diff --git a/web/hwlab-cloud-web/src/stores/workbench-kafka-debug-local-result.test.ts b/web/hwlab-cloud-web/src/stores/workbench-kafka-debug-local-result.test.ts
index b0eeba50..b55369be 100644
--- a/web/hwlab-cloud-web/src/stores/workbench-kafka-debug-local-result.test.ts
+++ b/web/hwlab-cloud-web/src/stores/workbench-kafka-debug-local-result.test.ts
@@ -12,18 +12,42 @@ test("local replay classification reports transport_failed below server delivere
   assert.deepEqual(result.counts, { delivered: 3, clientReceived: 2, decoded: 2, applied: 2 });
 });
 
+test("local replay classification reports transport_failed above server delivered", () => {
+  const result = classifyWorkbenchKafkaDebugLocalResult(terminalResult(3), { clientReceived: 4, decoded: 4, applied: 4 });
+  assert.equal(result.ok, false);
+  assert.equal(result.code, "transport_failed");
+});
+
+test("local replay classification reports contract_invalid when server delivered is missing", () => {
+  const result = classifyWorkbenchKafkaDebugLocalResult(terminalResult(), { clientReceived: 0, decoded: 0, applied: 0 });
+  assert.equal(result.ok, false);
+  assert.equal(result.code, "contract_invalid");
+});
+
 test("local replay classification reports decoder_rejected below client received", () => {
   const result = classifyWorkbenchKafkaDebugLocalResult(terminalResult(3), { clientReceived: 3, decoded: 2, applied: 2 });
   assert.equal(result.ok, false);
   assert.equal(result.code, "decoder_rejected");
 });
 
+test("local replay classification reports decoder_rejected above client received", () => {
+  const result = classifyWorkbenchKafkaDebugLocalResult(terminalResult(3), { clientReceived: 3, decoded: 4, applied: 4 });
+  assert.equal(result.ok, false);
+  assert.equal(result.code, "decoder_rejected");
+});
+
 test("local replay classification reports reducer_rejected below decoded", () => {
   const result = classifyWorkbenchKafkaDebugLocalResult(terminalResult(3), { clientReceived: 3, decoded: 3, applied: 2 });
   assert.equal(result.ok, false);
   assert.equal(result.code, "reducer_rejected");
 });
 
+test("local replay classification reports reducer_rejected above decoded", () => {
+  const result = classifyWorkbenchKafkaDebugLocalResult(terminalResult(3), { clientReceived: 3, decoded: 3, applied: 4 });
+  assert.equal(result.ok, false);
+  assert.equal(result.code, "reducer_rejected");
+});
+
 test("local replay classification preserves terminal_complete when every client stage agrees", () => {
   const result = classifyWorkbenchKafkaDebugLocalResult(terminalResult(3), { clientReceived: 3, decoded: 3, applied: 3 });
   assert.equal(result.ok, true);
@@ -32,13 +56,13 @@ test("local replay classification preserves terminal_complete when every client
   assert.equal(result.localOverlay, true);
 });
 
-function terminalResult(delivered: number): WorkbenchKafkaDebugReplayResult {
+function terminalResult(delivered?: number): WorkbenchKafkaDebugReplayResult {
   return {
     contractVersion: "workbench-kafka-debug-replay-v2",
     ok: true,
     phase: "terminal",
     code: "terminal_complete",
     terminalObserved: true,
-    counts: { delivered, clientReceived: null, decoded: null, applied: null }
+    counts: { ...(delivered === undefined ? {} : { delivered }), clientReceived: null, decoded: null, applied: null }
   };
 }
diff --git a/web/hwlab-cloud-web/src/stores/workbench-kafka-debug-local-result.ts b/web/hwlab-cloud-web/src/stores/workbench-kafka-debug-local-result.ts
index 7e3c0372..9067c47c 100644
--- a/web/hwlab-cloud-web/src/stores/workbench-kafka-debug-local-result.ts
+++ b/web/hwlab-cloud-web/src/stores/workbench-kafka-debug-local-result.ts
@@ -8,7 +8,7 @@ export interface WorkbenchKafkaDebugClientCounts {
   applied: number;
 }
 
-export type WorkbenchKafkaDebugClientFailureCode = "transport_failed" | "decoder_rejected" | "reducer_rejected";
+export type WorkbenchKafkaDebugClientFailureCode = "contract_invalid" | "transport_failed" | "decoder_rejected" | "reducer_rejected";
 
 export function classifyWorkbenchKafkaDebugLocalResult(
   serverResult: WorkbenchKafkaDebugReplayResult,
@@ -19,14 +19,17 @@ export function classifyWorkbenchKafkaDebugLocalResult(
   if (serverResult.code !== "terminal_complete") return overlaid;
 
   const delivered = nonNegativeInteger(serverResult.counts?.delivered);
-  if (delivered !== null && clientCounts.clientReceived < delivered) {
-    return clientFailure(overlaid, "transport_failed", `浏览器收到 ${clientCounts.clientReceived} 条，少于服务端已投递的 ${delivered} 条。`);
+  if (delivered === null) {
+    return clientFailure(overlaid, "contract_invalid", "服务端 terminal_complete 缺少有效的 delivered 计数。");
   }
-  if (clientCounts.decoded < clientCounts.clientReceived) {
-    return clientFailure(overlaid, "decoder_rejected", `浏览器收到 ${clientCounts.clientReceived} 条，但只解码 ${clientCounts.decoded} 条。`);
+  if (clientCounts.clientReceived !== delivered) {
+    return clientFailure(overlaid, "transport_failed", `浏览器收到 ${clientCounts.clientReceived} 条，与服务端已投递的 ${delivered} 条不一致。`);
   }
-  if (clientCounts.applied < clientCounts.decoded) {
-    return clientFailure(overlaid, "reducer_rejected", `浏览器解码 ${clientCounts.decoded} 条，但生产 reducer 只应用 ${clientCounts.applied} 条。`);
+  if (clientCounts.decoded !== clientCounts.clientReceived) {
+    return clientFailure(overlaid, "decoder_rejected", `浏览器收到 ${clientCounts.clientReceived} 条，但解码计数为 ${clientCounts.decoded} 条。`);
+  }
+  if (clientCounts.applied !== clientCounts.decoded) {
+    return clientFailure(overlaid, "reducer_rejected", `浏览器解码 ${clientCounts.decoded} 条，但生产 reducer 应用计数为 ${clientCounts.applied} 条。`);
   }
   return { ...overlaid, ok: true, phase: "terminal", code: "terminal_complete" };
 }