AI: address review on PR #456

frontend/src/components/PostFormTagsArea.test.tsx

@@ -12,36 +12,24 @@ const api = vi.hoisted (() => ({
 vi.mock ('@/lib/api', () => api)
 
 describe ('PostFormTagsArea', () => {
-  it ('replaces the selected token and restores the caret without losing other tags', async () => {
+  it ('updates text and fetches autocomplete for the selected token', async () => {
     const setTags = vi.fn ()
     api.apiGet.mockResolvedValueOnce ([buildTag ({ name: '虹夏', postCount: 3 })])
 
-    const { rerender } = renderWithProviders (
-	<PostFormTagsArea tags="ぼっち 虹 後続" setTags={setTags}/>)
+    renderWithProviders (<PostFormTagsArea tags="虹" setTags={setTags}/>)
 
-    const textarea = screen.getByRole<HTMLTextAreaElement> ('textbox')
+    const textarea = screen.getByRole ('textbox')
     fireEvent.focus (textarea)
-    fireEvent.change (textarea, { target: { value: 'ぼっち 虹な 後続' } })
-    rerender (<PostFormTagsArea tags="ぼっち 虹な 後続" setTags={setTags}/>)
-    fireEvent.select (textarea, { target: { selectionStart: 6, selectionEnd: 6 } })
+    fireEvent.select (textarea, { target: { selectionStart: 1, selectionEnd: 1 } })
+    fireEvent.change (textarea, { target: { value: '虹夏' } })
 
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenCalledWith (
-	  '/tags/autocomplete', {
-	      locale: 'ja', params: { q: '虹な', nico: '0' },
-	      signal: expect.any (AbortSignal) })
+          '/tags/autocomplete',
+          { locale: 'ja', params: { q: '虹', nico: '0' },
+	    signal: expect.any (AbortSignal) },
+      )
     })
-    expect (setTags).toHaveBeenCalledWith ('ぼっち 虹な 後続')
-
-    fireEvent.mouseDown (await screen.findByText ('虹夏'))
-    expect (setTags).toHaveBeenLastCalledWith ('ぼっち 虹夏  後続')
-    rerender (<PostFormTagsArea tags="ぼっち 虹夏  後続" setTags={setTags}/>)
-
-    await waitFor (() => {
-      expect (textarea).toHaveFocus ()
-      expect (textarea.selectionStart).toBe (7)
-      expect (textarea.selectionEnd).toBe (7)
-    })
-    expect (screen.queryByText ('虹夏')).not.toBeInTheDocument ()
+    expect (setTags).toHaveBeenCalledWith ('虹夏')
   })
 })

frontend/src/components/PostFormTagsArea.tsx

@@ -1,10 +1,13 @@
-import { useRef, useState } from 'react'
+// TODO: TagSearch と共通化する．
 
-import { useTagAutocomplete } from '@/lib/useTagAutocomplete'
+import { useEffect, useRef, useState } from 'react'
+
+import { useLocale } from '@/lib/useLocale'
 import { useUITranslation } from '@/lib/useUITranslation'
 import TagSearchBox from '@/components/TagSearchBox'
 import FormField from '@/components/common/FormField'
 import TextArea from '@/components/common/TextArea'
+import { apiGet } from '@/lib/api'
 
 import type { ComponentPropsWithoutRef, FC, ReactNode, SyntheticEvent } from 'react'
 
@@ -38,13 +41,24 @@ type Props = Omit<ComponentPropsWithoutRef<'textarea'>, 'value' | 'onChange' | '
 
 const PostFormTagsArea: FC<Props> = ({ tags, setTags, errors, ...rest }) => {
   const { label } = useUITranslation ('navigation')
+  const locale = useLocale ()
   const ref = useRef<HTMLTextAreaElement> (null)
 
   const [bounds, setBounds] = useState<{ start: number; end: number }> ({ start: 0, end: 0 })
   const [focused, setFocused] = useState (false)
+  const [request, setRequest] = useState ({ query: '' })
+  const [result, setResult] = useState<{
+      locale: string
+      request: { query: string }
+      tags: Tag[] }> ({ locale, request, tags: [] })
   const currentToken = getTokenAt (tags, Math.min (bounds.start, tags.length)).token
+  const suggestions = (result.locale === locale && result.request === request
+      && request.query === currentToken) ? result.tags : []
+  const [suggestionsVsbl, setSuggestionsVsbl] = useState (false)
 
   const handleTagSelect = (tag: Tag) => {
+    setSuggestionsVsbl (false)
+    setRequest ({ query: '' })
     const textarea = ref.current!
     const newValue = replaceToken (tags, bounds.start, bounds.end, tag.name + ' ')
     setTags (newValue)
@@ -56,18 +70,52 @@ const PostFormTagsArea: FC<Props> = ({ tags, setTags, errors, ...rest }) => {
     })
   }
 
-  const { inputProps, suggestionProps, requestSuggestions } =
-      useTagAutocomplete ({ token: currentToken, onSelect: handleTagSelect })
-
   const recompute = (pos: number, v: string = tags) => {
     const { start, end, token } = getTokenAt (v, pos)
-    requestSuggestions (token)
+    setRequest ({ query: token })
+    setSuggestionsVsbl (token.trim () !== '')
     if (!(token.trim ()))
-      return
+      {
+	setSuggestionsVsbl (false)
+	return
+      }
 
     setBounds ({ start, end })
   }
 
+  useEffect (() => {
+    if (request.query.trim () === '')
+      return
+    const controller = new AbortController ()
+    let active = true
+    void (async () => {
+      try
+      {
+	const tags = await apiGet<Tag[]> ('/tags/autocomplete', {
+	    locale, signal: controller.signal, params: { q: request.query, nico: '0' } })
+	if (active)
+	{
+	  setResult ({ locale, request,
+	      tags: tags.filter (tag => tag.postCount > 0) })
+	}
+      }
+      catch
+      {
+	if (active)
+	  setResult ({ locale, request, tags: [] })
+      }
+    }) ()
+    return () => {
+      active = false
+      controller.abort ()
+    }
+  }, [request, locale])
+
+  useEffect (() => {
+    setSuggestionsVsbl (false)
+    setRequest ({ query: '' })
+  }, [locale])
+
   return (
       <FormField className="relative w-full" label={label ('tags')} messages={errors}>
 	{({ describedBy, invalid }) => (
@@ -86,10 +134,15 @@ const PostFormTagsArea: FC<Props> = ({ tags, setTags, errors, ...rest }) => {
 		  onFocus={() => setFocused (true)}
 		  onBlur={() => {
 		    setFocused (false)
-		    inputProps.onBlur ()
+		    setSuggestionsVsbl (false)
 		  }}/>
 	      {focused && (
-		  <TagSearchBox {...suggestionProps}/>)}
+		  <TagSearchBox
+		      suggestions={suggestionsVsbl && suggestions.length > 0
+				   ? suggestions
+				   : [] as Tag[]}
+		      activeIndex={-1}
+		      onSelect={handleTagSelect}/>)}
 	    </>)}
       </FormField>)
 }

frontend/src/components/TagSearch.test.tsx

@@ -1,4 +1,4 @@
-import { act, fireEvent, screen } from '@testing-library/react'
+import { fireEvent, screen } from '@testing-library/react'
 import userEvent from '@testing-library/user-event'
 import { useLocation } from 'react-router-dom'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
@@ -8,8 +8,6 @@ import * as api from '@/lib/api'
 import { buildTag } from '@/test/factories'
 import { renderWithProviders } from '@/test/render'
 
-import type { Tag } from '@/types'
-
 
 const LocationOutput = () => {
   const location = useLocation ()
@@ -119,39 +117,4 @@ describe ('TagSearch', () => {
     expect (screen.getByTestId ('location')).toHaveTextContent ('/ja/posts?page=3')
     expect (screen.queryByText ('虹夏')).not.toBeInTheDocument ()
   })
-
-  it ('aborts obsolete requests and ignores their late suggestions', async () => {
-    const responses: ((tags: Tag[]) => void)[] = []
-    vi.mocked (api.apiGet).mockImplementation (() => new Promise<Tag[]> (resolve => {
-      responses.push (resolve)
-    }))
-    const { unmount } = renderSearch ()
-    const input = screen.getByRole ('textbox')
-
-    fireEvent.change (input, { target: { value: '虹' } })
-    const previousSignal = vi.mocked (api.apiGet).mock.calls.at (-1)?.[1]?.signal
-    expect (previousSignal).toBeInstanceOf (AbortSignal)
-    expect (previousSignal?.aborted).toBe (false)
-
-    fireEvent.change (input, { target: { value: 'ぼ' } })
-    expect (previousSignal?.aborted).toBe (true)
-    expect (api.apiGet).toHaveBeenLastCalledWith ('/tags/autocomplete', {
-	locale: 'ja', params: { q: 'ぼ', nico: '1' },
-	signal: expect.any (AbortSignal) })
-    const currentSignal = vi.mocked (api.apiGet).mock.calls.at (-1)?.[1]?.signal
-
-    await act (async () => {
-      responses[1] ([buildTag ({ name: 'ぼっち' })])
-    })
-    expect (screen.getByText ('ぼっち')).toBeInTheDocument ()
-
-    await act (async () => {
-      responses[0] ([buildTag ({ name: '虹夏' })])
-    })
-    expect (screen.queryByText ('虹夏')).not.toBeInTheDocument ()
-    expect (screen.getByText ('ぼっち')).toBeInTheDocument ()
-
-    unmount ()
-    expect (currentSignal?.aborted).toBe (true)
-  })
 })

frontend/src/components/TagSearch.tsx

@@ -1,46 +1,82 @@
-import { useEffect, useState } from 'react'
+// TODO: タグ入力系すべてに同様の処理あるため共通化する．
+
+import { useEffect, useRef, useState } from 'react'
 import { useLocation } from 'react-router-dom'
 
-import TagSearchBox from '@/components/TagSearchBox'
-import { useLocaleNavigate } from '@/lib/useLocale'
-import { useTagAutocomplete } from '@/lib/useTagAutocomplete'
+import { useLocale, useLocaleNavigate } from '@/lib/useLocale'
 import { useUITranslation } from '@/lib/useUITranslation'
+import { apiGet } from '@/lib/api'
 import { inputClass } from '@/lib/utils'
 
-import type { ChangeEvent, FC, FormEvent } from 'react'
+import TagSearchBox from './TagSearchBox'
+
+import type { ChangeEvent, FC, FormEvent, KeyboardEvent } from 'react'
 
 import type { Tag } from '@/types'
 
 
 const TagSearch: FC = () => {
   const { message } = useUITranslation ('shared')
+  const locale = useLocale ()
   const location = useLocation ()
   const navigate = useLocaleNavigate ()
+  const compositionFlgRef = useRef (false)
+
+  const [activeIndex, setActiveIndex] = useState (-1)
   const [search, setSearch] = useState ('')
+  const [request, setRequest] = useState ({ query: '' })
+  const [result, setResult] = useState<{
+      locale: string
+      request: { query: string }
+      tags: Tag[] }> ({ locale, request, tags: [] })
+  const suggestions = result.locale === locale && result.request === request
+      ? result.tags : []
+  const [suggestionsVsbl, setSuggestionsVsbl] = useState (false)
 
-  const handleTagSelect = (tag: Tag) => {
-    const parts = search.split (' ')
-    parts[parts.length - 1] = (
-	(parts[parts.length - 1].slice (0, 4).toLowerCase () === 'not:')
-	? ('not:' + tag.name)
-	: tag.name)
-    setSearch (parts.join (' ') + ' ')
-  }
-
-  const { inputProps, suggestionProps, requestSuggestions,
-	  clearSuggestions, compositionFlgRef } = useTagAutocomplete ({
-      token: search.trim ().split (' ').at (-1) ?? '',
-      nicoFlg: true,
-      onSelect: handleTagSelect })
-
-  const whenChanged = (event: ChangeEvent<HTMLInputElement>) => {
-    const value = event.target.value
+  const whenChanged = (ev: ChangeEvent<HTMLInputElement>) => {
+    const value = ev.target.value
+    const query = value.trim ().split (' ').at (-1) ?? ''
     setSearch (value)
-    requestSuggestions (value.trim ().split (' ').at (-1) ?? '')
+    setRequest ({ query })
+    setActiveIndex (-1)
+    setSuggestionsVsbl (query !== '')
   }
 
-  const handleSubmit = (event: FormEvent<HTMLFormElement>) => {
-    event.preventDefault ()
+  useEffect (() => {
+    if (request.query === '')
+      return
+    const controller = new AbortController ()
+    let active = true
+    void (async () => {
+      try
+      {
+	const tags = await apiGet<Tag[]> ('/tags/autocomplete', {
+	    locale, signal: controller.signal, params: { q: request.query } })
+	if (active)
+	{
+	  setResult ({ locale, request,
+	      tags: tags.filter (tag => tag.postCount > 0) })
+	}
+      }
+      catch
+      {
+	if (active)
+	  setResult ({ locale, request, tags: [] })
+      }
+    }) ()
+    return () => {
+      active = false
+      controller.abort ()
+    }
+  }, [request, locale])
+
+  useEffect (() => {
+    setActiveIndex (-1)
+    setSuggestionsVsbl (false)
+  }, [locale])
+
+  const handleSubmit = (ev: FormEvent<HTMLFormElement>) => {
+    ev.preventDefault ()
     if (compositionFlgRef.current)
       return
 
@@ -53,7 +89,61 @@ const TagSearch: FC = () => {
 		       .filter (t => t !== 'type:or')
 		       .join (' '),
 	    match })).toString () }`)
-    clearSuggestions ()
+    setSuggestionsVsbl (false)
+    setRequest ({ query: '' })
+  }
+
+  const handleKeyDown = (ev: KeyboardEvent<HTMLInputElement>) => {
+    if (compositionFlgRef.current
+	|| ev.nativeEvent.isComposing
+	|| ev.nativeEvent.keyCode === 229)
+    {
+      if (ev.key === 'Enter')
+	ev.preventDefault ()
+      return
+    }
+
+    switch (ev.key)
+    {
+    case 'ArrowDown':
+      ev.preventDefault ()
+      setActiveIndex (i => Math.min (i + 1, suggestions.length - 1))
+      setSuggestionsVsbl (true)
+      break
+
+    case 'ArrowUp':
+      ev.preventDefault ()
+      setActiveIndex (i => Math.max (i - 1, -1))
+      setSuggestionsVsbl (true)
+      break
+
+    case 'Enter':
+      {
+	const selected = suggestionsVsbl ? suggestions[activeIndex] : null
+	if (selected == null)
+	  break
+	ev.preventDefault ()
+	handleTagSelect (selected)
+      }
+      break
+
+    case 'Escape':
+      ev.preventDefault ()
+      setSuggestionsVsbl (false)
+      break
+    }
+  }
+
+  const handleTagSelect = (tag: Tag) => {
+    const parts = search.split (' ')
+    parts[parts.length - 1] = (
+	(parts[parts.length - 1].slice(0, 4).toLowerCase () === 'not:')
+	? ('not:' + tag.name)
+	: tag.name)
+    setSearch (parts.join (' ') + ' ')
+    setRequest ({ query: '' })
+    setSuggestionsVsbl (false)
+    setActiveIndex (-1)
   }
 
   useEffect (() => {
@@ -61,21 +151,33 @@ const TagSearch: FC = () => {
     const anyFlg = query.get ('match') === 'any'
     const tagsQuery = `${ query.get ('tags') ?? '' }${ anyFlg ? ' type:or' : '' }`
     setSearch (tagsQuery)
-    clearSuggestions ()
-  }, [location.search, clearSuggestions])
+    setRequest ({ query: '' })
+    setActiveIndex (-1)
+    setSuggestionsVsbl (false)
+  }, [location.search])
 
   return (
       <form onSubmit={handleSubmit} className="relative w-full">
 	<input type="text"
-	       {...inputProps}
 	       enterKeyHint="search"
 	       data-shortcut-focus-search="true"
 	       placeholder={message ('labels.tagSearch').text}
 	       value={search}
 	       onChange={whenChanged}
+	       onFocus={() => setSuggestionsVsbl (true)}
+	       onBlur={() => setSuggestionsVsbl (false)}
+	       onKeyDown={handleKeyDown}
+	       onCompositionStart={() => {
+		 compositionFlgRef.current = true
+	       }}
+	       onCompositionEnd={() => {
+		 compositionFlgRef.current = false
+	       }}
 	       className={inputClass (false,
 				      'px-3 py-2 dark:border-gray-600 dark:bg-gray-800 dark:text-white')}/>
-	<TagSearchBox {...suggestionProps}/>
+	<TagSearchBox suggestions={suggestionsVsbl && suggestions.length ? suggestions : [] as Tag[]}
+		      activeIndex={activeIndex}
+		      onSelect={handleTagSelect}/>
       </form>)
 }
 

frontend/src/components/common/TagInput.test.tsx

@@ -1,4 +1,4 @@
-import { act, fireEvent, screen, waitFor } from '@testing-library/react'
+import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import TagInput from '@/components/common/TagInput'
@@ -20,20 +20,18 @@ describe ('TagInput', () => {
     const setValue = vi.fn ()
     api.apiGet.mockResolvedValueOnce ([buildTag ({ name: '虹夏', postCount: 2 })])
 
-    const { rerender } = render (
-	<TagInput value="ぼっち 虹" setValue={setValue}/>)
+    render (<TagInput value="ぼっち 虹" setValue={setValue}/>)
 
     fireEvent.change (screen.getByRole ('textbox'), { target: { value: 'ぼっち 虹夏' } })
-    rerender (<TagInput value="ぼっち 虹夏" setValue={setValue}/>)
 
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenCalledWith (
-	  '/tags/autocomplete', {
-	      locale: 'ja', params: { q: '虹夏', nico: '0' },
-	      signal: expect.any (AbortSignal) })
+          '/tags/autocomplete',
+          { locale: 'ja', params: { q: '虹夏', nico: '0' },
+	    signal: expect.any (AbortSignal) },
+      )
     })
     expect (setValue).toHaveBeenCalledWith ('ぼっち 虹夏')
-    expect (await screen.findByText ('虹夏')).toBeInTheDocument ()
   })
 
   it ('does not fetch when the last token is blank', () => {
@@ -56,51 +54,10 @@ describe ('TagInput', () => {
 
     await waitFor (() => {
       expect (api.apiGet).toHaveBeenCalledWith (
-	  '/tags/autocomplete', {
-	      locale: 'ja', params: { q: '虹夏', nico: '1' },
-	      signal: expect.any (AbortSignal) })
+          '/tags/autocomplete',
+          { locale: 'ja', params: { q: '虹夏', nico: '1' },
+	    signal: expect.any (AbortSignal) },
+      )
     })
   })
-
-  it ('preserves negation and blocks suggestion selection during composition', async () => {
-    const setValue = vi.fn ()
-    api.apiGet.mockResolvedValueOnce ([buildTag ({ name: '虹夏' })])
-    const { rerender } = render (<TagInput value="" setValue={setValue}/>)
-    const input = screen.getByRole ('textbox')
-
-    fireEvent.change (input, { target: { value: 'ぼっち NOT:虹' } })
-    rerender (<TagInput value="ぼっち NOT:虹" setValue={setValue}/>)
-    await screen.findByText ('虹夏')
-    expect (api.apiGet).toHaveBeenLastCalledWith (
-	'/tags/autocomplete', {
-	    locale: 'ja', params: { q: '虹', nico: '0' },
-	    signal: expect.any (AbortSignal) })
-
-    fireEvent.keyDown (input, { key: 'ArrowDown' })
-    fireEvent.compositionStart (input)
-    expect (fireEvent.keyDown (input, { key: 'Enter' })).toBe (false)
-    expect (setValue).toHaveBeenCalledTimes (1)
-
-    fireEvent.compositionEnd (input)
-    fireEvent.keyDown (input, { key: 'Enter' })
-
-    expect (setValue).toHaveBeenLastCalledWith ('ぼっち not:虹夏 ')
-    expect (screen.queryByText ('虹夏')).not.toBeInTheDocument ()
-  })
-
-  it.each ([false, true]) ('includes unused tags only with includeUnused=%s', async unusedFlg => {
-    const tag = buildTag ({ name: '虹夏', postCount: 0 })
-    const response = Promise.resolve ([tag])
-    api.apiGet.mockReturnValueOnce (response)
-    const props = { setValue: vi.fn (), includeUnused: unusedFlg }
-    const { rerender } = render (<TagInput {...props} value=""/>)
-
-    fireEvent.change (screen.getByRole ('textbox'), { target: { value: '虹' } })
-    rerender (<TagInput {...props} value="虹"/>)
-    await act (async () => {
-      await response
-    })
-
-    expect (screen.queryByText ('虹夏') != null).toBe (unusedFlg)
-  })
 })

frontend/src/components/common/TagInput.tsx

@@ -1,8 +1,11 @@
+import { useEffect, useState } from 'react'
+
+import { useLocale } from '@/lib/useLocale'
 import TagSearchBox from '@/components/TagSearchBox'
-import { useTagAutocomplete } from '@/lib/useTagAutocomplete'
+import { apiGet } from '@/lib/api'
 import { inputClass } from '@/lib/utils'
 
-import type { FC, ChangeEvent } from 'react'
+import type { FC, ChangeEvent, KeyboardEvent } from 'react'
 
 import type { Tag } from '@/types'
 
@@ -16,39 +19,136 @@ type Props = {
     setValue:      (value: string) => void }
 
 
-const TagInput: FC<Props> = (
-    { includeNico: nicoFlg = false,
-      includeUnused: unusedFlg = false,
-      describedBy, invalid, value, setValue },
-) => {
+const TagInput: FC<Props> = ({
+    includeNico = false,
+    includeUnused = false,
+    describedBy,
+    invalid,
+    value,
+    setValue,
+}) => {
+  const locale = useLocale ()
+  const [activeIndex, setActiveIndex] = useState (-1)
+  const [request, setRequest] = useState ({ query: '' })
+  const [result, setResult] = useState<{
+      locale: string
+      includeNico: boolean
+      request: { query: string }
+      tags: Tag[] }> ({ locale, includeNico, request, tags: [] })
+  const suggestions = (result.locale === locale && result.includeNico === includeNico
+      && result.request === request
+      && request.query === value.trim ().split (' ').at (-1)) ? result.tags : []
+  const [suggestionsVsbl, setSuggestionsVsbl] = useState (false)
+
+  // TODO: TagSearch からのコピペのため，共通化を考へる．
+  const whenChanged = (ev: ChangeEvent<HTMLInputElement>) => {
+    setValue (ev.target.value)
+    const query = ev.target.value.trim ().split (' ').at (-1) ?? ''
+    setRequest ({ query })
+    setActiveIndex (-1)
+    setSuggestionsVsbl (query !== '')
+  }
+
+  useEffect (() => {
+    if (request.query === '')
+      return
+    const controller = new AbortController ()
+    let active = true
+    void (async () => {
+      try
+      {
+	const tags = await apiGet<Tag[]> ('/tags/autocomplete', {
+	    locale, signal: controller.signal,
+	    params: { q: request.query.replace (/^not:/i, ''), nico: includeNico ? '1' : '0' } })
+	if (active)
+	{
+	  setResult ({ locale, includeNico, request,
+	      tags: includeUnused ? tags : tags.filter (tag => tag.postCount > 0) })
+	}
+      }
+      catch
+      {
+	if (active)
+	  setResult ({ locale, includeNico, request, tags: [] })
+      }
+    }) ()
+    return () => {
+      active = false
+      controller.abort ()
+    }
+  }, [request, locale, includeNico, includeUnused])
+
+  useEffect (() => {
+    setActiveIndex (-1)
+    setSuggestionsVsbl (false)
+    setRequest ({ query: '' })
+  }, [locale, includeNico])
+
+  // TODO: TagSearch からのコピペのため，共通化を考へる．
   const handleTagSelect = (tag: Tag) => {
     const parts = value?.split (' ')
     const negative = /^not:/i.test (parts[parts.length - 1])
     parts[parts.length - 1] = `${negative ? 'not:' : ''}${tag.name}`
     setValue (parts.join (' ') + ' ')
+    setRequest ({ query: '' })
+    setActiveIndex (-1)
   }
 
-  const { inputProps, suggestionProps, requestSuggestions } =
-      useTagAutocomplete ({ token: value.trim ().split (' ').at (-1) ?? '',
-			    nicoFlg, unusedFlg, onSelect: handleTagSelect })
+  // TODO: TagSearch からのコピペのため，共通化を考へる．
+  const handleKeyDown = (ev: KeyboardEvent<HTMLInputElement>) => {
+    switch (ev.key)
+    {
+    case 'ArrowDown':
+      ev.preventDefault ()
+      setActiveIndex (i => Math.min (i + 1, suggestions.length - 1))
+      setSuggestionsVsbl (true)
+      break
 
-  const whenChanged = (event: ChangeEvent<HTMLInputElement>) => {
-    setValue (event.target.value)
-    const token = event.target.value.trim ().split (' ').at (-1) ?? ''
-    requestSuggestions (token, token.replace (/^not:/i, ''))
+    case 'ArrowUp':
+      ev.preventDefault ()
+      setActiveIndex (i => Math.max (i - 1, -1))
+      setSuggestionsVsbl (true)
+      break
+
+    case 'Enter':
+      if (activeIndex < 0)
+	break
+      {
+	ev.preventDefault ()
+	const selected = suggestions[activeIndex]
+	if (selected)
+	  handleTagSelect (selected)
+      }
+      break
+
+    case 'Escape':
+      ev.preventDefault ()
+      setSuggestionsVsbl (false)
+      break
+    }
+    if (ev.key === 'Enter' && (!(suggestionsVsbl) || activeIndex < 0))
+      {
+	setSuggestionsVsbl (false)
+      }
   }
 
   return (
       <div className="relative">
 	<input
-	    {...inputProps}
 	    type="text"
 	    aria-describedby={describedBy}
 	    aria-invalid={invalid}
 	    value={value}
 	    onChange={whenChanged}
+	    onFocus={() => setSuggestionsVsbl (true)}
+	    onBlur={() => setSuggestionsVsbl (false)}
+	    onKeyDown={handleKeyDown}
 	    className={inputClass (invalid)}/>
-	<TagSearchBox {...suggestionProps}/>
+	<TagSearchBox
+	    suggestions={
+		suggestionsVsbl && suggestions.length > 0 ? suggestions : [] as Tag[]}
+	    activeIndex={activeIndex}
+	    onSelect={handleTagSelect}/>
       </div>)
 }
 

frontend/src/components/layout/SidebarComponent.test.tsx

@@ -70,6 +70,16 @@ describe ('SidebarComponent', () => {
     vi.spyOn (HTMLElement.prototype, 'hasPointerCapture').mockReturnValue (true)
   })
 
+  it ('limits sidebar scrolling to desktop to avoid clipping mobile suggestions', () => {
+    renderSidebar ()
+
+    // jsdom has no layout; guard the responsive classes responsible for clipping.
+    const sidebar = screen.getByText ('Sidebar body')
+
+    expect (sidebar).not.toHaveClass ('overflow-y-auto')
+    expect (sidebar).toHaveClass ('md:overflow-y-auto')
+  })
+
   it ('uses maxWidth without applying the container main-width reserve twice', async () => {
     localStorage.setItem ('sidebar:test-sidebar:left:width', '700')
     const onWidthChange = vi.fn ()

frontend/src/components/layout/SidebarComponent.tsx

@@ -339,7 +339,7 @@ const SidebarComponent: FC<Props> = ({
 	  </style>
 	</Helmet>
 
-	<div className="h-full overflow-y-auto p-4 sidebar">
+	<div className="h-full md:overflow-y-auto p-4 sidebar">
 	  {children}
 	</div>
 

frontend/src/lib/tags.ts

@@ -11,17 +11,6 @@ import type { Deerjikist,
 	      TagVersion } from '@/types'
 
 
-export const fetchTagAutocomplete = async (
-    query: string,
-    nicoFlg: boolean,
-    locale: LocaleCode,
-    signal: AbortSignal,
-): Promise<Tag[]> =>
-    await apiGet ('/tags/autocomplete', {
-	locale, signal,
-	params: { q: query, nico: nicoFlg ? '1' : '0' } })
-
-
 export const fetchTags = async (
     { post, name, category, postCountGTE, postCountLTE, createdFrom, createdTo,
       updatedFrom, updatedTo, deprecated,

frontend/src/lib/useTagAutocomplete.ts

@@ -1,142 +0,0 @@
-import { useCallback, useEffect, useRef, useState } from 'react'
-
-import { fetchTagAutocomplete } from '@/lib/tags'
-import { useLocale } from '@/lib/useLocale'
-
-import type { KeyboardEvent } from 'react'
-
-import type { Tag } from '@/types'
-
-
-export const useTagAutocomplete = (
-    { token, onSelect, nicoFlg = false, unusedFlg = false }: {
-	token: string
-	onSelect: (tag: Tag) => void
-	nicoFlg?: boolean
-	unusedFlg?: boolean },
-) => {
-  const locale = useLocale ()
-  const compositionFlgRef = useRef (false)
-  const [activeIndex, setActiveIndex] = useState (-1)
-  const [visible, setVisible] = useState (false)
-  const [request, setRequest] = useState ({ token: '', query: '' })
-  const [result, setResult] = useState<{
-      locale: string
-      nicoFlg: boolean
-      unusedFlg: boolean
-      request: { token: string; query: string }
-      tags: Tag[] }> ({ locale, nicoFlg, unusedFlg, request, tags: [] })
-  const suggestions = (result.locale === locale && result.nicoFlg === nicoFlg
-      && result.unusedFlg === unusedFlg && result.request === request
-      && request.token === token) ? result.tags : []
-
-  const requestSuggestions = (token: string, query: string = token) => {
-    setRequest ({ token, query })
-    setActiveIndex (-1)
-    setVisible (token.trim () !== '')
-  }
-
-  const clearSuggestions = useCallback (() => {
-    setRequest ({ token: '', query: '' })
-    setActiveIndex (-1)
-    setVisible (false)
-  }, [])
-
-  useEffect (() => {
-    if (request.token.trim () === '')
-      return
-    const controller = new AbortController ()
-    let active = true
-    void (async () => {
-      try
-      {
-	const tags = await fetchTagAutocomplete (
-	    request.query, nicoFlg, locale, controller.signal)
-	if (active)
-	{
-	  setResult ({ locale, nicoFlg, unusedFlg, request,
-	      tags: unusedFlg ? tags : tags.filter (tag => tag.postCount > 0) })
-	}
-      }
-      catch
-      {
-	if (active)
-	  setResult ({ locale, nicoFlg, unusedFlg, request, tags: [] })
-      }
-    }) ()
-    return () => {
-      active = false
-      controller.abort ()
-    }
-  }, [request, locale, nicoFlg, unusedFlg])
-
-  useEffect (() => {
-    clearSuggestions ()
-  }, [locale, nicoFlg, clearSuggestions])
-
-  const handleTagSelect = (tag: Tag) => {
-    clearSuggestions ()
-    onSelect (tag)
-  }
-
-  const handleKeyDown = (event: KeyboardEvent<HTMLInputElement>) => {
-    if (compositionFlgRef.current
-	|| event.nativeEvent.isComposing
-	|| event.nativeEvent.keyCode === 229)
-    {
-      if (event.key === 'Enter')
-	event.preventDefault ()
-      return
-    }
-
-    switch (event.key)
-    {
-    case 'ArrowDown':
-      event.preventDefault ()
-      setActiveIndex (index => Math.min (index + 1, suggestions.length - 1))
-      setVisible (true)
-      break
-
-    case 'ArrowUp':
-      event.preventDefault ()
-      setActiveIndex (index => Math.max (index - 1, -1))
-      setVisible (true)
-      break
-
-    case 'Enter':
-      {
-	const selected = visible ? suggestions[activeIndex] : null
-	if (selected == null)
-	{
-	  setVisible (false)
-	  break
-	}
-	event.preventDefault ()
-	handleTagSelect (selected)
-      }
-      break
-
-    case 'Escape':
-      event.preventDefault ()
-      setVisible (false)
-      break
-    }
-  }
-
-  return {
-      requestSuggestions, clearSuggestions, compositionFlgRef,
-      inputProps: {
-	  onFocus: () => setVisible (true),
-	  onBlur: () => setVisible (false),
-	  onKeyDown: handleKeyDown,
-	  onCompositionStart: () => {
-	    compositionFlgRef.current = true
-	  },
-	  onCompositionEnd: () => {
-	    compositionFlgRef.current = false
-	  } },
-      suggestionProps: {
-	  suggestions: visible ? suggestions : [],
-	  activeIndex,
-	  onSelect: handleTagSelect } }
-}