Complete procedures with a way back.

Build a runnable native OpenAI Responses and Claude Messages router for an explicitly limited non-streaming text contract, with strict unsupported-feature rejection, provider-specific adapters, durable turn idempotency, native evidence, sanitized errors, timeout reconciliation, live parity fixtures, tenant canaries, and rollback without replay.

Build an authenticated Claude chat service that persists application-owned conversation turns, streams typed content blocks, distinguishes every stop reason, handles cancellation and browser reconnection, and never duplicates a model turn after an ambiguous disconnect.