Catch breaking API changes

Why API contract drift matters

Understand how an available provider can still break the application that consumes it.

Provider release notes and schema files describe intended behaviour, but production traffic shows the behaviour your integration actually received. A small difference can break mapping, validation, persistence, or downstream decisions without causing a provider outage.

Contract drift is a distinct use case because the team does not need another availability alert. It needs evidence that connects the changed contract path to the integration, environment, release, and observations affected by that change.

When to use this workflow

Choose contract-drift monitoring for externally owned APIs and webhooks.

Use this workflow when your application depends on an API or webhook contract controlled by another team or provider. Seamward observes the operation after it runs, so collection does not replace or proxy the existing request.

• A provider adds, removes, or renames fields used by your mapping.
• A value changes type or a response begins using a different status pattern.
• A webhook event changes shape without an application deployment.
• Latency or acceptance behaviour changes enough to affect the consuming workflow.

Define the expected contract

Identify the stable fields, types, statuses, and latency patterns the integration needs.

Start from the contract the application must preserve, not every field a provider happens to send. Narrow expectations produce findings that an engineer can evaluate without treating harmless additions as incidents.

• Record stable route templates instead of customer-specific URLs.
• Identify required fields and types used by the integration.
• Document accepted status and latency patterns where they affect application behaviour.

Detect the change

Compare redacted production evidence with the contract and baseline your application expects.

The collector records a structural shape, contract fingerprint, operation result, and release context after the existing handler or API call completes. Sensitive values are removed or hashed before the observation is queued for Seamward.

Seamward compares the observed structure with the declared or established expectation. A supported difference becomes a finding tied to the exact path and observation evidence; related findings can then be grouped into an incident.

Review drift findings

Investigate the changed path with its observation, environment, and release context.

Treat a finding as evidence of a change, not automatic proof that the provider caused a customer-visible failure. Compare it with application errors, missing outcomes, and release context before recording a conclusion.

1. Confirm the affected integration, environment, and operation.
2. Compare the previous and observed structure at the reported path.
3. Review the first occurrence and the application release that processed it.
4. Check whether the same observations also produced errors or missing expected outcomes.

Operating boundaries

Keep detection observational and confirm business impact before changing application code.

• Seamward does not sit between the provider and the customer application.
• Collection failure does not replace the application result or provider acknowledgement.
• Raw payload storage is not required for structural drift detection.
• An engineer confirms business impact before approving a repair or provider escalation.

• Drift detectionReview supported changes, baselines, and finding lifecycle.
• RedactionConfigure and verify collector-side data minimisation.