backend/app/controllers/posts_controller.rb

@@ -131,6 +131,7 @@ class PostsController < ApplicationController
           title: nil,
           thumbnail_base: nil,
           tags: nil,
+          display_tags: [],
           original_created_from: nil,
           original_created_before: nil,
           duration: nil,
@@ -153,6 +154,7 @@ class PostsController < ApplicationController
         title: metadata[:title],
         thumbnail_base: metadata[:thumbnail_base],
         tags: metadata[:tags],
+        display_tags: metadata[:display_tags],
         original_created_from: metadata[:original_created_from],
         original_created_before: metadata[:original_created_before],
         duration: metadata[:duration],
@@ -173,6 +175,7 @@ class PostsController < ApplicationController
         title: nil,
         thumbnail_base: nil,
         tags: nil,
+        display_tags: [],
         original_created_from: nil,
         original_created_before: nil,
         duration: nil,
@@ -633,6 +636,7 @@ class PostsController < ApplicationController
         :title,
         :thumbnail_base,
         :tags,
+        :display_tags,
         :parent_post_ids,
         :original_created_from,
         :original_created_before,

backend/app/representations/post_compact_repr.rb

@@ -7,20 +7,13 @@ module PostCompactRepr
   def base post
     return nil if post.nil?
 
-    {
-        id: post.id,
-        title: post.title,
-        url: post.url,
-        thumbnail_url: thumbnail_url(post) }
-  end
-
-  def thumbnail_url post
-    return nil unless post.thumbnail.attached?
-
-    Rails.application.routes.url_helpers.rails_storage_proxy_url(
-        post.thumbnail,
-        only_path: false)
-  rescue ActionController::UrlGenerationError, ArgumentError, URI::InvalidURIError
-    nil
+    PostRepr
+        .common(post)
+        .slice(
+            'id',
+            'title',
+            'url',
+            'thumbnail',
+            'thumbnail_base')
   end
 end

backend/app/services/post_create_plan.rb

@@ -27,6 +27,7 @@ class PostCreatePlan
         original_created_from: @attributes[:original_created_from].presence,
         original_created_before: @attributes[:original_created_before].presence,
         tags: serialised_tags(direct_tag_specs, tag_sections),
+        display_tags: display_tags(direct_tag_specs, tag_sections),
         duration: @attributes[:duration].to_s,
         video_ms: video_ms,
         parent_post_ids: parent_post_ids.join(' '),
@@ -204,6 +205,15 @@ class PostCreatePlan
     }.sort.join(' ')
   end
 
+  def display_tags direct_tag_specs, tag_sections
+    direct_tag_specs.map { |spec|
+      {
+          name: spec[:name],
+          category: spec[:category].to_s,
+          section_literals: tag_sections[spec[:name]].to_a.map { Post.section_literal(_1) } }
+    }.sort_by { _1[:name] }
+  end
+
   def normalise_video_ms snapshot_tag_specs
     return nil unless snapshot_tag_specs.any? { _1[:name] == VIDEO_TAG_NAME }
 

backend/app/services/post_create_preflight.rb

@@ -29,6 +29,7 @@ class PostCreatePreflight
           original_created_before: preview[:attributes]['original_created_before'],
           duration: preview[:attributes]['duration'],
           video_ms: preview[:attributes]['video_ms'],
+          display_tags: preview[:display_tags] || [],
           field_warnings: final_field_warnings(preview[:field_warnings] || { }),
           base_warnings: preview[:base_warnings],
           existing_post_id: preview[:existing_post_id],
@@ -63,6 +64,7 @@ class PostCreatePreflight
         original_created_before: plan[:original_created_before],
         duration: plan[:duration],
         video_ms: plan[:video_ms],
+        display_tags: plan[:display_tags],
         direct_tag_specs: plan[:direct_tag_specs],
         default_tag_specs: plan[:default_tag_specs],
         snapshot_tag_specs: plan[:snapshot_tag_specs],

backend/app/services/post_metadata_fetcher.rb

@@ -32,6 +32,7 @@ class PostMetadataFetcher
       original_created_from: serialise_time(created_range&.first),
       original_created_before: serialise_time(created_range&.last),
       duration: serialise_duration(duration),
+      display_tags: display_tags(platform_tags),
       tags: platform_tags.join(' ') }
   end
 
@@ -42,6 +43,24 @@ class PostMetadataFetcher
     []
   end
 
+  def self.display_tags names
+    return [] if names.blank?
+
+    existing_tags =
+        Tag
+        .joins(:tag_name)
+        .where(tag_names: { name: names })
+        .index_by(&:name)
+
+    names.map { |name|
+      tag = existing_tags[name]
+      {
+          name: name,
+          category: (tag&.category || 'meta'),
+          section_literals: [] }
+    }
+  end
+
   def self.original_created_range value
     return nil if value.blank?
 
@@ -168,6 +187,7 @@ class PostMetadataFetcher
   end
 
   private_class_method :platform_tags,
+                       :display_tags,
                        :original_created_range,
                        :parse_timestamp_range,
                        :parse_nanoseconds,

frontend/src/components/TagLink.tsx

@@ -4,9 +4,13 @@ import { cn } from '@/lib/utils'
 
 import type { ComponentProps, CSSProperties, FC, HTMLAttributes } from 'react'
 
-import type { Tag } from '@/types'
+import type { Category, Tag } from '@/types'
 
-type CommonProps = { 
+type LightweightTag = {
+    name:     string
+    category: Category }
+
+type FullCommonProps = {
     tag:        Tag
     nestLevel?: number
     truncateOnMobile?: boolean
@@ -14,18 +18,43 @@ type CommonProps = {
     withCount?: boolean }
 
 type PropsWithLink =
-    & CommonProps
+    & FullCommonProps
     & { linkFlg?: true }
     & Partial<ComponentProps<typeof PrefetchLink>>
 
 type PropsWithoutLink =
-    & CommonProps
+    & FullCommonProps
     & { linkFlg: false }
     & Partial<HTMLAttributes<HTMLSpanElement>>
 
+type LightweightPropsWithLink =
+    & {
+	tag:              LightweightTag
+	nestLevel?:       number
+	truncateOnMobile?: boolean
+	withWiki:         false
+	withCount:        false
+	linkFlg?:         true }
+    & Partial<ComponentProps<typeof PrefetchLink>>
+
+type LightweightPropsWithoutLink =
+    & {
+	tag:              LightweightTag
+	nestLevel?:       number
+	truncateOnMobile?: boolean
+	withWiki:         false
+	withCount:        false
+	linkFlg:          false }
+    & Partial<HTMLAttributes<HTMLSpanElement>>
+
 type Props =
     | PropsWithLink
     | PropsWithoutLink
+    | LightweightPropsWithLink
+    | LightweightPropsWithoutLink
+
+const isFullTag = (tag: Tag | LightweightTag): tag is Tag =>
+    'id' in tag
 
 
 const TagLink: FC<Props> = ({ tag,
@@ -50,12 +79,13 @@ const TagLink: FC<Props> = ({ tag,
       'inline-flex min-w-0 max-w-full flex-nowrap items-stretch align-baseline gap-x-1 md:items-baseline'
   const markerWrapClass = 'shrink-0 self-start md:self-auto'
   const countClass = 'shrink-0 self-end md:self-auto'
+  const matchedAlias = isFullTag (tag) ? tag.matchedAlias : null
   const textTitle = title
-      ?? (tag.matchedAlias == null ? tag.name : `${ tag.matchedAlias } → ${ tag.name }`)
+      ?? (matchedAlias == null ? tag.name : `${ matchedAlias } → ${ tag.name }`)
 
   return (
       <span className={rootClass}>
-	{(linkFlg && withWiki) && (
+	{(linkFlg && withWiki && isFullTag (tag)) && (
 	    <span className={markerWrapClass}>
 	      {(tag.materialId != null || tag.hasWiki || tag.hasDeerjikists)
 	       ? (
@@ -118,7 +148,7 @@ const TagLink: FC<Props> = ({ tag,
 		style={{ paddingLeft: `${ (nestLevel - 1) }rem` }}>
 	      ↳
 	    </span>)}
-	{tag.matchedAlias != null && (
+	{matchedAlias != null && (
 	    <>
 	      <span
 		  title={textTitle}
@@ -126,7 +156,7 @@ const TagLink: FC<Props> = ({ tag,
 		  style={colourStyle}
 		  {...props}>
 		<ResponsiveMarqueeText
-		    text={tag.matchedAlias}
+		    text={matchedAlias}
 		    title={textTitle}
 		    truncateOnMobile={truncateOnMobile}/>
 	      </span>
@@ -156,7 +186,7 @@ const TagLink: FC<Props> = ({ tag,
 		  title={textTitle}
 		  truncateOnMobile={truncateOnMobile}/>
 	    </span>)}
-	{withCount && (
+	{(withCount && isFullTag (tag)) && (
 	    <span className={countClass}>{tag.postCount}</span>)}
       </span>)
 }

frontend/src/components/posts/import/PostImportRowSummary.tsx

@@ -1,4 +1,5 @@
 import FieldError from '@/components/common/FieldError'
+import PostImportTagLinks from '@/components/posts/import/PostImportTagLinks'
 import { Button } from '@/components/ui/button'
 import PostImportThumbnailPreview from '@/components/posts/import/PostImportThumbnailPreview'
 import PostImportStatusBadge from '@/components/posts/import/PostImportStatusBadge'
@@ -90,10 +91,7 @@ const PostImportRowSummary: FC<Props> = (
             <div className="truncate text-xs text-neutral-600 dark:text-neutral-300">
               {row.url}
             </div>
-            {String (row.attributes.tags ?? '') && (
-                <div className="truncate text-xs text-neutral-500 dark:text-neutral-400">
-                  {String (row.attributes.tags ?? '')}
-                </div>)}
+            <PostImportTagLinks tags={row.displayTags}/>
             <div className="text-xs text-neutral-500 dark:text-neutral-400">
               {summaryDate (row)}
             </div>
@@ -153,10 +151,7 @@ const PostImportRowSummary: FC<Props> = (
               <div className="flex flex-wrap gap-2">
                 {displayStatus != null && <PostImportStatusBadge value={displayStatus}/>}
               </div>
-              {String (row.attributes.tags ?? '') && (
-                  <div className="text-xs text-neutral-500 dark:text-neutral-400">
-                    {String (row.attributes.tags ?? '')}
-                  </div>)}
+              <PostImportTagLinks tags={row.displayTags}/>
               <div className="text-xs text-neutral-500 dark:text-neutral-400">
                 {summaryDate (row)}
               </div>

frontend/src/components/posts/import/PostImportTagLinks.tsx

@@ -0,0 +1,35 @@
+import TagLink from '@/components/TagLink'
+
+import type { FC } from 'react'
+
+import type { PostImportDisplayTag } from '@/lib/postImportTypes'
+
+type Props = {
+  tags: PostImportDisplayTag[] | undefined }
+
+const PostImportTagLinks: FC<Props> = ({ tags }) => {
+  if (tags == null || tags.length === 0)
+    return null
+
+  return (
+      <div className="flex flex-wrap gap-2">
+	{tags.map (tag => {
+	  const key = `${ tag.category }:${ tag.name }:${ tag.sectionLiterals?.join ('|') ?? '' }`
+	  return (
+	      <span key={key} className="inline-flex flex-nowrap items-baseline gap-1">
+		<TagLink
+		    tag={{
+			name: tag.name,
+			category: tag.category }}
+		    withWiki={false}
+		    withCount={false}/>
+		{tag.sectionLiterals?.map (literal => (
+		    <span key={literal} className="text-xs text-neutral-500 dark:text-neutral-400">
+		      {literal}
+		    </span>))}
+	      </span>)
+	})}
+      </div>)
+}
+
+export default PostImportTagLinks

frontend/src/lib/postImportRows.ts

@@ -68,6 +68,10 @@ export const validatableImportRows = (rows: PostImportRow[]): PostImportRow[] =>
 const buildResetSnapshot = (row: PostImportRow) => ({
     url: row.url,
     attributes: { ...row.attributes },
+    displayTags: row.displayTags?.map (tag => ({
+	name: tag.name,
+	category: tag.category,
+	sectionLiterals: tag.sectionLiterals == null ? undefined : [...tag.sectionLiterals] })) ?? [],
     provenance: { ...row.provenance },
     tagSources: {
 	automatic: row.tagSources?.automatic ?? '',
@@ -243,6 +247,11 @@ export const buildNextEditedRow = (
 	...editingRow,
 	url: draft.url,
 	attributes: nextAttributes,
+	displayTags:
+	    editingRow.displayTags?.map (tag => ({
+		name: tag.name,
+		category: tag.category,
+		sectionLiterals: tag.sectionLiterals == null ? undefined : [...tag.sectionLiterals] })),
 	thumbnailFile: draft.thumbnailFile,
 	provenance: {
 	    ...nextProvenance,
@@ -316,6 +325,12 @@ export const mergeValidatedImportRows = (
           ...previous,
           url: row.url,
           attributes: row.attributes,
+          displayTags:
+              row.displayTags?.map (tag => ({
+                  name: tag.name,
+                  category: tag.category,
+                  sectionLiterals:
+                      tag.sectionLiterals == null ? undefined : [...tag.sectionLiterals] })),
           provenance: row.provenance,
           tagSources: row.tagSources,
           skipReason: row.skipReason,

frontend/src/lib/postImportStorage.ts

@@ -1,4 +1,5 @@
 import type { PostImportOrigin,
+	      PostImportDisplayTag,
 	      PostImportExistingPost,
 	      PostImportResetSnapshot,
 	      PostImportRow,
@@ -43,6 +44,7 @@ const ROW_KEYS = [
     'existingPostId',
     'existingPost',
     'metadataUrl',
+    'displayTags',
     'resetSnapshot',
     'createdPostId',
     'importStatus',
@@ -216,11 +218,53 @@ const hasOnlyKeys = (
 ): boolean =>
     Object.keys (value).every (key => allowedKeys.includes (key))
 
+const sanitiseDisplayTag = (value: unknown): PostImportDisplayTag | null => {
+    if (!(isPlainObject (value)))
+      return null
+    if (!(hasOnlyKeys (value, ['name', 'category', 'sectionLiterals'])))
+      return null
+    if (typeof value.name !== 'string' || value.name === '')
+      return null
+    if (typeof value.category !== 'string')
+      return null
+    if (!(['deerjikist',
+	   'meme',
+	   'character',
+	   'general',
+	   'material',
+	   'meta',
+	   'nico'] as const).includes (value.category as never))
+      return null
+    if (value.sectionLiterals != null
+        && (!(Array.isArray (value.sectionLiterals))
+            || !(value.sectionLiterals.every (entry => typeof entry === 'string'))))
+      return null
+
+    return {
+        name: value.name,
+        category: value.category,
+        sectionLiterals:
+            value.sectionLiterals == null
+            ? undefined
+            : [...value.sectionLiterals] }
+}
+
+const sanitiseDisplayTags = (value: unknown): PostImportDisplayTag[] | null => {
+    if (value == null)
+      return []
+    if (!(Array.isArray (value)))
+      return null
+
+    const tags = value.map (sanitiseDisplayTag)
+    return tags.some (tag => tag == null) ? null : (tags as PostImportDisplayTag[])
+}
+
 const sanitiseResetSnapshot = (value: unknown): PostImportResetSnapshot | null => {
     if (!(isPlainObject (value)))
       return null
     if (!(hasOnlyKeys (value, ['url',
 			       'attributes',
+			       'displayTags',
 			       'provenance',
 			       'tagSources',
 			       'fieldWarnings',
@@ -258,10 +302,14 @@ const sanitiseResetSnapshot = (value: unknown): PostImportResetSnapshot | null =
       return null
     if (value.metadataUrl != null && typeof value.metadataUrl !== 'string')
       return null
+    const displayTags = sanitiseDisplayTags (value.displayTags)
+    if (displayTags == null)
+      return null
 
     return {
         url: value.url,
         attributes: value.attributes as Record<string, string | number>,
+        displayTags,
         provenance: value.provenance as Record<string, PostImportOrigin>,
         tagSources: value.tagSources as Record<PostImportOrigin, string>,
         fieldWarnings,
@@ -278,14 +326,39 @@ const sanitiseExistingPost = (value: unknown): PostImportExistingPost | undefine
       return undefined
     if (typeof value.title !== 'string' || typeof value.url !== 'string')
       return undefined
-    if (value.thumbnailUrl != null && typeof value.thumbnailUrl !== 'string')
+    if (value.thumbnail !== undefined
+        && value.thumbnail !== null
+        && typeof value.thumbnail !== 'string')
+      return undefined
+    if (value.thumbnailBase !== undefined
+        && value.thumbnailBase !== null
+        && typeof value.thumbnailBase !== 'string')
+      return undefined
+    if (value.thumbnailUrl !== undefined
+        && value.thumbnailUrl !== null
+        && typeof value.thumbnailUrl !== 'string')
       return undefined
 
     return {
         id: Number (value.id),
         title: value.title,
         url: value.url,
-        thumbnailUrl: value.thumbnailUrl as string | undefined }
+        thumbnail:
+            value.thumbnail === null
+            ? null
+            : typeof value.thumbnail === 'string'
+            ? value.thumbnail
+            : value.thumbnailUrl === null
+              ? null
+              : typeof value.thumbnailUrl === 'string'
+              ? value.thumbnailUrl
+              : undefined,
+        thumbnailBase:
+            value.thumbnailBase === null
+            ? null
+            : typeof value.thumbnailBase === 'string'
+            ? value.thumbnailBase
+            : undefined }
 }
 
 const canonicalisePersistedRow = (
@@ -319,12 +392,18 @@ const serialiseExistingPost = (value: PostImportExistingPost | undefined) =>
 	 id: value.id,
 	 title: value.title,
 	 url: value.url,
-	 thumbnailUrl: value.thumbnailUrl }
+	 thumbnail: value.thumbnail,
+	 thumbnailBase: value.thumbnailBase }
 
 const serialiseResetSnapshot = (value: PostImportResetSnapshot) => ({
     url: value.url,
     attributes: Object.fromEntries (
 	Object.entries (value.attributes).map (([key, entry]) => [key, entry])),
+    displayTags: value.displayTags.map (tag => ({
+	name: tag.name,
+	category: tag.category,
+	sectionLiterals:
+	    tag.sectionLiterals == null ? undefined : [...tag.sectionLiterals] })),
     provenance: Object.fromEntries (
 	Object.entries (value.provenance).map (([key, entry]) => [key, entry])),
     tagSources: {
@@ -366,6 +445,12 @@ export const serialisePostImportRow = (row: PostImportRow) => {
 		Object.entries (row.importErrors).map (([key, entry]) => [key, [...entry]])),
 	provenance: Object.fromEntries (
 	    Object.entries (row.provenance).map (([key, entry]) => [key, entry])),
+	displayTags:
+	    row.displayTags?.map (tag => ({
+		name: tag.name,
+		category: tag.category,
+		sectionLiterals:
+		    tag.sectionLiterals == null ? undefined : [...tag.sectionLiterals] })) ?? [],
 	tagSources:
 	    row.tagSources == null
 	    ? undefined
@@ -475,6 +560,9 @@ const sanitiseRow = (value: unknown): PostImportRow | null => {
         if (!(Object.values (value.tagSources).every (entry => typeof entry === 'string')))
           return null
       }
+    const displayTags = sanitiseDisplayTags (value.displayTags)
+    if (displayTags == null)
+      return null
 
     const existingPost = sanitiseExistingPost (value.existingPost)
     const existingPostId =
@@ -496,6 +584,7 @@ const sanitiseRow = (value: unknown): PostImportRow | null => {
             ? importErrors
             : undefined,
         provenance: value.provenance as Record<string, PostImportOrigin>,
+        displayTags,
         tagSources: value.tagSources as Record<PostImportOrigin, string> | undefined,
         status: value.status,
         skipReason: value.skipReason ?? undefined,

frontend/src/lib/postImportTypes.ts

@@ -1,3 +1,5 @@
+import type { Category } from '@/types'
+
 export type PostImportOrigin = 'automatic' | 'manual'
 export type PostImportRepairMode = 'all' | 'failed'
 export type PostImportStatus =
@@ -9,9 +11,15 @@ export type PostImportSkipReason = 'existing' | 'manual'
 export type PostImportResultStatus = 'created' | 'skipped' | 'failed'
 export type PostImportAttributeValue = string | number
 
+export type PostImportDisplayTag = {
+    name:            string
+    category:        Category
+    sectionLiterals?: string[] }
+
 export type PostImportResetSnapshot = {
     url:         string
     attributes:  Record<string, PostImportAttributeValue>
+    displayTags: PostImportDisplayTag[]
     provenance:  Record<string, PostImportOrigin>
     tagSources:  Record<PostImportOrigin, string>
     fieldWarnings: Record<string, string[]>
@@ -22,7 +30,8 @@ export type PostImportExistingPost = {
     id:            number
     title:         string
     url:           string
-    thumbnailUrl?: string }
+    thumbnail?:    string | null
+    thumbnailBase?: string | null }
 
 export type PostImportRow = {
     sourceRow:         number
@@ -39,6 +48,7 @@ export type PostImportRow = {
     existingPostId?:   number
     existingPost?:     PostImportExistingPost
     metadataUrl?:      string
+    displayTags?:      PostImportDisplayTag[]
     resetSnapshot:     PostImportResetSnapshot
     createdPostId?:    number
     importStatus?:     PostImportStatus

frontend/src/lib/postNewQueryState.ts

@@ -1,7 +1,9 @@
+import { CATEGORIES } from '@/consts'
 import { resultRepairMode } from '@/lib/postImportRows'
 import { validatePostImportSessionId } from '@/lib/postImportStorage'
 
 import type {
+    PostImportDisplayTag,
     PostImportOrigin,
     PostImportRepairMode,
     PostImportRow,
@@ -18,9 +20,11 @@ type QueryRowState = {
   duration:                string
   tags:                    string
   parent_post_ids:         string
+  display_tags:            PostImportDisplayTag[]
   manual:                  string[]
   skip:                    PostImportSkipReason | null
   existing_post_id:        number | null
+  existing_post:           PostImportRow['existingPost'] | null
   import_status:           PostImportRow['importStatus'] | null
   created_post_id:         number | null
   recoverable:             boolean | null }
@@ -45,9 +49,11 @@ type EncodedRowState = {
   d?: string
   g?: string
   p?: string
+  k?: EncodedDisplayTag[]
   m?: string[]
   s?: EncodedSkip
   e?: number
+  o?: EncodedExistingPost
   i?: EncodedImportStatus
   c?: number
   r?: boolean }
@@ -56,6 +62,18 @@ type EncodedState = {
   v:    1
   rows: EncodedRowState[] }
 
+type EncodedDisplayTag = {
+  n:  string
+  c:  PostImportDisplayTag['category']
+  s?: string[] }
+
+type EncodedExistingPost = {
+  i:  number
+  t:  string
+  u:  string
+  h?: string | null
+  b?: string | null }
+
 export type ParsedPostNewState = {
   rows:       PostImportRow[]
   source:     string
@@ -77,9 +95,11 @@ const BASIC_KEYS = [
     'tags',
     'parent_post_ids'] as const
 const STATE_KEYS = [
+    'display_tags',
     'manual',
     'skip',
     'existing_post_id',
+    'existing_post',
     'import_status',
     'created_post_id',
     'recoverable'] as const
@@ -95,9 +115,11 @@ const ENCODED_ROW_KEYS = [
     'd',
     'g',
     'p',
+    'k',
     'm',
     's',
     'e',
+    'o',
     'i',
     'c',
     'r'] as const
@@ -200,6 +222,153 @@ const decodeImportStatus = (
   return null
 }
 
+const sanitiseDisplayTag = (value: unknown): PostImportDisplayTag | null => {
+  if (!(isPlainObject (value)))
+    return null
+  if (!(hasOnlyKeys (value, ['n', 'c', 's'])))
+    return null
+  if (typeof value.n !== 'string' || value.n === '')
+    return null
+  if (!(CATEGORIES.includes (value.c as never)))
+    return null
+  if (value.s != null && !(Array.isArray (value.s)) || !(value.s ?? []).every (entry => typeof entry === 'string'))
+    return null
+
+  return {
+      name: value.n,
+      category: value.c,
+      sectionLiterals: value.s == null ? undefined : [...value.s] }
+}
+
+const sanitiseDisplayTags = (
+    value: unknown,
+): PostImportDisplayTag[] | null => {
+  if (value == null)
+    return []
+  if (!(Array.isArray (value)))
+    return null
+
+  const tags = value.map (sanitiseDisplayTag)
+  return tags.some (tag => tag == null) ? null : (tags as PostImportDisplayTag[])
+}
+
+const encodeDisplayTags = (
+    tags: PostImportDisplayTag[] | undefined,
+): EncodedDisplayTag[] | undefined =>
+    tags == null || tags.length === 0
+    ? undefined
+    : tags.map (tag => ({
+	n: tag.name,
+	c: tag.category,
+	s:
+	    tag.sectionLiterals == null || tag.sectionLiterals.length === 0
+	    ? undefined
+	    : [...tag.sectionLiterals] }))
+
+const encodeDisplayTagsParam = (
+    tags: PostImportDisplayTag[] | undefined,
+): string | null => {
+  const encodedTags = encodeDisplayTags (tags)
+  if (encodedTags == null)
+    return null
+
+  return encodeBase64UrlBytes (textEncoder.encode (JSON.stringify (encodedTags)))
+}
+
+const decodeDisplayTagsParam = (
+    value: string | null,
+): PostImportDisplayTag[] | null => {
+  if (value == null || value === '')
+    return []
+
+  const bytes = decodeBase64UrlBytes (value)
+  if (bytes == null || bytes.byteLength > MAX_DECOMPRESSED_STATE_BYTES)
+    return null
+
+  try
+  {
+    return sanitiseDisplayTags (JSON.parse (textDecoder.decode (bytes)))
+  }
+  catch
+  {
+    return null
+  }
+}
+
+
+const sanitiseExistingPost = (
+    value: unknown,
+): PostImportRow['existingPost'] | null => {
+  if (value == null)
+    return null
+  if (!(isPlainObject (value)))
+    return null
+  if (!(hasOnlyKeys (value, ['i', 't', 'u', 'h', 'b'])))
+    return null
+  if (!(typeof value.i === 'number'
+        && Number.isSafeInteger (value.i)
+        && value.i > 0))
+    return null
+  if (typeof value.t !== 'string' || typeof value.u !== 'string')
+    return null
+  if (value.h != null && typeof value.h !== 'string')
+    return null
+  if (value.b != null && typeof value.b !== 'string')
+    return null
+
+  return {
+      id: value.i,
+      title: value.t,
+      url: value.u,
+      thumbnail: value.h,
+      thumbnailBase: value.b }
+}
+
+
+const encodeExistingPost = (
+    post: PostImportRow['existingPost'] | undefined,
+): EncodedExistingPost | undefined =>
+    post == null
+    ? undefined
+    : {
+	i: post.id,
+	t: post.title,
+	u: post.url,
+	h: post.thumbnail,
+	b: post.thumbnailBase }
+
+
+const encodeExistingPostParam = (
+    post: PostImportRow['existingPost'] | undefined,
+): string | null => {
+  const encodedPost = encodeExistingPost (post)
+  if (encodedPost == null)
+    return null
+
+  return encodeBase64UrlBytes (textEncoder.encode (JSON.stringify (encodedPost)))
+}
+
+
+const decodeExistingPostParam = (
+    value: string | null,
+): PostImportRow['existingPost'] | null => {
+  if (value == null || value === '')
+    return null
+
+  const bytes = decodeBase64UrlBytes (value)
+  if (bytes == null || bytes.byteLength > MAX_DECOMPRESSED_STATE_BYTES)
+    return null
+
+  try
+  {
+    return sanitiseExistingPost (JSON.parse (textDecoder.decode (bytes)))
+  }
+  catch
+  {
+    return null
+  }
+}
+
 
 const isStrictPositiveIntegerString = (value: string): boolean =>
     /^[1-9][0-9]*$/.test (value)
@@ -338,9 +507,11 @@ const baseRowState = (row: PostImportRow): QueryRowState => ({
     duration: String (row.attributes.duration ?? ''),
     tags: String (row.attributes.tags ?? ''),
     parent_post_ids: String (row.attributes.parentPostIds ?? ''),
+    display_tags: row.displayTags ?? [],
     manual: manualFields (row),
     skip: row.skipReason ?? null,
     existing_post_id: row.existingPostId ?? null,
+    existing_post: row.existingPost ?? null,
     import_status: row.importStatus ?? null,
     created_post_id: row.createdPostId ?? null,
     recoverable: row.recoverable ?? null })
@@ -379,13 +550,36 @@ const buildRow = (state: FullRowState): PostImportRow => {
       baseWarnings: [],
       validationErrors: { },
       provenance,
+      displayTags: state.display_tags.map (tag => ({
+	  name: tag.name,
+	  category: tag.category,
+	  sectionLiterals:
+	      tag.sectionLiterals == null
+	      ? undefined
+	      : [...tag.sectionLiterals] })),
       tagSources,
       status: 'pending',
       skipReason: state.skip ?? undefined,
       existingPostId: state.existing_post_id ?? undefined,
+      existingPost:
+	  state.existing_post == null
+	  ? undefined
+	  : {
+	      id: state.existing_post.id,
+	      title: state.existing_post.title,
+	      url: state.existing_post.url,
+	      thumbnail: state.existing_post.thumbnail,
+	      thumbnailBase: state.existing_post.thumbnailBase },
       resetSnapshot: {
 	  url: state.url,
 	  attributes: { ...attributes },
+	  displayTags: state.display_tags.map (tag => ({
+	      name: tag.name,
+	      category: tag.category,
+	      sectionLiterals:
+		  tag.sectionLiterals == null
+		  ? undefined
+		  : [...tag.sectionLiterals] })),
 	  provenance: { ...provenance },
 	  tagSources: { ...tagSources },
 	  fieldWarnings: { },
@@ -429,6 +623,8 @@ const parseEncodedRow = (
   const createdPostId = row['c']
   const recoverable = row['r']
   const sourceRow = row['n']
+  const displayTags = sanitiseDisplayTags (row['k'])
+  const existingPost = sanitiseExistingPost (row['o'])
 
   if (requireUrl && typeof url !== 'string')
     return null
@@ -454,6 +650,10 @@ const parseEncodedRow = (
     return null
   if (recoverable != null && typeof recoverable !== 'boolean')
     return null
+  if (displayTags == null)
+    return null
+  if (row['o'] != null && existingPost == null)
+    return null
   if (sourceRow != null
       && !(typeof sourceRow === 'number'
            && Number.isSafeInteger (sourceRow)
@@ -461,6 +661,8 @@ const parseEncodedRow = (
     return null
   if (skip === 'existing' && existingPostId == null)
     return null
+  if (existingPost != null && existingPost.id !== existingPostId)
+    return null
   if (importStatus === 'created' && createdPostId == null)
     return null
   if (importStatus !== 'created' && createdPostId != null)
@@ -512,9 +714,11 @@ const parseEncodedRow = (
       duration: parsedStrings.duration,
       tags: parsedStrings.tags,
       parent_post_ids: parsedStrings.parent_post_ids,
+      display_tags: displayTags,
       manual: manual ?? [],
       skip,
       existing_post_id: existingPostId ?? null,
+      existing_post: existingPost,
       import_status: importStatus,
       created_post_id: createdPostId ?? null,
       recoverable: recoverable ?? null }
@@ -543,9 +747,11 @@ const parseSingleRow = (params: URLSearchParams): ParsedPostNewState | null => {
 	  duration: '',
 	  tags: '',
 	  parent_post_ids: '',
+	  display_tags: [],
 	  manual: [],
 	  skip: null,
 	  existing_post_id: null,
+	  existing_post: null,
 	  import_status: null,
 	  created_post_id: null,
 	  recoverable: null })
@@ -580,14 +786,22 @@ const parseSingleRow = (params: URLSearchParams): ParsedPostNewState | null => {
     return null
   const existingPostIdValue = params.get ('existing_post_id')
   const createdPostIdValue = params.get ('created_post_id')
+  const displayTags = decodeDisplayTagsParam (params.get ('display_tags'))
+  const existingPost = decodeExistingPostParam (params.get ('existing_post'))
   const existingPostId = parsePositiveInt (existingPostIdValue)
   const createdPostId = parsePositiveInt (createdPostIdValue)
+  if (displayTags == null)
+    return null
+  if (params.get ('existing_post') != null && existingPost == null)
+    return null
   if (existingPostIdValue != null && existingPostId == null)
     return null
   if (createdPostIdValue != null && createdPostId == null)
     return null
   if (skipValue === 'existing' && existingPostId == null)
     return null
+  if (existingPost != null && existingPost.id !== existingPostId)
+    return null
   if (importStatus === 'created' && createdPostId == null)
     return null
   if (importStatus !== 'created' && createdPostIdValue != null)
@@ -608,9 +822,11 @@ const parseSingleRow = (params: URLSearchParams): ParsedPostNewState | null => {
       duration: params.get ('duration') ?? '',
       tags: params.get ('tags') ?? '',
       parent_post_ids: params.get ('parent_post_ids') ?? '',
+      display_tags: displayTags,
       manual: parseManual (params.get ('manual')),
       skip: skipValue,
       existing_post_id: existingPostId,
+      existing_post: existingPost,
       import_status: importStatus,
       created_post_id: createdPostId,
       recoverable })
@@ -727,6 +943,12 @@ const regularQuery = (rows: PostImportRow[]): URLSearchParams => {
       params.set ('duration', String (row?.attributes.duration ?? ''))
       params.set ('tags', String (row?.attributes.tags ?? ''))
       params.set ('parent_post_ids', String (row?.attributes.parentPostIds ?? ''))
+      const displayTags = encodeDisplayTagsParam (row?.displayTags)
+      if (displayTags != null)
+	params.set ('display_tags', displayTags)
+      const existingPost = encodeExistingPostParam (row?.existingPost)
+      if (existingPost != null)
+	params.set ('existing_post', existingPost)
       const manual = manualFields (row).join (',')
       if (manual !== '')
 	params.set ('manual', manual)
@@ -776,12 +998,16 @@ const encodeRowState = (
     encoded.g = base.tags
   if (base.parent_post_ids !== '')
     encoded.p = base.parent_post_ids
+  if (base.display_tags.length > 0)
+    encoded.k = encodeDisplayTags (base.display_tags)
   if (base.manual.length > 0)
     encoded.m = [...base.manual]
   if (base.skip != null)
     encoded.s = encodeSkip (base.skip)
   if (base.existing_post_id != null)
     encoded.e = base.existing_post_id
+  if (base.existing_post != null)
+    encoded.o = encodeExistingPost (base.existing_post)
   if (base.import_status != null)
     encoded.i = encodeImportStatus (base.import_status)
   if (base.created_post_id != null)

frontend/src/pages/posts/PostImportReviewPage.tsx

@@ -74,6 +74,7 @@ type PostMetadataResponse = {
   duration?:             string
   videoMs?:              number
   tags?:                 string
+  displayTags?:          PostImportRow['displayTags']
   fieldWarnings?:        Record<string, string[]>
   baseWarnings?:         string[]
   validationErrors?:     Record<string, string[]>
@@ -82,7 +83,8 @@ type PostMetadataResponse = {
     id:           number
     title:        string
     url:          string
-    thumbnailUrl?: string } | null }
+    thumbnail?:   string | null
+    thumbnailBase?: string | null } | null }
 
 type BulkApiRow = {
   status:        'created' | 'skipped' | 'failed'
@@ -92,7 +94,8 @@ type BulkApiRow = {
     id:           number
     title:        string
     url:          string
-    thumbnailUrl?: string } | null
+    thumbnail?:   string | null
+    thumbnailBase?: string | null } | null
   fieldWarnings?: Record<string, string[]>
   baseWarnings?: string[]
   errors?:       Record<string, string[]>
@@ -238,6 +241,14 @@ const mergeDryRunRow = (
             videoMs: result.videoMs ?? '',
             tags: result.tags ?? '',
             parentPostIds: String (result.parentPostIds ?? currentRow.attributes.parentPostIds ?? '') },
+        displayTags:
+            result.displayTags?.map (tag => ({
+                name: tag.name,
+                category: tag.category,
+                sectionLiterals:
+                    tag.sectionLiterals == null
+                    ? undefined
+                    : [...tag.sectionLiterals] })) ?? [],
         fieldWarnings,
         baseWarnings: result.baseWarnings ?? [],
         validationErrors: { },
@@ -273,6 +284,14 @@ const buildPreviewResetSnapshot = (
 	videoMs: preview.videoMs ?? '',
 	tags: preview.tags ?? '',
 	parentPostIds: String (preview.parentPostIds ?? '') },
+    displayTags:
+	preview.displayTags?.map (tag => ({
+	    name: tag.name,
+	    category: tag.category,
+	    sectionLiterals:
+		tag.sectionLiterals == null
+		? undefined
+		: [...tag.sectionLiterals] })) ?? [],
     provenance: {
 	url: 'manual',
 	title: 'automatic',
@@ -368,6 +387,14 @@ const mergePreviewRow = (
       ...currentRow,
       attributes: { ...currentRow.attributes },
       provenance: { ...currentRow.provenance },
+      displayTags:
+	  currentRow.displayTags?.map (tag => ({
+	      name: tag.name,
+	      category: tag.category,
+	      sectionLiterals:
+		  tag.sectionLiterals == null
+		  ? undefined
+		  : [...tag.sectionLiterals] })) ?? [],
       tagSources: {
 	  automatic: currentRow.tagSources?.automatic ?? '',
 	  manual: currentRow.tagSources?.manual ?? '' },
@@ -406,6 +433,14 @@ const mergePreviewRow = (
   if (currentRow.provenance.tags !== 'manual')
     {
       nextRow.attributes.tags = preview.tags ?? ''
+      nextRow.displayTags =
+	  preview.displayTags?.map (tag => ({
+	      name: tag.name,
+	      category: tag.category,
+	      sectionLiterals:
+		  tag.sectionLiterals == null
+		  ? undefined
+		  : [...tag.sectionLiterals] })) ?? []
     }
   nextRow.tagSources.automatic = preview.tags ?? ''
   if (currentRow.provenance.parentPostIds !== 'manual')
@@ -459,7 +494,7 @@ const ExistingSkippedRows: FC<ExistingSkippedRowsProps> = ({ id, rows }) => {
 		    rel="noopener noreferrer"
 		    className="flex items-center gap-3 p-3">
 		  <PostThumbnailPreview
-		      url={post.thumbnailUrl ?? ''}
+		      url={post.thumbnail || post.thumbnailBase || ''}
 		      className="h-10 w-10 shrink-0"/>
 		  <div className="min-w-0 flex-1">
 		    <div className="truncate text-sm font-medium">
@@ -809,6 +844,14 @@ const PostImportReviewPage: FC<Props> = ({ user }) => {
 	? { ...currentRow,
 	    url: currentRow.resetSnapshot.url,
 	    attributes: { ...currentRow.resetSnapshot.attributes },
+	    displayTags:
+		currentRow.resetSnapshot.displayTags.map (tag => ({
+		    name: tag.name,
+		    category: tag.category,
+		    sectionLiterals:
+			tag.sectionLiterals == null
+			? undefined
+			: [...tag.sectionLiterals] })),
 	    provenance: { ...currentRow.resetSnapshot.provenance },
 	    tagSources: { ...currentRow.resetSnapshot.tagSources },
 	    fieldWarnings: Object.fromEntries (

frontend/src/pages/posts/PostImportSourcePage.tsx

@@ -76,6 +76,7 @@ const buildInitialRows = (source: string): PostImportRow[] =>
                 automatic: '',
                 manual: '' },
             status: 'pending' as const,
+            displayTags: [],
             resetSnapshot: {
                 url: row.url,
                 attributes: {
@@ -100,6 +101,7 @@ const buildInitialRows = (source: string): PostImportRow[] =>
                 tagSources: {
                     automatic: '',
                     manual: '' },
+                displayTags: [],
                 fieldWarnings: { },
                 baseWarnings: [] } }))