グカネータ改良 (#371) (#375)

Reviewed-on: #375
Co-authored-by: miteruzo <miteruzo@naver.com>
Co-committed-by: miteruzo <miteruzo@naver.com>

AGENTS.md

@@ -125,6 +125,64 @@ npm run preview
 - TypeScript and TSX use 4-space logical indentation.
 - In TypeScript and TSX only, replace every leading run of 8 spaces with a tab.
 - Tabs are only for leading indentation, never for spaces after non-space text.
+- TypeScript and TSX imports may stay on one line if they remain within the
+  line limit; do not expand short type-only imports mechanically.
+- In TypeScript and TSX, when a function takes one destructured object
+  argument plus an inline type, prefer this shape when it fits locally:
+
+```ts
+const helper = (
+    { value, flag }: { value: string
+		       flag:  boolean },
+): Result => {
+  // ...
+}
+```
+
+- In TypeScript and TSX, put `switch` case block braces on their own lines
+  when a case needs a lexical block:
+
+```ts
+case 'yes':
+case 'no':
+  {
+    const expected = valueFor (item)
+    return expected == null || expected === answer
+  }
+```
+
+- In TypeScript and TSX, use `value == null` and `value != null` as the
+  default nullish checks. Do not use `=== null`, `=== undefined`,
+  `!== null`, or `!== undefined`.
+- If code appears to need a distinction between `null` and `undefined`, treat
+  that as a design smell and revise the logic to avoid the distinction.
+  External library APIs that explicitly require distinguishing the two are the
+  only exception.
+- In TypeScript and TSX, keep short arrays on one line when they fit under the
+  line limit; break arrays only when readability or line length requires it.
+- In TypeScript and TSX, when a ternary expression is split across multiple
+  lines, align `?` and `:` with the condition expression. Do not indent `?` and
+  `:` one extra level under the condition.
+
+```ts
+const value =
+    condition
+    ? consequent
+    : alternate
+```
+
+- In TypeScript and TSX, keep short ternary expressions on one line when they
+  fit cleanly under the line limit.
+- In TypeScript and TSX, prefer ternary expressions for simple conditional
+  value selection. Do not replace a clear ternary with `if` statements, and do
+  not introduce immediately invoked functions just to avoid or reformat a
+  ternary expression.
+- In TypeScript and TSX, do not write `let` followed by later `if` assignments
+  when the value can be expressed as a single `const` initializer. Prefer
+  `const` because it prevents accidental later reassignment.
+- When fixing formatting, change formatting only. Do not change expression
+  structure, control flow, or variable mutability unless the requested style
+  explicitly requires it.
 - Do not add production dependencies without explicit approval.
 - Do not create, modify, or run tests unless the user explicitly asks for
   test work. When the user asks for tests, keep working and rerun them until

backend/app/controllers/gekanator_games_controller.rb

@@ -14,11 +14,24 @@ class GekanatorGamesController < ApplicationController
         question_count: answers.length,
         answers:)
 
-    if game.save
-      render json: { id: game.id }, status: :created
-    else
+    if game.invalid?
       render json: { errors: game.errors.full_messages }, status: :unprocessable_entity
+      return
     end
+
+    learned_example_count = 0
+
+    ActiveRecord::Base.transaction do
+      game.save!
+      learned_example_count = learn_answers_from_game!(game)
+    end
+
+    render json: {
+      id: game.id,
+      learned_example_count:
+    }, status: :created
+  rescue ActiveRecord::RecordInvalid => e
+    render json: { errors: e.record.errors.full_messages }, status: :unprocessable_entity
   end
 
   def extra_questions
@@ -32,10 +45,12 @@ class GekanatorGamesController < ApplicationController
         .where(kind: 'post_similarity', source: 'user_suggested')
         .to_a
 
-    selected = weighted_sample_questions(
-        questions,
-        post_id: game.correct_post_id,
-        limit: 2)
+    selected =
+        prioritized_extra_questions(
+            questions,
+            post_id: game.correct_post_id,
+            user: current_user,
+            limit: 2)
 
     render json: {
       questions: selected.map { |question| extra_question_json(question) }
@@ -96,6 +111,23 @@ class GekanatorGamesController < ApplicationController
     }
   end
 
+  def prioritized_extra_questions questions, post_id:, user:, limit:
+    answered_question_ids =
+        GekanatorQuestionExample
+        .where(user:, gekanator_question_id: questions.map(&:id))
+        .distinct
+        .pluck(:gekanator_question_id)
+    unanswered, answered =
+        questions.partition { |question| !answered_question_ids.include?(question.id) }
+    selected = weighted_sample_questions(unanswered, post_id:, limit:)
+    return selected if selected.length >= limit
+
+    selected + weighted_sample_questions(
+        answered.reject { |question| selected.any? { _1.id == question.id } },
+        post_id:,
+        limit: limit - selected.length)
+  end
+
   def weighted_sample_questions questions, post_id:, limit:
     remaining = questions.uniq(&:id)
     selected = []
@@ -145,4 +177,96 @@ class GekanatorGamesController < ApplicationController
 
     game
   end
+
+  def learn_answers_from_game! game
+    correct_post = game.correct_post
+    return 0 if correct_post.blank?
+
+    accepted_questions =
+        GekanatorQuestion
+        .accepted
+        .index_by { |question| public_question_id_for(question) }
+    learned_count = 0
+
+    Array(game.answers).each do |answer|
+      answer_value = answer['answer'].to_s
+      next if answer_value.blank? || answer_value == 'unknown'
+
+      question_id = game_answer_question_id(answer)
+      next if question_id.blank?
+
+      question = accepted_questions[question_id.to_s]
+      next unless learnable_game_answer_question?(question)
+
+      example =
+          GekanatorQuestionExample.find_or_initialize_by(
+              gekanator_question: question,
+              post: correct_post,
+              user: current_user)
+      example.record_answer!(
+          answer: answer_value,
+          source: 'post_game_answer',
+          gekanator_game: game)
+      example.save!
+      learned_count += 1
+    end
+
+    learned_count
+  end
+
+  def public_question_id_for question
+    condition = normalize_condition(question.condition)
+
+    case condition[:type]
+    when 'tag'
+      "tag:#{condition[:key]}"
+    when 'source'
+      "source:#{condition[:host]}"
+    when 'original-year'
+      "original-year:#{condition[:year]}"
+    when 'original-month'
+      "original-month:#{condition[:month]}"
+    when 'original-month-day'
+      "original-month-day:#{condition[:monthDay] || condition[:month_day]}"
+    when 'title-length-at-least'
+      "title:length-at-least:#{condition[:length]}"
+    when 'title-length-greater-than'
+      "title:length-at-least:#{condition[:length].to_i + 1}"
+    when 'title-has-ascii'
+      'title:ascii'
+    when 'title-contains'
+      "title:contains:#{condition[:text]}"
+    when 'post-similarity'
+      "post-similarity:#{question.id}"
+    else
+      "catalog:#{question.id}"
+    end
+  end
+
+  def normalize_condition condition
+    json = condition.deep_dup.as_json
+
+    if json['type'] == 'original-month-day' && json['monthDay'].blank?
+      json['monthDay'] = json.delete('month_day')
+    end
+
+    json.deep_symbolize_keys
+  end
+
+  def learnable_game_answer_question? question
+    return false if question.nil?
+    return true if question.kind == 'post_similarity'
+    return false unless question.kind == 'tag'
+
+    condition = normalize_condition(question.condition)
+    key = condition[:key].to_s
+    !key.start_with?('nico:')
+  end
+
+  def game_answer_question_id answer
+    answer['question_id'] ||
+      answer[:question_id] ||
+      answer['questionId'] ||
+      answer[:questionId]
+  end
 end

backend/app/controllers/gekanator_posts_controller.rb

@@ -2,7 +2,7 @@ class GekanatorPostsController < ApplicationController
   def index
     posts =
         Post
-        .preload(tags: :tag_name)
+        .preload(:post_similarities, tags: :tag_name)
         .with_attached_thumbnail
         .order(Arel.sql(
             'COALESCE(posts.original_created_before - INTERVAL 1 MINUTE, ' \
@@ -22,6 +22,12 @@ class GekanatorPostsController < ApplicationController
       thumbnail_base: post.thumbnail_base,
       original_created_from: post.original_created_from,
       original_created_before: post.original_created_before,
+      post_similarity_edges: post.post_similarities.map { |similarity|
+        {
+          target_post_id: similarity.target_post_id,
+          cos: similarity.cos.to_f
+        }
+      },
       tags: post.tags.map { |tag| tag_json(tag) }
     }
   end

backend/app/controllers/gekanator_question_suggestions_controller.rb

@@ -8,6 +8,35 @@ class GekanatorQuestionSuggestionsController < ApplicationController
       return head :not_found
     end
 
+    existing_question_id = params[:existing_question_id].presence
+    if existing_question_id
+      question = GekanatorQuestion.accepted.find_by(id: existing_question_id)
+      return head :not_found unless question
+      unless learnable_existing_question?(question)
+        return render_validation_error fields: { existing_question_id: ['質問が不正です．'] }
+      end
+
+      example =
+          GekanatorQuestionExample.find_or_initialize_by(
+              gekanator_question: question,
+              post: game.correct_post,
+              user: current_user)
+      example.record_answer!(
+          answer: params.require(:answer),
+          source: 'post_game_extra',
+          gekanator_game: game)
+
+      if example.save
+        render json: {
+          id: question.id,
+          count: game.question_suggestions.count
+        }, status: :created
+      else
+        render_validation_error example
+      end
+      return
+    end
+
     suggestion = GekanatorQuestionSuggestion.new(
         gekanator_game: game,
         user: current_user,
@@ -53,4 +82,14 @@ class GekanatorQuestionSuggestionsController < ApplicationController
   rescue NotImplementedError
     head :not_implemented
   end
+
+  private
+
+  def learnable_existing_question? question
+    return true if question.kind == 'post_similarity'
+    return false unless question.kind == 'tag'
+
+    key = question.condition.as_json['key'].to_s
+    !key.start_with?('nico:')
+  end
 end

backend/app/controllers/gekanator_questions_controller.rb

@@ -16,6 +16,7 @@ class GekanatorQuestionsController < ApplicationController
   def question_json question
     condition = condition_json(question.condition).deep_symbolize_keys
     json = {
+      record_id: question.id,
       id: question_id_for(question, condition),
       text: question_text_for(question, condition),
       kind: question.kind,
@@ -23,7 +24,7 @@ class GekanatorQuestionsController < ApplicationController
       source: question.source,
       priority_weight: question.priority_weight
     }
-    if question.kind == 'post_similarity'
+    if question.kind == 'post_similarity' || question.kind == 'tag'
       json[:example_answers] = example_answers_json(question)
     end
     json

backend/app/models/gekanator_question_example.rb

@@ -1,7 +1,7 @@
 class GekanatorQuestionExample < ApplicationRecord
   ANSWERS = GekanatorQuestionSuggestion::ANSWERS
   NON_UNKNOWN_ANSWERS = ANSWERS - ['unknown']
-  SOURCES = ['initial_suggestion', 'post_game_extra'].freeze
+  SOURCES = ['initial_suggestion', 'post_game_answer', 'post_game_extra'].freeze
 
   belongs_to :gekanator_question
   belongs_to :post
@@ -35,7 +35,7 @@ class GekanatorQuestionExample < ApplicationRecord
     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?
+    self.source = source
 
     apply_aggregated_answer!(preferred_answer: answer)
     self

backend/app/models/gekanator_question_suggestion.rb

@@ -1,5 +1,4 @@
 class GekanatorQuestionSuggestion < ApplicationRecord
-  MAX_QUESTIONS_PER_GAME = 3
   ANSWERS = ['yes', 'no', 'partial', 'probably_no', 'unknown'].freeze
 
   belongs_to :gekanator_game
@@ -10,16 +9,4 @@ class GekanatorQuestionSuggestion < ApplicationRecord
   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

backend/spec/requests/gekanator_learning_spec.rb

@@ -151,6 +151,154 @@ RSpec.describe 'Gekanator learning API', type: :request do
 
       expect(response).to have_http_status(:unauthorized)
     end
+
+    it 'learns accepted non-nico tag answers from camelCase main game logs' do
+      sign_in_as admin
+
+      tag_question = GekanatorQuestion.create!(
+        text: 'MAD 要素がある?',
+        kind: 'tag',
+        source: 'admin_curated',
+        status: 'accepted',
+        priority_weight: 1.0,
+        condition: { type: 'tag', key: 'meme:MAD' },
+        created_by: admin
+      )
+
+      expect {
+        post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          correct_post_id: correct_post.id,
+          answers: [
+            {
+              questionId: 'tag:meme:MAD',
+              question_text: 'MAD 要素がある?',
+              answer: 'yes',
+              original_answer: 'yes'
+            },
+            {
+              questionId: 'tag:meme:missing',
+              question_text: '存在しない質問?',
+              answer: 'yes',
+              original_answer: 'yes'
+            },
+            {
+              questionId: 'tag:meme:MAD',
+              question_text: 'MAD 要素がある?',
+              answer: 'unknown',
+              original_answer: 'unknown'
+            }
+          ]
+        }
+      }.to change { GekanatorQuestionExample.count }.by(1)
+
+      expect(response).to have_http_status(:created)
+      expect(json['learned_example_count']).to eq(1)
+
+      example = GekanatorQuestionExample.last
+      expect(example).to have_attributes(
+        gekanator_question_id: tag_question.id,
+        post_id: correct_post.id,
+        user_id: admin.id,
+        answer: 'yes',
+        source: 'post_game_answer'
+      )
+      expect(example.gekanator_game_id).to eq(json['id'])
+    end
+
+    it 'does not learn fact questions or nico tag questions from main game logs' do
+      sign_in_as admin
+
+      [
+        {
+          text: 'example.com 由来?',
+          kind: 'source',
+          condition: { type: 'source', host: 'example.com' }
+        },
+        {
+          text: '題名に結束バンドを含む?',
+          kind: 'title',
+          condition: { type: 'title-contains', text: '結束バンド' }
+        },
+        {
+          text: '2024 年投稿?',
+          kind: 'original_date',
+          condition: { type: 'original-year', year: 2024 }
+        },
+        {
+          text: 'ニコニコにぼっちタグ?',
+          kind: 'tag',
+          condition: { type: 'tag', key: 'nico:ぼっち' }
+        }
+      ].each do |attributes|
+        GekanatorQuestion.create!(
+          text: attributes[:text],
+          kind: attributes[:kind],
+          source: 'admin_curated',
+          status: 'accepted',
+          priority_weight: 1.0,
+          condition: attributes[:condition],
+          created_by: admin
+        )
+      end
+
+      expect {
+        post '/gekanator/games', params: {
+          guessed_post_id: guessed_post.id,
+          correct_post_id: correct_post.id,
+          answers: [
+            { question_id: 'source:example.com', answer: 'yes' },
+            { question_id: 'title:contains:結束バンド', answer: 'yes' },
+            { question_id: 'original-year:2024', answer: 'yes' },
+            { question_id: 'tag:nico:ぼっち', answer: 'yes' }
+          ]
+        }
+      }.not_to change { GekanatorQuestionExample.count }
+
+      expect(response).to have_http_status(:created)
+      expect(json['learned_example_count']).to eq(0)
+    end
+
+    it 'updates an existing main game example instead of duplicating it' do
+      sign_in_as admin
+
+      tag_question = GekanatorQuestion.create!(
+        text: '喜多ちゃんが関係してる?',
+        kind: 'tag',
+        source: 'admin_curated',
+        status: 'accepted',
+        priority_weight: 1.0,
+        condition: { type: 'tag', key: 'character:喜多郁代' },
+        created_by: admin
+      )
+      existing = GekanatorQuestionExample.create!(
+        gekanator_question: tag_question,
+        post: correct_post,
+        user: admin,
+        answer: 'no',
+        source: 'post_game_answer',
+        weight: 1.0
+      )
+
+      expect {
+        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',
+              answer: 'yes',
+              original_answer: 'yes'
+            }
+          ]
+        }
+      }.not_to change { GekanatorQuestionExample.count }
+
+      expect(response).to have_http_status(:created)
+      expect(json['learned_example_count']).to eq(1)
+      expect(existing.reload.answer).to eq('yes')
+      expect(existing.sample_count).to eq(2)
+    end
   end
 
   describe 'POST /gekanator/question_suggestions' do
@@ -249,7 +397,7 @@ RSpec.describe 'Gekanator learning API', type: :request do
       expect(GekanatorQuestionSuggestion.last.processed).to eq(false)
     end
 
-    it 'limits suggestions to three per game' do
+    it 'allows more than three suggestions per game' do
       sign_in_as admin
 
       3.times do |i|
@@ -267,9 +415,10 @@ RSpec.describe 'Gekanator learning API', type: :request do
           question_text: 'fourth question?',
           answer: 'yes'
         }
-      }.not_to change { GekanatorQuestionSuggestion.count }
+      }.to change { GekanatorQuestionSuggestion.count }.by(1)
 
-      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response).to have_http_status(:created)
+      expect(json['count']).to eq(4)
     end
 
     it 'allows a non-admin user to suggest a question for their own game' do

frontend/src/lib/gekanator.ts

@@ -62,6 +62,7 @@ export type GekanatorExtraQuestion = {
     priorityWeight:  number }
 
 export type StoredGekanatorQuestion = {
+    recordId?:       number
     id:              string
     text:            string
     kind:            GekanatorQuestionKind
@@ -71,6 +72,7 @@ export type StoredGekanatorQuestion = {
     exampleAnswers?: Record<`${ number }`, GekanatorAnswerValue> }
 
 export type GekanatorQuestion = {
+    recordId?:       number
     id:              string
     text:            string
     kind:            GekanatorQuestionKind
@@ -148,7 +150,7 @@ const directExampleAnswerFor = (
     question:  StoredGekanatorQuestion,
     post:      Post,
 ): GekanatorAnswerValue | null => {
-  if (question.kind !== 'post_similarity')
+  if (question.kind !== 'post_similarity' && question.kind !== 'tag')
     return null
 
   const direct = question.exampleAnswers?.[String (post.id) as `${ number }`]
@@ -348,6 +350,7 @@ export const restoreGekanatorQuestion = (
   const normalizedCondition = normalizeTitleLengthCondition (question.condition)
   const normalizedQuestion = {
       ...question,
+      recordId: question.recordId,
       id: normalizedCondition.type === 'title-length-at-least'
 	  ? `title:length-at-least:${ normalizedCondition.length }`
 	  : question.id,
@@ -367,6 +370,7 @@ export const storeGekanatorQuestion = (
   id: question.condition.type === 'title-length-greater-than'
       ? `title:length-at-least:${ question.condition.length + 1 }`
       : question.id,
+  recordId: question.recordId,
   text: question.text,
   kind: question.kind,
   condition: normalizeTitleLengthCondition (question.condition),
@@ -581,7 +585,7 @@ export const saveGekanatorGame = async ({
     guessedPostId:  number
     correctPostId:  number
     answers:        GekanatorAnswerLog[]
-}): Promise<{ id: number }> =>
+}): Promise<{ id: number; learnedExampleCount: number }> =>
     await apiPost ('/gekanator/games', {
 	guessed_post_id: guessedPostId,
 	correct_post_id: correctPostId,
@@ -595,15 +599,18 @@ export const saveGekanatorGame = async ({
 
 export const saveGekanatorQuestionSuggestion = async ({
     gekanatorGameId,
+    existingQuestionId,
     questionText,
     answer,
 }: {
     gekanatorGameId:  number
-    questionText:     string
+    existingQuestionId?: number
+    questionText?:    string
     answer:           GekanatorAnswerValue
 }): Promise<{ id: number; count: number }> =>
     await apiPost ('/gekanator/question_suggestions', {
 	gekanator_game_id: gekanatorGameId,
+	existing_question_id: existingQuestionId,
 	question_text: questionText,
 	answer })
 

frontend/src/lib/gekanatorCandidateRecovery.test.ts

@@ -51,6 +51,21 @@ const postSimilarityQuestion = (
 })
 
 
+const sourceQuestion = (
+    host:  string,
+): GekanatorQuestion => ({
+  id: `source:${ host }`,
+  text: `${ host }?`,
+  kind: 'source',
+  condition: {
+      type: 'source',
+      host },
+  source: 'default',
+  priorityWeight: 1,
+  test: candidate => new URL (candidate.url).hostname === host,
+})
+
+
 const answer = (
     question:  GekanatorQuestion,
     value:     GekanatorAnswerValue,
@@ -64,7 +79,7 @@ const answer = (
 
 
 describe('candidatePostsFor', () => {
-  it('lets recovered candidates ignore old answers but not later answers', () => {
+  it('does not hard-filter semantic post_similarity answers', () => {
     const posts = [post (1), post (2), post (3)]
     const oldQuestion = postSimilarityQuestion ('old', {
 	1: 'no',
@@ -77,6 +92,29 @@ describe('candidatePostsFor', () => {
 	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 ([1, 2, 3])
+  })
+
+  it('lets recovered candidates ignore old fact answers but not later fact answers', () => {
+    const posts = [
+	{ ...post (1), url: 'https://other.example/posts/1' },
+	post (2),
+	{ ...post (3), url: 'https://example.com/posts/3' },
+    ]
+    const oldQuestion = sourceQuestion ('old.example.com')
+    const laterQuestion = sourceQuestion ('example.com')
+
     const candidates = candidatePostsFor ({
 	posts,
 	questions: [oldQuestion, laterQuestion],
@@ -112,7 +150,7 @@ describe('candidatePostsFor', () => {
 
 
 describe('hardFilteredPostsForAnswer', () => {
-  it('returns zero candidates without falling back to the original pool', () => {
+  it('keeps the original pool for semantic post_similarity answers', () => {
     const posts = [post (1), post (2)]
     const question = postSimilarityQuestion ('question', {
 	1: 'yes',
@@ -123,7 +161,41 @@ describe('hardFilteredPostsForAnswer', () => {
 	posts,
 	question,
 	answer: 'no',
-    })).toEqual ([])
+    })).toEqual (posts)
+  })
+
+  it('hard-filters fact answers only for yes and no', () => {
+    const posts = [
+	{ ...post (1), url: 'https://example.com/posts/1' },
+	{ ...post (2), url: 'https://other.example/posts/2' },
+    ]
+    const question = sourceQuestion ('example.com')
+
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'yes',
+    }).map (candidate => candidate.id)).toEqual ([1])
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'no',
+    }).map (candidate => candidate.id)).toEqual ([2])
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'partial',
+    })).toEqual (posts)
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'probably_no',
+    })).toEqual (posts)
+    expect(hardFilteredPostsForAnswer ({
+	posts,
+	question,
+	answer: 'unknown',
+    })).toEqual (posts)
   })
 })
 

frontend/src/lib/gekanatorCandidateRecovery.ts

@@ -1,33 +1,33 @@
 import { expectedAnswerForQuestion } from '@/lib/gekanator'
 
-import type {
-    GekanatorAnswerLog,
-    GekanatorAnswerValue,
-    GekanatorQuestion,
-} 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 questionIsFactLikeForHardFiltering = (question:  GekanatorQuestion): boolean =>
+    !(question.kind === 'post_similarity'
+      || (question.kind === 'tag'
+	  && question.condition.type === 'tag'
+	  && !(question.condition.key.startsWith ('nico:'))))
+
+
+export const candidatePostsFor = (
+    { posts,
+      questions,
+      answers,
+      softenedQuestionIds,
+      rejectedPostIds,
+      recoveredCandidatePosts }: { posts:                   Post[]
+				   questions:               GekanatorQuestion[]
+				   answers:                 GekanatorAnswerLog[]
+				   softenedQuestionIds:     Set<string>
+				   rejectedPostIds:         Set<number>
+				   recoveredCandidatePosts: Map<number, number> },
+): Post[] => {
   const questionById = new Map (questions.map (question => [question.id, question]))
 
   return posts.filter (post => {
@@ -37,7 +37,7 @@ export const candidatePostsFor = ({
     const answerCountAtRecovery = recoveredCandidatePosts.get (post.id)
 
     return answers.every ((answer, index) => {
-      if (answerCountAtRecovery !== undefined && index < answerCountAtRecovery)
+      if (answerCountAtRecovery != null && index < answerCountAtRecovery)
 	return true
 
       if (softenedQuestionIds.has (answer.questionId))
@@ -46,14 +46,17 @@ export const candidatePostsFor = ({
       const question = questionById.get (answer.questionId)
       if (!(question))
 	return true
+      if (!(questionIsFactLikeForHardFiltering (question)))
+	return true
 
       switch (answer.answer)
       {
       case 'yes':
-      case 'no': {
-	const expected = expectedAnswerForQuestion (question, post)
-	return expected === null || expected === 'unknown' || expected === answer.answer
-      }
+      case 'no':
+	{
+	  const expected = expectedAnswerForQuestion (question, post)
+	  return expected === null || expected === 'unknown' || expected === answer.answer
+	}
       default:
 	return true
       }
@@ -62,30 +65,25 @@ export const candidatePostsFor = ({
 }
 
 
-export const hardFilteredPostsForAnswer = ({
-    posts,
-    question,
-    answer,
-}: {
-    posts:     Post[]
-    question:  GekanatorQuestion
-    answer:    GekanatorAnswerValue
-}): Post[] => {
-  if (answer === 'unknown')
+export const hardFilteredPostsForAnswer = (
+    { posts, question, answer }: { posts:     Post[]
+				   question:  GekanatorQuestion
+				   answer:    GekanatorAnswerValue },
+): Post[] => {
+  if (!(questionIsFactLikeForHardFiltering (question)))
+    return posts
+
+  if (!(answer === 'yes' || answer === 'no'))
     return posts
 
   return posts.filter (post => {
     const expected = expectedAnswerForQuestion (question, post)
-    return expected === null || expected === 'unknown' || expected === answer
+    return expected == null || expected === 'unknown' || expected === answer
   })
 }
 
 
-const concreteAnswerOptions: GekanatorAnswerValue[] = [
-    'yes',
-    'no',
-    'partial',
-    'probably_no']
+const concreteAnswerOptions: GekanatorAnswerValue[] = ['yes', 'no', 'partial', 'probably_no']
 
 
 export const allConcreteAnswerOptionsExhausted = (
@@ -104,45 +102,39 @@ const nextRecoveryTargetSize = (recoveryStepCount: number): number =>
     6 * (2 ** recoveryStepCount)
 
 
-export const recoverCandidatePosts = ({
-    posts,
-    scores,
-    rejectedPostIds,
-    recoveredCandidatePosts,
-    eligiblePostIds,
-    answerCountAtRecovery,
-    recoveryStepCount,
-}: {
-    posts:                   Post[]
-    scores:                  Map<number, number>
-    rejectedPostIds:         Set<number>
-    recoveredCandidatePosts: Map<number, number>
-    eligiblePostIds:         Set<number>
-    answerCountAtRecovery:   number
-    recoveryStepCount:       number
-}): {
-    recoveredCandidatePosts: Map<number, number>
-    recoveryStepCount:       number
-} | null => {
+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 targetSize = nextRecoveryTargetSize (recoveryStepCount)
-  const countedPostIds = new Set ([
-      ...eligiblePostIds,
-      ...recovered.keys ()])
+  const countedPostIds = new Set ([...eligiblePostIds, ...recovered.keys ()])
   const addCount = targetSize - countedPostIds.size
   if (addCount <= 0)
-    return {
-	recoveredCandidatePosts: recovered,
-	recoveryStepCount: recoveryStepCount + 1 }
+    {
+      return { recoveredCandidatePosts: recovered,
+	       recoveryStepCount: recoveryStepCount + 1 }
+    }
 
-  const candidates = posts
-      .filter (post =>
-	  !(rejectedPostIds.has (post.id))
-	  && !(eligiblePostIds.has (post.id))
-	  && !(recovered.has (post.id)))
-      .sort ((a, b) =>
-	  (scores.get (b.id) ?? Number.NEGATIVE_INFINITY)
-	      - (scores.get (a.id) ?? Number.NEGATIVE_INFINITY))
+  const candidates =
+      posts
+      .filter (post => (!(rejectedPostIds.has (post.id))
+			&& !(eligiblePostIds.has (post.id))
+			&& !(recovered.has (post.id))))
+      .sort ((a, b) => ((scores.get (b.id) ?? Number.NEGATIVE_INFINITY)
+			- (scores.get (a.id) ?? Number.NEGATIVE_INFINITY)))
       .slice (0, addCount)
 
   if (candidates.length === 0)
@@ -150,7 +142,6 @@ export const recoverCandidatePosts = ({
 
   candidates.forEach (post => recovered.set (post.id, answerCountAtRecovery))
 
-  return {
-      recoveredCandidatePosts: recovered,
-      recoveryStepCount: recoveryStepCount + 1 }
+  return { recoveredCandidatePosts: recovered,
+	   recoveryStepCount: recoveryStepCount + 1 }
 }

frontend/src/pages/GekanatorPage.test.tsx

@@ -1,3 +1,6 @@
+import { readFileSync } from 'node:fs'
+import { resolve } from 'node:path'
+
 import { describe, expect, it } from 'vitest'
 
 import { isQuestionHardFilteredAfterAnswers } from '@/lib/gekanatorQuestionFilters'
@@ -49,6 +52,57 @@ const blocked = (
     isQuestionHardFilteredAfterAnswers (question (candidate), [answer (previous, value)])
 
 
+const gekanatorPageSource = readFileSync (
+    resolve (process.cwd (), 'src/pages/GekanatorPage.tsx'),
+    'utf8')
+
+const gekanatorBackdropSource = gekanatorPageSource.slice (
+    gekanatorPageSource.indexOf ('const GekanatorBackdrop'),
+    gekanatorPageSource.indexOf ('const expectedAnswerFor'))
+
+
+describe('GekanatorBackdrop regression structure', () => {
+  it('keeps displayedBackdropMode as the render-time source of truth', () => {
+    expect(gekanatorBackdropSource).not.toContain ('isLeavingGuessBackdrop')
+    expect(gekanatorBackdropSource).not.toContain ('renderBackdropMode')
+    expect(gekanatorBackdropSource).not.toContain ('renderWinningRunCount')
+    expect(gekanatorBackdropSource).not.toContain ('renderThumbnails')
+    expect(gekanatorBackdropSource).not.toContain ('renderIsCrossfading')
+
+    expect(gekanatorBackdropSource).toContain (
+      "const renderedSettings = settingsForMode (displayedBackdropMode)")
+    expect(gekanatorBackdropSource).toContain (
+      'scaleForMode (displayedBackdropMode, displayedWinningRunCount)')
+    expect(gekanatorBackdropSource).toContain (
+      "backdropMode === 'guess' || displayedBackdropMode === 'guess'")
+  })
+
+  it('does not split guess into a separate renderer or force a remount', () => {
+    expect(gekanatorBackdropSource).not.toContain ('renderStaticGuessBackdrop')
+    expect(gekanatorBackdropSource).not.toContain ('guessZoomAnimationKey')
+    expect(gekanatorBackdropSource).not.toContain ('shouldAnimateGuessZoomIn')
+    expect(gekanatorBackdropSource).not.toContain ('previousBackdropModeRef')
+    expect(gekanatorBackdropSource).not.toContain (
+      'if (isGuessPresentation && guessThumbnail)')
+  })
+
+  it('keeps tile keys independent from backdrop mode', () => {
+    expect(gekanatorBackdropSource).toContain ('key={duplicate}')
+    expect(gekanatorBackdropSource).toContain ('key={`${ duplicate }:${ index }`}')
+    expect(gekanatorBackdropSource).not.toMatch (/key=\{`\$\{\s*mode/)
+    expect(gekanatorBackdropSource).not.toMatch (/key=\{`\$\{\s*displayedBackdropMode/)
+  })
+
+  it('keeps guess on the shared scale, x, and y animation path', () => {
+    expect(gekanatorBackdropSource).toContain ('animate={{ scale: renderedScale')
+    expect(gekanatorBackdropSource).toContain (
+      "x: displayedBackdropMode === 'guess' ? guessFocusOffset.x : '0%'")
+    expect(gekanatorBackdropSource).toContain (
+      "y: displayedBackdropMode === 'guess' ? guessFocusOffset.y : '0%'")
+  })
+})
+
+
 describe('isQuestionHardFilteredAfterAnswers', () => {
   it('blocks only contradictory or redundant month questions after a yes answer', () => {
     const previous: GekanatorQuestionCondition = { type: 'original-month', month: 12 }

frontend/src/types.ts

@@ -139,6 +139,10 @@ export type Post = {
     title:                  string | null
     thumbnail:              string | null
     thumbnailBase:          string | null
+    postSimilarityEdges?:   {
+			      targetPostId: number
+			      cos:          number
+			  }[]
     tags:                   Tag[]
     parentPosts?:           Post[]
     childPosts?:            Post[]