chore(lint): clear the semantic .tsx backlog

Hand fixes for the findings --fix cannot touch, mirroring the fixes
already applied on the fe-docs feature branch (same file, same shape)
so its eventual rebase resolves cleanly:

- restore the return the no-confusing-void-expression autofix ate in
  useAbsentSnapshot (typed S | undefined; hook call kept for hook-order
  stability, undefined returned explicitly);
- re-type DOM queries the no-unnecessary-type-assertion autofix broke:
  getByRole<HTMLButtonElement>(...) generics instead of the removed
  as-casts (the eslint program and the client tsconfig aggregate
  disagree about these casts; the generic form satisfies both);
- justified eslint-disable for the deliberate legacy paths: keyCode 229
  IME-composition detection, execCommand clipboard fallbacks, lib.dom
  clipboard optionality, and the any-typed Reflect.get/this probes in
  test fakes;
- drop the dead react/no-danger directive (eslint-plugin-react is not
  loaded, so the rule never applied) keeping its shiki rationale;
- delete the tautological 'Z' comparison and the renameTarget null
  check already implied by renameBlocked;
- css-module non-null assertions replaced by type widening
  (Button className, TAG_CLASS Record) per the established pattern;
- misc: max-len comment wraps, void generic drop in the deferred test
  helper, unused type imports, floating selectWorkspace promises voided,
  member-delimiter newlines in inline type literals.

packages/client/ui-conversation/src/client/chat/ChatView.tsx

@@ -86,7 +86,8 @@ const CallRow = memo(function CallRow({ renderSlot, callId, toolName, block, seq
   seq: number
   onOpenDetails: OpenDetails
   selected: boolean
-  /** `run_code` sub-dispatches in dispatch order (reference-stable per parent; running entries settle in place); undefined for ordinary calls. */
+  /** `run_code` sub-dispatches in dispatch order (reference-stable per
+   *  parent; running entries settle in place); undefined for ordinary calls. */
   subCalls?: readonly CodeSubCall[] | undefined
   /** The store's selected callId, matched against sub-rows (undefined when no sub-row here is selected). */
   selectedCallId?: string | undefined
@@ -162,7 +163,10 @@ function StreamingTail({ useSession, onGrow }: {
   return <AssistantMarkdown blocks={partial.blocks} streaming />
 }
 
-/** The chat view slot entry: pure component over the composed props (tool rows render through the declared keyed hole's renderSlot share). */
+/**
+ * The chat view slot entry: pure component over the composed props (tool rows
+ * render through the declared keyed hole's renderSlot share).
+ */
 export function ChatView({ useSession, useStore, renderSlot, openDetails, loadOlder }: ChatViewSlotProps) {
   const nodes = useSession(s => s.nodes)
   const runningCalls = useSession(s => s.runningCalls)

packages/client/ui-conversation/src/client/chat/MessageItem.tsx

@@ -32,6 +32,9 @@ function contentText(content: readonly unknown[]): { text: string; rest: unknown
 
 /** Best-effort clipboard write; rejections stay swallowed (no success chrome). */
 async function writeClipboard(text: string): Promise<void> {
+  // lib.dom types clipboard non-optional, but insecure contexts omit it —
+  // that runtime gap is exactly what this guard detects.
+  /* eslint-disable-next-line @typescript-eslint/no-unnecessary-condition */
   if (navigator.clipboard?.writeText) {
     try {
       await navigator.clipboard.writeText(text)
@@ -40,6 +43,9 @@ async function writeClipboard(text: string): Promise<void> {
     }
     return
   }
+  // execCommand('copy') is the only clipboard fallback where the async API
+  // is missing (insecure contexts); deprecated but deliberately retained.
+  /* eslint-disable @typescript-eslint/no-deprecated */
   const exec = typeof document.execCommand === 'function'
     ? document.execCommand.bind(document)
     : undefined
@@ -56,6 +62,7 @@ async function writeClipboard(text: string): Promise<void> {
   } catch {
     // Clipboard unavailable; the button stays idle.
   }
+  /* eslint-enable @typescript-eslint/no-deprecated */
   el.remove()
 }
 

packages/client/ui-conversation/src/client/skeleton/ConversationSession.tsx

@@ -41,8 +41,8 @@ export function ConversationSession({
     if (inputState.draft === '' && storedDraft !== '') inputActions.setDraft(storedDraft)
     const unmirror = bindDraftMirror(actions.setDraft)
     return () => { unmirror() }
-    // Mount-only: later store writes come from the machine mirror.
-    // eslint-disable-next-line react-hooks/exhaustive-deps
+    // Mount-only (deps pinned to inputActions): later store writes come from
+    // the machine mirror, not this seed effect.
   }, [inputActions])
 
   if (blank && composerPhase === 'blank') return null

packages/client/ui-conversation/src/client/skeleton/InputBar.tsx

@@ -31,7 +31,11 @@ export function InputBar({
   variant, placeholder, accessory, overlay, leftItems, rightItems, onAdd, addLabel = 'Add attachment',
 }: InputBarProps) {
   const input = useInput(s => s)
-  const notice = useSyncExternalStore(keyboard.notices.subscribe, keyboard.notices.getSnapshot)
+  const noticeStore = keyboard.notices
+  const notice = useSyncExternalStore(
+    (fn: () => void) => noticeStore.subscribe(fn),
+    () => noticeStore.getSnapshot(),
+  )
   const promptError = useSession(s => s.promptError)
   const running = useSession(s => s.running)
   const disabled = useSession(s => s.removed)
@@ -75,6 +79,8 @@ export function InputBar({
     // Shift+Enter is the native newline UNCONDITIONALLY — decided before the
     // IME guard so a composition-closing Shift+Enter still breaks the line.
     if (e.key === 'Enter' && e.shiftKey) return
+    // keyCode 229 is the legacy IME-composition signal engines emit without isComposing.
+    // eslint-disable-next-line @typescript-eslint/no-deprecated
     const composing = composingRef.current || e.nativeEvent.isComposing || e.nativeEvent.keyCode === 229
     if (e.key === 'ArrowUp' || e.key === 'ArrowDown') {
       if (keyboard.arbitrate(e.key === 'ArrowUp' ? 'up' : 'down', composing) === 'consumed') e.preventDefault()
@@ -92,7 +98,7 @@ export function InputBar({
       // the browser stack cannot represent); never let the native stack run.
       e.preventDefault()
       if (machineBusy || locked) return
-      const redo = e.key === 'y' || (e.shiftKey && (e.key === 'z' || e.key === 'Z'))
+      const redo = e.key === 'y' || e.shiftKey
       if (redo) keyboard.redo()
       else keyboard.undo()
       return
@@ -134,6 +140,8 @@ export function InputBar({
     if (machineBusy) return // submitting is the read-only span; adjudicating holds the pending lock
     const next = e.target.value
     keyboard.setDraft(next)
+    // selectionStart is number|null in lib.dom; the eslint program narrows it.
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
     keyboard.track(next, e.target.selectionStart ?? next.length)
   }
 
@@ -145,10 +153,13 @@ export function InputBar({
   // too (one char = one step). Mouse selection of a chip is handled in the
   // backdrop click handler below. Undo/redo must NOT reach the browser: the
   // machine owns the transaction log.
+  // selectionStart/End are number|null in lib.dom; the eslint program narrows them.
+  /* eslint-disable @typescript-eslint/no-unnecessary-condition */
   const selectionOf = (el: HTMLTextAreaElement) => ({
     start: el.selectionStart ?? 0,
     end: el.selectionEnd ?? el.selectionStart ?? 0,
   })
+  /* eslint-enable @typescript-eslint/no-unnecessary-condition */
 
   const onCopyOrCut = (e: React.ClipboardEvent<HTMLTextAreaElement>, cut: boolean): void => {
     const el = e.currentTarget