An AI agent audit trail retention policy decides which records about agent actions you keep, for how long, in what form, and when they are deleted. The goal is to prove what an agent did and who authorized it, without turning every prompt and tool payload into a permanent copy of sensitive data.
The risk is real. OpenTelemetry's generative AI conventions warn that message content "is likely to contain sensitive information including user/PII data" (OpenTelemetry GenAI attributes). Keeping it by default, forever, is the most common retention mistake.
Audit retention should preserve accountability without turning prompts and tool payloads into a permanent shadow database. Classify evidence by purpose, sensitivity, jurisdiction, and reconstructive value.
Retention tiers
| Tier | Examples | Policy |
|---|---|---|
| Decision record | Identity, policy, action, approval, result, outcome | Durable, integrity-protected, exportable |
| Operational telemetry | Latency, tokens, retries, health, errors | Shorter operational window with aggregation |
| Sensitive content | Prompts, retrieved text, tool arguments and results | Opt-in, minimal, separately encrypted and access-controlled |
| Secrets | Bearer tokens, API keys, private credentials | Never intentionally capture; detect and purge |
Write the schedule
For every field define purpose, owner, lawful or contractual basis, default duration, deletion trigger, legal-hold behavior, storage region, access roles, and export format. Preserve hashes or immutable references when the source record may remain in its system of record.
Durations come from your legal, contractual and regulatory obligations, not from the logging tool's default. Write the reason next to each duration so the next reviewer can tell a requirement from a habit.
Keep the decision, reduce the content
Most reconstructions need to know that an action happened, under which policy version, with whose approval, and with what result. They rarely need the full prompt. Store a hash or a reference to the source record, and keep the full content only where a specific review or dispute process needs it.
Legal holds
A legal hold pauses deletion for named records. Apply it by case, not by turning off deletion for everything, and record who placed the hold, when, and when it was released.
Deletion test
Delete one user, workspace, and expired tenant in a non-production environment. Verify primary stores, search indexes, caches, analytics copies, backups, exports, and subprocessors follow the documented policy while required audit evidence remains intelligible and appropriately pseudonymized.
Common mistakes
- Capturing full prompts and tool results by default in traces.
- Letting secrets reach logs, then keeping the logs.
- Deleting decision records together with the sensitive content they point to.
- Forgetting backups, exports and analytics copies in the deletion plan.
Apply the retention schedule to the BlueBear audit evidence contract. For what the trail must capture in the first place, see what an AI agent audit trail is.