Why: the chat column must host the danger-command confirm interaction inline (anchored, blocking hint, collapsed once resolved), cardlinks must locate their inbox card (D32), files dropped on the conversation must attach, and the slash menu must reflect the command registry (same source as buttons/cards/chat, D27).
Evidence: vitest 9/9; tsc clean; delegation-only logic (rendering covered by ui InlineConfirmCard suite, dispatch by backend e2e).
Impact: Conversation renders anchored confirm cards via @ui InlineConfirmCard with openInbox locate (store helper), PartCard cardlink click locates the inbox card, chat-body accepts file drops through the existing upload path, composer hints while a confirm is open, CommandMenu tolerates commands without a slash alias and marks danger=high.
Refs: docs/proposals/2026-09-30-ui-inbox-command-workspace.md T3; task card feature/command-bus-r1
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