Files
turnstone/tests
Patrick Buckley f7ca4d295d fix(coordinator): historyStale latch closes the clear_ui over-rewind window (#894)
From clear_ui arrival until the next SUCCESSFUL refetchHistory render the
visible transcript is the stale pre-rewind DOM with busy false, so a
second rewind/edit click counted it and POSTed an over-large turn count
against the already-restructured server conversation (the #890 sibling,
pre-existing since #888 accepted the stale-interactive window).

Port of interactive.js's converged #890 latch design, adapted to coord's
structure (no load token, no replay quiesce, no ref-resetting render):

- historyStale latch: set at clear_ui arrival, cleared ONLY by the
  success-path render below the if-(!hist) failure guard — a flag would
  reopen on the failed exit, which is exactly the over-rewind window.
- Gates: _rewindToMessage / _editAndResend / _startEdit now require
  busy || historyStale; _rewindToTurns and _retryLast stay busy-only
  (explicit-arg / no-DOM-count — rulings at-site).
- Heal A: one bounded turn-free retry armed in clear_ui's .then; fire
  guards read the latch, refetchesInFlight (net-new await-window counter,
  coord's quiesce-free yield discriminator — a COUNT because overlapping
  fetches are reachable), busy, the streaming refs (load-bearing: coord's
  refetch does not reset refs), and visHandler (teardown sentinel).
- Heal B: idle-edge backstop as the else-if behind the truncated-resync
  consumer — TRANSPORT-FREE by ruling (plain seedless refetchHistory;
  a reconnecting heal draws the synthetic state_change:idle back into
  its own trigger = zero-backoff storm against a recovering node).
  Carries ref guards the interactive template omits: this arm also
  serves error edges where no stream_end nulled the refs.
- Teardown: destroy() cancels the retry timer (terminal-only);
  closeStreamTransport deliberately does not (redials keep heal intent).

Static pins: the latch contract (set/clear/gate sites, transport-free
backstop, bounded arm, teardown split) + the widened guard-before-wipe
window; the contract pin fails against the pre-latch code.
2026-07-24 15:04:31 -07:00
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