#371

backend/app/controllers/gekanator_games_controller.rb

@@ -192,7 +192,10 @@ class GekanatorGamesController < ApplicationController
       answer_value = answer['answer'].to_s
       next if answer_value.blank? || answer_value == 'unknown'
 
-      question = accepted_questions[answer['question_id'].to_s]
+      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 =
@@ -251,6 +254,7 @@ class GekanatorGamesController < ApplicationController
   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'
 
@@ -258,4 +262,11 @@ class GekanatorGamesController < ApplicationController
     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

frontend/src/pages/GekanatorPage.tsx

@@ -110,6 +110,7 @@ type StoredGekanatorGame = {
     savedGameId:                 number | null
     learnedExampleCount?:        number | null
     gameSeed?:                   string
+    questionSuggestionEntryMode?: 'search' | 'new'
     questionSuggestionSearch?:   string
     questionSuggestionSelectedId?: number | null
     questionSuggestion:          string
@@ -141,6 +142,10 @@ type QuestionBuildMode =
     | 'split'
     | 'confirmation'
 
+type QuestionSuggestionEntryMode =
+    | 'search'
+    | 'new'
+
 type MascotState =
     | 'idle'
     | 'thinking_far'
@@ -256,6 +261,7 @@ const normalizeStoredGame = (game: StoredGekanatorGame): StoredGekanatorGame =>
   winningRunTargetId: game.winningRunTargetId ?? null,
   winningRunStartAnswerCount: game.winningRunStartAnswerCount ?? null,
   learnedExampleCount: game.learnedExampleCount ?? null,
+  questionSuggestionEntryMode: game.questionSuggestionEntryMode ?? 'search',
   questionSuggestionSearch: game.questionSuggestionSearch ?? '',
   questionSuggestionSelectedId: game.questionSuggestionSelectedId ?? null,
   askedQuestionBank: game.askedQuestionBank?.map (question => ({
@@ -1125,17 +1131,31 @@ const applyQuestionAnswerDeltaToScores = ({
   if (!(questionUsesPostSimilarityGraphForScoring (question)))
     return
 
+  // `post_similarities` is the propagation graph. Directly matched posts
+  // get only the base delta; only non-direct neighbors get `base delta * cos`.
+  // When several matched posts point at the same neighbor, keep the largest
+  // absolute propagated contribution instead of summing all of them.
+  const propagatedDeltaByPostId = new Map<number, number> ()
   matched.forEach (postId => {
     const post = materialIndex.postById.get (postId)
     post?.postSimilarityEdges?.forEach (edge => {
       if (!Number.isFinite (edge.cos) || edge.cos <= 0)
 	return
+      if (matched.has (edge.targetPostId))
+	return
 
-      nextScores.set (
-	  edge.targetPostId,
-	  (nextScores.get (edge.targetPostId) ?? 0) + baseDelta * edge.cos)
+      const propagatedDelta = baseDelta * edge.cos
+      const current = propagatedDeltaByPostId.get (edge.targetPostId)
+      if (current === undefined || Math.abs (propagatedDelta) > Math.abs (current))
+	propagatedDeltaByPostId.set (edge.targetPostId, propagatedDelta)
     })
   })
+
+  propagatedDeltaByPostId.forEach ((propagatedDelta, postId) => {
+    nextScores.set (
+	postId,
+	(nextScores.get (postId) ?? 0) + propagatedDelta)
+  })
 }
 
 const buildIndexedQuestion = (
@@ -1294,7 +1314,7 @@ const buildQuestionsForCandidateIds = (
 	  .forEach (([term]) => {
 	    addQuestion (buildIndexedQuestion ({
 		condition: { type: 'title-contains', text: String (term) },
-		text: `題名に「${ term }」が含まれる?`,
+		text: `タイトルに「${ term }」が含まれる?`,
 		kind: 'title',
 		priorityWeight: .99,
 		materialIndex }))
@@ -1313,7 +1333,7 @@ const buildQuestionsForCandidateIds = (
       if (asciiCount > 0 && asciiCount < total)
 	addQuestion (buildIndexedQuestion ({
 	    condition: { type: 'title-has-ascii' },
-	    text: '題名に英数字が混じっている?',
+	    text: 'タイトルに英数字が混じっている?',
 	    kind: 'title',
 	    priorityWeight: .68,
 	    materialIndex }))
@@ -1367,7 +1387,7 @@ const buildQuestionsForCandidateIds = (
 	  .forEach (term => {
 	    addQuestion (buildIndexedQuestion ({
 		condition: { type: 'title-contains', text: term },
-		text: `題名に「${ term }」が含まれる?`,
+		text: `タイトルに「${ term }」が含まれる?`,
 		kind: 'title',
 		priorityWeight: .99,
 		materialIndex }))
@@ -1386,7 +1406,7 @@ const buildQuestionsForCandidateIds = (
       if (materialIndex.titleAsciiPostIds.has (targetPostId))
 	addQuestion (buildIndexedQuestion ({
 	    condition: { type: 'title-has-ascii' },
-	    text: '題名に英数字が混じっている?',
+	    text: 'タイトルに英数字が混じっている?',
 	    kind: 'title',
 	    priorityWeight: .68,
 	    materialIndex }))
@@ -1415,6 +1435,8 @@ const candidatePostsForState = ({
     recoveredCandidatePosts: Map<number, number>
 }): Post[] => {
   const dynamicMatchIndex = new Map<string, Set<number>> ()
+  const answerAllowsHardFilter = (answer: GekanatorAnswerValue): boolean =>
+      answer === 'yes' || answer === 'no'
 
   return posts.filter (post => {
     if (rejectedPostIds.has (post.id))
@@ -1427,7 +1449,7 @@ const candidatePostsForState = ({
 	return true
       if (softenedQuestionIds.has (answer.questionId))
 	return true
-      if (!(answer.answer === 'yes' || answer.answer === 'no'))
+      if (!(answerAllowsHardFilter (answer.answer)))
 	return true
 
       const question = questionById.get (answer.questionId)
@@ -2717,6 +2739,7 @@ const GekanatorBackdrop: FC<{
   const marqueeTransform = useMotionTemplate`translate(${ x }%, ${ y }%)`
   const [activeDirection, setActiveDirection] = useState (nextDirection)
   const activeDirectionRef = useRef (activeDirection)
+  const guessAnimationControlsRef = useRef<ReturnType<typeof animate>[]> ([])
   const flipTimerRef = useRef<number | null> (null)
   const [displayedBackdropMode, setDisplayedBackdropMode] =
       useState<'normal' | 'winning_run' | 'guess'> (backdropMode)
@@ -2731,15 +2754,30 @@ const GekanatorBackdrop: FC<{
   const [flipVisualSeed, setFlipVisualSeed] = useState (visualSeed)
   const [isFlippingTiles, setIsFlippingTiles] = useState (false)
   const [isCrossfading, setIsCrossfading] = useState (false)
-  const renderedSettings = settingsForMode (displayedBackdropMode)
-  const renderedTileCount =
-      renderedSettings.columns * renderedSettings.rows
-  const renderedScale = scaleForMode (displayedBackdropMode, displayedWinningRunCount)
-  const isGuessPresentation =
-      phase === 'guess' || backdropMode === 'guess' || displayedBackdropMode === 'guess'
+
+  const isLeavingGuessBackdrop = displayedBackdropMode === 'guess' && backdropMode !== 'guess'
+
+  const renderBackdropMode = isLeavingGuessBackdrop ? backdropMode : displayedBackdropMode
+
+  const renderWinningRunCount = (isLeavingGuessBackdrop
+				 ? winningRunQuestionCount
+				 : displayedWinningRunCount)
+
+  const renderThumbnails = isLeavingGuessBackdrop ? nextThumbnails : displayedThumbnails
+
+  const renderIsCrossfading = isCrossfading && !(isLeavingGuessBackdrop)
+
+  const renderedSettings = settingsForMode (renderBackdropMode)
+  const renderedTileCount = renderedSettings.columns * renderedSettings.rows
+  const renderedScale = scaleForMode (renderBackdropMode, renderWinningRunCount)
+
+  const isGuessPresentation = backdropMode === 'guess'
   const crossfadeDuration = motionMode === 'calm' ? .95 : .75
 
   useEffect (() => {
+    guessAnimationControlsRef.current.forEach (control => control.stop ())
+    guessAnimationControlsRef.current = []
+
     if (motionMode === 'off')
       return
 
@@ -2752,9 +2790,11 @@ const GekanatorBackdrop: FC<{
     const controls = [
 	animate (x, 0, { duration, ease }),
 	animate (y, 0, { duration, ease })]
+    guessAnimationControlsRef.current = controls
 
     return () => {
       controls.forEach (control => control.stop ())
+      guessAnimationControlsRef.current = []
     }
   }, [isGuessPresentation, motionMode, visualSeed, x, y])
 
@@ -2771,13 +2811,21 @@ const GekanatorBackdrop: FC<{
 
     if (motionMode === 'off' || nextThumbnails.length === 0)
       {
+	guessAnimationControlsRef.current.forEach (control => control.stop ())
+	guessAnimationControlsRef.current = []
 	x.set (0)
 	y.set (0)
 	return
       }
 
     if (isGuessPresentation)
-      return
+      {
+	guessAnimationControlsRef.current.forEach (control => control.stop ())
+	guessAnimationControlsRef.current = []
+	x.set (0)
+	y.set (0)
+	return
+      }
 
     const speed = 33.333333 / marqueeDuration
     let animationFrame: number
@@ -2795,8 +2843,7 @@ const GekanatorBackdrop: FC<{
     animationFrame = window.requestAnimationFrame (tick)
 
     return () => window.cancelAnimationFrame (animationFrame)
-  }, [
-      x,
+  }, [x,
       y,
       marqueeDuration,
       motionMode,
@@ -2809,67 +2856,86 @@ const GekanatorBackdrop: FC<{
       setActiveDirection (nextDirection)
     }
 
-    if (flipTimerRef.current !== null) {
-      window.clearTimeout (flipTimerRef.current)
-      flipTimerRef.current = null
-    }
+    if (flipTimerRef.current !== null)
+      {
+	window.clearTimeout (flipTimerRef.current)
+	flipTimerRef.current = null
+      }
 
-    if (motionMode === 'off') {
-      applyDirection ()
-      setIsFlippingTiles (false)
-      setIsCrossfading (false)
-      setFlipVisualSeed (visualSeed)
-      return
-    }
+    if (motionMode === 'off')
+      {
+	applyDirection ()
+	setIsFlippingTiles (false)
+	setIsCrossfading (false)
+	setFlipVisualSeed (visualSeed)
+	return
+      }
 
-    if (backdropMode === 'guess' && guessThumbnail) {
-      setIsFlippingTiles (false)
-      setIsCrossfading (false)
-      setDisplayedBackdropMode ('guess')
-      setDisplayedWinningRunCount (winningRunQuestionCount)
-      setDisplayedThumbnails (nextThumbnails)
-      setFromThumbnails (nextThumbnails)
-      setToThumbnails (nextThumbnails)
-      setFlipVisualSeed (visualSeed)
-      return
-    }
+    if (backdropMode === 'guess' && guessThumbnail)
+      {
+	setIsFlippingTiles (false)
+	setIsCrossfading (false)
+	setDisplayedBackdropMode ('guess')
+	setDisplayedWinningRunCount (winningRunQuestionCount)
+	setDisplayedThumbnails (nextThumbnails)
+	setFromThumbnails (nextThumbnails)
+	setToThumbnails (nextThumbnails)
+	setFlipVisualSeed (visualSeed)
+	return
+      }
 
-    if (
-	displayedBackdropMode === 'winning_run'
-	&& backdropMode === 'winning_run'
-    ) {
-      applyDirection ()
-      setDisplayedBackdropMode ('winning_run')
-      setDisplayedWinningRunCount (winningRunQuestionCount)
-      setDisplayedThumbnails (nextThumbnails)
-      setFromThumbnails (nextThumbnails)
-      setToThumbnails (nextThumbnails)
-      setIsFlippingTiles (false)
-      setIsCrossfading (false)
-      setFlipVisualSeed (visualSeed)
-      return
-    }
+    if (displayedBackdropMode === 'winning_run'
+	&& backdropMode === 'winning_run')
+      {
+	applyDirection ()
+	setDisplayedBackdropMode ('winning_run')
+	setDisplayedWinningRunCount (winningRunQuestionCount)
+	setDisplayedThumbnails (nextThumbnails)
+	setFromThumbnails (nextThumbnails)
+	setToThumbnails (nextThumbnails)
+	setIsFlippingTiles (false)
+	setIsCrossfading (false)
+	setFlipVisualSeed (visualSeed)
+	return
+      }
 
-    if (nextThumbnails.length === 0) {
-      applyDirection ()
-      setIsFlippingTiles (false)
-      setIsCrossfading (false)
-      setFlipVisualSeed (visualSeed)
-      return
-    }
+    if (nextThumbnails.length === 0)
+      {
+	applyDirection ()
+	setIsFlippingTiles (false)
+	setIsCrossfading (false)
+	setFlipVisualSeed (visualSeed)
+	return
+      }
+
+    if (displayedBackdropMode === 'guess' && backdropMode !== 'guess')
+      {
+	applyDirection ()
+	x.set (0)
+	y.set (0)
+	setIsFlippingTiles (false)
+	setIsCrossfading (false)
+	setDisplayedBackdropMode (backdropMode)
+	setDisplayedWinningRunCount (winningRunQuestionCount)
+	setDisplayedThumbnails (nextThumbnails)
+	setFromThumbnails (nextThumbnails)
+	setToThumbnails (nextThumbnails)
+	setFlipVisualSeed (visualSeed)
+	return
+      }
 
     const sameTiles =
 	displayedThumbnails.length === nextThumbnails.length
-	&& displayedThumbnails.every (
-	    (thumbnail, index) => thumbnail === nextThumbnails[index])
-    if (sameTiles && flipVisualSeed === visualSeed) {
-      if (
-	  activeDirection.x !== nextDirection.x
-	  || activeDirection.y !== nextDirection.y
-      )
-	applyDirection ()
-      return
-    }
+	&& displayedThumbnails.every ((thumbnail, index) => thumbnail === nextThumbnails[index])
+
+    if (sameTiles && flipVisualSeed === visualSeed)
+      {
+	if (activeDirection.x !== nextDirection.x
+	    || activeDirection.y !== nextDirection.y)
+	  applyDirection ()
+
+	return
+      }
 
     const currentThumbnails =
 	displayedThumbnails.length > 0 ? displayedThumbnails : nextThumbnails
@@ -2895,13 +2961,13 @@ const GekanatorBackdrop: FC<{
     }, (shouldCrossfade ? crossfadeDuration : tileFlipDuration) * 1000)
 
     return () => {
-      if (flipTimerRef.current !== null) {
-	window.clearTimeout (flipTimerRef.current)
-	flipTimerRef.current = null
-      }
+      if (flipTimerRef.current !== null)
+	{
+	  window.clearTimeout (flipTimerRef.current)
+	  flipTimerRef.current = null
+	}
     }
-  }, [
-      motionMode,
+  }, [motionMode,
       backdropMode,
       displayedBackdropMode,
       guessThumbnail,
@@ -2917,118 +2983,120 @@ const GekanatorBackdrop: FC<{
       x,
       y])
 
-  const renderTileSet = ({
-      mode,
-      thumbnails,
-      settings,
-      tileCount,
-      scale,
-      opacity,
-      withFlip,
-  }: {
-      mode:      'normal' | 'winning_run' | 'guess'
-      thumbnails: string[]
-      settings:  { columns: number; rows: number; opacity: number }
-      tileCount: number
-      scale:     number
-      opacity?:  number
-      withFlip?: boolean
-  }) => (
-      <motion.div
-	  className="absolute inset-0"
-	  initial={opacity === undefined
-		   ? undefined
-		   : {
-		       opacity: opacity === 0 ? 1 : 0,
+  const renderTileSet = (
+      { mode,
+	thumbnails,
+	settings,
+	tileCount,
+	scale,
+	opacity,
+	withFlip }: { mode:       'normal' | 'winning_run' | 'guess'
+		      thumbnails: string[]
+		      settings:   { columns: number; rows: number; opacity: number }
+		      tileCount:  number
+		      scale:      number
+		      opacity?:   number
+		      withFlip?:  boolean }) => {
+    const guessModeFlg = mode === 'guess'
+
+    return (
+	<motion.div
+	    className="absolute inset-0"
+	    initial={guessModeFlg
+		     ? false
+		     : (opacity == null
+		        ? undefined
+		        : { opacity: opacity === 0 ? 1 : 0, scale, x: '0%', y: '0%' })}
+	    animate={{ opacity: opacity ?? 1,
 		       scale,
-		       x: mode === 'guess' ? guessFocusOffset.x : '0%',
-		       y: mode === 'guess' ? guessFocusOffset.y : '0%' }}
-	  animate={{ opacity: opacity ?? 1, scale,
-		     x: mode === 'guess' ? guessFocusOffset.x : '0%',
-		     y: mode === 'guess' ? guessFocusOffset.y : '0%' }}
-	  transition={(mode === 'winning_run' || mode === 'guess')
-			 ? { duration: crossfadeDuration, ease: [.16, 1, .3, 1] }
-			 : { duration: .2 }}>
-	{Array.from ({ length: 9 }, (_, duplicate) => {
-	  const column = duplicate % 3
-	  const row = Math.floor (duplicate / 3)
+		       x: guessModeFlg ? guessFocusOffset.x : '0%',
+		       y: guessModeFlg ? guessFocusOffset.y : '0%' }}
+	    transition={guessModeFlg
+			? { duration: 0 }
+			: (mode === 'winning_run'
+			   ? { duration: crossfadeDuration, ease: [.16, 1, .3, 1] }
+			   : { duration: .2 })}>
+	  {Array.from ({ length: 9 }, (_, duplicate) => {
+	    const column = duplicate % 3
+	    const row = Math.floor (duplicate / 3)
 
-	  return (
-	      <motion.div
-		  key={`${ mode }:${ duplicate }`}
-		  className="absolute grid overflow-hidden"
-		  layout={mode !== 'normal'}
-		  style={{
-		      left: `${ column * 33.333333 }%`,
-		      top: `${ row * 33.333333 }%`,
-		      width: '33.333333%',
-		      height: '33.333333%',
-		      gridTemplateColumns:
-			  `repeat(${ settings.columns }, minmax(0, 1fr))`,
-		      gridTemplateRows:
-			  `repeat(${ settings.rows }, minmax(0, 1fr))` }}
-		  transition={{ duration: tileFlipDuration, ease: 'easeInOut' }}>
-		{Array.from ({ length: tileCount }, (_, index) => {
-		  const currentThumbnail =
-		      thumbnails[index % Math.max (thumbnails.length, 1)]
-		  const frontThumbnail =
-		      withFlip
-			? fromThumbnails[index % Math.max (fromThumbnails.length, 1)]
-			: currentThumbnail
-		  const backThumbnail =
-		      withFlip
-			? toThumbnails[index % Math.max (toThumbnails.length, 1)]
-			: currentThumbnail
-		  const thumbnail = currentThumbnail
-		  if (!(thumbnail) || !(frontThumbnail) || !(backThumbnail))
-		    return null
+	    return (
+		<motion.div
+		    key={`${ mode }:${ duplicate }`}
+		    className="absolute grid overflow-hidden"
+		    layout={mode === 'winning_run'}
+		    style={{
+			left: `${ column * 33.333333 }%`,
+			top: `${ row * 33.333333 }%`,
+			width: '33.333333%',
+			height: '33.333333%',
+			gridTemplateColumns:
+			    `repeat(${ settings.columns }, minmax(0, 1fr))`,
+			gridTemplateRows:
+			    `repeat(${ settings.rows }, minmax(0, 1fr))` }}
+		    transition={{ duration: tileFlipDuration, ease: 'easeInOut' }}>
+		  {Array.from ({ length: tileCount }, (_, index) => {
+		    const currentThumbnail =
+			thumbnails[index % Math.max (thumbnails.length, 1)]
+		    const frontThumbnail =
+			withFlip
+			  ? fromThumbnails[index % Math.max (fromThumbnails.length, 1)]
+			  : currentThumbnail
+		    const backThumbnail =
+			withFlip
+			  ? toThumbnails[index % Math.max (toThumbnails.length, 1)]
+			  : currentThumbnail
+		    const thumbnail = currentThumbnail
+		    if (!(thumbnail) || !(frontThumbnail) || !(backThumbnail))
+		      return null
 
-		  return (
-		      <motion.div
-			  key={`${ mode }:${ duplicate }:${ index }`}
-			  className="relative overflow-hidden"
-			  layout={mode !== 'normal'}
-			  transition={{ duration: tileFlipDuration, ease: 'easeInOut' }}
-			  style={{ perspective: 1600 }}>
-			{(mode !== 'normal' || !(withFlip))
-			 ? (
-			    <img
-				src={['intro', 'end'].includes (phase)
-				     ? mascotAsset
-				     : thumbnail}
-				alt=""
-				className="absolute inset-0 h-full w-full object-cover"
-				style={{ opacity: settings.opacity }}/>)
-			 : (
-			    <motion.div
-				className="absolute inset-0"
-				initial={{ rotateY: 0 }}
-				animate={{ rotateY: 180 }}
-				transition={{
-				    duration: tileFlipDuration,
-				    ease: 'easeInOut' }}
-				style={{ transformStyle: 'preserve-3d' }}>
+		    return (
+			<motion.div
+			    key={`${ mode }:${ duplicate }:${ index }`}
+			    className="relative overflow-hidden"
+			    layout={mode === 'winning_run'}
+			    transition={{ duration: tileFlipDuration, ease: 'easeInOut' }}
+			    style={{ perspective: 1600 }}>
+			  {(mode !== 'normal' || !(withFlip))
+			   ? (
 			      <img
-				  src={backThumbnail}
+				  src={['intro', 'end'].includes (phase)
+				       ? mascotAsset
+				       : thumbnail}
 				  alt=""
 				  className="absolute inset-0 h-full w-full object-cover"
-				  style={{
-				      backfaceVisibility: 'hidden',
-				      opacity: settings.opacity,
-				      transform: 'rotateY(180deg)' }}/>
-			      <img
-				  src={frontThumbnail}
-				  alt=""
-				  className="absolute inset-0 h-full w-full object-cover"
-				  style={{
-				      backfaceVisibility: 'hidden',
-				      opacity: settings.opacity }}/>
-			    </motion.div>)}
-		      </motion.div>)
-		})}
-	      </motion.div>)
-	})}
-      </motion.div>)
+				  style={{ opacity: settings.opacity }}/>)
+			   : (
+			      <motion.div
+				  className="absolute inset-0"
+				  initial={{ rotateY: 0 }}
+				  animate={{ rotateY: 180 }}
+				  transition={{
+				      duration: tileFlipDuration,
+				      ease: 'easeInOut' }}
+				  style={{ transformStyle: 'preserve-3d' }}>
+				<img
+				    src={backThumbnail}
+				    alt=""
+				    className="absolute inset-0 h-full w-full object-cover"
+				    style={{
+					backfaceVisibility: 'hidden',
+					opacity: settings.opacity,
+					transform: 'rotateY(180deg)' }}/>
+				<img
+				    src={frontThumbnail}
+				    alt=""
+				    className="absolute inset-0 h-full w-full object-cover"
+				    style={{
+					backfaceVisibility: 'hidden',
+					opacity: settings.opacity }}/>
+			      </motion.div>)}
+			</motion.div>)
+		  })}
+		</motion.div>)
+	  })}
+	</motion.div>)
+  }
 
   if (motionMode === 'off' || nextThumbnails.length === 0)
     return (
@@ -3046,15 +3114,16 @@ const GekanatorBackdrop: FC<{
 		  height: 'calc(max(100vw, 100vh) * 3)' }}>
 	    <motion.div
 		className="relative h-full w-full">
-	      {isCrossfading
+	      {renderIsCrossfading
 	       ? (
 		  <>
 		    {renderTileSet ({
 			mode: displayedBackdropMode,
 			thumbnails: fromThumbnails,
-			settings: renderedSettings,
-			tileCount: renderedTileCount,
-			scale: renderedScale,
+			settings: settingsForMode (displayedBackdropMode),
+			tileCount: (settingsForMode (displayedBackdropMode).columns
+				    * settingsForMode (displayedBackdropMode).rows),
+			scale: scaleForMode (displayedBackdropMode, displayedWinningRunCount),
 			opacity: 0 })}
 		    {renderTileSet ({
 			mode: backdropMode,
@@ -3064,13 +3133,14 @@ const GekanatorBackdrop: FC<{
 			scale: scaleForMode (backdropMode, winningRunQuestionCount),
 			opacity: 1 })}
 		  </>)
-	       : renderTileSet ({
-		   mode: displayedBackdropMode,
-		   thumbnails: displayedThumbnails,
-		   settings: renderedSettings,
-		   tileCount: renderedTileCount,
-		   scale: renderedScale,
-		   withFlip: isFlippingTiles })}
+	       : (
+		  renderTileSet ({
+		      mode: renderBackdropMode,
+		      thumbnails: renderThumbnails,
+		      settings: renderedSettings,
+		      tileCount: renderedTileCount,
+		      scale: renderedScale,
+		      withFlip: isFlippingTiles && !(isLeavingGuessBackdrop) }))}
 	    </motion.div>
 	  </motion.div>
 	</div>
@@ -3150,6 +3220,9 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
       storedGame?.savedGameId ?? null)
   const [learnedExampleCount, setLearnedExampleCount] = useState<number | null> (
       storedGame?.learnedExampleCount ?? null)
+  const [questionSuggestionEntryMode, setQuestionSuggestionEntryMode] =
+      useState<QuestionSuggestionEntryMode> (
+	  storedGame?.questionSuggestionEntryMode ?? 'search')
   const [questionSuggestionSearch, setQuestionSuggestionSearch] = useState (
       storedGame?.questionSuggestionSearch ?? '')
   const [questionSuggestionSelectedId, setQuestionSuggestionSelectedId] =
@@ -3190,11 +3263,9 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
       [posts, acceptedQuestions])
 
   useEffect (() => {
-    if (
-	posts.length === 0
+    if (posts.length === 0
 	|| storedAskedQuestionBankIds.length === 0
-	|| !(acceptedQuestionsFetched)
-    )
+	|| !(acceptedQuestionsFetched))
       return
 
     const questionById = new Map (
@@ -3207,8 +3278,7 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 	    .map (questionId => questionById.get (questionId))
 	    .filter ((question): question is GekanatorQuestion => question !== undefined))
     setStoredAskedQuestionBankIds ([])
-  }, [
-      posts,
+  }, [posts,
       storedAskedQuestionBankIds,
       acceptedQuestionsFetched,
       askedQuestionBank,
@@ -3250,6 +3320,7 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 	savedGameId,
 	learnedExampleCount,
 	gameSeed,
+	questionSuggestionEntryMode,
 	questionSuggestionSearch,
 	questionSuggestionSelectedId,
 	questionSuggestion,
@@ -3293,6 +3364,7 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
       savedGameId,
       learnedExampleCount,
       gameSeed,
+      questionSuggestionEntryMode,
       questionSuggestionSearch,
       questionSuggestionSelectedId,
       questionSuggestion,
@@ -3355,6 +3427,28 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 	  question => question.recordId === questionSuggestionSelectedId)
 	  ?? null,
       [acceptedQuestions, questionSuggestionSelectedId])
+  const canSubmitQuestionSuggestion = useMemo (() => {
+    if (!(canPersistGame) || reviewCorrectPostId === null)
+      return false
+
+    if (questionSuggestionEntryMode === 'search')
+      return selectedSuggestedQuestion !== null
+
+    return questionSuggestion.trim () !== ''
+  }, [
+      canPersistGame,
+      reviewCorrectPostId,
+      questionSuggestionEntryMode,
+      selectedSuggestedQuestion,
+      questionSuggestion])
+  const canShowNewQuestionSuggestionButton = useMemo (() => {
+    return questionSuggestionEntryMode === 'search'
+	&& questionSuggestionSearch.trim () !== ''
+	&& searchableSuggestedQuestions.length === 0
+  }, [
+      questionSuggestionEntryMode,
+      questionSuggestionSearch,
+      searchableSuggestedQuestions.length])
   const recentFirstQuestionPenaltyById = useMemo (() => {
     const penalties = new Map<string, number> ()
 
@@ -3494,6 +3588,7 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
       onSuccess: async data => {
 	await queryClient.refetchQueries ({ queryKey: gekanatorKeys.questions () })
 	setQuestionSuggestionCount (data.count)
+	setQuestionSuggestionEntryMode ('search')
 	setQuestionSuggestionSearch ('')
 	setQuestionSuggestionSelectedId (null)
 	setQuestionSuggestion ('')
@@ -3544,6 +3639,7 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
     setSavedGameId (null)
     setLearnedExampleCount (null)
     setGameSeed (createGameSeed ())
+    setQuestionSuggestionEntryMode ('search')
     setQuestionSuggestionSearch ('')
     setQuestionSuggestionSelectedId (null)
     setQuestionSuggestion ('')
@@ -3876,6 +3972,7 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
     setSaved (false)
     setSavedGameId (null)
     setLearnedExampleCount (null)
+    setQuestionSuggestionEntryMode ('search')
     setQuestionSuggestionSearch ('')
     setQuestionSuggestionSelectedId (null)
     setReviewGuessedPostId (guessedPostId)
@@ -3895,6 +3992,7 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
     setSaved (false)
     setSavedGameId (null)
     setLearnedExampleCount (null)
+    setQuestionSuggestionEntryMode ('search')
     setQuestionSuggestionSearch ('')
     setQuestionSuggestionSelectedId (null)
     setSelectingCorrectPost (false)
@@ -3925,6 +4023,12 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
   }
 
   const saveAndReset = () => {
+    if (saveMutation.isError)
+      {
+	reset ()
+	return
+      }
+
     if (!(canPersistGame))
       {
 	reset ()
@@ -3948,11 +4052,7 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
   const submitQuestionSuggestion = () => {
     const questionText = questionSuggestion.trim ()
     const selectedQuestion = selectedSuggestedQuestion
-    if (
-	!(canPersistGame)
-	|| (selectedQuestion === null && !(questionText))
-	|| questionSuggestionMutation.isPending
-    )
+    if (!(canSubmitQuestionSuggestion) || questionSuggestionMutation.isPending)
       return
 
     saveReviewedResult (gekanatorGameId => {
@@ -4092,6 +4192,7 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
     setSaved (false)
     setSavedGameId (null)
     setLearnedExampleCount (null)
+    setQuestionSuggestionEntryMode ('search')
     setQuestionSuggestionSearch ('')
     setQuestionSuggestionSelectedId (null)
     resetExtraQuestionState ()
@@ -4105,6 +4206,7 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 	setSaved (false)
 	setSavedGameId (null)
 	setLearnedExampleCount (null)
+	setQuestionSuggestionEntryMode ('search')
 	setQuestionSuggestionSearch ('')
 	setQuestionSuggestionSelectedId (null)
 	resetExtraQuestionState ()
@@ -4798,62 +4900,101 @@ 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">まず既存質問を探してください。</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>
 		      </div>
-		      <label className="block space-y-2">
-			<span className="font-bold">既存質問を検索</span>
-			<input
-			    value={questionSuggestionSearch}
-			    onChange={ev => {
-			      setQuestionSuggestionSearch (ev.target.value)
-			      setQuestionSuggestionSelectedId (null)
-			    }}
-			    className="w-full rounded border border-yellow-300 bg-white px-3 py-2
-				       dark:border-red-700 dark:bg-red-950"
-			    placeholder="質問文で検索。前方一致を優先して部分一致も出ます。"/>
-		      </label>
-		      {searchableSuggestedQuestions.length > 0 && (
+		      {questionSuggestionEntryMode === 'search'
+		       ? (
+			  <>
+			    <label className="block space-y-2">
+			      <span className="font-bold">既存質問を検索</span>
+			      <input
+				  value={questionSuggestionSearch}
+				  onChange={ev => {
+				    setQuestionSuggestionSearch (ev.target.value)
+				    setQuestionSuggestionSelectedId (null)
+				  }}
+				  className="w-full rounded border border-yellow-300 bg-white px-3 py-2
+					     dark:border-red-700 dark:bg-red-950"
+				  placeholder="質問文で検索。前方一致を優先して部分一致も出ます。"/>
+			    </label>
+			    {searchableSuggestedQuestions.length > 0 && (
+				<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>))}
+				  </div>
+				</div>)}
+			    {selectedSuggestedQuestion && (
+				<p className="text-sm text-neutral-600 dark:text-neutral-300">
+				  既存質問を選択中: {selectedSuggestedQuestion.text}
+				</p>)}
+			    {canShowNewQuestionSuggestionButton && (
+				<div className="space-y-2">
+				  <p className="text-sm text-neutral-600 dark:text-neutral-300">
+				    適切な質問がない場合は新規追加してください。
+				  </p>
+				  <div className="flex flex-wrap gap-2">
+				    <button
+					type="button"
+					className="rounded border border-yellow-300 px-4 py-2
+						   hover:bg-yellow-100 dark:border-red-700
+						   dark:hover:bg-red-900"
+					onClick={() => {
+					  setQuestionSuggestionEntryMode ('new')
+					  setQuestionSuggestionSelectedId (null)
+					  setQuestionSuggestionSearch ('')
+					}}>
+				      新規追加
+				    </button>
+				  </div>
+				</div>)}
+			  </>)
+		       : (
 			  <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>
-				    <div className="text-sm text-neutral-500 dark:text-neutral-400">
-				      {question.kind}
-				    </div>
-				  </button>))}
+			    <div className="font-bold">新規質問</div>
+			    <textarea
+				value={questionSuggestion}
+				onChange={ev => {
+				  setQuestionSuggestion (ev.target.value)
+				  if (ev.target.value.trim () !== '')
+				    setQuestionSuggestionSelectedId (null)
+				}}
+				className="min-h-24 w-full rounded border border-yellow-300
+					   bg-white px-3 py-2 dark:border-red-700
+					   dark:bg-red-950"
+				placeholder="適切な既存質問がない場合だけ新規追加してください。"/>
+			    <div className="flex flex-wrap gap-2">
+			      <button
+				  type="button"
+				  className="rounded border border-neutral-300 px-4 py-2
+					     hover:bg-neutral-100 dark:border-neutral-700
+					     dark:hover:bg-red-900"
+				  onClick={() => {
+				    setQuestionSuggestionEntryMode ('search')
+				    setQuestionSuggestion ('')
+				  }}>
+				既存質問検索へ戻る
+			      </button>
 			    </div>
 			  </div>)}
-		      <div className="space-y-2">
-			<div className="font-bold">新規質問</div>
-			<textarea
-			    value={questionSuggestion}
-			    onChange={ev => {
-			      setQuestionSuggestion (ev.target.value)
-			      if (ev.target.value.trim () !== '')
-				setQuestionSuggestionSelectedId (null)
-			    }}
-			    className="min-h-24 w-full rounded border border-yellow-300
-				       bg-white px-3 py-2 dark:border-red-700
-				       dark:bg-red-950"
-			    placeholder="適切な既存質問がない場合だけ新規追加してください。"/>
-		      </div>
-		      {selectedSuggestedQuestion && (
-			  <p className="text-sm text-neutral-600 dark:text-neutral-300">
-			    既存質問を選択中: {selectedSuggestedQuestion.text}
-			  </p>)}
 		      <label className="block space-y-2">
 			<span className="font-bold">この正解投稿に対する答え</span>
 			<select
@@ -4886,15 +5027,9 @@ const GekanatorPage: FC<{ user: User | null }> = ({ user }) => {
 			    className="rounded border border-yellow-300 px-4 py-2
 				       hover:bg-yellow-100 dark:border-red-700
 				       dark:hover:bg-red-900 disabled:opacity-50"
-			    disabled={
-			      !(canPersistGame)
-			      || reviewCorrectPostId === null
-			      || (
-				  questionSuggestion.trim () === ''
-				  && selectedSuggestedQuestion === null)
-			      || saveMutation.isPending
-			      || questionSuggestionMutation.isPending
-			    }
+			    disabled={!(canSubmitQuestionSuggestion)
+				      || saveMutation.isPending
+				      || questionSuggestionMutation.isPending}
 			    onClick={submitQuestionSuggestion}>
 			  保存
 			</button>