rate-card-keeper

rate-card-keeper

Part of Pech — Cost Ledger for AI-Assisted Development.

Holds the rate card that every cost computation depends on. Rate card is committed JSON, refreshed via CI PR — never fetched at runtime (brand invariant: zero external runtime deps).

Rate-card location

shared/rate-card.json — sibling-level shared state, not plugin-local, because cost-tracker and budget-watcher both read it and keeping three copies guarantees drift.

Rate-card schema

{
  "effective_from": "2026-04-19",
  "effective_until": null,
  "currency": "USD",
  "models": {
    "claude-opus-4-7":     { "input_rate_per_mtok": 15.00, "output_rate_per_mtok": 75.00 },
    "claude-sonnet-4-6":   { "input_rate_per_mtok":  3.00, "output_rate_per_mtok": 15.00 },
    "claude-haiku-4-5":    { "input_rate_per_mtok":  0.80, "output_rate_per_mtok":  4.00 }
  },
  "modifiers": {
    "cache_write_modifier": 1.25,
    "cache_read_modifier":  0.10,
    "batch_discount":       0.50
  },
  "fallback_model_rate": {
    "input_rate_per_mtok":  3.00,
    "output_rate_per_mtok": 15.00,
    "note": "Used when a model ID is not in the rates table. Rows using this fall-back are tagged rate_card_stale:true."
  },
  "_meta": {
    "source": "https://www.anthropic.com/pricing",
    "verified_by": "CI nightly refresh job",
    "last_verified": "2026-04-19"
  }
}

Staleness policy

• 0–60 days old: normal operation.
• 60–90 days old: load-rate-card emits pech.rate_card.stale.warning at SessionStart.
• > 90 days old: all ledger rows computed against this card are tagged rate_card_stale: true — forecasts flag themselves as potentially off.
• > 180 days old: load-rate-card fails hard at SessionStart — refuse to observe until refreshed. Cost data under a half-year-stale card is dangerously wrong.

Refresh mechanism

Nightly GitHub Actions workflow at .github/workflows/refresh-rate-card.yml (ships separately — this plugin describes the contract, not the CI). The job:

1. Scrapes Anthropic's published pricing.
2. Diffs against shared/rate-card.json.
3. On diff, opens a PR with the update, CC'ing @enchanter-ai/maintainers.
4. On no diff, updates _meta.last_verified and commits directly.

Never fetches at runtime. Never caches. The JSON is authoritative.

Inputs

• Hook event: SessionStart
• Rate card: shared/rate-card.json

Outputs

• Event bus: pech.rate_card.refreshed (on first load of a newer-than-prior-session card), pech.rate_card.stale.warning (60-90 days), pech.rate_card.stale.blocking (>180 days)

Events

Publishes: pech.rate_card.refreshed, pech.rate_card.stale.warning, pech.rate_card.stale.blocking

Subscribes: none

Brand invariants

• Zero runtime deps — the card is a committed file, not an HTTP fetch.
• Staleness is a first-class signal, not a silent drift.
• Schema validation at SessionStart (Haiku) catches breaking changes early.