fix(tui): roll over compact counts to M at 999,950

[Hotragn]

Issue for this PR

Closes #33947

Type of change

• Bug fix

What does this PR do?

Locale.number() formats the thousands value with toFixed(1), so any count from 999,950 to 999,999 rounds to 1000.0 and renders as 1000.0K. The >= 1000000 branch never gets a chance to promote it, because the count itself is still under a million. It shows up in the TUI context indicator on ~1M token context models, e.g. 1000.0K (100%).

Rolling over at 999,950 — the point where one-decimal rounding first reaches 1000.0K — makes those values render as 1.0M. Nothing below that boundary changes.

How did you verify your code works?

Added a case to packages/tui/test/util/locale.test.ts: 999,949 still formats as 999.9K, 999,950 and 999,999 now format as 1.0M, plus the plain/K/M cases so the fix can't regress them. 3/3 pass in that file.

No screenshot — reproducing it in the UI needs a session grown to ~999,950 tokens, so the boundary is covered by the unit test instead.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

⚠️ Duplicate found:

PR #47523: fix(tui): roll over compact counts to M at 999,950

• fix(tui): roll over compact counts to M at 999,950 #47523

This is the exact same fix addressing the same issue—rolling over compact number formatting to display "M" at the 999,950 threshold instead of showing "1000.0K". Since PR #47523 already exists with identical scope and solution, PR #48969 appears to be a duplicate.

[Hotragn]

Same as above — the body links Closes #33947 (open); the needs:issue label appears to have landed before the description was saved.