グカネータ作成 / ウィニング・ラン修正 (#41 ) (#366 )

Reviewed-on: #366 Co-authored-by: miteruzo <miteruzo@naver.com> Co-committed-by: miteruzo <miteruzo@naver.com>
グカネータ / 質問パターン見直し (#41 ) (#365 )
2026-06-12 02:08:59 +09:00 · 2026-06-12 01:35:31 +09:00 · 2026-06-11 23:21:44 +09:00 · 2026-06-10 23:43:50 +09:00 · 2026-06-10 23:33:56 +09:00 · 2026-06-07 09:08:41 +09:00
@@ -126,12 +126,16 @@ npm run preview
 - 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.
 - Do not add production dependencies without explicit approval.
+- Do not create, modify, or run tests unless the user explicitly asks for
+  test work. When the user asks for tests, keep working and rerun them until
+  they pass or the remaining failure is clearly blocked.

 ## Backend rules

 - Inspect existing routes, controllers, models, services, and specs before
  editing backend behavior.
- For API behavior changes, add or update request specs under `backend/spec/requests`.
+- For API behavior changes, add or update request specs under
+  `backend/spec/requests` only when the user explicitly asks for tests.
 - Prefer RSpec for new backend tests; existing minitest files under
  `backend/test` do not make minitest the default for new coverage.
 - Do not weaken authentication, BAN user checks, or IP BAN checks.
@@ -211,10 +215,11 @@ function PostFormTagsArea ({ tags, setTags }: Props) {
  `node_modules`, `dist`, `tmp`, `log`, and `storage` unless explicitly needed.
 - Before touching wiki, tag, versioning, BAN, IP BAN, or authentication
  behavior, inspect the related request specs and service objects.
- If frontend code changes, run the existing frontend verification commands
-  that apply: `npm run build`, `npm run lint`, and `npm run test:run`.
- If backend code changes, run the relevant RSpec command; for broad backend
-  changes, run `bundle exec rspec`.
+- If frontend code changes, run only non-test verification commands that
+  apply, such as `npm run build` and `npm run lint`. Run `npm run test:run`
+  only when the user explicitly asks for tests.
+- If backend code changes, do not run RSpec unless the user explicitly asks
+  for tests.
 - If a verification command cannot be run or fails, report the exact command and failure.

 ## Completion criteria
@@ -222,7 +227,8 @@ function PostFormTagsArea ({ tags, setTags }: Props) {
 A task is complete only when:

 - implementation is complete,
- relevant verification commands pass, or failures are clearly explained,
+- relevant non-test verification commands pass, or failures are clearly
+  explained,
 - unrelated files are not changed,
 - migrations and schema are consistent when schema changes are made,
 - user-facing behavior is documented when needed.
@@ -47,6 +47,10 @@ bundle exec rspec

 If a command cannot be run or fails, report the exact command and failure.

+Do not create, modify, or run tests unless the user explicitly asks for test
+work. When the user asks for tests, keep working and rerun them until they
+pass or the remaining failure is clearly blocked.
+
 ## Rails structure

 - `app/controllers`: API controllers.
@@ -116,7 +120,8 @@ service, representation, and spec.
 - `User#banned?` and `IpAddress#banned?` check `banned_at.present?`.
 - Do not weaken BAN or IP BAN behavior.
 - If changing request authentication or controller before actions, add or
-  update request specs covering banned users and banned IP addresses.
+  update request specs covering banned users and banned IP addresses only when
+  the user explicitly asks for tests.

 ## RSpec

@@ -130,8 +135,9 @@ service, representation, and spec.
 - `AuthHelper#sign_in_as(user)` stubs
  `ApplicationController#current_user`; use it when matching existing
  request spec style.
- Add or update request specs for API behavior changes, especially status
-  codes, permissions, response shape, and version conflict behavior.
+- Add or update request specs for API behavior changes only when the user
+  explicitly asks for tests, especially status codes, permissions, response
+  shape, and version conflict behavior.

 ## Migrations

@@ -164,7 +170,8 @@ service, representation, and spec.
  the record `version_no`.
 - Do not update versioned records without considering whether a version snapshot must be created.
 - For optimistic concurrency paths, preserve `base_version_no`, `force`, and
-  `merge` semantics and cover conflicts in request specs.
+  `merge` semantics. Cover conflicts in request specs only when the user
+  explicitly asks for tests.

 ## Domain cautions

@@ -0,0 +1,140 @@
+class GekanatorGamesController < ApplicationController
+  def create
+    return head :not_found unless current_user&.admin?
+
+    guessed_post_id = params.require(:guessed_post_id)
+    correct_post_id = params[:correct_post_id].presence
+    answers = params.require(:answers).as_json
+
+    game = GekanatorGame.new(
+        user: current_user,
+        guessed_post_id:,
+        correct_post_id:,
+        won: correct_post_id.present? && guessed_post_id.to_i == correct_post_id.to_i,
+        question_count: answers.length,
+        answers:)
+
+    if game.save
+      render json: { id: game.id }, status: :created
+    else
+      render json: { errors: game.errors.full_messages }, status: :unprocessable_entity
+    end
+  end
+
+  def extra_questions
+    return head :not_found unless current_user&.admin?
+
+    game = GekanatorGame.find_by(id: params[:id])
+    return head :not_found unless game
+
+    questions =
+        GekanatorQuestion
+        .accepted
+        .includes(:gekanator_question_examples)
+        .where(kind: 'post_similarity', source: 'user_suggested')
+        .to_a
+
+    selected = weighted_sample_questions(
+        questions,
+        post_id: game.correct_post_id,
+        limit: 2)
+
+    render json: {
+      questions: selected.map { |question| extra_question_json(question) }
+    }
+  end
+
+  def extra_question_answers
+    return head :not_found unless current_user&.admin?
+
+    game = GekanatorGame.find_by(id: params[:id])
+    return head :not_found unless game
+
+    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 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
+end
@@ -0,0 +1,46 @@
+class GekanatorPostsController < ApplicationController
+  def index
+    return head :not_found unless current_user&.admin?
+
+    posts =
+        Post
+        .preload(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'))
+
+    render json: { posts: posts.map { |post| post_json(post) } }
+  end
+
+  private
+
+  def post_json post
+    {
+      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,
+      tags: post.tags.map { |tag| tag_json(tag) }
+    }
+  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
@@ -0,0 +1,53 @@
+class GekanatorQuestionSuggestionsController < ApplicationController
+  def create
+    return head :not_found unless current_user&.admin?
+
+    game = GekanatorGame.find_by(id: params.require(:gekanator_game_id))
+    return head :not_found unless game
+
+    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
+end
@@ -0,0 +1,100 @@
+class GekanatorQuestionsController < ApplicationController
+  def index
+    return head :not_found unless current_user&.admin?
+
+    questions =
+        GekanatorQuestion
+        .accepted
+        .includes(:gekanator_question_examples)
+        .order(priority_weight: :desc, id: :asc)
+
+    render json: {
+      questions: questions.map { |question| question_json(question) }
+    }
+  end
+
+  private
+
+  def question_json question
+    condition = condition_json(question.condition).deep_symbolize_keys
+    json = {
+      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'
+      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 '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?"
+    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
+end
@@ -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
@@ -0,0 +1,15 @@
+class GekanatorGame < ApplicationRecord
+  belongs_to :user
+  belongs_to :guessed_post, class_name: 'Post'
+  belongs_to :correct_post, class_name: 'Post'
+  has_many :question_suggestions,
+           class_name: 'GekanatorQuestionSuggestion',
+           dependent: :delete_all
+  has_many :question_examples,
+           class_name: 'GekanatorQuestionExample',
+           dependent: :delete_all
+
+  validates :answers, presence: true
+  validates :question_count, numericality: { greater_than_or_equal_to: 0 }
+  validates :won, inclusion: { in: [true, false] }
+end
@@ -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
@@ -0,0 +1,97 @@
+class GekanatorQuestionExample < ApplicationRecord
+  ANSWERS = GekanatorQuestionSuggestion::ANSWERS
+  NON_UNKNOWN_ANSWERS = ANSWERS - ['unknown']
+  SOURCES = ['initial_suggestion', '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 if new_record?
+
+    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
@@ -0,0 +1,25 @@
+class GekanatorQuestionSuggestion < ApplicationRecord
+  MAX_QUESTIONS_PER_GAME = 3
+  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] }
+  validate :question_suggestion_limit_per_game, on: :create
+
+  private
+
+  def question_suggestion_limit_per_game
+    return if gekanator_game_id.blank?
+
+    count = GekanatorQuestionSuggestion.where(gekanator_game_id:).count
+    if count >= MAX_QUESTIONS_PER_GAME
+      errors.add(:base, '質問追加数を超えてゐます．')
+    end
+  end
+end
@@ -11,6 +11,17 @@ class Post < ApplicationRecord
  has_many :user_post_views, dependent: :delete_all
  has_many :post_similarities, dependent: :delete_all
  has_many :post_versions
+  has_many :gekanator_guessed_games,
+           class_name: 'GekanatorGame',
+           foreign_key: :guessed_post_id,
+           dependent: :delete_all,
+           inverse_of: :guessed_post
+  has_many :gekanator_correct_games,
+           class_name: 'GekanatorGame',
+           foreign_key: :correct_post_id,
+           dependent: :delete_all,
+           inverse_of: :correct_post
+  has_many :gekanator_question_examples, dependent: :delete_all

  has_many :parent_post_implications,
           class_name: 'PostImplication',
@@ -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
@@ -0,0 +1,18 @@
+module Gekanator
+  class QuestionSuggestionAiConverter
+    def self.call(...) = new(...).call
+
+    def initialize suggestion:, user:
+      @suggestion = suggestion
+      @user = user
+    end
+
+    def call
+      raise NotImplementedError, 'AI question conversion is not implemented yet.'
+    end
+
+    private
+
+    attr_reader :suggestion, :user
+  end
+end
@@ -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
@@ -63,6 +63,24 @@ Rails.application.routes.draw do
    end
  end

+  namespace :gekanator do
+    resources :games, only: [:create], controller: '/gekanator_games' do
+      member do
+        get :extra_questions
+        post :extra_question_answers
+      end
+    end
+    resources :posts, only: [:index], controller: '/gekanator_posts'
+    resources :questions, only: [:index], controller: '/gekanator_questions'
+    resources :question_suggestions,
+              only: [:create],
+              controller: '/gekanator_question_suggestions' do
+      member do
+        post :ai_convert
+      end
+    end
+  end
+
  resources :users, only: [:create, :update] do
    collection do
      post :verify
@@ -0,0 +1,18 @@
+class CreateGekanatorGames < ActiveRecord::Migration[8.0]
+  def change
+    create_table :gekanator_games do |t|
+      t.references :user, null: false, foreign_key: true
+      t.references :guessed_post, null: false, foreign_key: { to_table: :posts }
+      t.references :correct_post, null: false, foreign_key: { to_table: :posts }
+      t.boolean :won, null: false
+      t.integer :question_count, null: false
+      t.json :answers, null: false
+
+      t.timestamps
+    end
+
+    add_check_constraint :gekanator_games,
+                         'question_count >= 0',
+                         name: 'chk_gekanator_games_question_count_nonnegative'
+  end
+end
@@ -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
@@ -0,0 +1,5 @@
+class AddAnswerToGekanatorQuestionSuggestions < ActiveRecord::Migration[8.0]
+  def change
+    add_column :gekanator_question_suggestions, :answer, :string, null: false
+  end
+end
@@ -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
@@ -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
@@ -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
@@ -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
@@ -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_06_000000) do
+ActiveRecord::Schema[8.0].define(version: 2026_06_12_000000) do
  create_table "active_storage_attachments", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
    t.string "name", null: false
    t.string "record_type", null: false
@@ -48,6 +48,79 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_06_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
+    t.bigint "correct_post_id", null: false
+    t.boolean "won", null: false
+    t.integer "question_count", null: false
+    t.json "answers", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["correct_post_id"], name: "index_gekanator_games_on_correct_post_id"
+    t.index ["guessed_post_id"], name: "index_gekanator_games_on_guessed_post_id"
+    t.index ["user_id"], name: "index_gekanator_games_on_user_id"
+    t.check_constraint "`question_count` >= 0", name: "chk_gekanator_games_question_count_nonnegative"
+  end
+
+  create_table "gekanator_question_examples", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "gekanator_question_id", null: false
+    t.bigint "post_id", null: false
+    t.bigint "user_id", null: false
+    t.bigint "gekanator_game_id"
+    t.string "answer", null: false
+    t.string "source", default: "post_game_extra", null: false
+    t.float "weight", default: 1.0, null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.json "answer_counts", null: false
+    t.integer "sample_count", default: 1, null: false
+    t.index ["gekanator_game_id"], name: "index_gekanator_question_examples_on_gekanator_game_id"
+    t.index ["gekanator_question_id", "post_id", "user_id"], name: "idx_gekanator_question_examples_on_question_post_user", unique: true
+    t.index ["gekanator_question_id"], name: "index_gekanator_question_examples_on_gekanator_question_id"
+    t.index ["post_id"], name: "index_gekanator_question_examples_on_post_id"
+    t.index ["user_id"], name: "index_gekanator_question_examples_on_user_id"
+  end
+
+  create_table "gekanator_question_suggestions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "gekanator_game_id", null: false
+    t.bigint "user_id", null: false
+    t.text "question_text", null: false
+    t.boolean "processed", default: false, null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.string "answer", null: false
+    t.index ["gekanator_game_id"], name: "index_gekanator_question_suggestions_on_gekanator_game_id"
+    t.index ["user_id"], name: "index_gekanator_question_suggestions_on_user_id"
+  end
+
+  create_table "gekanator_questions", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.string "text", null: false
+    t.string "kind", null: false
+    t.json "condition", null: false
+    t.string "source", default: "ai_generated", null: false
+    t.string "status", default: "pending", null: false
+    t.float "priority_weight", default: 1.0, null: false
+    t.bigint "gekanator_question_suggestion_id"
+    t.bigint "created_by_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["created_by_id"], name: "index_gekanator_questions_on_created_by_id"
+    t.index ["gekanator_question_suggestion_id"], name: "index_gekanator_questions_on_gekanator_question_suggestion_id"
+  end
+
  create_table "ip_addresses", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
    t.binary "ip_address", limit: 16, null: false
    t.datetime "banned_at"
@@ -478,6 +551,18 @@ ActiveRecord::Schema[8.0].define(version: 2026_06_06_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"
@@ -0,0 +1,75 @@
+require 'rails_helper'
+
+RSpec.describe 'Gekanator games API', type: :request do
+  let!(:admin) { create_admin_user! }
+  let!(:user) { create_member_user! }
+  let!(:guessed_post) { Post.create!(title: 'guess', url: 'https://example.com/guess') }
+  let!(:correct_post) { Post.create!(title: 'correct', url: 'https://example.com/correct') }
+
+  describe 'POST /gekanator/games' do
+    it 'stores a won game' do
+      sign_in_as admin
+
+      post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          correct_post_id: guessed_post.id,
+          answers: [{ question_id: 'tag:1', answer: 'yes' }] }
+
+      expect(response).to have_http_status(:created)
+      game = GekanatorGame.find(json['id'])
+      expect(game.user).to eq(admin)
+      expect(game.guessed_post).to eq(guessed_post)
+      expect(game.correct_post).to eq(guessed_post)
+      expect(game.won).to eq(true)
+      expect(game.question_count).to eq(1)
+      expect(game.answers).to eq([{ 'question_id' => 'tag:1', 'answer' => 'yes' }])
+    end
+
+    it 'stores a lost game with the correct post' do
+      sign_in_as admin
+
+      post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          correct_post_id: correct_post.id,
+          question_count: 4,
+          answers: [{ question_id: 'tag:1', answer: 'no' }] }
+
+      expect(response).to have_http_status(:created)
+      game = GekanatorGame.find(json['id'])
+      expect(game.correct_post).to eq(correct_post)
+      expect(game.won).to eq(false)
+      expect(game.question_count).to eq(1)
+    end
+
+    it 'rejects a game without the correct post' do
+      sign_in_as admin
+
+      post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          question_count: 4,
+          answers: [{ question_id: 'tag:1', answer: 'no' }] }
+
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+
+    it 'returns not found without an admin 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)
+    end
+
+    it 'returns not found for a non-admin user' do
+      sign_in_as user
+
+      post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          correct_post_id: guessed_post.id,
+          answers: [{ question_id: 'tag:1', answer: 'yes' }] }
+
+      expect(response).to have_http_status(:not_found)
+    end
+  end
+end
@@ -0,0 +1,612 @@
+require 'rails_helper'
+
+RSpec.describe 'Gekanator learning API', type: :request do
+  let(:admin) { create(:user, :admin) }
+  let(:member) { create(:user, :member) }
+  let(:other_user) { create(:user, :member) }
+
+  let!(:guessed_post) do
+    Post.create!(
+      title: 'guessed',
+      url: 'https://example.com/guessed'
+    )
+  end
+
+  let!(:correct_post) do
+    Post.create!(
+      title: 'correct',
+      url: 'https://example.com/correct'
+    )
+  end
+
+  let!(:other_post) do
+    Post.create!(
+      title: 'other',
+      url: 'https://example.com/other'
+    )
+  end
+
+  let!(:game) do
+    GekanatorGame.create!(
+      user: admin,
+      guessed_post: guessed_post,
+      correct_post: correct_post,
+      won: false,
+      question_count: 1,
+      answers: [
+        {
+          'question_id' => 'tag:character:喜多郁代',
+          'question_text' => '喜多ちゃんが関係してる?',
+          'answer' => 'yes',
+          'original_answer' => 'yes'
+        }
+      ]
+    )
+  end
+
+  def create_post_similarity_question!(
+    text: '喜多ちゃんが泣いてる?',
+    post: correct_post,
+    answer: 'yes',
+    status: 'accepted',
+    source: 'user_suggested',
+    priority_weight: 1.2
+  )
+    GekanatorQuestion.create!(
+      text: text,
+      kind: 'post_similarity',
+      source: source,
+      status: status,
+      priority_weight: priority_weight,
+      condition: {
+        type: 'post-similarity',
+        postId: post.id,
+        answer: answer,
+        threshold: 0.65
+      },
+      created_by: admin
+    )
+  end
+
+  describe 'POST /gekanator/games' do
+    it 'stores a game result for an admin user' do
+      sign_in_as admin
+
+      post '/gekanator/games', params: {
+        guessed_post_id: guessed_post.id,
+        correct_post_id: correct_post.id,
+        answers: [
+          {
+            question_id: 'tag:character:喜多郁代',
+            question_text: '喜多ちゃんが関係してる?',
+            answer: 'yes',
+            original_answer: 'yes'
+          }
+        ]
+      }
+
+      expect(response).to have_http_status(:created)
+
+      created = GekanatorGame.find(json['id'])
+      expect(created.user).to eq(admin)
+      expect(created.guessed_post).to eq(guessed_post)
+      expect(created.correct_post).to eq(correct_post)
+      expect(created.won).to eq(false)
+      expect(created.question_count).to eq(1)
+      expect(created.answers).to eq([
+        {
+          'question_id' => 'tag:character:喜多郁代',
+          'question_text' => '喜多ちゃんが関係してる?',
+          'answer' => 'yes',
+          'original_answer' => 'yes'
+        }
+      ])
+    end
+
+    it 'stores a won game when guessed_post_id equals correct_post_id' do
+      sign_in_as admin
+
+      post '/gekanator/games', params: {
+        guessed_post_id: correct_post.id,
+        correct_post_id: correct_post.id,
+        answers: []
+      }
+
+      expect(response).to have_http_status(:created)
+      expect(GekanatorGame.find(json['id']).won).to eq(true)
+    end
+
+    it 'rejects a game without correct_post_id' do
+      sign_in_as admin
+
+      expect {
+        post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          answers: []
+        }
+      }.not_to change { GekanatorGame.count }
+
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+
+    it 'returns not found for a non-admin user' do
+      sign_in_as member
+
+      post '/gekanator/games', params: {
+        guessed_post_id: guessed_post.id,
+        correct_post_id: correct_post.id,
+        answers: []
+      }
+
+      expect(response).to have_http_status(:not_found)
+    end
+  end
+
+  describe 'POST /gekanator/question_suggestions' do
+    it 'creates a suggestion and promotes yes answer to an accepted post_similarity question' do
+      sign_in_as admin
+
+      expect {
+        post '/gekanator/question_suggestions', params: {
+          gekanator_game_id: game.id,
+          question_text: '喜多ちゃんが泣いてる?',
+          answer: 'yes'
+        }
+      }.to change { GekanatorQuestionSuggestion.count }.by(1)
+        .and change { GekanatorQuestion.count }.by(1)
+        .and change { GekanatorQuestionExample.count }.by(1)
+
+      expect(response).to have_http_status(:created)
+
+      suggestion = GekanatorQuestionSuggestion.last
+      question = GekanatorQuestion.last
+      example = GekanatorQuestionExample.last
+
+      expect(json).to include(
+        'id' => suggestion.id,
+        'count' => 1
+      )
+
+      expect(suggestion).to have_attributes(
+        gekanator_game_id: game.id,
+        user_id: admin.id,
+        question_text: '喜多ちゃんが泣いてる?',
+        answer: 'yes',
+        processed: true
+      )
+
+      expect(question).to have_attributes(
+        text: '喜多ちゃんが泣いてる?',
+        kind: 'post_similarity',
+        source: 'user_suggested',
+        status: 'accepted',
+        priority_weight: 1.2,
+        gekanator_question_suggestion_id: suggestion.id,
+        created_by_id: admin.id
+      )
+      expect(question.condition).to include(
+        'type' => 'post-similarity',
+        'postId' => correct_post.id,
+        'answer' => 'yes',
+        'threshold' => 0.65
+      )
+
+      expect(example).to have_attributes(
+        gekanator_question_id: question.id,
+        post_id: correct_post.id,
+        user_id: admin.id,
+        gekanator_game_id: game.id,
+        answer: 'yes',
+        source: 'initial_suggestion',
+        weight: 1.0
+      )
+    end
+
+    it 'promotes no, partial, and probably_no answers' do
+      sign_in_as admin
+
+      ['no', 'partial', 'probably_no'].each do |answer|
+        expect {
+          post '/gekanator/question_suggestions', params: {
+            gekanator_game_id: game.id,
+            question_text: "answer #{answer} question?",
+            answer: answer
+          }
+        }.to change { GekanatorQuestion.count }.by(1)
+          .and change { GekanatorQuestionExample.count }.by(1)
+
+        expect(response).to have_http_status(:created)
+        expect(GekanatorQuestion.last.condition['answer']).to eq(answer)
+        expect(GekanatorQuestionExample.last.answer).to eq(answer)
+      end
+    end
+
+    it 'does not promote unknown answers' do
+      sign_in_as admin
+
+      expect {
+        post '/gekanator/question_suggestions', params: {
+          gekanator_game_id: game.id,
+          question_text: 'よく分からない質問?',
+          answer: 'unknown'
+        }
+      }.to change { GekanatorQuestionSuggestion.count }.by(1)
+        .and change { GekanatorQuestion.count }.by(0)
+        .and change { GekanatorQuestionExample.count }.by(0)
+
+      expect(response).to have_http_status(:created)
+      expect(GekanatorQuestionSuggestion.last.processed).to eq(false)
+    end
+
+    it 'limits suggestions to three per game' do
+      sign_in_as admin
+
+      3.times do |i|
+        GekanatorQuestionSuggestion.create!(
+          gekanator_game: game,
+          user: admin,
+          question_text: "existing question #{i}",
+          answer: 'unknown'
+        )
+      end
+
+      expect {
+        post '/gekanator/question_suggestions', params: {
+          gekanator_game_id: game.id,
+          question_text: 'fourth question?',
+          answer: 'yes'
+        }
+      }.not_to change { GekanatorQuestionSuggestion.count }
+
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+
+    it 'returns not found for a non-admin user' do
+      sign_in_as member
+
+      post '/gekanator/question_suggestions', params: {
+        gekanator_game_id: game.id,
+        question_text: 'member question?',
+        answer: 'yes'
+      }
+
+      expect(response).to have_http_status(:not_found)
+    end
+  end
+
+  describe 'GET /gekanator/games/:id/extra_questions' do
+    it 'returns at most two accepted user_suggested post_similarity questions without duplicates' do
+      sign_in_as admin
+
+      low = create_post_similarity_question!(
+        text: 'low?',
+        priority_weight: 1.0
+      )
+      high = create_post_similarity_question!(
+        text: 'high?',
+        priority_weight: 3.0
+      )
+      middle = create_post_similarity_question!(
+        text: 'middle?',
+        priority_weight: 2.0
+      )
+
+      get "/gekanator/games/#{game.id}/extra_questions"
+
+      expect(response).to have_http_status(:ok)
+      expect(json['questions'].length).to eq(2)
+      expect(json['questions'].map { _1['id'] }.uniq.length).to eq(2)
+      expect(json['questions'].map { _1['id'] }).to all(be_in([low.id, high.id, middle.id]))
+    end
+
+    it 'can return questions that already have an example for the correct post' do
+      sign_in_as admin
+
+      existing = create_post_similarity_question!(text: 'already learned?')
+
+      GekanatorQuestionExample.create!(
+        gekanator_question: existing,
+        post: correct_post,
+        user: admin,
+        gekanator_game: game,
+        answer: 'yes',
+        source: 'post_game_extra'
+      )
+
+      get "/gekanator/games/#{game.id}/extra_questions"
+
+      expect(response).to have_http_status(:ok)
+      expect(json['questions'].map { _1['id'] }).to include(existing.id)
+    end
+
+    it 'can return questions already asked in the game using snake_case question_id' do
+      sign_in_as admin
+
+      asked = create_post_similarity_question!(text: 'already asked?')
+      game.update!(
+        answers: [
+          {
+            'question_id' => "post-similarity:#{asked.id}",
+            'answer' => 'yes'
+          }
+        ]
+      )
+
+      get "/gekanator/games/#{game.id}/extra_questions"
+
+      expect(response).to have_http_status(:ok)
+      expect(json['questions'].map { _1['id'] }).to include(asked.id)
+    end
+
+    it 'can return questions already asked in the game using camelCase questionId' do
+      sign_in_as admin
+
+      asked = create_post_similarity_question!(text: 'already asked?')
+      game.update!(
+        answers: [
+          {
+            'questionId' => "post-similarity:#{asked.id}",
+            'answer' => 'yes'
+          }
+        ]
+      )
+
+      get "/gekanator/games/#{game.id}/extra_questions"
+
+      expect(response).to have_http_status(:ok)
+      expect(json['questions'].map { _1['id'] }).to include(asked.id)
+    end
+
+    it 'does not return non-accepted, non-user_suggested, or non-post_similarity questions' do
+      sign_in_as admin
+
+      accepted = create_post_similarity_question!(text: 'accepted?')
+      create_post_similarity_question!(text: 'disabled?', status: 'disabled')
+      create_post_similarity_question!(text: 'ai?', source: 'ai_generated')
+      GekanatorQuestion.create!(
+        text: 'tag?',
+        kind: 'tag',
+        source: 'user_suggested',
+        status: 'accepted',
+        priority_weight: 1.0,
+        condition: { type: 'tag', key: 'character:喜多郁代' }
+      )
+
+      get "/gekanator/games/#{game.id}/extra_questions"
+
+      expect(response).to have_http_status(:ok)
+      expect(json['questions'].map { _1['id'] }).to contain_exactly(accepted.id)
+    end
+  end
+
+  describe 'POST /gekanator/games/:id/extra_question_answers' do
+    it 'creates examples for extra question answers' do
+      sign_in_as admin
+
+      question = create_post_similarity_question!(text: 'extra?')
+
+      expect {
+        post "/gekanator/games/#{game.id}/extra_question_answers", params: {
+          answers: [
+            {
+              question_id: question.id.to_s,
+              answer: 'partial'
+            }
+          ]
+        }
+      }.to change { GekanatorQuestionExample.count }.by(1)
+
+      expect(response).to have_http_status(:created)
+      expect(json).to include('count' => 1)
+
+      example = GekanatorQuestionExample.last
+      expect(example).to have_attributes(
+        gekanator_question_id: question.id,
+        post_id: correct_post.id,
+        user_id: admin.id,
+        gekanator_game_id: game.id,
+        answer: 'partial',
+        source: 'post_game_extra',
+        weight: 1.0
+      )
+    end
+
+    it 'updates an existing example for the same question, post, and user' do
+      sign_in_as admin
+
+      question = create_post_similarity_question!(text: 'extra?')
+      existing = GekanatorQuestionExample.create!(
+        gekanator_question: question,
+        post: correct_post,
+        user: admin,
+        answer: 'no',
+        source: 'post_game_extra',
+        weight: 1.0
+      )
+
+      expect {
+        post "/gekanator/games/#{game.id}/extra_question_answers", params: {
+          answers: [
+            {
+              question_id: question.id,
+              answer: 'yes'
+            }
+          ]
+        }
+      }.not_to change { GekanatorQuestionExample.count }
+
+      expect(response).to have_http_status(:created)
+      expect(existing.reload).to have_attributes(
+        answer: 'yes',
+        source: 'post_game_extra',
+        gekanator_game_id: game.id
+      )
+    end
+
+    it 'rejects missing questions' do
+      sign_in_as admin
+
+      expect {
+        post "/gekanator/games/#{game.id}/extra_question_answers", params: {
+          answers: [
+            {
+              question_id: 999_999_999,
+              answer: 'yes'
+            }
+          ]
+        }
+      }.not_to change { GekanatorQuestionExample.count }
+
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+
+    it 'rejects non-accepted questions' do
+      sign_in_as admin
+
+      question = create_post_similarity_question!(
+        text: 'disabled?',
+        status: 'disabled'
+      )
+
+      post "/gekanator/games/#{game.id}/extra_question_answers", params: {
+        answers: [
+          {
+            question_id: question.id,
+            answer: 'yes'
+          }
+        ]
+      }
+
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+
+    it 'rejects non-post_similarity questions' do
+      sign_in_as admin
+
+      question = GekanatorQuestion.create!(
+        text: 'tag?',
+        kind: 'tag',
+        source: 'user_suggested',
+        status: 'accepted',
+        priority_weight: 1.0,
+        condition: { type: 'tag', key: 'character:喜多郁代' }
+      )
+
+      post "/gekanator/games/#{game.id}/extra_question_answers", params: {
+        answers: [
+          {
+            question_id: question.id,
+            answer: 'yes'
+          }
+        ]
+      }
+
+      expect(response).to have_http_status(:unprocessable_entity)
+    end
+  end
+
+  describe 'GET /gekanator/questions' do
+    it 'returns accepted questions only and includes example_answers for post_similarity questions' do
+      sign_in_as admin
+
+      accepted = create_post_similarity_question!(text: 'accepted?')
+      create_post_similarity_question!(
+        text: 'disabled?',
+        status: 'disabled'
+      )
+
+      GekanatorQuestionExample.create!(
+        gekanator_question: accepted,
+        post: correct_post,
+        user: admin,
+        answer: 'yes',
+        source: 'initial_suggestion',
+        weight: 1.0
+      )
+
+      get '/gekanator/questions'
+
+      expect(response).to have_http_status(:ok)
+      expect(json['questions'].length).to eq(1)
+
+      question_json = json['questions'].first
+      expect(question_json).to include(
+        'id' => "post-similarity:#{accepted.id}",
+        'text' => 'accepted?',
+        'kind' => 'post_similarity',
+        'source' => 'user_suggested',
+        'priority_weight' => 1.2
+      )
+      expect(question_json['condition']).to include(
+        'type' => 'post-similarity',
+        'postId' => correct_post.id,
+        'answer' => 'yes',
+        'threshold' => 0.65
+      )
+      expect(question_json['example_answers']).to include(
+        correct_post.id.to_s => 'yes'
+      )
+    end
+
+    it 'aggregates example_answers by weight' do
+      sign_in_as admin
+
+      question = create_post_similarity_question!(text: 'weighted?')
+
+      GekanatorQuestionExample.create!(
+        gekanator_question: question,
+        post: other_post,
+        user: admin,
+        answer: 'yes',
+        source: 'post_game_extra',
+        weight: 1.0
+      )
+      GekanatorQuestionExample.create!(
+        gekanator_question: question,
+        post: other_post,
+        user: other_user,
+        answer: 'no',
+        source: 'post_game_extra',
+        weight: 2.0
+      )
+
+      get '/gekanator/questions'
+
+      expect(response).to have_http_status(:ok)
+      question_json = json['questions'].find { _1['id'] == "post-similarity:#{question.id}" }
+      expect(question_json['example_answers']).to include(
+        other_post.id.to_s => 'no'
+      )
+    end
+
+    it 'normalizes legacy title length questions' do
+      sign_in_as admin
+
+      GekanatorQuestion.create!(
+        text: '題名が長めの投稿?',
+        kind: 'title',
+        source: 'admin_curated',
+        status: 'accepted',
+        priority_weight: 1.0,
+        condition: {
+          type: 'title-length-greater-than',
+          length: 20
+        },
+        created_by: admin
+      )
+
+      get '/gekanator/questions'
+
+      expect(response).to have_http_status(:ok)
+      question_json = json['questions'].find { _1['id'] == 'title:length-at-least:21' }
+      expect(question_json).to include(
+        'text' => 'タイトルは 21 文字以上?',
+        'kind' => 'title'
+      )
+      expect(question_json['condition']).to include(
+        'type' => 'title-length-at-least',
+        'length' => 21
+      )
+    end
+  end
+end
@@ -33,6 +33,10 @@ npm run lint

 If either command cannot be run or fails, report the exact command and failure.

+Do not create, modify, or run tests unless the user explicitly asks for test
+work. When the user asks for tests, keep working and rerun them until they
+pass or the remaining failure is clearly blocked.
+
 ## TypeScript

 - TypeScript is strict. `tsconfig.app.json` enables `strict`,
@@ -18,6 +18,7 @@ import MaterialListPage from '@/pages/materials/MaterialListPage'
 import MaterialNewPage from '@/pages/materials/MaterialNewPage'
 // import MaterialSearchPage from '@/pages/materials/MaterialSearchPage'
 import MorePage from '@/pages/MorePage'
+import GekanatorPage from '@/pages/GekanatorPage'
 import NicoTagListPage from '@/pages/tags/NicoTagListPage'
 import NotFound from '@/pages/NotFound'
 import TOSPage from '@/pages/TOSPage.mdx'
@@ -39,7 +40,7 @@ import WikiHistoryPage from '@/pages/wiki/WikiHistoryPage'
 import WikiNewPage from '@/pages/wiki/WikiNewPage'
 import WikiSearchPage from '@/pages/wiki/WikiSearchPage'

-import type { Dispatch, FC, SetStateAction } from 'react'
+import type { Dispatch, FC, ReactNode, SetStateAction } from 'react'

 import type { User } from '@/types'

@@ -80,6 +81,10 @@ 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="/more" element={<MorePage/>}/>
 	  <Route path="*" element={<NotFound/>}/>
 	</Routes>
@@ -87,6 +92,16 @@ 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
@@ -0,0 +1,375 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+import { apiPost } from '@/lib/api'
+import {
+  buildGekanatorQuestions,
+  expectedAnswerForQuestion,
+  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 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('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',
+              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')
+  })
+})
+
+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(false)
+  })
+
+  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)
+  })
+})
+
+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\?$/)
+    expect(titleQuestion?.id).toMatch(/^title:length-at-least:\d+$/)
+  })
+})
+
+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',
+        },
+        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',
+          },
+          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',
+          },
+        ],
+      },
+    )
+  })
+})
@@ -0,0 +1,564 @@
+import { apiGet, apiPost } from '@/lib/api'
+
+import type { Post } from '@/types'
+
+export type GekanatorAnswerValue =
+    | 'yes'
+    | 'no'
+    | 'partial'
+    | 'probably_no'
+    | 'unknown'
+
+export type GekanatorAnswerLog = {
+    questionId:       string
+    questionText:     string
+    questionCondition?:  GekanatorQuestionCondition
+    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 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: '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 = {
+    id:              string
+    text:            string
+    kind:            GekanatorQuestionKind
+    condition:       GekanatorQuestionCondition
+    source?:         GekanatorQuestionSource
+    priorityWeight?: number
+    exampleAnswers?: Record<`${ number }`, GekanatorAnswerValue> }
+
+export type GekanatorQuestion = {
+    id:              string
+    text:            string
+    kind:            GekanatorQuestionKind
+    condition:       GekanatorQuestionCondition
+    source:          GekanatorQuestionSource
+    priorityWeight:  number
+    exampleAnswers?: Record<`${ number }`, GekanatorAnswerValue>
+    test:            (post: Post) => boolean }
+
+
+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'
+  }
+}
+
+
+const directExampleAnswerFor = (
+    question:  StoredGekanatorQuestion,
+    post:      Post,
+): GekanatorAnswerValue | null => {
+  if (question.kind !== 'post_similarity')
+    return null
+
+  const direct = question.exampleAnswers?.[String (post.id) as `${ number }`]
+  if (direct)
+    return direct
+
+  if (question.condition.type === 'post-similarity' && question.condition.postId === post.id)
+    return question.condition.answer
+
+  return null
+}
+
+const countBy = <T extends string | number> (values: T[]): Map<T, number> => {
+  const counts = new Map<T, number> ()
+  values.forEach (value => counts.set (value, (counts.get (value) ?? 0) + 1))
+  return counts
+}
+
+
+const median = (values: number[]): number => {
+  const sorted = [...values].sort ((a, b) => a - b)
+  return sorted[Math.floor (sorted.length / 2)] ?? 0
+}
+
+
+const hostOf = (post: Post): string | null => {
+  try
+  {
+    return new URL (post.url).hostname.replace (/^www\./, '')
+  }
+  catch
+  {
+    return null
+  }
+}
+
+
+const originalYearOf = (post: Post): number | null => {
+  const value = post.originalCreatedFrom || post.originalCreatedBefore
+  if (!(value))
+    return null
+
+  const date = new Date (value)
+  if (Number.isNaN (date.getTime ()))
+    return null
+
+  return date.getFullYear ()
+}
+
+
+const originalDateOf = (post: Post): Date | null => {
+  const value = post.originalCreatedFrom || post.originalCreatedBefore
+  if (!(value))
+    return null
+
+  const date = new Date (value)
+  if (Number.isNaN (date.getTime ()))
+    return null
+
+  return date
+}
+
+
+const originalMonthOf = (post: Post): number | null => {
+  const date = originalDateOf (post)
+  if (!(date))
+    return null
+
+  return date.getMonth () + 1
+}
+
+
+const originalMonthDayOf = (post: Post): string | null => {
+  const date = originalDateOf (post)
+  if (!(date))
+    return null
+
+  return `${ date.getMonth () + 1 }-${ date.getDate () }`
+}
+
+
+const tagQuestionKey = ({ category, name }: { category: string; name: string }): string =>
+    `${ category }:${ name }`
+
+
+const tagFromQuestionKey = (key: string): { category: string; name: string } => {
+  const [category, ...rest] = key.split (':')
+  return { category: category ?? '', name: rest.join (':') }
+}
+
+
+const nicoTagLabel = (name: string): string => name.replace (/^nico:/, '')
+
+
+const tagQuestionText = (category: string, label: string): string => {
+  switch (category)
+  {
+  case 'deerjikist':
+    return `作者・ニジラーとして「${ 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)
+
+  return (
+    post.tags.some (tag =>
+	tag.name === name
+	&& tag.category === category
+	&& !(tag.category === 'meta')
+	&& !(tag.name.includes ('タグ希望'))
+	&& !(tag.name.includes ('bot操作'))))
+}
+
+
+const questionMatches = (
+    post:       Post,
+    question:   StoredGekanatorQuestion,
+): boolean => {
+  const directAnswer = directExampleAnswerFor (question, post)
+  if (directAnswer)
+    return question.condition.type === 'post-similarity'
+	? directAnswer === question.condition.answer
+	: directAnswer === 'yes'
+
+  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 'post-similarity':
+    return false
+  }
+}
+
+
+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 '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':
+    return questionMatches (post, question) ? 'yes' : 'no'
+  case 'post-similarity':
+    return null
+  }
+}
+
+
+export const restoreGekanatorQuestion = (
+    question:  StoredGekanatorQuestion,
+): GekanatorQuestion => {
+  const normalizedCondition = normalizeTitleLengthCondition (question.condition)
+  const normalizedQuestion = {
+      ...question,
+      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:${ question.condition.length + 1 }`
+      : question.id,
+  text: question.text,
+  kind: question.kind,
+  condition: normalizeTitleLengthCondition (question.condition),
+  source: question.source,
+  priorityWeight: question.priorityWeight,
+  exampleAnswers: question.exampleAnswers })
+
+
+export const fetchGekanatorPosts = async (): Promise<Post[]> => {
+  const data = await apiGet<{ posts: Post[] }> ('/gekanator/posts')
+  return data.posts
+}
+
+
+export const fetchGekanatorQuestions = async (): Promise<StoredGekanatorQuestion[]> => {
+  const data = await apiGet<{ questions: StoredGekanatorQuestion[] }> ('/gekanator/questions')
+  return data.questions
+}
+
+
+export const fetchGekanatorExtraQuestions = async (
+    gameId:  number,
+    nonce?: string,
+): Promise<GekanatorExtraQuestion[]> => {
+  const data = await apiGet<{ questions: GekanatorExtraQuestion[] }> (
+      `/gekanator/games/${ gameId }/extra_questions`,
+      { params: nonce ? { nonce } : undefined })
+  return data.questions
+}
+
+
+export const buildGekanatorQuestions = (posts: Post[]): GekanatorQuestion[] => {
+  const tagCounts = countBy (posts.flatMap (post =>
+      post.tags
+      .filter (tag =>
+	  !(tag.category === 'meta')
+	  && !(tag.name.includes ('タグ希望'))
+	  && !(tag.name.includes ('bot操作')))
+      .map (tag => tagQuestionKey (tag))))
+  const hosts = countBy (posts.map (hostOf).filter ((host): host is string => Boolean (host)))
+  const originalYears = countBy (
+      posts
+      .map (originalYearOf)
+      .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 usefulEntries = <T extends string | number> (counts: Map<T, 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)
+
+  const tagQuestions = usefulEntries (tagCounts)
+      .filter (([, count]) => count >= 2 && count <= Math.max (2, posts.length * .7))
+      .slice (0, 80)
+      .map (([key]) => {
+	const { category, name } = tagFromQuestionKey (String (key))
+	const label = category === 'nico' ? nicoTagLabel (name) : name
+
+	return {
+	    id:   `tag:${ key }`,
+	    text: tagQuestionText (category, label),
+	    kind: 'tag' as const,
+	    condition: { type: 'tag' as const, key: String (key) },
+	    source: 'default' as const,
+	    priorityWeight: 1,
+	    test: (post: Post) => questionableTag (post, String (key)) }
+      })
+
+  const sourceQuestions = usefulEntries (hosts)
+      .filter (([, count]) => count >= 2 && count <= Math.max (2, posts.length * .7))
+      .slice (0, 20)
+      .map (([host]) => ({
+	  id:   `source:${ host }`,
+	  text: `${ host } の投稿を思ひ浮かべてゐる?`,
+	  kind: 'source' as const,
+	  condition: { type: 'source' as const, host },
+	  source: 'default' as const,
+	  priorityWeight: 1,
+	  test: (post: Post) => hostOf (post) === host }))
+
+  const originalYearQuestions = usefulEntries (originalYears)
+      .filter (([, count]) => count >= 2 && count <= Math.max (2, posts.length * .7))
+      .slice (0, 20)
+      .map (([year]) => ({
+	  id:   `original-year:${ year }`,
+	  text: `オリジナルの投稿年は ${ year } 年?`,
+	  kind: 'original_date' as const,
+	  condition: { type: 'original-year' as const, year },
+	  source: 'default' as const,
+	  priorityWeight: 1,
+	  test: (post: Post) => originalYearOf (post) === year }))
+
+  const originalMonthQuestions = usefulEntries (originalMonths)
+      .filter (([, count]) => count >= 2 && count <= Math.max (2, posts.length * .7))
+      .slice (0, 20)
+      .map (([month]) => ({
+	  id:   `original-month:${ month }`,
+	  text: `オリジナルの投稿月は ${ month } 月?`,
+	  kind: 'original_date' as const,
+	  condition: { type: 'original-month' as const, month },
+	  source: 'default' as const,
+	  priorityWeight: 1,
+	  test: (post: Post) => originalMonthOf (post) === month }))
+
+  const originalMonthDayQuestions = usefulEntries (originalMonthDays)
+      .filter (([, count]) => count >= 2 && count <= Math.max (2, posts.length * .7))
+      .slice (0, 20)
+      .map (([monthDay]) => {
+	const [month, day] = String (monthDay).split ('-')
+
+	return {
+	    id:   `original-month-day:${ monthDay }`,
+	    text: `オリジナルの投稿日は ${ month } 月 ${ day } 日?`,
+	    kind: 'original_date' as const,
+	    condition: { type: 'original-month-day' as const, monthDay: String (monthDay) },
+	    source: 'default' as const,
+	    priorityWeight: 1,
+	    test: (post: Post) => originalMonthDayOf (post) === monthDay }
+      })
+
+  const titleQuestions = [
+      {
+	  id:   `title:length-at-least:${ titleLengthMedian }`,
+	  text: `タイトルは ${ titleLengthMedian } 文字以上?`,
+	  kind: 'title' as const,
+	  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
+      })
+
+  return [
+      ...sourceQuestions,
+      ...originalYearQuestions,
+      ...originalMonthQuestions,
+      ...originalMonthDayQuestions,
+      ...titleQuestions,
+      ...tagQuestions]
+}
+
+
+export const saveGekanatorGame = async ({
+    guessedPostId,
+    correctPostId,
+    answers,
+}: {
+    guessedPostId:  number
+    correctPostId:  number
+    answers:        GekanatorAnswerLog[]
+}): Promise<{ id: 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,
+	    question_condition: answer.questionCondition ?? null,
+	    answer: answer.answer,
+	    original_answer: answer.originalAnswer })) })
+
+
+export const saveGekanatorQuestionSuggestion = async ({
+    gekanatorGameId,
+    questionText,
+    answer,
+}: {
+    gekanatorGameId:  number
+    questionText:     string
+    answer:           GekanatorAnswerValue
+}): Promise<{ id: number; count: number }> =>
+    await apiPost ('/gekanator/question_suggestions', {
+	gekanator_game_id: gekanatorGameId,
+	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 })) })
@@ -0,0 +1,151 @@
+import { describe, expect, it } from 'vitest'
+
+import {
+    candidatePostsFor,
+    hardFilteredPostsForAnswer,
+    recoverCandidatePosts,
+} from '@/lib/gekanatorCandidateRecovery'
+
+import type {
+    GekanatorAnswerLog,
+    GekanatorAnswerValue,
+    GekanatorQuestion,
+} from '@/lib/gekanator'
+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 answer = (
+    question:  GekanatorQuestion,
+    value:     GekanatorAnswerValue,
+): GekanatorAnswerLog => ({
+  questionId: question.id,
+  questionText: question.text,
+  questionCondition: question.condition,
+  answer: value,
+  originalAnswer: value,
+})
+
+
+describe('candidatePostsFor', () => {
+  it('lets recovered candidates ignore old answers but not later 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, 1],
+	    [3, 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, 1]]) })
+
+    expect(candidates.map (candidate => candidate.id)).toEqual ([2])
+  })
+})
+
+
+describe('hardFilteredPostsForAnswer', () => {
+  it('returns zero candidates without falling back to the original pool', () => {
+    const posts = [post (1), post (2)]
+    const question = postSimilarityQuestion ('question', {
+	1: 'yes',
+	2: 'yes',
+    })
+
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'no',
+    })).toEqual ([])
+  })
+})
+
+
+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, 1]]),
+	eligiblePostIds: new Set ([9]),
+	answerCountAtRecovery: 2,
+	recoveryStepCount: 0,
+    })
+
+    expect(recovered?.recoveryStepCount).toBe (1)
+    expect([...(recovered?.recoveredCandidatePosts.keys () ?? [])])
+      .toEqual ([8, 7, 6, 5, 4, 3, 2])
+    expect(recovered?.recoveredCandidatePosts.get (7)).toBe (2)
+  })
+})
@@ -0,0 +1,146 @@
+import { expectedAnswerForQuestion } from '@/lib/gekanator'
+
+import type {
+    GekanatorAnswerLog,
+    GekanatorAnswerValue,
+    GekanatorQuestion,
+} from '@/lib/gekanator'
+import type { Post } from '@/types'
+
+
+export type RecoveredCandidatePost = {
+    postId:                number
+    answerCountAtRecovery: number }
+
+
+export const candidatePostsFor = ({
+    posts,
+    questions,
+    answers,
+    softenedQuestionIds,
+    rejectedPostIds,
+    recoveredCandidatePosts,
+}: {
+    posts:                   Post[]
+    questions:               GekanatorQuestion[]
+    answers:                 GekanatorAnswerLog[]
+    softenedQuestionIds:     Set<string>
+    rejectedPostIds:         Set<number>
+    recoveredCandidatePosts: Map<number, number>
+}): Post[] => {
+  const questionById = new Map (questions.map (question => [question.id, question]))
+
+  return posts.filter (post => {
+    if (rejectedPostIds.has (post.id))
+      return false
+
+    const answerCountAtRecovery = recoveredCandidatePosts.get (post.id)
+
+    return answers.every ((answer, index) => {
+      if (answerCountAtRecovery !== undefined && index < answerCountAtRecovery)
+	return true
+
+      if (softenedQuestionIds.has (answer.questionId))
+	return true
+
+      const question = questionById.get (answer.questionId)
+      if (!(question))
+	return true
+
+      switch (answer.answer)
+      {
+      case 'yes':
+      case 'no': {
+	const expected = expectedAnswerForQuestion (question, post)
+	return expected === null || expected === 'unknown' || expected === answer.answer
+      }
+      default:
+	return true
+      }
+    })
+  })
+}
+
+
+export const hardFilteredPostsForAnswer = ({
+    posts,
+    question,
+    answer,
+}: {
+    posts:     Post[]
+    question:  GekanatorQuestion
+    answer:    GekanatorAnswerValue
+}): Post[] => {
+  if (answer === 'unknown')
+    return posts
+
+  return posts.filter (post => {
+    const expected = expectedAnswerForQuestion (question, post)
+    return expected === null || expected === 'unknown' || expected === answer
+  })
+}
+
+
+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 nextRecoveryBatchSize = (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, number>
+    eligiblePostIds:         Set<number>
+    answerCountAtRecovery:   number
+    recoveryStepCount:       number
+}): {
+    recoveredCandidatePosts: Map<number, number>
+    recoveryStepCount:       number
+} | null => {
+  const recovered = new Map (recoveredCandidatePosts)
+  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, nextRecoveryBatchSize (recoveryStepCount))
+
+  if (candidates.length === 0)
+    return null
+
+  candidates.forEach (post => recovered.set (post.id, answerCountAtRecovery))
+
+  return {
+      recoveredCandidatePosts: recovered,
+      recoveryStepCount: recoveryStepCount + 1 }
+}
@@ -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)
+})
@@ -8,6 +8,13 @@ export const postsKeys = {
    changes:  (p: { post?: string; tag?: string; page: number; limit: number }) =>
 		  ['posts', 'changes', p] as const }

+export const gekanatorKeys = {
+    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,
    index:        (p: FetchTagsParams) => ['tags', 'index', p] as const,
@@ -0,0 +1,154 @@
+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)])
+
+
+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)
+  })
+})
作成者	SHA1	メッセージ	日付
みてるぞ	e94720941c	グカネータ作成 / ウィニング・ラン修正 (#41 ) (#366 ) Reviewed-on: #366 Co-authored-by: miteruzo <miteruzo@naver.com> Co-committed-by: miteruzo <miteruzo@naver.com>	2026-06-12 02:08:59 +09:00
みてるぞ	def6870f06	グカネータ / 質問パターン見直し (#41 ) (#365 ) Reviewed-on: #365 Co-authored-by: miteruzo <miteruzo@naver.com> Co-committed-by: miteruzo <miteruzo@naver.com>	2026-06-12 01:35:31 +09:00
みてるぞ	c361c561c2	グカネータ作成 / 質問パターン修正 (#41 ) (#364 ) Reviewed-on: #364 Co-authored-by: miteruzo <miteruzo@naver.com> Co-committed-by: miteruzo <miteruzo@naver.com>	2026-06-11 23:21:44 +09:00
みてるぞ	979ccf598e	グカネータ作成 / テスト型バグ修正 (#41 ) (#363 ) Reviewed-on: #363 Co-authored-by: miteruzo <miteruzo@naver.com> Co-committed-by: miteruzo <miteruzo@naver.com>	2026-06-10 23:43:50 +09:00
みてるぞ	37ade2a988	グカネータ作成 (#041 ) (#362 ) Reviewed-on: #362 Co-authored-by: miteruzo <miteruzo@naver.com> Co-committed-by: miteruzo <miteruzo@naver.com>	2026-06-10 23:33:56 +09:00
みてるぞ	7d48a8f694	上映会ニコニコ・バグ修正 (#358 ) (#359 ) Reviewed-on: #359 Co-authored-by: miteruzo <miteruzo@naver.com> Co-committed-by: miteruzo <miteruzo@naver.com>	2026-06-07 09:08:41 +09:00