Linux Chat UI Tests has been failing on turn 4 (the prompt with
embedded apostrophes) at /v1/chat/completions -> 422. Three real
causes:
1. The wait_for_function used absolute count >= idx, so a prior
turn's bubble (or any pre-existing assistant text) made the
condition trivially true and the next send fired before the
previous turn finished streaming. The 4th rapid-fire send then
raced assistant-ui's "send while running" gate and produced a
malformed body that FastAPI rejected with 422.
2. The post-turn `wait_for_selector('Stop generating', detached)`
was wrapped in try/except so the test silently advanced if the
prior turn was still streaming. Promote that to a hard wait and
take a debug screenshot if it ever times out.
3. The 4th prompt embedded apostrophes ("Say the word 'tree'..."),
which made the in-log diagnostic noisier than necessary; rewrite
it to mirror the other "Reply with exactly: X" prompts. Not the
root cause, but worth removing as a confound.
Each turn now snapshots a baseline non-empty count and waits for
exactly +1, which is what we actually want.
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