate)
+  end
+
+  def google_drive_path_candidates
+    folder_id = google_drive_folder_id
+    Enumerator.new do |entries|
+      drive_client.each_material_file_under_folder(folder_id).each do |entry|
+        entries << build_google_drive_candidate(entry)
+      end
+    end
+  end
+
+  def sync_google_drive_path! result
+    folder_id = google_drive_folder_id
+    scanned_count = 0
+
+    drive_client.each_material_file_under_folder(folder_id) do |entry|
+      scanned_count += 1
+      sync_candidate!(build_google_drive_candidate(entry), result)
+      log_google_drive_progress(folder_id, scanned_count, result) if progress_log_scan_count?(scanned_count)
+    end
+
+    log_google_drive_progress(folder_id, scanned_count, result, summary: true)
+  end
+
+  def google_drive_file_candidate
+    entry = drive_client.fetch_material_file(google_drive_file_id)
+    return nil unless entry
+
+    build_google_drive_candidate(entry, single_file: true)
+  end
+
+  def build_google_drive_candidate entry, single_file: false
+    relative_path =
+        if single_file
+          nil
+        else
+          entry[:relative_path]
+        end
+    export_path =
+        MaterialSyncExportPath.build(prefix: @source.export_path_prefix,
+                                     relative_path:,
+                                     filename: entry[:name],
+                                     source_file_id: entry[:id])
+
+    { source_kind: 'google_drive_file',
+      source_uri: entry[:web_view_link] || google_drive_file_url(entry[:id]),
+      source_path: relative_path.presence || MaterialSyncExportPath.normalize_path(entry[:name]),
+      source_file_id: entry[:id],
+      filename: entry[:name],
+      content_type: entry[:mime_type],
+      file_downloader: lambda {
+        drive_client.download_to_tempfile(entry[:id], filename: entry[:name])
+      },
+      file_sha256: entry[:sha256_checksum],
+      export_path:,
+      profile: @source.profile,
+      tag: nil,
+      url: nil,
+      created_by_user: @source.created_by_user,
+      updated_by_user: @source.updated_by_user || @source.created_by_user }
+  end
+
+  def candidate_normalized_source_key candidate
+    MaterialSyncSuppression.normalize_source_key(source_kind: candidate[:source_kind],
+                                                 source_uri: candidate[:source_uri],
+                                                 source_path: candidate[:source_path],
+                                                 source_file_id: candidate[:source_file_id])
+  end
+
+  def suppression_for candidate
+    if candidate[:source_kind] == 'google_drive_file' && candidate[:source_path].present?
+      return MaterialSyncSuppressionMatcher.match_google_drive_candidate(
+          drive_file_id: candidate[:source_file_id],
+          relative_path: candidate[:source_path])
+    end
+
+    MaterialSyncSuppressionMatcher.match(source_kind: candidate[:source_kind],
+                                         source_uri: candidate[:source_uri],
+                                         source_path: candidate[:source_path],
+                                         source_file_id: candidate[:source_file_id])
+  end
+
+  def drive_client
+    @drive_client ||= GoogleDrive::ApiClient.new
+  end
+
+  def google_drive_folder_id
+    google_drive_target_id.tap do |id|
+      if id.blank?
+        raise ArgumentError, 'google_drive_path source_file_id or source_uri is required'
+      end
+    end
+  end
+
+  def google_drive_file_id
+    google_drive_target_id.tap do |id|
+      if id.blank?
+        raise ArgumentError, 'google_drive_file source_file_id or source_uri is required'
+      end
+    end
+  end
+
+  def google_drive_target_id
+    @source.source_file_id.presence || drive_client.extract_file_id(@source.source_uri)
+  end
+
+  def google_drive_file_url file_id
+    "https://drive.google.com/file/d/#{ file_id }/view"
+  end
+
+  def close_candidate_tempfile candidate
+    tempfile = candidate[:file_tempfile]
+    return unless tempfile
+
+    tempfile.close! unless tempfile.closed?
+  rescue StandardError
+    nil
+  end
+
+  def log_result result
+    Rails.logger.info(material_sync_log(imported: result.imported,
+                                        updated: result.updated,
+                                        unchanged: result.unchanged,
+                                        suppressed: result.suppressed,
+                                        failed: result.failed))
+  end
+
+  def progress_log_scan_count? scanned_count
+    scanned_count == 1 || (scanned_count % 50).zero?
+  end
+
+  def log_google_drive_progress folder_id, scanned_count, result, summary: false
+    Rails.logger.info(
+        material_sync_log(folder_id:,
+                          scanned_count:,
+                          imported: result.imported,
+                          updated: result.updated,
+                          unchanged: result.unchanged,
+                          suppressed: result.suppressed,
+                          failed: result.failed,
+                          progress: summary ? 'summary' : 'scan'))
+  end
+
+  def material_sync_log fields
+    { material_sync_source_id: @source.id,
+      material_sync_source_name: @source.name }.merge(fields).to_json
+  end
+end

backend/app/services/material_sync_suppression_matcher.rb

@@ -0,0 +1,68 @@
+class MaterialSyncSuppressionMatcher
+  def self.match source_kind:,
+                 source_uri: nil,
+                 drive_path: nil,
+                 drive_file_id: nil,
+                 source_path: nil,
+                 source_file_id: nil
+    key = MaterialSyncSuppression.normalize_source_key(source_kind:,
+                                                       source_uri:,
+                                                       drive_path:,
+                                                       drive_file_id:,
+                                                       source_path:,
+                                                       source_file_id:)
+    return nil if key.blank?
+
+    MaterialSyncSuppression.find_by(normalized_source_key: key)
+  end
+
+  def self.match_google_drive_candidate drive_file_id:, relative_path:
+    normalized_path = validate_relative_path!(relative_path)
+
+    exact = [
+      normalize_key('google_drive_file', drive_file_id),
+      normalize_key('google_drive_path', normalized_path),
+      normalize_key('legacy_drive_path', normalized_path),
+    ].compact
+
+    suppression =
+        MaterialSyncSuppression.find_by(normalized_source_key: exact)
+    return suppression if suppression
+
+    MaterialSyncSuppression
+      .where(source_kind: ['google_drive_path_prefix', 'legacy_drive_path_prefix'])
+      .where('drive_path = :path OR :path LIKE CONCAT(drive_path, "/%")', path: normalized_path)
+      .order(:id)
+      .first
+  end
+
+  def self.suppressed?(...)
+    match(...).present?
+  end
+
+  def self.validate_relative_path! relative_path
+    raw = relative_path.to_s.delete("\0").tr('\\', '/').strip
+    raise ArgumentError, 'relative_path is required' if raw.blank?
+    raise ArgumentError, 'relative_path must be relative' if raw.start_with?('/')
+    raise ArgumentError, 'relative_path must be relative' if raw.match?(/\A[A-Za-z]:\//)
+    if raw.start_with?('My Drive/', 'マイドライブ/')
+      raise ArgumentError, 'relative_path must be relative to source folder'
+    end
+    raise ArgumentError, 'relative_path must not contain //' if raw.include?('//')
+    raise ArgumentError, 'relative_path must not end with /' if raw.end_with?('/')
+
+    parts = raw.split('/')
+    if parts.any? { |part| part.in?(['.', '..']) }
+      raise ArgumentError, 'relative_path must not contain dot segments'
+    end
+
+    raw
+  end
+
+  def self.normalize_key source_kind, value
+    return nil if value.blank?
+
+    MaterialSyncSuppression.normalize_source_key(source_kind:, source_path: value,
+                                                 source_file_id: value)
+  end
+end

backend/app/services/material_sync_suppression_registrar.rb

@@ -0,0 +1,51 @@
+class MaterialSyncSuppressionRegistrar
+  def self.create! attributes, created_by_user:
+    new(attributes, created_by_user:).create!
+  end
+
+  def initialize attributes, created_by_user:
+    @attributes = attributes
+    @created_by_user = created_by_user
+  end
+
+  def create!
+    suppression = nil
+
+    MaterialSyncSuppression.transaction do
+      suppression = MaterialSyncSuppression.create!(
+          @attributes.merge(created_by_user: @created_by_user))
+      discard_existing_materials!(suppression)
+    end
+
+    suppression
+  end
+
+  private
+
+  def discard_existing_materials! suppression
+    matching_materials(suppression).find_each do |material|
+      MaterialVersionRecorder.ensure_snapshot!(material, created_by_user: @created_by_user)
+      material.discard!
+      MaterialVersionRecorder.record!(material:,
+                                      event_type: :discard,
+                                      created_by_user: @created_by_user)
+    end
+  end
+
+  def matching_materials suppression
+    materials = Material.unscoped.kept
+
+    case suppression.source_kind
+    when 'google_drive_path', 'legacy_drive_path'
+      materials.where(source_path: suppression.drive_path)
+    when 'google_drive_path_prefix', 'legacy_drive_path_prefix'
+      path = suppression.drive_path.to_s
+      materials.where(
+          'source_path = :path OR source_path LIKE :prefix',
+          path:,
+          prefix: "#{ path }/%")
+    else
+      materials.where(normalized_source_key: suppression.normalized_source_key)
+    end
+  end
+end

backend/app/services/material_thumbnail_generator.rb

@@ -0,0 +1,126 @@
+# frozen_string_literal: true
+
+require 'mini_magick'
+require 'open3'
+require 'tempfile'
+
+
+class MaterialThumbnailGenerator
+  SIZE = '180x180'
+
+  class << self
+    def generate! material
+      new(material).generate!
+    end
+  end
+
+  def initialize material
+    @material = material
+    @ffmpeg_stderr = []
+  end
+
+  def generate!
+    return log_result(:no_file) unless @material.file.attached?
+    return log_result(:unsupported_content_type) unless image? || video?
+
+    @material.file.blob.open do |file|
+      thumbnail = image? ? image_thumbnail(file.path) : video_thumbnail(file.path)
+      return log_result(:generation_failed) unless thumbnail
+
+      return attach_thumbnail(thumbnail)
+    end
+  rescue ActiveStorage::FileNotFoundError => e
+    log_result(:file_not_found, error: e)
+  rescue MiniMagick::Error => e
+    log_result(:mini_magick_error, error: e)
+  rescue ArgumentError, StandardError => e
+    log_result(:generation_failed, error: e)
+  end
+
+  private
+
+  def image? = content_type.start_with?('image/')
+
+  def video? = content_type.start_with?('video/')
+
+  def content_type
+    return nil unless @material.file.attached?
+
+    @material.file.blob.content_type.to_s
+  end
+
+  def image_thumbnail path
+    image = MiniMagick::Image.open(path)
+    image.resize(SIZE)
+    image.format('jpg')
+    image
+  end
+
+  def video_thumbnail path
+    [1, 0].each do |seconds|
+      tempfile = Tempfile.new(['material-thumbnail', '.jpg'])
+      tempfile.close
+      ok = extract_video_frame(path, tempfile.path, seconds)
+      next unless ok && File.size?(tempfile.path)
+
+      return image_thumbnail(tempfile.path)
+    ensure
+      tempfile&.unlink
+    end
+
+    nil
+  end
+
+  def extract_video_frame input_path, output_path, seconds
+    _stdout, stderr, status =
+        Open3.capture3('ffmpeg',
+                       '-y',
+                       '-ss', seconds.to_s,
+                       '-i', input_path,
+                       '-frames:v', '1',
+                       '-f', 'image2',
+                       output_path)
+    @ffmpeg_stderr << stderr if stderr.present?
+    status.success?
+  rescue Errno::ENOENT => e
+    @ffmpeg_stderr << "ffmpeg unavailable: #{ e.message }"
+    false
+  end
+
+  def attach_thumbnail image
+    blob = nil
+    File.open(image.path) do |io|
+      blob = ActiveStorage::Blob.create_and_upload!(
+          io:,
+          filename: 'material-thumbnail.jpg',
+          content_type: 'image/jpeg')
+    end
+    @material.thumbnail.attach(blob)
+    log_result(:attached)
+  rescue StandardError => e
+    blob&.purge_later
+    log_result(:attach_failed, error: e)
+  end
+
+  def log_result result, error: nil
+    log_payload = { material_id: @material.id,
+                    file_blob_id: file_blob_id,
+                    content_type:,
+                    result:,
+                    error_class: error&.class&.name,
+                    error_message: error&.message,
+                    ffmpeg_stderr: @ffmpeg_stderr.join("\n").presence }
+    if [:attached, :no_file, :unsupported_content_type].include?(result)
+      Rails.logger.info("Material thumbnail generation: #{ log_payload.to_json }")
+    else
+      Rails.logger.warn("Material thumbnail generation: #{ log_payload.to_json }")
+    end
+    result
+  end
+
+  def file_blob_id
+    return nil unless @material.file.attached?
+
+    @material.file.blob.id
+  end
+end

backend/app/services/material_version_recorder.rb

@@ -0,0 +1,73 @@
+class MaterialVersionRecorder < VersionRecorder
+  EVENT_TYPES = ['create', 'update', 'discard', 'restore'].freeze
+
+  def self.record! material:, event_type:, created_by_user:, file_snapshot: nil
+    new(material:, event_type:, created_by_user:, file_snapshot:).record!
+  end
+
+  def initialize material:, event_type:, created_by_user:, file_snapshot: nil
+    @file_snapshot = file_snapshot
+
+    super(record: material, event_type:, created_by_user:)
+  end
+
+  def self.ensure_snapshot! material, created_by_user:
+    return if material.material_versions.exists?
+
+    record!(material:, event_type: :create,
+            created_by_user: material.created_by_user || created_by_user)
+  end
+
+  private
+
+  def version_class = MaterialVersion
+  def version_association = :material_versions
+  def record_key = :material
+
+  def snapshot_attributes
+    blob = @record.file.attached? ? @record.file.blob : nil
+    file_snapshot = build_file_snapshot(blob)
+
+    { url: @record.url,
+      parent: @record.parent,
+      tag: @record.tag,
+      tag_name: @record.tag&.name,
+      tag_category: @record.tag&.category,
+      source_kind: @record.source_kind,
+      source_uri: @record.source_uri,
+      source_path: @record.source_path,
+      source_file_id: @record.source_file_id,
+      normalized_source_key: @record.normalized_source_key,
+      export_paths_json: @record.snapshot_export_paths,
+      discarded_at: @record.discarded_at,
+      file_blob_id: file_snapshot[:file_blob_id],
+      file_filename: file_snapshot[:file_filename],
+      file_content_type: file_snapshot[:file_content_type],
+      file_byte_size: file_snapshot[:file_byte_size],
+      file_checksum: file_snapshot[:file_checksum],
+      file_sha256: file_snapshot[:file_sha256] }
+  end
+
+  def build_file_snapshot blob
+    return @file_snapshot if @file_snapshot
+    return empty_file_snapshot unless blob
+
+    { file_blob_id: blob.id,
+      file_filename: blob.filename.to_s,
+      file_content_type: blob.content_type,
+      file_byte_size: blob.byte_size,
+      file_checksum: blob.checksum,
+      file_sha256: MaterialFileSha256.metadata_sha256(blob) }
+  end
+
+  def empty_file_snapshot
+    { file_blob_id: nil,
+      file_filename: nil,
+      file_content_type: nil,
+      file_byte_size: nil,
+      file_checksum: nil,
+      file_sha256: nil }
+  end
+
+  def event_types = self.class::EVENT_TYPES
+end

backend/app/services/material_zip_exporter.rb

@@ -0,0 +1,148 @@
+require 'stringio'
+require 'zlib'
+
+# Initial implementation keeps every file payload and the final ZIP in memory.
+# Keep this service boundary stable so job/cached export paths can replace it later.
+class MaterialZipExporter
+  Entry = Struct.new(:path, :data, :mtime, keyword_init: true)
+  MissingFile = Struct.new(:material_id, :export_path, :blob_id, :filename, keyword_init: true)
+
+  class EmptyExportError < StandardError; end
+  class DuplicatePathError < StandardError; end
+  class MissingFileError < StandardError
+    attr_reader :missing_files
+
+    def initialize missing_files
+      @missing_files = missing_files
+
+      super("Missing files: #{missing_files.map(&:export_path).join(', ')}")
+    end
+  end
+
+  def initialize profile: 'legacy_drive', tag_id: nil
+    @profile = profile.presence || 'legacy_drive'
+    @tag_id = tag_id.presence
+  end
+
+  def export
+    entries = build_entries
+    raise EmptyExportError if entries.empty?
+
+    ZipWriter.write(entries)
+  end
+
+  private
+
+  def build_entries
+    rows = MaterialExportItem
+           .enabled
+           .includes(material: { file_attachment: :blob })
+           .joins(:material)
+           .merge(Material.kept)
+           .where(profile: @profile)
+           .order(:export_path)
+
+    rows = rows.where(materials: { tag_id: @tag_id }) if @tag_id
+
+    missing_files = []
+
+    entries = rows.filter_map do |item|
+      material = item.material
+      next unless material.file.attached?
+
+      data = download_blob(item, missing_files)
+      next unless data
+
+      Entry.new(path: item.export_path,
+                data:,
+                mtime: material.updated_at || Time.current)
+    end
+
+    raise MissingFileError.new(missing_files) if missing_files.any?
+
+    paths = entries.map(&:path)
+    duplicated = paths.find { |path| paths.count(path) > 1 }
+    raise DuplicatePathError, duplicated if duplicated
+
+    entries
+  end
+
+  def download_blob item, missing_files
+    blob = item.material.file.blob
+
+    blob.download
+  rescue ActiveStorage::FileNotFoundError
+    missing_files << MissingFile.new(
+        material_id: item.material_id,
+        export_path: item.export_path,
+        blob_id: blob.id,
+        filename: blob.filename.to_s,
+    )
+    nil
+  end
+
+  class ZipWriter
+    VERSION_NEEDED = 20
+    GP_FLAG = 0x0800
+    COMPRESSION_STORE = 0
+
+    def self.write entries
+      new(entries).write
+    end
+
+    def initialize entries
+      @entries = entries
+      @central_directory = []
+    end
+
+    def write
+      io = StringIO.new(''.b)
+
+      @entries.each do |entry|
+        write_entry(io, entry)
+      end
+
+      central_start = io.pos
+      @central_directory.each { |header| io.write(header) }
+      central_size = io.pos - central_start
+
+      io.write([0x06054b50, 0, 0, @entries.size, @entries.size,
+                central_size, central_start, 0].pack('VvvvvVVv'))
+      io.string
+    end
+
+    private
+
+    def write_entry io, entry
+      path = entry.path.b
+      data = entry.data.b
+      crc32 = Zlib.crc32(data)
+      dos_time, dos_date = dos_timestamp(entry.mtime)
+      offset = io.pos
+
+      local_header = [0x04034b50, VERSION_NEEDED, GP_FLAG, COMPRESSION_STORE,
+                      dos_time, dos_date, crc32, data.bytesize, data.bytesize,
+                      path.bytesize, 0].pack('VvvvvvVVVvv')
+
+      io.write(local_header)
+      io.write(path)
+      io.write(data)
+
+      @central_directory << central_header(path:, crc32:, size: data.bytesize,
+                                           dos_time:, dos_date:, offset:)
+    end
+
+    def central_header path:, crc32:, size:, dos_time:, dos_date:, offset:
+      [0x02014b50, VERSION_NEEDED, VERSION_NEEDED, GP_FLAG, COMPRESSION_STORE,
+       dos_time, dos_date, crc32, size, size, path.bytesize, 0, 0, 0, 0, 0,
+       offset].pack('VvvvvvvVVVvvvvvVV') + path
+    end
+
+    def dos_timestamp time
+      local = time.to_time
+      dos_time = (local.hour << 11) | (local.min << 5) | (local.sec / 2)
+      dos_date = ((local.year - 1980) << 9) | (local.month << 5) | local.day
+      [dos_time, dos_date]
+    end
+  end
+end

backend/app/services/post_version_recorder.rb

@@ -23,6 +23,7 @@ class PostVersionRecorder < VersionRecorder
     { title: @record.title,
       url: @record.url,
       thumbnail_base: @record.thumbnail_base,
+      video_ms: @record.video_ms,
       tags: @record.snapshot_tag_names.join(' '),
       parent_post_ids: @record.snapshot_parent_post_ids.join(' '),
       original_created_from: @record.original_created_from,

backend/app/services/preview/html_metadata_extractor.rb

@@ -0,0 +1,21 @@
+module Preview
+  class HtmlMetadataExtractor
+    IMAGE_SELECTORS = [
+      'meta[property="og:image"]',
+      'meta[name="twitter:image"]',
+      'meta[name="thumbnail"]'
+    ].freeze
+
+    def self.extract(response)
+      document = Nokogiri::HTML.parse(response.body)
+      image_url = IMAGE_SELECTORS.filter_map {
+        document.at_css(_1)&.[]('content')&.strip.presence
+      }.first
+
+      { title: document.at_css('title')&.text&.strip,
+        image_url: image_url ? URI.join(response.url, image_url).to_s : nil }
+    rescue URI::InvalidURIError
+      { title: document.at_css('title')&.text&.strip, image_url: nil }
+    end
+  end
+end

backend/app/services/preview/http_fetcher.rb

@@ -0,0 +1,122 @@
+require 'net/http'
+require 'json'
+
+module Preview
+  class HttpFetcher
+    class FetchFailed < StandardError; end
+    class FetchTimeout < FetchFailed; end
+    class ResponseTooLarge < FetchFailed; end
+
+    MAX_REDIRECTS = 5
+    DEFAULT_MAX_BYTES = 5.megabytes
+
+    Response = Data.define(:body, :content_type, :url)
+
+    def self.fetch(raw_url, max_bytes: DEFAULT_MAX_BYTES, redirects: MAX_REDIRECTS)
+      uri, addresses = UrlSafety.validate(raw_url)
+      response = request(uri, addresses.first, max_bytes)
+
+      if response.is_a?(Net::HTTPRedirection)
+        location = response['location']
+        if redirects.zero?
+          log_failure(:redirect_limit,
+                      url: uri.to_s,
+                      redirects:,
+                      location:,
+                      content_type: response['content-type'],
+                      content_length: response['content-length'])
+          raise FetchFailed, 'redirect が多すぎます．'
+        end
+
+        if location.blank?
+          log_failure(:blank_redirect_location,
+                      url: uri.to_s,
+                      redirects:,
+                      content_type: response['content-type'],
+                      content_length: response['content-length'])
+          raise FetchFailed, 'redirect 先が不正です．'
+        end
+
+        redirect_url =
+            begin
+              URI.join(uri, location).to_s
+            rescue URI::InvalidURIError => e
+              log_failure(:invalid_redirect_location,
+                          url: uri.to_s,
+                          redirects:,
+                          location:,
+                          error: e.class.name,
+                          message: e.message)
+              raise FetchFailed, 'redirect 先が不正です．'
+            end
+
+        return fetch(redirect_url, max_bytes:, redirects: redirects - 1)
+      end
+
+      unless response.is_a?(Net::HTTPSuccess)
+        log_failure(:http_status,
+                    url: uri.to_s,
+                    code: response.code,
+                    content_type: response['content-type'],
+                    content_length: response['content-length'])
+        raise FetchFailed, "外部サーバーが HTTP #{ response.code } を返しました．"
+      end
+
+      Response.new(response.body, response['content-type'].to_s, uri.to_s)
+    rescue Net::OpenTimeout, Net::ReadTimeout, Timeout::Error => e
+      log_failure(:timeout, url: uri&.to_s || raw_url, error: e.class.name, message: e.message)
+      raise FetchTimeout, e.message
+    rescue SocketError, SystemCallError, OpenSSL::SSL::SSLError, EOFError => e
+      log_failure(:network_error, url: uri&.to_s || raw_url, error: e.class.name, message: e.message)
+      raise FetchFailed, e.message
+    end
+
+    def self.request(uri, ip_address, max_bytes)
+      http = Net::HTTP.new(uri.host, uri.port)
+      http.ipaddr = ip_address
+      http.use_ssl = uri.scheme == 'https'
+      http.open_timeout = 5
+      http.read_timeout = 8
+      http.write_timeout = 5
+
+      request = Net::HTTP::Get.new(uri)
+      request['User-Agent'] = 'BTRC-Hub thumbnail preview'
+      request['Accept'] = 'text/html,image/*;q=0.9,*/*;q=0.1'
+
+      http.request(request) do |response|
+        length = response['content-length'].to_i
+        if length > max_bytes
+          log_failure(:response_too_large,
+                      url: uri.to_s,
+                      content_type: response['content-type'],
+                      content_length: response['content-length'],
+                      max_bytes:)
+          raise ResponseTooLarge, '外部データが大きすぎます．'
+        end
+
+        body = +''
+        response.read_body do |chunk|
+          body << chunk
+          next unless body.bytesize > max_bytes
+
+          log_failure(:response_too_large,
+                      url: uri.to_s,
+                      content_type: response['content-type'],
+                      content_length: response['content-length'],
+                      bytes_read: body.bytesize,
+                      max_bytes:)
+          raise ResponseTooLarge, '外部データが大きすぎます．'
+        end
+        response.instance_variable_set(:@body, body)
+        response.instance_variable_set(:@read, true)
+        return response
+      end
+    end
+
+    def self.log_failure(reason, **payload)
+      Rails.logger.warn("preview_http_fetcher_failure #{ { reason:, **payload }.to_json }")
+    end
+
+    private_class_method :request, :log_failure
+  end
+end

backend/app/services/preview/known_site_extractor.rb

@@ -0,0 +1,31 @@
+module Preview
+  class KnownSiteExtractor
+    def self.thumbnail_url(uri)
+      youtube_thumbnail(uri)
+    end
+
+    def self.niconico_video_id(uri)
+      case uri.host&.downcase
+      when 'www.nicovideo.jp', 'nicovideo.jp'
+        uri.path[%r{\A/watch/(sm\d+)\z}, 1]
+      when 'nico.ms'
+        uri.path[%r{\A/(sm\d+)\z}, 1]
+      end
+    end
+
+    def self.youtube_thumbnail(uri)
+      id =
+          case uri.host&.downcase
+          when 'youtu.be'
+            uri.path.split('/').reject(&:blank?).first
+          when 'www.youtube.com', 'youtube.com', 'm.youtube.com'
+            uri.path == '/watch' ? URI.decode_www_form(uri.query.to_s).to_h['v'] : nil
+          end
+      return unless id&.match?(/\A[A-Za-z0-9_-]{6,20}\z/)
+
+      "https://i.ytimg.com/vi/#{ id }/hqdefault.jpg"
+    end
+
+    private_class_method :youtube_thumbnail
+  end
+end

backend/app/services/preview/thumbnail_fetcher.rb

@@ -0,0 +1,95 @@
+module Preview
+  class ThumbnailFetcher
+    class GenerationFailed < StandardError; end
+    ALLOWED_IMAGE_CONTENT_TYPES = [
+      'image/jpeg', 'image/png', 'image/gif', 'image/webp'
+    ].freeze
+    HTML_MAX_BYTES = 1.megabyte
+    NICONICO_XML_MAX_BYTES = 256.kilobytes
+
+    def self.fetch(raw_url)
+      uri, = UrlSafety.validate(raw_url)
+
+      known_url = KnownSiteExtractor.thumbnail_url(uri)
+      image = fetch_image_or_nil(known_url) if known_url
+      return image if image
+
+      niconico_url = niconico_thumbnail_url(uri)
+      image = fetch_image_or_nil(niconico_url) if niconico_url
+      return image if image
+
+      page = HttpFetcher.fetch(uri.to_s, max_bytes: HTML_MAX_BYTES)
+      metadata = HtmlMetadataExtractor.extract(page)
+      raise GenerationFailed, 'サムネール画像が見つかりませんでした．' if metadata[:image_url].blank?
+
+      fetch_image!(metadata[:image_url])
+    end
+
+    def self.title(raw_url)
+      uri, = UrlSafety.validate(raw_url)
+      HtmlMetadataExtractor.extract(
+          HttpFetcher.fetch(uri.to_s, max_bytes: HTML_MAX_BYTES))[:title]
+    end
+
+    def self.fetch_image_or_nil(url)
+      return nil if url.blank?
+
+      response = HttpFetcher.fetch(url)
+      return nil unless allowed_image_content_type?(response.content_type)
+
+      response.body
+    rescue HttpFetcher::FetchTimeout
+      raise
+    rescue HttpFetcher::FetchFailed
+      nil
+    end
+
+    def self.fetch_image!(url)
+      response = HttpFetcher.fetch(url)
+      unless allowed_image_content_type?(response.content_type)
+        raise GenerationFailed, 'サムネール画像が見つかりませんでした．'
+      end
+
+      response.body
+    rescue HttpFetcher::FetchTimeout
+      raise
+    rescue HttpFetcher::ResponseTooLarge
+      raise
+    rescue HttpFetcher::FetchFailed
+      raise GenerationFailed, 'サムネール画像を取得できませんでした．'
+    end
+
+    def self.niconico_thumbnail_url(uri)
+      video_id = KnownSiteExtractor.niconico_video_id(uri)
+      return nil if video_id.blank?
+
+      response = HttpFetcher.fetch("https://ext.nicovideo.jp/api/getthumbinfo/#{ video_id }",
+                                   max_bytes: NICONICO_XML_MAX_BYTES)
+      xml = Nokogiri::XML(response.body)
+      return nil unless xml.at_xpath('/nicovideo_thumb_response/@status')&.value == 'ok'
+
+      xml.at_xpath('//thumbnail_url')&.text&.strip.presence
+    rescue HttpFetcher::FetchFailed, HttpFetcher::FetchTimeout => e
+      Rails.logger.info("preview_niconico_getthumbinfo_fallback #{ { url: uri.to_s,
+                                                                     video_id:,
+                                                                     error: e.class.name,
+                                                                     message: e.message }.to_json }")
+      nil
+    rescue Nokogiri::XML::SyntaxError => e
+      Rails.logger.info("preview_niconico_getthumbinfo_fallback #{ { url: uri.to_s,
+                                                                     video_id:,
+                                                                     error: e.class.name,
+                                                                     message: e.message }.to_json }")
+      nil
+    end
+
+    def self.allowed_image_content_type?(content_type)
+      mime_type = content_type.to_s.split(';', 2).first.downcase.strip
+      ALLOWED_IMAGE_CONTENT_TYPES.include?(mime_type)
+    end
+
+    private_class_method :fetch_image_or_nil, :fetch_image!,
+                         :niconico_thumbnail_url,
+                         :allowed_image_content_type?
+  end
+end

backend/app/services/preview/url_safety.rb

@@ -0,0 +1,55 @@
+require 'resolv'
+require 'ipaddr'
+require 'uri'
+
+module Preview
+  class UrlSafety
+    class UnsafeUrl < StandardError; end
+
+    FORBIDDEN_NETWORKS = [
+      '0.0.0.0/8', '10.0.0.0/8', '100.64.0.0/10', '127.0.0.0/8',
+      '169.254.0.0/16', '172.16.0.0/12', '192.0.0.0/24',
+      '192.0.2.0/24', '192.168.0.0/16', '198.18.0.0/15',
+      '198.51.100.0/24', '203.0.113.0/24', '224.0.0.0/4',
+      '240.0.0.0/4', '::/128', '::1/128', 'fc00::/7', 'fe80::/10',
+      'ff00::/8', '2001:db8::/32', '::ffff:0:0/96'
+    ].map { IPAddr.new(_1) }.freeze
+
+    def self.validate(raw_url)
+      value = raw_url.to_s.strip
+      if value.match?(/\A[a-z][a-z0-9+\-.]*:/i)
+        unless value.match?(/\Ahttps?:\/\//i)
+          raise UnsafeUrl, 'http または https の URL を指定してください．'
+        end
+      else
+        value = "http://#{ value }"
+      end
+      uri = URI.parse(value)
+
+      unless ['http', 'https'].include?(uri.scheme&.downcase) && uri.host.present?
+        raise UnsafeUrl, 'http または https の URL を指定してください．'
+      end
+      raise UnsafeUrl, 'userinfo つき URL は使用できません．' if uri.userinfo.present?
+
+      addresses = Resolv.getaddresses(uri.host)
+      raise UnsafeUrl, 'URL のホストを解決できません．' if addresses.empty?
+
+      parsed_addresses = addresses.map { IPAddr.new(_1) }
+      if parsed_addresses.any? { |address| forbidden?(address) }
+        raise UnsafeUrl, '安全でない接続先は使用できません．'
+      end
+
+      [uri, parsed_addresses.map(&:to_s)]
+    rescue Resolv::ResolvError
+      raise UnsafeUrl, 'URL のホストを解決できません．'
+    rescue URI::InvalidURIError, IPAddr::InvalidAddressError
+      raise UnsafeUrl, 'URL が不正です．'
+    end
+
+    def self.forbidden?(address)
+      FORBIDDEN_NETWORKS.any? { _1.include?(address) }
+    end
+
+    private_class_method :forbidden?
+  end
+end

backend/app/services/similarity/calc.rb

@@ -1,6 +1,6 @@
 module Similarity
   class Calc
-    def self.call model, tgt
+    def self.call model, tgt, scope: nil
       similarity_model = "#{ model.name }Similarity".constantize
 
       # 最大保存件数
@@ -8,7 +8,8 @@ module Similarity
 
       similarity_model.delete_all
 
-      posts = model.includes(tgt).select(:id).to_a
+      scope ||= model.all
+      posts = scope.includes(tgt).select(:id).to_a
 
       tag_ids = { }
       tag_cnts = { }

backend/app/services/tag_version_recorder.rb

@@ -16,6 +16,7 @@ class TagVersionRecorder < VersionRecorder
   def snapshot_attributes
     { name: @record.name,
       category: @record.category,
+      deprecated_at: @record.deprecated_at,
       aliases: @record.snapshot_aliases.join(' '),
       parent_tag_ids: @record.snapshot_parent_tag_ids.join(' ') }
   end

backend/app/services/version_recorder.rb

@@ -73,7 +73,7 @@ class VersionRecorder
   end
 
   def validate_event_type!
-    return if EVENT_TYPES.include?(@event_type)
+    return if event_types.include?(@event_type)
 
     raise ArgumentError, "Invalid event_type: #{ @event_type }"
   end
@@ -84,4 +84,5 @@ class VersionRecorder
   def snapshot_attributes = raise NotImplementedError
 
   def record_class = @record.class
+  def event_types = self.class::EVENT_TYPES
 end

backend/config/routes.rb

@@ -81,6 +81,11 @@ Rails.application.routes.draw do
     end
   end
 
+  get 'users/settings', to: 'user_settings#show'
+  patch 'users/settings', to: 'user_settings#update'
+  get 'users/theme_slots', to: 'user_theme_slots#index'
+  put 'users/theme_slots/:base_theme/:slot_no', to: 'user_theme_slots#update'
+
   resources :users, only: [:create, :update] do
     collection do
       post :verify
@@ -113,5 +118,8 @@ Rails.application.routes.draw do
     resources :skip_events, controller: :theatre_skip_events, only: [:index]
   end
 
+  get 'materials/download.zip', to: 'materials#download'
+  get 'materials/versions', to: 'material_versions#index'
+  resources :material_sync_suppressions, path: 'materials/suppressions', only: [:index, :create]
   resources :materials, only: [:index, :show, :create, :update, :destroy]
 end

backend/db/migrate/20260519013100_add_video_ms_to_posts.rb

@@ -0,0 +1,9 @@
+class AddVideoMsToPosts < ActiveRecord::Migration[8.0]
+  def change
+    add_column :posts, :video_ms, :integer
+    add_index :posts, [:video_ms, :id], name: 'idx_posts_video_ms_id'
+
+    add_check_constraint :posts, 'video_ms IS NULL OR video_ms > 0',
+                         name: 'chk_posts_video_ms_positive'
+  end
+end

backend/db/migrate/20260621000000_add_deprecated_at_to_tags.rb

@@ -0,0 +1,20 @@
+class AddDeprecatedAtToTags < ActiveRecord::Migration[8.0]
+  def up
+    add_column :tags, :deprecated_at, :datetime, after: :category
+    add_column :tag_versions, :deprecated_at, :datetime, after: :parent_tag_ids
+
+    add_index :tags, :deprecated_at
+
+    add_check_constraint :tags, "deprecated_at IS NULL OR category <> 'nico'",
+                         name: 'chk_tags_deprecated_at_not_nico'
+  end
+
+  def down
+    remove_check_constraint :tags, name: 'chk_tags_deprecated_at_not_nico'
+
+    remove_index :tags, :deprecated_at
+
+    remove_column :tag_versions, :deprecated_at, :datetime
+    remove_column :tags, :deprecated_at
+  end
+end

backend/db/migrate/20260622010000_create_post_tag_sections.rb

@@ -0,0 +1,19 @@
+class CreatePostTagSections < ActiveRecord::Migration[8.0]
+  def change
+    create_table :post_tag_sections, primary_key: [:post_id, :tag_id, :begin_ms] do |t|
+      t.references :post, null: false, foreign_key: true, index: false
+      t.references :tag, null: false, foreign_key: true, index: false
+      t.integer :begin_ms, null: false
+      t.integer :end_ms, null: true
+      t.timestamps
+
+      t.index [:post_id, :begin_ms], name: 'idx_post_tag_sections_post_id_begin_ms'
+
+      t.check_constraint 'begin_ms >= 0',
+                         name: 'chk_post_tag_sections_begin_ms_natural'
+
+      t.check_constraint 'end_ms IS NULL OR begin_ms < end_ms',
+                         name: 'chk_post_tag_sections_end_ms_after_begin_ms'
+    end
+  end
+end

backend/db/migrate/20260622020000_add_video_ms_to_post_versions.rb

@@ -0,0 +1,9 @@
+class AddVideoMsToPostVersions < ActiveRecord::Migration[8.0]
+  def change
+    add_column :post_versions, :video_ms, :integer
+    add_index :post_versions, [:video_ms, :post_id], name: 'idx_post_versions_video_ms_post_id'
+
+    add_check_constraint :post_versions, 'video_ms IS NULL OR video_ms > 0',
+                         name: 'chk_post_versions_video_ms_positive'
+  end
+end

backend/db/migrate/20260623000000_enhance_material_management.rb

@@ -0,0 +1,88 @@
+class EnhanceMaterialManagement < ActiveRecord::Migration[8.0]
+  def up
+    change_table :materials, bulk: true do |t|
+      t.integer :version_no, null: false, default: 1
+    end
+
+    change_table :material_versions, bulk: true do |t|
+      t.string :event_type
+      t.string :tag_name
+      t.string :tag_category
+      t.json :export_paths_json
+      t.bigint :file_blob_id
+      t.string :file_filename
+      t.string :file_content_type
+      t.bigint :file_byte_size
+      t.string :file_checksum
+      t.string :file_sha256
+    end
+
+    execute <<~SQL.squish
+      UPDATE material_versions
+      SET event_type = CASE
+                       WHEN version_no = 1 THEN 'create'
+                       ELSE 'update'
+                       END
+      WHERE event_type IS NULL
+    SQL
+
+    change_column_null :material_versions, :event_type, false
+    add_index :material_versions, :file_blob_id
+
+    add_check_constraint :material_versions,
+                         "event_type IN ('create', 'update', 'discard', 'restore')",
+                         name: 'material_versions_event_type_valid'
+
+    create_table :material_export_items do |t|
+      t.references :material, null: false, foreign_key: true
+      t.string :profile, null: false, default: 'legacy_drive'
+      t.string :export_path, null: false
+      t.boolean :enabled, null: false, default: true
+      t.references :created_by_user, foreign_key: { to_table: :users }
+      t.timestamps
+
+      t.index [:profile, :export_path], unique: true
+      t.index [:material_id, :profile], unique: true
+    end
+
+    create_table :material_import_blocks do |t|
+      t.string :match_kind, null: false
+      t.string :sha256
+      t.string :external_path_pattern
+      t.string :reason, null: false
+      t.text :note
+      t.references :created_by_user, foreign_key: { to_table: :users }
+      t.timestamps
+    end
+
+    execute <<~SQL.squish
+      UPDATE materials
+      SET version_no = COALESCE(
+        (SELECT MAX(material_versions.version_no)
+         FROM material_versions
+         WHERE material_versions.material_id = materials.id),
+        1)
+    SQL
+  end
+
+  def down
+    drop_table :material_import_blocks
+    drop_table :material_export_items
+
+    remove_check_constraint :material_versions, name: 'material_versions_event_type_valid'
+
+    remove_index :material_versions, :file_blob_id
+    remove_column :material_versions, :event_type
+    remove_column :material_versions, :tag_name
+    remove_column :material_versions, :tag_category
+    remove_column :material_versions, :export_paths_json
+    remove_column :material_versions, :file_blob_id
+    remove_column :material_versions, :file_filename
+    remove_column :material_versions, :file_content_type
+    remove_column :material_versions, :file_byte_size
+    remove_column :material_versions, :file_checksum
+    remove_column :material_versions, :file_sha256
+
+    remove_column :materials, :version_no
+  end
+end

backend/db/migrate/20260625000000_reconcile_material_sync_suppressions.rb

@@ -0,0 +1,118 @@
+class ReconcileMaterialSyncSuppressions < ActiveRecord::Migration[8.0]
+  MATERIAL_VERSION_EVENT_CONSTRAINT = 'material_versions_event_type_valid'
+
+  def up
+    ensure_material_sync_suppressions!
+    ensure_material_source_columns!
+    ensure_material_active_source_key!
+    remove_material_file_suppression!
+    remove_material_version_file_suppression!
+    reconcile_material_version_event_constraint!
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+
+  private
+
+  def ensure_material_sync_suppressions!
+    return if table_exists?(:material_sync_suppressions)
+
+    create_table :material_sync_suppressions do |t|
+      t.string :source_kind, null: false
+      t.string :source_uri
+      t.string :drive_path
+      t.string :drive_file_id
+      t.string :normalized_source_key, null: false
+      t.string :reason, null: false
+      t.references :created_by_user, foreign_key: { to_table: :users }
+      t.timestamps
+
+      t.index :normalized_source_key, unique: true
+      t.index :source_kind
+      t.index :drive_file_id
+    end
+  end
+
+  def ensure_material_source_columns!
+    add_column :materials, :source_kind, :string unless column_exists?(:materials, :source_kind)
+    add_column :materials, :source_uri, :string unless column_exists?(:materials, :source_uri)
+    add_column :materials, :source_path, :string unless column_exists?(:materials, :source_path)
+    unless column_exists?(:materials, :source_file_id)
+      add_column :materials, :source_file_id, :string
+    end
+    unless column_exists?(:materials, :normalized_source_key)
+      add_column :materials, :normalized_source_key, :string
+    end
+
+    if index_exists?(:materials, :normalized_source_key)
+      remove_index :materials, column: :normalized_source_key
+    end
+  end
+
+  def ensure_material_active_source_key!
+    unless column_exists?(:materials, :active_normalized_source_key)
+      change_table :materials do |t|
+        t.virtual :active_normalized_source_key,
+                  type: :string,
+                  as: 'IF(discarded_at IS NULL, normalized_source_key, NULL)',
+                  stored: false
+      end
+    end
+
+    return if index_exists?(:materials,
+                            :active_normalized_source_key,
+                            name: 'index_materials_on_active_normalized_source_key')
+
+    add_index :materials,
+              :active_normalized_source_key,
+              unique: true,
+              name: 'index_materials_on_active_normalized_source_key'
+  end
+
+  def remove_material_file_suppression!
+    if foreign_key_exists?(:materials, :users, column: :file_suppressed_by_user_id)
+      remove_foreign_key :materials, column: :file_suppressed_by_user_id
+    end
+
+    if index_exists?(:materials,
+                    :file_suppressed_by_user_id,
+                    name: 'index_materials_on_file_suppressed_by_user_id')
+      remove_index :materials, name: 'index_materials_on_file_suppressed_by_user_id'
+    end
+
+    remove_column :materials, :file_suppressed_at if column_exists?(
+        :materials,
+        :file_suppressed_at)
+    remove_column :materials, :file_suppressed_by_user_id if column_exists?(
+        :materials,
+        :file_suppressed_by_user_id)
+    remove_column :materials, :file_suppression_reason if column_exists?(
+        :materials,
+        :file_suppression_reason)
+  end
+
+  def remove_material_version_file_suppression!
+    remove_column :material_versions, :file_suppressed_at if column_exists?(
+        :material_versions,
+        :file_suppressed_at)
+    remove_column :material_versions, :file_suppression_reason if column_exists?(
+        :material_versions,
+        :file_suppression_reason)
+  end
+
+  def reconcile_material_version_event_constraint!
+    constraint = check_constraints(:material_versions).find do |candidate|
+      candidate.name == MATERIAL_VERSION_EVENT_CONSTRAINT
+    end
+    return if constraint && !constraint.expression.include?('suppress')
+
+    if constraint
+      remove_check_constraint :material_versions, name: MATERIAL_VERSION_EVENT_CONSTRAINT
+    end
+    add_check_constraint :material_versions,
+                         "event_type IN ('create', 'update', 'discard', 'restore')",
+                         name: MATERIAL_VERSION_EVENT_CONSTRAINT
+  end
+end

backend/db/migrate/20260625010000_create_material_sync_sources.rb

@@ -0,0 +1,22 @@
+class CreateMaterialSyncSources < ActiveRecord::Migration[8.0]
+  def change
+    create_table :material_sync_sources do |t|
+      t.string :name, null: false
+      t.string :source_kind, null: false
+      t.string :source_uri
+      t.string :source_path
+      t.string :source_file_id
+      t.string :profile, null: false, default: 'legacy_drive'
+      t.boolean :enabled, null: false, default: true
+      t.string :default_tag_name
+      t.string :export_path_prefix
+      t.datetime :last_synced_at
+      t.references :created_by_user, foreign_key: { to_table: :users }
+      t.references :updated_by_user, foreign_key: { to_table: :users }
+      t.timestamps
+
+      t.index :enabled
+      t.index :source_kind
+    end
+  end
+end

backend/db/migrate/20260626000000_add_source_snapshot_to_material_versions.rb

@@ -0,0 +1,19 @@
+class AddSourceSnapshotToMaterialVersions < ActiveRecord::Migration[8.0]
+  def change
+    unless column_exists?(:material_versions, :source_kind)
+      add_column :material_versions, :source_kind, :string
+    end
+    unless column_exists?(:material_versions, :source_uri)
+      add_column :material_versions, :source_uri, :string
+    end
+    unless column_exists?(:material_versions, :source_path)
+      add_column :material_versions, :source_path, :string
+    end
+    unless column_exists?(:material_versions, :source_file_id)
+      add_column :material_versions, :source_file_id, :string
+    end
+    unless column_exists?(:material_versions, :normalized_source_key)
+      add_column :material_versions, :normalized_source_key, :string
+    end
+  end
+end

backend/db/migrate/20260626010000_backfill_initial_material_versions.rb

@@ -0,0 +1,171 @@
+require 'json'
+
+class BackfillInitialMaterialVersions < ActiveRecord::Migration[8.0]
+  class MigrationMaterial < ActiveRecord::Base
+    self.table_name = 'materials'
+  end
+
+  class MigrationMaterialExportItem < ActiveRecord::Base
+    self.table_name = 'material_export_items'
+  end
+
+  class MigrationMaterialVersion < ActiveRecord::Base
+    self.table_name = 'material_versions'
+  end
+
+  class MigrationStorageAttachment < ActiveRecord::Base
+    self.table_name = 'active_storage_attachments'
+  end
+
+  class MigrationStorageBlob < ActiveRecord::Base
+    self.table_name = 'active_storage_blobs'
+  end
+
+  class MigrationTag < ActiveRecord::Base
+    self.table_name = 'tags'
+  end
+
+  class MigrationTagName < ActiveRecord::Base
+    self.table_name = 'tag_names'
+  end
+
+  def up
+    say_with_time 'Backfilling initial material versions' do
+      materials_without_versions.find_in_batches(batch_size: 500) do |materials|
+        material_ids = materials.map(&:id)
+        tags_by_id = load_tags(materials.map(&:tag_id).compact.uniq)
+        export_paths_by_material_id = load_export_paths(material_ids)
+        file_snapshots_by_material_id = load_file_snapshots(material_ids)
+
+        rows = materials.map do |material|
+          tag = tags_by_id[material.tag_id]
+          file_snapshot = file_snapshots_by_material_id[material.id] || empty_file_snapshot
+
+          { material_id: material.id,
+            version_no: 1,
+            event_type: 'create',
+            url: material.url,
+            parent_id: material.parent_id,
+            tag_id: material.tag_id,
+            tag_name: tag&.fetch(:name, nil),
+            tag_category: tag&.fetch(:category, nil),
+            source_kind: material.source_kind,
+            source_uri: material.source_uri,
+            source_path: material.source_path,
+            source_file_id: material.source_file_id,
+            normalized_source_key: material.normalized_source_key,
+            export_paths_json: export_paths_by_material_id[material.id] || { },
+            discarded_at: material.discarded_at,
+            file_blob_id: file_snapshot[:file_blob_id],
+            file_filename: file_snapshot[:file_filename],
+            file_content_type: file_snapshot[:file_content_type],
+            file_byte_size: file_snapshot[:file_byte_size],
+            file_checksum: file_snapshot[:file_checksum],
+            file_sha256: file_snapshot[:file_sha256],
+            created_by_user_id: material.created_by_user_id,
+            updated_by_user_id: material.updated_by_user_id,
+            created_at: material.created_at,
+            updated_at: material.created_at }
+        end
+
+        MigrationMaterialVersion.insert_all!(rows) if rows.present?
+      end
+    end
+
+    execute <<~SQL.squish
+      UPDATE materials
+      SET version_no = COALESCE(
+        (
+          SELECT MAX(material_versions.version_no)
+          FROM material_versions
+          WHERE material_versions.material_id = materials.id
+        ),
+        1
+      )
+    SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+
+  private
+
+  def materials_without_versions
+    MigrationMaterial.where.not(id: MigrationMaterialVersion.select(:material_id))
+  end
+
+  def load_tags tag_ids
+    return { } if tag_ids.empty?
+
+    tag_name_ids_by_tag_id = MigrationTag.where(id: tag_ids).pluck(:id, :tag_name_id).to_h
+    tag_names_by_id =
+        MigrationTagName
+        .where(id: tag_name_ids_by_tag_id.values.uniq)
+        .pluck(:id, :name)
+        .to_h
+    categories_by_tag_id = MigrationTag.where(id: tag_ids).pluck(:id, :category).to_h
+
+    tag_ids.each_with_object({ }) do |tag_id, hash|
+      hash[tag_id] = { name: tag_names_by_id[tag_name_ids_by_tag_id[tag_id]],
+                       category: categories_by_tag_id[tag_id] }
+    end
+  end
+
+  def load_export_paths material_ids
+    MigrationMaterialExportItem
+      .where(material_id: material_ids)
+      .order(:material_id, :profile)
+      .pluck(:material_id, :profile, :export_path)
+      .each_with_object({ }) do |(material_id, profile, export_path), hash|
+        hash[material_id] ||= { }
+        hash[material_id][profile] = export_path
+      end
+  end
+
+  def load_file_snapshots material_ids
+    attachments_by_material_id =
+        MigrationStorageAttachment
+        .where(record_type: 'Material', name: 'file', record_id: material_ids)
+        .pluck(:record_id, :blob_id)
+        .to_h
+
+    blobs_by_id =
+        MigrationStorageBlob
+        .where(id: attachments_by_material_id.values.uniq)
+        .index_by(&:id)
+
+    attachments_by_material_id.each_with_object({ }) do |(material_id, blob_id), hash|
+      blob = blobs_by_id[blob_id]
+      next unless blob
+
+      hash[material_id] = {
+        file_blob_id: blob.id,
+        file_filename: blob.filename.to_s,
+        file_content_type: blob.content_type,
+        file_byte_size: blob.byte_size,
+        file_checksum: blob.checksum,
+        file_sha256: blob_metadata(blob)['sha256']
+      }
+    end
+  end
+
+  def empty_file_snapshot
+    { file_blob_id: nil,
+      file_filename: nil,
+      file_content_type: nil,
+      file_byte_size: nil,
+      file_checksum: nil,
+      file_sha256: nil }
+  end
+
+  def blob_metadata blob
+    metadata = blob.metadata
+    return metadata if metadata.is_a?(Hash)
+    return { } if metadata.blank?
+
+    JSON.parse(metadata)
+  rescue JSON::ParserError
+    { }
+  end
+end

backend/db/migrate/20260704000000_rebuild_settings_as_typed_user_settings.rb

@@ -0,0 +1,31 @@
+class RebuildSettingsAsTypedUserSettings < ActiveRecord::Migration[8.0]
+  def change
+    remove_foreign_key :settings, :users if foreign_key_exists?(:settings, :users)
+    remove_index :settings, :user_id if index_exists?(:settings, :user_id)
+
+    remove_column :settings, :key, :string if column_exists?(:settings, :key)
+    remove_column :settings, :value, :json if column_exists?(:settings, :value)
+
+    change_column_null :settings, :user_id, false
+
+    add_column :settings, :theme, :string, null: false, default: 'system'
+    add_column :settings,
+               :auto_fetch_title,
+               :string,
+               null: false,
+               default: 'manual'
+    add_column :settings,
+               :auto_fetch_thumbnail,
+               :string,
+               null: false,
+               default: 'manual'
+    add_column :settings,
+               :wiki_editor_mode,
+               :string,
+               null: false,
+               default: 'split'
+
+    add_index :settings, :user_id, unique: true
+    add_foreign_key :settings, :users
+  end
+end

backend/db/migrate/20260705000000_create_user_theme_slots.rb

@@ -0,0 +1,22 @@
+class CreateUserThemeSlots < ActiveRecord::Migration[8.0]
+  def change
+    create_table :user_theme_slots do |t|
+      t.references :user, null: false, foreign_key: true
+      t.string :base_theme, null: false
+      t.integer :slot_no, null: false
+      t.json :tokens, null: false
+      t.timestamps
+    end
+
+    add_index :user_theme_slots,
+              [:user_id, :base_theme, :slot_no],
+              unique: true,
+              name: 'index_user_theme_slots_on_user_theme_and_slot'
+    add_check_constraint :user_theme_slots,
+                         "base_theme IN ('light', 'dark')",
+                         name: 'user_theme_slots_base_theme_valid'
+    add_check_constraint :user_theme_slots,
+                         'slot_no BETWEEN 1 AND 3',
+                         name: 'user_theme_slots_slot_no_valid'
+  end
+end

backend/db/migrate/20260713000000_create_post_url_sanitisation_rules.rb

@@ -0,0 +1,47 @@
+class CreatePostUrlSanitisationRules < ActiveRecord::Migration[8.0]
+  def up
+    create_table :post_url_sanitisation_rules,
+                 id: :integer,
+                 primary_key: :priority do |t|
+      t.string :source_pattern, null: false
+      t.string :replacement, null: false
+      t.timestamps
+      t.datetime :discarded_at
+      t.index :source_pattern, unique: true
+      t.index :discarded_at
+    end
+
+    now = ActiveRecord::Base.connection.quote(Time.current)
+    execute <<~SQL
+      INSERT INTO
+        post_url_sanitisation_rules(priority, source_pattern, replacement, created_at, updated_at)
+      VALUES
+        (10, '\\Ahttps?://youtu\\\\.be/([^/?#]+)(?:[?#].*)?\\z',
+             'https://www.youtube.com/watch?v=\\\\1',
+             #{ now }, #{ now })
+      , (20, '\\Ahttps?://(?:www\\\\.|m\\\\.)?youtube\\\\.com/live/([^/?#]+)(?:[?#].*)?\\z',
+             'https://www.youtube.com/watch?v=\\\\1',
+             #{ now }, #{ now })
+      , (30, '\\Ahttps?://(?:www\\\\.|m\\\\.)?youtube\\\\.com/shorts/([^/?#]+)(?:[?#].*)?\\z',
+             'https://www.youtube.com/watch?v=\\\\1',
+             #{ now }, #{ now })
+      , (40, '\\Ahttps?://(?:www\\\\.|m\\\\.)?youtube\\\\.com/embed/([^/?#]+)(?:[?#].*)?\\z',
+             'https://www.youtube.com/watch?v=\\\\1',
+             #{ now }, #{ now })
+      , (50, '\\Ahttps?://(?:www\\\\.|m\\\\.)?youtube\\\\.com/watch\\\\?(?:[^#&]+&)*v=([^&#]+)(?:[&#].*)?\\z',
+             'https://www.youtube.com/watch?v=\\\\1',
+             #{ now }, #{ now })
+      , (60, '\\Ahttps?://nico\\\\.ms/([^/?#]+)(?:[?#].*)?\\z',
+             'https://www.nicovideo.jp/watch/\\\\1',
+             #{ now }, #{ now })
+      , (70, '\\Ahttps?://(?:www\\\\.)?nicovideo\\\\.jp/watch/([^?#/]+)(?:[?#].*)?\\z',
+             'https://www.nicovideo.jp/watch/\\\\1',
+             #{ now }, #{ now })
+      ;
+    SQL
+  end
+
+  def down
+    drop_table :post_url_sanitisation_rules
+  end
+end

backend/db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
+ActiveRecord::Schema[8.0].define(version: 2026_07_13_000000) do
   create_table "active_storage_attachments", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
@@ -130,6 +130,69 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
     t.index ["ip_address"], name: "index_ip_addresses_on_ip_address", unique: true
   end
 
+  create_table "material_export_items", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "material_id", null: false
+    t.string "profile", default: "legacy_drive", null: false
+    t.string "export_path", null: false
+    t.boolean "enabled", default: true, null: false
+    t.bigint "created_by_user_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["created_by_user_id"], name: "index_material_export_items_on_created_by_user_id"
+    t.index ["material_id", "profile"], name: "index_material_export_items_on_material_id_and_profile", unique: true
+    t.index ["material_id"], name: "index_material_export_items_on_material_id"
+    t.index ["profile", "export_path"], name: "index_material_export_items_on_profile_and_export_path", unique: true
+  end
+
+  create_table "material_import_blocks", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "match_kind", null: false
+    t.string "sha256"
+    t.string "external_path_pattern"
+    t.string "reason", null: false
+    t.text "note"
+    t.bigint "created_by_user_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["created_by_user_id"], name: "index_material_import_blocks_on_created_by_user_id"
+  end
+
+  create_table "material_sync_sources", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "name", null: false
+    t.string "source_kind", null: false
+    t.string "source_uri"
+    t.string "source_path"
+    t.string "source_file_id"
+    t.string "profile", default: "legacy_drive", null: false
+    t.boolean "enabled", default: true, null: false
+    t.string "default_tag_name"
+    t.string "export_path_prefix"
+    t.datetime "last_synced_at"
+    t.bigint "created_by_user_id"
+    t.bigint "updated_by_user_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["created_by_user_id"], name: "index_material_sync_sources_on_created_by_user_id"
+    t.index ["enabled"], name: "index_material_sync_sources_on_enabled"
+    t.index ["source_kind"], name: "index_material_sync_sources_on_source_kind"
+    t.index ["updated_by_user_id"], name: "index_material_sync_sources_on_updated_by_user_id"
+  end
+
+  create_table "material_sync_suppressions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "source_kind", null: false
+    t.string "source_uri"
+    t.string "drive_path"
+    t.string "drive_file_id"
+    t.string "normalized_source_key", null: false
+    t.string "reason", null: false
+    t.bigint "created_by_user_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["created_by_user_id"], name: "index_material_sync_suppressions_on_created_by_user_id"
+    t.index ["drive_file_id"], name: "index_material_sync_suppressions_on_drive_file_id"
+    t.index ["normalized_source_key"], name: "index_material_sync_suppressions_on_normalized_source_key", unique: true
+    t.index ["source_kind"], name: "index_material_sync_suppressions_on_source_kind"
+  end
+
   create_table "material_versions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "material_id", null: false
     t.integer "version_no", null: false
@@ -141,14 +204,31 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.datetime "discarded_at"
+    t.string "event_type", null: false
+    t.string "tag_name"
+    t.string "tag_category"
+    t.json "export_paths_json"
+    t.bigint "file_blob_id"
+    t.string "file_filename"
+    t.string "file_content_type"
+    t.bigint "file_byte_size"
+    t.string "file_checksum"
+    t.string "file_sha256"
+    t.string "source_kind"
+    t.string "source_uri"
+    t.string "source_path"
+    t.string "source_file_id"
+    t.string "normalized_source_key"
     t.index ["created_by_user_id"], name: "index_material_versions_on_created_by_user_id"
     t.index ["discarded_at"], name: "index_material_versions_on_discarded_at"
+    t.index ["file_blob_id"], name: "index_material_versions_on_file_blob_id"
     t.index ["material_id", "version_no"], name: "index_material_versions_on_material_id_and_version_no", unique: true
     t.index ["material_id"], name: "index_material_versions_on_material_id"
     t.index ["parent_id"], name: "index_material_versions_on_parent_id"
     t.index ["tag_id"], name: "index_material_versions_on_tag_id"
     t.index ["updated_by_user_id"], name: "index_material_versions_on_updated_by_user_id"
     t.index ["url"], name: "index_material_versions_on_url"
+    t.check_constraint "`event_type` in (_utf8mb4'create',_utf8mb4'update',_utf8mb4'discard',_utf8mb4'restore')", name: "material_versions_event_type_valid"
   end
 
   create_table "materials", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
@@ -161,6 +241,14 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
     t.datetime "updated_at", null: false
     t.datetime "discarded_at"
     t.virtual "active_url", type: :string, as: "if((`discarded_at` is null),`url`,NULL)"
+    t.integer "version_no", default: 1, null: false
+    t.string "source_kind"
+    t.string "source_uri"
+    t.string "source_path"
+    t.string "source_file_id"
+    t.string "normalized_source_key"
+    t.virtual "active_normalized_source_key", type: :string, as: "if((`discarded_at` is null),`normalized_source_key`,NULL)"
+    t.index ["active_normalized_source_key"], name: "index_materials_on_active_normalized_source_key", unique: true
     t.index ["active_url"], name: "index_materials_on_active_url", unique: true
     t.index ["created_by_user_id"], name: "index_materials_on_created_by_user_id"
     t.index ["discarded_at"], name: "index_materials_on_discarded_at"
@@ -210,6 +298,19 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
     t.index ["target_post_id"], name: "index_post_similarities_on_target_post_id"
   end
 
+  create_table "post_tag_sections", primary_key: ["post_id", "tag_id", "begin_ms"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "post_id", null: false
+    t.bigint "tag_id", null: false
+    t.integer "begin_ms", null: false
+    t.integer "end_ms"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["post_id", "begin_ms"], name: "idx_post_tag_sections_post_id_begin_ms"
+    t.index ["tag_id"], name: "fk_rails_8be3847903"
+    t.check_constraint "(`end_ms` is null) or (`begin_ms` < `end_ms`)", name: "chk_post_tag_sections_end_ms_after_begin_ms"
+    t.check_constraint "`begin_ms` >= 0", name: "chk_post_tag_sections_begin_ms_natural"
+  end
+
   create_table "post_tags", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "post_id", null: false
     t.bigint "tag_id", null: false
@@ -230,6 +331,16 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
     t.index ["tag_id"], name: "index_post_tags_on_tag_id"
   end
 
+  create_table "post_url_sanitisation_rules", primary_key: "priority", id: :integer, charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "source_pattern", null: false
+    t.string "replacement", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.datetime "discarded_at"
+    t.index ["discarded_at"], name: "index_post_url_sanitisation_rules_on_discarded_at"
+    t.index ["source_pattern"], name: "index_post_url_sanitisation_rules_on_source_pattern", unique: true
+  end
+
   create_table "post_versions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "post_id", null: false
     t.integer "version_no", null: false
@@ -243,9 +354,12 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
     t.datetime "original_created_before"
     t.datetime "created_at", null: false
     t.bigint "created_by_user_id"
+    t.integer "video_ms"
     t.index ["created_by_user_id"], name: "index_post_versions_on_created_by_user_id"
     t.index ["post_id", "version_no"], name: "index_post_versions_on_post_id_and_version_no", unique: true
     t.index ["post_id"], name: "index_post_versions_on_post_id"
+    t.index ["video_ms", "post_id"], name: "idx_post_versions_video_ms_post_id"
+    t.check_constraint "(`video_ms` is null) or (`video_ms` > 0)", name: "chk_post_versions_video_ms_positive"
     t.check_constraint "`event_type` in (_utf8mb4'create',_utf8mb4'update',_utf8mb4'discard',_utf8mb4'restore')", name: "post_versions_event_type_valid"
     t.check_constraint "`version_no` > 0", name: "post_versions_version_no_positive"
   end
@@ -260,18 +374,36 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
     t.datetime "original_created_before"
     t.datetime "updated_at", null: false
     t.integer "version_no", null: false
+    t.integer "video_ms"
     t.index ["uploaded_user_id"], name: "index_posts_on_uploaded_user_id"
     t.index ["url"], name: "index_posts_on_url", unique: true
+    t.index ["video_ms", "id"], name: "idx_posts_video_ms_id"
+    t.check_constraint "(`video_ms` is null) or (`video_ms` > 0)", name: "chk_posts_video_ms_positive"
     t.check_constraint "`version_no` > 0", name: "chk_posts_version_no_positive"
   end
 
   create_table "settings", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "user_id", null: false
-    t.string "key", null: false
-    t.json "value", null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
-    t.index ["user_id"], name: "index_settings_on_user_id"
+    t.string "theme", default: "system", null: false
+    t.string "auto_fetch_title", default: "manual", null: false
+    t.string "auto_fetch_thumbnail", default: "manual", null: false
+    t.string "wiki_editor_mode", default: "split", null: false
+    t.index ["user_id"], name: "index_settings_on_user_id", unique: true
+  end
+
+  create_table "wiki_assets", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "wiki_page_id", null: false
+    t.integer "no", null: false
+    t.string "alt_text"
+    t.binary "sha256", limit: 32, null: false
+    t.bigint "created_by_user_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["created_by_user_id"], name: "index_wiki_assets_on_created_by_user_id"
+    t.index ["wiki_page_id", "no"], name: "index_wiki_assets_on_wiki_page_id_and_no", unique: true
+    t.index ["wiki_page_id", "sha256"], name: "index_wiki_assets_on_wiki_page_id_and_sha256", unique: true
   end
 
   create_table "tag_implications", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
@@ -321,6 +453,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
     t.string "category", null: false
     t.text "aliases", null: false
     t.text "parent_tag_ids", null: false
+    t.datetime "deprecated_at"
     t.datetime "created_at", null: false
     t.bigint "created_by_user_id"
     t.index ["created_at"], name: "index_tag_versions_on_created_at"
@@ -333,13 +466,16 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
   create_table "tags", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "tag_name_id", null: false
     t.string "category", default: "general", null: false
+    t.datetime "deprecated_at"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.integer "post_count", default: 0, null: false
     t.datetime "discarded_at"
     t.integer "version_no", null: false
+    t.index ["deprecated_at"], name: "index_tags_on_deprecated_at"
     t.index ["discarded_at"], name: "index_tags_on_discarded_at"
     t.index ["tag_name_id"], name: "index_tags_on_tag_name_id", unique: true
+    t.check_constraint "(`deprecated_at` is null) or (`category` <> _utf8mb4'nico')", name: "chk_tags_deprecated_at_not_nico"
     t.check_constraint "`version_no` > 0", name: "chk_tags_version_no_positive"
   end
 
@@ -455,6 +591,19 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
     t.index ["post_id"], name: "index_user_post_views_on_post_id"
   end
 
+  create_table "user_theme_slots", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "user_id", null: false
+    t.string "base_theme", null: false
+    t.integer "slot_no", null: false
+    t.json "tokens", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["user_id", "base_theme", "slot_no"], name: "index_user_theme_slots_on_user_theme_and_slot", unique: true
+    t.index ["user_id"], name: "index_user_theme_slots_on_user_id"
+    t.check_constraint "`base_theme` in (_utf8mb4'light',_utf8mb4'dark')", name: "user_theme_slots_base_theme_valid"
+    t.check_constraint "`slot_no` between 1 and 3", name: "user_theme_slots_slot_no_valid"
+  end
+
   create_table "users", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "name"
     t.string "inheritance_code", limit: 64, null: false
@@ -465,19 +614,6 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
     t.index ["banned_at"], name: "index_users_on_banned_at"
   end
 
-  create_table "wiki_assets", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.bigint "wiki_page_id", null: false
-    t.integer "no", null: false
-    t.string "alt_text"
-    t.binary "sha256", limit: 32, null: false
-    t.bigint "created_by_user_id", null: false
-    t.datetime "created_at", null: false
-    t.datetime "updated_at", null: false
-    t.index ["created_by_user_id"], name: "index_wiki_assets_on_created_by_user_id"
-    t.index ["wiki_page_id", "no"], name: "index_wiki_assets_on_wiki_page_id_and_no", unique: true
-    t.index ["wiki_page_id", "sha256"], name: "index_wiki_assets_on_wiki_page_id_and_sha256", unique: true
-  end
-
   create_table "wiki_lines", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "sha256", limit: 64, null: false
     t.text "body", null: false
@@ -563,6 +699,12 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
   add_foreign_key "gekanator_question_suggestions", "users"
   add_foreign_key "gekanator_questions", "gekanator_question_suggestions"
   add_foreign_key "gekanator_questions", "users", column: "created_by_id"
+  add_foreign_key "material_export_items", "materials"
+  add_foreign_key "material_export_items", "users", column: "created_by_user_id"
+  add_foreign_key "material_import_blocks", "users", column: "created_by_user_id"
+  add_foreign_key "material_sync_sources", "users", column: "created_by_user_id"
+  add_foreign_key "material_sync_sources", "users", column: "updated_by_user_id"
+  add_foreign_key "material_sync_suppressions", "users", column: "created_by_user_id"
   add_foreign_key "material_versions", "materials"
   add_foreign_key "material_versions", "materials", column: "parent_id"
   add_foreign_key "material_versions", "tags"
@@ -580,6 +722,8 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
   add_foreign_key "post_implications", "posts", column: "parent_post_id"
   add_foreign_key "post_similarities", "posts"
   add_foreign_key "post_similarities", "posts", column: "target_post_id"
+  add_foreign_key "post_tag_sections", "posts"
+  add_foreign_key "post_tag_sections", "tags"
   add_foreign_key "post_tags", "posts"
   add_foreign_key "post_tags", "tags"
   add_foreign_key "post_tags", "users", column: "created_user_id"
@@ -619,6 +763,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
   add_foreign_key "user_ips", "users"
   add_foreign_key "user_post_views", "posts"
   add_foreign_key "user_post_views", "users"
+  add_foreign_key "user_theme_slots", "users"
   add_foreign_key "wiki_assets", "users", column: "created_by_user_id"
   add_foreign_key "wiki_assets", "wiki_pages"
   add_foreign_key "wiki_pages", "tag_names"

backend/db/seeds.rb

@@ -7,3 +7,21 @@
 #   ["Action", "Comedy", "Drama", "Horror"].each do |genre_name|
 #     MovieGenre.find_or_create_by!(name: genre_name)
 #   end
+
+material_sync_source_uri = ENV['MATERIAL_SYNC_SOURCE_URI']
+material_sync_source_file_id = ENV['MATERIAL_SYNC_SOURCE_FILE_ID']
+
+if material_sync_source_uri.present? || material_sync_source_file_id.present?
+  source = MaterialSyncSource.find_or_initialize_by(
+      name: ENV.fetch('MATERIAL_SYNC_SOURCE_NAME', 'Legacy URI material sync'))
+  source.assign_attributes(
+      source_kind: ENV.fetch('MATERIAL_SYNC_SOURCE_KIND', 'uri'),
+      source_uri: material_sync_source_uri,
+      source_path: ENV['MATERIAL_SYNC_SOURCE_PATH'],
+      source_file_id: material_sync_source_file_id,
+      profile: ENV.fetch('MATERIAL_SYNC_SOURCE_PROFILE', 'legacy_drive'),
+      enabled: ENV.fetch('MATERIAL_SYNC_SOURCE_ENABLED', 'true') != 'false',
+      default_tag_name: ENV['MATERIAL_SYNC_SOURCE_TAG_NAME'],
+      export_path_prefix: ENV['MATERIAL_SYNC_EXPORT_PATH_PREFIX'])
+  source.save!
+end

backend/lib/package.json

@@ -1,15 +0,0 @@
-{
-  "name": "lib",
-  "version": "1.0.0",
-  "main": "screenshot.js",
-  "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
-  },
-  "keywords": [],
-  "author": "",
-  "license": "ISC",
-  "description": "",
-  "dependencies": {
-    "puppeteer": "^24.10.0"
-  }
-}

backend/lib/screenshot.js

@@ -1,18 +0,0 @@
-const puppeteer = require ('puppeteer')
-const fs = require ('fs')
-
-
-void (async () => {
-  const url = process.argv[2]
-  const output = process.argv[3]
-
-  const browser = await puppeteer.launch ({
-      args: ['--no-sandbox', '--disable-setuid-sandbox'] })
-
-  const page = await browser.newPage ()
-  await page.setViewport ({ width: 960, height: 960 })
-  await page.goto (url, { waitUntil: 'networkidle2', timeout: 15000 })
-
-  await page.screenshot ({ path: output })
-  await browser.close ()
-}) ()

backend/lib/tasks/calc_post_similarities.rake

@@ -1,6 +1,6 @@
 namespace :post_similarity do
   desc '関聯投稿テーブル作成'
   task calc: :environment do
-    Similarity::Calc.call(Post, :tags)
+    Similarity::Calc.call(Post, :active_tags)
   end
 end

backend/lib/tasks/calc_tag_similarities.rake

@@ -1,6 +1,6 @@
 namespace :tag_similarity do
   desc '関聯タグ・テーブル作成'
   task calc: :environment do
-    Similarity::Calc.call(Tag, :posts)
+    Similarity::Calc.call(Tag, :posts, scope: Tag.where(deprecated_at: nil))
   end
 end

backend/lib/tasks/sync_materials.rake

@@ -0,0 +1,51 @@
+namespace :materials do
+  desc '素材同期'
+  task sync: :environment do
+    result = MaterialSyncRunner.sync_enabled!
+    message = [
+      "materials:sync imported=#{ result.imported }",
+      "updated=#{ result.updated }",
+      "unchanged=#{ result.unchanged }",
+      "suppressed=#{ result.suppressed }",
+      "failed=#{ result.failed }"
+    ].join(' ')
+
+    Rails.logger.info(message)
+    puts message
+
+    result.errors.each do |error|
+      Rails.logger.warn(error.to_json)
+      warn error.to_json
+    end
+  end
+
+  namespace :thumbnails do
+    desc '素材サムネールを補完'
+    task backfill: :environment do
+      counts = Hash.new(0)
+
+      Material
+        .with_attached_file
+        .with_attached_thumbnail
+        .find_each do |material|
+          next unless material.file.attached?
+          next if material.thumbnail.attached?
+
+          result = MaterialThumbnailGenerator.generate!(material)
+          counts[result] += 1
+        end
+
+      message =
+          "materials:thumbnails:backfill " \
+          "attached=#{ counts[:attached] } " \
+          "no_file=#{ counts[:no_file] } " \
+          "unsupported_content_type=#{ counts[:unsupported_content_type] } " \
+          "generation_failed=#{ counts[:generation_failed] } " \
+          "attach_failed=#{ counts[:attach_failed] } " \
+          "file_not_found=#{ counts[:file_not_found] } " \
+          "mini_magick_error=#{ counts[:mini_magick_error] }"
+      Rails.logger.info(message)
+      puts message
+    end
+  end
+end

backend/spec/factories/post_tag_sections.rb

@@ -0,0 +1,8 @@
+FactoryBot.define do
+  factory :post_tag_section do
+    association :post
+    association :tag
+    begin_ms { 1_000 }
+    end_ms { 2_000 }
+  end
+end

backend/spec/factories/post_tags.rb

@@ -0,0 +1,6 @@
+FactoryBot.define do
+  factory :post_tag do
+    association :post
+    association :tag
+  end
+end

backend/spec/factories/posts.rb

@@ -0,0 +1,8 @@
+FactoryBot.define do
+  factory :post do
+    sequence(:url) { |n| "https://example.com/factory-post-#{ n }" }
+    title { 'factory post' }
+    thumbnail_base { nil }
+    uploaded_user { nil }
+  end
+end

backend/spec/models/material_export_item_spec.rb

@@ -0,0 +1,57 @@
+require 'rails_helper'
+
+RSpec.describe MaterialExportItem, type: :model do
+  let(:user) { create(:user, :member) }
+  let(:tag) { Tag.create!(tag_name: TagName.create!(name: 'export_item'), category: :material) }
+  let(:material) do
+    Material.create!(tag:, url: 'https://example.com/material',
+                     created_by_user: user, updated_by_user: user)
+  end
+
+  it 'rejects blank export_path' do
+    item = described_class.new(material:, profile: 'legacy_drive', export_path: '')
+
+    expect(item).not_to be_valid
+    expect(item.errors[:export_path]).to be_present
+  end
+
+  it 'rejects absolute export_path' do
+    item = described_class.new(material:, profile: 'legacy_drive',
+                               export_path: '/素材/a.png')
+
+    expect(item).not_to be_valid
+    expect(item.errors[:export_path]).to be_present
+  end
+
+  it 'rejects parent traversal export_path' do
+    item = described_class.new(material:, profile: 'legacy_drive',
+                               export_path: '素材/../a.png')
+
+    expect(item).not_to be_valid
+    expect(item.errors[:export_path]).to be_present
+  end
+
+  it 'rejects double slash export_path' do
+    item = described_class.new(material:, profile: 'legacy_drive',
+                               export_path: '素材//a.png')
+
+    expect(item).not_to be_valid
+    expect(item.errors[:export_path]).to be_present
+  end
+
+  it 'rejects dot segment export_path' do
+    item = described_class.new(material:, profile: 'legacy_drive',
+                               export_path: './素材/a.png')
+
+    expect(item).not_to be_valid
+    expect(item.errors[:export_path]).to be_present
+  end
+
+  it 'rejects trailing slash export_path' do
+    item = described_class.new(material:, profile: 'legacy_drive',
+                               export_path: '素材/a/')
+
+    expect(item).not_to be_valid
+    expect(item.errors[:export_path]).to be_present
+  end
+end

backend/spec/models/material_spec.rb

@@ -0,0 +1,19 @@
+require 'rails_helper'
+
+RSpec.describe Material, type: :model do
+  let(:user) { create(:user, :member) }
+
+  it 'allows only material source kinds, not suppression prefix kinds' do
+    material = described_class.new(url: 'https://example.com/material',
+                                   source_kind: 'google_drive_path_prefix',
+                                   source_path: '素材/危険',
+                                   created_by_user: user,
+                                   updated_by_user: user)
+
+    expect(material).not_to be_valid
+    expect(material.errors[:source_kind]).to be_present
+
+    material.source_kind = 'google_drive_path'
+    expect(material).to be_valid
+  end
+end

backend/spec/models/post_tag_spec.rb

@@ -0,0 +1,41 @@
+RSpec.describe PostTag, type: :model do
+  describe '#sections' do
+    it 'loads sections by post_id and tag_id' do
+      post_tag = create(:post_tag)
+      section = create(:post_tag_section,
+                       post: post_tag.post,
+                       tag: post_tag.tag,
+                       begin_ms: 1000,
+                       end_ms: 2000)
+
+      expect(post_tag.sections).to contain_exactly(section)
+    end
+
+    it 'does not load sections for another tag on the same post' do
+      post = create(:post)
+      tag = create(:tag)
+      other_tag = create(:tag)
+
+      post_tag = create(:post_tag, post:, tag:)
+      create(:post_tag_section,
+             post:,
+             tag: other_tag,
+             begin_ms: 1000,
+             end_ms: 2000)
+
+      expect(post_tag.sections).to be_empty
+    end
+
+    it 'allows open-ended sections' do
+      post_tag = create(:post_tag)
+      section = create(:post_tag_section,
+                       post: post_tag.post,
+                       tag: post_tag.tag,
+                       begin_ms: 1000,
+                       end_ms: nil)
+
+      expect(section).to be_valid
+      expect(post_tag.sections).to contain_exactly(section)
+    end
+  end
+end

backend/spec/models/setting_spec.rb

@@ -0,0 +1,34 @@
+require 'rails_helper'
+
+RSpec.describe Setting, type: :model do
+  it 'accepts the default typed user settings' do
+    setting = described_class.new({ user: create(:user) }.merge(described_class.defaults))
+
+    expect(setting).to be_valid
+  end
+
+  it 'requires one settings row per user' do
+    user = create(:user)
+    described_class.create!({ user: }.merge(described_class.defaults))
+
+    duplicate = described_class.new({ user: }.merge(described_class.defaults))
+
+    expect(duplicate).not_to be_valid
+    expect(duplicate.errors[:user_id]).to be_present
+  end
+
+  it 'validates enum-like settings columns' do
+    setting = described_class.new(
+        { user: create(:user),
+          theme: 'neon',
+          auto_fetch_title: 'sometimes',
+          auto_fetch_thumbnail: 'sometimes',
+          wiki_editor_mode: 'sideways' })
+
+    expect(setting).not_to be_valid
+    expect(setting.errors[:theme]).to be_present
+    expect(setting.errors[:auto_fetch_title]).to be_present
+    expect(setting.errors[:auto_fetch_thumbnail]).to be_present
+    expect(setting.errors[:wiki_editor_mode]).to be_present
+  end
+end

backend/spec/models/tag_implication_spec.rb

@@ -0,0 +1,36 @@
+require 'rails_helper'
+
+RSpec.describe TagImplication, type: :model do
+  it 'rejects a parent tag that would create a cycle' do
+    child = create(:tag, name: 'tag_implication_cycle_child')
+    parent = create(:tag, name: 'tag_implication_cycle_parent')
+
+    described_class.create!(tag: child, parent_tag: parent)
+
+    implication = described_class.new(tag: parent, parent_tag: child)
+
+    expect(implication).not_to be_valid
+    expect(implication.errors[:parent_tag_id]).to include(
+      '親タグに子孫タグを指定すると循環します．'
+    )
+    expect(implication.errors[:base]).to be_present
+  end
+
+  it 'terminates even when existing data already contains a cycle' do
+    child = create(:tag, name: 'tag_implication_existing_cycle_child')
+    parent = create(:tag, name: 'tag_implication_existing_cycle_parent')
+    ancestor = create(:tag, name: 'tag_implication_existing_cycle_ancestor')
+
+    described_class.create!(tag: parent, parent_tag: ancestor)
+    described_class.insert_all!(
+      [
+        { tag_id: ancestor.id, parent_tag_id: parent.id,
+          created_at: Time.current, updated_at: Time.current }
+      ]
+    )
+
+    implication = described_class.new(tag: child, parent_tag: parent)
+
+    expect(implication).to be_valid
+  end
+end

backend/spec/models/tag_spec.rb

@@ -1,6 +1,178 @@
 require 'rails_helper'
 
 RSpec.describe Tag, type: :model do
+  describe '.normalise_tags!' do
+    it 'rejects deprecated tags when deny_deprecated is enabled' do
+      tag_name = TagName.create!(name: 'normalise deprecated tag')
+      deprecated_tag = Tag.create!(
+        tag_name:,
+        category: :general,
+        deprecated_at: 1.day.from_now
+      )
+
+      expect {
+        described_class.normalise_tags!(
+          [deprecated_tag.name],
+          deny_deprecated: true
+        )
+      }.to raise_error(Tag::DeprecatedTagNormalisationError) { |error|
+        expect(error.tag_names).to eq([deprecated_tag.name])
+      }
+    end
+
+    it 'rejects invalid section literals instead of treating them as zero' do
+      expect {
+        described_class.normalise_tags!(
+          ['normalise_invalid_section[1:aa-2:00]'],
+          with_sections: true
+        )
+      }.to raise_error(Tag::SectionLiteralParseError)
+    end
+
+    it 'parses open-ended section literals' do
+      result = described_class.normalise_tags!(
+        ['伊地知ニジカ[1:00-]'],
+        with_sections: true
+      )
+
+      tag = result.fetch(:tags).find { _1.name == '伊地知ニジカ' }
+      expect(result.fetch(:sections).fetch(tag.id)).to eq([[60_000, nil]])
+    end
+
+    it 'parses omitted begin as zero' do
+      result = described_class.normalise_tags!(
+        ['伊地知ニジカ[-1:00]'],
+        with_sections: true
+      )
+
+      tag = result.fetch(:tags).find { _1.name == '伊地知ニジカ' }
+      expect(result.fetch(:sections).fetch(tag.id)).to eq([[0, 60_000]])
+    end
+
+    it 'treats fully open section literals as plain tags' do
+      result = described_class.normalise_tags!(
+        ['伊地知ニジカ[-]'],
+        with_sections: true
+      )
+
+      tag = result.fetch(:tags).find { _1.name == '伊地知ニジカ' }
+      expect(result.fetch(:sections)[tag.id]).to be_nil
+    end
+
+    it 'treats [0:00-] as a plain tag' do
+      result = described_class.normalise_tags!(
+        ['伊地知ニジカ[0:00-]'],
+        with_sections: true
+      )
+
+      tag = result.fetch(:tags).find { _1.name == '伊地知ニジカ' }
+      expect(result.fetch(:sections)[tag.id]).to be_nil
+    end
+
+    it 'expands zero-width sections to one millisecond' do
+      result = described_class.normalise_tags!(
+        ['伊地知ニジカ[1:00-1:00]'],
+        with_sections: true
+      )
+
+      tag = result.fetch(:tags).find { _1.name == '伊地知ニジカ' }
+      expect(result.fetch(:sections).fetch(tag.id)).to eq([[60_000, 60_001]])
+    end
+
+    it 'swaps reversed section boundaries' do
+      result = described_class.normalise_tags!(
+        ['伊地知ニジカ[2:00-1:00]'],
+        with_sections: true
+      )
+
+      tag = result.fetch(:tags).find { _1.name == '伊地知ニジカ' }
+      expect(result.fetch(:sections).fetch(tag.id)).to eq([[60_000, 120_000]])
+    end
+
+    it 'merges open-ended sections over later bounded sections' do
+      result = described_class.normalise_tags!(
+        ['伊地知ニジカ[1:00-][2:00-3:00]'],
+        with_sections: true
+      )
+
+      tag = result.fetch(:tags).find { _1.name == '伊地知ニジカ' }
+      expect(result.fetch(:sections).fetch(tag.id)).to eq([[60_000, nil]])
+    end
+
+    it 'merges adjacent bounded and open-ended sections' do
+      result = described_class.normalise_tags!(
+        ['伊地知ニジカ[1:00-3:00][3:00-]'],
+        with_sections: true
+      )
+
+      tag = result.fetch(:tags).find { _1.name == '伊地知ニジカ' }
+      expect(result.fetch(:sections).fetch(tag.id)).to eq([[60_000, nil]])
+    end
+  end
+
+  describe '.expand_parent_tags' do
+    it 'expands through multiple deprecated parents to an active ancestor' do
+      child = create(:tag, name: 'expand_child')
+      deprecated_parent = create(
+        :tag,
+        name: 'expand_deprecated_parent',
+        deprecated_at: Time.current
+      )
+      deprecated_grandparent = create(
+        :tag,
+        name: 'expand_deprecated_grandparent',
+        deprecated_at: Time.current
+      )
+      active_ancestor = create(:tag, name: 'expand_active_ancestor')
+      TagImplication.create!(tag: child, parent_tag: deprecated_parent)
+      TagImplication.create!(tag: deprecated_parent, parent_tag: deprecated_grandparent)
+      TagImplication.create!(tag: deprecated_grandparent, parent_tag: active_ancestor)
+
+      expanded = described_class.expand_parent_tags([child])
+
+      expect(expanded).to include(
+        child,
+        deprecated_parent,
+        deprecated_grandparent,
+        active_ancestor
+      )
+      expect(expanded.reject(&:deprecated?)).to contain_exactly(child, active_ancestor)
+    end
+
+    it 'terminates when implications contain a cycle' do
+      first = create(:tag, name: 'expand_cycle_first')
+      second = create(:tag, name: 'expand_cycle_second')
+      TagImplication.create!(tag: first, parent_tag: second)
+      now = Time.current
+      TagImplication.insert_all!(
+        [
+          {
+            tag_id: second.id,
+            parent_tag_id: first.id,
+            created_at: now,
+            updated_at: now
+          }
+        ]
+      )
+
+      expect(described_class.expand_parent_tags([first])).to contain_exactly(first, second)
+    end
+  end
+
+  describe 'deprecated validation' do
+    it 'rejects deprecated nico tags' do
+      tag = build(
+        :tag,
+        name: 'nico:deprecated_validation',
+        category: :nico,
+        deprecated_at: Time.current
+      )
+
+      expect(tag).not_to be_valid
+      expect(tag.errors[:deprecated_at]).to include('ニコタグは廃止できません．')
+    end
+  end
+
   describe '.merge_tags!' do
     let!(:target_tag) { create(:tag, category: :general) }
     let!(:source_tag) { create(:tag, category: :general) }

backend/spec/models/user_theme_slot_spec.rb

@@ -0,0 +1,40 @@
+require 'rails_helper'
+
+RSpec.describe UserThemeSlot, type: :model do
+  it 'accepts a theme slot for one user, base theme, and slot number' do
+    slot = described_class.new(user: create(:user),
+                               base_theme: 'light',
+                               slot_no: 1,
+                               tokens: { 'background' => '0 0% 100%' })
+
+    expect(slot).to be_valid
+  end
+
+  it 'requires unique slot numbers per user and base theme' do
+    user = create(:user)
+    described_class.create!(user:,
+                            base_theme: 'dark',
+                            slot_no: 2,
+                            tokens: { 'background' => '222.2 84% 4.9%' })
+
+    duplicate = described_class.new(user:,
+                                    base_theme: 'dark',
+                                    slot_no: 2,
+                                    tokens: { 'background' => '0 0% 100%' })
+
+    expect(duplicate).not_to be_valid
+    expect(duplicate.errors[:user_id]).to be_present
+  end
+
+  it 'validates base theme, slot number, and token object shape' do
+    slot = described_class.new(user: create(:user),
+                               base_theme: 'system',
+                               slot_no: 4,
+                               tokens: 'not-object')
+
+    expect(slot).not_to be_valid
+    expect(slot.errors[:base_theme]).to be_present
+    expect(slot.errors[:slot_no]).to be_present
+    expect(slot.errors[:tokens]).to be_present
+  end
+end

backend/spec/requests/gekanator_learning_spec.rb

@@ -897,6 +897,37 @@ RSpec.describe 'Gekanator learning API', type: :request do
   end
 
   describe 'GET /gekanator/questions' do
+    it 'omits questions for deprecated tags' do
+      active_tag = Tag.create!(name: 'active_question_tag', category: :general)
+      deprecated_tag = Tag.create!(
+        name: 'deprecated_question_tag',
+        category: :general,
+        deprecated_at: Time.current
+      )
+
+      [active_tag, deprecated_tag].each do |question_tag|
+        GekanatorQuestion.create!(
+          text: "#{ question_tag.name }?",
+          kind: 'tag',
+          source: 'admin_curated',
+          status: 'accepted',
+          priority_weight: 1.0,
+          condition: {
+            type: 'tag',
+            key: "#{ question_tag.category }:#{ question_tag.name }"
+          },
+          created_by: admin
+        )
+      end
+
+      get '/gekanator/questions'
+
+      expect(response).to have_http_status(:ok)
+      question_ids = json.fetch('questions').map { |question| question.fetch('id') }
+      expect(question_ids).to include('tag:general:active_question_tag')
+      expect(question_ids).not_to include('tag:general:deprecated_question_tag')
+    end
+
     it 'returns accepted questions only and includes example_answers for post_similarity questions' do
       sign_in_as admin
 

backend/spec/requests/gekanator_posts_spec.rb

@@ -0,0 +1,33 @@
+require 'rails_helper'
+
+
+RSpec.describe 'Gekanator posts API', type: :request do
+  describe 'GET /gekanator/posts' do
+    it 'omits deprecated tags and returns the stored similarity cosine' do
+      active_tag = Tag.create!(name: 'active tag', category: :general)
+      deprecated_tag = Tag.create!(
+        name: 'deprecated tag',
+        category: :general,
+        deprecated_at: Time.current
+      )
+      post_record = Post.create!(title: 'source', url: 'https://example.com/source')
+      target_post = Post.create!(title: 'target', url: 'https://example.com/target')
+
+      PostTag.create!(post: post_record, tag: active_tag)
+      PostTag.create!(post: post_record, tag: deprecated_tag)
+      PostTag.create!(post: target_post, tag: deprecated_tag)
+      PostSimilarity.create!(post: post_record, target_post:, cos: 0.375)
+
+      get '/gekanator/posts'
+
+      expect(response).to have_http_status(:ok)
+
+      post_json = json.fetch('posts').find { |post| post.fetch('id') == post_record.id }
+      expect(post_json.fetch('tags').map { |tag| tag.fetch('name') }).to eq(['active tag'])
+      expect(post_json.fetch('post_similarity_edges')).to contain_exactly(
+        'target_post_id' => target_post.id,
+        'cos' => 0.375
+      )
+    end
+  end
+end

backend/spec/requests/materials_spec.rb

@@ -1,7 +1,10 @@
 require 'rails_helper'
 
 RSpec.describe 'Materials API', type: :request do
+  include ActiveJob::TestHelper
+
   let!(:member_user) { create(:user, :member) }
+  let!(:admin_user)  { create(:user, :admin) }
   let!(:guest_user)  { create(:user) }
 
   def dummy_upload(filename: 'dummy.png', type: 'image/png', body: 'dummy')
@@ -13,22 +16,29 @@ RSpec.describe 'Materials API', type: :request do
   end
 
   def build_material(tag:, user:, parent: nil, file: dummy_upload, url: nil)
-    Material.new(tag:, parent:, url:, created_by_user: user, updated_by_user: user).tap do |material|
+    Material.new(tag:, parent:, url:,
+                 created_by_user: user,
+                 updated_by_user: user).tap do |material|
       material.file.attach(file) if file
       material.save!
     end
   end
 
   describe 'GET /materials' do
-    let!(:tag_a) { Tag.create!(tag_name: TagName.create!(name: 'material_index_a'), category: :material) }
-    let!(:tag_b) { Tag.create!(tag_name: TagName.create!(name: 'material_index_b'), category: :material) }
+    let!(:tag_a) do
+      Tag.create!(tag_name: TagName.create!(name: 'material_index_a'), category: :material)
+    end
+    let!(:tag_b) do
+      Tag.create!(tag_name: TagName.create!(name: 'material_index_b'), category: :material)
+    end
 
     let!(:material_a) do
       build_material(tag: tag_a, user: member_user, file: dummy_upload(filename: 'a.png'))
     end
 
     let!(:material_b) do
-      build_material(tag: tag_b, user: member_user, parent: material_a, file: dummy_upload(filename: 'b.png'))
+      build_material(tag: tag_b, user: member_user, parent: material_a,
+                     file: dummy_upload(filename: 'b.png'))
     end
 
     before do
@@ -54,27 +64,36 @@ RSpec.describe 'Materials API', type: :request do
         'name' => 'material_index_b',
         'category' => 'material'
       )
-      expect(row['created_by_user']).to include(
-        'id' => member_user.id,
-        'name' => member_user.name
-      )
       expect(row['content_type']).to eq('image/png')
+      expect(row['media_kind']).to eq('image')
     end
 
-    it 'filters materials by tag_id' do
-      get '/materials', params: { tag_id: material_a.tag_id }
+    it 'filters materials by q' do
+      get '/materials', params: { q: 'material_index_a' }
 
       expect(response).to have_http_status(:ok)
       expect(json['count']).to eq(1)
       expect(response_materials.map { |m| m['id'] }).to eq([material_a.id])
     end
 
-    it 'filters materials by parent_id' do
-      get '/materials', params: { parent_id: material_a.id }
+    it 'filters materials by tag_state' do
+      untagged =
+          build_material(tag: nil, user: member_user,
+                         file: dummy_upload(filename: 'untagged.png'))
+
+      get '/materials', params: { tag_state: 'untagged' }
 
       expect(response).to have_http_status(:ok)
       expect(json['count']).to eq(1)
-      expect(response_materials.map { |m| m['id'] }).to eq([material_b.id])
+      expect(response_materials.map { |m| m['id'] }).to eq([untagged.id])
+    end
+
+    it 'filters materials by media_kind' do
+      get '/materials', params: { media_kind: 'image' }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['count']).to eq(2)
+      expect(response_materials.map { |m| m['media_kind'] }).to all(eq('image'))
     end
 
     it 'paginates and keeps total count' do
@@ -94,10 +113,74 @@ RSpec.describe 'Materials API', type: :request do
       expect(response_materials.size).to eq(1)
       expect(response_materials.first['id']).to eq(material_b.id)
     end
+
+    it 'filters by descendant tags and returns stable parent tag groups' do
+      root =
+          Tag.create!(tag_name: TagName.create!(name: 'material_scope_root'),
+                      category: :material)
+      child_b =
+          Tag.create!(tag_name: TagName.create!(name: 'material_scope_b'),
+                      category: :material)
+      child_a =
+          Tag.create!(tag_name: TagName.create!(name: 'material_scope_a'),
+                      category: :material)
+      deprecated =
+          Tag.create!(tag_name: TagName.create!(name: 'material_scope_old'),
+                      category: :material,
+                      deprecated_at: Time.current)
+      grandchild =
+          Tag.create!(tag_name: TagName.create!(name: 'material_scope_grandchild'),
+                      category: :material)
+      root_material =
+          build_material(tag: root, user: member_user,
+                         file: dummy_upload(filename: 'root.png'))
+      child_a_material =
+          build_material(tag: child_a, user: member_user,
+                         file: dummy_upload(filename: 'child_a.png'))
+      grandchild_material =
+          build_material(tag: grandchild, user: member_user,
+                         file: dummy_upload(filename: 'grandchild.png'))
+
+      TagImplication.create!(parent_tag: root, tag: child_b)
+      TagImplication.create!(parent_tag: root, tag: child_a)
+      TagImplication.create!(parent_tag: child_b, tag: deprecated)
+      TagImplication.create!(parent_tag: deprecated, tag: grandchild)
+
+      get '/materials',
+          params: { tag_id: root.id, include_descendants: '1',
+                    group_by: 'parent_tag', sort: 'id', direction: 'asc' }
+
+      expect(response).to have_http_status(:ok)
+      expect(response_materials.map { |m| m['id'] })
+        .to include(root_material.id, child_a_material.id, grandchild_material.id)
+      expect(json['tag_scope']).to eq(
+        'tag' => {
+          'id' => root.id,
+          'name' => 'material_scope_root',
+          'category' => 'material'
+        },
+        'include_descendants' => true
+      )
+      expect(json['groups'].map { |group| group.dig('tag', 'name') })
+        .to eq(['material_scope_a', 'material_scope_b', 'material_scope_root'])
+      expect(json['groups'].find { |group| group.dig('tag', 'id') == child_b.id }
+        .fetch('material_ids')).to eq([grandchild_material.id])
+    end
+
+    it 'returns nil tag_scope when tag_id is unknown' do
+      get '/materials', params: { tag_id: 999_999, group_by: 'parent_tag' }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['tag_scope']).to be_nil
+      expect(json['groups']).to eq([])
+      expect(response_materials).to eq([])
+    end
   end
 
   describe 'GET /materials/:id' do
-    let!(:tag) { Tag.create!(tag_name: TagName.create!(name: 'material_show'), category: :material) }
+    let!(:tag) do
+      Tag.create!(tag_name: TagName.create!(name: 'material_show'), category: :material)
+    end
     let!(:material) do
       build_material(tag:, user: member_user, file: dummy_upload(filename: 'show.png'))
     end
@@ -138,9 +221,22 @@ RSpec.describe 'Materials API', type: :request do
       end
     end
 
-    context 'when logged in' do
+    context 'when logged in but not member' do
       before { sign_in_as(guest_user) }
 
+      it 'returns 403' do
+        post '/materials', params: {
+          tag: 'material_create_guest_forbidden',
+          file: dummy_upload
+        }
+
+        expect(response).to have_http_status(:forbidden)
+      end
+    end
+
+    context 'when member' do
+      before { sign_in_as(member_user) }
+
       it 'returns 422 when tag is blank' do
         post '/materials', params: { tag: '   ', file: dummy_upload }
 
@@ -162,24 +258,68 @@ RSpec.describe 'Materials API', type: :request do
         expect do
           post '/materials', params: {
             tag: 'material_create_new',
-            file: dummy_upload(filename: 'created.png')
+            file: dummy_upload(filename: 'created.png'),
+            export_paths: { legacy_drive: '伊地知ニジカ/created.png' }
           }
         end.to change(Material, :count).by(1)
           .and change(Tag, :count).by(1)
           .and change(TagName, :count).by(1)
+          .and change(MaterialVersion, :count).by(1)
 
         expect(response).to have_http_status(:created)
 
         material = Material.order(:id).last
         expect(material.tag.name).to eq('material_create_new')
         expect(material.tag.category).to eq('material')
-        expect(material.created_by_user).to eq(guest_user)
-        expect(material.updated_by_user).to eq(guest_user)
+        expect(material.created_by_user).to eq(member_user)
+        expect(material.updated_by_user).to eq(member_user)
         expect(material.file.attached?).to be(true)
+        expect(material.version_no).to eq(1)
+        expect(material.material_versions.first.event_type).to eq('create')
+        expect(material.material_export_items.first.export_path).to eq('伊地知ニジカ/created.png')
+        expect(material.material_versions.first.export_paths_json).to eq(
+          'legacy_drive' => '伊地知ニジカ/created.png'
+        )
 
         expect(json['id']).to eq(material.id)
         expect(json.dig('tag', 'name')).to eq('material_create_new')
         expect(json['content_type']).to eq('image/png')
+        expect(json.dig('export_paths', 'legacy_drive')).to eq('伊地知ニジカ/created.png')
+      end
+
+      it 'creates a create tag_version for a newly created material tag' do
+        expect do
+          post '/materials', params: {
+            tag: 'material_create_versioned_tag',
+            file: dummy_upload(filename: 'created.png')
+          }
+        end.to change(TagVersion, :count).by(1)
+
+        expect(response).to have_http_status(:created)
+
+        tag = Tag.joins(:tag_name).find_by!(tag_names: { name: 'material_create_versioned_tag' })
+        version = tag.tag_versions.order(:version_no).last
+
+        expect(version.event_type).to eq('create')
+        expect(version.name).to eq('material_create_versioned_tag')
+        expect(version.category).to eq('material')
+        expect(version.created_by_user).to eq(member_user)
+      end
+
+      it 'snapshots attached file metadata and sha256' do
+        post '/materials', params: {
+          tag: 'material_create_file_version',
+          file: dummy_upload(filename: 'created.png', body: 'sha-body')
+        }
+
+        expect(response).to have_http_status(:created)
+
+        version = Material.order(:id).last.material_versions.first
+        expect(version.file_blob_id).to be_present
+        expect(version.file_filename).to eq('created.png')
+        expect(version.file_content_type).to eq('image/png')
+        expect(version.file_byte_size).to eq('sha-body'.bytesize)
+        expect(version.file_sha256).to eq(Digest::SHA256.hexdigest('sha-body'))
       end
 
       it 'returns 422 when the existing tag is not material/character' do
@@ -219,11 +359,33 @@ RSpec.describe 'Materials API', type: :request do
         expect(response).to have_http_status(:created)
         expect(json['url']).to eq('https://example.com/material-source')
       end
+
+      it 'rejects sha256-blocked file upload' do
+        sha256 = Digest::SHA256.hexdigest('blocked-body')
+        MaterialImportBlock.create!(match_kind: 'sha256',
+                                    sha256:,
+                                    reason: 'copyright_high_risk',
+                                    created_by_user: admin_user)
+
+        expect do
+          post '/materials', params: {
+            tag: 'material_blocked_create',
+            file: dummy_upload(filename: 'blocked.png', body: 'blocked-body')
+          }
+        end.not_to change(Material, :count)
+
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json.fetch('errors')).to include(
+          'file' => ['抑止された素材です: copyright_high_risk']
+        )
+      end
     end
   end
 
   describe 'PUT /materials/:id' do
-    let!(:tag) { Tag.create!(tag_name: TagName.create!(name: 'material_update_old'), category: :material) }
+    let!(:tag) do
+      Tag.create!(tag_name: TagName.create!(name: 'material_update_old'), category: :material)
+    end
     let!(:material) do
       build_material(tag:, user: member_user, file: dummy_upload(filename: 'old.png'))
     end
@@ -277,25 +439,26 @@ RSpec.describe 'Materials API', type: :request do
             'tag' => ['タグは必須です．'])
       end
 
-      it 'returns 422 when both file and url are blank' do
+      it 'keeps the existing file when file and url are omitted' do
         put "/materials/#{ material.id }", params: {
           tag: 'material_update_no_payload'
         }
 
-        expect(response).to have_http_status(:unprocessable_entity)
-        expect(json.fetch('errors')).to include(
-            'file' => ['ファイルまたは URL は必須です．'],
-            'url' => ['ファイルまたは URL は必須です．'])
+        expect(response).to have_http_status(:ok)
+        expect(material.reload.file.attached?).to be(true)
       end
 
       it 'updates tag, url, file, and updated_by_user' do
         old_blob_id = material.file.blob.id
 
-        put "/materials/#{ material.id }", params: {
-          tag: 'material_update_new',
-          url: 'https://example.com/updated-source',
-          file: dummy_upload(filename: 'updated.jpg', type: 'image/jpeg')
-        }
+        expect do
+          put "/materials/#{ material.id }", params: {
+            tag: 'material_update_new',
+            url: 'https://example.com/updated-source',
+            file: dummy_upload(filename: 'updated.jpg', type: 'image/jpeg'),
+            export_paths: { legacy_drive: '伊地知ニジカ/updated.jpg' }
+          }
+        end.to change(MaterialVersion, :count).by(2)
 
         expect(response).to have_http_status(:ok)
 
@@ -306,8 +469,15 @@ RSpec.describe 'Materials API', type: :request do
         expect(material.updated_by_user).to eq(member_user)
         expect(material.file.attached?).to be(true)
         expect(material.file.blob.id).not_to eq(old_blob_id)
+        expect(ActiveStorage::Blob.where(id: old_blob_id).exists?).to be(true)
         expect(material.file.blob.filename.to_s).to eq('updated.jpg')
         expect(material.file.blob.content_type).to eq('image/jpeg')
+        expect(material.version_no).to eq(2)
+        expect(material.material_versions.order(:version_no).last.event_type).to eq('update')
+        expect(material.material_export_items.first.export_path).to eq('伊地知ニジカ/updated.jpg')
+        expect(material.material_versions.order(:version_no).last.export_paths_json).to eq(
+          'legacy_drive' => '伊地知ニジカ/updated.jpg'
+        )
 
         expect(json['id']).to eq(material.id)
         expect(json['file']).to be_present
@@ -315,7 +485,74 @@ RSpec.describe 'Materials API', type: :request do
         expect(json.dig('tag', 'name')).to eq('material_update_new')
       end
 
-      it 'purges the existing file when file is omitted and url is provided' do
+      it 'creates a create tag_version when update creates a new tag' do
+        expect do
+          put "/materials/#{ material.id }", params: {
+            tag: 'material_update_versioned_tag',
+            file: dummy_upload(filename: 'updated.png')
+          }
+        end.to change(Tag, :count).by(1)
+          .and change(TagName, :count).by(1)
+          .and change(TagVersion, :count).by(1)
+
+        expect(response).to have_http_status(:ok)
+
+        tag = Tag.joins(:tag_name).find_by!(tag_names: { name: 'material_update_versioned_tag' })
+        version = tag.tag_versions.order(:version_no).last
+
+        expect(version.event_type).to eq('create')
+        expect(version.name).to eq('material_update_versioned_tag')
+        expect(version.category).to eq('material')
+        expect(version.created_by_user).to eq(member_user)
+      end
+
+      it 'backfills a create tag_version for an existing material tag without history' do
+        existing_tag =
+            Tag.create!(tag_name: TagName.create!(name: 'material_update_existing_no_history'),
+                        category: :material)
+
+        expect(existing_tag.tag_versions).to be_empty
+
+        expect do
+          put "/materials/#{ material.id }", params: {
+            tag: 'material_update_existing_no_history',
+            file: dummy_upload(filename: 'updated.png')
+          }
+        end.to change(TagVersion, :count).by(1)
+
+        expect(response).to have_http_status(:ok)
+
+        version = existing_tag.reload.tag_versions.order(:version_no).last
+        expect(version.event_type).to eq('create')
+        expect(version.name).to eq('material_update_existing_no_history')
+        expect(version.category).to eq('material')
+        expect(version.created_by_user).to eq(member_user)
+      end
+
+      it 'backfills a create tag_version for an existing character tag without history' do
+        existing_tag =
+            Tag.create!(tag_name: TagName.create!(name: 'material_update_character_no_history'),
+                        category: :character)
+
+        expect(existing_tag.tag_versions).to be_empty
+
+        expect do
+          put "/materials/#{ material.id }", params: {
+            tag: 'material_update_character_no_history',
+            file: dummy_upload(filename: 'updated.png')
+          }
+        end.to change(TagVersion, :count).by(1)
+
+        expect(response).to have_http_status(:ok)
+
+        version = existing_tag.reload.tag_versions.order(:version_no).last
+        expect(version.event_type).to eq('create')
+        expect(version.name).to eq('material_update_character_no_history')
+        expect(version.category).to eq('character')
+        expect(version.created_by_user).to eq(member_user)
+      end
+
+      it 'detaches the existing file without purging blob when url replaces file' do
         old_blob_id = material.file.blob.id
 
         put "/materials/#{ material.id }", params: {
@@ -331,9 +568,7 @@ RSpec.describe 'Materials API', type: :request do
         expect(material.updated_by_user).to eq(member_user)
         expect(material.file.attached?).to be(false)
 
-        expect(
-          ActiveStorage::Blob.where(id: old_blob_id).exists?
-        ).to be(false)
+        expect(ActiveStorage::Blob.where(id: old_blob_id).exists?).to be(true)
 
         expect(json['id']).to eq(material.id)
         expect(json['file']).to be_nil
@@ -341,11 +576,208 @@ RSpec.describe 'Materials API', type: :request do
         expect(json.dig('tag', 'name')).to eq('material_update_remove_file')
         expect(json['url']).to eq('https://example.com/updated-source')
       end
+
+      it 'does not increase version for the same snapshot update' do
+        MaterialVersionRecorder.record!(material:, event_type: :create,
+                                        created_by_user: member_user)
+        TagVersioning.ensure_snapshot!(tag, created_by_user: member_user)
+
+        expect do
+          put "/materials/#{ material.id }", params: {
+            tag: 'material_update_old'
+          }
+        end.not_to change(MaterialVersion, :count)
+
+        expect(tag.reload.tag_versions.count).to eq(1)
+
+        expect(response).to have_http_status(:ok)
+        expect(material.reload.version_no).to eq(1)
+      end
+
+      it 'records update version when only export_path changes' do
+        MaterialVersionRecorder.record!(material:, event_type: :create,
+                                        created_by_user: member_user)
+
+        expect do
+          put "/materials/#{ material.id }", params: {
+            tag: 'material_update_old',
+            export_paths: { legacy_drive: '素材/only-path.png' }
+          }
+        end.to change(MaterialVersion, :count).by(1)
+
+        expect(response).to have_http_status(:ok)
+        expect(material.reload.material_export_items.first.export_path).to eq('素材/only-path.png')
+        expect(material.material_versions.order(:version_no).last.export_paths_json).to eq(
+          'legacy_drive' => '素材/only-path.png'
+        )
+      end
+
+      it 'removes export_path item when blank is submitted' do
+        MaterialExportItem.create!(material:, profile: 'legacy_drive',
+                                   export_path: '素材/remove.png',
+                                   created_by_user: member_user)
+        MaterialVersionRecorder.record!(material:, event_type: :create,
+                                        created_by_user: member_user)
+
+        expect do
+          put "/materials/#{ material.id }", params: {
+            tag: 'material_update_old',
+            export_paths: { legacy_drive: '' }
+          }
+        end.to change(MaterialExportItem, :count).by(-1)
+          .and change(MaterialVersion, :count).by(1)
+
+        expect(response).to have_http_status(:ok)
+        expect(material.reload.material_export_items).to be_empty
+        expect(material.material_versions.order(:version_no).last.export_paths_json).to eq({})
+      end
+
+      it 'rejects sha256-blocked replacement file' do
+        sha256 = Digest::SHA256.hexdigest('blocked-update')
+        MaterialImportBlock.create!(match_kind: 'sha256',
+                                    sha256:,
+                                    reason: 'source_owner_request',
+                                    created_by_user: admin_user)
+
+        put "/materials/#{ material.id }", params: {
+          tag: 'material_update_old',
+          file: dummy_upload(filename: 'blocked.png', body: 'blocked-update')
+        }
+
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(material.reload.file.blob.filename.to_s).to eq('old.png')
+      end
+    end
+  end
+
+  describe 'GET /materials/download.zip' do
+    let!(:tag_a) { Tag.create!(tag_name: TagName.create!(name: 'zip_a'), category: :material) }
+    let!(:tag_b) { Tag.create!(tag_name: TagName.create!(name: 'zip_b'), category: :material) }
+    let!(:material_a) do
+      build_material(tag: tag_a, user: member_user,
+                     file: dummy_upload(filename: 'a.png', body: 'zip-a'))
+    end
+    let!(:material_b) do
+      build_material(tag: tag_b, user: member_user,
+                     file: dummy_upload(filename: 'b.png', body: 'zip-b'))
+    end
+
+    before do
+      MaterialExportItem.create!(material: material_a, profile: 'legacy_drive',
+                                 export_path: '素材/a.png',
+                                 created_by_user: member_user)
+      MaterialExportItem.create!(material: material_b, profile: 'legacy_drive',
+                                 export_path: '素材/b.png',
+                                 created_by_user: member_user)
+    end
+
+    it 'uses material_export_items.export_path as ZIP entry paths' do
+      get '/materials/download.zip', params: { profile: 'legacy_drive' }
+
+      expect(response).to have_http_status(:ok)
+      expect(response.media_type).to eq('application/zip')
+      expect(response.body.b).to include('素材/a.png'.b)
+      expect(response.body.b).to include('素材/b.png'.b)
+    end
+
+    it 'filters by tag_id' do
+      get '/materials/download.zip', params: { profile: 'legacy_drive', tag_id: tag_a.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(response.body.b).to include('素材/a.png'.b)
+      expect(response.body.b).not_to include('素材/b.png'.b)
+    end
+
+    it 'does not include disabled export items' do
+      material_b.material_export_items.first.update!(enabled: false)
+
+      get '/materials/download.zip', params: { profile: 'legacy_drive' }
+
+      expect(response).to have_http_status(:ok)
+      expect(response.body.b).to include('素材/a.png'.b)
+      expect(response.body.b).not_to include('素材/b.png'.b)
+    end
+  end
+
+  describe 'GET /materials/versions' do
+    let!(:tag) do
+      Tag.create!(tag_name: TagName.create!(name: 'material_history'), category: :material)
+    end
+    let!(:material) do
+      build_material(tag:, user: member_user, file: dummy_upload(filename: 'history.png'))
+    end
+
+    it 'returns material versions in reverse chronological order' do
+      MaterialVersionRecorder.record!(material:, event_type: :create,
+                                      created_by_user: member_user)
+      material.update!(url: 'https://example.com/history')
+      MaterialVersionRecorder.record!(material:, event_type: :update,
+                                      created_by_user: admin_user)
+
+      get '/materials/versions', params: { material_id: material.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json['count']).to eq(2)
+      versions = json.fetch('versions')
+      expect(versions.map { |v| v['version_no'] }).to eq([2, 1])
+      expect(versions.first).to include(
+        'material_id' => material.id,
+        'event_type' => 'update',
+        'tag_name' => 'material_history',
+        'file_filename' => 'history.png',
+        'url' => 'https://example.com/history'
+      )
+      expect(versions.first['created_by_user']).to include('id' => admin_user.id)
+    end
+
+    it 'filters material versions by tag and event_type' do
+      MaterialVersionRecorder.record!(material:, event_type: :create,
+                                      created_by_user: member_user)
+
+      get '/materials/versions', params: {
+        tag: 'material_history',
+        event_type: 'create'
+      }
+
+      expect(response).to have_http_status(:ok)
+      expect(json.fetch('versions').map { |v| v['material_id'] }).to include(material.id)
+      expect(json.fetch('versions').map { |v| v['event_type'] }).to all(eq('create'))
+    end
+  end
+
+  describe 'material sync suppressions' do
+    it 'requires member permission for index' do
+      sign_out
+
+      get '/materials/suppressions'
+
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it 'creates source suppression as member' do
+      sign_in_as(member_user)
+
+      expect do
+        post '/materials/suppressions', params: {
+          source_kind: 'google_drive_path_prefix',
+          drive_path: '伊地知ニジカ/危険素材',
+          reason: 'copyright_high_risk'
+        }
+      end.to change(MaterialSyncSuppression, :count).by(1)
+
+      expect(response).to have_http_status(:created)
+      expect(json).to include(
+        'source_kind' => 'google_drive_path_prefix',
+        'drive_path' => '伊地知ニジカ/危険素材',
+        'normalized_source_key' => 'google_drive_path_prefix:伊地知ニジカ/危険素材'
+      )
     end
   end
 
   describe 'DELETE /materials/:id' do
-    let!(:tag) { Tag.create!(tag_name: TagName.create!(name: 'material_destroy'), category: :material) }
+    let!(:tag) do
+      Tag.create!(tag_name: TagName.create!(name: 'material_destroy'), category: :material)
+    end
     let!(:material) do
       build_material(tag:, user: member_user, file: dummy_upload(filename: 'destroy.png'))
     end

backend/spec/requests/posts_spec.rb

@@ -1,4 +1,5 @@
 require 'rails_helper'
+require 'base64'
 require 'set'
 
 include ActiveSupport::Testing::TimeHelpers
@@ -8,6 +9,11 @@ RSpec.describe 'Posts API', type: :request do
   # resized_thumbnail! が MiniMagick 依存でコケやすいので request spec ではスタブしとくのが無難。
   before do
     allow_any_instance_of(Post).to receive(:resized_thumbnail!).and_return(true)
+    allow(Post).to receive(:resized_thumbnail_attachment).and_return(
+      io: StringIO.new('dummy'),
+      filename: 'resized_thumbnail.jpg',
+      content_type: 'image/jpeg'
+    )
   end
 
   def create_nico_tag!(name)
@@ -19,6 +25,18 @@ RSpec.describe 'Posts API', type: :request do
     Rack::Test::UploadedFile.new(StringIO.new('dummy'), 'image/jpeg', original_filename: 'dummy.jpg')
   end
 
+  def real_thumbnail_upload
+    gif =
+        Base64.decode64(
+            'R0lGODdhAQABAIABAP///wAAACwAAAAAAQABAAACAkQBADs=')
+
+    Rack::Test::UploadedFile.new(
+      StringIO.new(gif),
+      'image/gif',
+      original_filename: 'thumbnail.gif'
+    )
+  end
+
   def post_write_params params = { }
     { parent_post_ids: '' }.merge(params)
   end
@@ -36,6 +54,7 @@ RSpec.describe 'Posts API', type: :request do
             title: post.title,
             url: post.url,
             thumbnail_base: post.thumbnail_base,
+            video_ms: post.video_ms,
             tags: post.snapshot_tag_names.join(' '),
             parent_post_ids: post.snapshot_parent_post_ids.join(' '),
             original_created_from: post.original_created_from,
@@ -127,6 +146,22 @@ RSpec.describe 'Posts API', type: :request do
       expect(all_tag_names).to include("spec_tag")
     end
 
+    it 'keeps children and sections keys in non-detail tag responses' do
+      PostTagSection.create!(post: hit_post, tag:, begin_ms: 1_000, end_ms: nil)
+
+      get '/posts'
+
+      expect(response).to have_http_status(:ok)
+
+      hit_json = json.fetch('posts').find { |post| post['id'] == hit_post.id }
+      tag_json = hit_json.fetch('tags').find { |item| item['name'] == 'spec_tag' }
+
+      expect(tag_json.fetch('children')).to eq([])
+      expect(tag_json.fetch('sections')).to eq([
+        { 'begin_ms' => 1_000, 'end_ms' => nil }
+      ])
+    end
+
     context "when q is provided" do
       it "filters posts by q (hit case)" do
         get "/posts", params: { tags: "spec_tag" }
@@ -517,6 +552,24 @@ RSpec.describe 'Posts API', type: :request do
         expect([true, false]).to include(json['viewed'])
       end
 
+      it 'omits deprecated tags' do
+        deprecated_tag = Tag.create!(
+          name: 'deprecated_post_tag',
+          category: :general,
+          deprecated_at: Time.current
+        )
+        PostTag.create!(post: post_record, tag: deprecated_tag)
+
+        request
+
+        expect(response).to have_http_status(:ok)
+        tag_names = json.fetch('tags').flat_map { |node|
+          [node.fetch('name')] + node.fetch('children').map { |child| child.fetch('name') }
+        }
+        expect(tag_names).to include('spec_tag')
+        expect(tag_names).not_to include('deprecated_post_tag')
+      end
+
       context 'when post has parent, child, and sibling posts' do
         let!(:parent_post) do
           create_parent_post!(
@@ -678,6 +731,66 @@ RSpec.describe 'Posts API', type: :request do
       expect(json['tags'][0]).to have_key('name')
     end
 
+    it '201 when posting manually with a thumbnail' do
+      sign_in_as(member)
+      allow(Post).to receive(:resized_thumbnail_attachment).and_call_original
+
+      post '/posts', params: post_write_params(
+        title: 'thumbnail post',
+        url: 'https://example.com/thumbnail-post',
+        tags: 'spec_tag',
+        thumbnail: real_thumbnail_upload
+      )
+
+      expect(response).to have_http_status(:created)
+      post_record = Post.find(json.fetch('id'))
+      expect(post_record.thumbnail).to be_attached
+      expect(post_record.thumbnail.blob.content_type).to eq('image/jpeg')
+      expect { post_record.thumbnail.download }.not_to raise_error
+    end
+
+    it 'resizes the thumbnail before the create transaction begins' do
+      sign_in_as(member)
+
+      open_transactions = []
+      baseline_open_transactions = Post.connection.open_transactions
+      allow(Post).to receive(:resized_thumbnail_attachment) do |_upload|
+        open_transactions << Post.connection.open_transactions
+        { io: StringIO.new('dummy'),
+          filename: 'resized_thumbnail.jpg',
+          content_type: 'image/jpeg' }
+      end
+
+      post '/posts', params: post_write_params(
+        title: 'transaction post',
+        url: 'https://example.com/transaction-post',
+        tags: 'spec_tag',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:created)
+      expect(open_transactions).to eq([baseline_open_transactions])
+    end
+
+    it 'returns 422 and does not create a post when thumbnail resize fails' do
+      sign_in_as(member)
+      allow(Post).to receive(:resized_thumbnail_attachment).and_raise(MiniMagick::Error)
+
+      expect {
+        post '/posts', params: post_write_params(
+          title: 'broken thumbnail post',
+          url: 'https://example.com/broken-thumbnail-post',
+          tags: 'spec_tag',
+          thumbnail: dummy_upload
+        )
+      }.not_to change(Post, :count)
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json.fetch('errors')).to include(
+        'thumbnail' => ['サムネイル画像の変換に失敗しました．']
+      )
+    end
+
     it '201 and creates post + tags when member and tags have aliases' do
       sign_in_as(member)
 
@@ -697,6 +810,250 @@ RSpec.describe 'Posts API', type: :request do
       expect(names).not_to include('manko')
     end
 
+    it 'rejects a deprecated tag specified directly' do
+      Tag.create!(
+        name: 'deprecated_direct_tag',
+        category: :general,
+        deprecated_at: Time.current
+      )
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'new post',
+        url: 'https://example.com/deprecated-direct-tag',
+        tags: 'deprecated_direct_tag',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json.fetch('errors')).to include(
+        'tags' => ['廃止済みタグは付与できません．']
+      )
+    end
+
+    it 'expands through multiple deprecated parent tags and saves active ancestors' do
+      child = Tag.create!(name: 'active_child', category: :general)
+      deprecated_parent = Tag.create!(
+        name: 'deprecated_parent',
+        category: :general,
+        deprecated_at: Time.current
+      )
+      deprecated_grandparent = Tag.create!(
+        name: 'deprecated_grandparent',
+        category: :general,
+        deprecated_at: Time.current
+      )
+      active_grandparent = Tag.create!(name: 'active_grandparent', category: :general)
+      TagImplication.create!(tag: child, parent_tag: deprecated_parent)
+      TagImplication.create!(tag: deprecated_parent, parent_tag: deprecated_grandparent)
+      TagImplication.create!(tag: deprecated_grandparent, parent_tag: active_grandparent)
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'expanded post',
+        url: 'https://example.com/expanded-deprecated-parent',
+        tags: 'active_child',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:created)
+      saved_names = Post.find(json.fetch('id')).tags.map(&:name)
+      expect(saved_names).to include('active_child', 'active_grandparent')
+      expect(saved_names).not_to include('deprecated_parent', 'deprecated_grandparent')
+    end
+
+    it 'returns validation error for an invalid section literal' do
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'invalid section literal',
+        url: 'https://example.com/invalid-section-literal',
+        tags: 'spec_tag[1:aa-2:00]',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json).to include(
+        'type' => 'validation_error',
+        'message' => '入力内容を確認してください．'
+      )
+      expect(json.fetch('errors')).to include(
+        'tags' => ['タグ区間の記法が不正です．']
+      )
+    end
+
+    it 'creates a video post with duration' do
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'video post',
+        url: 'https://example.com/video-post',
+        tags: '動画 spec_tag',
+        duration: '3:00.500',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:created)
+      expect(Post.find(json.fetch('id')).video_ms).to eq(180_500)
+      expect(json.fetch('video_ms')).to eq(180_500)
+    end
+
+    it 'creates a video post with number input duration seconds' do
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'video post seconds',
+        url: 'https://example.com/video-post-seconds',
+        tags: '動画 spec_tag',
+        duration: '180.5',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:created)
+      expect(Post.find(json.fetch('id')).video_ms).to eq(180_500)
+      expect(json.fetch('video_ms')).to eq(180_500)
+    end
+
+    it 'clears video_ms when the saved tags do not include 動画' do
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'non video post',
+        url: 'https://example.com/non-video-post',
+        tags: 'spec_tag',
+        duration: '3:00',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:created)
+      expect(Post.find(json.fetch('id')).video_ms).to be_nil
+    end
+
+    it 'returns validation error when a bounded section exceeds duration' do
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'too long section',
+        url: 'https://example.com/too-long-section',
+        tags: '動画 伊地知ニジカ[2:50-3:10]',
+        duration: '3:00',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json.fetch('errors')).to include(
+        'video_ms' => ['タグ区間の終端が動画時間を超えてゐます．']
+      )
+    end
+
+    it 'saves open-ended sections with end_ms NULL' do
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'open ended section literal',
+        url: 'https://example.com/open-ended-section-literal',
+        tags: '動画 伊地知ニジカ[1:00-]',
+        duration: '3:00',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:created)
+
+      created_post = Post.find(json.fetch('id'))
+      tag = Tag.joins(:tag_name).find_by!(tag_names: { name: '伊地知ニジカ' })
+      section = PostTagSection.find_by!(post: created_post, tag:)
+
+      expect(section.begin_ms).to eq(60_000)
+      expect(section.end_ms).to be_nil
+    end
+
+    it 'does not save sections for [-]' do
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'fully open section literal',
+        url: 'https://example.com/fully-open-section-literal',
+        tags: '伊地知ニジカ[-]',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:created)
+
+      created_post = Post.find(json.fetch('id'))
+      tag = Tag.joins(:tag_name).find_by!(tag_names: { name: '伊地知ニジカ' })
+      expect(PostTagSection.find_by(post: created_post, tag:)).to be_nil
+    end
+
+    it 'does not save sections for [0:00-]' do
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'zero open ended section literal',
+        url: 'https://example.com/zero-open-ended-section-literal',
+        tags: '伊地知ニジカ[0:00-]',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:created)
+
+      created_post = Post.find(json.fetch('id'))
+      tag = Tag.joins(:tag_name).find_by!(tag_names: { name: '伊地知ニジカ' })
+      expect(PostTagSection.find_by(post: created_post, tag:)).to be_nil
+    end
+
+    it 'returns end_ms null for open-ended sections in show response' do
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'show open ended section literal',
+        url: 'https://example.com/show-open-ended-section-literal',
+        tags: '動画 伊地知ニジカ[1:00-]',
+        duration: '3:00',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:created)
+
+      get "/posts/#{ json.fetch('id') }"
+
+      expect(response).to have_http_status(:ok)
+      tag_json = json.fetch('tags').find { |item| item['name'] == '伊地知ニジカ' }
+      expect(tag_json.fetch('sections')).to eq([
+        { 'begin_ms' => 60_000, 'end_ms' => nil }
+      ])
+    end
+
+    it 'allows open-ended sections when begin is within duration' do
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'valid open ended section literal',
+        url: 'https://example.com/valid-open-ended-section-literal',
+        tags: '動画 伊地知ニジカ[1:00-]',
+        duration: '3:00',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:created)
+    end
+
+    it 'rejects open-ended sections when begin equals duration' do
+      sign_in_as(member)
+
+      post '/posts', params: post_write_params(
+        title: 'invalid open ended section literal',
+        url: 'https://example.com/invalid-open-ended-section-literal',
+        tags: '動画 伊地知ニジカ[3:00-]',
+        duration: '3:00',
+        thumbnail: dummy_upload
+      )
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json.fetch('errors')).to include(
+        'video_ms' => ['タグ区間の開始が動画時間以上です．']
+      )
+    end
+
     context "when nico tag already exists in tags" do
       before do
         Tag.find_undiscard_or_create_by!(
@@ -930,6 +1287,26 @@ RSpec.describe 'Posts API', type: :request do
       expect(names).to include('spec_tag_2')
     end
 
+    it 'rejects a deprecated tag specified directly' do
+      Tag.create!(
+        name: 'deprecated_update_tag',
+        category: :general,
+        deprecated_at: Time.current
+      )
+      sign_in_as(member)
+
+      put "/posts/#{ post_record.id }", params: post_update_params(
+        post_record,
+        title: 'updated title',
+        tags: 'deprecated_update_tag'
+      )
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json.fetch('errors')).to include(
+        'tags' => ['廃止済みタグは付与できません．']
+      )
+    end
+
     context "when nico tag already exists in tags" do
       before do
         Tag.find_undiscard_or_create_by!(

backend/spec/requests/preview_spec.rb

@@ -1,28 +1,46 @@
-require "rails_helper"
+require 'rails_helper'
 
 
-RSpec.describe "Preview", type: :request do
-  describe "GET /preview/title" do
-    it "401 unless logged in" do
+RSpec.describe 'Preview', type: :request do
+  describe 'GET /preview/title' do
+    it '401 unless logged in' do
       sign_out
-      get "/preview/title", params: { url: "example.com" }
+      get '/preview/title', params: { url: 'example.com' }
       expect(response).to have_http_status(:unauthorized)
     end
 
-    it "400 when url blank" do
-      sign_in_as(create(:user))
-      get "/preview/title", params: { url: "" }
+    it '403 when logged in as guest' do
+      sign_in_as(create(:user, :guest))
+      get '/preview/title', params: { url: 'example.com' }
+      expect(response).to have_http_status(:forbidden)
+    end
+
+    it '400 when url blank' do
+      sign_in_as(create(:user, :member))
+      get '/preview/title', params: { url: '' }
       expect(response).to have_http_status(:bad_request)
     end
 
-    it "returns parsed title (stubbing URI.open)" do
-      sign_in_as(create(:user))
-      fake_html = "<html><head><title>  Hello  </title></head></html>"
-      allow(URI).to receive(:open).and_return(StringIO.new(fake_html))
+    it 'returns parsed title' do
+      sign_in_as(create(:user, :member))
+      allow(Preview::ThumbnailFetcher)
+          .to receive(:title)
+          .with('example.com')
+          .and_return('Hello')
 
-      get "/preview/title", params: { url: "example.com" }
+      get '/preview/title', params: { url: 'example.com' }
       expect(response).to have_http_status(:ok)
-      expect(json["title"]).to eq("Hello")
+      expect(json['title']).to eq('Hello')
+    end
+
+    it '413 when fetched response is too large' do
+      sign_in_as(create(:user, :member))
+      allow(Preview::ThumbnailFetcher)
+          .to receive(:title)
+          .and_raise(Preview::HttpFetcher::ResponseTooLarge, '外部データが大きすぎます．')
+
+      get '/preview/title', params: { url: 'example.com' }
+      expect(response).to have_http_status(:payload_too_large)
     end
   end
 end

backend/spec/requests/tag_children_spec.rb

@@ -56,6 +56,17 @@ RSpec.describe "TagChildren", type: :request do
 
         expect(response).to have_http_status(:no_content)
       end
+
+      it 'returns 422 and does not create relation when the new link makes a cycle' do
+        TagImplication.create!(tag: parent, parent_tag: child)
+
+        expect {
+          do_request
+        }.not_to change(TagImplication, :count)
+
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(TagImplication.where(tag: child, parent_tag: parent)).not_to exist
+      end
     end
 
     context "when Tag.find raises (invalid ids)" do

backend/spec/requests/tag_versions_spec.rb

@@ -21,6 +21,7 @@ RSpec.describe 'TagVersions API', type: :request do
     event_type:,
     name:,
     category:,
+    deprecated_at: nil,
     aliases: [],
     parent_tags: [],
     created_by_user:,
@@ -33,6 +34,7 @@ RSpec.describe 'TagVersions API', type: :request do
             event_type: event_type,
             name: name,
             category: category,
+            deprecated_at: deprecated_at,
             aliases: Array(aliases).join(' '),
             parent_tag_ids: Array(parent_tags).map(&:id).join(' '),
             created_by_user: created_by_user,
@@ -65,6 +67,7 @@ RSpec.describe 'TagVersions API', type: :request do
       event_type: 'update',
       name: 'new_tag_name',
       category: 'meme',
+      deprecated_at: t_v2,
       aliases: ['alias_shared', 'alias_new'],
       parent_tags: [parent_shared, parent_new],
       created_by_user: member,
@@ -133,6 +136,10 @@ RSpec.describe 'TagVersions API', type: :request do
         'current' => 'meme',
         'prev' => 'general'
       )
+      expect(latest.fetch('deprecated_at')).to eq(
+        'current' => t_v2.iso8601,
+        'prev' => nil
+      )
       expect(latest.fetch('aliases')).to include(
         { 'name' => 'alias_shared', 'type' => 'context' },
         { 'name' => 'alias_new', 'type' => 'added' },
@@ -178,6 +185,10 @@ RSpec.describe 'TagVersions API', type: :request do
         'current' => 'general',
         'prev' => nil
       )
+      expect(first.fetch('deprecated_at')).to eq(
+        'current' => nil,
+        'prev' => nil
+      )
       expect(first.fetch('aliases')).to include(
         { 'name' => 'alias_shared', 'type' => 'added' },
         { 'name' => 'alias_old', 'type' => 'added' }

backend/spec/requests/tag_wiki_history_integrity_spec.rb

@@ -89,6 +89,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
           category: 'general',
           aliases: '',
           parent_tags: '',
+          deprecated: '0',
         }
       }
           .to change(TagVersion, :count).by(2)
@@ -123,6 +124,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
           category: 'meme',
           aliases: '',
           parent_tags: '',
+          deprecated: '0',
         }
       }
           .to change(TagVersion, :count).by(2)
@@ -149,6 +151,7 @@ RSpec.describe 'Tag and wiki history integrity', type: :request do
           category: 'general',
           aliases: 'put_tag_alias_only_alias',
           parent_tags: '',
+          deprecated: '0',
         }
       }
           .to change(TagVersion, :count).by(2)

backend/spec/requests/tags_spec.rb

@@ -76,6 +76,27 @@ RSpec.describe 'Tags API', type: :request do
       expect(response_tags.first['id']).to eq(meme.id)
     end
 
+    it 'filters tags by deprecated state' do
+      deprecated_tag = Tag.create!(
+        name: 'deprecated_filter',
+        category: :general,
+        deprecated_at: 1.day.from_now
+      )
+      active_tag = Tag.create!(name: 'active_filter', category: :general)
+
+      get '/tags', params: { name: '_filter', deprecated: '1' }
+
+      expect(response).to have_http_status(:ok)
+      expect(response_names).to include(deprecated_tag.name)
+      expect(response_names).not_to include(active_tag.name)
+
+      get '/tags', params: { name: '_filter', deprecated: '0' }
+
+      expect(response).to have_http_status(:ok)
+      expect(response_names).to include(active_tag.name)
+      expect(response_names).not_to include(deprecated_tag.name)
+    end
+
     it 'filters tags by post_count range' do
       low = Tag.create!(tag_name: TagName.create!(name: 'pc_low'), category: :general)
       mid = Tag.create!(tag_name: TagName.create!(name: 'pc_mid'), category: :general)
@@ -301,6 +322,21 @@ RSpec.describe 'Tags API', type: :request do
       expect(t['matched_alias']).to eq('unko')
       expect(json.map { |x| x['name'] }).not_to include('unknown')
     end
+
+    it 'omits deprecated tags' do
+      deprecated_tag = Tag.create!(
+        name: 'spec_deprecated',
+        category: :general,
+        deprecated_at: Time.current
+      )
+      deprecated_tag.update_columns(post_count: 1)
+
+      get '/tags/autocomplete', params: { q: 'spec_', present: '0' }
+
+      expect(response).to have_http_status(:ok)
+      expect(json.map { |item| item.fetch('name') }).to include('spec_tag')
+      expect(json.map { |item| item.fetch('name') }).not_to include('spec_deprecated')
+    end
   end
 
   describe 'GET /tags/name/:name' do
@@ -437,6 +473,32 @@ RSpec.describe 'Tags API', type: :request do
         expect(versions.second.created_by_user_id).to eq(member_user.id)
       end
 
+      it 'updates deprecated state and records it in tag versions' do
+        expect {
+          patch "/tags/#{ tag.id }", params: { deprecated: '1' }
+        }.to change(TagVersion, :count).by(2)
+
+        expect(response).to have_http_status(:ok)
+        expect(tag.reload.deprecated_at).to be_present
+
+        versions = tag.tag_versions.order(:version_no)
+        expect(versions.first.deprecated_at).to be_nil
+        expect(versions.second.deprecated_at).to eq(tag.deprecated_at)
+        expect(json.fetch('deprecated_at')).to be_present
+      end
+
+      it 'rejects deprecating a nico tag' do
+        nico_tag = Tag.create!(name: 'nico:deprecated_update', category: :nico)
+
+        patch "/tags/#{ nico_tag.id }", params: { deprecated: '1' }
+
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(nico_tag.reload.deprecated_at).to be_nil
+        expect(json.fetch('errors')).to include(
+          'deprecated' => ['ニコタグは廃止できません．']
+        )
+      end
+
       it 'returns 422 when changing normal tag category to nico' do
         expect {
           patch "/tags/#{tag.id}", params: { category: 'nico' }
@@ -519,6 +581,58 @@ RSpec.describe 'Tags API', type: :request do
         expect(response).to have_http_status(:ok)
         expect(wiki_page.reload.wiki_versions.count).to eq(before_wiki_version_count)
       end
+
+      it 'full update で旧名 alias が残った tag を PATCH で旧名へ戻せる' do
+        put "/tags/#{ tag.id }", params: {
+          name: 'patch_roundtrip_target',
+          category: 'general',
+          aliases: 'unko',
+          parent_tags: '',
+          deprecated: '0',
+        }
+
+        expect(response).to have_http_status(:ok)
+        expect(TagName.find_by!(name: 'spec_tag').canonical).to eq(tag.reload.tag_name)
+
+        patch "/tags/#{ tag.id }", params: { name: 'spec_tag' }
+
+        expect(response).to have_http_status(:ok)
+
+        tag.reload
+
+        expect(tag.name).to eq('spec_tag')
+        expect(tag.tag_name.canonical_id).to be_nil
+        expect(TagName.find_by!(name: 'patch_roundtrip_target').canonical).to eq(tag.tag_name)
+      end
+
+      it '別 tag の正規名には変更できない' do
+        wiki_page =
+            Wiki::Commit.create_content!(
+                tag_name: tag.tag_name,
+                body: 'patch collision wiki',
+                created_by_user: member_user,
+                message: 'init')
+
+        patch "/tags/#{ tag.id }", params: { name: 'unknown' }
+
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json.fetch('errors')).to include(
+          'name' => ['その名前は既に使はれてゐます．']
+        )
+
+        expect(tag.reload.name).to eq('spec_tag')
+        expect(tag.tag_name.aliases.map(&:name)).to contain_exactly('unko')
+        expect(wiki_page.reload.tag_name).to eq(tag.tag_name)
+      end
+
+      it 'system tag の name は変更できない' do
+        system_tag = Tag.bot
+
+        patch "/tags/#{ system_tag.id }", params: { name: 'patch_system_tag_renamed' }
+
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(system_tag.reload.name).to eq('bot操作')
+      end
     end
   end
 
@@ -585,6 +699,121 @@ RSpec.describe 'Tags API', type: :request do
       expect(row['has_children']).to eq(true)
       expect(row['children']).to eq([])
     end
+
+    it 'passes through deprecated tags when finding children' do
+      deprecated_middle = Tag.create!(
+        name: 'depth_deprecated_middle',
+        category: :character,
+        deprecated_at: Time.current
+      )
+      visible_descendant = Tag.create!(
+        name: 'depth_visible_descendant',
+        category: :material
+      )
+      TagImplication.create!(parent_tag: root_material, tag: deprecated_middle)
+      TagImplication.create!(parent_tag: deprecated_middle, tag: visible_descendant)
+
+      get '/tags/with-depth', params: { parent: root_material.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json.map { |item| item.fetch('name') }).to eq(['depth_visible_descendant'])
+      expect(json.map { |item| item.fetch('name') }).not_to include('depth_deprecated_middle')
+    end
+
+    it 'passes through multiple deprecated tags for roots and has_children' do
+      active_child = Tag.create!(
+        name: 'depth_active_child_below_deprecated',
+        category: :character
+      )
+      deprecated_parent = Tag.create!(
+        name: 'depth_deprecated_parent',
+        category: :character,
+        deprecated_at: Time.current
+      )
+      deprecated_grandparent = Tag.create!(
+        name: 'depth_deprecated_grandparent',
+        category: :material,
+        deprecated_at: Time.current
+      )
+      active_ancestor = Tag.create!(
+        name: 'depth_active_ancestor',
+        category: :meme
+      )
+      TagImplication.create!(tag: active_child, parent_tag: deprecated_parent)
+      TagImplication.create!(tag: deprecated_parent, parent_tag: deprecated_grandparent)
+      TagImplication.create!(tag: deprecated_grandparent, parent_tag: active_ancestor)
+
+      get '/tags/with-depth'
+
+      root_names = json.map { |item| item.fetch('name') }
+      expect(root_names).to include('depth_active_ancestor')
+      expect(root_names).not_to include('depth_active_child_below_deprecated')
+      ancestor_json = json.find { |item| item.fetch('id') == active_ancestor.id }
+      expect(ancestor_json.fetch('has_children')).to eq(true)
+
+      get '/tags/with-depth', params: { parent: active_ancestor.id }
+
+      expect(json.map { |item| item.fetch('name') }).to include(
+        'depth_active_child_below_deprecated'
+      )
+      expect(json.map { |item| item.fetch('name') }).not_to include(
+        'depth_deprecated_parent',
+        'depth_deprecated_grandparent'
+      )
+    end
+
+    it 'treats an active tag with only deprecated ancestors as a root' do
+      active_child = Tag.create!(
+        name: 'depth_root_below_deprecated',
+        category: :character
+      )
+      deprecated_parent = Tag.create!(
+        name: 'depth_root_deprecated_parent',
+        category: :material,
+        deprecated_at: Time.current
+      )
+      TagImplication.create!(tag: active_child, parent_tag: deprecated_parent)
+
+      get '/tags/with-depth'
+
+      expect(json.map { |item| item.fetch('name') }).to include(
+        'depth_root_below_deprecated'
+      )
+      expect(json.map { |item| item.fetch('name') }).not_to include(
+        'depth_root_deprecated_parent'
+      )
+    end
+
+    it 'terminates when deprecated implications contain a cycle' do
+      first = Tag.create!(
+        name: 'depth_cycle_first',
+        category: :character,
+        deprecated_at: Time.current
+      )
+      second = Tag.create!(
+        name: 'depth_cycle_second',
+        category: :material,
+        deprecated_at: Time.current
+      )
+      TagImplication.create!(tag: first, parent_tag: root_material)
+      TagImplication.create!(tag: second, parent_tag: first)
+      now = Time.current
+      TagImplication.insert_all!(
+        [
+          {
+            tag_id: first.id,
+            parent_tag_id: second.id,
+            created_at: now,
+            updated_at: now
+          }
+        ]
+      )
+
+      get '/tags/with-depth', params: { parent: root_material.id }
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to eq([])
+    end
   end
 
   describe 'GET /tags/name/:name/materials' do
@@ -732,6 +961,20 @@ RSpec.describe 'Tags API', type: :request do
         expect(tag.category).to eq('general')
       end
 
+      it 'deprecated がなければ 422 を返す' do
+        put "/tags/#{ tag.id }", params: {
+          name: 'new',
+          category: 'general',
+          aliases: '',
+          parent_tags: '',
+        }
+
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json.fetch('errors')).to include(
+          'deprecated' => ['廃止状態は必須です．']
+        )
+      end
+
       it 'name, category, aliases, parent tags をまとめて更新できる' do
         old_parent = Tag.create!(
           tag_name: TagName.create!(name: 'put_old_parent'),
@@ -749,6 +992,7 @@ RSpec.describe 'Tags API', type: :request do
           category: 'meme',
           aliases: 'put_alias_a put_alias_b put_alias_a',
           parent_tags: 'put_kept_parent put_new_parent',
+          deprecated: '0',
         }
 
         expect(response).to have_http_status(:ok)
@@ -793,6 +1037,7 @@ RSpec.describe 'Tags API', type: :request do
           category: 'general',
           aliases: 'spec_tag put_alias_self_test',
           parent_tags: '',
+          deprecated: '0',
         }
 
         expect(response).to have_http_status(:ok)
@@ -810,6 +1055,7 @@ RSpec.describe 'Tags API', type: :request do
           category: 'general',
           aliases: 'unko',
           parent_tags: 'spec_tag',
+          deprecated: '0',
         }
 
         expect(response).to have_http_status(:ok)
@@ -825,6 +1071,7 @@ RSpec.describe 'Tags API', type: :request do
             category: 'meta',
             aliases: '',
             parent_tags: '',
+            deprecated: '0',
           }
         }.to change(TagVersion, :count).by(2)
 
@@ -844,6 +1091,42 @@ RSpec.describe 'Tags API', type: :request do
         expect(versions.second.created_by_user_id).to eq(member_user.id)
       end
 
+      it '同じ tag の旧 alias へ戻しても rename できる' do
+        put "/tags/#{ tag.id }", params: {
+          name: 'put_roundtrip_b',
+          category: 'general',
+          aliases: 'unko',
+          parent_tags: '',
+          deprecated: '0',
+        }
+
+        expect(response).to have_http_status(:ok)
+
+        put "/tags/#{ tag.id }", params: {
+          name: 'spec_tag',
+          category: 'general',
+          aliases: 'unko',
+          parent_tags: '',
+          deprecated: '0',
+        }
+
+        expect(response).to have_http_status(:ok)
+
+        tag.reload
+
+        expect(tag.name).to eq('spec_tag')
+        expect(TagName.find_by!(name: 'put_roundtrip_b').canonical).to eq(tag.tag_name)
+        expect(tag.tag_name.aliases.map(&:name)).to contain_exactly('put_roundtrip_b', 'unko')
+        expect(tag.tag_name.aliases.map(&:name)).not_to include('spec_tag')
+        expect(alias_tn.reload.canonical).to eq(tag.tag_name)
+
+        version = tag.tag_versions.order(:version_no).last
+
+        expect(version.event_type).to eq('update')
+        expect(version.name).to eq('spec_tag')
+        expect(version.aliases.split).to contain_exactly('put_roundtrip_b', 'unko')
+      end
+
       it 'parent tag の snapshot も作成する' do
         old_parent = Tag.create!(
           tag_name: TagName.create!(name: 'put_snapshot_old_parent'),
@@ -860,6 +1143,7 @@ RSpec.describe 'Tags API', type: :request do
           category: 'general',
           aliases: 'unko',
           parent_tags: new_parent.name,
+          deprecated: '0',
         }
 
         expect(response).to have_http_status(:ok)
@@ -875,6 +1159,7 @@ RSpec.describe 'Tags API', type: :request do
             category: 'nico',
             aliases: '',
             parent_tags: '',
+            deprecated: '0',
           }
         }.not_to change(TagVersion, :count)
 
@@ -896,6 +1181,7 @@ RSpec.describe 'Tags API', type: :request do
             category: 'nico',
             aliases: '',
             parent_tags: '',
+            deprecated: '0',
           }
         }.not_to change(NicoTagVersion, :count)
 
@@ -916,6 +1202,7 @@ RSpec.describe 'Tags API', type: :request do
             category: old_category,
             aliases: '',
             parent_tags: '',
+            deprecated: '0',
           }
         }.not_to change(TagVersion, :count)
 
@@ -946,6 +1233,7 @@ RSpec.describe 'Tags API', type: :request do
             category: 'meme',
             aliases: 'unko',
             parent_tags: '',
+            deprecated: '0',
           }
         }
             .to change(TagVersion, :count).by(2)
@@ -963,6 +1251,48 @@ RSpec.describe 'Tags API', type: :request do
         )
       end
 
+      it 'wiki を持つ tag を旧 alias へ戻しても wiki を新 canonical へ移す' do
+        wiki_page =
+            Wiki::Commit.create_content!(
+                tag_name: tag.tag_name,
+                body: 'wiki body before',
+                created_by_user: member_user,
+                message: 'init')
+
+        expect {
+          put "/tags/#{ tag.id }", params: {
+            name: 'put_wiki_roundtrip_b',
+            category: 'general',
+            aliases: 'unko',
+            parent_tags: '',
+            deprecated: '0',
+          }
+
+          put "/tags/#{ tag.id }", params: {
+            name: 'spec_tag',
+            category: 'general',
+            aliases: 'unko',
+            parent_tags: '',
+            deprecated: '0',
+          }
+        }
+            .to change(TagVersion, :count).by(3)
+            .and change(WikiVersion, :count).by(2)
+
+        expect(response).to have_http_status(:ok)
+
+        tag.reload
+
+        expect(wiki_page.reload.tag_name).to eq(tag.tag_name)
+        expect(TagName.find_by!(name: 'put_wiki_roundtrip_b').wiki_page).to be_nil
+        expect(TagName.find_by!(name: 'put_wiki_roundtrip_b').canonical).to eq(tag.tag_name)
+
+        versions = wiki_page.wiki_versions.order(:version_no).last(2)
+
+        expect(versions.map(&:event_type)).to eq(['update', 'update'])
+        expect(versions.map(&:title)).to eq(['put_wiki_roundtrip_b', 'spec_tag'])
+      end
+
       it '別名を他 tag から奪った場合、奪はれた側の tag version も作成する' do
         old_owner = Tag.create!(
           tag_name: TagName.create!(name: 'put_alias_old_owner'),
@@ -981,6 +1311,7 @@ RSpec.describe 'Tags API', type: :request do
             category: 'general',
             aliases: 'unko put_stolen_alias',
             parent_tags: '',
+            deprecated: '0',
           }
         }
             .to change { tag.reload.tag_versions.count }.by(2)
@@ -1000,9 +1331,49 @@ RSpec.describe 'Tags API', type: :request do
         expect(old_owner_versions.second.aliases.split).not_to include('put_stolen_alias')
       end
 
-      it 'parent_tags に指定すると循環する tag は 422 にする' do
-        pending '#332 で対応予定'
+      it '別 tag の alias 名を rename で奪へる' do
+        old_owner = Tag.create!(
+          tag_name: TagName.create!(name: 'put_alias_collision_owner'),
+          category: :general
+        )
+        stolen_alias = TagName.create!(
+          name: 'put_alias_collision_name',
+          canonical: old_owner.tag_name
+        )
+        wiki_page =
+            Wiki::Commit.create_content!(
+                tag_name: tag.tag_name,
+                body: 'put collision wiki',
+                created_by_user: member_user,
+                message: 'init')
 
+        put "/tags/#{ tag.id }", params: {
+          name: 'put_alias_collision_name',
+          category: 'general',
+          aliases: 'unko',
+          parent_tags: '',
+          deprecated: '0',
+        }
+
+        expect(response).to have_http_status(:ok)
+
+        tag.reload
+        old_owner.reload
+        stolen_alias.reload
+
+        expect(tag.name).to eq('put_alias_collision_name')
+        expect(stolen_alias.canonical_id).to be_nil
+        expect(TagName.find_by!(name: 'spec_tag').canonical).to eq(tag.tag_name)
+        expect(old_owner.tag_name.aliases.map(&:name)).not_to include('put_alias_collision_name')
+
+        old_owner_versions = old_owner.tag_versions.order(:version_no)
+
+        expect(old_owner_versions.last.event_type).to eq('update')
+        expect(old_owner_versions.last.aliases.split).not_to include('put_alias_collision_name')
+        expect(wiki_page.reload.tag_name).to eq(tag.tag_name)
+      end
+
+      it 'parent_tags に指定すると循環する tag は 422 にする' do
         child = Tag.create!(
           tag_name: TagName.create!(name: 'put_cycle_child'),
           category: :general
@@ -1015,6 +1386,7 @@ RSpec.describe 'Tags API', type: :request do
           category: 'general',
           aliases: 'unko',
           parent_tags: child.name,
+          deprecated: '0',
         }
 
         expect(response).to have_http_status(:unprocessable_entity)
@@ -1036,6 +1408,7 @@ RSpec.describe 'Tags API', type: :request do
             category: 'general',
             aliases: 'unko',
             parent_tags: '',
+            deprecated: '0',
           }
         }
             .to change(TagVersion, :count).by(2)

backend/spec/requests/user_settings_spec.rb

@@ -0,0 +1,98 @@
+require 'rails_helper'
+
+RSpec.describe 'user settings', type: :request do
+  describe 'GET /users/settings' do
+    it 'requires a current user' do
+      sign_out
+
+      get '/users/settings'
+
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it 'returns defaults and creates a missing settings row' do
+      user = create(:user)
+      sign_in_as(user)
+
+      expect {
+        get '/users/settings'
+      }.to change(Setting, :count).by(1)
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to eq(
+          'theme' => 'system',
+          'auto_fetch_title' => 'manual',
+          'auto_fetch_thumbnail' => 'manual',
+          'wiki_editor_mode' => 'split')
+      expect(user.reload.setting).to be_present
+    end
+  end
+
+  describe 'PATCH /users/settings' do
+    it 'requires a current user' do
+      sign_out
+
+      patch '/users/settings', params: { theme: 'dark' }, as: :json
+
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it 'updates multiple typed settings at once' do
+      user = create(:user)
+      sign_in_as(user)
+
+      patch '/users/settings',
+            params: {
+              theme: 'dark',
+              auto_fetch_title: 'auto',
+              auto_fetch_thumbnail: 'off',
+              wiki_editor_mode: 'preview' },
+            as: :json
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to include(
+          'theme' => 'dark',
+          'auto_fetch_title' => 'auto',
+          'auto_fetch_thumbnail' => 'off',
+          'wiki_editor_mode' => 'preview')
+      expect(user.reload.setting).to have_attributes(
+          theme: 'dark',
+          auto_fetch_title: 'auto',
+          auto_fetch_thumbnail: 'off',
+          wiki_editor_mode: 'preview')
+    end
+
+    it 'does not treat Rails parameter wrapping as an editable setting' do
+      user = create(:user)
+      sign_in_as(user)
+
+      patch '/users/settings',
+            params: { theme: 'light', user_setting: { theme: 'dark' } },
+            as: :json
+
+      expect(response).to have_http_status(:ok)
+      expect(user.reload.setting.theme).to eq('light')
+    end
+
+    it 'returns validation_error for type mismatches' do
+      sign_in_as(create(:user))
+
+      patch '/users/settings', params: { theme: 1 }, as: :json
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json).to include('type' => 'validation_error')
+      expect(json.fetch('errors')).to include(
+          'theme' => ['値の型が不正です．'])
+    end
+
+    it 'returns validation_error for invalid enum values' do
+      sign_in_as(create(:user))
+
+      patch '/users/settings', params: { theme: 'neon' }, as: :json
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json).to include('type' => 'validation_error')
+      expect(json.fetch('errors').fetch('theme')).to be_present
+    end
+  end
+end

backend/spec/requests/user_theme_slots_spec.rb

@@ -0,0 +1,104 @@
+require 'rails_helper'
+
+RSpec.describe 'user theme slots', type: :request do
+  describe 'GET /users/theme_slots' do
+    it 'requires a current user' do
+      sign_out
+
+      get '/users/theme_slots'
+
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it 'returns only the current user slots in stable order' do
+      user = create(:user)
+      other_user = create(:user)
+      sign_in_as(user)
+      UserThemeSlot.create!(user:, base_theme: 'light', slot_no: 2, tokens: { 'a' => 1 })
+      UserThemeSlot.create!(user:, base_theme: 'dark', slot_no: 1, tokens: { 'b' => 2 })
+      UserThemeSlot.create!(user: other_user,
+                            base_theme: 'dark',
+                            slot_no: 3,
+                            tokens: { 'c' => 3 })
+
+      get '/users/theme_slots'
+
+      expect(response).to have_http_status(:ok)
+      expect(json.map { |slot| [slot.fetch('base_theme'), slot.fetch('slot_no')] }).to eq(
+          [['dark', 1], ['light', 2]])
+      expect(json.map { |slot| slot.fetch('tokens') }).to eq(
+          [{ 'b' => 2 }, { 'a' => 1 }])
+    end
+  end
+
+  describe 'PUT /users/theme_slots/:base_theme/:slot_no' do
+    it 'requires a current user' do
+      sign_out
+
+      put '/users/theme_slots/light/1',
+          params: { tokens: { background: '0 0% 100%' } },
+          as: :json
+
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it 'creates a theme slot' do
+      user = create(:user)
+      sign_in_as(user)
+
+      expect {
+        put '/users/theme_slots/light/1',
+            params: { tokens: { background: '0 0% 100%', tagColours: { nico: '#ffffff' } } },
+            as: :json
+      }.to change(UserThemeSlot, :count).by(1)
+
+      expect(response).to have_http_status(:ok)
+      expect(json).to include('base_theme' => 'light', 'slot_no' => 1)
+      expect(json.fetch('tokens')).to include(
+          'background' => '0 0% 100%',
+          'tagColours' => { 'nico' => '#ffffff' })
+      expect(user.theme_slots.find_by!(base_theme: 'light', slot_no: 1).tokens).to include(
+          'background' => '0 0% 100%')
+    end
+
+    it 'updates an existing theme slot instead of creating a duplicate' do
+      user = create(:user)
+      sign_in_as(user)
+      UserThemeSlot.create!(user:, base_theme: 'dark', slot_no: 2, tokens: { 'old' => true })
+
+      expect {
+        put '/users/theme_slots/dark/2',
+            params: { tokens: { background: '222.2 84% 4.9%' } },
+            as: :json
+      }.not_to change(UserThemeSlot, :count)
+
+      expect(response).to have_http_status(:ok)
+      expect(user.theme_slots.find_by!(base_theme: 'dark', slot_no: 2).tokens).to eq(
+          'background' => '222.2 84% 4.9%')
+    end
+
+    it 'rejects invalid path parameters and token shapes' do
+      sign_in_as(create(:user))
+
+      put '/users/theme_slots/system/4',
+          params: { tokens: 'not-object' },
+          as: :json
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json.fetch('errors')).to include(
+          'base_theme' => ['値が不正です．'])
+    end
+
+    it 'rejects non-object tokens for valid slots' do
+      sign_in_as(create(:user))
+
+      put '/users/theme_slots/light/1',
+          params: { tokens: 'not-object' },
+          as: :json
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json.fetch('errors')).to include(
+          'tokens' => ['JSON object で指定してください．'])
+    end
+  end
+end

backend/spec/requests/wiki_spec.rb

@@ -18,6 +18,13 @@ RSpec.describe 'Wiki API', type: :request do
         created_by_user: user,
         message: 'init')
   end
+  let!(:tag) do
+    Tag.create!(
+      tag_name: tn,
+      category: :general,
+      deprecated_at: Time.zone.local(2026, 6, 1)
+    )
+  end
 
   describe 'GET /wiki' do
     it 'returns wiki pages with title' do
@@ -30,6 +37,8 @@ RSpec.describe 'Wiki API', type: :request do
 
       expect(json[0]).to have_key('title')
       expect(json.map { |p| p['title'] }).to include('spec_wiki_title')
+      wiki_json = json.find { |item| item.fetch('id') == page.id }
+      expect(wiki_json.fetch('deprecated_at')).to eq(tag.deprecated_at.iso8601(3))
     end
   end
 
@@ -48,7 +57,8 @@ RSpec.describe 'Wiki API', type: :request do
 
         expect(json).to include(
             'id' => page.id,
-            'title' => 'spec_wiki_title')
+            'title' => 'spec_wiki_title',
+            'deprecated_at' => tag.deprecated_at.iso8601(3))
       end
     end
 
@@ -409,7 +419,11 @@ RSpec.describe 'Wiki API', type: :request do
         'kind' => 'content',
         'message' => 'r2'
       )
-      expect(top['wiki_page']).to include('id' => page.id, 'title' => 'spec_wiki_title')
+      expect(top['wiki_page']).to include(
+        'id' => page.id,
+        'title' => 'spec_wiki_title',
+        'deprecated_at' => tag.deprecated_at.iso8601(3)
+      )
       expect(top['user']).to include('id' => user.id, 'name' => user.name)
       expect(top).to have_key('timestamp')
 
@@ -479,6 +493,7 @@ RSpec.describe 'Wiki API', type: :request do
       expect(json).to include(
         'wiki_page_id' => page.id,
         'title' => 'spec_wiki_title',
+        'deprecated_at' => tag.deprecated_at.iso8601(3),
         'older_revision_id' => rev_a.id,
         'newer_revision_id' => rev_b.id
       )