Postcondition verification
A postcondition is a condition that must hold true after an action for that action to count as complete. Postcondition verification is how Postcept turns an agent’s “done” into proof: instead of trusting the claim or the trace, it evaluates each postcondition directly against the system of record.
Why postconditions, not traces
A trace shows what the agent tried to do. A postcondition asks a sharper question: did the world actually end up in the required state? An agent can emit a perfect-looking tool call to issue a refund while the refund silently fails, duplicates, or lands against the wrong charge. Only the system of record can settle it, which is why verification is deterministic, not another model.
The kinds of postconditions
For a high-risk action, Postcept typically evaluates six families of postcondition:
- Existence
- The action exists in the system of record at all (e.g. a Stripe refund object).
- Value match
- Amounts, currency, and identifiers match the agent's claim.
- Identity match
- The customer, account, or subject matches the intended target.
- Status
- The object is in the expected terminal state (succeeded, solved, cancelled).
- Duplicate check
- No second action was created by a retry or lost idempotency key.
- Policy
- Required approvals or verification steps were completed in order.
Worked example: a refund
When a support agent claims refund_customer is done, Postcept evaluates the operation against Stripe and Zendesk. Each postcondition resolves independently to passed, failed, or blocked:
The combined result is sealed into a Postcept Receipt, verified, incomplete, duplicated, mismatched, or policy-failed, and contributes to the agent’s Verified Completion Rate. When a postcondition fails, the operation is routed to review or recovery before the customer is ever notified.
Systems of record Postcept verifies against
The worked example above uses Stripe and Zendesk, but Postcept verifies against a range of payment, commerce, support, and finance systems, read-only, with scoped credentials. Today that includes:
Payments & refunds
Stripe, Adyen, PayPal, Braintree, Square, Shopify, NetSuite, and QuickBooks, checking refund existence, amount, currency, customer, status, and duplicates. Stripe also verifies subscription cancellations.
Support & CRM
Zendesk, Gorgias, Intercom, Front, HubSpot, ServiceNow, and Salesforce, checking ticket, conversation, and case resolution state and requester match.
...and your own internal systems of record via the verification API.
The verification API is live; the full reference and SDKs are coming.
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