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.
Stage now re-reads the pane after typing (every 50 ms, up to 1 s) and
issues a receipt only for a frame with the same generation, the input
revision its own write moved, and a composer hash equal to the
message's. Codex repaints 30 to 60 ms after the keys, so the first
capture was often stale and stage refused with the text already typed.
Every refusal after typing now says the message may be in the composer
and points at the Ctrl+U recovery. A visible-frame capture reads the
screen and the caret in one tmux invocation, with the old two calls as
the fallback.
Codex draws its suggestion popups above the composer and keeps the
footer, so a staged /stat verified and submit ran /status. Stage now
refuses a leading / or ! and a last word starting with @ or $ before
typing, and stage and submit refuse a frame with popup rows just above
the composer. The pattern and characters are registry data
(composerPopupLine, composerCommandPrefixes, composerCompletionSigils),
read from the codex 0.162.0 bottom_pane sources.
Submit waits until 250 ms after the staged keys: codex turns an Enter
within 120 ms of a typed burst into a newline. POST .../input answers
409 with its seq returned while a guarded submit holds the input lease,
instead of 200 for bytes it never wrote.
Also align the attribution memo comment with the code (a verified file
whose incremental scan fails is not re-walked, since the full walk
reads a superset), and list stage as a fromUser source in CLAUDE.md.
Aamer Akhter