fix(dashboard): chat profile scoping by rotating attach token on profile change

[iosub]

Summary

This PR fixes a dashboard chat regression where switching the selected profile could still reattach to a keep-alive PTY created under the previous profile.

Problem

The chat keep-alive attach token was rotated only for forced-fresh sessions. On profile switches without fresh=1, the client could reattach to an old PTY and continue under stale profile scope.

Root Cause

Profile transitions were not treated as attachment identity boundaries.

Changes

• Track profile transitions in ChatPage.
• Rotate the PTY attach token when either:
  • forced fresh session is requested, or
  • selected profile changes.
• Reset the profile-change flag after token generation.
• Keep existing reattach behavior for reconnects when profile is unchanged.

Impact

• Prevents cross-profile PTY reattachment.
• Ensures profile-scoped sessions use the selected profile consistently.
• No server API or persistence contract changes.

Testing

• Patch applies cleanly on current main.
• Manual validation:
  1. Start chat under profile A.
  2. Switch to profile B.
  3. Confirm no reattach to profile A PTY.
  4. Refresh while staying on profile B and confirm normal reattach.

Risk

Low. Change is limited to token rotation decision logic in chat page attach parameter generation.

[Copilot]

Pull request overview

This PR fixes a dashboard chat regression where switching the selected management profile could still reattach to an existing keep-alive PTY that was spawned under the previous profile, by treating profile transitions as an attachment identity boundary and rotating the attach token accordingly.

Changes:

• Track profile transitions in ChatPage to detect when the selected profile changes.
• Rotate the PTY attach token when either a forced-fresh session is requested or the selected profile changes.
• Reset the profile-change flag after generating the attach token to preserve normal reconnect/reattach behavior when the profile is unchanged.

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[teknium1]

Thanks for isolating the attachment identity boundary. The normal profile-switch premise is confirmed on current main: web/src/pages/ChatPage.tsx:805 reuses the attach token independently of scopedProfile, while hermes_cli/web_server.py:15452 reattaches solely by that token.

Problems

• A rapid profile transition can still open a stale socket. web/src/pages/ChatPage.tsx:810 awaits api.buildWsUrl, cleanup sets unmounting = true at line 1022, and line 811 creates the socket without a post-await cancellation check. If the scope changes during that await, the cleaned-up effect can still assign wsRef.current for its old profile.
• The PR has no regression test (gh pr diff 62581 changes only web/src/pages/ChatPage.tsx). This path needs coverage for A → B rotation, unchanged-profile reconnect reuse, and a deferred URL-build/profile-change race.

Suggested changes

• Recheck unmounting immediately after await api.buildWsUrl(...) and before constructing the WebSocket.
• Add the focused regression coverage above.

Automated hermes-sweeper review.

[iosub]

Thanks for the review — both points addressed in f08c129:

1. Stale socket race — after await api.buildWsUrl(...), we now recheck the effect teardown flag via shouldOpenPtySocketAfterUrlBuild(unmounting) and return before constructing the WebSocket / assigning wsRef.
2. Regression coverage — added focused helpers + vitest coverage in web/src/lib/pty-attach.ts / web/src/lib/pty-attach.test.ts for:
   • A → B attach-token rotation
   • same-profile reconnect token reuse
   • forced-fresh rotation
   • deferred URL-build / profile-change race (abort when unmounting)

npm test -- src/lib/pty-attach.test.ts src/lib/pty-reconnect.test.ts → 15 passed.

[iosub]

Do I need to do something else?