Desktop: buzz://message deep links into forum channels open the post list, never the post #7315

buzz://message deep links into a forum channel open the post list and never select the post. The message is unreachable from its own "Copy link".

All citations at origin/main = 2ac0aa1dd.

Correction (edited). The first version of this issue cited 7e34bee62, which is 17 commits stale on these files, and claimed two additional defects that #5889 (207154706, "fix(desktop): support channel message path links") had already fixed. Those claims are withdrawn — see "Already fixed" below. The forum defect is unaffected and verified to persist on current main.

The canonical format works — for stream channels only

buzz://message?channel=<uuid>&id=<eventId>[&thread=<rootId>] is parsed, validated, and dispatched by the Some("message") arm at desktop/src-tauri/src/deep_link.rs:675, then routed by desktop/src/shared/useMessageDeepLinks.ts:20-45. For stream channels this is correct: root links open the reply panel, reply links open and scroll it (desktop/src/features/channels/ui/useChannelRouteTarget.ts).

The defect

Deep links call goChannel unconditionally and never goForumPost:

// desktop/src/shared/useMessageDeepLinks.ts:35-38
return goChannel(payload.channelId, {
  messageId: payload.messageId,
  threadRootId: payload.threadRootId,
});

The /channels/$channelId route it lands on is structurally incapable of selecting a forum post:

1. desktop/src/app/routes/channels.$channelId.tsx:83,85 hardcode selectedPostId={null} and targetReplyId={null}
2. desktop/src/features/channels/ui/useChannelRouteTarget.ts:109 returns early, before any thread handling, when activeChannel.channelType === "forum"

So a deep link to a forum post or comment lands on the channel's post list with nothing selected, regardless of thread=. The in-app markdown handler has the same gap — desktop/src/shared/ui/markdown.tsx:1711-1716 also routes every message link through goChannel.

The route that would work already exists and is never used by deep links: /channels/$channelId/posts/$postId?replyId=… passes selectedPostId={postId}.

In-repo precedent for the fix

Search already solves exactly this. openSearchHitWithNavigation resolves a destination first and branches to goForumPost for forum targets — desktop/src/app/navigation/searchHitNavigation.ts:30,59-60, with the resolver at desktop/src/app/navigation/resolveSearchHitDestination.ts, which fetches the event and derives postId from getThreadReference(event.tags) for KIND_FORUM_COMMENT.

Suggested fix: a resolveMessageLinkDestination(channelId, messageId, threadRootId) mirroring that kind-based branching, consumed by both useMessageDeepLinks.ts and the markdown handler.

Two stale comments to correct in the same change

Both assert the current behaviour is fine. Both are wrong, and they are why this gap is easy to miss:

• desktop/src/features/messages/lib/messageLink.ts:17-21 — says threadRootId is "not consumed by the click handler or deep-link listener". Both consume it.
• desktop/src/shared/useMessageDeepLinks.ts:16-18 — says routing via goChannel "works for both stream replies and forum threads". It does not work for forum threads; that is this issue.

Already fixed by #5889 — not part of this issue

Recorded so the next reader doesn't re-report them against an old build:

• Cold-start race — handled by the durable PendingNavigationDeepLinks pull-queue (deep_link.rs:34) plus listenForNavigationDeepLinks on the TS side.
• Path-style buzz://channel/<uuid>/<64-hex-id> — accepted as a compatibility form with window activation (deep_link.rs:661).

A released 0.5.11 predates #5889, which is why the original reporter saw "Buzz opens but doesn't navigate."

Adjacent, not in scope

ReminderDestination is channel-only (desktop/src/features/reminders/lib/reminderNavigation.ts), so a reminder on a forum comment fails the same way. Same root cause, separate fix.

Verification

cargo test --manifest-path desktop/src-tauri/Cargo.toml deep_link at 2ac0aa1dd: 50 passed, 0 failed. No test covers a forum-channel message deep link.