fix(usage): only publish settled /usage reads — kill phantom quota alerts

[Time4Mind]

Problem

@Alexes_claude_bot pushed three quota alerts in one minute — 🟡 week: 68%, 🟡 week: 68%, 🟠 week: 78% — while the live weekly usage was 2% (confirmed via /usage: session 7%, week 2%, week-Sonnet 0%).

Proof the 78% was never real: the week resets Jun 21; usage only climbs within a week, so it can't read 78% at 14:31 and 2% an hour later. The 78% was a stale pre-reset value (last week's high), surfaced by the usage poller.

Root cause

_poll_usage_modal waits for two consecutive agreeing captures (resolved), but the fallback returned an unsettled frame anyway:

return info if (resolved or info is not None) else None

And _capture_with_scrollback reads ~100 lines of scrollback, which can still contain a previous /usage render. After the weekly reset, the parser walks that stale render and extract_usage_breakdown can surface last week's high pct. quota_alerts (process-local baseline, reset by the bot's frequent restarts) then reads 0 → 78 and fires phantom 50%/75% crossings. Network flaps (the same instability behind the bot's restarts) bunched/duplicated the delivery into one minute.

Fix

• Don't publish unsettled reads — _poll_usage_modal returns None unless two consecutive captures agree. A missed poll is harmless; the loop retries on the next 10-min cadence.
• Drop stale scrollback before reading — new _clear_pane_history clears the pane buffer, and an Escape dismisses any leftover modal/feedback-prompt, so a pre-reset render can't be parsed as the current week.

Tests

tests/ccbot/bot/test_usage_window.py:

• a settled read (two agreeing captures) is published;
• an oscillating, never-settling read returns None instead of the last frame (the old bug).

Full suite green (742 passed), pyright (strict, src/ccbot) + ruff clean.

🤖 Generated with Claude Code