[kazemek21]

TL;DR

Adds conversation.ui.Conversation, a public host-owned scope that lets a plugin's own ui.Message rows and ui.Composer for one channel get native Edit, confirmed Delete with recovery and retry, and host media review. Mounting it never marks anything read, follows a thread or enters the channel visit. Cross-channel overview cards need this; today a bare ui.Message row has neither Edit nor Delete, and ui.Thread always visits.

Fixes NEXUS-4193

How it works

ui.Conversation({ session, scope, channelId, channelName?, threadId?, children(interactions) }) renders the existing ConversationChannel in its host-dialog, non-visiting mode (host plus active={false}). Inbox Drafts already uses this mode internally. Inside it:

• MessageManagement supplies the row menu's Edit/Delete under the existing permission checks, the delete confirmation and the failed/unconfirmed recovery notice.
• MessageEditScope makes Edit target the ui.Composer in the same scope. A scope without a composer offers no Edit, as in other previews.
• ConversationHost owns media review and panel overlays, focus return, and the existing stale-session guard (nothing opens once the relay snapshot is no longer this ready session).

children receives the host's onOpenLink, canOpenLink and onOpenMediaReview to pass to the rows. EmbeddedThread and the new scope now share one HostedChannel wrapper, so ui.Thread behavior is unchanged. No changes to MessageManagement, ConversationHost, MessageComposer or contracts.ts.

Evidence

src/features/conversation/EmbeddedConversation.test.tsx mounts two fictional channel cards (real relay session, real ui.Message rows and ui.Composer from ConversationService; only MediaReviewViewer is reduced, since it has its own suites). It covers:

• the same rows without the scope have no Edit/Delete; inside it, each card offers both
• mount, background presentation, re-present and unmount never call enterChannel, leaveChannel, follow, markMessageRead, markChannelRead or the roster's profiles.reserve, and publish nothing
• Edit fills only that card's composer and publishes a kind-40003 edit tagged with that card's channel. The other card's message is untouched.
• Delete: cancel publishes nothing; confirm publishes kind 5; a relay rejection shows the recovery notice in that card only; Retry resends the same event id and the row goes away
• media review opens with the card's channel and message, and stops opening after the session stops being ready

Fail-then-pass: with active={false} removed from the scope, all 4 tests fail (enterChannel and profiles.reserve are called). The scope restored, all pass.

The packed @buzz/author consumer fixture (tests/fixtures/conversation-consumer) now renders its rows and composer inside ui.Conversation and passes interactions.onOpenLink to its rows. So the generated declarations must export the new component and its children(interactions) type, and the existing conversation.spec.mjs journey mounts it in the real app. The fixture type-checks against freshly built declarations. As a negative control, a misspelled interactions field fails tsc.

Run on a Linux Blox box on base a34ba4f (the local host-build guard refused under load):

• vitest run src/features/conversation src/features/messages/MessageManagement.test.tsx src/bundled/inbox/DraftsView.test.tsx: 19 files, 221 tests passed
• tsc --noEmit and biome check --error-on-warnings on the touched files: clean
• pnpm author:build, packed and installed into a copy of the consumer fixture, then pnpm build (tsc): clean

No browser journeys were added or removed. The existing consumer journey now mounts the scope; it runs only in hosted CI, not locally. Focus, overlay and native-edit geometry are unchanged existing ConversationHost/composer behavior that existing suites already cover.

Limits and coordination

• Not exercised in the native desktop app or a browser journey. Hosted CI runs the full suites.
• Two ui.Conversations for the same channel each show that channel's recovery notice, because recovery is per channel. The docs say to render one per channel or card.
• No overlap in hunks or behavior with feat(solo): let a plugin arrange the Solo list and add a row action #2483 (Solo list arrangement/row action in service.tsx), NEXUS-4029: Add task source references and primary controls #1889, NEXUS-4022: Create durable task chats in New Chat #2306 or NEXUS-4022: Preserve Nexus metadata in existing composer tokens #2303 (contracts.ts), NEXUS-4082: Keep the new-message boundary stable during a visit #2083 (MessageManagement.tsx) or feat(messages): forward a message to a person #2167 (ConversationHost.tsx). This PR does not edit contracts.ts, MessageManagement.tsx or ConversationHost.tsx.
• This PR doesn't adopt the scope in any plugin. That is separate work.

Initiative context

Buzz Threads status

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