#306

Reviewed-on: #379
Co-authored-by: miteruzo <miteruzo@naver.com>
Co-committed-by: miteruzo <miteruzo@naver.com>

AGENTS.md

@@ -12,16 +12,21 @@ BTRC Hub / タグ広場 is a split Rails API and React frontend repository.
 ## Stack
 
 - Backend: Ruby `3.2.2` from `backend/.ruby-version`, Rails `~> 8.0.2`.
-- Backend dependencies include `mysql2`, `sqlite3`, `rspec-rails`, `factory_bot_rails`, `rack-cors`, `jwt`, `discard`, `gollum`, `whenever`, `aws-sdk-s3`, `brakeman`, and `rubocop-rails-omakase`.
+- Backend dependencies include `mysql2`, `sqlite3`, `rspec-rails`,
+  `factory_bot_rails`, `rack-cors`, `jwt`, `discard`, `gollum`, `whenever`,
+  `aws-sdk-s3`, `brakeman`, and `rubocop-rails-omakase`.
 - Frontend: React `^19.1.0`, TypeScript `~5.8.3`, Vite `^6.3.5`.
-- Frontend data/UI dependencies include Axios, TanStack Query, Tailwind CSS, Framer Motion, Radix UI components, lucide-react, MDX/Markdown tooling, and Zustand.
+- Frontend data/UI dependencies include Axios, TanStack Query, Tailwind CSS,
+  Framer Motion, Radix UI components, lucide-react, MDX/Markdown tooling, and
+  Zustand.
 
 ## Main directories
 
 - `backend/app/controllers`: Rails API controllers.
 - `backend/app/models`: Active Record models.
 - `backend/app/representations`: API response representation classes.
-- `backend/app/services`: domain services such as version recording, wiki commit, YouTube sync, and similarity calculation.
+- `backend/app/services`: domain services such as version recording,
+  wiki commit, YouTube sync, and similarity calculation.
 - `backend/config/routes.rb`: API routes.
 - `backend/db/migrate`: migrations.
 - `backend/db/schema.rb`: current schema snapshot.
@@ -89,7 +94,8 @@ npm run test:run
 npm run preview
 ```
 
-`npm run build` runs `tsc -b && vite build`, then `postbuild` runs `node scripts/generate-sitemap.js`.
+`npm run build` runs `tsc -b && vite build`, then `postbuild` runs
+`node scripts/generate-sitemap.js`.
 
 `npm run test` runs Vitest in watch mode. Use `npm run test:run` for a non-watch frontend test run.
 
@@ -98,40 +104,164 @@ npm run preview
 - Prefer precise, minimal changes.
 - Do not flatter or over-explain.
 - Explain risks directly.
-- Prefer single quotes for strings unless interpolation or escaping makes double quotes better.
+- Prefer single quotes for strings unless interpolation or escaping makes
+  double quotes better.
 - 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`.
-- TypeScript and Python: use GNU-style spacing before parentheses where syntactically valid.
+- 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 `]`.
+- Keep the first element on the same line as `[` by default.
+- If an array would exceed the line limit, break after `[` and indent
+  elements by 4 spaces.
+- TypeScript and Python: use GNU-style spacing before parentheses where
+  syntactically valid.
+- Never write Ruby, TypeScript, or TSX lines longer than 99 characters.
+- Aim to keep Ruby, TypeScript, and TSX lines within 79 characters where practical.
+- TypeScript and TSX use 4-space logical indentation.
+- In TypeScript and TSX only, replace every leading run of 8 spaces with a tab.
+- 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 a function takes one destructured object
+  argument plus an inline type, prefer this shape when it fits locally:
+
+```ts
+const helper = (
+    { value, flag }: { value: string
+		       flag:  boolean },
+): Result => {
+  // ...
+}
+```
+
+- In TypeScript and TSX, put `switch` case block braces on their own lines
+  when a case needs a lexical block:
+
+```ts
+case 'yes':
+case 'no':
+  {
+    const expected = valueFor (item)
+    return expected == null || expected === answer
+  }
+```
+
+- In TypeScript and TSX, use `value == null` and `value != null` as the
+  default nullish checks. Do not use `=== null`, `=== undefined`,
+  `!== null`, or `!== undefined`.
+- If code appears to need a distinction between `null` and `undefined`, treat
+  that as a design smell and revise the logic to avoid the distinction.
+  External library APIs that explicitly require distinguishing the two are the
+  only exception.
+- In TypeScript and TSX, keep short arrays on one line when they fit under the
+  line limit; break arrays only when readability or line length requires it.
+- In TypeScript and TSX, when a ternary expression is split across multiple
+  lines, align `?` and `:` with the condition expression. Do not indent `?` and
+  `:` one extra level under the condition.
+
+```ts
+const value =
+    condition
+    ? consequent
+    : alternate
+```
+
+- In TypeScript and TSX, keep short ternary expressions on one line when they
+  fit cleanly under the line limit.
+- In TypeScript and TSX, prefer ternary expressions for simple conditional
+  value selection. Do not replace a clear ternary with `if` statements, and do
+  not introduce immediately invoked functions just to avoid or reformat a
+  ternary expression.
+- In TypeScript and TSX, do not write `let` followed by later `if` assignments
+  when the value can be expressed as a single `const` initializer. Prefer
+  `const` because it prevents accidental later reassignment.
+- When fixing formatting, change formatting only. Do not change expression
+  structure, control flow, or variable mutability unless the requested style
+  explicitly requires it.
 - Do not add production dependencies without explicit approval.
+- Do not create, modify, or run tests unless the user explicitly asks for
+  test work. When the user asks for tests, keep working and rerun them until
+  they pass or the remaining failure is clearly blocked.
 
 ## Backend rules
 
-- Inspect existing routes, controllers, models, services, and specs before editing backend behavior.
-- For API behavior changes, add or update request specs under `backend/spec/requests`.
-- Prefer RSpec for new backend tests; existing minitest files under `backend/test` do not make minitest the default for new coverage.
+- Inspect existing routes, controllers, models, services, and specs before
+  editing backend behavior.
+- 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 behavior 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.
 - Do not weaken authentication, BAN user checks, or IP BAN checks.
-- 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.
+- 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.
+- 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.
 
 ## Frontend rules
 
 - Use `frontend/src/lib/api.ts` for API calls so headers and camelCase conversion stay consistent.
-- Add or reuse TanStack Query keys through `frontend/src/lib/queryKeys.ts`; avoid ad hoc query key arrays.
+- Add or reuse TanStack Query keys through `frontend/src/lib/queryKeys.ts`;
+  avoid ad hoc query key arrays.
 - Encode URL path-segment values with `encodeURIComponent`.
 - React hooks must be called unconditionally.
-- Keep page-level code under `frontend/src/pages` and shared UI/feature code under `frontend/src/components` unless existing patterns point elsewhere.
+- 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.
+- 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 ellipses, prefer `……` over ASCII `...`.
 
 ### Frontend TSX style
 
-- Preserve the local TSX formatting style. Do not normalize TSX to common Prettier-style React formatting unless explicitly asked.
+- Preserve the local TSX formatting style.
+- Do not normalize TSX to common Prettier-style React formatting unless
+  explicitly asked.
 - 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 nested tag attributes with one tab relative to the tag line. With the project tab width, this visually appears as 4 spaces.
-- 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 does so.
-- Keep JSX closing parentheses in the existing compact style, for example `</div>)` rather than moving `)` onto a separate line.
+- 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.
+- A leading tab is exactly equivalent to 8 leading spaces.
+- 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
+  does so.
+- Keep JSX closing parentheses in the existing compact style, for example
+  `</div>)` rather than moving `)` onto a separate line.
+- Do not add braces around `if`, `else`, or `for` bodies when the body is a
+  single physical line.
+- Always add braces around `if`, `else`, or `for` bodies when the body spans
+  two or more physical lines, even if it is one statement.
+- Do not use a leading semicolon for expression statements such as
+  `;([...]).forEach(...)`; rewrite the expression to avoid ASI hazards
+  explicitly, for example with `void`.
 
 Preferred:
 
@@ -164,10 +294,15 @@ function PostFormTagsArea ({ tags, setTags }: Props) {
 
 - First inspect existing patterns; do not invent new architecture when a local convention exists.
 - Keep changes scoped to the requested issue.
-- 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.
-- If frontend code changes, run the existing frontend verification commands that apply: `npm run build`, `npm run lint`, and `npm run test:run`.
-- If backend code changes, run the relevant RSpec command; for broad backend changes, run `bundle exec rspec`.
+- 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.
+- 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.
+- If backend code changes, do not run RSpec unless the user explicitly asks
+  for tests.
 - If a verification command cannot be run or fails, report the exact command and failure.
 
 ## Completion criteria
@@ -175,7 +310,8 @@ function PostFormTagsArea ({ tags, setTags }: Props) {
 A task is complete only when:
 
 - implementation is complete,
-- relevant verification commands pass, or failures are clearly explained,
+- relevant non-test verification commands pass, or failures are clearly
+  explained,
 - unrelated files are not changed,
 - migrations and schema are consistent when schema changes are made,
 - user-facing behavior is documented when needed.

backend/AGENTS.md

@@ -4,7 +4,9 @@
 
 These rules apply to work under `backend/`.
 
-This is a Rails API app using Active Record, RSpec, request specs, service objects, representation classes, and version tables for post/tag/wiki history.
+This is a Rails API app using Active Record, RSpec, request specs,
+service objects, representation classes, and version tables for post/tag/wiki
+history.
 
 ## Commands
 
@@ -45,37 +47,72 @@ bundle exec rspec
 
 If a command cannot be run or fails, report the exact command and failure.
 
+Do not create, modify, or run tests unless the user explicitly asks for test
+work. When the user asks for tests, keep working and rerun them until they
+pass or the remaining failure is clearly blocked.
+
 ## Rails structure
 
 - `app/controllers`: API controllers.
 - `app/models`: Active Record models and concerns.
 - `app/representations`: JSON response shaping.
-- `app/services`: domain services such as version recorders, wiki commit, YouTube sync, and similarity calculation.
+- `app/services`: domain services such as version recorders, wiki commit,
+  YouTube sync, and similarity calculation.
 - `config/routes.rb`: public API routes.
 - `db/migrate`: migrations.
 - `db/schema.rb`: schema snapshot.
 - `lib/tasks`: custom Rake tasks.
 - `spec`: RSpec tests.
 
-Before changing behavior, inspect the matching route, controller, model, service, representation, and spec.
+Before changing behavior, inspect the matching route, controller, model,
+service, representation, and spec.
 
 ## Ruby style
 
 - 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
+  dense.
+- For Ruby arrays, never put whitespace or a line break immediately before `]`.
+- Keep the first element on the same line as `[` by default.
+- If an array would exceed the line limit, break after `[` and indent
+  elements by 4 spaces.
+- For Ruby blocks, use 2-space indentation for the block body.
 - Keep comments short and useful; avoid narrating obvious code.
 - Do not add production dependencies without approval.
 
 ## Authentication and authorization
 
-- Authentication is handled through the `X-Transfer-Code` header in `ApplicationController#authenticate_user`.
+- Authentication is handled through the `X-Transfer-Code` header in
+  `ApplicationController#authenticate_user`.
 - `current_user` is set by looking up `User.inheritance_code`.
-- Do not bypass or weaken the `X-Transfer-Code` flow unless the task explicitly changes authentication.
-- Unauthenticated write actions should return `:unauthorized` consistently with existing controllers.
+- Do not bypass or weaken the `X-Transfer-Code` flow unless the task
+  explicitly changes authentication.
+- Unauthenticated write actions should return `:unauthorized` consistently
+  with existing controllers.
 - Role checks use `User` enum roles: `guest`, `member`, and `admin`.
-- Use `current_user.gte_member?` for member-or-admin write permissions where existing controllers do so.
+- Use `current_user.gte_member?` for member-or-admin write permissions where
+  existing controllers do so.
 - Use `current_user.admin?` only for admin-only paths, such as tag child relationship changes.
 - Do not replace role checks with looser presence checks.
 
@@ -88,7 +125,9 @@ Before changing behavior, inspect the matching route, controller, model, service
 - User and IP bans use `banned_at`, not a boolean `banned` column.
 - `User#banned?` and `IpAddress#banned?` check `banned_at.present?`.
 - Do not weaken BAN or IP BAN behavior.
-- If changing request authentication or controller before actions, add or update request specs covering banned users and banned IP addresses.
+- If changing request authentication or controller before actions, add or
+  update request specs covering banned users and banned IP addresses only when
+  the user explicitly asks for tests.
 
 ## RSpec
 
@@ -99,49 +138,88 @@ Before changing behavior, inspect the matching route, controller, model, service
 - Put Rake task coverage under `spec/tasks`.
 - `spec/rails_helper.rb` loads `spec/support/**/*.rb`.
 - Request specs include `AuthHelper` and `JsonHelper`.
-- `AuthHelper#sign_in_as(user)` stubs `ApplicationController#current_user`; use it when matching existing request spec style.
-- Add or update request specs for API behavior changes, especially status codes, permissions, response shape, and version conflict behavior.
+- `AuthHelper#sign_in_as(user)` stubs
+  `ApplicationController#current_user`; use it when matching existing
+  request spec style.
+- Add or update request specs for API behavior changes only when the user
+  explicitly asks for tests, especially status codes, permissions, response
+  shape, and version conflict behavior.
 
 ## Migrations
 
 - Keep migrations and `db/schema.rb` consistent.
 - Use reversible migrations where practical; otherwise define explicit `up` and `down`.
-- For data backfills inside migrations, follow the existing pattern of defining migration-local `ActiveRecord::Base` classes with `self.table_name`.
+- For data backfills inside migrations, follow the existing pattern of
+  defining migration-local `ActiveRecord::Base` classes with
+  `self.table_name`.
 - Preserve existing indexes, foreign keys, check constraints, and null constraints.
 - Be careful with MySQL-specific options already present in migrations, such as `after:`.
-- Do not edit old migrations just to change current behavior unless explicitly requested; add a new migration.
+- Do not edit old migrations just to change current behavior unless
+  explicitly requested; add a new migration.
 
 ## Version tables
 
 - Versioned records include posts, tags, nico tags, and wiki pages.
-- Current records have `version_no`; version tables have positive `version_no` with unique indexes scoped to the parent record.
+- Current records have `version_no`; version tables have positive
+  `version_no` with unique indexes scoped to the parent record.
 - Version event types are `create`, `update`, `discard`, and `restore`.
 - Version rows are readonly through the `VersionRecord` concern.
-- Use the existing recorder services instead of manually inserting version rows in application code:
+- Use the existing recorder services instead of manually inserting version
+  rows in application code:
   - `PostVersionRecorder`
   - `TagVersionRecorder`
   - `NicoTagVersionRecorder`
   - `WikiVersionRecorder`
   - `TagVersioning`
-- `VersionRecorder` locks the current record, validates sequence consistency, skips unchanged update snapshots, creates the next version row, and updates the record `version_no`.
+- `VersionRecorder` locks the current record, validates sequence consistency,
+  skips unchanged update snapshots, creates the next version row, and updates
+  the record `version_no`.
 - Do not update versioned records without considering whether a version snapshot must be created.
-- For optimistic concurrency paths, preserve `base_version_no`, `force`, and `merge` semantics and cover conflicts in request specs.
+- For optimistic concurrency paths, preserve `base_version_no`, `force`, and
+  `merge` semantics. Cover conflicts in request specs only when the user
+  explicitly asks for tests.
 
 ## Domain cautions
 
-- Posts have tag snapshots, parent post implications, original-created ranges, viewed state, and version conflict behavior.
-- Tags have canonical names, aliases through `TagName`, categories, parent implications, discard behavior, and version snapshots.
-- Nico tags have separate relation/version behavior; do not treat them like normal editable tags without checking existing code.
-- Wiki pages involve page content, revisions/history, version rows, title/tag-name behavior, and diff/restore paths.
-- Materials, theatres, and comments have user and permission checks; inspect the controller before changing them.
+- Posts have tag snapshots, parent post implications, original-created ranges,
+  viewed state, and version conflict behavior.
+- Tags have canonical names, aliases through `TagName`, categories, parent
+  implications, discard behavior, and version snapshots.
+- Nico tags have separate relation/version behavior; do not treat them like
+  normal editable tags without checking existing code.
+- Wiki pages involve page content, revisions/history, version rows,
+  title/tag-name behavior, and diff/restore paths.
+- Materials, theatres, and comments have user and permission checks; inspect
+  the controller before changing them.
 
 ## API responses
 
 - Use representation classes under `app/representations` when existing endpoints do.
-- Keep response keys consistent with existing JSON contracts; frontend code expects camelCase conversion client-side, while Rails params and JSON keys are generally snake_case.
-- Preserve existing HTTP status conventions: `:unauthorized` for no user, `:forbidden` for insufficient role or banned user, `:not_found` for missing records, and `:unprocessable_entity` for validation failures.
+- Keep response keys consistent with existing JSON contracts.
+- Frontend code expects camelCase conversion client-side, while Rails params
+  and JSON keys are generally snake_case.
+- Preserve existing HTTP status conventions:
+  `:unauthorized` for no user, `:forbidden` for insufficient role or banned
+  user, `:not_found` for missing records, and `:unprocessable_entity` for
+  validation failures.
+- For diagnostic or internal helper JSON, prefer a deliberately light response
+  shape over full representation classes when callers only need identifiers,
+  labels, URLs, or weights.
+
+## Active Record performance
+
+- When a controller action serializes nested associations, preload the
+  associations it will touch instead of allowing N+1 queries.
+- Be sensitive to N+1 queries in all backend work.
+- Avoid introducing N+1 queries, and proactively fix existing N+1 issues when
+  you find them in the code path you are editing.
+- When an association may already be preloaded, prefer loaded-association
+  checks that reuse the preloaded data without losing the efficient database
+  path.
 
 ## Files to avoid in routine work
 
-- Do not inspect or edit `tmp/`, `log/`, `storage/`, `vendor/`, or dependency directories unless explicitly needed.
-- Do not modify generated schema or migration output without the corresponding migration when schema changes are made.
+- Do not inspect or edit `tmp/`, `log/`, `storage/`, `vendor/`, or dependency
+  directories unless explicitly needed.
+- Do not modify generated schema or migration output without the corresponding
+  migration when schema changes are made.

backend/app/controllers/gekanator_games_controller.rb

@@ -0,0 +1,272 @@
+class GekanatorGamesController < ApplicationController
+  def create
+    return head :unauthorized unless current_user
+
+    guessed_post_id = params.require(:guessed_post_id)
+    correct_post_id = params[:correct_post_id].presence
+    answers = params.require(:answers).as_json
+
+    game = GekanatorGame.new(
+        user: current_user,
+        guessed_post_id:,
+        correct_post_id:,
+        won: correct_post_id.present? && guessed_post_id.to_i == correct_post_id.to_i,
+        question_count: answers.length,
+        answers:)
+
+    if game.invalid?
+      render json: { errors: game.errors.full_messages }, status: :unprocessable_entity
+      return
+    end
+
+    learned_example_count = 0
+
+    ActiveRecord::Base.transaction do
+      game.save!
+      learned_example_count = learn_answers_from_game!(game)
+    end
+
+    render json: {
+      id: game.id,
+      learned_example_count:
+    }, status: :created
+  rescue ActiveRecord::RecordInvalid => e
+    render json: { errors: e.record.errors.full_messages }, status: :unprocessable_entity
+  end
+
+  def extra_questions
+    game = find_owned_game
+    return if performed?
+
+    questions =
+        GekanatorQuestion
+        .accepted
+        .includes(:gekanator_question_examples)
+        .where(kind: 'post_similarity', source: 'user_suggested')
+        .to_a
+
+    selected =
+        prioritized_extra_questions(
+            questions,
+            post_id: game.correct_post_id,
+            user: current_user,
+            limit: 6)
+
+    render json: {
+      questions: selected.map { |question| extra_question_json(question) }
+    }
+  end
+
+  def extra_question_answers
+    game = find_owned_game
+    return if performed?
+
+    answer_params = params.require(:answers)
+    if !answer_params.is_a?(Array)
+      return render_validation_error fields: { answers: ['配列で指定してください．'] }
+    end
+
+    answers = answer_params.map { |answer|
+      {
+        question_id: answer.require(:question_id).to_i,
+        answer: answer.require(:answer)
+      }
+    }
+    questions = GekanatorQuestion.where(id: answers.map { _1[:question_id] })
+    question_by_id = questions.index_by(&:id)
+    if questions.length != answers.length
+      return render_validation_error fields: { answers: ['質問が見つかりません．'] }
+    end
+    if questions.any? { |question| question.status != 'accepted' || question.kind != 'post_similarity' }
+      return render_validation_error fields: { answers: ['質問が不正です．'] }
+    end
+
+    ActiveRecord::Base.transaction do
+      answers.each do |item|
+        question = question_by_id[item[:question_id]]
+        example =
+            GekanatorQuestionExample.find_or_initialize_by(
+                gekanator_question: question,
+                post: game.correct_post,
+                user: current_user)
+        example.record_answer!(
+            answer: item[:answer],
+            source: 'post_game_extra',
+            gekanator_game: game)
+        example.save!
+      end
+    end
+
+    render json: { count: answers.length }, status: :created
+  end
+
+  private
+
+  def extra_question_json question
+    {
+      id: question.id,
+      text: question.text,
+      source: question.source,
+      priority_weight: question.priority_weight
+    }
+  end
+
+  def prioritized_extra_questions questions, post_id:, user:, limit:
+    answered_question_ids =
+        GekanatorQuestionExample
+        .where(user:, gekanator_question_id: questions.map(&:id))
+        .distinct
+        .pluck(:gekanator_question_id)
+    unanswered, answered =
+        questions.partition { |question| !answered_question_ids.include?(question.id) }
+    selected = weighted_sample_questions(unanswered, post_id:, limit:)
+    return selected if selected.length >= limit
+
+    selected + weighted_sample_questions(
+        answered.reject { |question| selected.any? { _1.id == question.id } },
+        post_id:,
+        limit: limit - selected.length)
+  end
+
+  def weighted_sample_questions questions, post_id:, limit:
+    remaining = questions.uniq(&:id)
+    selected = []
+
+    while selected.length < limit && remaining.any?
+      weighted =
+          remaining.map { |question|
+            [question, selection_weight_for(question, post_id: post_id)]
+          }
+      total_weight = weighted.sum { |_question, weight| weight }
+      break if total_weight <= 0
+
+      target = rand * total_weight
+      cumulative = 0.0
+      chosen =
+          weighted.find do |_question, weight|
+            cumulative += weight
+            cumulative >= target
+          end&.first || weighted.first.first
+
+      selected << chosen
+      remaining.reject! { |question| question.id == chosen.id }
+    end
+
+    selected
+  end
+
+  def selection_weight_for question, post_id:
+    sample_count =
+        question.gekanator_question_examples.sum { |example|
+          next 0 unless example.post_id == post_id
+
+          example.sample_count.presence || 1
+        }
+
+    question.priority_weight.to_f / (1.0 + sample_count * 0.15)
+  end
+
+  def find_owned_game
+    return head :unauthorized unless current_user
+
+    game = GekanatorGame.find_by(id: params[:id])
+    return head :not_found unless game
+    if !current_user.admin? && game.user_id != current_user.id
+      return head :not_found
+    end
+
+    game
+  end
+
+  def learn_answers_from_game! game
+    correct_post = game.correct_post
+    return 0 if correct_post.blank?
+
+    accepted_questions =
+        GekanatorQuestion
+        .accepted
+        .index_by { |question| public_question_id_for(question) }
+    learned_count = 0
+
+    Array(game.answers).each do |answer|
+      answer_value = answer['answer'].to_s
+      next if answer_value.blank? || answer_value == 'unknown'
+
+      question_id = game_answer_question_id(answer)
+      next if question_id.blank?
+
+      question = accepted_questions[question_id.to_s]
+      next unless learnable_game_answer_question?(question)
+
+      example =
+          GekanatorQuestionExample.find_or_initialize_by(
+              gekanator_question: question,
+              post: correct_post,
+              user: current_user)
+      example.record_answer!(
+          answer: answer_value,
+          source: 'post_game_answer',
+          gekanator_game: game)
+      example.save!
+      learned_count += 1
+    end
+
+    learned_count
+  end
+
+  def public_question_id_for question
+    condition = normalize_condition(question.condition)
+
+    case condition[:type]
+    when 'tag'
+      "tag:#{condition[:key]}"
+    when 'source'
+      "source:#{condition[:host]}"
+    when 'original-year'
+      "original-year:#{condition[:year]}"
+    when 'original-month'
+      "original-month:#{condition[:month]}"
+    when 'original-month-day'
+      "original-month-day:#{condition[:monthDay] || condition[:month_day]}"
+    when 'title-length-at-least'
+      "title:length-at-least:#{condition[:length]}"
+    when 'title-length-greater-than'
+      "title:length-at-least:#{condition[:length].to_i + 1}"
+    when 'title-has-ascii'
+      'title:ascii'
+    when 'title-contains'
+      "title:contains:#{condition[:text]}"
+    when 'post-similarity'
+      "post-similarity:#{question.id}"
+    else
+      "catalog:#{question.id}"
+    end
+  end
+
+  def normalize_condition condition
+    json = condition.deep_dup.as_json
+
+    if json['type'] == 'original-month-day' && json['monthDay'].blank?
+      json['monthDay'] = json.delete('month_day')
+    end
+
+    json.deep_symbolize_keys
+  end
+
+  def learnable_game_answer_question? question
+    return false if question.nil?
+    return true if question.kind == 'post_similarity'
+    return false unless question.kind == 'tag'
+
+    condition = normalize_condition(question.condition)
+    key = condition[:key].to_s
+    !key.start_with?('nico:')
+  end
+
+  def game_answer_question_id answer
+    answer['question_id'] ||
+      answer[:question_id] ||
+      answer['questionId'] ||
+      answer[:questionId]
+  end
+end

backend/app/controllers/gekanator_posts_controller.rb

@@ -0,0 +1,71 @@
+class GekanatorPostsController < ApplicationController
+  def index
+    posts =
+        Post
+        .preload(:post_similarities, tags: :tag_name)
+        .with_attached_thumbnail
+        .order(Arel.sql(
+            'COALESCE(posts.original_created_before - INTERVAL 1 MINUTE, ' \
+            'posts.original_created_from, posts.created_at) DESC, posts.id DESC'))
+        .to_a
+
+    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, active_tags_by_post_id:
+    {
+      id: post.id,
+      url: post.url,
+      title: post.title,
+      thumbnail: thumbnail_url(post),
+      thumbnail_base: post.thumbnail_base,
+      original_created_from: post.original_created_from,
+      original_created_before: post.original_created_before,
+      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,
+      name: tag.name,
+      category: tag.category
+    }
+  end
+
+  def thumbnail_url post
+    return nil unless post.thumbnail.attached?
+
+    rails_storage_proxy_url(post.thumbnail, only_path: false)
+  rescue
+    nil
+  end
+end

backend/app/controllers/gekanator_question_suggestions_controller.rb

@@ -0,0 +1,95 @@
+class GekanatorQuestionSuggestionsController < ApplicationController
+  def create
+    return head :unauthorized unless current_user
+
+    game = GekanatorGame.find_by(id: params.require(:gekanator_game_id))
+    return head :not_found unless game
+    if !current_user.admin? && game.user_id != current_user.id
+      return head :not_found
+    end
+
+    existing_question_id = params[:existing_question_id].presence
+    if existing_question_id
+      question = GekanatorQuestion.accepted.find_by(id: existing_question_id)
+      return head :not_found unless question
+      unless learnable_existing_question?(question)
+        return render_validation_error fields: { existing_question_id: ['質問が不正です．'] }
+      end
+
+      example =
+          GekanatorQuestionExample.find_or_initialize_by(
+              gekanator_question: question,
+              post: game.correct_post,
+              user: current_user)
+      example.record_answer!(
+          answer: params.require(:answer),
+          source: 'post_game_extra',
+          gekanator_game: game)
+
+      if example.save
+        render json: {
+          id: question.id,
+          count: game.question_suggestions.count
+        }, status: :created
+      else
+        render_validation_error example
+      end
+      return
+    end
+
+    suggestion = GekanatorQuestionSuggestion.new(
+        gekanator_game: game,
+        user: current_user,
+        question_text: params.require(:question_text),
+        answer: params.require(:answer))
+
+    if suggestion.valid?
+      ActiveRecord::Base.transaction do
+        suggestion.save!
+        Gekanator::QuestionSuggestionPromoter.call(
+            suggestion: suggestion,
+            user: current_user)
+      end
+
+      render json: {
+        id: suggestion.id,
+        count: game.question_suggestions.count
+      }, status: :created
+    else
+      render_validation_error suggestion
+    end
+  end
+
+  def ai_convert
+    return head :not_found unless current_user&.admin?
+
+    suggestion = GekanatorQuestionSuggestion.find_by(id: params[:id])
+    return head :not_found unless suggestion
+    if Gekanator::AiRunBudget.exceeded_after_next_run?
+      suggestion.gekanator_ai_runs.create!(
+          model: 'budget_guard',
+          status: 'blocked_budget',
+          input_tokens: 0,
+          output_tokens: 0,
+          estimated_cost_jpy: 0)
+      return head :payment_required
+    end
+
+    Gekanator::QuestionSuggestionAiConverter.call(
+        suggestion: suggestion,
+        user: current_user)
+    head :no_content
+  rescue NotImplementedError
+    head :not_implemented
+  end
+
+  private
+
+  def learnable_existing_question? question
+    return true if question.kind == 'post_similarity'
+    return false unless question.kind == 'tag'
+
+    key = question.condition.as_json['key'].to_s
+    !key.start_with?('nico:')
+  end
+end

backend/app/controllers/gekanator_questions_controller.rb

@@ -0,0 +1,147 @@
+class GekanatorQuestionsController < ApplicationController
+  def index
+    questions =
+        GekanatorQuestion
+        .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.filter_map { |question|
+        json = question_json(question)
+        next if hidden_question?(json[:condition], deprecated_tag_keys)
+
+        json
+      }
+    }
+  end
+
+  private
+
+  def question_json question
+    condition = condition_json(question.condition).deep_symbolize_keys
+    json = {
+      record_id: question.id,
+      id: question_id_for(question, condition),
+      text: question_text_for(question, condition),
+      kind: question.kind,
+      condition: condition,
+      source: question.source,
+      priority_weight: question.priority_weight
+    }
+    if question.kind == 'post_similarity' || question.kind == 'tag'
+      json[:example_answers] = example_answers_json(question)
+    end
+    json
+  end
+
+  def question_id_for question, condition
+    case condition[:type]
+    when 'tag'
+      "tag:#{ condition[:key] }"
+    when 'source'
+      "source:#{ condition[:host] }"
+    when 'original-year'
+      "original-year:#{ condition[:year] }"
+    when 'original-month'
+      "original-month:#{ condition[:month] }"
+    when 'original-month-day'
+      "original-month-day:#{ condition[:monthDay] || condition[:month_day] }"
+    when 'title-length-at-least'
+      "title:length-at-least:#{ condition[:length] }"
+    when 'title-length-greater-than'
+      "title:length-at-least:#{ condition[:length].to_i + 1 }"
+    when 'title-has-ascii'
+      'title:ascii'
+    when 'title-contains'
+      "title:contains:#{ condition[:text] }"
+    when 'post-similarity'
+      "post-similarity:#{ question.id }"
+    else
+      "catalog:#{ question.id }"
+    end
+  end
+
+  def condition_json condition
+    json = condition.deep_dup.as_json
+
+    if json['type'] == 'original-month-day' && json['monthDay'].blank?
+      json['monthDay'] = json.delete('month_day')
+    end
+
+    if json['type'] == 'title-length-greater-than'
+      json['type'] = 'title-length-at-least'
+      json['length'] = json['length'].to_i + 1
+    end
+
+    json
+  end
+
+  def question_text_for question, condition
+    return question.text unless question.kind == 'title'
+
+    case condition[:type]
+    when 'title-length-at-least'
+      "タイトルは #{ condition[:length] } 文字以上?"
+    when 'title-contains'
+      "題名に「#{ condition[:text] }」が含まれる?"
+    else
+      question.text
+    end
+  end
+
+  def example_answers_json question
+    question
+        .gekanator_question_examples
+        .group_by(&:post_id)
+        .transform_values { |examples| aggregate_answer(examples) }
+  end
+
+  def aggregate_answer examples
+    examples
+        .group_by(&:answer)
+        .map { |answer, grouped| [answer, grouped.sum(&:weight), grouped.max_by(&:updated_at)&.updated_at] }
+        .sort_by { |(_answer, weight, updated_at)| [-weight, -(updated_at&.to_f || 0)] }
+        .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/materials_controller.rb

@@ -1,4 +1,8 @@
 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
@@ -11,7 +15,7 @@ class MaterialsController < ApplicationController
     tag_id = params[:tag_id].presence
     parent_id = params[:parent_id].presence
 
-    q = Material.includes(:tag, :created_by_user).with_attached_file
+    q = Material.includes(:tag, :created_by_user, :material_export_items).with_attached_file
     q = q.where(tag_id:) if tag_id
     q = q.where(parent_id:) if parent_id
 
@@ -24,7 +28,7 @@ class MaterialsController < ApplicationController
   def show
     material =
         Material
-        .includes(:tag)
+        .includes(:tag, :material_export_items)
         .with_attached_file
         .find_by(id: params[:id])
     return head :not_found unless material
@@ -36,26 +40,44 @@ class MaterialsController < ApplicationController
 
   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_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
+        tag = tag_name.tag
+        tag = Tag.create!(tag_name:, category: :material) unless tag
 
-    if material.save
+        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!
+        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
       render json: MaterialRepr.base(material, host: request.base_url), status: :created
     else
       render_validation_error material
@@ -71,29 +93,43 @@ 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_name = TagName.find_undiscard_or_create_by!(name: tag_name_raw)
+        tag = tag_name.tag
+        tag = Tag.create!(tag_name:, category: :material) unless tag
+
+        material.assign_attributes(tag:, url:, updated_by_user: current_user)
+        if uploaded_blob
+          material.file.attach(uploaded_blob)
+          clear_file_suppression!(material)
+        elsif params.key?(:url) && url.present? && file.blank?
+          material.file.detach
+        end
+        material.save!
+        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
+    render json: MaterialRepr.base(material, host: request.base_url)
   end
 
   def destroy
@@ -103,7 +139,146 @@ 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
+
+  def suppress_file
+    return head :unauthorized unless current_user
+    return head :forbidden unless current_user.admin?
+
+    material = Material.with_attached_file.find_by(id: params[:id])
+    return head :not_found unless material
+
+    reason = params[:reason].to_s.strip.presence
+    return render_unprocessable_entity('理由は必須です．', field: :reason) unless reason
+    purge = bool?(:purge)
+    file_snapshot = purge_material_file_snapshot(material) if purge
+    attachment = purge && material.file.attached? ? material.file.attachment : nil
+
+    Material.transaction do
+      MaterialVersionRecorder.ensure_snapshot!(material, created_by_user: current_user)
+      material.update!(file_suppressed_at: Time.current,
+                       file_suppressed_by_user: current_user,
+                       file_suppression_reason: reason,
+                       updated_by_user: current_user)
+      MaterialVersionRecorder.record!(material:, event_type: :suppress,
+                                      created_by_user: current_user,
+                                      file_snapshot:)
+    end
+    # Enqueue failure raises here after the suppress metadata has been committed.
+    # In that case the file remains suppressed in UI/ZIP and purge can be retried.
+    attachment&.purge_later
+    material.reload if purge
+
+    render json: MaterialRepr.base(material, host: request.base_url)
+  end
+
+  private
+
+  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,
+    )
+
+    if file_sha256.present?
+      blob.metadata['sha256'] = file_sha256
+      blob.save! if blob.changed?
+    end
+
+    blob
+  ensure
+    file.tempfile.rewind if file&.tempfile
+  end
+
+  def clear_file_suppression! material
+    material.file_suppressed_at = nil
+    material.file_suppressed_by_user = nil
+    material.file_suppression_reason = nil
+  end
+
+  def purge_material_file_snapshot material
+    return nil unless material.file.attached?
+
+    blob = material.file.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: blob.metadata['sha256'] ||
+                   MaterialFileSha256.from_blob(blob, allow_download: true) }
+  end
+
+  def render_material_import_block block
+    render_validation_error fields: { file: ["抑止された素材です: #{ block.reason }"] }
+  end
 end

backend/app/controllers/posts_controller.rb

@@ -44,7 +44,8 @@ class PostsController < ApplicationController
         filtered_posts
         .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, tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
+        .preload(:uploaded_user, :parents, :children,
+                 tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
         .with_attached_thumbnail
 
     q = q.where('posts.url LIKE ?', "%#{ url }%") if url
@@ -95,7 +96,7 @@ class PostsController < ApplicationController
   end
 
   def random
-    post = filtered_posts.preload(:uploaded_user,
+    post = filtered_posts.preload(:uploaded_user, :parents, :children,
                                   tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
                          .with_attached_thumbnail
                          .order('RAND()')
@@ -108,7 +109,8 @@ class PostsController < ApplicationController
   def show
     post =
         Post
-        .includes(:uploaded_user, tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
+        .includes(:uploaded_user, :parents, :children,
+                  tags: [:deerjikists, :materials, { tag_name: :wiki_page }])
         .with_attached_thumbnail
         .find_by(id: params[:id])
     return head :not_found unless post
@@ -146,10 +148,10 @@ class PostsController < ApplicationController
     ApplicationRecord.transaction do
       post.save!
 
-      tags = Tag.normalise_tags!(tag_names)
+      tags = Tag.normalise_tags!(tag_names, deny_deprecated: true)
       TagVersioning.record_tag_snapshots!(tags, created_by_user: current_user)
 
-      tags = Tag.expand_parent_tags(tags)
+      tags = Tag.expand_parent_tags(tags).reject(&:deprecated?)
       sync_post_tags!(post, tags)
 
       sync_parent_posts!(post, parent_post_ids)
@@ -163,6 +165,8 @@ 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 ArgumentError => e
     render_validation_error fields: { parent_post_ids: [e.message] }
   rescue ActiveRecord::RecordInvalid => e
@@ -253,6 +257,8 @@ class PostsController < ApplicationController
     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 ArgumentError => e
     render_validation_error fields: { parent_post_ids: [e.message] }
   rescue ActiveRecord::RecordInvalid => e
@@ -376,7 +382,7 @@ class PostsController < ApplicationController
   end
 
   def build_tag_tree_for tags
-    tags = tags.to_a
+    tags = tags.reject(&:deprecated?).to_a
     tag_ids = tags.map(&:id)
 
     implications = TagImplication.where(parent_tag_id: tag_ids, tag_id: tag_ids)
@@ -499,7 +505,8 @@ 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.tags.not_nico.where(deprecated_at: nil)
+        .joins(:tag_name).order('tag_names.name').pluck('tag_names.name')
   end
 
   def post_incoming_snapshot title:, original_created_from:, original_created_before:,
@@ -531,9 +538,10 @@ class PostsController < ApplicationController
   end
 
   def incoming_tag_names_for_snapshot raw_tag_names
-    tags = Tag.normalise_tags!(raw_tag_names, with_tagme: false)
+    tags = Tag.normalise_tags!(raw_tag_names, with_tagme: false,
+                                              deny_deprecated: true)
 
-    Tag.expand_parent_tags(tags).map(&:name).uniq.sort
+    Tag.expand_parent_tags(tags).reject(&:deprecated?).map(&:name).uniq.sort
   end
 
   def post_conflict_json post:, base_version_no:, base_snapshot:,
@@ -620,13 +628,14 @@ class PostsController < ApplicationController
                  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)
+    editable_tags = Tag.normalise_tags!(snapshot[:tag_names], with_tagme: false,
+                                                               deny_deprecated: true)
     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)
     sync_parent_posts!(post, snapshot[:parent_post_ids])

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]
@@ -77,37 +83,27 @@ class TagsController < ApplicationController
     parent_tag_id = params[:parent].to_i
     parent_tag_id = nil if parent_tag_id <= 0
 
+    graph = build_with_depth_graph
+
     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: [])
+      TagRepr.base(tag).merge(has_children: visible_child_tag_ids(tag.id, graph).present?,
+                              children: [])
     }
   end
 
@@ -133,6 +129,7 @@ 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 =
@@ -252,18 +249,24 @@ 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)
+    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
 
     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)
@@ -272,7 +275,11 @@ class TagsController < ApplicationController
       name_changed = name != old_name
       wiki_page = tag.tag_name.wiki_page if name_changed
 
-      tag.update!(category:)
+      if tag.deprecated? == deprecated
+        tag.update!(category:)
+      else
+        tag.update!(category:, deprecated_at: deprecated ? Time.current : nil)
+      end
       tag.tag_name.update!(name:)
 
       alias_names << old_name if name_changed
@@ -300,11 +307,17 @@ 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
+
     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
@@ -316,6 +329,9 @@ class TagsController < ApplicationController
 
       tag.tag_name.update!(name:) if name.present?
       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 +348,99 @@ class TagsController < ApplicationController
 
   private
 
+  def build_with_depth_graph
+    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
+
+    tags_by_id = Tag.where(id: tag_ids)
+                    .pluck(:id, :category, :deprecated_at)
+                    .each_with_object({ }) do |(id, category, deprecated_at), h|
+      h[id] = { category:, deprecated: deprecated_at.present? }
+    end
+
+    { children_by_parent_id:, parent_ids_by_child_id:, tags_by_id:,
+      visible_child_tag_ids_by_parent_id: { } }
+  end
+
+  def visible_root_tag_ids graph
+    graph[:tags_by_id].filter_map do |tag_id, attrs|
+      next unless with_depth_visible_tag?(attrs)
+      next unless visible_root_tag?(tag_id, graph)
+
+      tag_id
+    end
+  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
+
+    visible_ids << tag_id if with_depth_visible_tag?(tag)
+  end
+
+  def with_depth_visible_tag? tag
+    tag[:category].in?(['meme', 'character', 'material']) && !tag[:deprecated]
+  end
+
   def build_tag_children tag
     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
-    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:))
+        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

backend/app/controllers/theatre_comments_controller.rb

@@ -1,14 +1,21 @@
 class TheatreCommentsController < ApplicationController
   def index
+    limit = params[:limit].to_i
+    limit = 20 if limit <= 0
+
     no_gt = params[:no_gt].to_i
-    no_gt = 0 if no_gt.negative?
+    no_gt = 0 if no_gt < 0
 
     comments = TheatreComment
                .where(theatre_id: params[:theatre_id])
                .where('no > ?', no_gt)
                .order(no: :desc)
+               .limit(limit)
 
-    render json: comments.as_json(include: { user: { only: [:id, :name] } })
+    render json: comments.map {
+      _1.as_json(include: { user: { only: [:id, :name] } })
+          .merge(content: _1.discarded? ? nil : _1.content, deleted: _1.discarded?)
+    }
   end
 
   def create
@@ -29,4 +36,19 @@ class TheatreCommentsController < ApplicationController
 
     render json: comment, status: :created
   end
+
+  def destroy
+    return head :unauthorized unless current_user
+
+    theatre_id = params[:theatre_id].to_i
+    no = params[:id].to_i
+
+    comment = TheatreComment.find_by(theatre_id:, no:)
+    return head :not_found unless comment
+    return head :forbidden unless comment.user == current_user
+
+    comment.discard!
+
+    head :no_content
+  end
 end

backend/app/controllers/theatre_programmes_controller.rb

@@ -0,0 +1,22 @@
+class TheatreProgrammesController < ApplicationController
+  def index
+    limit = params[:limit].to_i
+    limit = 100 if limit <= 0
+
+    position_gt = params[:position_gt].to_i
+    position_gt = 0 if position_gt < 0
+
+    programmes = TheatreProgramme
+                 .where(theatre_id: params[:theatre_id])
+                 .where('position > ?', position_gt)
+                 .includes(:post)
+                 .order(position: :desc).limit(100)
+                 .limit(limit)
+
+    render json: programmes.map { |programme|
+      programme.as_json.merge(post: { id: programme.post.id,
+                                      title: programme.post.title,
+                                      url: programme.post.url })
+    }
+  end
+end

backend/app/controllers/theatre_skip_events_controller.rb

@@ -0,0 +1,22 @@
+class TheatreSkipEventsController < ApplicationController
+  def index
+    limit = params[:limit].to_i
+    limit = 50 if limit <= 0
+
+    events =
+        TheatreSkipEvent
+        .where(theatre_id: params[:theatre_id])
+        .includes(:post, tags: :tag_name)
+        .order(created_at: :desc)
+        .limit(limit)
+
+    render json: events.map { |event|
+      { id: event.id,
+        theatre_id: event.theatre_id,
+        post: { id: event.post.id, title: event.post.title, url: event.post.url },
+        tags: event.tags.map { |tag| { id: tag.id, name: tag.name } },
+        programme_position: event.programme_position,
+        created_at: event.created_at }
+    }
+  end
+end

backend/app/controllers/theatres_controller.rb

@@ -31,9 +31,7 @@ class TheatresController < ApplicationController
       post_started_at = theatre.current_post_started_at
     end
 
-    render json: {
-        host_flg:, post_id:, post_started_at:,
-        watching_users: theatre.watching_users.as_json(only: [:id, :name]) }
+    render json: theatre_info_json(theatre, host_flg:, post_id:, post_started_at:)
   end
 
   def next_post
@@ -43,12 +41,119 @@ class TheatresController < ApplicationController
     return head :not_found unless theatre
     return head :forbidden if theatre.host_user != current_user
 
-    post = Post.where("url LIKE '%nicovideo.jp%'")
-           .or(Post.where("url LIKE '%youtube.com%'"))
-           .order('RAND()')
-           .first
-    theatre.update!(current_post: post, current_post_started_at: Time.current)
+    ApplicationRecord.transaction do
+      theatre.lock!
+      TheatrePostAdvancer.call(theatre:)
+    end
 
     head :no_content
   end
+
+  def skip_vote
+    return head :unauthorized unless current_user
+
+    theatre = Theatre.find_by(id: params[:id])
+    return head :not_found unless theatre
+    requested_post_id = params[:post_id].to_i
+    return head :unprocessable_entity if requested_post_id <= 0
+
+    skipped = false
+    conflicted = false
+
+    ApplicationRecord.transaction do
+      theatre.lock!
+      if theatre.current_post
+        TheatreWatchingUser.find_or_initialize_by(theatre:, user: current_user).tap {
+          _1.expires_at = 30.seconds.from_now
+        }.save!
+
+        if theatre.current_post_id != requested_post_id
+          conflicted = true
+          next
+        end
+
+        TheatreSkipVote.find_or_create_by!(theatre:, post_id: requested_post_id, user: current_user)
+
+        vote_status = skip_vote_status(theatre)
+        if vote_status[:votes_count] >= vote_status[:required_count]
+          TheatreSkipFinalizer.call(theatre:, user: current_user)
+          TheatrePostAdvancer.call(theatre:)
+          skipped = true
+        end
+      end
+    end
+
+    theatre.reload
+    return render json: theatre_info_json(theatre, skipped: false), status: :conflict if conflicted
+
+    render json: theatre_info_json(theatre, skipped:)
+  end
+
+  def unskip_vote
+    return head :unauthorized unless current_user
+
+    theatre = Theatre.find_by(id: params[:id])
+    return head :not_found unless theatre
+    requested_post_id = params[:post_id].to_i
+    return head :unprocessable_entity if requested_post_id <= 0
+
+    conflicted = false
+
+    theatre.with_lock do
+      if theatre.current_post
+        if theatre.current_post_id != requested_post_id
+          conflicted = true
+        else
+          TheatreSkipVote.where(theatre:, post_id: requested_post_id, user: current_user).delete_all
+        end
+      end
+    end
+
+    theatre.reload
+    return render json: theatre_info_json(theatre, skipped: false), status: :conflict if conflicted
+
+    render json: theatre_info_json(theatre, skipped: false)
+  end
+
+  def post_selection_weights
+    theatre = Theatre.find_by(id: params[:id])
+    return head :not_found unless theatre
+
+    render json: TheatrePostSelector.new(theatre:).weight_json
+  end
+
+  private
+
+  def theatre_info_json(theatre, host_flg: nil, post_id: nil, post_started_at: nil, skipped: nil)
+    host_flg = theatre.host_user_id == current_user&.id if host_flg.nil?
+    post_id = theatre.current_post_id if post_id.nil?
+    post_started_at = theatre.current_post_started_at if post_started_at.nil?
+
+    json = { host_flg:,
+             post_id:,
+             post_started_at:,
+             post_elapsed_ms: post_started_at ? ((Time.current - post_started_at) * 1000).floor : nil,
+             watching_users: theatre.watching_users.as_json(only: [:id, :name]),
+             skip_vote: skip_vote_status(theatre) }
+    json[:skipped] = skipped unless skipped.nil?
+    json
+  end
+
+  def skip_vote_status(theatre)
+    watching_user_ids = theatre.watching_users.ids
+    watching_users_count = watching_user_ids.size
+    required_count = (watching_users_count / 2) + 1
+    post = theatre.current_post
+    votes =
+        if post
+          TheatreSkipVote.where(theatre:, post:, user_id: watching_user_ids)
+        else
+          TheatreSkipVote.none
+        end
+
+    { votes_count: post ? votes.count : 0,
+      required_count:,
+      watching_users_count:,
+      voted: post && current_user ? votes.exists?(user_id: current_user.id) : false }
+  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/gekanator_ai_run.rb

@@ -0,0 +1,21 @@
+class GekanatorAiRun < ApplicationRecord
+  STATUSES = ['pending', 'running', 'succeeded', 'failed', 'blocked_budget'].freeze
+
+  belongs_to :gekanator_question_suggestion
+
+  validates :model, presence: true, length: { maximum: 255 }
+  validates :status, presence: true, inclusion: { in: STATUSES }
+  validates :input_tokens,
+            presence: true,
+            numericality: { only_integer: true, greater_than_or_equal_to: 0 }
+  validates :output_tokens,
+            presence: true,
+            numericality: { only_integer: true, greater_than_or_equal_to: 0 }
+  validates :estimated_cost_jpy,
+            presence: true,
+            numericality: { greater_than_or_equal_to: 0 }
+
+  scope :this_month, lambda {
+    where(created_at: Time.current.beginning_of_month..Time.current.end_of_month)
+  }
+end

backend/app/models/gekanator_game.rb

@@ -0,0 +1,15 @@
+class GekanatorGame < ApplicationRecord
+  belongs_to :user
+  belongs_to :guessed_post, class_name: 'Post'
+  belongs_to :correct_post, class_name: 'Post'
+  has_many :question_suggestions,
+           class_name: 'GekanatorQuestionSuggestion',
+           dependent: :delete_all
+  has_many :question_examples,
+           class_name: 'GekanatorQuestionExample',
+           dependent: :delete_all
+
+  validates :answers, presence: true
+  validates :question_count, numericality: { greater_than_or_equal_to: 0 }
+  validates :won, inclusion: { in: [true, false] }
+end

backend/app/models/gekanator_question.rb

@@ -0,0 +1,23 @@
+class GekanatorQuestion < ApplicationRecord
+  KINDS = ['tag', 'source', 'title', 'original_date', 'post_similarity'].freeze
+  SOURCES = ['user_suggested', 'ai_generated', 'admin_curated'].freeze
+  STATUSES = ['pending', 'accepted', 'rejected', 'disabled'].freeze
+
+  belongs_to :gekanator_question_suggestion, optional: true
+  belongs_to :created_by, class_name: 'User', optional: true
+  has_many :gekanator_question_examples, dependent: :delete_all
+
+  validates :kind, presence: true, inclusion: { in: KINDS }
+  validates :source, presence: true, inclusion: { in: SOURCES }
+  validates :status, presence: true, inclusion: { in: STATUSES }
+  validates :text, presence: true, length: { maximum: 1000 }
+  validates :condition, presence: true
+  validates :priority_weight,
+            presence: true,
+            numericality: {
+              greater_than: 0,
+              less_than_or_equal_to: 3
+            }
+
+  scope :accepted, -> { where(status: 'accepted') }
+end

backend/app/models/gekanator_question_example.rb

@@ -0,0 +1,97 @@
+class GekanatorQuestionExample < ApplicationRecord
+  ANSWERS = GekanatorQuestionSuggestion::ANSWERS
+  NON_UNKNOWN_ANSWERS = ANSWERS - ['unknown']
+  SOURCES = ['initial_suggestion', 'post_game_answer', 'post_game_extra'].freeze
+
+  belongs_to :gekanator_question
+  belongs_to :post
+  belongs_to :user
+  belongs_to :gekanator_game, optional: true
+
+  validates :answer, presence: true, inclusion: { in: ANSWERS }
+  validates :answer_counts, presence: true
+  validates :sample_count,
+            presence: true,
+            numericality: {
+              only_integer: true,
+              greater_than: 0
+            }
+  validates :source, presence: true, inclusion: { in: SOURCES }
+  validates :weight,
+            presence: true,
+            numericality: {
+              greater_than: 0
+            }
+
+  before_validation :normalize_learning_state
+
+  def record_answer!(answer:, source:, gekanator_game: nil)
+    answer = answer.to_s
+    raise ArgumentError, 'invalid answer' unless ANSWERS.include?(answer)
+
+    counts = normalized_answer_counts
+    counts[answer] += 1
+
+    self.answer_counts = counts
+    self.sample_count = counts.values.sum
+    self.gekanator_game = gekanator_game if gekanator_game.present?
+    self.source = source
+
+    apply_aggregated_answer!(preferred_answer: answer)
+    self
+  end
+
+  private
+
+  def normalize_learning_state
+    counts = normalized_answer_counts
+
+    if counts.values.sum.zero? && answer.present?
+      counts[answer] = 1
+    end
+
+    self.answer_counts = counts
+    self.sample_count = counts.values.sum
+
+    apply_aggregated_answer!
+  end
+
+  def apply_aggregated_answer!(preferred_answer: nil)
+    counts = normalized_answer_counts
+    known_counts = counts.slice(*NON_UNKNOWN_ANSWERS)
+    known_total = known_counts.values.sum
+
+    if known_total.zero?
+      self.answer = 'unknown'
+      self.weight = 0.1
+      return
+    else
+      max_count = known_counts.values.max
+      candidates = known_counts.select { |_answer, count| count == max_count }.keys
+      self.answer =
+          if preferred_answer.present? && candidates.include?(preferred_answer)
+            preferred_answer
+          elsif answer.present? && candidates.include?(answer)
+            answer
+          else
+            candidates.first
+          end
+    end
+
+    consensus = max_count.to_f / known_total
+    self.weight = Math.sqrt(known_total) * consensus
+  end
+
+  def normalized_answer_counts
+    base = ANSWERS.index_with(0)
+
+    answer_counts.to_h.each do |key, value|
+      answer_key = key.to_s
+      next unless ANSWERS.include?(answer_key)
+
+      base[answer_key] = value.to_i
+    end
+
+    base
+  end
+end

backend/app/models/gekanator_question_suggestion.rb

@@ -0,0 +1,12 @@
+class GekanatorQuestionSuggestion < ApplicationRecord
+  ANSWERS = ['yes', 'no', 'partial', 'probably_no', 'unknown'].freeze
+
+  belongs_to :gekanator_game
+  belongs_to :user
+  has_many :gekanator_questions, dependent: :nullify
+  has_many :gekanator_ai_runs, dependent: :destroy
+
+  validates :question_text, presence: true, length: { maximum: 1000 }
+  validates :answer, presence: true, inclusion: { in: ANSWERS }
+  validates :processed, inclusion: { in: [true, false] }
+end

backend/app/models/material.rb

@@ -9,6 +9,10 @@ class Material < ApplicationRecord
   belongs_to :tag, optional: true
   belongs_to :created_by_user, class_name: 'User', optional: true
   belongs_to :updated_by_user, class_name: 'User', optional: true
+  belongs_to :file_suppressed_by_user, class_name: 'User', optional: true
+
+  has_many :material_versions, dependent: :destroy
+  has_many :material_export_items, dependent: :destroy
 
   has_one_attached :file, dependent: :purge
 
@@ -18,11 +22,18 @@ class Material < ApplicationRecord
   validate :tag_must_be_material_category
 
   def content_type
+    return nil if file_suppressed?
     return nil unless file&.attached?
 
     file.blob.content_type
   end
 
+  def file_suppressed? = file_suppressed_at.present?
+
+  def snapshot_export_paths
+    material_export_items.order(:profile).pluck(:profile, :export_path).to_h
+  end
+
   private
 
   def file_must_be_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_version.rb

@@ -0,0 +1,18 @@
+class MaterialVersion < ApplicationRecord
+  EVENT_TYPE_MAP = { create: 'create',
+                     update: 'update',
+                     discard: 'discard',
+                     restore: 'restore',
+                     suppress: 'suppress' }.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

@@ -7,10 +7,23 @@ 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
   has_many :post_versions
+  has_many :gekanator_guessed_games,
+           class_name: 'GekanatorGame',
+           foreign_key: :guessed_post_id,
+           dependent: :delete_all,
+           inverse_of: :guessed_post
+  has_many :gekanator_correct_games,
+           class_name: 'GekanatorGame',
+           foreign_key: :correct_post_id,
+           dependent: :delete_all,
+           inverse_of: :correct_post
+  has_many :gekanator_question_examples, dependent: :delete_all
 
   has_many :parent_post_implications,
            class_name: 'PostImplication',

backend/app/models/tag.rb

@@ -8,6 +8,15 @@ 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
+
   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 +67,7 @@ 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 }
 
@@ -77,11 +87,13 @@ 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
 
-  def has_deerjikists = deerjikists.present?
+  def has_deerjikists = deerjikists.loaded? ? deerjikists.any? : deerjikists.exists?
 
   def self.tagme = find_or_create_by_tag_name!('タグ希望', category: :meta)
   def self.bot = find_or_create_by_tag_name!('bot操作', category: :meta)
@@ -92,7 +104,8 @@ 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
     if deny_nico && tag_names.any? { |n| n.downcase.start_with?('nico:') }
       raise NicoTagNormalisationError
     end
@@ -101,6 +114,10 @@ class Tag < ApplicationRecord
       pf, cat = CATEGORY_PREFIXES.find { |p, _| name.downcase.start_with?(p) } || ['', nil]
       name = TagName.canonicalise(name.sub(/\A#{ pf }/i, '')).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
       end
     end
@@ -228,4 +245,10 @@ 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 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/theatre.rb

@@ -7,6 +7,10 @@ class Theatre < ApplicationRecord
            class_name: 'TheatreWatchingUser', inverse_of: :theatre
   has_many :watching_users, through: :active_theatre_watching_users, source: :user
 
+  has_many :programmes, class_name: 'TheatreProgramme'
+  has_many :skip_votes, class_name: 'TheatreSkipVote', dependent: :delete_all
+  has_many :skip_events, class_name: 'TheatreSkipEvent', dependent: :delete_all
+
   belongs_to :host_user, class_name: 'User', optional: true
   belongs_to :current_post, class_name: 'Post', optional: true
   belongs_to :created_by_user, class_name: 'User'

backend/app/models/theatre_programme.rb

@@ -0,0 +1,6 @@
+class TheatreProgramme < ApplicationRecord
+  self.primary_key = :theatre_id, :position
+
+  belongs_to :theatre
+  belongs_to :post
+end

backend/app/models/theatre_skip_event.rb

@@ -0,0 +1,10 @@
+class TheatreSkipEvent < ApplicationRecord
+  belongs_to :theatre
+  belongs_to :post
+  belongs_to :skipped_by_user, class_name: 'User'
+
+  has_many :voters, class_name: 'TheatreSkipEventVoter', dependent: :delete_all
+  has_many :event_tags, class_name: 'TheatreSkipEventTag', dependent: :delete_all
+  has_many :users, through: :voters
+  has_many :tags, through: :event_tags
+end

backend/app/models/theatre_skip_event_tag.rb

@@ -0,0 +1,6 @@
+class TheatreSkipEventTag < ApplicationRecord
+  self.primary_key = :theatre_skip_event_id, :tag_id
+
+  belongs_to :theatre_skip_event
+  belongs_to :tag
+end

backend/app/models/theatre_skip_event_voter.rb

@@ -0,0 +1,6 @@
+class TheatreSkipEventVoter < ApplicationRecord
+  self.primary_key = :theatre_skip_event_id, :user_id
+
+  belongs_to :theatre_skip_event
+  belongs_to :user
+end

backend/app/models/theatre_skip_vote.rb

@@ -0,0 +1,7 @@
+class TheatreSkipVote < ApplicationRecord
+  self.primary_key = :theatre_id, :post_id, :user_id
+
+  belongs_to :theatre
+  belongs_to :post
+  belongs_to :user
+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 +2,8 @@
 
 
 module MaterialRepr
-  BASE = { only: [:id, :url, :created_at, :updated_at],
+  BASE = { only: [:id, :url, :version_no, :file_suppressed_at,
+                  :file_suppression_reason, :created_at, :updated_at],
            methods: [:content_type],
            include: { tag: TagRepr::BASE,
                       created_by_user: UserRepr::BASE,
@@ -12,13 +13,30 @@ module MaterialRepr
 
   def base material, host:
     material.as_json(BASE).merge(
-        file: if material.file.attached?
+        file: if material.file.attached? && !material.file_suppressed?
                 Rails.application.routes.url_helpers.rails_storage_proxy_url(
                     material.file, host:)
-              end)
+              end,
+        export_paths: export_paths(material),
+        export_items: export_items(material))
   end
 
   def many materials, host:
     materials.map { |m| base(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
 end

backend/app/representations/post_repr.rb

@@ -53,7 +53,7 @@ module PostRepr
   end
 
   def tag_json tags
-    tags.map { |tag| TagRepr.inline(tag) }
+    tags.reject(&:deprecated?).map { |tag| TagRepr.inline(tag) }
   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/gekanator/ai_run_budget.rb

@@ -0,0 +1,22 @@
+module Gekanator
+  class AiRunBudget
+    MONTHLY_LIMIT_JPY = BigDecimal('450').freeze
+    MAX_RUN_ESTIMATED_COST_JPY = BigDecimal('5').freeze
+
+    def self.remaining_monthly_budget_jpy
+      MONTHLY_LIMIT_JPY - monthly_cost_jpy
+    end
+
+    def self.monthly_cost_jpy
+      GekanatorAiRun.this_month.sum(:estimated_cost_jpy)
+    end
+
+    def self.exceeded?
+      monthly_cost_jpy >= MONTHLY_LIMIT_JPY
+    end
+
+    def self.exceeded_after_next_run?
+      monthly_cost_jpy + MAX_RUN_ESTIMATED_COST_JPY >= MONTHLY_LIMIT_JPY
+    end
+  end
+end

backend/app/services/gekanator/question_suggestion_ai_converter.rb

@@ -0,0 +1,168 @@
+module Gekanator
+  class QuestionSuggestionAiConverter
+    # Temporary heuristic converter for #361.
+    # This creates pending ai_generated questions without external LLM calls;
+    # accepted questions are still distributed only after admin approval.
+    TITLE_LENGTH_RE = /\Aタイトルは\s*(\d+)\s*文字以上[？?]\z/
+    ORIGINAL_YEAR_RE = /\Aオリジナルの投稿年は\s*(\d{4})\s*年[？?]\z/
+    ORIGINAL_MONTH_RE = /\Aオリジナルの投稿月は\s*(\d{1,2})\s*月[？?]\z/
+    ORIGINAL_MONTH_DAY_RE = /\Aオリジナルの投稿日は\s*(\d{1,2})\s*月\s*(\d{1,2})\s*日[？?]\z/
+    TITLE_CONTAINS_RE = /\A題名に「(.+?)」が含まれる[？?]\z/
+    SOURCE_RE = /\A(.+?)\s+の投稿を思[ひい]浮かべて[ゐい]る[？?]\z/
+
+    def self.call(...) = new(...).call
+
+    def initialize suggestion:, user:
+      @suggestion = suggestion
+      @user = user
+    end
+
+    def call
+      suggestion.with_lock do
+        existing = existing_generated_question
+        return existing if existing
+
+        run = suggestion.gekanator_ai_runs.create!(
+            model: 'heuristic_converter_v1',
+            status: 'running',
+            input_tokens: 0,
+            output_tokens: 0,
+            estimated_cost_jpy: 0)
+
+        question_attributes = build_question
+        question =
+            question_attributes &&
+            GekanatorQuestion.create!(
+                **question_attributes,
+                source: 'ai_generated',
+                status: 'pending',
+                gekanator_question_suggestion: suggestion,
+                created_by: user)
+
+        run.update!(status: question ? 'succeeded' : 'failed')
+        question
+      end
+    rescue => error
+      run&.update!(status: 'failed') if run&.persisted? && run.status != 'failed'
+      raise error
+    end
+
+    private
+
+    attr_reader :suggestion, :user
+
+    def existing_generated_question
+      suggestion
+          .gekanator_questions
+          .where(source: 'ai_generated')
+          .order(id: :desc)
+          .first
+    end
+
+    def build_question
+      text = normalized_text
+      return nil if text.blank?
+
+      structured_question_for(text) || post_similarity_question_for(text)
+    end
+
+    def normalized_text
+      suggestion.question_text.to_s.gsub(/[[:space:]]+/, ' ').strip
+    end
+
+    def structured_question_for text
+      case text
+      when TITLE_LENGTH_RE
+        length = Regexp.last_match(1).to_i
+        return nil if length <= 0
+
+        {
+          text:,
+          kind: 'title',
+          condition: {
+            type: 'title-length-at-least',
+            length:
+          },
+          priority_weight: 0.95
+        }
+      when /\A題名に英数字が混じって[ゐい]る[？?]\z/
+        {
+          text: '題名に英数字が混じってゐる?',
+          kind: 'title',
+          condition: { type: 'title-has-ascii' },
+          priority_weight: 0.95
+        }
+      when ORIGINAL_YEAR_RE
+        year = Regexp.last_match(1).to_i
+        {
+          text:,
+          kind: 'original_date',
+          condition: { type: 'original-year', year: },
+          priority_weight: 0.95
+        }
+      when ORIGINAL_MONTH_RE
+        month = Regexp.last_match(1).to_i
+        return nil unless month.between?(1, 12)
+
+        {
+          text:,
+          kind: 'original_date',
+          condition: { type: 'original-month', month: },
+          priority_weight: 0.95
+        }
+      when ORIGINAL_MONTH_DAY_RE
+        month = Regexp.last_match(1).to_i
+        day = Regexp.last_match(2).to_i
+        return nil unless month.between?(1, 12) && day.between?(1, 31)
+
+        {
+          text:,
+          kind: 'original_date',
+          condition: {
+            type: 'original-month-day',
+            monthDay: "#{ month }-#{ day }"
+          },
+          priority_weight: 0.95
+        }
+      when TITLE_CONTAINS_RE
+        title_text = Regexp.last_match(1).to_s.strip
+        return nil if title_text.blank?
+
+        {
+          text: "題名に「#{ title_text }」が含まれる?",
+          kind: 'title',
+          condition: { type: 'title-contains', text: title_text },
+          priority_weight: 0.95
+        }
+      when SOURCE_RE
+        host = Regexp.last_match(1).to_s.strip
+        return nil if host.blank?
+
+        {
+          text:,
+          kind: 'source',
+          condition: { type: 'source', host: },
+          priority_weight: 0.95
+        }
+      else
+        nil
+      end
+    end
+
+    def post_similarity_question_for text
+      return nil if suggestion.answer == 'unknown'
+
+      {
+        text:,
+        kind: 'post_similarity',
+        condition: {
+          type: 'post-similarity',
+          postId: suggestion.gekanator_game.correct_post_id,
+          answer: suggestion.answer,
+          threshold: 0.65
+        },
+        priority_weight: 1.0
+      }
+    end
+  end
+end

backend/app/services/gekanator/question_suggestion_promoter.rb

@@ -0,0 +1,52 @@
+module Gekanator
+  class QuestionSuggestionPromoter
+    def self.call(...) = new(...).call
+
+    def initialize suggestion:, user:
+      @suggestion = suggestion
+      @user = user
+    end
+
+    def call
+      suggestion.with_lock do
+        return promoted_question if suggestion.processed?
+        return suggestion if suggestion.answer == 'unknown'
+
+        question = GekanatorQuestion.create!(
+            text: suggestion.question_text,
+            kind: 'post_similarity',
+            source: 'user_suggested',
+            status: 'accepted',
+            priority_weight: 1.2,
+            condition: {
+              type: 'post-similarity',
+              postId: suggestion.gekanator_game.correct_post_id,
+              answer: suggestion.answer,
+              threshold: 0.65
+            },
+            gekanator_question_suggestion: suggestion,
+            created_by: user)
+        example =
+            GekanatorQuestionExample.new(
+                gekanator_question: question,
+                post: suggestion.gekanator_game.correct_post,
+                user: user)
+        example.record_answer!(
+            answer: suggestion.answer,
+            source: 'initial_suggestion',
+            gekanator_game: suggestion.gekanator_game)
+        example.save!
+        suggestion.update!(processed: true)
+        question
+      end
+    end
+
+    private
+
+    attr_reader :suggestion, :user
+
+    def promoted_question
+      suggestion.gekanator_questions.order(id: :desc).first
+    end
+  end
+end

backend/app/services/material_file_sha256.rb

@@ -0,0 +1,34 @@
+require 'digest'
+
+class MaterialFileSha256
+  def self.from_blob blob, allow_download: false
+    sha256 = blob.metadata['sha256']
+    return sha256 if sha256.present?
+    return nil unless allow_download
+
+    begin
+      blob.open do |file|
+        sha256 = Digest::SHA256.file(file.path).hexdigest
+        blob.metadata['sha256'] = sha256
+        blob.save! if blob.changed?
+        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_version_recorder.rb

@@ -0,0 +1,70 @@
+class MaterialVersionRecorder < VersionRecorder
+  EVENT_TYPES = ['create', 'update', 'discard', 'restore', 'suppress'].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,
+      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],
+      file_suppressed_at: @record.file_suppressed_at,
+      file_suppression_reason: @record.file_suppression_reason }
+  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: blob.metadata['sha256'] }
+  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 +1,149 @@
+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)
+           .where(materials: { file_suppressed_at: nil })
+           .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/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/theatre_post_advancer.rb

@@ -0,0 +1,29 @@
+class TheatrePostAdvancer
+  def self.call(theatre:)
+    new(theatre:).call
+  end
+
+  def initialize(theatre:)
+    @theatre = theatre
+  end
+
+  def call
+    previous_post = theatre.current_post
+    post = TheatrePostSelector.new(theatre:).select
+
+    TheatreSkipVote.where(theatre:, post: previous_post).delete_all if previous_post
+
+    theatre.update!(current_post: post, current_post_started_at: post ? Time.current : nil)
+
+    if post
+      position = (theatre.programmes.maximum(:position) || 0) + 1
+      theatre.programmes.create!(position:, post:)
+    end
+
+    post
+  end
+
+  private
+
+  attr_reader :theatre
+end

backend/app/services/theatre_post_selector.rb

@@ -0,0 +1,119 @@
+class TheatrePostSelector
+  Candidate = Struct.new(:post, :weight, :penalty, :tags, keyword_init: true)
+  ELIGIBLE_POST_URL_CONDITION =
+      ["url LIKE '%nicovideo.jp%'",
+       "url LIKE '%youtube.com/watch%'",
+       "url LIKE '%youtu.be/%'"]
+      .join(' OR ')
+
+  def initialize theatre:
+    @theatre = theatre
+  end
+
+  def select
+    candidates = weighted_candidates
+    return nil if candidates.empty?
+
+    total = candidates.sum(&:weight)
+    target = rand * total
+
+    candidates.each do |candidate|
+      target -= candidate.weight
+      return candidate.post if target <= 0
+    end
+
+    candidates.last.post
+  end
+
+  def weight_json limit: 20
+    candidates = weighted_candidates
+    sorted = candidates.sort_by { |candidate| [candidate.weight, candidate.post.id] }
+
+    { tag_penalties: tag_penalty_json,
+      lightest_posts: post_weight_json(sorted.first(limit)),
+      heaviest_posts: post_weight_json(sorted.reverse.first(limit)) }
+  end
+
+  private
+
+  attr_reader :theatre
+
+  def weighted_candidates
+    @weighted_candidates ||= begin
+      penalties = tag_penalties
+      posts = eligible_posts.includes(tags: :tag_name).to_a
+
+      posts.map do |post|
+        post_tags = post.tags.to_a
+        penalty = post_tags.sum { |tag| penalties[tag.id].to_i }
+
+        Candidate.new(
+            post:,
+            penalty:,
+            tags: post_tags,
+            weight: 1.0 / (1.0 + penalty))
+      end
+    end
+  end
+
+  def eligible_posts
+    posts = Post.where(ELIGIBLE_POST_URL_CONDITION)
+    posts = posts.where.not(id: theatre.current_post_id) if theatre.current_post_id
+    posts
+  end
+
+  def active_user_ids
+    @active_user_ids ||= theatre.watching_users.ids
+  end
+
+  def tag_penalties
+    @tag_penalties ||=
+      if active_user_ids.empty?
+        {}
+      else
+        TheatreSkipEventVoter
+          .joins(theatre_skip_event: :event_tags)
+          .where(user_id: active_user_ids)
+          .group('theatre_skip_event_tags.tag_id')
+          .count
+      end
+  end
+
+  def tag_penalty_json
+    return [] if tag_penalties.empty?
+
+    tags = Tag.where(id: tag_penalties.keys).includes(:tag_name).index_by(&:id)
+
+    tag_penalties
+      .map { |tag_id, penalty|
+        tag = tags[tag_id]
+        next unless tag
+
+        { tag: light_tag_json(tag),
+          penalty: }
+      }
+      .compact
+      .sort_by { |row| [-row[:penalty], row[:tag][:name].to_s] }
+  end
+
+  def post_weight_json candidates
+    candidates.map { |candidate|
+      { post: light_post_json(candidate.post),
+        weight: candidate.weight,
+        penalty: candidate.penalty,
+        tags: candidate.tags.map { |tag| light_tag_json(tag) } }
+    }
+  end
+
+  def light_post_json post
+    { id: post.id,
+      title: post.title,
+      url: post.url }
+  end
+
+  def light_tag_json tag
+    { id: tag.id,
+      name: tag.name,
+      category: tag.category }
+  end
+end

backend/app/services/theatre_skip_finalizer.rb

@@ -0,0 +1,40 @@
+class TheatreSkipFinalizer
+  def self.call(theatre:, user:)
+    new(theatre:, user:).call
+  end
+
+  def initialize(theatre:, user:)
+    @theatre = theatre
+    @user = user
+  end
+
+  def call
+    return unless theatre.current_post
+
+    post = theatre.current_post
+    voters = TheatreSkipVote.where(theatre:, post:).includes(:user).map(&:user)
+    return if voters.empty?
+
+    event = TheatreSkipEvent.create!(
+        theatre:,
+        post:,
+        skipped_by_user: user,
+        programme_position: theatre.programmes.maximum(:position))
+
+    voters.uniq(&:id).each do |voter|
+      TheatreSkipEventVoter.create!(theatre_skip_event: event, user: voter)
+    end
+
+    post.tags.find_each do |tag|
+      TheatreSkipEventTag.create!(theatre_skip_event: event, tag:)
+    end
+
+    TheatreSkipVote.where(theatre:, post:).delete_all
+
+    event
+  end
+
+  private
+
+  attr_reader :theatre, :user
+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

@@ -63,6 +63,24 @@ Rails.application.routes.draw do
     end
   end
 
+  namespace :gekanator do
+    resources :games, only: [:create], controller: '/gekanator_games' do
+      member do
+        get :extra_questions
+        post :extra_question_answers
+      end
+    end
+    resources :posts, only: [:index], controller: '/gekanator_posts'
+    resources :questions, only: [:index], controller: '/gekanator_questions'
+    resources :question_suggestions,
+              only: [:create],
+              controller: '/gekanator_question_suggestions' do
+      member do
+        post :ai_convert
+      end
+    end
+  end
+
   resources :users, only: [:create, :update] do
     collection do
       post :verify
@@ -85,10 +103,20 @@ Rails.application.routes.draw do
     member do
       put :watching
       patch :next_post
+      put :skip_vote
+      delete :skip_vote, action: :unskip_vote
+      get :post_selection_weights
     end
 
-    resources :comments, controller: :theatre_comments, only: [:index, :create]
+    resources :comments, controller: :theatre_comments, only: [:index, :create, :destroy]
+    resources :programmes, controller: :theatre_programmes, only: [:index]
+    resources :skip_events, controller: :theatre_skip_events, only: [:index]
   end
 
-  resources :materials, only: [:index, :show, :create, :update, :destroy]
+  get 'materials/download.zip', to: 'materials#download'
+  resources :materials, only: [:index, :show, :create, :update, :destroy] do
+    member do
+      patch :suppress_file
+    end
+  end
 end

backend/db/migrate/20260514221900_create_theatre_programmes.rb

@@ -0,0 +1,10 @@
+class CreateTheatreProgrammes < ActiveRecord::Migration[8.0]
+  def change
+    create_table :theatre_programmes, primary_key: [:theatre_id, :position] do |t|
+      t.references :theatre, null: false, foreign_key: true
+      t.integer :position, null: false
+      t.references :post, null: false, foreign_key: true
+      t.datetime :created_at, null: false
+    end
+  end
+end

backend/db/migrate/20260606000000_create_theatre_skip_votes_and_events.rb

@@ -0,0 +1,36 @@
+class CreateTheatreSkipVotesAndEvents < ActiveRecord::Migration[8.0]
+  def change
+    create_table :theatre_skip_votes, primary_key: [:theatre_id, :post_id, :user_id] do |t|
+      t.references :theatre, null: false, foreign_key: true
+      t.references :post, null: false, foreign_key: true
+      t.references :user, null: false, foreign_key: true
+      t.timestamps
+    end
+
+    create_table :theatre_skip_events do |t|
+      t.references :theatre, null: false, foreign_key: true
+      t.references :post, null: false, foreign_key: true
+      t.references :skipped_by_user, null: false, foreign_key: { to_table: :users }
+      t.integer :programme_position
+      t.datetime :created_at, null: false
+    end
+
+    create_table :theatre_skip_event_voters, primary_key: [:theatre_skip_event_id, :user_id] do |t|
+      t.references :theatre_skip_event, null: false, foreign_key: true
+      t.references :user, null: false, foreign_key: true
+    end
+
+    create_table :theatre_skip_event_tags, primary_key: [:theatre_skip_event_id, :tag_id] do |t|
+      t.references :theatre_skip_event, null: false, foreign_key: true
+      t.references :tag, null: false, foreign_key: true
+    end
+
+    add_index :theatre_skip_events, [:theatre_id, :created_at]
+    add_index :theatre_skip_votes, [:theatre_id, :post_id, :created_at],
+              name: 'idx_theatre_skip_votes_theatre_post_created'
+    add_index :theatre_skip_event_voters, [:user_id, :theatre_skip_event_id],
+              name: 'idx_theatre_skip_event_voters_user_event'
+    add_index :theatre_skip_event_tags, [:tag_id, :theatre_skip_event_id],
+              name: 'idx_theatre_skip_event_tags_tag_event'
+  end
+end

backend/db/migrate/20260607000000_create_gekanator_games.rb

@@ -0,0 +1,18 @@
+class CreateGekanatorGames < ActiveRecord::Migration[8.0]
+  def change
+    create_table :gekanator_games do |t|
+      t.references :user, null: false, foreign_key: true
+      t.references :guessed_post, null: false, foreign_key: { to_table: :posts }
+      t.references :correct_post, null: false, foreign_key: { to_table: :posts }
+      t.boolean :won, null: false
+      t.integer :question_count, null: false
+      t.json :answers, null: false
+
+      t.timestamps
+    end
+
+    add_check_constraint :gekanator_games,
+                         'question_count >= 0',
+                         name: 'chk_gekanator_games_question_count_nonnegative'
+  end
+end

backend/db/migrate/20260608000000_create_gekanator_question_suggestions.rb

@@ -0,0 +1,14 @@
+class CreateGekanatorQuestionSuggestions < ActiveRecord::Migration[8.0]
+  def change
+    create_table :gekanator_question_suggestions do |t|
+      t.references :gekanator_game,
+                   null: false,
+                   foreign_key: { on_delete: :cascade }
+      t.references :user, null: false, foreign_key: true
+      t.text :question_text, null: false
+      t.boolean :processed, null: false, default: false
+
+      t.timestamps
+    end
+  end
+end

backend/db/migrate/20260608002000_add_answer_to_gekanator_question_suggestions.rb

@@ -0,0 +1,5 @@
+class AddAnswerToGekanatorQuestionSuggestions < ActiveRecord::Migration[8.0]
+  def change
+    add_column :gekanator_question_suggestions, :answer, :string, null: false
+  end
+end

backend/db/migrate/20260609000000_create_gekanator_questions.rb

@@ -0,0 +1,19 @@
+class CreateGekanatorQuestions < ActiveRecord::Migration[8.0]
+  def change
+    create_table :gekanator_questions do |t|
+      t.string :text, null: false
+      t.string :kind, null: false
+      t.json :condition, null: false
+      t.string :source, null: false, default: 'ai_generated'
+      t.string :status, null: false, default: 'pending'
+      t.float :priority_weight, null: false, default: 1.0
+      t.references :gekanator_question_suggestion,
+                   null: true,
+                   foreign_key: true
+      t.references :created_by,
+                   null: true,
+                   foreign_key: { to_table: :users }
+      t.timestamps
+    end
+  end
+end

backend/db/migrate/20260609001000_create_gekanator_ai_runs.rb

@@ -0,0 +1,13 @@
+class CreateGekanatorAiRuns < ActiveRecord::Migration[8.0]
+  def change
+    create_table :gekanator_ai_runs do |t|
+      t.string :model, null: false
+      t.integer :input_tokens, null: false, default: 0
+      t.integer :output_tokens, null: false, default: 0
+      t.decimal :estimated_cost_jpy, precision: 8, scale: 3, null: false, default: 0
+      t.string :status, null: false, default: 'pending'
+      t.references :gekanator_question_suggestion, null: false, foreign_key: true
+      t.timestamps
+    end
+  end
+end

backend/db/migrate/20260610000000_create_gekanator_question_examples.rb

@@ -0,0 +1,19 @@
+class CreateGekanatorQuestionExamples < ActiveRecord::Migration[8.0]
+  def change
+    create_table :gekanator_question_examples do |t|
+      t.references :gekanator_question, null: false, foreign_key: true
+      t.references :post, null: false, foreign_key: true
+      t.references :user, null: false, foreign_key: true
+      t.references :gekanator_game, null: true, foreign_key: true
+      t.string :answer, null: false
+      t.string :source, null: false, default: 'post_game_extra'
+      t.float :weight, null: false, default: 1.0
+      t.timestamps
+    end
+
+    add_index :gekanator_question_examples,
+              [:gekanator_question_id, :post_id, :user_id],
+              unique: true,
+              name: 'idx_gekanator_question_examples_on_question_post_user'
+  end
+end

backend/db/migrate/20260612000000_add_answer_statistics_to_gekanator_question_examples.rb

@@ -0,0 +1,40 @@
+class AddAnswerStatisticsToGekanatorQuestionExamples < ActiveRecord::Migration[8.0]
+  class MigrationGekanatorQuestionExample < ApplicationRecord
+    self.table_name = 'gekanator_question_examples'
+  end
+
+  def up
+    add_column :gekanator_question_examples,
+               :answer_counts,
+               :json,
+               null: true
+    add_column :gekanator_question_examples,
+               :sample_count,
+               :integer,
+               null: false,
+               default: 1
+
+    MigrationGekanatorQuestionExample.reset_column_information
+    MigrationGekanatorQuestionExample.find_each do |example|
+      counts = {
+        'yes' => 0,
+        'no' => 0,
+        'partial' => 0,
+        'probably_no' => 0,
+        'unknown' => 0
+      }
+      counts[example.answer] = 1 if counts.key?(example.answer)
+
+      example.update_columns(
+        answer_counts: counts,
+        sample_count: 1)
+    end
+
+    change_column_null :gekanator_question_examples, :answer_counts, false
+  end
+
+  def down
+    remove_column :gekanator_question_examples, :sample_count
+    remove_column :gekanator_question_examples, :answer_counts
+  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/20260623000000_enhance_material_management.rb

@@ -0,0 +1,98 @@
+class EnhanceMaterialManagement < ActiveRecord::Migration[8.0]
+  def up
+    change_table :materials, bulk: true do |t|
+      t.integer :version_no, null: false, default: 1
+      t.datetime :file_suppressed_at
+      t.references :file_suppressed_by_user, foreign_key: { to_table: :users }
+      t.string :file_suppression_reason
+    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
+      t.datetime :file_suppressed_at
+      t.string :file_suppression_reason
+    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', 'suppress')",
+                         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 :material_versions, :file_suppressed_at
+    remove_column :material_versions, :file_suppression_reason
+
+    remove_reference :materials, :file_suppressed_by_user, foreign_key: { to_table: :users }
+    remove_column :materials, :version_no
+    remove_column :materials, :file_suppressed_at
+    remove_column :materials, :file_suppression_reason
+  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_05_07_213300) do
+ActiveRecord::Schema[8.0].define(version: 2026_06_23_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
@@ -48,6 +48,79 @@ ActiveRecord::Schema[8.0].define(version: 2026_05_07_213300) do
     t.index ["tag_id"], name: "index_deerjikists_on_tag_id"
   end
 
+  create_table "gekanator_ai_runs", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "model", null: false
+    t.integer "input_tokens", default: 0, null: false
+    t.integer "output_tokens", default: 0, null: false
+    t.decimal "estimated_cost_jpy", precision: 8, scale: 3, default: "0.0", null: false
+    t.string "status", default: "pending", null: false
+    t.bigint "gekanator_question_suggestion_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["gekanator_question_suggestion_id"], name: "index_gekanator_ai_runs_on_gekanator_question_suggestion_id"
+  end
+
+  create_table "gekanator_games", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "user_id", null: false
+    t.bigint "guessed_post_id", null: false
+    t.bigint "correct_post_id", null: false
+    t.boolean "won", null: false
+    t.integer "question_count", null: false
+    t.json "answers", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["correct_post_id"], name: "index_gekanator_games_on_correct_post_id"
+    t.index ["guessed_post_id"], name: "index_gekanator_games_on_guessed_post_id"
+    t.index ["user_id"], name: "index_gekanator_games_on_user_id"
+    t.check_constraint "`question_count` >= 0", name: "chk_gekanator_games_question_count_nonnegative"
+  end
+
+  create_table "gekanator_question_examples", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "gekanator_question_id", null: false
+    t.bigint "post_id", null: false
+    t.bigint "user_id", null: false
+    t.bigint "gekanator_game_id"
+    t.string "answer", null: false
+    t.string "source", default: "post_game_extra", null: false
+    t.float "weight", default: 1.0, null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.json "answer_counts", null: false
+    t.integer "sample_count", default: 1, null: false
+    t.index ["gekanator_game_id"], name: "index_gekanator_question_examples_on_gekanator_game_id"
+    t.index ["gekanator_question_id", "post_id", "user_id"], name: "idx_gekanator_question_examples_on_question_post_user", unique: true
+    t.index ["gekanator_question_id"], name: "index_gekanator_question_examples_on_gekanator_question_id"
+    t.index ["post_id"], name: "index_gekanator_question_examples_on_post_id"
+    t.index ["user_id"], name: "index_gekanator_question_examples_on_user_id"
+  end
+
+  create_table "gekanator_question_suggestions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "gekanator_game_id", null: false
+    t.bigint "user_id", null: false
+    t.text "question_text", null: false
+    t.boolean "processed", default: false, null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.string "answer", null: false
+    t.index ["gekanator_game_id"], name: "index_gekanator_question_suggestions_on_gekanator_game_id"
+    t.index ["user_id"], name: "index_gekanator_question_suggestions_on_user_id"
+  end
+
+  create_table "gekanator_questions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "text", null: false
+    t.string "kind", null: false
+    t.json "condition", null: false
+    t.string "source", default: "ai_generated", null: false
+    t.string "status", default: "pending", null: false
+    t.float "priority_weight", default: 1.0, null: false
+    t.bigint "gekanator_question_suggestion_id"
+    t.bigint "created_by_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["created_by_id"], name: "index_gekanator_questions_on_created_by_id"
+    t.index ["gekanator_question_suggestion_id"], name: "index_gekanator_questions_on_gekanator_question_suggestion_id"
+  end
+
   create_table "ip_addresses", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.binary "ip_address", limit: 16, null: false
     t.datetime "banned_at"
@@ -57,6 +130,32 @@ ActiveRecord::Schema[8.0].define(version: 2026_05_07_213300) 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_versions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "material_id", null: false
     t.integer "version_no", null: false
@@ -68,14 +167,28 @@ ActiveRecord::Schema[8.0].define(version: 2026_05_07_213300) 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.datetime "file_suppressed_at"
+    t.string "file_suppression_reason"
     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',_utf8mb4'suppress')", name: "material_versions_event_type_valid"
   end
 
   create_table "materials", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
@@ -88,9 +201,14 @@ ActiveRecord::Schema[8.0].define(version: 2026_05_07_213300) 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.datetime "file_suppressed_at"
+    t.bigint "file_suppressed_by_user_id"
+    t.string "file_suppression_reason"
     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"
+    t.index ["file_suppressed_by_user_id"], name: "index_materials_on_file_suppressed_by_user_id"
     t.index ["parent_id"], name: "index_materials_on_parent_id"
     t.index ["tag_id"], name: "index_materials_on_tag_id"
     t.index ["updated_by_user_id"], name: "index_materials_on_updated_by_user_id"
@@ -246,6 +364,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_05_07_213300) do
     t.string "event_type", null: false
     t.string "name", null: false
     t.string "category", null: false
+    t.datetime "deprecated_at"
     t.text "aliases", null: false
     t.text "parent_tag_ids", null: false
     t.datetime "created_at", null: false
@@ -263,10 +382,13 @@ ActiveRecord::Schema[8.0].define(version: 2026_05_07_213300) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.integer "post_count", default: 0, null: false
+    t.datetime "deprecated_at"
     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
 
@@ -283,6 +405,55 @@ ActiveRecord::Schema[8.0].define(version: 2026_05_07_213300) do
     t.index ["user_id"], name: "index_theatre_comments_on_user_id"
   end
 
+  create_table "theatre_programmes", primary_key: ["theatre_id", "position"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "theatre_id", null: false
+    t.integer "position", null: false
+    t.bigint "post_id", null: false
+    t.datetime "created_at", null: false
+    t.index ["post_id"], name: "index_theatre_programmes_on_post_id"
+    t.index ["theatre_id"], name: "index_theatre_programmes_on_theatre_id"
+  end
+
+  create_table "theatre_skip_event_tags", primary_key: ["theatre_skip_event_id", "tag_id"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "theatre_skip_event_id", null: false
+    t.bigint "tag_id", null: false
+    t.index ["tag_id", "theatre_skip_event_id"], name: "idx_theatre_skip_event_tags_tag_event"
+    t.index ["tag_id"], name: "index_theatre_skip_event_tags_on_tag_id"
+    t.index ["theatre_skip_event_id"], name: "index_theatre_skip_event_tags_on_theatre_skip_event_id"
+  end
+
+  create_table "theatre_skip_event_voters", primary_key: ["theatre_skip_event_id", "user_id"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "theatre_skip_event_id", null: false
+    t.bigint "user_id", null: false
+    t.index ["theatre_skip_event_id"], name: "index_theatre_skip_event_voters_on_theatre_skip_event_id"
+    t.index ["user_id", "theatre_skip_event_id"], name: "idx_theatre_skip_event_voters_user_event"
+    t.index ["user_id"], name: "index_theatre_skip_event_voters_on_user_id"
+  end
+
+  create_table "theatre_skip_events", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "theatre_id", null: false
+    t.bigint "post_id", null: false
+    t.bigint "skipped_by_user_id", null: false
+    t.integer "programme_position"
+    t.datetime "created_at", null: false
+    t.index ["post_id"], name: "index_theatre_skip_events_on_post_id"
+    t.index ["skipped_by_user_id"], name: "index_theatre_skip_events_on_skipped_by_user_id"
+    t.index ["theatre_id", "created_at"], name: "index_theatre_skip_events_on_theatre_id_and_created_at"
+    t.index ["theatre_id"], name: "index_theatre_skip_events_on_theatre_id"
+  end
+
+  create_table "theatre_skip_votes", primary_key: ["theatre_id", "post_id", "user_id"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "theatre_id", null: false
+    t.bigint "post_id", null: false
+    t.bigint "user_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["post_id"], name: "index_theatre_skip_votes_on_post_id"
+    t.index ["theatre_id", "post_id", "created_at"], name: "idx_theatre_skip_votes_theatre_post_created"
+    t.index ["theatre_id"], name: "index_theatre_skip_votes_on_theatre_id"
+    t.index ["user_id"], name: "index_theatre_skip_votes_on_user_id"
+  end
+
   create_table "theatre_watching_users", primary_key: ["theatre_id", "user_id"], charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.bigint "theatre_id", null: false
     t.bigint "user_id", null: false
@@ -429,6 +600,21 @@ ActiveRecord::Schema[8.0].define(version: 2026_05_07_213300) do
 
   add_foreign_key "active_storage_attachments", "active_storage_blobs", column: "blob_id"
   add_foreign_key "active_storage_variant_records", "active_storage_blobs", column: "blob_id"
+  add_foreign_key "gekanator_ai_runs", "gekanator_question_suggestions"
+  add_foreign_key "gekanator_games", "posts", column: "correct_post_id"
+  add_foreign_key "gekanator_games", "posts", column: "guessed_post_id"
+  add_foreign_key "gekanator_games", "users"
+  add_foreign_key "gekanator_question_examples", "gekanator_games"
+  add_foreign_key "gekanator_question_examples", "gekanator_questions"
+  add_foreign_key "gekanator_question_examples", "posts"
+  add_foreign_key "gekanator_question_examples", "users"
+  add_foreign_key "gekanator_question_suggestions", "gekanator_games", on_delete: :cascade
+  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_versions", "materials"
   add_foreign_key "material_versions", "materials", column: "parent_id"
   add_foreign_key "material_versions", "tags"
@@ -437,6 +623,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_05_07_213300) do
   add_foreign_key "materials", "materials", column: "parent_id"
   add_foreign_key "materials", "tags"
   add_foreign_key "materials", "users", column: "created_by_user_id"
+  add_foreign_key "materials", "users", column: "file_suppressed_by_user_id"
   add_foreign_key "materials", "users", column: "updated_by_user_id"
   add_foreign_key "nico_tag_relations", "tags"
   add_foreign_key "nico_tag_relations", "tags", column: "nico_tag_id"
@@ -464,6 +651,18 @@ ActiveRecord::Schema[8.0].define(version: 2026_05_07_213300) do
   add_foreign_key "tags", "tag_names"
   add_foreign_key "theatre_comments", "theatres"
   add_foreign_key "theatre_comments", "users"
+  add_foreign_key "theatre_programmes", "posts"
+  add_foreign_key "theatre_programmes", "theatres"
+  add_foreign_key "theatre_skip_event_tags", "tags"
+  add_foreign_key "theatre_skip_event_tags", "theatre_skip_events"
+  add_foreign_key "theatre_skip_event_voters", "theatre_skip_events"
+  add_foreign_key "theatre_skip_event_voters", "users"
+  add_foreign_key "theatre_skip_events", "posts"
+  add_foreign_key "theatre_skip_events", "theatres"
+  add_foreign_key "theatre_skip_events", "users", column: "skipped_by_user_id"
+  add_foreign_key "theatre_skip_votes", "posts"
+  add_foreign_key "theatre_skip_votes", "theatres"
+  add_foreign_key "theatre_skip_votes", "users"
   add_foreign_key "theatre_watching_users", "theatres"
   add_foreign_key "theatre_watching_users", "users"
   add_foreign_key "theatres", "posts", column: "current_post_id"

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/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/tag_name_sanitisation_rule_spec.rb

@@ -1,6 +1,10 @@
 require 'rails_helper'
 
 RSpec.describe TagNameSanitisationRule, type: :model do
+  before do
+    described_class.unscoped.delete_all
+  end
+
   describe '.sanitise' do
     before do
       described_class.create!(priority: 10, source_pattern: '_', replacement: '')

backend/spec/models/tag_spec.rb

@@ -1,6 +1,79 @@
 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
+  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)
+      TagImplication.create!(tag: second, parent_tag: first)
+
+      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/requests/gekanator_games_spec.rb

@@ -0,0 +1,76 @@
+require 'rails_helper'
+
+RSpec.describe 'Gekanator games API', type: :request do
+  let!(:admin) { create_admin_user! }
+  let!(:user) { create_member_user! }
+  let!(:guessed_post) { Post.create!(title: 'guess', url: 'https://example.com/guess') }
+  let!(:correct_post) { Post.create!(title: 'correct', url: 'https://example.com/correct') }
+
+  describe 'POST /gekanator/games' do
+    it 'stores a won game' do
+      sign_in_as admin
+
+      post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          correct_post_id: guessed_post.id,
+          answers: [{ question_id: 'tag:1', answer: 'yes' }] }
+
+      expect(response).to have_http_status(:created)
+      game = GekanatorGame.find(json['id'])
+      expect(game.user).to eq(admin)
+      expect(game.guessed_post).to eq(guessed_post)
+      expect(game.correct_post).to eq(guessed_post)
+      expect(game.won).to eq(true)
+      expect(game.question_count).to eq(1)
+      expect(game.answers).to eq([{ 'question_id' => 'tag:1', 'answer' => 'yes' }])
+    end
+
+    it 'stores a lost game with the correct post' do
+      sign_in_as admin
+
+      post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          correct_post_id: correct_post.id,
+          question_count: 4,
+          answers: [{ question_id: 'tag:1', answer: 'no' }] }
+
+      expect(response).to have_http_status(:created)
+      game = GekanatorGame.find(json['id'])
+      expect(game.correct_post).to eq(correct_post)
+      expect(game.won).to eq(false)
+      expect(game.question_count).to eq(1)
+    end
+
+    it 'rejects a game without the correct post' do
+      sign_in_as admin
+
+      post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          question_count: 4,
+          answers: [{ question_id: 'tag:1', answer: 'no' }] }
+
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+
+    it 'returns unauthorized without a user' do
+      post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          correct_post_id: guessed_post.id,
+          answers: [] }
+
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it 'stores a game for a non-admin user' do
+      sign_in_as user
+
+      post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          correct_post_id: guessed_post.id,
+          answers: [{ question_id: 'tag:1', answer: 'yes' }] }
+
+      expect(response).to have_http_status(:created)
+      expect(GekanatorGame.find(json['id']).user).to eq(user)
+    end
+  end
+end

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
@@ -97,7 +107,9 @@ RSpec.describe 'Materials API', type: :request do
   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 +150,22 @@ 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 +187,49 @@ 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 '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 +269,33 @@ 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 +349,26 @@ 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 +379,15 @@ 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 +395,7 @@ 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 '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 +411,7 @@ 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 +419,190 @@ 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)
+
+        expect do
+          put "/materials/#{ material.id }", params: {
+            tag: 'material_update_old'
+          }
+        end.not_to change(MaterialVersion, :count)
+
+        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 suppressed materials' do
+      material_b.update!(file_suppressed_at: Time.current,
+                         file_suppression_reason: 'copyright_high_risk')
+
+      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 'PATCH /materials/:id/suppress_file' do
+    let!(:tag) do
+      Tag.create!(tag_name: TagName.create!(name: 'material_suppress'), category: :material)
+    end
+    let!(:material) do
+      build_material(tag:, user: member_user, file: dummy_upload(filename: 'suppress.png'))
+    end
+
+    it 'allows admin to suppress a file and records a suppress version' do
+      sign_in_as(admin_user)
+      MaterialVersionRecorder.record!(material:, event_type: :create,
+                                      created_by_user: member_user)
+
+      expect do
+        patch "/materials/#{ material.id }/suppress_file",
+              params: { reason: 'copyright_high_risk' }
+      end.to change(MaterialVersion, :count).by(1)
+
+      expect(response).to have_http_status(:ok)
+
+      material.reload
+      expect(material.file_suppressed_at).to be_present
+      expect(material.file_suppressed_by_user).to eq(admin_user)
+      expect(material.file_suppression_reason).to eq('copyright_high_risk')
+      expect(material.material_versions.order(:version_no).last.event_type).to eq('suppress')
+      expect(json['file']).to be_nil
+      expect(json['file_suppressed_at']).to be_present
+    end
+
+    it 'purges blob when purge=true is requested' do
+      sign_in_as(admin_user)
+      old_blob_id = material.file.blob.id
+      MaterialVersionRecorder.record!(material:, event_type: :create,
+                                      created_by_user: member_user)
+
+      expect do
+        patch "/materials/#{ material.id }/suppress_file",
+              params: { reason: 'copyright_takedown', purge: '1' }
+      end.to have_enqueued_job(ActiveStorage::PurgeJob)
+
+      expect(response).to have_http_status(:ok)
+
+      version = material.material_versions.order(:version_no).last
+      expect(version.event_type).to eq('suppress')
+      expect(version.file_blob_id).to eq(old_blob_id)
+      expect(version.file_filename).to eq('suppress.png')
+      expect(version.file_sha256).to be_present
+    end
+
+    it 'rejects member suppression' do
+      sign_in_as(member_user)
+
+      patch "/materials/#{ material.id }/suppress_file",
+            params: { reason: 'copyright_high_risk' }
+
+      expect(response).to have_http_status(:forbidden)
     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

@@ -517,6 +517,24 @@ 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!(
@@ -697,6 +715,58 @@ 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
+
     context "when nico tag already exists in tags" do
       before do
         Tag.find_undiscard_or_create_by!(
@@ -930,6 +1000,26 @@ 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/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' }
@@ -585,6 +647,111 @@ 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)
+      TagImplication.create!(tag: first, parent_tag: second)
+
+      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 +899,20 @@ 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 +930,7 @@ 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 +975,7 @@ 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 +993,7 @@ 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 +1009,7 @@ RSpec.describe 'Tags API', type: :request do
             category: 'meta',
             aliases: '',
             parent_tags: '',
+            deprecated: '0',
           }
         }.to change(TagVersion, :count).by(2)
 
@@ -860,6 +1045,7 @@ 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 +1061,7 @@ RSpec.describe 'Tags API', type: :request do
             category: 'nico',
             aliases: '',
             parent_tags: '',
+            deprecated: '0',
           }
         }.not_to change(TagVersion, :count)
 
@@ -896,6 +1083,7 @@ RSpec.describe 'Tags API', type: :request do
             category: 'nico',
             aliases: '',
             parent_tags: '',
+            deprecated: '0',
           }
         }.not_to change(NicoTagVersion, :count)
 
@@ -916,6 +1104,7 @@ RSpec.describe 'Tags API', type: :request do
             category: old_category,
             aliases: '',
             parent_tags: '',
+            deprecated: '0',
           }
         }.not_to change(TagVersion, :count)
 
@@ -946,6 +1135,7 @@ RSpec.describe 'Tags API', type: :request do
             category: 'meme',
             aliases: 'unko',
             parent_tags: '',
+            deprecated: '0',
           }
         }
             .to change(TagVersion, :count).by(2)
@@ -981,6 +1171,7 @@ 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)
@@ -1015,6 +1206,7 @@ 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 +1228,7 @@ RSpec.describe 'Tags API', type: :request do
             category: 'general',
             aliases: 'unko',
             parent_tags: '',
+            deprecated: '0',
           }
         }
             .to change(TagVersion, :count).by(2)

backend/spec/requests/theatre_comments_spec.rb

@@ -80,6 +80,26 @@ RSpec.describe 'TheatreComments', type: :request do
       expect(response).to have_http_status(:ok)
       expect(response.parsed_body.map { |row| row['no'] }).to eq([3, 2, 1])
     end
+
+    it '削除済みコメントは deleted として返し、本文を隠す' do
+      comment_2.discard!
+
+      get "/theatres/#{theatre.id}/comments", params: { no_gt: 1 }
+
+      expect(response).to have_http_status(:ok)
+
+      deleted_comment = response.parsed_body.find { _1['no'] == 2 }
+      expect(deleted_comment).to include(
+        'deleted' => true,
+        'content' => nil
+      )
+
+      visible_comment = response.parsed_body.find { _1['no'] == 3 }
+      expect(visible_comment).to include(
+        'deleted' => false,
+        'content' => 'third comment'
+      )
+    end
   end
 
   describe 'POST /theatres/:theatre_id/comments' do
@@ -147,4 +167,44 @@ RSpec.describe 'TheatreComments', type: :request do
       })
     end
   end
+
+  describe 'DELETE /theatres/:theatre_id/comments/:id' do
+    let(:theatre) { create(:theatre) }
+    let(:alice) { create(:user, name: 'Alice') }
+    let(:bob) { create(:user, name: 'Bob') }
+    let!(:comment) do
+      create(
+        :theatre_comment,
+        theatre: theatre,
+        no: 1,
+        user: alice,
+        content: 'delete target'
+      )
+    end
+
+    it 'returns 401 when not logged in' do
+      delete "/theatres/#{theatre.id}/comments/#{comment.no}"
+
+      expect(response).to have_http_status(:unauthorized)
+      expect(comment.reload.discarded?).to eq(false)
+    end
+
+    it 'allows the comment owner to delete it' do
+      sign_in_as(alice)
+
+      delete "/theatres/#{theatre.id}/comments/#{comment.no}"
+
+      expect(response).to have_http_status(:no_content)
+      expect(comment.reload.discarded?).to eq(true)
+    end
+
+    it 'returns 403 when another user tries to delete it' do
+      sign_in_as(bob)
+
+      delete "/theatres/#{theatre.id}/comments/#{comment.no}"
+
+      expect(response).to have_http_status(:forbidden)
+      expect(comment.reload.discarded?).to eq(false)
+    end
+  end
 end

backend/spec/requests/theatre_programmes_spec.rb

@@ -0,0 +1,38 @@
+require 'rails_helper'
+
+RSpec.describe 'TheatreProgrammes', type: :request do
+  describe 'GET /theatres/:theatre_id/programmes' do
+    let(:theatre) { create(:theatre) }
+    let(:other_theatre) { create(:theatre) }
+    let(:post_1) { Post.create!(title: 'first', url: 'https://www.nicovideo.jp/watch/sm1') }
+    let(:post_2) { Post.create!(title: 'second', url: 'https://www.nicovideo.jp/watch/sm2') }
+    let(:other_post) { Post.create!(title: 'other', url: 'https://www.nicovideo.jp/watch/sm3') }
+
+    before do
+      TheatreProgramme.create!(theatre:, position: 1, post: post_1, created_at: 2.minutes.ago)
+      TheatreProgramme.create!(theatre:, position: 2, post: post_2, created_at: 1.minute.ago)
+      TheatreProgramme.create!(
+        theatre: other_theatre,
+        position: 1,
+        post: other_post,
+        created_at: 1.minute.ago
+      )
+    end
+
+    it 'returns programmes for the theatre in descending position with post json' do
+      get "/theatres/#{theatre.id}/programmes"
+
+      expect(response).to have_http_status(:ok)
+      expect(json.map { _1['position'] }).to eq([2, 1])
+      expect(json.map { _1.dig('post', 'title') }).to eq(['second', 'first'])
+      expect(json.first['post']).to include('id' => post_2.id, 'url' => post_2.url)
+    end
+
+    it 'filters programmes by position_gt' do
+      get "/theatres/#{theatre.id}/programmes", params: { position_gt: 1 }
+
+      expect(response).to have_http_status(:ok)
+      expect(json.map { _1['position'] }).to eq([2])
+    end
+  end
+end

backend/spec/requests/theatres_spec.rb

@@ -14,10 +14,24 @@ RSpec.describe 'Theatres API', type: :request do
   let(:member) { create(:user, :member, name: 'member user') }
   let(:other_user) { create(:user, :member, name: 'other user') }
 
+  let!(:niconico_post) do
+    Post.create!(
+      title: 'niconico post',
+      url: 'https://www.nicovideo.jp/watch/sm123'
+    )
+  end
+
+  let!(:second_niconico_post) do
+    Post.create!(
+      title: 'second niconico post',
+      url: 'https://www.nicovideo.jp/watch/sm456'
+    )
+  end
+
   let!(:youtube_post) do
     Post.create!(
       title: 'youtube post',
-      url: 'https://www.youtube.com/watch?v=spec123'
+      url: 'https://www.youtube.com/watch?v=yt123'
     )
   end
 
@@ -120,7 +134,8 @@ RSpec.describe 'Theatres API', type: :request do
         expect(json).to include(
           'host_flg' => true,
           'post_id' => nil,
-          'post_started_at' => nil
+          'post_started_at' => nil,
+          'post_elapsed_ms' => nil
         )
 
         expect(json.fetch('watching_users')).to contain_exactly(
@@ -177,7 +192,8 @@ RSpec.describe 'Theatres API', type: :request do
         expect(json).to include(
           'host_flg' => false,
           'post_id' => nil,
-          'post_started_at' => nil
+          'post_started_at' => nil,
+          'post_elapsed_ms' => nil
         )
 
         expect(json.fetch('watching_users')).to contain_exactly(
@@ -204,7 +220,7 @@ RSpec.describe 'Theatres API', type: :request do
         )
         theatre.update!(
           host_user: other_user,
-          current_post: youtube_post,
+          current_post: niconico_post,
           current_post_started_at: started_at
         )
         sign_in_as(member)
@@ -220,9 +236,11 @@ RSpec.describe 'Theatres API', type: :request do
         expect(theatre.host_user_id).to eq(member.id)
 
         expect(json['host_flg']).to eq(true)
-        expect(json['post_id']).to eq(youtube_post.id)
+        expect(json['post_id']).to eq(niconico_post.id)
         expect(Time.zone.parse(json['post_started_at']))
           .to be_within(1.second).of(started_at)
+        expect(json['post_elapsed_ms'])
+          .to be_within(1_000).of(120_000)
       end
     end
   end
@@ -273,16 +291,36 @@ RSpec.describe 'Theatres API', type: :request do
       it 'sets current_post to an eligible post and updates current_post_started_at' do
         expect { do_request }
           .to change { theatre.reload.current_post_id }
-          .from(nil).to(youtube_post.id)
 
         expect(response).to have_http_status(:no_content)
+        expect([niconico_post.id, second_niconico_post.id, youtube_post.id])
+          .to include(theatre.reload.current_post_id)
         expect(theatre.reload.current_post_started_at)
           .to be_within(1.second).of(Time.current)
+        expect(theatre.programmes.count).to eq(1)
+      end
+    end
+
+    context 'when only a YouTube post is eligible' do
+      before do
+        niconico_post.destroy!
+        second_niconico_post.destroy!
+        theatre.update!(host_user: member)
+        sign_in_as(member)
+      end
+
+      it 'sets current_post to the YouTube post' do
+        do_request
+
+        expect(response).to have_http_status(:no_content)
+        expect(theatre.reload.current_post_id).to eq(youtube_post.id)
       end
     end
 
     context 'when current user is host and no eligible post exists' do
       before do
+        niconico_post.destroy!
+        second_niconico_post.destroy!
         youtube_post.destroy!
         theatre.update!(
           host_user: member,
@@ -299,9 +337,189 @@ RSpec.describe 'Theatres API', type: :request do
 
         theatre.reload
         expect(theatre.current_post_id).to be_nil
-        expect(theatre.current_post_started_at)
-          .to be_within(1.second).of(Time.current)
+        expect(theatre.current_post_started_at).to be_nil
       end
     end
   end
+
+  describe 'PUT /theatres/:id/skip_vote' do
+    subject(:do_request) do
+      put "/theatres/#{theatre.id}/skip_vote", params: { post_id: requested_post_id }
+    end
+
+    let(:third_user) { create(:user, :member, name: 'third user') }
+    let(:requested_post_id) { niconico_post.id }
+
+    before do
+      theatre.update!(current_post: niconico_post, current_post_started_at: 10.seconds.ago)
+      [member, other_user, third_user].each do |user|
+        TheatreWatchingUser.create!(
+          theatre:,
+          user:,
+          expires_at: 10.seconds.from_now
+        )
+      end
+    end
+
+    it 'returns 401 when not logged in' do
+      sign_out
+
+      expect { do_request }.not_to change(TheatreSkipVote, :count)
+
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it 'returns 422 when post_id is invalid' do
+      sign_in_as(member)
+
+      expect {
+        put "/theatres/#{theatre.id}/skip_vote", params: { post_id: 'invalid' }
+      }.not_to change(TheatreSkipVote, :count)
+
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+
+    it 'records a vote and returns the current vote status before majority' do
+      sign_in_as(member)
+
+      expect { do_request }.to change(TheatreSkipVote, :count).by(1)
+
+      expect(response).to have_http_status(:ok)
+      expect(json['skipped']).to eq(false)
+      expect(json['post_id']).to eq(niconico_post.id)
+      expect(json['skip_vote']).to include(
+        'votes_count' => 1,
+        'required_count' => 2,
+        'watching_users_count' => 3,
+        'voted' => true
+      )
+    end
+
+    it 'finalizes skip when votes reach majority and stores voters and tag snapshots' do
+      tag = create(:tag, name: 'skip-target')
+      PostTag.create!(post: niconico_post, tag:)
+
+      TheatreSkipVote.create!(theatre:, post: niconico_post, user: member)
+      sign_in_as(other_user)
+
+      expect { do_request }
+        .to change(TheatreSkipEvent, :count).by(1)
+        .and change(TheatreSkipEventVoter, :count).by(2)
+        .and change(TheatreSkipEventTag, :count).by(1)
+
+      expect(response).to have_http_status(:ok)
+      expect(json['skipped']).to eq(true)
+      expect([second_niconico_post.id, youtube_post.id]).to include(json['post_id'])
+
+      event = TheatreSkipEvent.last
+      expect(event.post).to eq(niconico_post)
+      expect(event.users).to contain_exactly(member, other_user)
+      expect(event.tags).to contain_exactly(tag)
+      expect(TheatreSkipVote.where(theatre:, post: niconico_post)).to be_empty
+    end
+
+    it 'does not record a vote when requested post is no longer current' do
+      theatre.update!(current_post: second_niconico_post)
+      sign_in_as(member)
+
+      expect { do_request }.not_to change(TheatreSkipVote, :count)
+
+      expect(response).to have_http_status(:conflict)
+      expect(json['post_id']).to eq(second_niconico_post.id)
+      expect(json['skip_vote']).to include(
+        'votes_count' => 0,
+        'voted' => false
+      )
+    end
+  end
+
+  describe 'DELETE /theatres/:id/skip_vote' do
+    let(:requested_post_id) { niconico_post.id }
+
+    before do
+      theatre.update!(current_post: niconico_post, current_post_started_at: 10.seconds.ago)
+      TheatreWatchingUser.create!(theatre:, user: member, expires_at: 10.seconds.from_now)
+      TheatreSkipVote.create!(theatre:, post: niconico_post, user: member)
+      sign_in_as(member)
+    end
+
+    it 'removes the current user vote' do
+      expect {
+        delete "/theatres/#{theatre.id}/skip_vote", params: { post_id: requested_post_id }
+      }.to change(TheatreSkipVote, :count).by(-1)
+
+      expect(response).to have_http_status(:ok)
+      expect(json['skip_vote']).to include(
+        'votes_count' => 0,
+        'required_count' => 1,
+        'watching_users_count' => 1,
+        'voted' => false
+      )
+    end
+
+    it 'does not remove a vote when requested post is no longer current' do
+      theatre.update!(current_post: second_niconico_post)
+
+      expect {
+        delete "/theatres/#{theatre.id}/skip_vote", params: { post_id: requested_post_id }
+      }.not_to change(TheatreSkipVote, :count)
+
+      expect(response).to have_http_status(:conflict)
+      expect(json['post_id']).to eq(second_niconico_post.id)
+    end
+  end
+
+  describe 'GET /theatres/:id/skip_events' do
+    before do
+      sign_in_as(member)
+    end
+
+    it 'does not expose skip voters' do
+      event = TheatreSkipEvent.create!(
+        theatre:,
+        post: niconico_post,
+        skipped_by_user: member,
+        created_at: Time.current
+      )
+      TheatreSkipEventVoter.create!(theatre_skip_event: event, user: member)
+
+      get "/theatres/#{theatre.id}/skip_events"
+
+      expect(response).to have_http_status(:ok)
+      expect(json.first).to include(
+        'id' => event.id,
+        'theatre_id' => theatre.id
+      )
+      expect(json.first).not_to have_key('voters')
+      expect(json.first).not_to have_key('skipped_by_user')
+    end
+  end
+
+  describe 'GET /theatres/:id/post_selection_weights' do
+    before do
+      theatre.update!(current_post: niconico_post)
+      TheatreWatchingUser.create!(theatre:, user: member, expires_at: 10.seconds.from_now)
+      sign_in_as(member)
+    end
+
+    it 'returns tag penalties and candidate weights for the current watchers' do
+      tag = create(:tag, name: 'heavy-tag')
+      PostTag.create!(post: second_niconico_post, tag:)
+      event = TheatreSkipEvent.create!(
+        theatre:,
+        post: niconico_post,
+        skipped_by_user: member,
+        created_at: Time.current
+      )
+      TheatreSkipEventVoter.create!(theatre_skip_event: event, user: member)
+      TheatreSkipEventTag.create!(theatre_skip_event: event, tag:)
+
+      get "/theatres/#{theatre.id}/post_selection_weights"
+
+      expect(response).to have_http_status(:ok)
+      expect(json['tag_penalties'].first['penalty']).to eq(1)
+      expect(json['lightest_posts'].first['post']['id']).to eq(second_niconico_post.id)
+      expect(json['lightest_posts'].first['penalty']).to eq(1)
+    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
       )

backend/spec/services/gekanator/question_suggestion_ai_converter_spec.rb

@@ -0,0 +1,112 @@
+require 'rails_helper'
+
+RSpec.describe Gekanator::QuestionSuggestionAiConverter do
+  let(:user) { create(:user, :member) }
+  let(:guessed_post) { Post.create!(title: 'guess', url: 'https://example.com/guess') }
+  let(:correct_post) { Post.create!(title: 'correct', url: 'https://example.com/correct') }
+  let(:game) do
+    GekanatorGame.create!(
+      user: user,
+      guessed_post: guessed_post,
+      correct_post: correct_post,
+      won: false,
+      question_count: 1,
+      answers: [{ 'question_id' => 'tag:1', 'answer' => 'yes' }]
+    )
+  end
+
+  def create_suggestion!(question_text:, answer: 'yes')
+    GekanatorQuestionSuggestion.create!(
+      gekanator_game: game,
+      user: user,
+      question_text: question_text,
+      answer: answer
+    )
+  end
+
+  it 'converts title-contains suggestions to pending ai-generated questions' do
+    suggestion = create_suggestion!(question_text: '題名に「結束バンド」が含まれる?')
+
+    expect {
+      described_class.call(suggestion: suggestion, user: user)
+    }.to change { GekanatorQuestion.count }.by(1)
+      .and change { GekanatorAiRun.count }.by(1)
+
+    question = GekanatorQuestion.last
+    expect(question).to have_attributes(
+      text: '題名に「結束バンド」が含まれる?',
+      kind: 'title',
+      source: 'ai_generated',
+      status: 'pending',
+      priority_weight: 0.95,
+      gekanator_question_suggestion_id: suggestion.id,
+      created_by_id: user.id
+    )
+    expect(question.condition).to include(
+      'type' => 'title-contains',
+      'text' => '結束バンド'
+    )
+    expect(GekanatorAiRun.last).to have_attributes(
+      gekanator_question_suggestion_id: suggestion.id,
+      model: 'heuristic_converter_v1',
+      status: 'succeeded'
+    )
+  end
+
+  it 'converts concrete non-unknown suggestions to post-similarity questions' do
+    suggestion = create_suggestion!(
+      question_text: '喜多ちゃんが泣いてる?',
+      answer: 'partial'
+    )
+
+    question = described_class.call(suggestion: suggestion, user: user)
+
+    expect(question).to have_attributes(
+      text: '喜多ちゃんが泣いてる?',
+      kind: 'post_similarity',
+      source: 'ai_generated',
+      status: 'pending',
+      priority_weight: 1.0
+    )
+    expect(question.condition).to include(
+      'type' => 'post-similarity',
+      'postId' => correct_post.id,
+      'answer' => 'partial',
+      'threshold' => 0.65
+    )
+  end
+
+  it 'records a failed run when the suggestion cannot be converted' do
+    suggestion = create_suggestion!(
+      question_text: 'よく分からない質問?',
+      answer: 'unknown'
+    )
+
+    expect {
+      expect(described_class.call(suggestion: suggestion, user: user)).to be_nil
+    }.not_to change { GekanatorQuestion.count }
+
+    expect(GekanatorAiRun.last).to have_attributes(
+      gekanator_question_suggestion_id: suggestion.id,
+      status: 'failed'
+    )
+  end
+
+  it 'returns an existing generated question without creating a duplicate run' do
+    suggestion = create_suggestion!(question_text: 'タイトルは 10 文字以上?')
+    existing = GekanatorQuestion.create!(
+      text: 'タイトルは 10 文字以上?',
+      kind: 'title',
+      source: 'ai_generated',
+      status: 'pending',
+      priority_weight: 0.95,
+      condition: { type: 'title-length-at-least', length: 10 },
+      gekanator_question_suggestion: suggestion,
+      created_by: user
+    )
+
+    expect {
+      expect(described_class.call(suggestion: suggestion, user: user)).to eq(existing)
+    }.not_to change { GekanatorAiRun.count }
+  end
+end

backend/spec/tasks/post_similarity_calc_spec.rb

@@ -4,11 +4,12 @@ require 'rails_helper'
 RSpec.describe 'post_similarity:calc' do
   include RakeTaskHelper
 
-  it 'calls Similarity::Calc with Post and :tags' do
+  it 'calculates similarities from active tags only' do
     # 必要最低限のデータ
     t1 = Tag.create!(name: "t1")
     t2 = Tag.create!(name: "t2")
     t3 = Tag.create!(name: "t3")
+    deprecated_tag = Tag.create!(name: 'deprecated', deprecated_at: Time.current)
 
     p1 = Post.create!(url: "https://example.com/1")
     p2 = Post.create!(url: "https://example.com/2")
@@ -22,6 +23,8 @@ RSpec.describe 'post_similarity:calc' do
     PostTag.create!(post: p2, tag: t3)
 
     PostTag.create!(post: p3, tag: t3)
+    PostTag.create!(post: p1, tag: deprecated_tag)
+    PostTag.create!(post: p2, tag: deprecated_tag)
 
     expect { run_rake_task("post_similarity:calc") }
       .to change { PostSimilarity.count }.from(0)
@@ -29,6 +32,6 @@ RSpec.describe 'post_similarity:calc' do
     ps = PostSimilarity.find_by!(post_id: p1.id, target_post_id: p2.id)
     ps_rev = PostSimilarity.find_by!(post_id: p2.id, target_post_id: p1.id)
     expect(ps_rev.cos).to eq(ps.cos)
+    expect(ps.cos).to be_within(0.0001).of(0.5)
   end
 end
-

backend/spec/tasks/tag_similarity_calc_spec.rb

@@ -4,11 +4,12 @@ require 'rails_helper'
 RSpec.describe 'tag_similarity:calc' do
   include RakeTaskHelper
 
-  it 'calls Similarity::Calc with Tag and :posts' do
+  it 'calculates similarities for active tags only' do
     # 必要最低限のデータ
     t1 = Tag.create!(name: "t1")
     t2 = Tag.create!(name: "t2")
     t3 = Tag.create!(name: "t3")
+    deprecated_tag = Tag.create!(name: 'deprecated', deprecated_at: Time.current)
 
     p1 = Post.create!(url: "https://example.com/1")
     p2 = Post.create!(url: "https://example.com/2")
@@ -22,6 +23,7 @@ RSpec.describe 'tag_similarity:calc' do
     PostTag.create!(post: p2, tag: t3)
 
     PostTag.create!(post: p3, tag: t3)
+    PostTag.create!(post: p1, tag: deprecated_tag)
 
     expect { run_rake_task("tag_similarity:calc") }
       .to change { TagSimilarity.count }.from(0)
@@ -29,6 +31,7 @@ RSpec.describe 'tag_similarity:calc' do
     ps = TagSimilarity.find_by!(tag_id: t1.id, target_tag_id: t2.id)
     ps_rev = TagSimilarity.find_by!(tag_id: t2.id, target_tag_id: t1.id)
     expect(ps_rev.cos).to eq(ps.cos)
+    expect(TagSimilarity.where(tag_id: deprecated_tag.id)).to be_empty
+    expect(TagSimilarity.where(target_tag_id: deprecated_tag.id)).to be_empty
   end
 end
-

frontend/AGENTS.md

@@ -4,7 +4,8 @@
 
 These rules apply to work under `frontend/`.
 
-This is a Vite + React + TypeScript app using TanStack Query, Tailwind CSS, Framer Motion, Radix UI-style components, MDX, and Zustand.
+This is a Vite + React + TypeScript app using TanStack Query, Tailwind CSS,
+Framer Motion, Radix UI-style components, MDX, and Zustand.
 
 ## Commands
 
@@ -17,9 +18,11 @@ npm run lint
 npm run preview
 ```
 
-`npm run build` runs `tsc -b && vite build`, and `postbuild` runs `node scripts/generate-sitemap.js`.
+`npm run build` runs `tsc -b && vite build`, and `postbuild` runs
+`node scripts/generate-sitemap.js`.
 
-There is currently no `test` script in `package.json`. Do not run or report `npm test` unless a test script is added.
+There is currently no `test` script in `package.json`. Do not run or report
+`npm test` unless a test script is added.
 
 After frontend changes, run:
 
@@ -30,20 +33,43 @@ npm run lint
 
 If either command cannot be run or fails, report the exact command and failure.
 
+Do not create, modify, or run tests unless the user explicitly asks for test
+work. When the user asks for tests, keep working and rerun them until they
+pass or the remaining failure is clearly blocked.
+
 ## TypeScript
 
-- TypeScript is strict. `tsconfig.app.json` enables `strict`, `noUnusedLocals`, `noUnusedParameters`, `erasableSyntaxOnly`, `noFallthroughCasesInSwitch`, and `noUncheckedSideEffectImports`.
+- TypeScript is strict. `tsconfig.app.json` enables `strict`,
+  `noUnusedLocals`, `noUnusedParameters`, `erasableSyntaxOnly`,
+  `noFallthroughCasesInSwitch`, and `noUncheckedSideEffectImports`.
 - Keep types explicit at module boundaries, API helpers, and exported utilities.
 - Use `import type` for type-only imports.
 - Prefer existing shared types from `src/types.ts` before adding local duplicate types.
-- Preserve the repository's existing spacing style in TypeScript, including GNU-style spacing before call parentheses where it is already used.
+- Preserve the repository's existing spacing style in TypeScript, including
+  GNU-style spacing before call parentheses where it is already used.
 - Prefer single quotes for strings unless interpolation or escaping makes double quotes better.
+- Never write a TypeScript or TSX line longer than 99 characters.
+- Aim to keep TypeScript and TSX lines within 79 characters where practical.
+- Use 4-space logical indentation in TypeScript and TSX.
+- For arrays, never put whitespace or a line break immediately before `]`.
+- Keep the first element on the same line as `[` by default.
+- If an array would exceed the line limit, break after `[` and indent
+  elements by 4 spaces.
+- In TypeScript and TSX only, replace every leading run of 8 spaces with a tab
+  to reduce bytes.
+- Treat one leading tab as exactly equivalent to 8 leading spaces.
+- Use tabs only for leading indentation. Never replace spaces that occur after
+  a non-space character on the same line.
 
 ## React
 
 - Use function components.
-- Existing page components commonly export an anonymous function satisfying `FC`; match nearby file style when editing.
+- Existing page components commonly export an anonymous function satisfying
+  `FC`; match nearby file style when editing.
 - React hooks must be called unconditionally and at the top level of components or custom hooks.
+- Gate editing and other privileged controls with shared permission helpers
+  such as `canEditContent`, instead of showing controls and relying only on a
+  later API failure.
 - Keep page-level components under `src/pages`.
 - Keep shared and feature components under `src/components`.
 - Use `react-router-dom` route params and navigation patterns already present in `src/App.tsx`.
@@ -52,17 +78,23 @@ If either command cannot be run or fails, report the exact command and failure.
 ## TanStack Query
 
 - Use `@tanstack/react-query` for server state.
-- Query keys should come from `src/lib/queryKeys.ts`; add key builders there instead of using ad hoc arrays in components.
-- Fetch functions should live in domain helpers under `src/lib`, such as `posts.ts`, `tags.ts`, or `wiki.ts`.
-- Use `useQueryClient().invalidateQueries` with the shared root keys when mutations affect cached lists or detail views.
-- The app-wide `QueryClient` is configured in `src/main.tsx`; do not create additional clients in feature code.
+- Query keys should come from `src/lib/queryKeys.ts`; add key builders there
+  instead of using ad hoc arrays in components.
+- Fetch functions should live in domain helpers under `src/lib`, such as
+  `posts.ts`, `tags.ts`, or `wiki.ts`.
+- Use `useQueryClient().invalidateQueries` with the shared root keys when
+  mutations affect cached lists or detail views.
+- The app-wide `QueryClient` is configured in `src/main.tsx`; do not create
+  additional clients in feature code.
 
 ## API calls
 
 - Use `src/lib/api.ts` for HTTP calls.
-- The API wrapper attaches `X-Transfer-Code` from `localStorage` and converts non-blob responses to camelCase.
+- The API wrapper attaches `X-Transfer-Code` from `localStorage` and converts
+  non-blob responses to camelCase.
 - Send Rails snake_case params and request body keys where the backend expects them.
-- Do not bypass the API wrapper unless there is a specific reason, such as a third-party request outside the Rails API.
+- Do not bypass the API wrapper unless there is a specific reason, such as a
+  third-party request outside the Rails API.
 - For blob responses, pass `responseType: 'blob'` so the wrapper does not camelCase the body.
 
 ## Imports and aliases
@@ -76,17 +108,41 @@ If either command cannot be run or fails, report the exact command and failure.
 
 - Tailwind scans `src/**/*.{html,js,ts,jsx,tsx,mdx}`.
 - Use `cn` from `src/lib/utils.ts` for conditional class names and class merging.
-- Reuse components from `src/components/common`, `src/components/layout`, and `src/components/ui` before adding new primitives.
+- Reuse components from `src/components/common`, `src/components/layout`, and
+  `src/components/ui` before adding new primitives.
 - Keep Tailwind classes consistent with nearby components.
-- When adding dynamic tag color classes, update `tailwind.config.js` safelist if the class cannot be statically detected.
+- Prefer restrained, content-first UI chrome: avoid adding card backgrounds,
+  heavy borders, or nested panel decoration unless the surrounding screen
+  already uses them.
+- Keep operational screens dense and direct; trim explanatory copy and use
+  short Japanese labels that fit the control.
+- Preserve existing Japanese tone and orthography in nearby UI text, including
+  old-kana wording where the file already uses it.
+- When adding dynamic tag color classes, update `tailwind.config.js` safelist
+  if the class cannot be statically detected.
 - Do not introduce new UI libraries or production dependencies without approval.
 
+## TSX formatting
+
+- Preserve compact TSX expression shapes such as inline ternary branches and
+  closing `</div>)` forms when nearby code uses them.
+- For long Tailwind `className` strings, wrap across lines only when needed.
+- Keep continuation indentation aligned with the 4-space logical indentation
+  rule, using tabs only as leading 8-space compression.
+- Do not add braces around `if`, `else`, or `for` bodies when the body is a
+  single physical line.
+- Always add braces around `if`, `else`, or `for` bodies when the body spans
+  two or more physical lines, even if it is one statement.
+- Avoid reformatting unrelated JSX.
+
 ## Lint and build constraints
 
-- ESLint uses `@eslint/js`, `typescript-eslint`, `eslint-plugin-react-hooks`, and `eslint-plugin-react-refresh`.
+- ESLint uses `@eslint/js`, `typescript-eslint`, `eslint-plugin-react-hooks`,
+  and `eslint-plugin-react-refresh`.
 - The hooks rules are enforced; fix hook ordering instead of disabling the rule.
 - `react-refresh/only-export-components` is enabled as a warning with `allowConstantExport`.
-- Build failures from unused locals or unused parameters are TypeScript errors, not lint-only issues.
+- Build failures from unused locals or unused parameters are TypeScript
+  errors, not lint-only issues.
 
 ## Files to avoid in routine work
 

frontend/src/App.tsx

@@ -18,6 +18,7 @@ import MaterialListPage from '@/pages/materials/MaterialListPage'
 import MaterialNewPage from '@/pages/materials/MaterialNewPage'
 // import MaterialSearchPage from '@/pages/materials/MaterialSearchPage'
 import MorePage from '@/pages/MorePage'
+import GekanatorPage from '@/pages/GekanatorPage'
 import NicoTagListPage from '@/pages/tags/NicoTagListPage'
 import NotFound from '@/pages/NotFound'
 import TOSPage from '@/pages/TOSPage.mdx'
@@ -64,11 +65,11 @@ const RouteTransitionWrapper = ({ user, setUser }: {
 	  <Route path="/tags/nico" element={<NicoTagListPage user={user}/>}/>
 	  <Route path="/nico/tags" element={<NicoTagListPage user={user}/>}/>
 	  <Route path="/tags/changes" element={<TagHistoryPage/>}/>
-	  <Route path="/theatres/:id" element={<TheatreDetailPage/>}/>
+	  <Route path="/theatres/:id" element={<TheatreDetailPage user={user}/>}/>
 	  <Route path="/materials" element={<MaterialBasePage/>}>
 	    <Route index element={<MaterialListPage/>}/>
 	    <Route path="new" element={<MaterialNewPage/>}/>
-	    <Route path=":id" element ={<MaterialDetailPage/>}/>
+	    <Route path=":id" element ={<MaterialDetailPage user={user}/>}/>
 	  </Route>
 	  {/* <Route path="/materials/search" element={<MaterialSearchPage/>}/> */}
 	  <Route path="/wiki" element={<WikiSearchPage/>}/>
@@ -80,6 +81,7 @@ const RouteTransitionWrapper = ({ user, setUser }: {
 	  <Route path="/users/settings" element={<SettingPage user={user} setUser={setUser}/>}/>
 	  <Route path="/settings" element={<Navigate to="/users/settings" replace/>}/>
 	  <Route path="/tos" element={<TOSPage/>}/>
+	  <Route path="/gekanator" element={<GekanatorPage user={user}/>}/>
 	  <Route path="/more" element={<MorePage/>}/>
 	  <Route path="*" element={<NotFound/>}/>
 	</Routes>

frontend/src/components/NicoViewer.test.tsx

@@ -0,0 +1,83 @@
+import { act, fireEvent, render } from '@testing-library/react'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { createRef } from 'react'
+
+import NicoViewer from '@/components/NicoViewer'
+
+import type { NiconicoViewerHandle } from '@/types'
+
+
+describe ('NicoViewer', () => {
+  afterEach (() => {
+    vi.useRealTimers ()
+  })
+
+  it ('does not time out after metadata reports a playable duration', () => {
+    vi.useFakeTimers ()
+
+    const onError = vi.fn ()
+    const onMetadataChange = vi.fn ()
+    const { container } = render (
+        <NicoViewer
+            id="sm12345"
+            width={640}
+            height={360}
+            onMetadataChange={onMetadataChange}
+            onError={onError}/>,
+    )
+    const iframe = container.querySelector ('iframe')
+    expect (iframe).not.toBeNull ()
+
+    fireEvent.load (iframe!)
+    act (() => {
+      window.dispatchEvent (new MessageEvent ('message', {
+        origin: 'https://embed.nicovideo.jp',
+        source: iframe!.contentWindow,
+        data:   {
+          eventName: 'playerMetadataChange',
+          data:      {
+            currentTime:           7,
+            duration:              120,
+            isVideoMetaDataLoaded: true,
+            maximumBuffered:       30,
+            muted:                 false,
+            showComment:           true,
+            volume:                1,
+          },
+        },
+      }))
+    })
+
+    act (() => {
+      vi.advanceTimersByTime (8_000)
+    })
+
+    expect (onMetadataChange).toHaveBeenCalled ()
+    expect (onError).not.toHaveBeenCalled ()
+  })
+
+  it ('seeks with milliseconds', () => {
+    const ref = createRef<NiconicoViewerHandle> ()
+    const { container } = render (
+        <NicoViewer
+            ref={ref}
+            id="sm12345"
+            width={640}
+            height={360}/>,
+    )
+    const iframe = container.querySelector ('iframe')!
+    const postMessage = vi.spyOn (iframe.contentWindow!, 'postMessage')
+
+    act (() => {
+      ref.current!.seek (7_000)
+    })
+
+    expect (postMessage).toHaveBeenCalledWith (
+        expect.objectContaining ({
+          eventName: 'seek',
+          data:      { time: 7_000 },
+        }),
+        'https://embed.nicovideo.jp',
+    )
+  })
+})

frontend/src/components/NicoViewer.tsx

@@ -1,11 +1,11 @@
 import { forwardRef,
-         useCallback,
-         useEffect,
-         useImperativeHandle,
-         useLayoutEffect,
-         useMemo,
-         useRef,
-         useState } from 'react'
+	 useCallback,
+	 useEffect,
+	 useImperativeHandle,
+	 useLayoutEffect,
+	 useMemo,
+	 useRef,
+	 useState } from 'react'
 
 import type { CSSProperties, ForwardedRef } from 'react'
 
@@ -14,10 +14,20 @@ import type { NiconicoMetadata, NiconicoVideoInfo, NiconicoViewerHandle } from '
 type NiconicoPlayerMessage =
     | { eventName: 'enterProgrammaticFullScreen' }
     | { eventName: 'exitProgrammaticFullScreen' }
-    | { eventName: 'loadComplete'; playerId?: string; data: { videoInfo: NiconicoVideoInfo } }
-    | { eventName: 'playerMetadataChange'; playerId?: string; data: NiconicoMetadata }
-    | { eventName: 'playerStatusChange' | 'statusChange'; playerId?: string; data?: unknown }
-    | { eventName: 'error'; playerId?: string; data?: unknown; code?: string; message?: string }
+    | { eventName: 'loadComplete'
+	playerId?:  string
+	data:       { videoInfo: NiconicoVideoInfo } }
+    | { eventName: 'playerMetadataChange'
+	playerId?:  string
+	data:       NiconicoMetadata }
+    | { eventName: 'playerStatusChange' | 'statusChange'
+	playerId?:  string
+	data?:      unknown }
+    | { eventName: 'error'
+	playerId?:  string
+	data?:      unknown
+	code?:      string
+	message?:   string }
 
 type NiconicoCommand =
     | { eventName: 'play'; sourceConnectorType: 1; playerId: string }
@@ -30,6 +40,7 @@ type NiconicoCommand =
 	data: { commentVisibility: boolean } }
 
 const EMBED_ORIGIN = 'https://embed.nicovideo.jp'
+const LOAD_COMPLETE_TIMEOUT_MS = 8_000
 
 type Props = {
     id:                 string
@@ -37,14 +48,18 @@ type Props = {
     height:             number
     style?:             CSSProperties
     onLoadComplete?:    (info: NiconicoVideoInfo) => void
-    onMetadataChange?:  (meta: NiconicoMetadata) => void }
+    onMetadataChange?:  (meta: NiconicoMetadata) => void
+    onError?:           (data: unknown) => void }
 
 
 export default forwardRef ((props: Props, ref: ForwardedRef<NiconicoViewerHandle>) => {
-  const { id, width, height, style = { }, onLoadComplete, onMetadataChange } = props
+  const { id, width, height, style = { }, onLoadComplete, onMetadataChange, onError } = props
 
   const iframeRef = useRef<HTMLIFrameElement> (null)
-  const playerId = useMemo (() => `nico-${ id }-${ Math.random ().toString (36).slice (2) }`, [id])
+  const loadCompleteTimerRef = useRef<ReturnType<typeof setTimeout> | null> (null)
+  const playerId = useMemo (
+      () => `nico-${ id }-${ Math.random ().toString (36).slice (2) }`,
+      [id])
 
   const [screenWidth, setScreenWidth] = useState<CSSProperties['width']> ()
   const [screenHeight, setScreenHeight] = useState<CSSProperties['height']> ()
@@ -64,21 +79,39 @@ export default forwardRef ((props: Props, ref: ForwardedRef<NiconicoViewerHandle
   const styleFullScreen: CSSProperties =
       fullScreen
       ? { top: 0,
-          left: landscape ? 0 : '100%',
-          position: 'fixed',
-          width: screenWidth,
-          height: screenHeight,
-          zIndex: 2_147_483_647,
-          maxWidth: 'none',
-          transformOrigin: '0% 0%',
-          transform: landscape ? 'none' : 'rotate(90deg)',
-          WebkitTransformOrigin: '0% 0%',
-          WebkitTransform: landscape ? 'none' : 'rotate(90deg)' }
+	  left: landscape ? 0 : '100%',
+	  position: 'fixed',
+	  width: screenWidth,
+	  height: screenHeight,
+	  zIndex: 2_147_483_647,
+	  maxWidth: 'none',
+	  transformOrigin: '0% 0%',
+	  transform: landscape ? 'none' : 'rotate(90deg)',
+	  WebkitTransformOrigin: '0% 0%',
+	  WebkitTransform: landscape ? 'none' : 'rotate(90deg)' }
       : { }
 
   const margedStyle: CSSProperties =
       { border: 'none', maxWidth: '100%', ...style, ...styleFullScreen }
 
+  const clearLoadCompleteTimer = useCallback (() => {
+    if (!(loadCompleteTimerRef.current))
+      return
+
+    clearTimeout (loadCompleteTimerRef.current)
+    loadCompleteTimerRef.current = null
+  }, [])
+
+  const startLoadCompleteTimer = useCallback (() => {
+    clearLoadCompleteTimer ()
+    loadCompleteTimerRef.current = setTimeout (() => {
+      onError?.({
+	  eventName: 'loadCompleteTimeout',
+	  reason:    'niconico video length was not reported by embed',
+      })
+    }, LOAD_COMPLETE_TIMEOUT_MS)
+  }, [clearLoadCompleteTimer, onError])
+
   const postToPlayer = useCallback ((message: NiconicoCommand) => {
     const win = iframeRef.current?.contentWindow
     if (!(win))
@@ -96,7 +129,9 @@ export default forwardRef ((props: Props, ref: ForwardedRef<NiconicoViewerHandle
   }, [playerId, postToPlayer])
 
   const seek = useCallback ((time: number) => {
-    postToPlayer ({ eventName: 'seek', sourceConnectorType: 1, playerId, data: { time } })
+    postToPlayer (
+	{ eventName: 'seek', sourceConnectorType: 1, playerId,
+	  data: { time } })
   }, [playerId, postToPlayer])
 
   const mute = useCallback (() => {
@@ -132,21 +167,21 @@ export default forwardRef ((props: Props, ref: ForwardedRef<NiconicoViewerHandle
   useEffect (() => {
     const onMessage = (event: MessageEvent<NiconicoPlayerMessage>) => {
       if (!(iframeRef.current)
-          || (event.source !== iframeRef.current.contentWindow)
-          || (event.origin !== EMBED_ORIGIN))
-        return
+	  || (event.source !== iframeRef.current.contentWindow)
+	  || (event.origin !== EMBED_ORIGIN))
+	return
 
       const data = event.data
 
       if (!(data)
 	  || typeof data !== 'object'
 	  || !('eventName' in data))
-        return
+	return
 
       if (('playerId' in data)
 	  && data.playerId
 	  && data.playerId !== playerId)
-        return
+	return
 
       if (data.eventName === 'enterProgrammaticFullScreen')
 	{
@@ -162,24 +197,34 @@ export default forwardRef ((props: Props, ref: ForwardedRef<NiconicoViewerHandle
 
       if (data.eventName === 'loadComplete')
 	{
+	  clearLoadCompleteTimer ()
 	  onLoadComplete?.(data.data.videoInfo)
 	  return
 	}
 
       if (data.eventName === 'playerMetadataChange')
 	{
+	  if (Number.isFinite (data.data.duration) && data.data.duration > 0)
+	    clearLoadCompleteTimer ()
+
 	  onMetadataChange?.(data.data)
 	  return
 	}
 
       if (data.eventName === 'error')
-        console.error ('niconico player error:', data)
+	{
+	  clearLoadCompleteTimer ()
+	  console.error ('niconico player error:', data)
+	  onError?.(data)
+	}
     }
 
     addEventListener ('message', onMessage)
 
     return () => removeEventListener ('message', onMessage)
-  }, [onLoadComplete, onMetadataChange, playerId])
+  }, [clearLoadCompleteTimer, onError, onLoadComplete, onMetadataChange, playerId])
+
+  useEffect (() => clearLoadCompleteTimer, [clearLoadCompleteTimer])
 
   useLayoutEffect (() => {
     if (!(fullScreen))
@@ -192,7 +237,7 @@ export default forwardRef ((props: Props, ref: ForwardedRef<NiconicoViewerHandle
 
     const pollingResize = () => {
       if (ended)
-        return
+	return
 
       const isLandscape = innerWidth >= innerHeight
       const windowWidth = `${ isLandscape ? innerWidth : innerHeight }px`
@@ -206,9 +251,9 @@ export default forwardRef ((props: Props, ref: ForwardedRef<NiconicoViewerHandle
 
     const startPollingResize = () => {
       if (requestAnimationFrame)
-        requestAnimationFrame (pollingResize)
+	requestAnimationFrame (pollingResize)
       else
-        pollingResize ()
+	pollingResize ()
     }
 
     startPollingResize ()
@@ -231,9 +276,10 @@ export default forwardRef ((props: Props, ref: ForwardedRef<NiconicoViewerHandle
       <iframe
 	  ref={iframeRef}
 	  src={src}
-	  width={width}
-	  height={height}
-	  style={margedStyle}
-	  allowFullScreen
-	  allow="autoplay"/>)
+		  width={width}
+		  height={height}
+		  style={margedStyle}
+		  onLoad={startLoadCompleteTimer}
+		  allowFullScreen
+		  allow="autoplay"/>)
 })

frontend/src/components/PostEmbed.test.tsx

@@ -8,12 +8,19 @@ const dialogue = vi.hoisted (() => ({
   confirm: vi.fn (),
 }))
 
+const nicoViewer = vi.hoisted (() => ({
+  props: vi.fn (),
+}))
+
 vi.mock ('@/components/dialogues/DialogueProvider', () => ({
   useDialogue: () => dialogue,
 }))
 
 vi.mock ('@/components/NicoViewer', () => ({
-  default: ({ id }: { id: string }) => <div>Nico:{id}</div>,
+  default: (props: { id: string }) => {
+    nicoViewer.props (props)
+    return <div>Nico:{props.id}</div>
+  },
 }))
 
 vi.mock ('react-youtube', () => ({
@@ -31,6 +38,64 @@ describe ('PostEmbed', () => {
     expect (screen.getByText ('Nico:sm12345')).toBeInTheDocument ()
   })
 
+  it ('reports niconico metadata as milliseconds', () => {
+    const onVideoReady = vi.fn ()
+    const onPlaybackChange = vi.fn ()
+    render (
+        <PostEmbed
+            post={buildPost ({ url: 'https://www.nicovideo.jp/watch/sm12345' })}
+            onVideoReady={onVideoReady}
+            onPlaybackChange={onPlaybackChange}/>,
+    )
+
+    nicoViewer.props.mock.calls[0][0].onMetadataChange ({
+      currentTime:            7_000,
+      duration:               120_000,
+      isVideoMetaDataLoaded:  true,
+      maximumBuffered:        30,
+      muted:                  false,
+      showComment:            true,
+      volume:                 1,
+    })
+
+    expect (onVideoReady).toHaveBeenCalledWith (120_000)
+    expect (onPlaybackChange).toHaveBeenCalledWith (7_000)
+  })
+
+  it ('reports niconico video readiness only once', () => {
+    const onVideoReady = vi.fn ()
+    render (
+        <PostEmbed
+            post={buildPost ({ url: 'https://www.nicovideo.jp/watch/sm12345' })}
+            onVideoReady={onVideoReady}/>,
+    )
+
+    nicoViewer.props.mock.calls[0][0].onLoadComplete ({
+      title:           '動画',
+      videoId:         'sm12345',
+      lengthInSeconds: 120,
+      thumbnailUrl:    'https://example.com/thumb.jpg',
+      description:     '',
+      viewCount:       1,
+      commentCount:    2,
+      mylistCount:     3,
+      postedAt:        '2026-01-02T03:04:05.000Z',
+      watchId:         12345,
+    })
+    nicoViewer.props.mock.calls[0][0].onMetadataChange ({
+      currentTime:            7_000,
+      duration:               120_000,
+      isVideoMetaDataLoaded:  true,
+      maximumBuffered:        30,
+      muted:                  false,
+      showComment:            true,
+      volume:                 1,
+    })
+
+    expect (onVideoReady).toHaveBeenCalledTimes (1)
+    expect (onVideoReady).toHaveBeenCalledWith (120_000)
+  })
+
   it ('embeds x/twitter status URLs', () => {
     render (<PostEmbed post={buildPost ({ url: 'https://x.com/someone/status/12345' })}/>)
 

frontend/src/components/PostEmbed.tsx

@@ -1,4 +1,4 @@
-import { useState } from 'react'
+import { useCallback, useEffect, useRef, useState } from 'react'
 import YoutubeEmbed from 'react-youtube'
 
 import NicoViewer from '@/components/NicoViewer'
@@ -8,17 +8,113 @@ import { useDialogue } from '@/components/dialogues/DialogueProvider'
 import type { FC, RefObject } from 'react'
 
 import type { NiconicoMetadata, NiconicoVideoInfo, NiconicoViewerHandle, Post } from '@/types'
+import type { YouTubePlayer } from 'react-youtube'
+
+type YouTubeEvent<T = unknown> = {
+    data:    T
+    target:  YouTubePlayer }
 
 type Props = {
     ref?:               RefObject<NiconicoViewerHandle | null>
     post:               Post
     onLoadComplete?:    (info: NiconicoVideoInfo) => void
-    onMetadataChange?:  (meta: NiconicoMetadata) => void }
+    onMetadataChange?:  (meta: NiconicoMetadata) => void
+    onVideoReady?:      (durationMs: number) => void
+    onPlaybackChange?:  (currentTimeMs: number) => number | void
+    onError?:           (data: unknown) => void }
 
 
-const PostEmbed: FC<Props> = ({ ref, post, onLoadComplete, onMetadataChange }) => {
+const PostEmbed: FC<Props> = ({
+    ref,
+    post,
+    onLoadComplete,
+    onMetadataChange,
+    onVideoReady,
+    onPlaybackChange,
+    onError,
+}) => {
   const dialogue = useDialogue ()
   const [framed, setFramed] = useState (false)
+  const [youtubePlayer, setYoutubePlayer] = useState<YouTubePlayer | null> (null)
+  const niconicoVideoReadyRef = useRef (false)
+
+  const notifyNiconicoVideoReady = useCallback ((durationMs: number) => {
+    if (niconicoVideoReadyRef.current
+	|| !(Number.isFinite (durationMs))
+	|| durationMs <= 0)
+      return
+
+    niconicoVideoReadyRef.current = true
+    onVideoReady?.(durationMs)
+  }, [onVideoReady])
+
+  const reportYoutubePlayback = useCallback (async (player: YouTubePlayer) => {
+    const currentTime = await player.getCurrentTime ()
+    const currentTimeMs = currentTime * 1_000
+    const targetTimeMs = onPlaybackChange?.(currentTimeMs)
+
+    if (typeof targetTimeMs !== 'number')
+      return
+
+    if (Math.abs (currentTimeMs - targetTimeMs) > 5_000)
+      await player.seekTo (targetTimeMs / 1_000, true)
+  }, [onPlaybackChange])
+
+  const handleYoutubeReady = async (event: YouTubeEvent) => {
+    setYoutubePlayer (event.target)
+
+    try
+    {
+      await event.target.playVideo ()
+
+      const duration = await event.target.getDuration ()
+      const durationMs = duration * 1_000
+      onVideoReady?.(durationMs)
+
+      if (!(Number.isFinite (durationMs)) || durationMs <= 0)
+	return
+
+      await reportYoutubePlayback (event.target)
+    }
+    catch (error)
+    {
+      onError?.({ platform: 'youtube', error })
+    }
+  }
+
+  const handleYoutubeStateChange = (event: YouTubeEvent<number>) => {
+    void reportYoutubePlayback (event.target)
+  }
+
+  const handleYoutubeError = (event: YouTubeEvent<number>) => {
+    onError?.({ platform: 'youtube', code: event.data })
+  }
+
+  const handleNiconicoLoadComplete = (info: NiconicoVideoInfo) => {
+    notifyNiconicoVideoReady (info.lengthInSeconds * 1_000)
+    onLoadComplete?.(info)
+  }
+
+  const handleNiconicoMetadataChange = (meta: NiconicoMetadata) => {
+    notifyNiconicoVideoReady (meta.duration)
+    onPlaybackChange?.(meta.currentTime)
+    onMetadataChange?.(meta)
+  }
+
+  useEffect (() => {
+    niconicoVideoReadyRef.current = false
+  }, [post.url])
+
+  useEffect (() => {
+    if (!(youtubePlayer) || !(onPlaybackChange))
+      return
+
+    const timer = setInterval (
+	() => void reportYoutubePlayback (youtubePlayer),
+	1_000)
+
+    return () => clearInterval (timer)
+  }, [onPlaybackChange, reportYoutubePlayback, youtubePlayer])
 
   const url = new URL (post.url)
 
@@ -38,8 +134,9 @@ const PostEmbed: FC<Props> = ({ ref, post, onLoadComplete, onMetadataChange }) =
 	      id={videoId}
 	      width={640}
 	      height={360}
-	      onLoadComplete={onLoadComplete}
-	      onMetadataChange={onMetadataChange}/>)
+	      onLoadComplete={handleNiconicoLoadComplete}
+	      onMetadataChange={handleNiconicoMetadataChange}
+	      onError={onError}/>)
     }
 
   case 'twitter.com':
@@ -69,7 +166,10 @@ const PostEmbed: FC<Props> = ({ ref, post, onLoadComplete, onMetadataChange }) =
 	      mute:         0,
 	      loop:         1,
 	      width:        '640',
-	      height:       '360' } }}/>)
+	      height:       '360' } }}
+	      onReady={handleYoutubeReady}
+	      onStateChange={handleYoutubeStateChange}
+	      onError={handleYoutubeError}/>)
     }
   }
 

frontend/src/components/TagLink.test.tsx

@@ -18,6 +18,21 @@ describe ('TagLink', () => {
     expect (screen.getByText ('4')).toBeInTheDocument ()
   })
 
+  it ('does not append deprecated state to the rendered tag name', () => {
+    renderWithProviders (
+        <TagLink
+            tag={buildTag ({
+                name:         '旧タグ',
+                deprecatedAt: '2026-06-01T00:00:00.000Z',
+            })}
+            withWiki={false}
+            withCount={false}/>,
+    )
+
+    expect (screen.getByRole ('link', { name: '旧タグ' })).toBeInTheDocument ()
+    expect (screen.queryByText ('（廃止）')).not.toBeInTheDocument ()
+  })
+
   it ('links wiki markers to the correct detail route', () => {
     renderWithProviders (
         <TagLink tag={buildTag ({ hasWiki: true, name: 'a/b' })}/>,

frontend/src/components/TopNav.tsx

@@ -55,12 +55,6 @@ export const menuOutline = ({ tag, wikiId, user, pathName }: {
 	  { name: '追加', to: '/materials/new' },
 	  { name: '全体履歴', to: '/materials/changes', visible: false },
 	  { name: 'ヘルプ', to: '/wiki/ヘルプ:素材集' }] },
-      { name: '上映会', to: '/theatres/1', base: '/theatres', subMenu: [
-	  { name: <>第&thinsp;1&thinsp;会場</>, to: '/theatres/1' },
-	  { name: 'CyTube', to: '//cytube.mm428.net/r/deernijika' },
-	  { name: <>ニジカ放送局第&thinsp;1&thinsp;チャンネル</>,
-	    to: '//www.youtube.com/watch?v=DCU3hL4Uu6A' },
-	  { name: 'ヘルプ', to: '/wiki/ヘルプ:上映会' }] },
       { name: 'Wiki', to: '/wiki/ヘルプ:ホーム', base: '/wiki', subMenu: [
 	  { name: '検索', to: '/wiki' },
 	  { name: '新規', to: '/wiki/new' },
@@ -71,6 +65,9 @@ export const menuOutline = ({ tag, wikiId, user, pathName }: {
 	    visible: wikiPageFlg },
 	  { name: '履歴', to: `/wiki/changes?id=${ wikiId }`, visible: wikiPageFlg },
 	  { name: '編輯', to: `/wiki/${ wikiId || wikiTitle }/edit`, visible: wikiPageFlg }] },
+      { name: 'おたのしみ', visible: false, subMenu: [
+	  { name: '上映会 (β)', to: '/theatres/1' },
+	  { name: 'グカネータ (β)', to: '/gekanator' }] },
       { name: 'ユーザ', to: '/users/settings', visible: false, subMenu: [
 	  { name: '一覧', to: '/users', visible: false },
 	  { name: 'お前', to: `/users/${ user?.id }`, visible: false },
@@ -132,8 +129,12 @@ const TopNav: FC<Props> = ({ user }) => {
 
   const menu = menuOutline ({ tag, wikiId, user, pathName: location.pathname })
   const visibleMenu = menu.filter ((item): item is MenuVisibleItem => item.visible ?? true)
+  const moreMenu = menu.filter (item =>
+      !(item.visible ?? true)
+      || item.subMenu.filter (subItem => subItem.visible ?? true).length > 0)
   const activeIdx =
       visibleMenu.findIndex (item => location.pathname.startsWith (item.base || item.to))
+  const submenuHeight = moreVsbl ? 40 * moreMenu.length : (activeIdx < 0 ? 0 : 40)
 
   const prevActiveIdxRef = useRef<number> (activeIdx)
 
@@ -244,9 +245,9 @@ const TopNav: FC<Props> = ({ user }) => {
 	  <motion.div
 	      key="submenu-shell"
 	      layout
-	      className="relative hidden md:block overflow-hidden
+	      className="relative z-20 hidden md:block overflow-hidden
 			 bg-yellow-200 dark:bg-red-950"
-	      style={{ height: moreVsbl ? 40 * menu.length : (activeIdx < 0 ? 0 : 40) }}
+	      animate={{ height: submenuHeight }}
 	      onMouseLeave={() => {
 		if (moreVsbl)
 		  setMoreVsbl (false)
@@ -257,7 +258,7 @@ const TopNav: FC<Props> = ({ user }) => {
 	      }}>
 	  {moreVsbl
 	   ? (
-	      menu.map ((item, i) => (
+	      moreMenu.map ((item, i) => (
 		  <div key={i} className="relative h-[40px]">
 		    <div className="absolute inset-0 flex items-center px-3">
 		      <motion.div
@@ -267,7 +268,7 @@ const TopNav: FC<Props> = ({ user }) => {
 			       : { initial: { x: 40, y: -40, opacity: 0 },
 				   animate: { x: 0, y: 0, opacity: 1 },
 				   exit: { x: 40, y: -40, opacity: 0 } })}
-			  className="z-10 h-full flex items-center px-3 font-bold w-24">
+			  className="z-10 h-full flex items-center px-3 font-bold w-28">
 			<h2>{item.name}</h2>
 		      </motion.div>
 		      {item.subMenu

frontend/src/lib/api.ts

@@ -64,11 +64,14 @@ export const apiPatch = async <T> (
 ): Promise<T> => apiP ('patch', path, body, opt)
 
 
-export const apiDelete = async (
+export const apiDelete = async <T = void> (
     path: string,
     opt?: Opt,
-): Promise<void> => {
-  await client.delete (path, withUserCode (opt))
+): Promise<T> => {
+  const res = await client.delete (path, withUserCode (opt))
+  if (res.data == null || res.data === '')
+    return undefined as T
+  return toCamel (res.data as Record<string, unknown>, { deep: true }) as T
 }