Three independent root causes of intermittent Chinese character loss
(English was unaffected because it bypasses the composition path):
1. input-cjk.js state machine: stuck _composing when compositionend never
fires (WeChat/Sogou IMEs) silently swallowed all input; the deferred
compositionend flush could reset the textarea mid-next-composition
(cancels the live IME composition on iOS); the 100ms keydown-echo
window discarded ANY input regardless of content.
2. Focus stealing: session-select / SSE-reconnect paths call
terminal.focus() (15+ call sites), landing focus on xterm's hidden
textarea; with the CJK onData gate active, everything typed there was
swallowed. Fix: focus router in initTerminal routes ALL
terminal.focus() calls to the CJK field while it is visible, plus a
self-healing onData gate that reclaims focus when it swallows input.
3. Android InputConnection wedge (9-key IMEs + Chromium): the keyboard
composes in its own UI but delivers zero DOM events. Fix: skip
redundant textarea value/selection writes (they race IME session
setup), and re-tapping the focused empty field forces a blur→focus
cycle that restarts the input session.
Diagnostics: input-cjk.js now traces every IME event/flush decision into
the crash-diag breadcrumbs; /api/crash-diag stores beacons per page-load
id (iOS PWA reloads no longer wipe the trail, concurrent clients no
longer clobber each other) and flushes on visibilitychange.
Tests: test/input-cjk.test.ts (vm-sandbox, 9 cases incl. regression
guards for all three root causes).
Teigen
443b85c18e