12.5 Audit trails: saving prompts and outputs safely

Overview and links for this section of the guide.

Why audit trails matter

Audit trails answer: “What happened, with what inputs, under what rules, and why did we get this output?”

They matter because:

  • you need to debug failures and regressions,
  • you need to explain behavior to users and stakeholders,
  • you need to track prompt/model changes like code changes,
  • you need accountability for tool usage and outputs.
Audit trails are part of reliability

When something goes wrong, an audit trail turns “mystery” into “investigation.” That’s how teams improve instead of repeating incidents.

What to store (and what not to)

Store enough to reproduce and diagnose, without storing sensitive content unnecessarily.

Good things to store

  • timestamp, request id, user/session id (or anonymized id)
  • model name/version and key settings
  • prompt version id (not necessarily the full prompt text)
  • input/output sizes, latency, retry counts
  • outcome category (ok/blocked/timeout/invalid_output)
  • tool calls made (names + parameters redacted as needed)
  • validation results (schema pass/fail)

Things to avoid storing by default

  • raw user inputs containing PII or confidential docs
  • raw prompts with embedded secrets
  • raw model outputs that contain sensitive data
“Just log everything” is unsafe

It creates a permanent sensitive dataset. Prefer metadata + versions + redacted samples with strict access controls.

A minimal audit record (fields)

audit_record:
- request_id
- timestamp
- user_id (or anonymized)
- model
- model_settings (temperature, max_output, etc.)
- prompt_version
- input_size / token_estimate
- output_size / token_estimate
- latency_ms
- retries_attempted
- outcome_category (ok/blocked/timeout/invalid_output/unknown)
- safety_category (if available)
- schema_validation (pass/fail + errors)
- tools_used (names + redacted params)

Privacy-safe audit trails

Practical safety measures:

  • redact sensitive fields at ingestion,
  • encrypt at rest,
  • restrict access (least privilege),
  • set retention limits,
  • make “full content logging” an explicit, temporary debug mode.

Workflows: prompts as artifacts

For vibe coding teams, a powerful workflow is:

  • store prompts as files in your repo,
  • version them,
  • review prompt diffs,
  • tie prompt versions to releases and evaluations.

This makes AI behavior change management look like normal software change management.

Where to go next