fix(web): persist rectification C/D answers on an append-only inference ledger

Engine result rows stay immutable. Choice answers append transitions, and reads overlay the latest revision instead of patching the cached receipt.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/tests/rectification-v9-agent.test.ts

@@ -456,10 +456,26 @@ test("a failed opening does not let the next turn skip the server Skill load gat
 });
 
 test("same evidence + range fingerprints reuse the cached candidate snapshot", async () => {
+  const inputReceipt = {
+    receipt_version: "candidate-decision-receipt-v2",
+    policy_version: "rectification-candidate-policy-v2",
+    selection_allowed: true,
+    acceptance_allowed: true,
+    confirmation_allowed: false,
+    representative_candidate_id: null,
+    overall_confidence: "medium",
+    inference_state: { revision: 1, candidates: [{ id: "05:02", posterior_score: 10 }] },
+  };
+  const composedReceipt = {
+    ...inputReceipt,
+    inference_state: { revision: 2, candidates: [{ id: "05:02", posterior_score: 18 }] },
+    decision_state_fingerprint: "a".repeat(64),
+  };
   const accounting = fakeAccounting({
     persist_agentic_rectification_candidate_v2: () => ({
       ...candidateSnapshotFixture(),
       cached: true,
+      decision_receipt: composedReceipt,
     }),
   });
   const cached = await persistV9Candidate(accounting.client, USER_ID, CASE_ID, {
@@ -472,15 +488,7 @@ test("same evidence + range fingerprints reuse the cached candidate snapshot", a
     eventContractVersion: "rectification-event-contract-v2",
     policyVersion: "rectification-candidate-policy-v2",
     candidates: [{ candidateId: CANDIDATE_ID, rank: 1, time: "05:02", relativeSupport: 58, tiedMinuteCount: 2 }],
-    decisionReceipt: {
-      receipt_version: "candidate-decision-receipt-v2",
-      policy_version: "rectification-candidate-policy-v2",
-      selection_allowed: true,
-      acceptance_allowed: true,
-      confirmation_allowed: false,
-      representative_candidate_id: null,
-      overall_confidence: "medium",
-    },
+    decisionReceipt: inputReceipt,
     executionLedger: [{ method: "d1-rashi", status: "executed" }],
   });
   assert.equal(cached.cached, true);
@@ -491,12 +499,20 @@ test("same evidence + range fingerprints reuse the cached candidate snapshot", a
   assert.equal(call.args.p_skill_version, "9.0.0");
   assert.equal(call.args.p_event_contract_version, "rectification-event-contract-v2");
   assert.equal(call.args.p_decision_policy_version, "rectification-candidate-policy-v2");
-  assert.deepEqual(call.args.p_decision_receipt, cached.decisionReceipt);
+  assert.deepEqual(call.args.p_decision_receipt, inputReceipt);
+  assert.notDeepEqual(cached.decisionReceipt, inputReceipt);
+  assert.deepEqual(cached.decisionReceipt, composedReceipt);
+  assert.equal(
+    (cached.decisionReceipt.inference_state as { revision?: number }).revision,
+    2,
+  );
+  assert.equal(cached.decisionReceipt.decision_state_fingerprint, "a".repeat(64));
   assert.deepEqual(call.args.p_execution_ledger, cached.executionLedger);
   assert.equal("p_selection_allowed" in call.args, false);
   assert.equal("p_confirmation_allowed" in call.args, false);
   assert.equal("p_representative_time" in call.args, false);
   assert.equal("p_margin_percent" in call.args, false);
+  assert.equal("p_decision_state_fingerprint" in call.args, false);
 });
 
 test("accept-candidate requires a server-persisted result; no tool means no minute", async () => {