Add RedactionTombstone schema

Author: mdheller

schemas/RedactionTombstone.json

@@ -0,0 +1,35 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://schemas.srcos.ai/v2/RedactionTombstone.json",
+  "title": "RedactionTombstone",
+  "description": "Governance event requiring invalidation or suppression of previously propagated OpsHistory, memory, artifact, or context-pack material.",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["tombstoneId", "specVersion", "issuedAt", "issuerRef", "targetRefs", "reasonClass", "priority", "policyDecisionRefs"],
+  "properties": {
+    "tombstoneId": { "type": "string", "pattern": "^urn:srcos:redaction-tombstone:" },
+    "specVersion": { "type": "string" },
+    "issuedAt": { "type": "string", "format": "date-time" },
+    "issuerRef": { "type": "string" },
+    "targetRefs": { "type": "array", "minItems": 1, "items": { "type": "string" } },
+    "reasonClass": {
+      "type": "string",
+      "enum": ["user-request", "policy-violation", "credential-exposure", "sensitive-context", "retention-expiry", "legal-hold-exception", "operator-correction"]
+    },
+    "priority": { "type": "string", "enum": ["high", "critical"] },
+    "propagation": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "targetPropagationSeconds": { "type": "integer", "minimum": 0 },
+        "invalidateContextPacks": { "type": "boolean" },
+        "invalidateMemoryWritebacks": { "type": "boolean" },
+        "invalidateArtifactExports": { "type": "boolean" },
+        "notifyAgents": { "type": "boolean" }
+      }
+    },
+    "replacementRef": { "type": ["string", "null"] },
+    "policyDecisionRefs": { "type": "array", "items": { "type": "string" } },
+    "evidenceRefs": { "type": "array", "items": { "type": "string" }, "default": [] }
+  }
+}