Public REST API: Full public availability of /v1/links, /v1/me, and analytics endpoints.

Token-Bucket Rate Limiting: Transitioned from fixed-window rate limiting to continuous Redis token-bucket replenishment with burst capacity.

Typed Error Contracts: Replaced ambiguous retryAfter with authoritative retryAfterSeconds across API responses and SDK exceptions.

Permanent Tombstones: Implemented reserved_codes registry to prevent short code recycling attacks.

OpenAPI 3.1 Spec: Complete machine-readable OpenAPI definitions in JSON and YAML formats.

Interactive Documentation: Added 3-column developer documentation portal with client-side API playground and ephemeral key testing.