The unit harness proves WHICH candidate gets forwarded; the ordering is
the half that shipped the bug, and only a real xterm shows it. The new
browser case dispatches the character's keydown, its composed insertText
and Enter's keydown in ONE page task, the shape an Android soft keyboard
delivers through a single InputConnection transaction, and asserts what
reaches the send path.
Verified in both directions on this machine: with the drain in place the
wire is `o\r`; with the drain removed (master's behaviour) it is `\r` and
the character is gone entirely, because by the time the zero-delay timer
runs xterm has emitted the `\r` and bumped the canonical counter past the
candidate's snapshot, so the candidate stands down. The other four cases
pass in both states.
CLAUDE.md now names the decision point, what it costs (a keydown decides
with less evidence than the timer did) and why that is safe for Enter,
and says that the pin lives in a suite the CI gate does not run.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The previous shape guessed the character from `event.key` on keydown, re-emitted
it, and then tried to suppress a late canonical copy with a 250 ms
character-keyed dedupe. Review found three defects in that, all reproducible:
the dedupe matched on the character alone with nothing scoping a candidate to
the keydown that created it, so the same character typed twice inside the window
had its second, real byte swallowed; anything whose committed text differed from
`event.key` (Enter, IME punctuation) was delivered twice, because the dedupe
could never match it; and the trigger ignored `key === 'Unidentified'`, which is
what a soft keyboard reports, so it may never have fired where it was needed.
The input event already carries the committed text in `ev.data` — exactly what
xterm itself would have forwarded — so nothing has to be guessed. The controller
now only decides WHETHER to forward, by asking whether xterm produced canonical
data since the keydown that began the keystroke. No character-keyed matching
survives, so the first two defects are structurally impossible rather than
defended against, and nothing reads `key`/`keyCode`, so the third cannot recur.
Three details are load-bearing and each has a test that fails without it:
- The "did xterm speak?" snapshot is taken at KEYDOWN, not at the input event.
`_keyPress` emits and sets `_keyPressHandled` before `input` fires, so a
snapshot read at input time already contains that emission, reads it as
silence, and delivers the character twice.
- Our `input` listener is registered with `capture: true`. The target is visited
twice in the event path, so a capture listener calling `stopPropagation()`
stops later BUBBLE listeners on that same target; xterm's `cancel()` runs
exactly in the branch where it handled the input, so on bubble we would never
observe handled events, and whether we observed them at all would hang off
`options.cancelEvents`. Measured in jsdom and headless chromium; the table is
in the module header.
- Enter is deliberately no longer special-cased. That mapping is what made the
committed text differ from the re-emitted value in the first place.
The scope is also narrower than the old name suggests, and the browser test now
proves it rather than assuming it. For a keydown that reports keyCode 229 xterm
ALREADY self-rescues, via `CompositionHelper._handleAnyTextareaChanges()`
diffing the helper textarea on a 0 ms timer. A test asserting "we recovered it"
there passes while xterm does all the work, so the browser tests assert WHO
delivered the byte: zero canonical emissions for the genuinely orphaned case,
exactly one delivery for the case xterm rescues itself.
Also addresses review notes: the module gains an `@fileoverview` with
`@dependency`/`@loadorder` and an entry in the load-order list and module
inventory, and the wiring test moves out of the Ctrl+C smart-copy file into its
own. The keydown hook deliberately still runs for every key event rather than
moving behind the 229 gate: gating it would reinstate exactly the blindness
described above, and it is now a single counter assignment.
Codeman maintainer