AGENTS.md

@@ -173,6 +173,16 @@ const value =
 
 - 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

frontend/src/pages/GekanatorPage.tsx

@@ -25,6 +25,7 @@ import { gekanatorKeys } from '@/lib/queryKeys'
 import { cn } from '@/lib/utils'
 
 import type { FC } from 'react'
+import type { Transition } from 'framer-motion'
 
 import type { GekanatorAnswerLog,
 	      GekanatorAnswerValue,
@@ -243,16 +244,23 @@ const normalizeStoredQuestionId = (
 
 const normalizeStoredGame = (game: StoredGekanatorGame): StoredGekanatorGame => ({
   ...game,
-  answers: game.answers.map (answer => ({
-      ...answer,
-      questionId: normalizeStoredQuestionId (answer.questionId,
-					     answer.questionCondition),
-      questionMode: ((answer.questionMode === 'winning_run' || answer.questionMode === 'normal')
-		     ? answer.questionMode
-		     : undefined),
-      questionCondition: (answer.questionCondition
-			  ? normalizeTitleLengthCondition (answer.questionCondition)
-			  : undefined) })),
+  answers: game.answers.map (answer => {
+    const questionMode =
+	answer.questionMode === 'winning_run' || answer.questionMode === 'normal'
+	? answer.questionMode
+	: undefined
+    const questionCondition =
+	answer.questionCondition
+	? normalizeTitleLengthCondition (answer.questionCondition)
+	: undefined
+
+    return {
+	...answer,
+	questionId: normalizeStoredQuestionId (answer.questionId,
+					       answer.questionCondition),
+	questionMode,
+	questionCondition }
+  }),
   askedIds: game.askedIds.map (questionId => normalizeStoredQuestionId (questionId)),
   softenedQuestionIds: (game.softenedQuestionIds
 			.map (questionId => normalizeStoredQuestionId (questionId))),
@@ -474,10 +482,12 @@ const questionCategoryPenalty = (
     repeatPenalty:  number,
 ): number => {
   const earlyFactor = Math.max (0, (3 - answerCount) / 3)
-  const titleLengthPenalty =
-      titleLengthMinimumForCondition (question.condition) == null
-      ? 0
-      : (answerCount === 0 ? 8 : 3.5) * earlyFactor
+  const titleLengthPenalty = (() => {
+    if (titleLengthMinimumForCondition (question.condition) == null)
+      return 0
+
+    return (answerCount === 0 ? 8 : 3.5) * earlyFactor
+  }) ()
 
   switch (question.kind)
   {
@@ -649,21 +659,21 @@ const buildMaterialIndex = (
     const originalValue = post.originalCreatedFrom || post.originalCreatedBefore
     const date =
 	originalValue
-	  ? new Date (originalValue)
-	  : null
+	? new Date (originalValue)
+	: null
     const validDate =
 	date && !(Number.isNaN (date.getTime ()))
-	  ? date
-	  : null
+	? date
+	: null
     const originalYear = validDate?.getFullYear () ?? null
     const originalMonth =
 	validDate
-	  ? validDate.getMonth () + 1
-	  : null
+	? validDate.getMonth () + 1
+	: null
     const originalMonthDay =
 	validDate
-	  ? `${ validDate.getMonth () + 1 }-${ validDate.getDate () }`
-	  : null
+	? `${ validDate.getMonth () + 1 }-${ validDate.getDate () }`
+	: null
     originalYearByPostId.set (post.id, originalYear)
     originalMonthByPostId.set (post.id, originalMonth)
     originalMonthDayByPostId.set (post.id, originalMonthDay)
@@ -758,10 +768,10 @@ const humanPriorityOffsetFor = (question: GekanatorQuestion): number => {
   case 'source':
     return -2.5
   case 'post_similarity':
-    return (
-      question.source === 'user_suggested' || question.source === 'admin_curated'
-	? -3.5
-	: -1.5)
+    if (question.source === 'user_suggested' || question.source === 'admin_curated')
+      return -3.5
+
+    return -1.5
   case 'original_date':
     switch (question.condition.type)
     {
@@ -1197,10 +1207,12 @@ const buildQuestionsForCandidateIds = (
 				     confirmationPostId?: number | null },
 ): GekanatorQuestion[] => {
   const total = candidateIds.length
-  const confirmationPost =
-      confirmationPostId == null
-	? null
-	: materialIndex.postById.get (confirmationPostId) ?? null
+  const confirmationPost = (() => {
+    if (confirmationPostId == null)
+      return null
+
+    return materialIndex.postById.get (confirmationPostId) ?? null
+  }) ()
 
   if (mode === 'split' && total === 0)
     return acceptedQuestions
@@ -1251,17 +1263,23 @@ const buildQuestionsForCandidateIds = (
 	  GekanatorQuestionCondition,
 	  { type: 'original-year' | 'original-month' | 'original-month-day' }
       >,
-  ): GekanatorQuestion => buildIndexedQuestion ({
+  ): GekanatorQuestion => {
+    const priorityWeight = (() => {
+      if (condition.type === 'original-year')
+	return 1.04
+      if (condition.type === 'original-month-day')
+	return 1.01
+
+      return .92
+    }) ()
+
+    return buildIndexedQuestion ({
       condition,
       text: originalDateQuestionTextFor (condition),
       kind: 'original_date',
-      priorityWeight:
-	  condition.type === 'original-year'
-	    ? 1.04
-	    : condition.type === 'original-month-day'
-	      ? 1.01
-	      : .92,
+      priorityWeight,
       materialIndex })
+  }
   const specialMonthDays = rankedEntriesForCounts ({
       counts: monthDayCounts,
       total,
@@ -1342,27 +1360,21 @@ const buildQuestionsForCandidateIds = (
       const titleLength = materialIndex.titleLengthByPostId.get (targetPostId) ?? 0
       const tagKeys = materialIndex.tagKeysByPostId.get (targetPostId) ?? []
 
-      addQuestion (
-	  host
-	    ? buildIndexedQuestion ({
-		condition: { type: 'source', host },
-		text: `${ host } の投稿を思い浮かべている?`,
-		kind: 'source',
-		priorityWeight: 1.02,
-		materialIndex })
-	    : null)
-      addQuestion (
-	  year != null && year != undefined
-	    ? buildDateQuestion ({
-		type: 'original-year',
-		year })
-	    : null)
-      addQuestion (
-	  monthDay && specialOriginalMonthDayLabelFor (monthDay)
-	    ? buildDateQuestion ({
-		type: 'original-month-day',
-		monthDay })
-	    : null)
+      if (host)
+	addQuestion (buildIndexedQuestion ({
+	    condition: { type: 'source', host },
+	    text: `${ host } の投稿を思い浮かべている?`,
+	    kind: 'source',
+	    priorityWeight: 1.02,
+	    materialIndex }))
+      if (year != null)
+	addQuestion (buildDateQuestion ({
+	    type: 'original-year',
+	    year }))
+      if (monthDay && specialOriginalMonthDayLabelFor (monthDay))
+	addQuestion (buildDateQuestion ({
+	    type: 'original-month-day',
+	    monthDay }))
 
       tagKeys
 	  .slice (0, 20)
@@ -1451,16 +1463,19 @@ const candidatePostsForState = ({
       if (!(condition))
 	return true
 
-      const matched = question
-	  ? matchingPostIdsForQuestion ({
+      const matched = (() => {
+	if (question)
+	  return matchingPostIdsForQuestion ({
 	      posts,
 	      materialIndex,
 	      matchIndex,
 	      question,
 	      dynamicMatchIndex })
-	  : matchingPostIdsForCondition ({
-	      condition,
-	      materialIndex })
+
+	return matchingPostIdsForCondition ({
+	    condition,
+	    materialIndex })
+      }) ()
       const useExpectedAnswer =
 	  question != null
 	  && usesLearnedTagExamples (question)
@@ -1477,9 +1492,7 @@ const candidatePostsForState = ({
 		  || expected === answer.answer
 	    }
 
-	  return answer.answer === 'yes'
-	      ? matched.has (post.id)
-	      : !(matched.has (post.id))
+	  return answer.answer === 'yes' ? matched.has (post.id) : !(matched.has (post.id))
 	}
 
       if (!(question))
@@ -1839,17 +1852,21 @@ const contradictionPenaltyFor = ({
     case 'partial':
       return sum + (isExclusiveContradiction (question.condition, previous) ? 25 : 0)
     case 'no':
-      return sum + (
+      if (
 	  sameConditionValue (question.condition, previous)
-	      || isMonthCrossMatch (question.condition, previous)
-	    ? 40
-	    : 0)
+	  || isMonthCrossMatch (question.condition, previous)
+      )
+	return sum + 40
+
+      return sum
     case 'probably_no':
-      return sum + (
+      if (
 	  sameConditionValue (question.condition, previous)
-	      || isMonthCrossMatch (question.condition, previous)
-	    ? 20
-	    : 0)
+	  || isMonthCrossMatch (question.condition, previous)
+      )
+	return sum + 20
+
+      return sum
     default:
       return sum
     }
@@ -2003,28 +2020,34 @@ const chooseQuestion = (
 	const humanOffset = humanPriorityOffsetFor (question)
 	const sourceBonus = sourcePriorityOffset (question)
 	const priorityBonus = priorityWeightOffset (question)
-	const repeatPenalty =
-	    answers.length === 0
-	      ? (recentFirstQuestionPenaltyById.get (question.id) ?? 0) * 4.5
-	      : 0
+	const repeatPenalty = (() => {
+	  if (answers.length === 0)
+	    return (recentFirstQuestionPenaltyById.get (question.id) ?? 0) * 4.5
+
+	  return 0
+	}) ()
 	const categoryPenalty = questionCategoryPenalty (
 	    question,
 	    answers.length,
 	    repeatPenalty)
-	const priorSplitScore =
-	    priorWeightTotal <= 0
-	      ? null
-	      : Math.abs (
-		    .5 - (
-		      priorEntries.reduce (
-			  (sum, [postId, weight]) => {
-			    return sum + (matched.has (postId) ? weight : 0)
-			  },
-			  0) / priorWeightTotal))
-	const priorBonus =
-	    priorSplitScore == null
-	      ? 0
-	      : Math.max (0, .22 - priorSplitScore) * -18
+	const priorSplitScore = (() => {
+	  if (priorWeightTotal <= 0)
+	    return null
+
+	  return Math.abs (
+	      .5 - (
+		priorEntries.reduce (
+		    (sum, [postId, weight]) => {
+		      return sum + (matched.has (postId) ? weight : 0)
+		    },
+		    0) / priorWeightTotal))
+	}) ()
+	const priorBonus = (() => {
+	  if (priorSplitScore == null)
+	    return 0
+
+	  return Math.max (0, .22 - priorSplitScore) * -18
+	}) ()
 	const infoGainBonus = -Math.min (1.2, infoGain) * 4
 
 	return { question,
@@ -2052,9 +2075,7 @@ const chooseQuestion = (
       questions.filter (question => !(askedIds.has (question.id)))
   const ranked = rank (unansweredQuestions, scoredPosts, normalisedWeightedPosts)
   const pool = (
-      ranked.some (item => !(item.narrow))
-	? ranked.filter (item => !(item.narrow))
-	: ranked)
+      ranked.some (item => !(item.narrow)) ? ranked.filter (item => !(item.narrow)) : ranked)
       .slice (0, 16)
 
   if (pool.length === 0)
@@ -2133,10 +2154,7 @@ const chooseWinningRunQuestion = ({
       })
       .map (question => {
 	const expected = expectedAnswerForQuestion (question, targetPost)
-	const priority =
-	    expected == null
-	      ? null
-	      : winningRunPriorityFor (expected)
+	const priority = expected == null ? null : winningRunPriorityFor (expected)
 	if (priority == null)
 	  return null
 
@@ -2148,9 +2166,7 @@ const chooseWinningRunQuestion = ({
 	    question,
 	    dynamicMatchIndex })
 	const matchingCount =
-	    expected === 'yes' || expected === 'partial'
-	      ? yesCount
-	      : posts.length - yesCount
+	    expected === 'yes' || expected === 'partial' ? yesCount : posts.length - yesCount
 
 	return {
 	    question,
@@ -2291,12 +2307,15 @@ const isWinningRunActive = (
 const winningRunQuestionCount = (
     answers:                    GekanatorAnswerLog[],
     winningRunStartAnswerCount: number | null,
-): number => winningRunStartAnswerCount == null
-    ? 0
-    : answers
-	.slice (winningRunStartAnswerCount)
-	.filter (answer => answer.questionMode === 'winning_run')
-	.length
+): number => {
+  if (winningRunStartAnswerCount == null)
+    return 0
+
+  return answers
+      .slice (winningRunStartAnswerCount)
+      .filter (answer => answer.questionMode === 'winning_run')
+      .length
+}
 
 
 const nextQuestionPlanFor = (
@@ -2335,10 +2354,7 @@ const nextQuestionPlanFor = (
      questionMode: QuestionMode
      winningRunTargetId: number | null
      winningRunStartAnswerCount: number | null } => {
-  const guessablePosts =
-      eligiblePosts.length > 0
-      ? eligiblePosts
-      : availablePosts
+  const guessablePosts = eligiblePosts.length > 0 ? eligiblePosts : availablePosts
 
   const checkpointGuess =
       answers.length > 0
@@ -2366,22 +2382,25 @@ const nextQuestionPlanFor = (
 	  winningRunStartAnswerCount }
     }
 
-  const nextWinningRunTargetId =
-      eligiblePosts.length === 1
-      ? eligiblePosts[0]?.id ?? null
-      : null
-  const nextWinningRunStartAnswerCount =
-      nextWinningRunTargetId == null
-      ? null
-      : ((isWinningRunActive (winningRunTargetId, winningRunStartAnswerCount)
-	  && winningRunTargetId === nextWinningRunTargetId
-	  && winningRunStartAnswerCount != null)
-	 ? winningRunStartAnswerCount
-	 : answers.length)
-  const nextWinningRunTargetPost =
-      nextWinningRunTargetId == null
-      ? null
-      : posts.find (post => post.id === nextWinningRunTargetId) ?? null
+  const nextWinningRunTargetId = eligiblePosts.length === 1 ? eligiblePosts[0]?.id ?? null : null
+  const nextWinningRunStartAnswerCount = (() => {
+    if (nextWinningRunTargetId == null)
+      return null
+    if (
+	isWinningRunActive (winningRunTargetId, winningRunStartAnswerCount)
+	&& winningRunTargetId === nextWinningRunTargetId
+	&& winningRunStartAnswerCount != null
+    )
+      return winningRunStartAnswerCount
+
+    return answers.length
+  }) ()
+  const nextWinningRunTargetPost = (() => {
+    if (nextWinningRunTargetId == null)
+      return null
+
+    return posts.find (post => post.id === nextWinningRunTargetId) ?? null
+  }) ()
   const buildQuestionsForPosts = (scopePosts: Post[]): GekanatorQuestion[] =>
       buildQuestionsForCandidateIds ({
 	  candidateIds: scopePosts.map (post => post.id),
@@ -2580,12 +2599,12 @@ const backgroundPostsFor = ({
 }): Post[] => {
   const focusPosts =
       phase === 'end' || phase === 'review' || phase === 'learned'
-	? [reviewCorrectPost, reviewGuessedPost].filter ((post): post is Post => post != null)
-	: phase === 'guess'
-	  ? [displayedGuess, ...eligiblePosts].filter ((post): post is Post => post != null)
-	  : eligiblePosts.length > 0
-	    ? eligiblePosts
-	    : availablePosts
+      ? [reviewCorrectPost, reviewGuessedPost].filter ((post): post is Post => post != null)
+      : phase === 'guess'
+      ? [displayedGuess, ...eligiblePosts].filter ((post): post is Post => post != null)
+      : eligiblePosts.length > 0
+      ? eligiblePosts
+      : availablePosts
 
   return [...new Map (focusPosts.map (post => [post.id, post])).values ()]
 }
@@ -2634,20 +2653,20 @@ const GekanatorBackdrop: FC<{
 	  { x: -33.333333, y: -33.333333 }],
       [])
   const guessThumbnail =
-      phase === 'guess' && displayedGuess
-	? backgroundThumbnailUrl (displayedGuess)
-	: null
+      phase === 'guess' && displayedGuess ? backgroundThumbnailUrl (displayedGuess) : null
   const isWinningRunBackdrop =
       !(guessThumbnail)
       && phase === 'question'
       && winningRunTargetPost != null
       && Boolean (backgroundThumbnailUrl (winningRunTargetPost))
-  const backdropMode =
-      guessThumbnail
-	? 'guess'
-	: isWinningRunBackdrop
-	  ? 'winning_run'
-	  : 'normal'
+  const backdropMode = (() => {
+    if (guessThumbnail)
+      return 'guess'
+    if (isWinningRunBackdrop)
+      return 'winning_run'
+
+    return 'normal'
+  }) ()
 
   const normalVisiblePosts = useMemo (
       () => posts
@@ -2665,9 +2684,10 @@ const GekanatorBackdrop: FC<{
 	if (mode === 'winning_run' || mode === 'guess')
 	  return { columns: 8, rows: 8, opacity: motionMode === 'calm' ? .18 : .24 }
 
-	return motionMode === 'calm'
-	  ? { columns: 7, rows: 7, opacity: .14 }
-	  : { columns: 10, rows: 10, opacity: .2 }
+	if (motionMode === 'calm')
+	  return { columns: 7, rows: 7, opacity: .14 }
+
+	return { columns: 10, rows: 10, opacity: .2 }
       },
       [motionMode])
 
@@ -2723,10 +2743,12 @@ const GekanatorBackdrop: FC<{
 	      ?? directions[0],
       [visualSeed, directions])
 
-  const marqueeDuration =
-      backdropMode === 'winning_run'
-	? motionMode === 'calm' ? 28 : 20
-	: motionMode === 'calm' ? 34 : 24
+  const marqueeDuration = (() => {
+    if (backdropMode === 'winning_run')
+      return motionMode === 'calm' ? 28 : 20
+
+    return motionMode === 'calm' ? 34 : 24
+  }) ()
   const tileFlipDuration = motionMode === 'calm' ? .6 : .45
   const x = useMotionValue (0)
   const y = useMotionValue (0)
@@ -2944,6 +2966,13 @@ const GekanatorBackdrop: FC<{
 	<div className="absolute inset-0 bg-gradient-to-br from-yellow-50 via-white
 			to-pink-50 dark:from-red-950 dark:via-red-975 dark:to-red-900"/>)
 
+  const backdropTransition: Transition = (() => {
+    if (displayedBackdropMode === 'winning_run' || displayedBackdropMode === 'guess')
+      return { duration: motionMode === 'calm' ? .95 : .75, ease: [.16, 1, .3, 1] }
+
+    return { duration: .2 }
+  }) ()
+
   return (
       <div className="fixed [inset:48px_0_0_0] z-0 overflow-hidden pointer-events-none">
 	<div className="absolute inset-0 flex items-center justify-center">
@@ -2958,11 +2987,7 @@ const GekanatorBackdrop: FC<{
 		animate={{ scale: renderedScale,
 			   x: displayedBackdropMode === 'guess' ? guessFocusOffset.x : '0%',
 			   y: displayedBackdropMode === 'guess' ? guessFocusOffset.y : '0%' }}
-		transition={(displayedBackdropMode === 'winning_run'
-			     || displayedBackdropMode === 'guess')
-			    ? { duration: motionMode === 'calm' ? .95 : .75,
-				ease: [.16, 1, .3, 1] }
-			    : { duration: .2 }}>
+		transition={backdropTransition}>
 	      {Array.from ({ length: 9 }, (_, duplicate) => {
 		const column = duplicate % 3
 		const row = Math.floor (duplicate / 3)
@@ -2988,20 +3013,24 @@ const GekanatorBackdrop: FC<{
 				index % Math.max (displayedThumbnails.length, 1)]
 			const frontThumbnail =
 			    isFlippingTiles
-			      ? fromThumbnails[index % Math.max (fromThumbnails.length, 1)]
-			      : currentThumbnail
+			    ? fromThumbnails[index % Math.max (fromThumbnails.length, 1)]
+			    : currentThumbnail
 			const backThumbnail =
 			    isFlippingTiles
-			      ? toThumbnails[index % Math.max (toThumbnails.length, 1)]
-			      : currentThumbnail
+			    ? toThumbnails[index % Math.max (toThumbnails.length, 1)]
+			    : currentThumbnail
 			const thumbnail =
 			    displayedBackdropMode === 'winning_run'
 			    || displayedBackdropMode === 'guess'
-			      ? nextThumbnails[index % Math.max (nextThumbnails.length, 1)]
-			      : currentThumbnail
+			    ? nextThumbnails[index % Math.max (nextThumbnails.length, 1)]
+			    : currentThumbnail
 			if (!(thumbnail) || !(frontThumbnail) || !(backThumbnail))
 			  return null
 
+			const imageSource = ['intro', 'end'].includes (phase) ? mascotAsset : thumbnail
+			const showStaticTile =
+			    displayedBackdropMode !== 'normal' || !(isFlippingTiles)
+
 			return (
 			    <motion.div
 				key={`${ duplicate }:${ index }`}
@@ -3009,16 +3038,14 @@ const GekanatorBackdrop: FC<{
 				layout={displayedBackdropMode !== 'normal'}
 				transition={{ duration: tileFlipDuration, ease: 'easeInOut' }}
 				style={{ perspective: 1600 }}>
-			      {(displayedBackdropMode !== 'normal' || !(isFlippingTiles))
-			       ? (
+			      {showStaticTile && (
 				  <img
-				      src={['intro', 'end'].includes (phase)
-					   ? mascotAsset
-					   : thumbnail}
+				      src={imageSource}
 				      alt=""
 				      className="absolute inset-0 h-full w-full object-cover"
 				      style={{ opacity: renderedSettings.opacity }}/>)
-			       : (
+			      }
+			      {!(showStaticTile) && (
 				  <motion.div
 				      className="absolute inset-0"
 				      initial={{ rotateY: 0 }}
@@ -3095,9 +3122,12 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
   const [askedQuestionBank, setAskedQuestionBank] = useState<GekanatorQuestion[]> (
       () => (storedGame?.askedQuestionBank ?? []).map (restoreGekanatorQuestion))
   const [storedAskedQuestionBankIds, setStoredAskedQuestionBankIds] = useState<string[]> (
-      (storedGame?.askedQuestionBank?.length ?? 0) > 0
-	? []
-	: storedGame?.askedQuestionBankIds ?? [])
+      () => {
+	if ((storedGame?.askedQuestionBank?.length ?? 0) > 0)
+	  return []
+
+	return storedGame?.askedQuestionBankIds ?? []
+      })
   const [search, setSearch] = useState (storedGame?.search ?? '')
   const [selectingCorrectPost, setSelectingCorrectPost] = useState (
       storedGame?.selectingCorrectPost ?? false)
@@ -3397,9 +3427,12 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 	  userPriorWeights, materialIndex, acceptedQuestionMatchIndex,
 	  lastGuessQuestionCount, winningRunTargetId, winningRunStartAnswerCount])
   const winningRunTargetPost = useMemo (
-      () => questionPlan.winningRunTargetId == null
-	  ? null
-	  : posts.find (post => post.id === questionPlan.winningRunTargetId) ?? null,
+      () => {
+	if (questionPlan.winningRunTargetId == null)
+	  return null
+
+	return posts.find (post => post.id === questionPlan.winningRunTargetId) ?? null
+      },
       [posts, questionPlan.winningRunTargetId])
   const winningRunQuestionsAsked = winningRunQuestionCount (
       answers,
@@ -3420,21 +3453,21 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
       [eligiblePosts, scores])
   const currentQuestion = questionPlan.question
   const answerPreviews = useMemo (
-      () => isAdmin && currentQuestion
-	  ? answerOptions.map (option => previewAnswer ({
-	      posts: eligiblePosts,
-	      scores,
-	      question: currentQuestion,
-	      answer: option.value,
-	      materialIndex,
-	      matchIndex: acceptedQuestionMatchIndex }))
-	  : [],
+      () => {
+	if (!(isAdmin) || !(currentQuestion))
+	  return []
+
+	return answerOptions.map (option => previewAnswer ({
+	    posts: eligiblePosts,
+	    scores,
+	    question: currentQuestion,
+	    answer: option.value,
+	    materialIndex,
+	    matchIndex: acceptedQuestionMatchIndex }))
+      },
       [isAdmin, currentQuestion, eligiblePosts, materialIndex,
 	  acceptedQuestionMatchIndex, scores])
-  const guessablePosts =
-      eligiblePosts.length > 0
-	? eligiblePosts
-	: availablePosts
+  const guessablePosts = eligiblePosts.length > 0 ? eligiblePosts : availablePosts
   const guessConfidences = useMemo (
       () => confidencesFor (guessablePosts, scores),
       [guessablePosts, scores])
@@ -3446,17 +3479,22 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
       posts.find (post => post.id === reviewGuessedPostId) ?? null
   const reviewCorrectPost =
       posts.find (post => post.id === reviewCorrectPostId) ?? null
-  const effectiveResultWon =
-      resultWon
-      ?? ((reviewGuessedPostId != null && reviewCorrectPostId != null)
-	  ? reviewGuessedPostId === reviewCorrectPostId
-	  : null)
-  const effectiveBackgroundMotionMode =
-      backgroundMotionMode === 'off'
-      ? 'off'
-      : (prefersReducedMotion
-	 ? 'calm'
-	 : backgroundMotionMode)
+  const effectiveResultWon = (() => {
+    if (resultWon != null)
+      return resultWon
+    if (reviewGuessedPostId == null || reviewCorrectPostId == null)
+      return null
+
+    return reviewGuessedPostId === reviewCorrectPostId
+  }) ()
+  const effectiveBackgroundMotionMode = (() => {
+    if (backgroundMotionMode === 'off')
+      return 'off'
+    if (prefersReducedMotion)
+      return 'calm'
+
+    return backgroundMotionMode
+  }) ()
   const backgroundPosts = useMemo (
       () => backgroundPostsFor ({
 	      phase,
@@ -3584,10 +3622,12 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
     let recoveredStepCount = nextRecoveryStepCount
     const nextAskedQuestionById =
 	new Map (nextAskedQuestionBank.map (question => [question.id, question]))
-    const answerCountAtRecovery =
-	allowPreQuestionRecovery
-	  ? nextAnswers.length
-	  : Math.max (nextAnswers.length - 1, 0)
+    const answerCountAtRecovery = (() => {
+      if (allowPreQuestionRecovery)
+	return nextAnswers.length
+
+      return Math.max (nextAnswers.length - 1, 0)
+    }) ()
     let recoveredScores = recalculateScores ({
 	posts,
 	questions: nextAskedQuestionBank,
@@ -3863,12 +3903,14 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
   }
 
   const finishGame = (correctPostId: number) => {
-    const guessedPostId =
-	phase === 'end' || phase === 'review'
-	  ? reviewGuessedPostId
-	  : phase === 'continue'
-	  ? lastRejectedGuessId ?? displayedGuess?.id
-	  : displayedGuess?.id ?? lastRejectedGuessId
+    const guessedPostId = (() => {
+      if (phase === 'end' || phase === 'review')
+	return reviewGuessedPostId
+      if (phase === 'continue')
+	return lastRejectedGuessId ?? displayedGuess?.id
+
+      return displayedGuess?.id ?? lastRejectedGuessId
+    }) ()
     if (!(guessedPostId))
       return
 
@@ -4198,13 +4240,18 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
   const resultDialogue = effectiveResultWon ? winDialogue : loseDialogue
 
   const dialogue = phase === 'learned' ? resultDialogue : introDialogue
-  const saveStatusMessage =
-      saved
-      && learnedExampleCount != null
-	? learnedExampleCount > 0
-	  ? `${ learnedExampleCount }件の回答を学習しました`
-	  : null
-	: null
+  const introLoadingMessage =
+      phase === 'intro' ? '投稿を読み込んでいます……' : '前回のグカネータ状態を復元しています……'
+  const questionSuggestionTitle =
+      questionSuggestionEntryMode === 'search' ? 'まず既存質問を探してください。' : '新しい質問を追加します。'
+  const saveStatusMessage = (() => {
+    if (!(saved) || learnedExampleCount == null)
+      return null
+    if (learnedExampleCount <= 0)
+      return null
+
+    return `${ learnedExampleCount }件の回答を学習しました`
+  }) ()
 
   const introLoading = isLoading || acceptedQuestionsLoading
   const readyToStart =
@@ -4323,18 +4370,23 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 		</span>
 		{[{ mode: 'off' as const, label: 'オフ' },
 		  { mode: 'on' as const, label: 'オン' }]
-		 .map (({ mode, label }) => (
-		    <button
-			key={mode}
-			type="button"
-			className={cn (
-			    'rounded-full px-2.5 py-1 transition-colors',
-			    backgroundMotionMode === mode
-			      ? 'bg-pink-600 text-white'
-			      : 'text-neutral-600 hover:bg-yellow-100 dark:text-neutral-300 dark:hover:bg-red-900')}
-			onClick={() => setBackgroundMotionMode (mode)}>
-		      {label}
-		    </button>))}
+		 .map (({ mode, label }) => {
+		   const modeClass =
+		       backgroundMotionMode === mode
+		       ? 'bg-pink-600 text-white'
+		       : 'text-neutral-600 hover:bg-yellow-100 dark:text-neutral-300 dark:hover:bg-red-900'
+
+		   return (
+		       <button
+			   key={mode}
+			   type="button"
+			   className={cn (
+			       'rounded-full px-2.5 py-1 transition-colors',
+			       modeClass)}
+			   onClick={() => setBackgroundMotionMode (mode)}>
+			 {label}
+		       </button>)
+		 })}
 		{prefersReducedMotion && effectiveBackgroundMotionMode !== 'off' && (
 		    <span className="ml-2 text-[11px] text-neutral-500 dark:text-neutral-400">
 		      端末設定により控えめ表示
@@ -4365,9 +4417,7 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 
 		{introLoading && (
 		    <p>
-		      {phase === 'intro'
-		       ? '投稿を読み込んでいます……'
-		       : '前回のグカネータ状態を復元しています……'}
+		      {introLoadingMessage}
 		    </p>)}
 		{(Boolean (error) || Boolean (acceptedQuestionsError))
 		    && <p>グカネータの質問データを読み込めませんでした．</p>}
@@ -4602,9 +4652,9 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 
 		      <div className="space-y-2">
 			<div className="font-bold">正解の投稿</div>
-			{reviewCorrectPost
-			 ? <PostMiniCard post={reviewCorrectPost}/>
-			 : <p className="text-sm text-red-600">正解投稿を選んでください。</p>}
+			{reviewCorrectPost && <PostMiniCard post={reviewCorrectPost}/>}
+			{!(reviewCorrectPost) && (
+			    <p className="text-sm text-red-600">正解投稿を選んでください。</p>)}
 			<button
 			    type="button"
 			    className="rounded border border-yellow-300 px-3 py-2
@@ -4700,9 +4750,9 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 
 		      <div className="space-y-2">
 			<div className="font-bold">正解の投稿</div>
-			{reviewCorrectPost
-			 ? <PostMiniCard post={reviewCorrectPost}/>
-			 : <p className="text-sm text-red-600">正解投稿を選んでください。</p>}
+			{reviewCorrectPost && <PostMiniCard post={reviewCorrectPost}/>}
+			{!(reviewCorrectPost) && (
+			    <p className="text-sm text-red-600">正解投稿を選んでください。</p>)}
 			<button
 			    type="button"
 			    className="rounded border border-yellow-300 px-3 py-2
@@ -4806,14 +4856,9 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 		    <div className="space-y-4">
 		      <div>
 			<p className="text-sm text-neutral-500">質問追加</p>
-			<p className="text-xl font-bold">
-			  {questionSuggestionEntryMode === 'search'
-			   ? 'まず既存質問を探してください。'
-			   : '新しい質問を追加します。'}
-			</p>
+			<p className="text-xl font-bold">{questionSuggestionTitle}</p>
 		      </div>
-		      {questionSuggestionEntryMode === 'search'
-		       ? (
+		      {questionSuggestionEntryMode === 'search' && (
 			  <>
 			    <label className="block space-y-2">
 			      <span className="font-bold">既存質問を検索</span>
@@ -4831,21 +4876,26 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 				<div className="space-y-2">
 				  <div className="font-bold">既存質問候補</div>
 				  <div className="max-h-64 space-y-2 overflow-y-auto">
-				    {searchableSuggestedQuestions.map (question => (
-					<button
-					    key={question.id}
-					    type="button"
-					    className={cn (
-						'block w-full rounded border px-3 py-2 text-left',
-						questionSuggestionSelectedId === (question.recordId ?? null)
-						  ? 'border-pink-600 bg-pink-50 dark:bg-red-900/50'
-						  : 'border-yellow-200 hover:bg-yellow-100 dark:border-red-800 dark:hover:bg-red-900')}
-					    onClick={() => {
-					      setQuestionSuggestionSelectedId (question.recordId ?? null)
-					      setQuestionSuggestion ('')
-					    }}>
-					  <div className="font-bold">{question.text}</div>
-					</button>))}
+				    {searchableSuggestedQuestions.map (question => {
+				      const questionClass =
+					  questionSuggestionSelectedId === (question.recordId ?? null)
+					  ? 'border-pink-600 bg-pink-50 dark:bg-red-900/50'
+					  : 'border-yellow-200 hover:bg-yellow-100 dark:border-red-800 dark:hover:bg-red-900'
+
+				      return (
+					  <button
+					      key={question.id}
+					      type="button"
+					      className={cn (
+						  'block w-full rounded border px-3 py-2 text-left',
+						  questionClass)}
+					      onClick={() => {
+						setQuestionSuggestionSelectedId (question.recordId ?? null)
+						setQuestionSuggestion ('')
+					      }}>
+					    <div className="font-bold">{question.text}</div>
+					  </button>)
+				    })}
 				  </div>
 				</div>)}
 			    {selectedSuggestedQuestion && (
@@ -4873,7 +4923,8 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 				  </div>
 				</div>)}
 			  </>)
-		       : (
+		      }
+		      {questionSuggestionEntryMode === 'new' && (
 			  <div className="space-y-2">
 			    <div className="font-bold">新規質問</div>
 			    <textarea
@@ -4975,18 +5026,24 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 				  </div>
 				  <div className="font-bold">{question.text}</div>
 				  <div className="mt-3 flex flex-wrap gap-2">
-				    {answerOptions.map (option => (
-					<button
-					    key={option.value}
-					    type="button"
-					    className={cn (
-						'rounded border px-3 py-2',
-						extraQuestionAnswers[String (question.id)] === option.value
-						  ? 'border-pink-600 bg-pink-600 text-white'
-						  : 'border-yellow-300 hover:bg-yellow-100 dark:border-red-700 dark:hover:bg-red-900')}
-					    onClick={() => answerExtraQuestion (question.id, option.value)}>
-					  {option.label}
-					</button>))}
+				    {answerOptions.map (option => {
+				      const optionClass =
+					  extraQuestionAnswers[String (question.id)] === option.value
+					  ? 'border-pink-600 bg-pink-600 text-white'
+					  : 'border-yellow-300 hover:bg-yellow-100 dark:border-red-700 dark:hover:bg-red-900'
+
+				      return (
+					  <button
+					      key={option.value}
+					      type="button"
+					      className={cn (
+						  'rounded border px-3 py-2',
+						  optionClass)}
+					      onClick={() =>
+						answerExtraQuestion (question.id, option.value)}>
+					    {option.label}
+					  </button>)
+				    })}
 				  </div>
 				</div>))}
 			  </div>)}