- src/web/routes/session-routes.ts:2102: the guarded-submit 409 now applies to tagged input (clientId + seq) only; untagged input is held like a WebSocket frame. The raw write (:2228) goes through holdForGuardedLease and answers 200 once held (a send-and-wait reads `delivered` from the held write; a full queue releases the waiter and answers 409); a mux write takes its own turn in writeViaMux.
- test/guarded-lease-held-input.test.ts: real-Session route tests for an untagged raw POST during the lease (written after the Enter) and a held send-and-wait (delivered: true); both fail without the fix.
- test/routes/session-routes.test.ts + test/mocks/mock-session.ts: the 409 test now covers tagged input only; new tests for untagged raw (held), untagged mux (own turn) and a full hold queue (409); MockSession gains holdForGuardedLease/releaseGuardedLease and a lease-aware writeViaMux.
- src/session.ts:4787 (guardedInputHeld JSDoc) + write() + docs/architecture-invariants.md: write() refuses during the lease only, so cron's paste mode can land ahead of input still draining.
- docs/api-reference.md: the input route's 409 is for tagged input; untagged input is held.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The input lease is held across the awaited tmux Enter, so WebSocket frames
keep arriving while it is held. A tagged frame (seq N) was refused and its
seq rolled back, but the browser's WebSocket path does not wait for ACKs:
seq N+1 landed after the lease and moved the watermark past N, and the
redelivered N was then dropped as a duplicate. The keystroke was lost.
Input that arrives during the lease is now held and written in arrival order
when the lease is released, whatever the submit's outcome. A WebSocket frame
is applied and ACKed only once written; managed writes (writeViaMux) and
named keys (send-key) wait for their turn the same way, and a held write that
is still being sent holds everything behind it. A keystroke held before the
guard runs still moves the input revision, so it still invalidates the Enter.
The hold is capped per lease (256 inputs, 1 MiB): past it the WebSocket is
closed with 1013 and nothing later from it is applied, so the browser resends
every unACKed frame in order, and send-key answers 409 CONFLICT instead of
logging a tmux failure as INTERNAL_ERROR. POST .../input keeps its 409 for the
lease plus the held input's drain; its browser drainer is serialized.
Docs: correct the api-reference paragraph that said these keystrokes are
redelivered, and describe the capture fallback and the per-scope cursor cap
from the previous two commits in api-reference, architecture-invariants and
the changeset.
Codeman maintainer