Sidebar: show when a thread's pull request needs you, with a "Needs attention" filter

[filipgutica]

I'd like agreement on direction and scope before I write any code.

Problem

When I run several agents, the sidebar tells me when a thread needs an answer or an approval, but not when the thread's pull request needs me. Failing checks, a "changes requested" review, and new review threads only show up on GitHub, and then I have to find the thread that owns the PR. #16459, #19085 and #21251 each describe part of the same gap.

I also can't filter down to the threads that need me. With 20+ threads, I end up scanning every row for Input or Approval.

Proposal

1. Use the row's existing status slot

The top line of a sidebar row already shows Input, Approval, Failed, Working and Done. I'd add three reasons to that slot:

• Checks failed, when a linked open PR has failing checks.
• Feedback, when a linked PR has changes requested or unresolved review threads.
• Plan ready, when a proposed plan is waiting for review.

The most urgent reason takes the slot, and +N counts the other kinds. Working still takes the slot and its timer while the agent runs, so a thread whose agent is fixing its failed checks shows "Working 4m +1".

When a thread has several reasons at once, the slot shows the top one plus the count:

2. Attention card

The badge is a button. It stays visible when you hover the row, with Snooze and Settle beside it, the same way the "Woke" badge does when a snoozed thread wakes up. Clicking it opens a card with every reason, grouped by the thread and each linked PR. Each reason has one action: Open thread, View review, or View threads. Opening the thread clears the thread's own reasons. PR reasons clear when the PR changes: checks pass, threads get resolved, or the PR merges or closes. The row's existing details card on hover doesn't change.

3. "Needs attention" filter

The filter is a switch at the top of the existing project filter menu, and it combines with the project scope. While it's on, a chip under Search shows it, and the chip's × turns it off. When nothing needs attention, the list says so and offers a way back to all threads.

Scope

Web and desktop only, with no contract changes.

Failed checks and changes requested come from checksState and reviewDecision. The thread shell already carries both for each linked PR, and PullRequestSyncReactor keeps them current, so these two need no new reads. Unresolved review threads need the PR activity read, which means one cached read per open linked PR on unsettled threads.

Seen state uses the server-side lastVisitedAt, so opening a thread on one device clears it on the others.

This adds no OS or push notifications and leaves the existing notification paths alone.

I've used a version of this every day in a fork for a few weeks. This proposal leaves out the fork-specific parts and uses only the native thread and PR data.

Questions

1. Is the status slot the right place, or should PR state stay off the row?
2. Is the project filter menu the right home for the switch?
3. Should unresolved review threads be in v1, given the extra activity read, or should v1 ship only checks and review decision?
4. Is a mobile follow-up wanted? It would build on Mobile: show checks, review and watch state for linked pull requests, like desktop #20212.