curl "http://localhost:8000/api/v2/agents/my-agent/policy/presets/balanced" \
  -H "X-Session-Token: your_session_token"

{
  "name": "balanced",
  "description": "Sensible defaults for a working agent: transient state ages out in weeks, semantic knowledge in months, durable truths never.",
  "policy": {
    "version": 1,
    "retention": {
      "context": "7d",
      "event": "30d",
      "error": "30d",
      "observation": "60d",
      "commitment": "90d",
      "artifact": "180d"
    },
    "rules": [
      { "name": "pinned", "match": { "tags": ["pinned"] }, "expire_after": "never" },
      { "name": "scratch-notes", "match": { "tags": ["scratch", "temp"] }, "expire_after": "3d" },
      {
        "name": "low-confidence-guesses",
        "match": { "provenance": ["inferred"], "confidence_below": 0.5 },
        "expire_after": "14d"
      }
    ],
    "purge_expired_after": "never"
  }
}

{
  "detail": "Unknown preset 'nope'. Must be one of: aggressive, balanced, conservative."
}

{
  "detail": "Missing session token. Use X-Session-Token header."
}