VS Code Codex extension hangs when opening previous thread; thread state broadcasts have no handler

What version of the IDE extension are you using?

Unknown

What subscription do you have?

Pro

Which IDE are you using?

VS Code

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

Opening a previous task thread from history hangs indefinitely. New threads work.

This seems to affect longer threads. I don’t have direct proof of causation, but every thread I’ve seen fail to open had previously gone through a “compacting content” step at least once. Shorter threads that did not compact appear unaffected.

Regression timing: observed after GPT-5.5 release/update.
Unexpected behavior: previous thread shows model changed from GPT-5.5 to GPT-5.4 without user action.
Expected: previous thread history should hydrate and allow follow-up messages.

Relevant log lines:
[IpcClient] Received broadcast but no handler is configured method=thread-stream-state-changed
[IpcClient] Received broadcast but no handler is configured method=thread-read-state-changed
Request failed ... method=plugin/list ... Invalid request: AbsolutePathBuf deserialized without a base path

What steps can reproduce the bug?

Start or use a long-running conversation thread.
Continue using it until the app performs a “compacting content” step.
Leave the thread, refresh, or return to the thread list/history.
Try to reopen that same thread.
Observe that the thread fails to open or does not load correctly.
Compare against a shorter thread that has not gone through compacting; those appear to open normally.

What is the expected behavior?

_No response_

Additional information

_No response_