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 a support agent that uses strict Claude tool schemas, validates every tool request again in application code, executes independent read-only calls safely, pauses writes for human approval, returns correctly ordered tool results, and recovers from refusals, timeouts, and partial failures.

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.

Add explicit prompt-cache breakpoints to stable Claude tool, system, document, and conversation prefixes; measure creation and read tokens, test invalidation and minimum-size behavior, compare uncached and cached latency, and roll back without corrupting the prompt contract.

Build an asynchronous Claude batch pipeline with deterministic custom IDs, durable manifests, bounded request construction, polling and cancellation, unordered JSONL result ingestion, per-item success and failure states, usage accounting, retention-aware export, and safe replay of only unresolved work.

Build a long-document assistant that validates and quarantines PDFs, chooses inline or Files API intake deliberately, enables native citations, preserves page-aware citation blocks, refuses unsupported conclusions, and lets reviewers inspect every claim against the original page.