Fable Low Power

Fable Low Power Mode

A power profile, not a new orchestrator. This skill defines what CHANGES when your Anthropic usage limits run low, and how the mode switches.

State machine

State file: ~/.claude/fable-low-power.json · Sensor: ~/.claude/skills/fable-low-power/limit-sense.sh

• Signal: rate_limits.five_hour/.seven_day.used_percentage from the statusline payload Claude Code pipes per render tick, teed to ~/.claude/cache/statusline-payload.json by statusline-tee.sh. No credentials involved. If you replace the statusline script, keep the tee.
• Modes: auto (default — thresholds decide) · on / off (manual, outranks auto).
• Auto thresholds (in the state file): ON when 5h ≥ 60% or 7d ≥ 75%; back OFF only when 5h < 40% and 7d < 65% (hysteresis, no flapping). Reading stale >30 min → hold last state.
• Trigger: low-power-mode.sh announces ON at session start and mid-session flips at prompt boundaries. Announcements instruct the session to invoke this skill.

Subcommands (when invoked as /fable-low-power …)

Usage tracking

The statusline tee also writes a per-session ledger: ~/.claude/cache/usage-sessions/<session_id>.json — cumulative model, cost, and main-loop token totals, atomically overwritten per tick (last write = session totals). limit-sense.sh aggregates it into:

• fable_today — sessions whose main loop matches model_match (default "fable", editable in the state file), active today: count, cost_usd, in/out tokens. out_tokens is the main loop only, so it's the closest proxy for "what the frontier model itself generated"; cost_usd includes in-session subagents.
• fable_7d — same over the trailing 7 days (matches the weekly limit window).
• workers_today — interactive sessions on other models. Headless -p runs never tick a statusline, so they don't appear.

The low-power banner surfaces this as "📈 Frontier burn: …". Ledger files older than 8 days are pruned by the reader. Day attribution = a session's last-active day (sessions spanning midnight count once, on the later day).

The profile — what ON changes

ON hardens "the frontier model orchestrates, cheaper models execute" from default to hard rail:

1. The frontier model's token budget buys judgment only: routing decisions, task specs, verdicts, taste calls, plans, and the reply to the user. Nothing else.
2. No inline execution. Searches, greps, probes, bulk file reads, builds, test runs, fixes, doc/deliverable drafting — ALL go to subagents on cheaper models (e.g. Sonnet for well-specified work, Haiku for scans). Agents return digests; bulk artifacts travel as file paths — the frontier model never pages through raw content it can have summarized.
3. Supervision stays on: task specs written junior-clear (exact paths, commands, expected output, "on ANY surprise stop and report"), and load-bearing claims spot-verified — via a cheap verify agent, not by the frontier model re-reading everything.
4. One-screen replies, batched judgment. Accumulate small rulings and deliver them together; one fix-worker per findings list, never one per finding; no long syntheses in chat — files.
5. Park what doesn't need frontier judgment. If a task needs no frontier call at all, dispatch it whole or park it with a one-line note.
6. Floor, not theater: if a dispatch would plainly cost more total tokens than a trivial inline action (a one-line edit, a date), do it inline. Low power saves tokens, not ceremony.

Unchanged — these outrank the profile

• The quality bar never drops: if no affordable model clears a task's bar, stop and tell the user — never silently ship degraded work.
• Your project's own workflow rules (review gates, PR rituals, approval steps) keep their routing; this profile only governs everything else.