Add llm-assisted discovery extraction

schemas/discovery-snapshot.schema.yaml

@@ -97,6 +97,10 @@ properties:
     type: array
     items:
       $ref: "#/$defs/tombstone"
+  review_artifacts:
+    type: array
+    items:
+      $ref: "#/$defs/reviewArtifact"
   reconciliation:
     type: object
     additionalProperties: false
@@ -485,3 +489,39 @@ $defs:
       previous_candidate:
         type: object
         additionalProperties: true
+
+  reviewArtifact:
+    type: object
+    additionalProperties: false
+    required:
+      - id
+      - artifact_type
+      - origin
+      - message
+      - created_at
+    properties:
+      id:
+        $ref: "#/$defs/stableKey"
+      artifact_type:
+        type: string
+        enum:
+          - llm_output_invalid
+          - llm_low_confidence
+          - llm_candidate_unresolved
+          - llm_execution_error
+      origin:
+        $ref: "#/$defs/origin"
+      message:
+        type: string
+        minLength: 1
+      evidence_refs:
+        type: array
+        items:
+          type: string
+          minLength: 1
+      payload:
+        type: object
+        additionalProperties: true
+      created_at:
+        type: string
+        format: date-time