docs(suggestion-menu): document the suggestion menu

[kianbazza]

Summary

Documents SuggestionMenu: a docs page and an API reference, with a live primitive example (@ mentions in a textarea).

The page covers:

• connecting a host through the handle;
• text fields with useTextTrigger, including trigger options and replacing the match;
• editors, with a ProseMirror plugin recipe that includes Escape stickiness;
• async results, with a TanStack @ mention search using placeholderData: keepPreviousData and debounce, plus the note that deep search's 'block' still shows Loading between searches. A "searching…" indicator reads isAnyFetching from useAsyncMenuCoordinator(), which returns null without asyncContent;
• noResults;
• the keymap;
• placement;
• accessibility: host attributes by element, aria-activedescendant, the result summary and getAriaResultsText.

SuggestionMenu joins the docs type entry so the API reference tables render. The sidebar lists the page, and the page ends with a link to the API reference, as the dropdown menu's does.

Evidence

• Forced type-gen adds the SuggestionMenu types, and every type the reference names exists.
• fumadocs-mdx compiles both pages.
• apps/web type-checks.
• Every claim in the page was checked against the code.

Merge Danger

Door: two-way

Blast Radius: docs only (private page)

Closes UI-566

[vercel]

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Project	Deployment	Actions	Updated
ui-canary	Ready	Preview	Sep 29, 2026 2:31pm UTC

[linear-code]

UI-566