Scope shadow receipt identities to each retry

src/value-receipt.js

@@ -1,3 +1,5 @@
+import { contentIdentity } from './canonical.js';
+
 const RECEIPT_SCHEMA = 'opsle.value-receipt.v1';
 
 function measurement({ id, baseline, result, delta, unit, direction, operatorDisplay, limitation = [] }) {
@@ -173,7 +175,12 @@ export function buildShadowValueReceipt(plan, shadow, {
       work_classification: 'DETERMINISTIC_VERIFICATION_SHADOW',
     },
     operation: {
-      id: shadow.observation_identity,
+      // The observation identity deliberately stays stable when the same plan
+      // and results are reproduced. A receipt operation is one execution of
+      // that observation, so include its execution generation to keep retries
+      // distinct within the same Visible Value run.
+      id: contentIdentity({ execution_id: executionId, generation,
+        observation_identity: shadow.observation_identity }),
       name: 'verification-shadow',
       configuration_id: plan.provenance.verification_catalog_identity,
       policy_id: plan.provenance.policy_identity,

tests/tasks-capability.test.js

@@ -139,6 +139,13 @@ test('installable artifact contains planner and schemas, plans deterministically
     result.value.decision.plan.plan_identity);
   const repeat = adapter.invoke('verification.plan', { ...request(f), generation: 2 });
   assert.deepEqual(repeat.value.decision, result.value.decision);
+  const repeatedShadow = adapter.invoke('verification.shadow',
+    shadowRequest(f, repeat.value.decision.plan, { generation: 2 }));
+  assert.equal(repeatedShadow.value.shadow.observation_identity,
+    finalized.value.shadow.observation_identity,
+    'the same plan and results retain their content identity');
+  assert.notEqual(repeatedShadow.receipts[0].operation.id, receipt.operation.id,
+    'each execution generation has a distinct receipt operation');
   const capture = () => adapter.invoke('verification.capture', { schema: 'opsle.execution.change-capture-request.v1', task: f.task }).value;
   assert.equal(capture().target_revision, result.value.change.target_revision);
   writeFileSync(resolve(f.task.repo_path, 'a.js'), 'drift\n');