Integrate Antaeus into my application in shadow mode.

Read https://antaeus.io/hosted-api.md and inspect the application's server-side flow. Ask me for the published policy name, digest and synthetic input shape from my Antaeus dashboard, or for my inline portable policy. Do not invent a reference or policy rules. Ask which application event the policy should review, then map its available fields to the input shape.

I will add ANTAEUS_API_KEY to the deployment's server-side secret store. Never ask for it in chat or put it in frontend code, URLs, logs, source files or Git. Send a server-side POST to https://api.antaeus.io/api/v0.1/decisions with Bearer authentication, Content-Type application/json, a decision.antaeus.io/v0alpha2 DecisionRequest and the exact approved policy reference. Send only the required fields and keep existing authentication and deterministic checks.

Validate the released v0alpha2 Decision schema and handle allow, review, deny and failure explicitly. Completed uncertainty returns review when no matched deny or failed evidence takes precedence. Matched deny wins; failed evidence retains the failure path. An uncertainty review preserves its reason codes and has no failure object. Shadow mode records advisory results while preserving all existing publication, payment and authorization behavior. HTTP errors, timeouts, malformed responses and HTTP 200 failure are not allow. Use a 20-second timeout and one stable Idempotency-Key per logical event, preserving the same key and identical request on bounded retries. Respect Retry-After; never retry other 4xx responses without correction.

Log only the request ID, policy digest, outcome/error and latency. Add tests for each outcome, HTTP failure, timeout and malformed response, plus proof that shadow mode does not change existing behavior. Show me the changes before deployment. After I configure the secret, review and deploy, help me trigger an event and locate its X-Request-Id in Antaeus Usage & requests. Do not enable enforcement without my explicit approval.