Merge commit 'ecbf75a5e70f662b6420375140cf12eb6bac7860' into worktree/retarget-pr885-20260729

# Conflicts:
#	docs/development.i18n.yaml
#	packages/client/ui-conversation/src/client/chat/MessageItem.tsx
#	packages/client/ui-primitives/src/markdown/CodeBlock.tsx
#	scripts/snapshots/translation-prompt-v4/request-response.expected.json

packages/client/ui-primitives/src/markdown/CodeBlock.tsx

@@ -6,6 +6,7 @@
 
 import { useCallback, useMemo, useRef, useState } from 'react'
 import clsx from 'clsx'
+import { writeClipboard } from '../clipboard.ts'
 import { highlightToHtml } from './highlight.ts'
 import css from './CodeBlock.module.css'
 
@@ -18,45 +19,6 @@ export interface CodeBlockProps {
   className?: string | undefined
 }
 
-/** @returns true only when the host accepted the write. */
-async function writeClipboard(text: string): Promise<boolean> {
-  // lib.dom types clipboard non-optional, but insecure contexts omit it —
-  // that runtime gap is exactly what this guard detects.
-  /* oxlint-disable-next-line typescript/no-unnecessary-condition */
-  if (navigator.clipboard?.writeText) {
-    try {
-      await navigator.clipboard.writeText(text)
-      return true
-    } catch {
-      // Denied permissions / iframe policy — do not claim success.
-      return false
-    }
-  }
-  // jsdom and older hosts: best-effort execCommand path when present.
-  // execCommand('copy') is the only clipboard fallback where the async API
-  // is missing; deprecated but deliberately retained.
-  /* oxlint-disable typescript/no-deprecated */
-  const exec = typeof document.execCommand === 'function'
-    ? document.execCommand.bind(document)
-    : undefined
-  if (exec === undefined) return false
-  const el = document.createElement('textarea')
-  el.value = text
-  el.setAttribute('readonly', '')
-  el.style.position = 'fixed'
-  el.style.left = '-9999px'
-  document.body.appendChild(el)
-  el.select()
-  try {
-    return exec('copy')
-  } catch {
-    return false
-  } finally {
-    el.remove()
-  }
-  /* oxlint-enable typescript/no-deprecated */
-}
-
 export function CodeBlock({ code, lang, className }: CodeBlockProps) {
   const trimmed = code.endsWith('\n') ? code.slice(0, -1) : code
   const html = useMemo(() => highlightToHtml(trimmed, lang), [trimmed, lang])