captureBaseline stored the raw, unclipped last-assistant block while resolve()
compares against clip(...) capped at MAX_SCRAPE_CHARS. For a block longer than
4000 chars the two capped representations never match even when the pane is
unchanged, defeating the CB-115 misattribution guard and letting a stale
completion resolve a rapid back-to-back send. Clip the baseline identically.
Regression test: an unchanged >cap block stays suppressed.
Surfaced by the fan-out issue-hunt E2E (1 primary -> 3 concurrent workers,
e2e/issue_hunt_test.py, added here). The same hunt's WorkerService.stop() and
Rendezvous.complete() findings were verified as false positives (locatePane is
already guarded; the sender's finally-close already removes the waiter).
Closes#2