Terminal pane reattachment currently clones the session and serializes the
entire 9.2 MB app state even when the binding is already in place and durable.
Add an early-return fast path that skips this work when all nine predicates
hold: no split, binding matches in-memory and on-disk, incarnation matches,
no tombstone, and generation counter proves durability.
Includes one-line fix in `writeToDiskSync` to record hash-matched sync flushes
as durable, so the fast path doesn't stay parked behind a stale generation.
Adds `persistence.pty-binding` observability spans (local NDJSON, unsampled for
mutations, budgeted for fast-lane hits) to measure eligibility rates before
and after. Includes ratchet test to ensure every binding writer bumps the
generation. Diagnostic tools and full investigation notes from September 7,
2026 capture that identified the 59–100 ms no-op binds and measured a real
terminal keystroke queued 117 ms behind one such call.
Jinwoo-H
Jinjing