backend-mvp-guardrails

To make backend API writes idempotent, use deterministic keys with upsert or upsert-like guarantees. This ensures duplicate requests or retries do not create conflicting records during rapid schema evolution.

A replayable aggregate is a derived table generated from an immutable source of truth with backfill capabilities. It allows you to rebuild state consistently when schemas evolve or third-party backends recover.

To attribute incidents with third-party backends, implement evidence-first logging and clear fault delimitation. Structured logs provide an auditable trail to isolate whether failures are internal or external.

Additive schema evolution works for MVPs by keeping new fields optional and versioned with allowlists. This approach reduces breaking changes and maintains stability during rapid backend iteration.

The best way to structure an immutable source of truth for backend MVPs is to design an append-only event log. This supports replayable aggregates and enables safe backfill operations during rapid schema evolution.

You should reconsider idempotency keys for backend writes if your MVP lacks a persistent data store to manage deterministic key state. Without storage, upsert-like guarantees cannot be reliably enforced.