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-primitives/src/Button.tsx

@@ -19,7 +19,7 @@ export function Button({ variant = 'ghost', size = 'md', icon, className, childr
   variant?: ButtonVariant
   size?: 'md' | 'sm'
   icon?: ReactNode
-  className?: string
+  className?: string | undefined
   children?: ReactNode
 } & ButtonHTMLAttributes<HTMLButtonElement>) {
   return (

packages/client/ui-primitives/src/Tooltip.tsx

@@ -27,7 +27,8 @@ interface AnchorProps {
  * Attach a hover/focus tooltip to an anchor element.
  * @param props.label - bubble text.
  * @param props.side - placement relative to the anchor (default 'right').
- * @param props.disabled - suppress the bubble while true; the anchor renders identically so toggling never remounts it (which would cut its CSS transitions).
+ * @param props.disabled - suppress the bubble while true; the anchor renders identically so
+ * toggling never remounts it (which would cut its CSS transitions).
  * @param props.children - a single anchor element; its own ref (callback or object) is forwarded alongside the tooltip's.
  * @returns the cloned anchor plus a fixed-position bubble while hovered/focused.
  */

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

@@ -20,6 +20,9 @@ export interface CodeBlockProps {
 
 /** @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.
+  /* eslint-disable-next-line @typescript-eslint/no-unnecessary-condition */
   if (navigator.clipboard?.writeText) {
     try {
       await navigator.clipboard.writeText(text)
@@ -30,6 +33,9 @@ async function writeClipboard(text: string): Promise<boolean> {
     }
   }
   // 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.
+  /* eslint-disable @typescript-eslint/no-deprecated */
   const exec = typeof document.execCommand === 'function'
     ? document.execCommand.bind(document)
     : undefined
@@ -48,6 +54,7 @@ async function writeClipboard(text: string): Promise<boolean> {
   } finally {
     el.remove()
   }
+  /* eslint-enable @typescript-eslint/no-deprecated */
 }
 
 export function CodeBlock({ code, lang, className }: CodeBlockProps) {
@@ -73,9 +80,9 @@ export function CodeBlock({ code, lang, className }: CodeBlockProps) {
       <pre className={css.plain}><code>{trimmed}</code></pre>
     )
     : (
-  // eslint-disable-next-line react/no-danger -- shiki's output is a static
-  // span tree it generated from `code` (no user HTML passes through), the
-  // sanctioned innerHTML consumption path per shiki's own docs.
+  // shiki's output is a static span tree it generated from `code` (no user
+  // HTML passes through), the sanctioned innerHTML consumption path per
+  // shiki's own docs.
       <div dangerouslySetInnerHTML={{ __html: html }} />
     )
 

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

@@ -15,6 +15,8 @@ export function JsonBlock({ label, payload, defaultOpen = false }: {
     if (!open) return ''
     let s: string
     try {
+      // lib typing hides stringify's undefined arm (undefined/function/symbol payloads).
+      // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
       s = JSON.stringify(payload, null, 2) ?? String(payload)
     } catch {
       s = String(payload)

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

@@ -53,7 +53,9 @@ function buildComponents(streaming: boolean): Components {
     // plain arm — retokenizing a growing fence on every chunk is quadratic
     // main-thread work; the finalize swap highlights it once.
     pre: ({ children }) => {
-      /* v8 ignore next 2 -- the markdown pipeline always hands `pre` its single `code` element; the undefined arm guards a react-markdown representation change. */
+      // The markdown pipeline always hands `pre` its single `code` element;
+      // the undefined arm guards a react-markdown representation change.
+      /* v8 ignore next 2 */
       const child = isValidElement<{ className?: string; children?: unknown }>(children) ? children : undefined
       const raw = child?.props.children
       // A fence whose content isn't one plain string (e.g. an empty fence)