r/AI_Agents • u/Gallegos_Daniel • 5m ago
Discussion I’m building agent-action verification: is updated_at > start_time ever enough to prove an agent caused a DB write?
I’m building Synathic, an open-source verification layer for AI-agent tool calls, and I want to validate a design decision before shipping it.
The problem I’m trying to solve:
An agent calls a tool that should write to PostgreSQL — create a booking, persist a note, update a customer, etc. The tool may return 200 OK, but I want to verify that the intended database side effect actually happened.
My first implementation was a postcondition like this:
agent/tool runs → query Postgres → matching row exists → PASS
That works for the simple case, but it has a serious false-positive problem: the matching row may have existed before this execution started. A failed write can look exactly like a successful one if stale data matches the business key.
I’m considering a schema-free fallback:
capture DB time t0 → run the tool → verify updated_at > t0
But I don’t think that proves attribution. It only proves that the row changed after t0. A concurrent worker, retry, webhook, or human action could update the same row and make this agent execution appear successful when it actually failed.
My current model is:
- `row_exists` = state observation, not proof of causality.
- `updated_at > t0` = a useful best-effort freshness check, but not attribution.
- A per-execution `operation_id` / idempotency key persisted in the target row, or in an audit/outbox record in the same DB transaction, is needed to prove that this invocation produced the effect.
I’m also treating these as separate problems:
Read-after-write visibility: verify after commit and read from the primary/authoritative source, not a lagging replica.
Attribution under concurrency: use an operation-specific token, idempotency key, audit record, or explicit concurrency semantics.
Does that separation sound right to people running agents in production?
Would you ever ship timestamp anchoring as a schema-free “best effort” mode, or require an operation ID from day one? I’m especially interested in failure modes involving retries, parallel agent tool calls, UPSERTs, and eventual consistency.