benchkeeper 6.21

• App, usage per account and limit notices (#338, part of #300): benchkeeper accounts track <name> [--off] adds a status line script and a StopFailure hook (rate_limit, authentication_failed, billing_error) to a Claude Code account's folder, as a plan with a diff and undo (a dev container account is written through devcontainer exec); an existing status line of another kind is refused. The script keeps only the used percentage and reset time of the 5-hour and 7-day window and the type and time of a failed turn, never a credential. accounts status (--json key usage), doctor and the Accounts view show what is left per window (100 minus used_percentage; a window past its reset time is unknown, not full), a notice below twice the minimum and the latest failure.
• accounts limits [name] sets the minimum headroom (defaults 8 percent for the 5-hour and 3 percent for the 7-day window, per account too), the notice level, --pool and the launch settings. run below the minimum shows the account, window, what is left and the reset time and asks before it starts (--yes or --continue-below on starts anyway). Opt-in auto-pick, off by default (--auto-pick on): a launch without --account under a default account below its minimum starts under the pool member with the most headroom, or stops with the earliest reset time, or with --when-none wait waits for it; never inside a running session. The provider's consumer terms prohibit bypassing protective measures and are silent on switching accounts at a limit, so the setting says so and the owner carries that call. Codex has no documented usage source and shows none.
• Breaking, before 7.0 (no compatibility path): accounts list --json has pool and limits per account and settings; accounts status --json has usage per account; accounts.json may hold settings and, per account, limits and pool.
• Plugin version 6.21.0.
• Upgrade: npx benchkeeper@6.21.0 apply.