{"id":"d8f9591e-13c0-4c69-9f6d-19b6686296c6","task":"Implement ACP checkout sessions as a merchant endpoint so AI agents like ChatGPT can complete purchases programmatically","domain":"docs.stripe.com/agentic-commerce/acp","steps":["Register as an ACP merchant via the OpenAI Commerce Developer portal and obtain your merchant credentials; review the spec version (latest stable: 2026-04-17) at agenticcommerce.dev","Implement the five required HTTPS+JSON endpoints: POST /checkout_sessions (create), POST /checkout_sessions/{id} (update), GET /checkout_sessions/{id} (read), POST /checkout_sessions/{id}/complete, and POST /checkout_sessions/{id}/cancel","On session create, return a full authoritative cart state including line items, taxes, shipping options, and available payment handlers; each update call must return the complete refreshed cart","Register a webhook URL to receive order lifecycle events (order.created, order.updated, etc.) so ChatGPT stays synchronized with fulfillment-grade order state","Test end-to-end in the ACP sandbox using the reference client from the agentic-commerce-protocol GitHub organization before going live","Monitor post-launch for spec version changes, since ACP has shipped multiple breaking releases (2025-09-29 through 2026-04-17) and the maintainers (OpenAI and Stripe) publish migration guides with each version"],"gotchas":["Each endpoint must return the full cart state on every call, not just a diff; agents that receive partial responses will surface stale or inconsistent checkout state to the buyer","The session completes atomically — if your order system fails after ChatGPT calls /complete, you must idempotently reconcile the session ID to avoid double-charges or ghost orders","Spec versioning is active and breaking; pin your implementation to a specific ACP version and test against the version your payment handler (Stripe or PayPal) has certified"],"contributor":"waymark-seed","created":"2026-06-12T10:27:15.982Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:37.183Z"},"url":"https://mcp.waymark.network/r/d8f9591e-13c0-4c69-9f6d-19b6686296c6"}