#378

Reviewed-on: #377
Co-authored-by: miteruzo <miteruzo@naver.com>
Co-committed-by: miteruzo <miteruzo@naver.com>

AGENTS.md

@@ -107,11 +107,16 @@ npm run preview
 - 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`.
+- 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 `]`.
@@ -125,6 +130,64 @@ npm run preview
 - 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
@@ -158,6 +221,13 @@ npm run preview
 - 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
 
@@ -179,6 +249,9 @@ npm run preview
   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:
 

backend/AGENTS.md

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

backend/app/controllers/gekanator_games_controller.rb

@@ -1,6 +1,6 @@
 class GekanatorGamesController < ApplicationController
   def create
-    return head :not_found unless current_user&.admin?
+    return head :unauthorized unless current_user
 
     guessed_post_id = params.require(:guessed_post_id)
     correct_post_id = params[:correct_post_id].presence
@@ -14,10 +14,259 @@ class GekanatorGamesController < ApplicationController
         question_count: answers.length,
         answers:)
 
-    if game.save
-      render json: { id: game.id }, status: :created
-    else
+    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/posts_controller.rb

@@ -148,10 +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)
@@ -165,6 +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
@@ -255,6 +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
@@ -378,7 +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)
@@ -501,7 +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:,
@@ -533,9 +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:,
@@ -622,13 +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
 
@@ -332,6 +348,93 @@ 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

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

@@ -2,6 +2,12 @@ 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 }

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/post.rb

@@ -7,6 +7,8 @@ class Post < ApplicationRecord
   has_many :active_post_tags, -> { kept }, class_name: 'PostTag', inverse_of: :post
   has_many :post_tags_with_discarded, -> { with_discarded }, class_name: 'PostTag'
   has_many :tags, through: :active_post_tags
+  has_many :active_tags, -> { where(tags: { deprecated_at: nil }) },
+           through: :active_post_tags, source: :tag
 
   has_many :user_post_views, dependent: :delete_all
   has_many :post_similarities, dependent: :delete_all
@@ -19,8 +21,9 @@ class Post < ApplicationRecord
   has_many :gekanator_correct_games,
            class_name: 'GekanatorGame',
            foreign_key: :correct_post_id,
-           dependent: :nullify,
+           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 }
 
@@ -77,6 +87,8 @@ class Tag < ApplicationRecord
     (self.tag_name ||= build_tag_name).name = val
   end
 
+  def deprecated? = deprecated_at?
+
   def has_wiki = wiki_page.present?
 
   def material_id = materials.first&.id
@@ -92,7 +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/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/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/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/config/routes.rb

@@ -64,7 +64,21 @@ Rails.application.routes.draw do
   end
 
   namespace :gekanator do
-    resources :games, only: [:create], controller: '/gekanator_games'
+    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

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/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2026_06_07_000000) do
+ActiveRecord::Schema[8.0].define(version: 2026_06_21_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 +48,18 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_07_000000) 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
@@ -63,6 +75,52 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_07_000000) do
     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"
@@ -261,6 +319,7 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_07_000000) 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
@@ -278,10 +337,13 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_07_000000) 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
 
@@ -493,9 +555,18 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_07_000000) 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_versions", "materials"
   add_foreign_key "material_versions", "materials", column: "parent_id"
   add_foreign_key "material_versions", "tags"

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/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

@@ -52,16 +52,16 @@ RSpec.describe 'Gekanator games API', type: :request do
       expect(response).to have_http_status(:unprocessable_entity)
     end
 
-    it 'returns not found without an admin user' do
+    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(:not_found)
+      expect(response).to have_http_status(:unauthorized)
     end
 
-    it 'returns not found for a non-admin user' do
+    it 'stores a game for a non-admin user' do
       sign_in_as user
 
       post '/gekanator/games', params: {
@@ -69,7 +69,8 @@ RSpec.describe 'Gekanator games API', type: :request do
           correct_post_id: guessed_post.id,
           answers: [{ question_id: 'tag:1', answer: 'yes' }] }
 
-      expect(response).to have_http_status(:not_found)
+      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/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/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/src/App.tsx

@@ -40,7 +40,7 @@ import WikiHistoryPage from '@/pages/wiki/WikiHistoryPage'
 import WikiNewPage from '@/pages/wiki/WikiNewPage'
 import WikiSearchPage from '@/pages/wiki/WikiSearchPage'
 
-import type { Dispatch, FC, ReactNode, SetStateAction } from 'react'
+import type { Dispatch, FC, SetStateAction } from 'react'
 
 import type { User } from '@/types'
 
@@ -81,10 +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={
-	      <AdminOnly user={user}>
-		<GekanatorPage/>
-	      </AdminOnly>}/>
+	  <Route path="/gekanator" element={<GekanatorPage user={user}/>}/>
 	  <Route path="/more" element={<MorePage/>}/>
 	  <Route path="*" element={<NotFound/>}/>
 	</Routes>
@@ -92,16 +89,6 @@ const RouteTransitionWrapper = ({ user, setUser }: {
 }
 
 
-const AdminOnly = ({ user, children }: {
-    user:      User | null
-    children:  ReactNode }) => {
-  if (user?.role !== 'admin')
-    return <NotFound/>
-
-  return <>{children}</>
-}
-
-
 const PostDetailRoute = ({ user }: { user: User | null }) => {
   const location = useLocation ()
   const key = location.pathname

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/TagLink.tsx

@@ -128,4 +128,4 @@ const TagLink: FC<Props> = ({ tag,
       </>)
 }
 
-export default TagLink
+export default TagLink

frontend/src/components/TopNav.tsx

@@ -66,7 +66,8 @@ export const menuOutline = ({ tag, wikiId, user, pathName }: {
 	  { 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: '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 },

frontend/src/lib/gekanator.test.ts

@@ -0,0 +1,523 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+import { apiGet, apiPost } from '@/lib/api'
+import {
+  buildGekanatorQuestions,
+  expectedAnswerForQuestion,
+  fetchGekanatorPosts,
+  fetchGekanatorQuestions,
+  learnedSemanticSideForPost,
+  questionIdForCondition,
+  restoreGekanatorQuestion,
+  saveGekanatorExtraQuestionAnswers,
+  saveGekanatorGame,
+  saveGekanatorQuestionSuggestion,
+} from '@/lib/gekanator'
+
+import type {
+  GekanatorAnswerLog,
+  StoredGekanatorQuestion,
+} from '@/lib/gekanator'
+import type { Post } from '@/types'
+
+vi.mock('@/lib/api', () => ({
+  apiGet: vi.fn(),
+  apiPost: vi.fn(),
+}))
+
+const mockedApiPost = vi.mocked(apiPost)
+const mockedApiGet = vi.mocked(apiGet)
+
+const post = (overrides: Partial<Post> = {}): Post => ({
+  id: 1,
+  versionNo: 1,
+  url: 'https://example.com/posts/1',
+  title: 'post title',
+  thumbnail: null,
+  thumbnailBase: null,
+  tags: [],
+  viewed: false,
+  related: [],
+  originalCreatedFrom: null,
+  originalCreatedBefore: null,
+  createdAt: '2026-06-10T00:00:00.000Z',
+  updatedAt: '2026-06-10T00:00:00.000Z',
+  uploadedUser: null,
+  ...overrides,
+})
+
+describe('Gekanator API functions', () => {
+  it('returns posts from the Gekanator posts endpoint', async () => {
+    const posts = [post()]
+    mockedApiGet.mockResolvedValueOnce({ posts })
+
+    await expect(fetchGekanatorPosts()).resolves.toEqual(posts)
+    expect(mockedApiGet).toHaveBeenCalledWith('/gekanator/posts')
+  })
+
+  it('returns questions from the Gekanator questions endpoint', async () => {
+    const questions: StoredGekanatorQuestion[] = []
+    mockedApiGet.mockResolvedValueOnce({ questions })
+
+    await expect(fetchGekanatorQuestions()).resolves.toEqual(questions)
+    expect(mockedApiGet).toHaveBeenCalledWith('/gekanator/questions')
+  })
+})
+
+describe('expectedAnswerForQuestion', () => {
+  it('returns a direct example answer when present', () => {
+    const question: StoredGekanatorQuestion = {
+      id: 'post-similarity:10',
+      text: '喜多ちゃんが泣いてる?',
+      kind: 'post_similarity',
+      source: 'user_suggested',
+      priorityWeight: 1.2,
+      condition: {
+        type: 'post-similarity',
+        postId: 999,
+        answer: 'yes',
+        threshold: 0.65,
+      },
+      exampleAnswers: {
+        1: 'partial',
+      },
+    }
+
+    expect(expectedAnswerForQuestion(question, post({ id: 1 }))).toBe('partial')
+  })
+
+  it('returns the condition answer for the original post_similarity post', () => {
+    const question: StoredGekanatorQuestion = {
+      id: 'post-similarity:10',
+      text: '喜多ちゃんが泣いてる?',
+      kind: 'post_similarity',
+      source: 'user_suggested',
+      priorityWeight: 1.2,
+      condition: {
+        type: 'post-similarity',
+        postId: 123,
+        answer: 'probably_no',
+        threshold: 0.65,
+      },
+    }
+
+    expect(expectedAnswerForQuestion(question, post({ id: 123 }))).toBe('probably_no')
+  })
+
+  it('returns null for an unrelated post_similarity post without examples', () => {
+    const question: StoredGekanatorQuestion = {
+      id: 'post-similarity:10',
+      text: '喜多ちゃんが泣いてる?',
+      kind: 'post_similarity',
+      source: 'user_suggested',
+      priorityWeight: 1.2,
+      condition: {
+        type: 'post-similarity',
+        postId: 123,
+        answer: 'yes',
+        threshold: 0.65,
+      },
+    }
+
+    expect(expectedAnswerForQuestion(question, post({ id: 456 }))).toBeNull()
+  })
+
+  it('returns yes for a matching tag question', () => {
+    const question: StoredGekanatorQuestion = {
+      id: 'tag:character:喜多郁代',
+      text: '喜多ちゃんが関係してる?',
+      kind: 'tag',
+      condition: {
+        type: 'tag',
+        key: 'character:喜多郁代',
+      },
+    }
+
+    expect(
+      expectedAnswerForQuestion(
+        question,
+        post({
+          tags: [
+            {
+              id: 1,
+              name: '喜多郁代',
+              category: 'character',
+              aliases: [],
+              parents: [],
+              postCount: 1,
+              createdAt: '2026-06-10T00:00:00.000Z',
+              updatedAt: '2026-06-10T00:00:00.000Z',
+              deprecatedAt: null,
+              hasWiki: false,
+              hasDeerjikists: false,
+              materialId: null,
+            },
+          ],
+        }),
+      ),
+    ).toBe('yes')
+  })
+
+  it('returns no for a non-matching tag question', () => {
+    const question: StoredGekanatorQuestion = {
+      id: 'tag:character:喜多郁代',
+      text: '喜多ちゃんが関係してる?',
+      kind: 'tag',
+      condition: {
+        type: 'tag',
+        key: 'character:喜多郁代',
+      },
+    }
+
+    expect(expectedAnswerForQuestion(question, post({ tags: [] }))).toBe('no')
+  })
+
+  it('ignores example answers for direct title facts', () => {
+    const question: StoredGekanatorQuestion = {
+      id: 'title:length-at-least:20',
+      text: 'タイトルは 20 文字以上?',
+      kind: 'title',
+      condition: {
+        type: 'title-length-at-least',
+        length: 20,
+      },
+      exampleAnswers: {
+        1: 'yes',
+      },
+    }
+
+    expect(expectedAnswerForQuestion(question, post({ id: 1, title: 'short' }))).toBe('no')
+  })
+
+  it('returns yes for matching title-contains questions', () => {
+    const question: StoredGekanatorQuestion = {
+      id: 'title:contains:結束バンド',
+      text: '題名に「結束バンド」が含まれる?',
+      kind: 'title',
+      condition: {
+        type: 'title-contains',
+        text: '結束バンド',
+      },
+    }
+
+    expect(expectedAnswerForQuestion(
+      question,
+      post({ title: '結束バンドのライブ' }),
+    )).toBe('yes')
+    expect(expectedAnswerForQuestion(
+      question,
+      post({ title: '後藤ひとりの休日' }),
+    )).toBe('no')
+  })
+})
+
+describe('learnedSemanticSideForPost', () => {
+  it('classifies post_similarity examples as positive, negative, or unknown', () => {
+    const question: StoredGekanatorQuestion = {
+      id: 'post-similarity:10',
+      text: '喜多ちゃんが泣いてる?',
+      kind: 'post_similarity',
+      source: 'user_suggested',
+      priorityWeight: 1.2,
+      condition: {
+        type: 'post-similarity',
+        postId: 123,
+        answer: 'partial',
+        threshold: 0.65,
+      },
+      exampleAnswers: {
+        1: 'yes',
+        2: 'probably_no',
+      },
+    }
+
+    expect(learnedSemanticSideForPost(question, post({ id: 1 }))).toBe('positive')
+    expect(learnedSemanticSideForPost(question, post({ id: 2 }))).toBe('negative')
+    expect(learnedSemanticSideForPost(question, post({ id: 3 }))).toBe('unknown')
+    expect(learnedSemanticSideForPost(question, post({ id: 123 }))).toBe('positive')
+  })
+})
+
+describe('restoreGekanatorQuestion', () => {
+  it('uses default source and priority weight when omitted', () => {
+    const question = restoreGekanatorQuestion({
+      id: 'tag:character:喜多郁代',
+      text: '喜多ちゃんが関係してる?',
+      kind: 'tag',
+      condition: {
+        type: 'tag',
+        key: 'character:喜多郁代',
+      },
+    })
+
+    expect(question.source).toBe('default')
+    expect(question.priorityWeight).toBe(1)
+  })
+
+  it('tests a post_similarity question using direct examples', () => {
+    const question = restoreGekanatorQuestion({
+      id: 'post-similarity:10',
+      text: '喜多ちゃんが泣いてる?',
+      kind: 'post_similarity',
+      source: 'user_suggested',
+      priorityWeight: 1.2,
+      condition: {
+        type: 'post-similarity',
+        postId: 999,
+        answer: 'yes',
+        threshold: 0.65,
+      },
+      exampleAnswers: {
+        1: 'yes',
+        2: 'no',
+      },
+    })
+
+    expect(question.test(post({ id: 1 }))).toBe(true)
+    expect(question.test(post({ id: 2 }))).toBe(false)
+    expect(question.test(post({ id: 3 }))).toBe(false)
+  })
+
+  it('tests a post_similarity question against its configured partial answer', () => {
+    const question = restoreGekanatorQuestion({
+      id: 'post-similarity:10',
+      text: '喜多ちゃんが泣いてる?',
+      kind: 'post_similarity',
+      source: 'user_suggested',
+      priorityWeight: 1.2,
+      condition: {
+        type: 'post-similarity',
+        postId: 999,
+        answer: 'partial',
+        threshold: 0.65,
+      },
+      exampleAnswers: {
+        1: 'partial',
+        2: 'yes',
+      },
+    })
+
+    expect(question.test(post({ id: 1 }))).toBe(true)
+    expect(question.test(post({ id: 2 }))).toBe(true)
+  })
+
+  it('normalizes legacy title-length-greater-than questions', () => {
+    const question = restoreGekanatorQuestion({
+      id: 'title:length-greater-than:20',
+      text: '題名が長めの投稿?',
+      kind: 'title',
+      condition: {
+        type: 'title-length-greater-than',
+        length: 20,
+      },
+    })
+
+    expect(question.id).toBe('title:length-at-least:21')
+    expect(question.condition).toEqual({
+      type: 'title-length-at-least',
+      length: 21,
+    })
+    expect(question.test(post({ title: 'x'.repeat(20) }))).toBe(false)
+    expect(question.test(post({ title: 'x'.repeat(21) }))).toBe(true)
+  })
+
+  it('restores title-contains questions with a title matcher', () => {
+    const question = restoreGekanatorQuestion({
+      id: 'title:contains:結束バンド',
+      text: '題名に「結束バンド」が含まれる?',
+      kind: 'title',
+      condition: {
+        type: 'title-contains',
+        text: '結束バンド',
+      },
+    })
+
+    expect(question.test(post({ title: '結束バンドのライブ' }))).toBe(true)
+    expect(question.test(post({ title: '後藤ひとりの休日' }))).toBe(false)
+  })
+})
+
+describe('buildGekanatorQuestions', () => {
+  it('builds quantitative title length questions', () => {
+    const questions = buildGekanatorQuestions([
+      post({ id: 1, title: 'a' }),
+      post({ id: 2, title: 'bb' }),
+      post({ id: 3, title: 'ccc' }),
+      post({ id: 4, title: 'dddd' }),
+    ])
+    const titleQuestion = questions.find(question =>
+      question.condition.type === 'title-length-at-least')
+
+    expect(titleQuestion?.text).toMatch(/^タイトルは \d+ 文字以上\?$/)
+    expect(titleQuestion?.id).toMatch(/^title:length-at-least:\d+$/)
+  })
+
+  it('builds title-contains questions from repeated title words', () => {
+    const questions = buildGekanatorQuestions([
+      post({ id: 1, title: '結束バンド ライブ' }),
+      post({ id: 2, title: '結束バンド 新曲' }),
+      post({ id: 3, title: '後藤ひとり 練習' }),
+      post({ id: 4, title: '伊地知虹夏 練習' }),
+    ])
+
+    const titleContainsQuestion = questions.find(question =>
+      question.condition.type === 'title-contains'
+      && question.condition.text === '結束バンド')
+
+    expect(titleContainsQuestion).toMatchObject({
+      id: 'title:contains:結束バンド',
+      text: '題名に「結束バンド」が含まれる?',
+      kind: 'title',
+      source: 'default',
+      priorityWeight: .96,
+    })
+    expect(titleContainsQuestion?.test(post({ title: '結束バンドのライブ' }))).toBe(true)
+    expect(titleContainsQuestion?.test(post({ title: '廣井きくりのライブ' }))).toBe(false)
+  })
+
+  it('honors question caps and title-contains toggles', () => {
+    const posts = [
+      post({ id: 1, title: '結束バンド ライブ' }),
+      post({ id: 2, title: '結束バンド 新曲' }),
+      post({ id: 3, title: '後藤ひとり 練習' }),
+      post({ id: 4, title: '伊地知虹夏 練習' }),
+    ]
+
+    const capped = buildGekanatorQuestions(posts, {
+      titleContainsCap: 1,
+      totalQuestionCap: 1,
+    })
+    const withoutTitleContains = buildGekanatorQuestions(posts, {
+      includeTitleContains: false,
+    })
+
+    expect(capped).toHaveLength(1)
+    expect(withoutTitleContains.some(question =>
+      question.condition.type === 'title-contains')).toBe(false)
+  })
+})
+
+describe('questionIdForCondition', () => {
+  it('builds stable ids for title-contains questions', () => {
+    expect(questionIdForCondition({
+      type: 'title-contains',
+      text: '結束バンド',
+    })).toBe('title:contains:結束バンド')
+  })
+})
+
+describe('Gekanator API writers', () => {
+  beforeEach(() => {
+    mockedApiPost.mockReset()
+  })
+
+  it('sends game results using snake_case request keys', async () => {
+    mockedApiPost.mockResolvedValue({ id: 100 })
+
+    const answers: GekanatorAnswerLog[] = [
+      {
+        questionId: 'tag:character:喜多郁代',
+        questionText: '喜多ちゃんが関係してる?',
+        questionCondition: {
+          type: 'tag',
+          key: 'character:喜多郁代',
+        },
+        questionMode: 'normal',
+        questionPurpose: 'effective_user_suggested',
+        effectiveQuestion: true,
+        learningQuestion: false,
+        answer: 'yes',
+        originalAnswer: 'partial',
+      },
+    ]
+
+    await expect(
+      saveGekanatorGame({
+        guessedPostId: 1,
+        correctPostId: 2,
+        answers,
+      }),
+    ).resolves.toEqual({ id: 100 })
+
+    expect(mockedApiPost).toHaveBeenCalledWith('/gekanator/games', {
+      guessed_post_id: 1,
+      correct_post_id: 2,
+      answers: [
+        {
+          question_id: 'tag:character:喜多郁代',
+          question_text: '喜多ちゃんが関係してる?',
+          question_condition: {
+            type: 'tag',
+            key: 'character:喜多郁代',
+          },
+          question_mode: 'normal',
+          question_purpose: 'effective_user_suggested',
+          effective_question: true,
+          learning_question: false,
+          answer: 'yes',
+          original_answer: 'partial',
+        },
+      ],
+    })
+  })
+
+  it('sends question suggestions using snake_case request keys', async () => {
+    mockedApiPost.mockResolvedValue({
+      id: 10,
+      count: 1,
+    })
+
+    await expect(
+      saveGekanatorQuestionSuggestion({
+        gekanatorGameId: 100,
+        questionText: '喜多ちゃんが泣いてる?',
+        answer: 'yes',
+      }),
+    ).resolves.toEqual({
+      id: 10,
+      count: 1,
+    })
+
+    expect(mockedApiPost).toHaveBeenCalledWith('/gekanator/question_suggestions', {
+      gekanator_game_id: 100,
+      question_text: '喜多ちゃんが泣いてる?',
+      answer: 'yes',
+    })
+  })
+
+  it('sends extra question answers using snake_case request keys', async () => {
+    mockedApiPost.mockResolvedValue({
+      count: 2,
+    })
+
+    await saveGekanatorExtraQuestionAnswers({
+      gameId: 100,
+      answers: [
+        {
+          questionId: 10,
+          answer: 'yes',
+        },
+        {
+          questionId: 11,
+          answer: 'probably_no',
+        },
+      ],
+    })
+
+    expect(mockedApiPost).toHaveBeenCalledWith(
+      '/gekanator/games/100/extra_question_answers',
+      {
+        answers: [
+          {
+            question_id: 10,
+            answer: 'yes',
+          },
+          {
+            question_id: 11,
+            answer: 'probably_no',
+          },
+        ],
+      },
+    )
+  })
+})

frontend/src/lib/gekanator.ts

@@ -1,5 +1,4 @@
-import { apiPost } from '@/lib/api'
-import { fetchPosts } from '@/lib/posts'
+import { apiGet, apiPost } from '@/lib/api'
 
 import type { Post } from '@/types'
 
@@ -10,22 +9,192 @@ export type GekanatorAnswerValue =
     | 'probably_no'
     | 'unknown'
 
+export type LearnedSemanticSide =
+    | 'positive'
+    | 'negative'
+    | 'unknown'
+
+export type GekanatorQuestionPurpose =
+    | 'effective_user_suggested'
+    | 'learning_user_suggested'
+    | 'normal'
+
 export type GekanatorAnswerLog = {
-    questionId:    string
-    questionText:  string
-    answer:        GekanatorAnswerValue }
+    questionId:       string
+    questionText:     string
+    questionCondition?:  GekanatorQuestionCondition
+    questionMode?:    'normal' | 'winning_run'
+    questionPurpose?: GekanatorQuestionPurpose
+    effectiveQuestion?: boolean
+    learningQuestion?: boolean
+    answer:           GekanatorAnswerValue
+    originalAnswer:   GekanatorAnswerValue }
 
 export type GekanatorQuestionKind =
     | 'tag'
     | 'source'
     | 'title'
     | 'original_date'
+    | 'post_similarity'
+
+export type GekanatorQuestionSource =
+    | 'default'
+    | 'user_suggested'
+    | 'ai_generated'
+    | 'admin_curated'
+
+export type GekanatorPerformanceMode = 'normal'
+
+export type GekanatorQuestionCondition =
+    | { type: 'tag'; key: string }
+    | { type: 'source'; host: string }
+    | { type: 'original-year'; year: number }
+    | { type: 'original-month'; month: number }
+    | { type: 'original-month-day'; monthDay: string }
+    | { type: 'title-length-at-least'; length: number }
+    | { type: 'title-length-greater-than'; length: number }
+    | { type: 'title-has-ascii' }
+    | { type: 'title-contains'; text: string }
+    | {
+	  type: 'post-similarity'
+	  postId: number
+	  answer: GekanatorAnswerValue
+	  threshold: number
+      }
+
+
+type NonPostSimilarityCondition = Exclude<
+    GekanatorQuestionCondition,
+    { type: 'post-similarity' }
+>
+
+export type GekanatorExtraQuestion = {
+    id:              number
+    text:            string
+    source:          GekanatorQuestionSource
+    priorityWeight:  number }
+
+export type StoredGekanatorQuestion = {
+    recordId?:       number
+    id:              string
+    text:            string
+    kind:            GekanatorQuestionKind
+    condition:       GekanatorQuestionCondition
+    source?:         GekanatorQuestionSource
+    priorityWeight?: number
+    exampleAnswers?: Record<`${ number }`, GekanatorAnswerValue> }
 
 export type GekanatorQuestion = {
-    id:    string
-    text:  string
-    kind:  GekanatorQuestionKind
-    test:  (post: Post) => boolean }
+    recordId?:       number
+    id:              string
+    text:            string
+    kind:            GekanatorQuestionKind
+    condition:       GekanatorQuestionCondition
+    source:          GekanatorQuestionSource
+    priorityWeight:  number
+    exampleAnswers?: Record<`${ number }`, GekanatorAnswerValue>
+    test:            (post: Post) => boolean }
+
+export type BuildGekanatorQuestionsOptions = {
+    includeTitleContains?: boolean
+    tagQuestionCap?: number
+    titleContainsCap?: number
+    totalQuestionCap?: number
+}
+
+
+export const normalizeTitleLengthCondition = (
+    condition:  GekanatorQuestionCondition,
+): GekanatorQuestionCondition => {
+  switch (condition.type)
+  {
+  case 'title-length-greater-than':
+    return {
+	type:   'title-length-at-least',
+	length: condition.length + 1 }
+  default:
+    return condition
+  }
+}
+
+
+export const titleLengthMinimumForCondition = (
+    condition:  GekanatorQuestionCondition,
+): number | null => {
+  switch (condition.type)
+  {
+  case 'title-length-at-least':
+    return condition.length
+  case 'title-length-greater-than':
+    return condition.length + 1
+  default:
+    return null
+  }
+}
+
+
+export const questionIdForCondition = (
+    condition:  NonPostSimilarityCondition,
+): string => {
+  switch (condition.type)
+  {
+  case 'tag':
+    return `tag:${ condition.key }`
+  case 'source':
+    return `source:${ condition.host }`
+  case 'original-year':
+    return `original-year:${ condition.year }`
+  case 'original-month':
+    return `original-month:${ condition.month }`
+  case 'original-month-day':
+    return `original-month-day:${ condition.monthDay }`
+  case 'title-length-at-least':
+  case 'title-length-greater-than':
+    return `title:length-at-least:${ titleLengthMinimumForCondition (condition) }`
+  case 'title-has-ascii':
+    return 'title:ascii'
+  case 'title-contains':
+    return `title:contains:${ condition.text }`
+  }
+}
+
+
+const directExampleAnswerFor = (
+    question:  StoredGekanatorQuestion,
+    post:      Post,
+): GekanatorAnswerValue | null => {
+  if (question.kind !== 'post_similarity' && question.kind !== 'tag')
+    return null
+
+  const direct = question.exampleAnswers?.[String (post.id) as `${ number }`]
+  if (direct)
+    return direct
+
+  if (question.condition.type === 'post-similarity' && question.condition.postId === post.id)
+    return question.condition.answer
+
+  return null
+}
+
+
+export const isLearnedSemanticQuestion = (
+    question:  StoredGekanatorQuestion | GekanatorQuestion,
+): boolean =>
+    question.kind === 'post_similarity'
+    && question.source === 'user_suggested'
+
+
+export const learnedSemanticSideForAnswer = (
+    answer:  GekanatorAnswerValue | null,
+): LearnedSemanticSide => {
+  if (answer === 'yes' || answer === 'partial')
+    return 'positive'
+
+  if (answer === 'no' || answer === 'probably_no')
+    return 'negative'
+
+  return 'unknown'
+}
 
 const countBy = <T extends string | number> (values: T[]): Map<T, number> => {
   const counts = new Map<T, number> ()
@@ -65,6 +234,37 @@ const originalYearOf = (post: Post): number | null => {
 }
 
 
+const originalDateOf = (post: Post): Date | null => {
+  const value = post.originalCreatedFrom || post.originalCreatedBefore
+  if (!(value))
+    return null
+
+  const date = new Date (value)
+  if (Number.isNaN (date.getTime ()))
+    return null
+
+  return date
+}
+
+
+const originalMonthOf = (post: Post): number | null => {
+  const date = originalDateOf (post)
+  if (!(date))
+    return null
+
+  return date.getMonth () + 1
+}
+
+
+const originalMonthDayOf = (post: Post): string | null => {
+  const date = originalDateOf (post)
+  if (!(date))
+    return null
+
+  return `${ date.getMonth () + 1 }-${ date.getDate () }`
+}
+
+
 const tagQuestionKey = ({ category, name }: { category: string; name: string }): string =>
     `${ category }:${ name }`
 
@@ -78,6 +278,27 @@ const tagFromQuestionKey = (key: string): { category: string; name: string } =>
 const nicoTagLabel = (name: string): string => name.replace (/^nico:/, '')
 
 
+const tagQuestionText = (category: string, label: string): string => {
+  switch (category)
+  {
+  case 'deerjikist':
+    return `作者・ニジラーとして「${ label }」に関係してゐる?`
+  case 'meme':
+    return `元ネタ・ミームとして「${ label }」に関係しさう?`
+  case 'character':
+    return `「${ label }」といふキャラクターが関係してゐる?`
+  case 'material':
+    return `素材として「${ label }」に関係してゐる?`
+  case 'nico':
+    return `ニコニコに「${ label }」といふタグが付いてゐる?`
+  case 'general':
+  case 'meta':
+  default:
+    return `内容として「${ label }」に関係しさう?`
+  }
+}
+
+
 const questionableTag = (post: Post, key: string): boolean => {
   const { category, name } = tagFromQuestionKey (key)
 
@@ -91,31 +312,149 @@ const questionableTag = (post: Post, key: string): boolean => {
 }
 
 
-export const fetchGekanatorPosts = async (): Promise<Post[]> => {
-  const limit = 200
-  const first = await fetchPosts ({
-      url: '', title: '', tags: '', match: 'all',
-      originalCreatedFrom: '', originalCreatedTo: '',
-      createdFrom: '', createdTo: '', updatedFrom: '', updatedTo: '',
-      page: 1, limit, order: 'original_created_at:desc' })
-  const posts = [...first.posts]
-  const totalPages = Math.ceil (first.count / limit)
+const questionMatches = (
+    post:       Post,
+    question:   StoredGekanatorQuestion,
+): boolean => {
+  const directAnswer = directExampleAnswerFor (question, post)
+  if (directAnswer)
+    return question.kind === 'post_similarity'
+	? learnedSemanticSideForAnswer (directAnswer) === 'positive'
+	: directAnswer === 'yes'
 
-  for (let page = 2; page <= totalPages; page++)
-    {
-      const data = await fetchPosts ({
-	  url: '', title: '', tags: '', match: 'all',
-	  originalCreatedFrom: '', originalCreatedTo: '',
-	  createdFrom: '', createdTo: '', updatedFrom: '', updatedTo: '',
-	  page, limit, order: 'original_created_at:desc' })
-      posts.push (...data.posts)
-    }
-
-  return posts
+  switch (question.condition.type)
+  {
+  case 'tag':
+    return questionableTag (post, question.condition.key)
+  case 'source':
+    return hostOf (post) === question.condition.host
+  case 'original-year':
+    return originalYearOf (post) === question.condition.year
+  case 'original-month':
+    return originalMonthOf (post) === question.condition.month
+  case 'original-month-day':
+    return originalMonthDayOf (post) === question.condition.monthDay
+  case 'title-length-at-least':
+    return (post.title?.length ?? 0) >= question.condition.length
+  case 'title-length-greater-than':
+    return (post.title?.length ?? 0) > question.condition.length
+  case 'title-has-ascii':
+    return /[A-Za-z0-9]/.test (post.title ?? '')
+  case 'title-contains':
+    return (post.title ?? '').includes (question.condition.text)
+  case 'post-similarity':
+    return false
+  }
 }
 
 
-export const buildGekanatorQuestions = (posts: Post[]): GekanatorQuestion[] => {
+export const expectedAnswerForQuestion = (
+    question:  StoredGekanatorQuestion | GekanatorQuestion | undefined,
+    post:      Post | null,
+): GekanatorAnswerValue | null => {
+  if (!(question) || !(post))
+    return null
+
+  const directAnswer = directExampleAnswerFor (question, post)
+  if (directAnswer)
+    return directAnswer
+
+  switch (question.condition.type)
+  {
+  case 'post-similarity':
+    if (question.condition.postId === post.id)
+      return question.condition.answer
+
+    return null
+  case 'tag':
+  case 'source':
+  case 'original-year':
+  case 'original-month':
+  case 'original-month-day':
+  case 'title-length-at-least':
+  case 'title-length-greater-than':
+  case 'title-has-ascii':
+  case 'title-contains':
+    return questionMatches (post, question) ? 'yes' : 'no'
+  }
+}
+
+
+export const learnedSemanticSideForPost = (
+    question:  StoredGekanatorQuestion | GekanatorQuestion | undefined,
+    post:      Post | null,
+): LearnedSemanticSide =>
+    learnedSemanticSideForAnswer (expectedAnswerForQuestion (question, post))
+
+
+export const restoreGekanatorQuestion = (
+    question:  StoredGekanatorQuestion,
+): GekanatorQuestion => {
+  const normalizedCondition = normalizeTitleLengthCondition (question.condition)
+  const normalizedQuestion = {
+      ...question,
+      recordId: question.recordId,
+      id: normalizedCondition.type === 'title-length-at-least'
+	  ? `title:length-at-least:${ normalizedCondition.length }`
+	  : question.id,
+      condition: normalizedCondition,
+      source: question.source ?? 'default',
+      priorityWeight: question.priorityWeight ?? 1 }
+
+  return {
+      ...normalizedQuestion,
+      test: (post: Post) => questionMatches (post, normalizedQuestion) }
+}
+
+
+export const storeGekanatorQuestion = (
+    question:  GekanatorQuestion,
+): StoredGekanatorQuestion => ({
+  id: question.condition.type === 'title-length-greater-than'
+      ? `title:length-at-least:${ question.condition.length + 1 }`
+      : question.id,
+  recordId: question.recordId,
+  text: question.text,
+  kind: question.kind,
+  condition: normalizeTitleLengthCondition (question.condition),
+  source: question.source,
+  priorityWeight: question.priorityWeight,
+  exampleAnswers: question.exampleAnswers })
+
+
+export const fetchGekanatorPosts = async (): Promise<Post[]> => {
+  const data = await apiGet<{ posts: Post[] }> ('/gekanator/posts')
+  return data.posts
+}
+
+
+export const fetchGekanatorQuestions = async (): Promise<StoredGekanatorQuestion[]> => {
+  const data = await apiGet<{ questions: StoredGekanatorQuestion[] }> ('/gekanator/questions')
+  return data.questions
+}
+
+
+export const fetchGekanatorExtraQuestions = async (
+    gameId:  number,
+    nonce?: string,
+): Promise<GekanatorExtraQuestion[]> => {
+  const data = await apiGet<{ questions: GekanatorExtraQuestion[] }> (
+      `/gekanator/games/${ gameId }/extra_questions`,
+      { params: nonce ? { nonce } : undefined })
+  return data.questions
+}
+
+
+export const buildGekanatorQuestions = (
+    posts:    Post[],
+    options:  BuildGekanatorQuestionsOptions = { },
+): GekanatorQuestion[] => {
+  const {
+      includeTitleContains = true,
+      tagQuestionCap = 192,
+      titleContainsCap = 24,
+      totalQuestionCap = Number.POSITIVE_INFINITY,
+  } = options
   const tagCounts = countBy (posts.flatMap (post =>
       post.tags
       .filter (tag =>
@@ -127,72 +466,157 @@ export const buildGekanatorQuestions = (posts: Post[]): GekanatorQuestion[] => {
   const originalYears = countBy (
       posts
       .map (originalYearOf)
-      .filter ((year): year is number => year !== null))
+      .filter ((year): year is number => year != null))
+  const originalMonths = countBy (
+      posts
+      .map (originalMonthOf)
+      .filter ((month): month is number => month != null))
+  const originalMonthDays = countBy (
+      posts
+      .map (originalMonthDayOf)
+      .filter ((monthDay): monthDay is string => monthDay != null))
   const titleLengthMedian = median (posts.map (post => post.title?.length ?? 0))
+  const titleWordCounts =
+      includeTitleContains
+	? countBy (
+	    posts.flatMap (post =>
+		Array.from (
+		    new Set (
+			(post.title ?? '')
+			.match (
+			    /[\p{Script=Han}\p{Script=Hiragana}\p{Script=Katakana}A-Za-z0-9]{2,}/gu)
+			?? []))))
+	: new Map<string, number> ()
 
-  const usefulEntries = <T extends string | number> (counts: Map<T, number>) =>
+  const usefulEntries = <T extends string | number> (
+      counts:  Map<T, number>,
+      cap:     number,
+  ) =>
       [...counts.entries ()]
       .filter (([, count]) => count > 0 && count < posts.length)
       .sort ((a, b) => Math.abs (posts.length / 2 - a[1])
 	       - Math.abs (posts.length / 2 - b[1]))
-      .slice (0, 80)
+      .slice (0, cap)
 
-  const tagQuestions = usefulEntries (tagCounts)
+  const tagQuestions = usefulEntries (tagCounts, Math.max (tagQuestionCap, 80))
       .filter (([, count]) => count >= 2 && count <= Math.max (2, posts.length * .7))
-      .slice (0, 80)
+      .slice (0, tagQuestionCap)
       .map (([key]) => {
 	const { category, name } = tagFromQuestionKey (String (key))
 	const label = category === 'nico' ? nicoTagLabel (name) : name
 
 	return {
 	    id:   `tag:${ key }`,
-	    text: category === 'nico'
-		? `ニコニコに「${ label }」といふタグが付いてゐる?`
-		: `内容として「${ label }」に関係しさう?`,
+	    text: tagQuestionText (category, label),
 	    kind: 'tag' as const,
+	    condition: { type: 'tag' as const, key: String (key) },
+	    source: 'default' as const,
+	    priorityWeight: 1,
 	    test: (post: Post) => questionableTag (post, String (key)) }
       })
 
-  const sourceQuestions = usefulEntries (hosts)
+  const sourceQuestions = usefulEntries (hosts, 20)
       .filter (([, count]) => count >= 2 && count <= Math.max (2, posts.length * .7))
       .slice (0, 20)
       .map (([host]) => ({
 	  id:   `source:${ host }`,
 	  text: `${ host } の投稿を思ひ浮かべてゐる?`,
 	  kind: 'source' as const,
+	  condition: { type: 'source' as const, host },
+	  source: 'default' as const,
+	  priorityWeight: 1,
 	  test: (post: Post) => hostOf (post) === host }))
 
-  const originalYearQuestions = usefulEntries (originalYears)
+  const originalYearQuestions = usefulEntries (originalYears, 20)
       .filter (([, count]) => count >= 2 && count <= Math.max (2, posts.length * .7))
       .slice (0, 20)
       .map (([year]) => ({
 	  id:   `original-year:${ year }`,
 	  text: `オリジナルの投稿年は ${ year } 年?`,
 	  kind: 'original_date' as const,
+	  condition: { type: 'original-year' as const, year },
+	  source: 'default' as const,
+	  priorityWeight: 1,
 	  test: (post: Post) => originalYearOf (post) === year }))
 
+  const originalMonthQuestions = usefulEntries (originalMonths, 20)
+      .filter (([, count]) => count >= 2 && count <= Math.max (2, posts.length * .7))
+      .slice (0, 20)
+      .map (([month]) => ({
+	  id:   `original-month:${ month }`,
+	  text: `オリジナルの投稿月は ${ month } 月?`,
+	  kind: 'original_date' as const,
+	  condition: { type: 'original-month' as const, month },
+	  source: 'default' as const,
+	  priorityWeight: 1,
+	  test: (post: Post) => originalMonthOf (post) === month }))
+
+  const originalMonthDayQuestions = usefulEntries (originalMonthDays, 20)
+      .filter (([, count]) => count >= 2 && count <= Math.max (2, posts.length * .7))
+      .slice (0, 20)
+      .map (([monthDay]) => {
+	const [month, day] = String (monthDay).split ('-')
+
+	return {
+	    id:   `original-month-day:${ monthDay }`,
+	    text: `オリジナルの投稿日は ${ month } 月 ${ day } 日?`,
+	    kind: 'original_date' as const,
+	    condition: { type: 'original-month-day' as const, monthDay: String (monthDay) },
+	    source: 'default' as const,
+	    priorityWeight: 1,
+	    test: (post: Post) => originalMonthDayOf (post) === monthDay }
+      })
+
   const titleQuestions = [
       {
-	  id:   'title:long',
-	  text: '題名が長めの投稿?',
+	  id:   `title:length-at-least:${ titleLengthMedian }`,
+	  text: `タイトルは ${ titleLengthMedian } 文字以上?`,
 	  kind: 'title' as const,
-	  test: (post: Post) => (post.title?.length ?? 0) > titleLengthMedian },
+	  condition: {
+	      type: 'title-length-at-least' as const,
+	      length: titleLengthMedian },
+	  source: 'default' as const,
+	  priorityWeight: 1,
+	  test: (post: Post) => (post.title?.length ?? 0) >= titleLengthMedian },
       {
 	  id:   'title:ascii',
 	  text: '題名に英数字が混じってゐる?',
 	  kind: 'title' as const,
+	  condition: { type: 'title-has-ascii' as const },
+	  source: 'default' as const,
+	  priorityWeight: 1,
 	  test: (post: Post) => /[A-Za-z0-9]/.test (post.title ?? '') }]
       .filter (question => {
 	const yes = posts.filter (post => question.test (post)).length
 	const no = posts.length - yes
 	return yes >= 2 && no >= 2 && yes <= posts.length * .7 && no <= posts.length * .7
       })
+  const titleContainsQuestions =
+      includeTitleContains
+	? usefulEntries (titleWordCounts, titleContainsCap)
+	    .filter (([word, count]) =>
+		String (word).length <= 24
+		&& count >= 2
+		&& count <= Math.max (2, posts.length * .7))
+	    .slice (0, titleContainsCap)
+	    .map (([word]) => ({
+		id:   `title:contains:${ word }`,
+		text: `題名に「${ word }」が含まれる?`,
+		kind: 'title' as const,
+		condition: { type: 'title-contains' as const, text: String (word) },
+		source: 'default' as const,
+		priorityWeight: .96,
+		test: (post: Post) => (post.title ?? '').includes (String (word)) }))
+	: []
 
   return [
       ...sourceQuestions,
       ...originalYearQuestions,
+      ...originalMonthQuestions,
+      ...originalMonthDayQuestions,
       ...titleQuestions,
-      ...tagQuestions]
+      ...titleContainsQuestions,
+      ...tagQuestions].slice (0, totalQuestionCap)
 }
 
 
@@ -204,11 +628,48 @@ export const saveGekanatorGame = async ({
     guessedPostId:  number
     correctPostId:  number
     answers:        GekanatorAnswerLog[]
-}): Promise<{ id: number }> =>
+}): Promise<{ id: number; learnedExampleCount: number }> =>
     await apiPost ('/gekanator/games', {
 	guessed_post_id: guessedPostId,
 	correct_post_id: correctPostId,
 	answers: answers.map (answer => ({
 	    question_id: answer.questionId,
 	    question_text: answer.questionText,
-	    answer: answer.answer })) })
+	    question_condition: answer.questionCondition ?? null,
+	    question_mode: answer.questionMode,
+	    question_purpose: answer.questionPurpose,
+	    effective_question: answer.effectiveQuestion,
+	    learning_question: answer.learningQuestion,
+	    answer: answer.answer,
+	    original_answer: answer.originalAnswer })) })
+
+
+export const saveGekanatorQuestionSuggestion = async ({
+    gekanatorGameId,
+    existingQuestionId,
+    questionText,
+    answer,
+}: {
+    gekanatorGameId:  number
+    existingQuestionId?: number
+    questionText?:    string
+    answer:           GekanatorAnswerValue
+}): Promise<{ id: number; count: number }> =>
+    await apiPost ('/gekanator/question_suggestions', {
+	gekanator_game_id: gekanatorGameId,
+	existing_question_id: existingQuestionId,
+	question_text: questionText,
+	answer })
+
+
+export const saveGekanatorExtraQuestionAnswers = async ({
+    gameId,
+    answers,
+}: {
+    gameId:   number
+    answers:  { questionId: number; answer: GekanatorAnswerValue }[]
+}) =>
+    await apiPost (`/gekanator/games/${ gameId }/extra_question_answers`, {
+	answers: answers.map (item => ({
+	    question_id: item.questionId,
+	    answer: item.answer })) })

frontend/src/lib/gekanatorCandidateRecovery.test.ts

@@ -0,0 +1,259 @@
+import { describe, expect, it } from 'vitest'
+
+import {
+    candidatePostsFor,
+    hardFilteredPostsForAnswer,
+    recoverCandidatePosts,
+} from '@/lib/gekanatorCandidateRecovery'
+
+import type {
+    GekanatorAnswerLog,
+    GekanatorAnswerValue,
+    GekanatorQuestion,
+} from '@/lib/gekanator'
+import type { RecoveredCandidateState } from '@/lib/gekanatorCandidateRecovery'
+import type { Post } from '@/types'
+
+
+const post = (id: number): Post => ({
+  id,
+  versionNo: 1,
+  url: `https://example.com/posts/${ id }`,
+  title: `post ${ id }`,
+  thumbnail: null,
+  thumbnailBase: null,
+  tags: [],
+  viewed: false,
+  related: [],
+  originalCreatedFrom: null,
+  originalCreatedBefore: null,
+  createdAt: '2026-06-10T00:00:00.000Z',
+  updatedAt: '2026-06-10T00:00:00.000Z',
+  uploadedUser: null,
+})
+
+
+const postSimilarityQuestion = (
+    id:       string,
+    answers:  Record<`${ number }`, GekanatorAnswerValue>,
+): GekanatorQuestion => ({
+  id,
+  text: `${ id }?`,
+  kind: 'post_similarity',
+  condition: {
+      type: 'post-similarity',
+      postId: 9999,
+      answer: 'yes',
+      threshold: 0.65 },
+  source: 'user_suggested',
+  priorityWeight: 1,
+  exampleAnswers: answers,
+  test: candidate => answers[String (candidate.id) as `${ number }`] === 'yes',
+})
+
+
+const sourceQuestion = (
+    host:  string,
+): GekanatorQuestion => ({
+  id: `source:${ host }`,
+  text: `${ host }?`,
+  kind: 'source',
+  condition: {
+      type: 'source',
+      host },
+  source: 'default',
+  priorityWeight: 1,
+  test: candidate => new URL (candidate.url).hostname === host,
+})
+
+
+const answer = (
+    question:  GekanatorQuestion,
+    value:     GekanatorAnswerValue,
+): GekanatorAnswerLog => ({
+  questionId: question.id,
+  questionText: question.text,
+  questionCondition: question.condition,
+  answer: value,
+  originalAnswer: value,
+})
+
+
+const recoveredState = (
+    answerCountAtRecovery:  number,
+    scoreAtRecovery = 0,
+): RecoveredCandidateState => ({
+  answerCountAtRecovery,
+  scoreAtRecovery,
+})
+
+
+describe('candidatePostsFor', () => {
+  it('does not hard-filter semantic post_similarity answers', () => {
+    const posts = [post (1), post (2), post (3)]
+    const oldQuestion = postSimilarityQuestion ('old', {
+	1: 'no',
+	2: 'yes',
+	3: 'yes',
+    })
+    const laterQuestion = postSimilarityQuestion ('later', {
+	1: 'no',
+	2: 'no',
+	3: 'yes',
+    })
+
+    const candidates = candidatePostsFor ({
+	posts,
+	questions: [oldQuestion, laterQuestion],
+	answers: [answer (oldQuestion, 'yes'), answer (laterQuestion, 'yes')],
+	softenedQuestionIds: new Set (),
+	rejectedPostIds: new Set (),
+	recoveredCandidatePosts: new Map ([
+	    [1, recoveredState (1)],
+	    [3, recoveredState (1)],
+	]) })
+
+    expect(candidates.map (candidate => candidate.id)).toEqual ([1, 2, 3])
+  })
+
+  it('lets recovered candidates ignore old fact answers but not later fact answers', () => {
+    const posts = [
+	{ ...post (1), url: 'https://other.example/posts/1' },
+	post (2),
+	{ ...post (3), url: 'https://example.com/posts/3' },
+    ]
+    const oldQuestion = sourceQuestion ('old.example.com')
+    const laterQuestion = sourceQuestion ('example.com')
+
+    const candidates = candidatePostsFor ({
+	posts,
+	questions: [oldQuestion, laterQuestion],
+	answers: [answer (oldQuestion, 'yes'), answer (laterQuestion, 'yes')],
+	softenedQuestionIds: new Set (),
+	rejectedPostIds: new Set (),
+	recoveredCandidatePosts: new Map ([
+	    [1, recoveredState (1)],
+	    [3, recoveredState (1)],
+	]) })
+
+    expect(candidates.map (candidate => candidate.id)).toEqual ([3])
+  })
+
+  it('does not let recovered candidates bypass explicit rejected posts', () => {
+    const posts = [post (1), post (2)]
+    const question = postSimilarityQuestion ('question', {
+	1: 'yes',
+	2: 'yes',
+    })
+
+    const candidates = candidatePostsFor ({
+	posts,
+	questions: [question],
+	answers: [answer (question, 'yes')],
+	softenedQuestionIds: new Set (),
+	rejectedPostIds: new Set ([1]),
+	recoveredCandidatePosts: new Map ([[1, recoveredState (1)]]) })
+
+    expect(candidates.map (candidate => candidate.id)).toEqual ([2])
+  })
+})
+
+
+describe('hardFilteredPostsForAnswer', () => {
+  it('keeps the original pool for semantic post_similarity answers', () => {
+    const posts = [post (1), post (2)]
+    const question = postSimilarityQuestion ('question', {
+	1: 'yes',
+	2: 'yes',
+    })
+
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'no',
+    })).toEqual (posts)
+  })
+
+  it('hard-filters fact answers only for yes and no', () => {
+    const posts = [
+	{ ...post (1), url: 'https://example.com/posts/1' },
+	{ ...post (2), url: 'https://other.example/posts/2' },
+    ]
+    const question = sourceQuestion ('example.com')
+
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'yes',
+    }).map (candidate => candidate.id)).toEqual ([1])
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'no',
+    }).map (candidate => candidate.id)).toEqual ([2])
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'partial',
+    })).toEqual (posts)
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'probably_no',
+    })).toEqual (posts)
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'unknown',
+    })).toEqual (posts)
+  })
+})
+
+
+describe('recoverCandidatePosts', () => {
+  it('recovers high-score non-rejected, non-eligible candidates in staged batches', () => {
+    const posts = Array.from ({ length: 10 }, (_value, index) => post (index + 1))
+    const scores = new Map (posts.map (candidate => [candidate.id, candidate.id]))
+
+    const recovered = recoverCandidatePosts ({
+	posts,
+	scores,
+	rejectedPostIds: new Set ([10]),
+	recoveredCandidatePosts: new Map ([[8, recoveredState (1, 8)]]),
+	eligiblePostIds: new Set ([9]),
+	answerCountAtRecovery: 2,
+	recoveryStepCount: 0,
+    })
+
+    expect(recovered?.recoveryStepCount).toBe (1)
+    expect([...(recovered?.recoveredCandidatePosts.keys () ?? [])])
+      .toEqual ([8, 7, 6, 5, 4])
+    expect(recovered?.recoveredCandidatePosts.get (7)).toEqual ({
+	answerCountAtRecovery: 2,
+	scoreAtRecovery: 7,
+    })
+  })
+
+  it('does not add posts when recovered and eligible candidates already hit the target', () => {
+    const posts = Array.from ({ length: 10 }, (_value, index) => post (index + 1))
+    const scores = new Map (posts.map (candidate => [candidate.id, candidate.id]))
+
+    const recovered = recoverCandidatePosts ({
+	posts,
+	scores,
+	rejectedPostIds: new Set (),
+	recoveredCandidatePosts: new Map ([
+	    [1, recoveredState (1, 1)],
+	    [2, recoveredState (1, 2)],
+	    [3, recoveredState (1, 3)],
+	]),
+	eligiblePostIds: new Set ([4, 5, 6]),
+	answerCountAtRecovery: 2,
+	recoveryStepCount: 0,
+    })
+
+    expect(recovered?.recoveryStepCount).toBe (1)
+    expect([...(recovered?.recoveredCandidatePosts.keys () ?? [])])
+      .toEqual ([1, 2, 3])
+  })
+})

frontend/src/lib/gekanatorCandidateRecovery.ts

@@ -0,0 +1,159 @@
+import { isLearnedSemanticQuestion,
+	 learnedSemanticSideForPost } from '@/lib/gekanator'
+
+import type { GekanatorAnswerLog, GekanatorAnswerValue, GekanatorQuestion } from '@/lib/gekanator'
+import type { Post } from '@/types'
+
+export type RecoveredCandidatePost = {
+    postId:                number
+    answerCountAtRecovery: number
+    scoreAtRecovery:       number }
+
+export type RecoveredCandidateState = {
+    answerCountAtRecovery: number
+    scoreAtRecovery:       number }
+
+
+const questionSupportsAnswerBasedHardFiltering = (question:  GekanatorQuestion): boolean =>
+    !(isLearnedSemanticQuestion (question)
+      || (question.kind === 'tag'
+	  && question.condition.type === 'tag'
+	  && !(question.condition.key.startsWith ('nico:'))))
+
+
+export const candidatePostsFor = (
+    { posts,
+      questions,
+      answers,
+      softenedQuestionIds,
+      rejectedPostIds,
+      recoveredCandidatePosts }: { posts:                   Post[]
+				   questions:               GekanatorQuestion[]
+				   answers:                 GekanatorAnswerLog[]
+				   softenedQuestionIds:     Set<string>
+				   rejectedPostIds:         Set<number>
+				   recoveredCandidatePosts: Map<number, RecoveredCandidateState> },
+): Post[] => {
+  const questionById = new Map (questions.map (question => [question.id, question]))
+
+  return posts.filter (post => {
+    if (rejectedPostIds.has (post.id))
+      return false
+
+    const recoveredCandidate = recoveredCandidatePosts.get (post.id)
+
+    return answers.every ((answer, index) => {
+      if (recoveredCandidate != null && index < recoveredCandidate.answerCountAtRecovery)
+	return true
+
+      if (softenedQuestionIds.has (answer.questionId))
+	return true
+
+      const question = questionById.get (answer.questionId)
+      if (!(question))
+	return true
+      if (!(questionSupportsAnswerBasedHardFiltering (question)))
+	return true
+
+      switch (answer.answer)
+      {
+      case 'yes':
+      case 'no':
+	{
+	  const expected = learnedSemanticSideForPost (question, post)
+	  return expected === 'unknown'
+	      || (answer.answer === 'yes' && expected === 'positive')
+	      || (answer.answer === 'no' && expected === 'negative')
+	}
+      default:
+	return true
+      }
+    })
+  })
+}
+
+
+export const hardFilteredPostsForAnswer = (
+    { posts, question, answer }: { posts:     Post[]
+				   question:  GekanatorQuestion
+				   answer:    GekanatorAnswerValue },
+): Post[] => {
+  if (!(questionSupportsAnswerBasedHardFiltering (question)))
+    return posts
+
+  if (!(answer === 'yes' || answer === 'no'))
+    return posts
+
+  return posts.filter (post => {
+    const side = learnedSemanticSideForPost (question, post)
+    return side === 'unknown'
+	|| (answer === 'yes' && side === 'positive')
+	|| (answer === 'no' && side === 'negative')
+  })
+}
+
+
+const concreteAnswerOptions: GekanatorAnswerValue[] = ['yes', 'no', 'partial', 'probably_no']
+
+
+export const allConcreteAnswerOptionsExhausted = (
+    posts:      Post[],
+    question:   GekanatorQuestion | null,
+): boolean => {
+  if (!(question))
+    return false
+
+  return concreteAnswerOptions.every (answer =>
+      hardFilteredPostsForAnswer ({ posts, question, answer }).length === 0)
+}
+
+
+const nextRecoveryTargetSize = (recoveryStepCount: number): number =>
+    6 * (2 ** recoveryStepCount)
+
+
+export const recoverCandidatePosts = (
+    { posts,
+      scores,
+      rejectedPostIds,
+      recoveredCandidatePosts,
+      eligiblePostIds,
+      answerCountAtRecovery,
+      recoveryStepCount }: { posts:                   Post[]
+			     scores:                  Map<number, number>
+			     rejectedPostIds:         Set<number>
+			     recoveredCandidatePosts: Map<number, RecoveredCandidateState>
+			     eligiblePostIds:         Set<number>
+			     answerCountAtRecovery:   number
+			     recoveryStepCount:       number },
+): { recoveredCandidatePosts: Map<number, RecoveredCandidateState>
+     recoveryStepCount:       number } | null => {
+  const recovered = new Map (recoveredCandidatePosts)
+  const targetSize = nextRecoveryTargetSize (recoveryStepCount)
+  const countedPostIds = new Set ([...eligiblePostIds, ...recovered.keys ()])
+  const addCount = targetSize - countedPostIds.size
+  if (addCount <= 0)
+    {
+      return { recoveredCandidatePosts: recovered,
+	       recoveryStepCount: recoveryStepCount + 1 }
+    }
+
+  const candidates =
+      posts
+      .filter (post => (!(rejectedPostIds.has (post.id))
+			&& !(eligiblePostIds.has (post.id))
+			&& !(recovered.has (post.id))))
+      .sort ((a, b) => ((scores.get (b.id) ?? Number.NEGATIVE_INFINITY)
+			- (scores.get (a.id) ?? Number.NEGATIVE_INFINITY)))
+      .slice (0, addCount)
+
+  if (candidates.length === 0)
+    return null
+
+  candidates.forEach (post => recovered.set (post.id, {
+      answerCountAtRecovery,
+      scoreAtRecovery: scores.get (post.id) ?? 0 }))
+
+  return { recoveredCandidatePosts: recovered,
+	   recoveryStepCount: recoveryStepCount + 1 }
+}

frontend/src/lib/gekanatorQuestionFilters.ts

@@ -0,0 +1,167 @@
+import { titleLengthMinimumForCondition } from '@/lib/gekanator'
+
+import type {
+    GekanatorAnswerLog,
+    GekanatorAnswerValue,
+    GekanatorQuestion,
+} from '@/lib/gekanator'
+
+
+export const monthForCondition = (
+    condition:  GekanatorQuestion['condition'],
+): number | null => {
+  if (condition.type === 'original-month')
+    return condition.month
+
+  if (condition.type !== 'original-month-day')
+    return null
+
+  const month = Number (condition.monthDay.split ('-')[0])
+  return Number.isInteger (month) ? month : null
+}
+
+
+const isTitleLengthContradiction = (
+    candidate:  GekanatorQuestion['condition'],
+    previous:   GekanatorQuestion['condition'],
+    answer:     GekanatorAnswerValue,
+): boolean => {
+  const candidateLength = titleLengthMinimumForCondition (candidate)
+  const previousLength = titleLengthMinimumForCondition (previous)
+  if (candidateLength === null || previousLength === null)
+    return false
+
+  switch (answer)
+  {
+  case 'yes':
+    return candidateLength <= previousLength
+  case 'no':
+    return candidateLength >= previousLength
+  default:
+    return false
+  }
+}
+
+
+const isQuestionRedundantAfterAnswers = (
+    question:  GekanatorQuestion,
+    answers:   GekanatorAnswerLog[],
+): boolean => answers.some (answer => {
+  const previous = answer.questionCondition
+  return previous !== undefined
+      && isTitleLengthContradiction (question.condition, previous, answer.answer)
+})
+
+
+const isSourceFactBlocked = (
+    candidate:  GekanatorQuestion['condition'],
+    previous:   GekanatorQuestion['condition'],
+    answer:     GekanatorAnswerValue,
+): boolean => {
+  if (candidate.type !== 'source' || previous.type !== 'source')
+    return false
+
+  switch (answer)
+  {
+  case 'yes':
+    return true
+  case 'no':
+    return candidate.host === previous.host
+  default:
+    return false
+  }
+}
+
+
+const isOriginalYearFactBlocked = (
+    candidate:  GekanatorQuestion['condition'],
+    previous:   GekanatorQuestion['condition'],
+    answer:     GekanatorAnswerValue,
+): boolean => {
+  if (candidate.type !== 'original-year' || previous.type !== 'original-year')
+    return false
+
+  switch (answer)
+  {
+  case 'yes':
+    return true
+  case 'no':
+    return candidate.year === previous.year
+  default:
+    return false
+  }
+}
+
+
+const isOriginalMonthFactBlocked = (
+    candidate:  GekanatorQuestion['condition'],
+    previous:   GekanatorQuestion['condition'],
+    answer:     GekanatorAnswerValue,
+): boolean => {
+  switch (answer)
+  {
+  case 'yes':
+    if (previous.type === 'original-month')
+      {
+	if (candidate.type === 'original-month')
+	  return true
+
+	if (candidate.type === 'original-month-day')
+	  return monthForCondition (candidate) !== previous.month
+
+	return false
+      }
+
+    if (previous.type === 'original-month-day')
+      return candidate.type === 'original-month'
+	  || candidate.type === 'original-month-day'
+
+    return false
+  case 'no':
+    if (previous.type === 'original-month')
+      {
+	if (candidate.type === 'original-month')
+	  return candidate.month === previous.month
+
+	if (candidate.type === 'original-month-day')
+	  return monthForCondition (candidate) === previous.month
+
+	return false
+      }
+
+    if (previous.type === 'original-month-day')
+      return candidate.type === 'original-month-day'
+	  && candidate.monthDay === previous.monthDay
+
+    return false
+  default:
+    return false
+  }
+}
+
+
+const isFactQuestionBlocked = (
+    candidate:  GekanatorQuestion['condition'],
+    previous:   GekanatorQuestion['condition'],
+    answer:     GekanatorAnswerValue,
+): boolean => {
+  if (!(answer === 'yes' || answer === 'no'))
+    return false
+
+  return isSourceFactBlocked (candidate, previous, answer)
+      || isOriginalYearFactBlocked (candidate, previous, answer)
+      || isOriginalMonthFactBlocked (candidate, previous, answer)
+}
+
+
+export const isQuestionHardFilteredAfterAnswers = (
+    question:  GekanatorQuestion,
+    answers:   GekanatorAnswerLog[],
+): boolean => answers.some (answer => {
+  const previous = answer.questionCondition
+  if (previous === undefined)
+    return false
+
+  return isQuestionRedundantAfterAnswers (question, [answer])
+      || isFactQuestionBlocked (question.condition, previous, answer.answer)
+})

frontend/src/lib/prefetchers.ts

@@ -17,6 +17,10 @@ const mWiki = match<{ title: string }> ('/wiki/:title')
 const mTag = match<{ id: string }> ('/tags/:id')
 
 
+const boolFromQuery = (value: string | null): boolean =>
+    ['1', 'true', 'on', 'yes', ''].includes ((value ?? '').toLowerCase ())
+
+
 const prefetchWikiPagesIndex: Prefetcher = async (qc, url) => {
   const title = url.searchParams.get ('title') ?? ''
 
@@ -156,13 +160,16 @@ const prefetchTagsIndex: Prefetcher = async (qc, url) => {
   const createdTo = url.searchParams.get ('created_to') ?? ''
   const updatedFrom = url.searchParams.get ('updated_from') ?? ''
   const updatedTo = url.searchParams.get ('updated_to') ?? ''
+  const deprecated = url.searchParams.has ('deprecated')
+      ? boolFromQuery (url.searchParams.get ('deprecated'))
+      : null
   const page = Number (url.searchParams.get ('page') || 1)
   const limit = Number (url.searchParams.get ('limit') || 20)
   const order = (url.searchParams.get ('order') ?? 'post_count:desc') as FetchTagsOrder
 
   const keys = {
       post, name, category, postCountGTE, postCountLTE, createdFrom, createdTo,
-      updatedFrom, updatedTo, page, limit, order }
+      updatedFrom, updatedTo, deprecated, page, limit, order }
 
   await qc.prefetchQuery ({
       queryKey: tagsKeys.index (keys),

frontend/src/lib/queryKeys.ts

@@ -9,8 +9,11 @@ export const postsKeys = {
 		  ['posts', 'changes', p] as const }
 
 export const gekanatorKeys = {
-    root:   ['gekanator'] as const,
-    posts:  () => ['gekanator', 'posts'] as const }
+    root:      ['gekanator'] as const,
+    posts:     () => ['gekanator', 'posts'] as const,
+    questions: () => ['gekanator', 'questions'] as const,
+    extraQuestions: (gameId: number, nonce: string) =>
+		       ['gekanator', 'games', gameId, 'extra-questions', nonce] as const }
 
 export const tagsKeys = {
     root:         ['tags'] as const,

frontend/src/lib/tags.test.ts

@@ -20,6 +20,7 @@ const baseParams: FetchTagsParams = {
   createdTo:    '',
   updatedFrom:  '',
   updatedTo:    '',
+  deprecated:   null,
   page:         1,
   limit:        30,
   order:        'updated_at:desc',
@@ -57,6 +58,20 @@ describe ('tags API functions', () => {
     )
   })
 
+  it.each ([
+    [true, '1'],
+    [false, '0'],
+  ] as const) ('maps deprecated=%s to %s', async (deprecated, expected) => {
+    api.apiGet.mockResolvedValueOnce ({ tags: [], count: 0 })
+
+    await fetchTags ({ ...baseParams, deprecated })
+
+    expect (api.apiGet).toHaveBeenCalledWith (
+        '/tags',
+        { params: expect.objectContaining ({ deprecated: expected }) },
+    )
+  })
+
   it ('returns null when tag fetches fail', async () => {
     api.apiGet.mockRejectedValueOnce (new Error ('missing'))
     api.apiGet.mockRejectedValueOnce (new Error ('missing'))

frontend/src/lib/tags.ts

@@ -10,7 +10,8 @@ import type { Deerjikist,
 
 export const fetchTags = async (
     { post, name, category, postCountGTE, postCountLTE, createdFrom, createdTo,
-      updatedFrom, updatedTo, page, limit, order }: FetchTagsParams,
+      updatedFrom, updatedTo, deprecated,
+      page, limit, order }: FetchTagsParams,
 ): Promise<{ tags:  Tag[]
 	     count: number }> =>
     await apiGet ('/tags', { params: {
@@ -23,6 +24,7 @@ export const fetchTags = async (
 	...(createdTo && { created_to: createdTo }),
 	...(updatedFrom && { updated_from: updatedFrom }),
 	...(updatedTo && { updated_to: updatedTo }),
+	...(deprecated != null && { deprecated: deprecated ? '1' : '0' }),
 	...(page && { page }),
 	...(limit && { limit }),
 	...(order && { order }) } })
@@ -64,7 +66,6 @@ export const fetchTagByName = async (name: string): Promise<Tag | null> => {
   }
 }
 
-
 export const fetchTagChanges = async (
     { id, page, limit }: {
 	id?:    string

frontend/src/pages/GekanatorPage.test.tsx

@@ -0,0 +1,240 @@
+import { readFileSync } from 'node:fs'
+import { resolve } from 'node:path'
+
+import { describe, expect, it } from 'vitest'
+
+import { isQuestionHardFilteredAfterAnswers } from '@/lib/gekanatorQuestionFilters'
+
+import type {
+    GekanatorAnswerLog,
+    GekanatorAnswerValue,
+    GekanatorQuestion,
+    GekanatorQuestionCondition,
+} from '@/lib/gekanator'
+
+
+const question = (
+    condition:  GekanatorQuestionCondition,
+): GekanatorQuestion => ({
+  id: `${ condition.type }:candidate`,
+  text: 'candidate?',
+  kind: condition.type === 'source'
+      ? 'source'
+      : condition.type.startsWith ('original-')
+	? 'original_date'
+	: condition.type.startsWith ('title-')
+	  ? 'title'
+	  : 'tag',
+  condition,
+  source: 'default',
+  priorityWeight: 1,
+  test: () => false,
+})
+
+
+const answer = (
+    condition:  GekanatorQuestionCondition,
+    value:      GekanatorAnswerValue,
+): GekanatorAnswerLog => ({
+  questionId: 'previous',
+  questionText: 'previous?',
+  questionCondition: condition,
+  answer: value,
+  originalAnswer: value,
+})
+
+
+const blocked = (
+    candidate:  GekanatorQuestionCondition,
+    previous:   GekanatorQuestionCondition,
+    value:      GekanatorAnswerValue,
+): boolean =>
+    isQuestionHardFilteredAfterAnswers (question (candidate), [answer (previous, value)])
+
+
+const gekanatorPageSource = readFileSync (
+    resolve (process.cwd (), 'src/pages/GekanatorPage.tsx'),
+    'utf8')
+
+const gekanatorBackdropSource = gekanatorPageSource.slice (
+    gekanatorPageSource.indexOf ('const GekanatorBackdrop'),
+    gekanatorPageSource.indexOf ('const expectedAnswerFor'))
+
+const gekanatorChooseQuestionSource = gekanatorPageSource.slice (
+    gekanatorPageSource.indexOf ('const chooseQuestion'),
+    gekanatorPageSource.indexOf ('const winningRunPriorityFor'))
+
+const gekanatorFallbackQuestionSource = gekanatorPageSource.slice (
+    gekanatorPageSource.indexOf ('const chooseFallbackQuestion'),
+    gekanatorPageSource.indexOf ('const shouldEnterGuessPhase'))
+
+
+describe('GekanatorBackdrop regression structure', () => {
+  it('keeps displayedBackdropMode as the render-time source of truth', () => {
+    expect(gekanatorBackdropSource).not.toContain ('isLeavingGuessBackdrop')
+    expect(gekanatorBackdropSource).not.toContain ('renderBackdropMode')
+    expect(gekanatorBackdropSource).not.toContain ('renderWinningRunCount')
+    expect(gekanatorBackdropSource).not.toContain ('renderThumbnails')
+    expect(gekanatorBackdropSource).not.toContain ('renderIsCrossfading')
+
+    expect(gekanatorBackdropSource).toContain (
+      "const renderedSettings = settingsForMode (displayedBackdropMode)")
+    expect(gekanatorBackdropSource).toContain (
+      'scaleForMode (displayedBackdropMode, displayedWinningRunCount)')
+    expect(gekanatorBackdropSource).toContain (
+      "backdropMode === 'guess' || displayedBackdropMode === 'guess'")
+  })
+
+  it('does not split guess into a separate renderer or force a remount', () => {
+    expect(gekanatorBackdropSource).not.toContain ('renderStaticGuessBackdrop')
+    expect(gekanatorBackdropSource).not.toContain ('guessZoomAnimationKey')
+    expect(gekanatorBackdropSource).not.toContain ('shouldAnimateGuessZoomIn')
+    expect(gekanatorBackdropSource).not.toContain ('previousBackdropModeRef')
+    expect(gekanatorBackdropSource).not.toContain (
+      'if (isGuessPresentation && guessThumbnail)')
+  })
+
+  it('keeps tile keys independent from backdrop mode', () => {
+    expect(gekanatorBackdropSource).toContain ('key={duplicate}')
+    expect(gekanatorBackdropSource).toContain ('key={`${ duplicate }:${ index }`}')
+    expect(gekanatorBackdropSource).not.toMatch (/key=\{`\$\{\s*mode/)
+    expect(gekanatorBackdropSource).not.toMatch (/key=\{`\$\{\s*displayedBackdropMode/)
+  })
+
+  it('keeps guess on the shared scale, x, and y animation path', () => {
+    expect(gekanatorBackdropSource).toContain ('animate={{ scale: renderedScale')
+    expect(gekanatorBackdropSource).toContain (
+      "x: displayedBackdropMode === 'guess' ? guessFocusOffset.x : '0%'")
+    expect(gekanatorBackdropSource).toContain (
+      "y: displayedBackdropMode === 'guess' ? guessFocusOffset.y : '0%'")
+  })
+})
+
+
+describe('Gekanator question selection regression structure', () => {
+  it('prefers normal questions after user_suggested quota has been met', () => {
+    const normalFallbackIndex = gekanatorChooseQuestionSource.indexOf (
+      'else if (normalPool.length > 0)')
+    const effectiveFallbackIndex = gekanatorChooseQuestionSource.indexOf (
+      'else if (effectiveUserSuggestedPool.length > 0)')
+
+    expect(normalFallbackIndex).toBeGreaterThan(0)
+    expect(effectiveFallbackIndex).toBeGreaterThan(0)
+    expect(normalFallbackIndex).toBeLessThan(effectiveFallbackIndex)
+  })
+
+  it('does not let fallback questions bypass user_suggested purpose tracking', () => {
+    expect(gekanatorFallbackQuestionSource).toContain (
+      "question.source !== 'user_suggested'")
+  })
+
+  it('does not show a fixed extra-question count in the extra learning UI', () => {
+    expect(gekanatorPageSource).not.toContain ('追加で 2 問まで答えてください。')
+    expect(gekanatorPageSource).toContain ('追加で質問に答えてください。')
+  })
+})
+
+
+describe('isQuestionHardFilteredAfterAnswers', () => {
+  it('blocks only contradictory or redundant month questions after a yes answer', () => {
+    const previous: GekanatorQuestionCondition = { type: 'original-month', month: 12 }
+
+    expect(blocked ({ type: 'original-month', month: 12 }, previous, 'yes')).toBe(true)
+    expect(blocked ({ type: 'original-month', month: 2 }, previous, 'yes')).toBe(true)
+    expect(blocked ({ type: 'original-month-day', monthDay: '2-14' }, previous, 'yes'))
+      .toBe(true)
+    expect(blocked ({ type: 'original-month-day', monthDay: '12-25' }, previous, 'yes'))
+      .toBe(false)
+    expect(blocked ({ type: 'original-year', year: 2024 }, previous, 'yes')).toBe(false)
+    expect(blocked ({ type: 'source', host: 'example.com' }, previous, 'yes')).toBe(false)
+    expect(blocked ({ type: 'tag', key: 'character:喜多郁代' }, previous, 'yes')).toBe(false)
+  })
+
+  it('blocks same-month facts after a no answer', () => {
+    const previous: GekanatorQuestionCondition = { type: 'original-month', month: 12 }
+
+    expect(blocked ({ type: 'original-month', month: 12 }, previous, 'no')).toBe(true)
+    expect(blocked ({ type: 'original-month', month: 2 }, previous, 'no')).toBe(false)
+    expect(blocked ({ type: 'original-month-day', monthDay: '12-25' }, previous, 'no'))
+      .toBe(true)
+    expect(blocked ({ type: 'original-month-day', monthDay: '2-14' }, previous, 'no'))
+      .toBe(false)
+  })
+
+  it('blocks all month and month-day questions after a month-day yes answer', () => {
+    const previous: GekanatorQuestionCondition = {
+      type: 'original-month-day',
+      monthDay: '12-25',
+    }
+
+    expect(blocked ({ type: 'original-month', month: 12 }, previous, 'yes')).toBe(true)
+    expect(blocked ({ type: 'original-month', month: 2 }, previous, 'yes')).toBe(true)
+    expect(blocked ({ type: 'original-month-day', monthDay: '12-25' }, previous, 'yes'))
+      .toBe(true)
+    expect(blocked ({ type: 'original-month-day', monthDay: '12-26' }, previous, 'yes'))
+      .toBe(true)
+  })
+
+  it('blocks the same month-day only after a month-day no answer', () => {
+    const previous: GekanatorQuestionCondition = {
+      type: 'original-month-day',
+      monthDay: '12-25',
+    }
+
+    expect(blocked ({ type: 'original-month-day', monthDay: '12-25' }, previous, 'no'))
+      .toBe(true)
+    expect(blocked ({ type: 'original-month-day', monthDay: '12-26' }, previous, 'no'))
+      .toBe(false)
+    expect(blocked ({ type: 'original-month', month: 12 }, previous, 'no')).toBe(false)
+  })
+
+  it('blocks year and source as single-value facts', () => {
+    expect(blocked (
+      { type: 'original-year', year: 2025 },
+      { type: 'original-year', year: 2024 },
+      'yes',
+    )).toBe(true)
+    expect(blocked (
+      { type: 'original-year', year: 2024 },
+      { type: 'original-year', year: 2024 },
+      'no',
+    )).toBe(true)
+    expect(blocked (
+      { type: 'source', host: 'b.example' },
+      { type: 'source', host: 'a.example' },
+      'yes',
+    )).toBe(true)
+    expect(blocked (
+      { type: 'source', host: 'b.example' },
+      { type: 'source', host: 'a.example' },
+      'no',
+    )).toBe(false)
+  })
+
+  it('does not hard-filter partial, probably_no, or unknown fact answers', () => {
+    const previous: GekanatorQuestionCondition = { type: 'original-month', month: 12 }
+    const candidate: GekanatorQuestionCondition = { type: 'original-month', month: 2 }
+
+    expect(blocked (candidate, previous, 'partial')).toBe(false)
+    expect(blocked (candidate, previous, 'probably_no')).toBe(false)
+    expect(blocked (candidate, previous, 'unknown')).toBe(false)
+  })
+
+  it('keeps title-length hard redundancy for yes and no only', () => {
+    const previous: GekanatorQuestionCondition = {
+      type: 'title-length-at-least',
+      length: 30,
+    }
+
+    expect(blocked ({ type: 'title-length-at-least', length: 20 }, previous, 'yes'))
+      .toBe(true)
+    expect(blocked ({ type: 'title-length-at-least', length: 40 }, previous, 'yes'))
+      .toBe(false)
+    expect(blocked ({ type: 'title-length-at-least', length: 40 }, previous, 'no'))
+      .toBe(true)
+    expect(blocked ({ type: 'title-length-at-least', length: 20 }, previous, 'no'))
+      .toBe(false)
+    expect(blocked ({ type: 'title-length-at-least', length: 20 }, previous, 'partial'))
+      .toBe(false)
+  })
+})

frontend/src/pages/tags/TagDetailPage.tsx

@@ -19,7 +19,12 @@ import type { FC, FormEvent } from 'react'
 
 import type { Category, Tag } from '@/types'
 
-type TagFormField = 'name' | 'category' | 'aliases' | 'parentTags'
+type TagFormField =
+    | 'name'
+    | 'category'
+    | 'aliases'
+    | 'parentTags'
+    | 'deprecated'
 
 
 const TagDetailPage: FC = () => {
@@ -35,6 +40,7 @@ const TagDetailPage: FC = () => {
   const [category, setCategory] = useState<Category> ('general')
   const [aliases, setAliases] = useState ('')
   const [parentTags, setParentTags] = useState ('')
+  const [deprecated, setDeprecated] = useState (false)
   const [disabled, setDisabled] = useState (true)
   const { baseErrors, fieldErrors, clearValidationErrors, applyValidationError } =
       useValidationErrors<TagFormField> ()
@@ -50,6 +56,7 @@ const TagDetailPage: FC = () => {
     formData.append ('category', category)
     formData.append ('aliases', aliases)
     formData.append ('parent_tags', parentTags)
+    formData.append ('deprecated', deprecated ? '1' : '0')
 
     try
     {
@@ -59,6 +66,7 @@ const TagDetailPage: FC = () => {
       setCategory (data.category as Category)
       setAliases (data.aliases.join (' '))
       setParentTags (data.parents.map (t => t.name).join (' '))
+      setDeprecated (Boolean (data.deprecatedAt))
 
       qc.invalidateQueries ({ queryKey: postsKeys.root })
       qc.invalidateQueries ({ queryKey: tagsKeys.root })
@@ -82,6 +90,7 @@ const TagDetailPage: FC = () => {
     setCategory (tag.category as Category)
     setAliases (tag.aliases.join (' '))
     setParentTags (tag.parents.map (t => t.name).join (' '))
+    setDeprecated (Boolean (tag.deprecatedAt))
     setDisabled (tag.category === 'nico')
   }, [tag])
 
@@ -165,6 +174,17 @@ const TagDetailPage: FC = () => {
 		      </>)}
 		</FormField>
 
+		<FormField label="廃止済" messages={fieldErrors.deprecated}>
+		  {({ describedBy, invalid }) => (
+		      <input
+			  type="checkbox"
+			  disabled={disabled}
+			  checked={deprecated}
+			  onChange={e => setDeprecated (e.target.checked)}
+			  aria-describedby={describedBy}
+			  aria-invalid={invalid}/>)}
+		</FormField>
+
 		<div className="py-3">
 		  <button
 		      type="submit"

frontend/src/pages/tags/TagHistoryPage.tsx

@@ -20,17 +20,28 @@ import type { FC } from 'react'
 
 const renderDiff = (diff: { current: string | null; prev: string | null }) => (
     <>
-      {(diff.prev && diff.prev !== diff.current) && (
+      {diff.prev !== diff.current
+       ? (
 	  <>
 	    <del className="text-red-600 dark:text-red-400">
-	      {diff.prev}
+	      {diff.prev && <>{diff.prev}<br/></>}
 	    </del>
-	    {diff.current && <br/>}
-	  </>)}
-      {diff.current}
+	    <ins className="text-green-600 dark:text-green-400">
+	      {diff.current}
+	    </ins>
+	  </>)
+       : diff.current}
     </>)
 
 
+const tagStateLabel = (deprecatedAt: string | null) => deprecatedAt ? '廃止' : ''
+
+
+const renderStateDiff = (diff: { current: string | null; prev: string | null }) =>
+    renderDiff ({ current: tagStateLabel (diff.current),
+		  prev: tagStateLabel (diff.prev) })
+
+
 const TagHistoryPage: FC = () => {
   const location = useLocation ()
   const query = new URLSearchParams (location.search)
@@ -72,6 +83,8 @@ const TagHistoryPage: FC = () => {
 		    <col className="w-96"/>
 		    {/* カテゴリ */}
 		    <col className="w-96"/>
+		    {/* 状態 */}
+		    <col className="w-32"/>
 		    {/* 別名 */}
 		    <col className="w-[48rem]"/>
 		    {/* 上位タグ */}
@@ -87,6 +100,7 @@ const TagHistoryPage: FC = () => {
 		      <th className="p-2 text-left">版</th>
 		      <th className="p-2 text-left">名称</th>
 		      <th className="p-2 text-left">カテゴリ</th>
+		      <th className="p-2 text-left">状態</th>
 		      <th className="p-2 text-left">別名</th>
 		      <th className="p-2 text-left">上位タグ</th>
 		      <th className="p-2 text-left">更新日時</th>
@@ -106,6 +120,9 @@ const TagHistoryPage: FC = () => {
 				prev: (change.category.prev
 				       && CATEGORY_NAMES[change.category.prev]) })}
 			  </td>
+			  <td className="p-2 break-all">
+			    {renderStateDiff (change.deprecatedAt)}
+			  </td>
 			  <td className="p-2">
 			    {change.aliases.map ((tag, i) => (
 				tag.type === 'added'
@@ -178,6 +195,7 @@ const TagHistoryPage: FC = () => {
 					`/tags/${ change.tagId }`,
 					{ name: change.name.current,
 					  category: change.category.current,
+					  deprecated: change.deprecatedAt.current ? '1' : '0',
 					  aliases:
 					      change.aliases
 					      .filter (t => t.type !== 'removed')
@@ -211,4 +229,5 @@ const TagHistoryPage: FC = () => {
       </MainArea>)
 }
 
-export default TagHistoryPage
+
+export default TagHistoryPage

frontend/src/pages/tags/TagListPage.test.tsx

@@ -14,13 +14,22 @@ vi.mock ('@/lib/tags', () => tagsApi)
 describe ('TagListPage', () => {
   it ('loads tags from URL filters and renders the results table', async () => {
     tagsApi.fetchTags.mockResolvedValueOnce ({
-      tags: [buildTag ({ id: 7, name: '虹夏', category: 'character', postCount: 99 })],
+      tags: [buildTag ({
+        id: 7,
+        name: '虹夏',
+        category: 'character',
+        postCount: 99,
+        deprecatedAt: '2026-06-01T00:00:00.000Z',
+      })],
       count: 1,
     })
 
     renderWithProviders (
         <TagListPage/>,
-        { route: '/tags?name=%E8%99%B9&category=character&page=3&post_count_gte=5' },
+        {
+          route:
+              '/tags?name=%E8%99%B9&category=character&page=3&post_count_gte=5&deprecated=1',
+        },
     )
 
     await waitFor (() => {
@@ -30,6 +39,7 @@ describe ('TagListPage', () => {
             category:     'character',
             page:         3,
             postCountGTE: 5,
+            deprecated:   true,
           }),
       )
     })
@@ -38,6 +48,8 @@ describe ('TagListPage', () => {
         '/tags/7',
     )
     expect (screen.getAllByText ('キャラクター').length).toBeGreaterThan (0)
+    expect (screen.getAllByRole ('combobox')[1]).toHaveValue ('1')
+    expect (screen.getAllByText ('廃止')).toHaveLength (2)
   })
 
   it ('navigates to a normalized search URL on submit', async () => {
@@ -46,7 +58,9 @@ describe ('TagListPage', () => {
     renderWithProviders (<TagListPage/>, { route: '/tags' })
 
     fireEvent.change (screen.getByRole ('textbox'), { target: { value: '虹夏' } })
-    fireEvent.change (screen.getByRole ('combobox'), { target: { value: 'character' } })
+    fireEvent.change (screen.getAllByRole ('combobox')[0], {
+      target: { value: 'character' },
+    })
     fireEvent.submit (screen.getByRole ('button', { name: '検索' }).closest ('form')!)
 
     await waitFor (() => {

frontend/src/pages/tags/TagListPage.tsx

@@ -29,6 +29,13 @@ const setIf = (qs: URLSearchParams, k: string, v: string | null) => {
 }
 
 
+const boolFromQuery = (value: string | null): boolean =>
+    ['1', 'true', 'on', 'yes', ''].includes ((value ?? '').toLowerCase ())
+
+
+const tagStateLabel = (deprecatedAt: string | null) => deprecatedAt ? '廃止' : ''
+
+
 const TagListPage: FC = () => {
   const location = useLocation ()
 
@@ -48,6 +55,9 @@ const TagListPage: FC = () => {
   const qCreatedTo = query.get ('created_to') ?? ''
   const qUpdatedFrom = query.get ('updated_from') ?? ''
   const qUpdatedTo = query.get ('updated_to') ?? ''
+  const qDeprecated = query.has ('deprecated')
+      ? boolFromQuery (query.get ('deprecated'))
+      : null
   const order = (query.get ('order') || 'post_count:desc') as FetchTagsOrder
 
   const [name, setName] = useState ('')
@@ -58,6 +68,7 @@ const TagListPage: FC = () => {
   const [createdTo, setCreatedTo] = useState<string | null> (null)
   const [updatedFrom, setUpdatedFrom] = useState<string | null> (null)
   const [updatedTo, setUpdatedTo] = useState<string | null> (null)
+  const [deprecated, setDeprecated] = useState<boolean | null> (null)
 
   const keys = {
       page, limit, order,
@@ -69,7 +80,8 @@ const TagListPage: FC = () => {
       createdFrom: qCreatedFrom,
       createdTo: qCreatedTo,
       updatedFrom: qUpdatedFrom,
-      updatedTo: qUpdatedTo }
+      updatedTo: qUpdatedTo,
+      deprecated: qDeprecated }
   const { data, isLoading: loading } = useQuery ({
       queryKey: tagsKeys.index (keys),
       queryFn: () => fetchTags (keys) })
@@ -85,10 +97,11 @@ const TagListPage: FC = () => {
     setCreatedTo (qCreatedTo)
     setUpdatedFrom (qUpdatedFrom)
     setUpdatedTo (qUpdatedTo)
+    setDeprecated (qDeprecated)
 
     document.querySelector ('table')?.scrollIntoView ({ behavior: 'smooth' })
   }, [location.search, qCategory, qCreatedFrom, qCreatedTo, qName, qPostCountGTE,
-      qPostCountLTE, qUpdatedFrom, qUpdatedTo])
+      qPostCountLTE, qUpdatedFrom, qUpdatedTo, qDeprecated])
 
   const handleSearch = (e: FormEvent) => {
     e.preventDefault ()
@@ -104,6 +117,8 @@ const TagListPage: FC = () => {
     setIf (qs, 'created_to', createdTo)
     setIf (qs, 'updated_from', updatedFrom)
     setIf (qs, 'updated_to', updatedTo)
+    if (deprecated != null)
+      qs.set ('deprecated', deprecated ? '1' : '0')
     qs.set ('page', '1')
     qs.set ('order', order)
 
@@ -201,6 +216,21 @@ const TagListPage: FC = () => {
 		  </>)}
 	    </FormField>
 
+	    <FormField label="状態">
+	      {({ invalid }) => (
+		  <select
+		      value={deprecated == null ? '' : (deprecated ? '1' : '0')}
+		      onChange={e => setDeprecated (
+			  e.target.value === ''
+			  ? null
+			  : e.target.value === '1')}
+		      className={inputClass (invalid)}>
+		    <option value="">&nbsp;</option>
+		    <option value="0">有効</option>
+		    <option value="1">廃止</option>
+		  </select>)}
+	    </FormField>
+
 	    <div className="py-3">
 	      <button
 		  type="submit"
@@ -219,6 +249,7 @@ const TagListPage: FC = () => {
 		    <col className="w-72"/>
 		    <col className="w-16"/>
 		    <col className="w-48"/>
+		    <col className="w-32"/>
 		    <col className="w-72"/>
 		    <col className="w-48"/>
 		    <col className="w-56"/>
@@ -249,6 +280,7 @@ const TagListPage: FC = () => {
 			    currentOrder={order}
 			    defaultDirection={defaultDirection}/>
 		      </th>
+		      <th className="p-2 text-left whitespace-nowrap">状態</th>
 		      <th className="p-2 text-left whitespace-nowrap">別名</th>
 		      <th className="p-2 text-left whitespace-nowrap">上位タグ</th>
 		      <th className="p-2 text-left whitespace-nowrap">
@@ -280,6 +312,7 @@ const TagListPage: FC = () => {
 			  </td>
 			  <td className="p-2 text-right">{row.postCount}</td>
 			  <td className="p-2">{CATEGORY_NAMES[row.category]}</td>
+			  <td className="p-2">{tagStateLabel (row.deprecatedAt)}</td>
 			  <td className="p-2">{row.aliases.join (' ')}</td>
 			  <td className="p-2">
 			    {row.parents.map (t => (

frontend/src/pages/wiki/WikiDetailPage.test.tsx

@@ -0,0 +1,54 @@
+import { screen } from '@testing-library/react'
+import { Route, Routes } from 'react-router-dom'
+import { describe, expect, it, vi } from 'vitest'
+
+import WikiDetailPage from '@/pages/wiki/WikiDetailPage'
+import { buildTag, buildWikiPage } from '@/test/factories'
+import { renderWithProviders } from '@/test/render'
+
+const wikiApi = vi.hoisted (() => ({
+  fetchWikiPage:        vi.fn (),
+  fetchWikiPageByTitle: vi.fn (),
+}))
+
+const tagsApi = vi.hoisted (() => ({
+  fetchTagByName: vi.fn (),
+}))
+
+const postsApi = vi.hoisted (() => ({
+  fetchPosts: vi.fn (),
+}))
+
+vi.mock ('@/lib/wiki', () => wikiApi)
+vi.mock ('@/lib/tags', () => tagsApi)
+vi.mock ('@/lib/posts', () => postsApi)
+
+describe ('WikiDetailPage', () => {
+  it ('renders deprecated state outside the wiki title link', async () => {
+    wikiApi.fetchWikiPageByTitle.mockResolvedValueOnce (buildWikiPage ({
+      title:        '旧タグ',
+      deprecatedAt: '2026-06-01T00:00:00.000Z',
+    }))
+    tagsApi.fetchTagByName.mockResolvedValueOnce (buildTag ({
+      name:         '旧タグ',
+      deprecatedAt: '2026-06-01T00:00:00.000Z',
+    }))
+    postsApi.fetchPosts.mockResolvedValueOnce ({ posts: [], count: 0 })
+
+    renderWithProviders (
+        <Routes>
+          <Route path="/wiki/:title" element={<WikiDetailPage/>}/>
+        </Routes>,
+        { route: '/wiki/%E6%97%A7%E3%82%BF%E3%82%B0' },
+    )
+
+    const marker = await screen.findByText ('（廃止）')
+    const heading = marker.closest ('h1')
+    const link = screen.getByRole ('link', { name: '旧タグ' })
+
+    expect (heading).not.toBeNull ()
+    expect (heading!).toHaveTextContent ('旧タグ（廃止）')
+    expect (link).toBeInTheDocument ()
+    expect (marker.closest ('a')).toBeNull ()
+  })
+})

frontend/src/pages/wiki/WikiDetailPage.tsx

@@ -39,6 +39,7 @@ const WikiDetailPage: FC = () => {
       queryFn:  () => fetchWikiPageByTitle (title, { version }) })
 
   const effectiveTitle = wikiPage?.title ?? title
+  const deprecated = wikiPage?.deprecatedAt != null
 
   const { data: tag } = useQuery ({
       enabled:  Boolean (effectiveTitle),
@@ -88,7 +89,7 @@ const WikiDetailPage: FC = () => {
   return (
       <MainArea>
 	<Helmet>
-	  <title>{`${ title } Wiki | ${ SITE_TITLE }`}</title>
+	  <title>{`${ effectiveTitle }${ deprecated ? '（廃止）' : '' } Wiki | ${ SITE_TITLE }`}</title>
 	  {!(wikiPage?.body) && <meta name="robots" content="noindex"/>}
 	</Helmet>
 
@@ -110,10 +111,13 @@ const WikiDetailPage: FC = () => {
 
 	<article className="prose dark:prose-invert mx-auto p-4">
 	  <h1 className="prose-a:no-underline">
-	    <TagLink tag={tag ?? defaultTag}
+	    <TagLink tag={tag ?? { ...defaultTag,
+				   name: effectiveTitle,
+				   deprecatedAt: wikiPage?.deprecatedAt ?? null }}
 		     withWiki={false}
 		     withCount={false}
 		     {...(version && { to: `/wiki/${ encodeURIComponent (title) }` })}/>
+	    {deprecated && <span>（廃止）</span>}
 	  </h1>
 	  {loading ? <div>Loading...</div> : <WikiBody title={title} body={wikiPage?.body}/>}
 

frontend/src/pages/wiki/WikiDiffPage.test.tsx

@@ -16,6 +16,7 @@ describe ('WikiDiffPage', () => {
     api.apiGet.mockResolvedValueOnce ({
       wikiPageId:      3,
       title:           '差分対象',
+      deprecatedAt:    null,
       olderRevisionId: 1,
       newerRevisionId: 2,
       diff: [
@@ -43,4 +44,26 @@ describe ('WikiDiffPage', () => {
     expect (screen.getByText ('added line')).toBeInTheDocument ()
     expect (screen.getByText ('removed line')).toBeInTheDocument ()
   })
+
+  it ('appends deprecated state to the wiki title', async () => {
+    api.apiGet.mockResolvedValueOnce ({
+      wikiPageId:      3,
+      title:           '廃止 Wiki',
+      deprecatedAt:    '2026-06-01T00:00:00.000Z',
+      olderRevisionId: 1,
+      newerRevisionId: 2,
+      diff:            [],
+    })
+
+    renderWithProviders (
+        <Routes>
+          <Route path="/wiki/:id/diff" element={<WikiDiffPage/>}/>
+        </Routes>,
+        { route: '/wiki/3/diff?from=1&to=2' },
+    )
+
+    expect (await screen.findByRole ('heading', {
+      name: '廃止 Wiki（廃止）',
+    })).toBeInTheDocument ()
+  })
 })

frontend/src/pages/wiki/WikiDiffPage.tsx

@@ -23,6 +23,9 @@ const WikiDiffPage: FC = () => {
   const query = new URLSearchParams (location.search)
   const from = query.get ('from')
   const to = query.get ('to')
+  const displayTitle = diff
+      ? `${ diff.title }${ diff.deprecatedAt != null ? '（廃止）' : '' }`
+      : ''
 
   useEffect (() => {
     void (async () => {
@@ -33,9 +36,9 @@ const WikiDiffPage: FC = () => {
   return (
       <MainArea>
 	<Helmet>
-	  <title>{`Wiki 差分: ${ diff?.title } | ${ SITE_TITLE }`}</title>
+	  <title>{`Wiki 差分: ${ displayTitle } | ${ SITE_TITLE }`}</title>
 	</Helmet>
-	<PageTitle>{diff?.title}</PageTitle>
+	<PageTitle>{displayTitle}</PageTitle>
 	<div className="prose mx-auto p-4">
 	  {diff
 	   ? (

frontend/src/pages/wiki/WikiHistoryPage.test.tsx

@@ -0,0 +1,38 @@
+import { screen } from '@testing-library/react'
+import { describe, expect, it, vi } from 'vitest'
+
+import WikiHistoryPage from '@/pages/wiki/WikiHistoryPage'
+import { renderWithProviders } from '@/test/render'
+
+const api = vi.hoisted (() => ({
+  apiGet: vi.fn (),
+}))
+
+vi.mock ('@/lib/api', () => api)
+
+describe ('WikiHistoryPage', () => {
+  it ('renders deprecated state outside the wiki title link', async () => {
+    api.apiGet.mockResolvedValueOnce ([{
+      revisionId:  2,
+      pred:        1,
+      succ:        null,
+      wikiPage:    {
+	id:           3,
+	title:        '旧タグ',
+	deprecatedAt: '2026-06-01T00:00:00.000Z',
+      },
+      user:        { id: 4, name: 'tester' },
+      kind:        'content',
+      message:     'updated',
+      timestamp:   '2026-06-02T00:00:00.000Z',
+    }])
+
+    renderWithProviders (<WikiHistoryPage/>)
+
+    const link = await screen.findByRole ('link', { name: '旧タグ' })
+    const marker = screen.getByText ('（廃止）')
+
+    expect (link).toHaveAttribute ('href', '/wiki/%E6%97%A7%E3%82%BF%E3%82%B0?version=2')
+    expect (marker.closest ('a')).toBeNull ()
+  })
+})

frontend/src/pages/wiki/WikiHistoryPage.tsx

@@ -59,6 +59,7 @@ const WikiHistoryPage: FC = () => {
 			to={`/wiki/${ encodeURIComponent (change.wikiPage.title) }?version=${ change.revisionId }`}>
 		      {change.wikiPage.title}
 		    </PrefetchLink>
+		    {change.wikiPage.deprecatedAt != null && <span>（廃止）</span>}
 		  </td>
 		  <td className="p-2">
 		    {change.pred == null ? '新規' : '更新'}

frontend/src/pages/wiki/WikiSearchPage.test.tsx

@@ -42,4 +42,21 @@ describe ('WikiSearchPage', () => {
     })
     expect (await screen.findByRole ('link', { name: '検索結果' })).toBeInTheDocument ()
   })
+
+  it ('marks deprecated wiki tags in the result title', async () => {
+    api.apiGet.mockResolvedValueOnce ([
+        buildWikiPage ({
+            title:        '旧タグ',
+            deprecatedAt: '2026-06-01T00:00:00.000Z',
+        }),
+    ])
+
+    renderWithProviders (<WikiSearchPage/>)
+
+    const link = await screen.findByRole ('link', { name: '旧タグ' })
+    const marker = screen.getByText ('（廃止）')
+
+    expect (link).toBeInTheDocument ()
+    expect (marker.closest ('a')).toBeNull ()
+  })
 })

frontend/src/pages/wiki/WikiSearchPage.tsx

@@ -86,6 +86,7 @@ const WikiSearchPage: FC = () => {
 		      <PrefetchLink to={`/wiki/${ encodeURIComponent (page.title) }`}>
 			{page.title}
 		      </PrefetchLink>
+		      {page.deprecatedAt != null && <span>（廃止）</span>}
 		    </td>
 		    <td className="p-2">
 		      {dateString (page.updatedAt)}

frontend/src/test/factories.ts

@@ -13,6 +13,7 @@ export const buildTag = (overrides: Partial<Tag> = {}): Tag => ({
   id:             1,
   name:           'テストタグ',
   category:       'general',
+  deprecatedAt:   null,
   aliases:        [],
   parents:        [],
   postCount:      12,
@@ -57,6 +58,7 @@ export const buildUser = (overrides: Partial<User> = {}): User => ({
 export const buildWikiPage = (overrides: Partial<WikiPage> = {}): WikiPage => ({
   id:            1,
   title:         'テストWiki',
+  deprecatedAt:  null,
   createdUserId: 1,
   updatedUserId: 1,
   createdAt:     '2026-01-02T03:04:05.000Z',

frontend/src/types.ts

@@ -39,18 +39,19 @@ export type FetchTagsOrderField =
     | 'updated_at'
 
 export type FetchTagsParams = {
-    post:         number | null
-    name:         string
-    category:     Category | null
-    postCountGTE: number
-    postCountLTE: number | null
-    createdFrom:  string
-    createdTo:    string
-    updatedFrom:  string
-    updatedTo:    string
-    page:         number
-    limit:        number
-    order:        FetchTagsOrder }
+    post:           number | null
+    name:           string
+    category:       Category | null
+    postCountGTE:   number
+    postCountLTE:   number | null
+    createdFrom:    string
+    createdTo:      string
+    updatedFrom:    string
+    updatedTo:      string
+    deprecated:     boolean | null
+    page:           number
+    limit:          number
+    order:          FetchTagsOrder }
 
 export type FetchNicoTagsParams = {
     name:       string
@@ -139,6 +140,10 @@ export type Post = {
     title:                  string | null
     thumbnail:              string | null
     thumbnailBase:          string | null
+    postSimilarityEdges?:   {
+			      targetPostId: number
+			      cos:          number
+			  }[]
     tags:                   Tag[]
     parentPosts?:           Post[]
     childPosts?:            Post[]
@@ -192,6 +197,7 @@ export type Tag = {
     id:             number
     name:           string
     category:       Category
+    deprecatedAt:   string | null
     aliases:        string[]
     parents:        Tag[]
     postCount:      number
@@ -209,6 +215,7 @@ export type TagVersion = {
     eventType:              'create' | 'update' | 'discard' | 'restore'
     name:                   { current: string; prev: string | null }
     category:               { current: Category; prev: Category | null }
+    deprecatedAt:           { current: string | null; prev: string | null }
     aliases:                { name: string; type: 'context' | 'added' | 'removed' }[]
     parentTags:             { tag: Tag; type: 'context' | 'added' | 'removed' }[]
     createdAt:              string
@@ -292,6 +299,7 @@ export type ViewFlagBehavior = typeof ViewFlagBehavior[keyof typeof ViewFlagBeha
 export type WikiPage = {
     id:             number
     title:          string
+    deprecatedAt:   string | null
     createdUserId:  number
     updatedUserId:  number
     createdAt:      string
@@ -305,7 +313,7 @@ export type WikiPageChange = {
     revisionId: number
     pred:       number | null
     succ:       null
-    wikiPage:   Pick<WikiPage, 'id' | 'title'>
+    wikiPage:   Pick<WikiPage, 'id' | 'title' | 'deprecatedAt'>
     user:       Pick<User, 'id' | 'name'>
     kind:       'content' | 'redirect'
     message:    string | null
@@ -314,6 +322,7 @@ export type WikiPageChange = {
 export type WikiPageDiff = {
     wikiPageId:       number
     title:            string
+    deprecatedAt:     string | null
     olderRevisionId:  number | null
     newerRevisionId:  number
     diff:             WikiPageDiffDiff[] }

frontend/tsconfig.app.json

@@ -27,5 +27,6 @@
       "@/*": ["*"]
     }
   },
-  "include": ["src"]
+  "include": ["src"],
+  "exclude": ["src/**/*.test.ts", "src/**/*.test.tsx", "src/test"]
 }