{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://genai-security-project.github.io/agent-control-standard/schema/v0.1.0/hooks/skill-unload.json",
  "title": "steps/skillUnload payload",
  "description": "Fires when a skill leaves the active set. Its enforcement value is low: by unload time the skill's actions have already run, so a Guardian typically observes rather than denies. It earns a place for two reasons: it keeps the AgBOM's active inventory accurate, and repeated load/unload churn of the same skill is itself an evasion signal worth tracing. Deployments MAY fold this into agbom/changed instead of emitting a distinct hook; the field shape below is what agbom/changed would carry for a skill removal.",
  "type": "object",
  "required": ["skill_id", "reason"],
  "properties": {
    "skill_id": {
      "type": "string",
      "description": "Id of the skill being unloaded. References the 'skill' component."
    },
    "reason": {
      "type": "string",
      "enum": ["session_end", "explicit_unload", "replaced", "error"],
      "description": "Why the skill left the active set. 'replaced' means a different version or skill took its place. Pair with the replacing skill_id in load events to trace swaps."
    },
    "replaced_by": {
      "type": "string",
      "description": "When reason='replaced', the skill_id that took this skill's place."
    }
  }
}