## What was built
### DB schema
- `timmy_config` table: key/value store for the generosity pool balance
- `free_tier_grants` table: immutable audit log of every Timmy-absorbed request
- `jobs.free_tier` (boolean) + `jobs.absorbed_sats` (integer) columns
### FreeTierService (`lib/free-tier.ts`)
- Per-tier daily sats budgets (new=0, established=50, trusted=200, elite=1000)
— all env-var overridable
- `decide(pubkey, estimatedSats)` → `{ serve: free|partial|gate, absorbSats, chargeSats }`
— checks pool balance AND identity daily budget atomically
- `credit(paidSats)` — credits POOL_CREDIT_PCT (default 10%) of every paid
work invoice back to the generosity pool
- `recordGrant(pubkey, reqHash, absorbSats)` — DB transaction: deducts pool,
updates identity daily absorption counter, writes audit row
- `poolStatus()` — snapshot for metrics/monitoring
### Route integration
- `POST /api/jobs` (eval → work flow): after eval passes, `freeTierService.decide()`
intercepts. Free → skip invoice, fire work directly. Partial → discounted invoice.
Gate (anonymous/new tier/pool empty) → unchanged full-price flow.
- `POST /api/sessions/:id/request`: after compute, free-tier discount applied to
balance debit. Session balance only reduced by `chargeSats`; absorbed portion
comes from pool.
- Pool credited on every paid work completion (both jobs and session paths).
- Response fields: `free_tier: true`, `absorbed_sats: N` when applicable.
### GET /api/estimate
- Lightweight pre-flight cost estimator; no payment required
- Returns: estimatedSats, btcPriceUsd, tokenEstimate, identity.free_tier decision
(if valid nostr_token provided), pool.balanceSats, pool.dailyBudgets
### Tests
- All 29 existing testkit tests pass (0 failures)
- Anonymous/new-tier users hit gate path correctly (verified manually)
- Pool seeds to 10,000 sats on first boot
## Architecture notes
- Free tier decision happens BEFORE invoice creation for jobs (save user the click)
- Partial grant recorded at invoice creation time (reserves pool capacity proactively)
- Free tier for sessions decided AFTER compute (actual cost known, applied to debit)
- Pool crediting is fire-and-forget (non-blocking)
4c3a0e867a