Initial import

packages/domain/README.md

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+# packages/domain
+
+Business rules for `nproxy`.
+
+## Implemented in this iteration
+- Approximate quota bucket contract: `100/80/60/40/20/0`
+- Provider key pool round-robin active-key selection
+- Provider attempt classification for retry vs terminal outcomes
+- Key-state transition policy for cooldown/manual_review/out_of_funds
+
+## Current exports
+- `getApproximateQuotaBucket`
+- `isRetryableFailure`
+- `evaluateAttempt`
+- `selectActiveKeysRoundRobin`
+- `buildAttemptPlan`
+
+## Notes
+- Domain logic stays provider-agnostic.
+- Transport code must live in `packages/providers`.