Race condition: Continue/Cancel button handlers were firing submitBlocking()
without awaiting it, then immediately calling close() which tore down the
modal. If the fetch got delayed or dropped by the DOM teardown, the Python
thread would stay blocked on event.wait() until the full timeout.
Symptoms: "sometimes Continue gets stuck and doesn't advance the workflow."
Fixes:
- PathAnimator: All exit paths (Continue, Cancel, ESC, overlay click, header
close) now await submitBlocking() before close(). On Continue failure,
the modal stays open with buttons re-enabled so user can retry.
- PathAnimator: submitBlocking now checks response.ok and throws on non-2xx,
surfacing 404 "Session not found" errors instead of swallowing them.
- PathAnimator: close() safeguard still uses fire-and-forget but now with
.catch() to log errors (it's a last-resort path after primary handlers).
- ImagePicker: sendSelection now checks response.ok and throws on non-2xx.
- ImagePicker: All callers wrapped in try/catch so failed submits don't
leave the modal in a half-closed state. Confirm failures keep the modal
open with a user-visible alert.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
