diff --git a/.changeset/record-model-response-id.md b/.changeset/record-model-response-id.md
new file mode 100644
index 000000000..22df140f7
--- /dev/null
+++ b/.changeset/record-model-response-id.md
@@ -0,0 +1,7 @@
+---
+"@moonshot-ai/kimi-code": patch
+"@moonshot-ai/kimi-code-sdk": patch
+"@moonshot-ai/agent-core": patch
+---
+
+Record model response ids in session wire logs to make individual model requests easier to trace.
diff --git a/packages/agent-core/src/agent/turn/kosong-llm.ts b/packages/agent-core/src/agent/turn/kosong-llm.ts
index d5812cf03..2e0e4beea 100644
--- a/packages/agent-core/src/agent/turn/kosong-llm.ts
+++ b/packages/agent-core/src/agent/turn/kosong-llm.ts
@@ -151,6 +151,7 @@ export class KosongLLM implements LLM {
       toolCalls: [...result.message.toolCalls],
       providerFinishReason: result.finishReason ?? undefined,
       rawFinishReason: result.rawFinishReason ?? undefined,
+      messageId: result.id ?? undefined,
       usage: result.usage ?? emptyUsage(),
       streamTiming:
         firstChunkAt === undefined
diff --git a/packages/agent-core/src/loop/events.ts b/packages/agent-core/src/loop/events.ts
index 786afb574..62d4c65a9 100644
--- a/packages/agent-core/src/loop/events.ts
+++ b/packages/agent-core/src/loop/events.ts
@@ -41,6 +41,7 @@ export interface LoopStepEndEvent {
    */
   readonly providerFinishReason?: FinishReason | undefined;
   readonly rawFinishReason?: string | undefined;
+  readonly messageId?: string | undefined;
 }
 
 export interface LoopStepRetryingEvent {
diff --git a/packages/agent-core/src/loop/llm.ts b/packages/agent-core/src/loop/llm.ts
index 065030623..9d58dce7c 100644
--- a/packages/agent-core/src/loop/llm.ts
+++ b/packages/agent-core/src/loop/llm.ts
@@ -82,6 +82,7 @@ export interface LLMChatResponse {
   toolCalls: ToolCall[];
   providerFinishReason?: FinishReason;
   rawFinishReason?: string;
+  messageId?: string;
   usage: TokenUsage;
   streamTiming?: LLMStreamTiming;
 }
diff --git a/packages/agent-core/src/loop/turn-step.ts b/packages/agent-core/src/loop/turn-step.ts
index 8d72cad5d..1de563354 100644
--- a/packages/agent-core/src/loop/turn-step.ts
+++ b/packages/agent-core/src/loop/turn-step.ts
@@ -196,6 +196,7 @@ export async function executeLoopStep(deps: ExecuteLoopStepDeps): Promise<{
     llmServerFirstTokenMs: response.streamTiming?.serverFirstTokenMs,
     llmServerDecodeMs: response.streamTiming?.serverDecodeMs,
     llmClientConsumeMs: response.streamTiming?.clientConsumeMs,
+    messageId: response.messageId,
     ...stepEndProviderDiagnostics(response, effectiveStopReason),
   });
 
diff --git a/packages/agent-core/test/agent/basic.test.ts b/packages/agent-core/test/agent/basic.test.ts
index f034effd5..f7b73da4f 100644
--- a/packages/agent-core/test/agent/basic.test.ts
+++ b/packages/agent-core/test/agent/basic.test.ts
@@ -31,7 +31,7 @@ it('runs a text-only agent turn from prompt to completion', async () => {
     [emit] assistant.delta             { "turnId": 0, "delta": "<text-1>" }
     [wire] context.append_loop_event   { "event": { "type": "content.part", "uuid": "<uuid-2>", "turnId": "0", "step": 1, "stepUuid": "<uuid-1>", "part": { "type": "think", "think": "<think-1>" } }, "time": "<time>" }
     [wire] context.append_loop_event   { "event": { "type": "content.part", "uuid": "<uuid-3>", "turnId": "0", "step": 1, "stepUuid": "<uuid-1>", "part": { "type": "text", "text": "<text-1>" } }, "time": "<time>" }
-    [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 3, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+    [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 3, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-1" }, "time": "<time>" }
     [emit] turn.step.completed         { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 3, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
     [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 3, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
     [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 11, "maxContextTokens": 1000000, "contextUsage": 0.000011, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 3, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 3, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 3, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -124,7 +124,7 @@ it('runs an agent turn through builtin tool approval and execution', async () =>
     [emit] tool.progress                       { "turnId": 0, "toolCallId": "call_bash", "update": { "kind": "stdout", "text": "lookup-result" } }
     [wire] context.append_loop_event           { "event": { "type": "tool.result", "parentUuid": "call_bash", "toolCallId": "call_bash", "result": { "output": "lookup-result" } }, "time": "<time>" }
     [emit] tool.result                         { "turnId": 0, "toolCallId": "call_bash", "output": "lookup-result" }
-    [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 11, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }, "time": "<time>" }
+    [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 11, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use", "messageId": "mock-1" }, "time": "<time>" }
     [emit] turn.step.completed                 { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 11, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }
     [wire] usage.record                        { "model": "mock-model", "usage": { "inputOther": 11, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
     [emit] agent.status.updated                { "model": "mock-model", "contextTokens": 33, "maxContextTokens": 1000000, "contextUsage": 0.000033, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 11, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 11, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 11, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -132,7 +132,7 @@ it('runs an agent turn through builtin tool approval and execution', async () =>
     [emit] turn.step.started                   { "turnId": 0, "step": 2, "stepId": "<uuid-3>" }
     [emit] assistant.delta                     { "turnId": 0, "delta": "The command printed lookup-result." }
     [wire] context.append_loop_event           { "event": { "type": "content.part", "uuid": "<uuid-4>", "turnId": "0", "step": 2, "stepUuid": "<uuid-3>", "part": { "type": "text", "text": "The command printed lookup-result." } }, "time": "<time>" }
-    [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 38, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+    [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 38, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-2" }, "time": "<time>" }
     [emit] turn.step.completed                 { "turnId": 0, "step": 2, "stepId": "<uuid-3>", "usage": { "inputOther": 38, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
     [wire] usage.record                        { "model": "mock-model", "usage": { "inputOther": 38, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
     [emit] agent.status.updated                { "model": "mock-model", "contextTokens": 50, "maxContextTokens": 1000000, "contextUsage": 0.00005, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 49, "output": 34, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 49, "output": 34, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 49, "output": 34, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
diff --git a/packages/agent-core/test/agent/compaction/full.test.ts b/packages/agent-core/test/agent/compaction/full.test.ts
index cdd0567ea..0892ad0b0 100644
--- a/packages/agent-core/test/agent/compaction/full.test.ts
+++ b/packages/agent-core/test/agent/compaction/full.test.ts
@@ -1148,7 +1148,7 @@ describe('FullCompaction', () => {
       [emit] turn.step.started           { "turnId": 0, "step": 1, "stepId": "<uuid-1>" }
       [emit] assistant.delta             { "turnId": 0, "delta": "I can answer after compaction." }
       [wire] context.append_loop_event   { "event": { "type": "content.part", "uuid": "<uuid-2>", "turnId": "0", "step": 1, "stepUuid": "<uuid-1>", "part": { "type": "text", "text": "I can answer after compaction." } }, "time": "<time>" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 165, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 165, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-2" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 165, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                { "model": "kimi-code", "usage": { "inputOther": 165, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "kimi-code", "contextTokens": 176, "maxContextTokens": 256000, "contextUsage": 0.0006875, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "kimi-code": { "inputOther": 1338, "output": 20, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 1338, "output": 20, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 165, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -2190,7 +2190,7 @@ describe('FullCompaction', () => {
       [emit] tool.call.started           { "turnId": 0, "toolCallId": "call_missing", "name": "MissingTool", "args": {} }
       [wire] context.append_loop_event   { "event": { "type": "tool.result", "parentUuid": "call_missing", "toolCallId": "call_missing", "result": { "output": "Tool \\"MissingTool\\" not found", "isError": true } }, "time": "<time>" }
       [emit] tool.result                 { "turnId": 0, "toolCallId": "call_missing", "output": "Tool \\"MissingTool\\" not found", "isError": true }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 154, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 154, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use", "messageId": "mock-2" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 154, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 154, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 165, "maxContextTokens": 1000000, "contextUsage": 0.000165, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 1289, "output": 20, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 1289, "output": 20, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 154, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
diff --git a/packages/agent-core/test/agent/config.test.ts b/packages/agent-core/test/agent/config.test.ts
index 3066481bf..e4e562489 100644
--- a/packages/agent-core/test/agent/config.test.ts
+++ b/packages/agent-core/test/agent/config.test.ts
@@ -172,7 +172,7 @@ describe('Agent config', () => {
       [emit] tool.progress                       { "turnId": 0, "toolCallId": "call_bash", "update": { "kind": "stdout", "text": "original-result" } }
       [wire] context.append_loop_event           { "event": { "type": "tool.result", "parentUuid": "call_bash", "toolCallId": "call_bash", "result": { "output": "original-result" } }, "time": "<time>" }
       [emit] tool.result                         { "turnId": 0, "toolCallId": "call_bash", "output": "original-result" }
-      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 9, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }, "time": "<time>" }
+      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 9, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use", "messageId": "mock-1" }, "time": "<time>" }
       [emit] turn.step.completed                 { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 9, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }
       [wire] usage.record                        { "model": "mock-model", "usage": { "inputOther": 9, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated                { "model": "changed-model", "contextTokens": 32, "maxContextTokens": 1000000, "contextUsage": 0.000032, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 9, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 9, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 9, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -180,7 +180,7 @@ describe('Agent config', () => {
       [emit] turn.step.started                   { "turnId": 0, "step": 2, "stepId": "<uuid-3>" }
       [emit] assistant.delta                     { "turnId": 0, "delta": "Still using the original turn config." }
       [wire] context.append_loop_event           { "event": { "type": "content.part", "uuid": "<uuid-4>", "turnId": "0", "step": 2, "stepUuid": "<uuid-3>", "part": { "type": "text", "text": "Still using the original turn config." } }, "time": "<time>" }
-      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 37, "output": 13, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 37, "output": 13, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-2" }, "time": "<time>" }
       [emit] turn.step.completed                 { "turnId": 0, "step": 2, "stepId": "<uuid-3>", "usage": { "inputOther": 37, "output": 13, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                        { "model": "mock-model", "usage": { "inputOther": 37, "output": 13, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated                { "model": "changed-model", "contextTokens": 50, "maxContextTokens": 1000000, "contextUsage": 0.00005, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 46, "output": 36, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 46, "output": 36, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 46, "output": 36, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -204,7 +204,7 @@ describe('Agent config', () => {
       [emit] turn.step.started           { "turnId": 1, "step": 1, "stepId": "<uuid-5>" }
       [emit] assistant.delta             { "turnId": 1, "delta": "Now the changed config is active." }
       [wire] context.append_loop_event   { "event": { "type": "content.part", "uuid": "<uuid-6>", "turnId": "1", "step": 1, "stepUuid": "<uuid-5>", "part": { "type": "text", "text": "Now the changed config is active." } }, "time": "<time>" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-5>", "turnId": "1", "step": 1, "usage": { "inputOther": 56, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-5>", "turnId": "1", "step": 1, "usage": { "inputOther": 56, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-3" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 1, "step": 1, "stepId": "<uuid-5>", "usage": { "inputOther": 56, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                { "model": "changed-model", "usage": { "inputOther": 56, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "changed-model", "contextTokens": 68, "maxContextTokens": 1000000, "contextUsage": 0.000068, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 46, "output": 36, "inputCacheRead": 0, "inputCacheCreation": 0 }, "changed-model": { "inputOther": 56, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 102, "output": 48, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 56, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
diff --git a/packages/agent-core/test/agent/kosong-llm.test.ts b/packages/agent-core/test/agent/kosong-llm.test.ts
index ffb80edb3..eee338809 100644
--- a/packages/agent-core/test/agent/kosong-llm.test.ts
+++ b/packages/agent-core/test/agent/kosong-llm.test.ts
@@ -90,6 +90,27 @@ describe('KosongLLM streaming tool-call deltas', () => {
   });
 });
 
+describe('KosongLLM response id', () => {
+  it('surfaces the provider response id from the generate result', async () => {
+    const generate: GenerateFn = async () => ({
+      id: 'chatcmpl-test',
+      message: { role: 'assistant', content: [], toolCalls: [] },
+      usage: emptyUsage(),
+      finishReason: 'completed',
+      rawFinishReason: 'stop',
+    });
+    const llm = new KosongLLM({ provider, systemPrompt: 'system', generate });
+
+    const response = await llm.chat({
+      messages: [],
+      tools: [],
+      signal: new AbortController().signal,
+    });
+
+    expect(response.messageId).toBe('chatcmpl-test');
+  });
+});
+
 describe('KosongLLM stream timing', () => {
   it('returns timing measured from provider request start to stream end', async () => {
     const generate: GenerateFn = async (
diff --git a/packages/agent-core/test/agent/permission.test.ts b/packages/agent-core/test/agent/permission.test.ts
index 5321b26ba..094bd8d8c 100644
--- a/packages/agent-core/test/agent/permission.test.ts
+++ b/packages/agent-core/test/agent/permission.test.ts
@@ -61,7 +61,7 @@ describe('Agent permission', () => {
       [emit] tool.progress               { "turnId": 0, "toolCallId": "call_bash", "update": { "kind": "stdout", "text": "auto-output" } }
       [wire] context.append_loop_event   { "event": { "type": "tool.result", "parentUuid": "call_bash", "toolCallId": "call_bash", "result": { "output": "auto-output" } }, "time": "<time>" }
       [emit] tool.result                 { "turnId": 0, "toolCallId": "call_bash", "output": "auto-output" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 91, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 91, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use", "messageId": "mock-1" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 91, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 91, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 116, "maxContextTokens": 1000000, "contextUsage": 0.000116, "planMode": false, "swarmMode": false, "permission": "auto", "usage": { "byModel": { "mock-model": { "inputOther": 91, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 91, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 91, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -69,7 +69,7 @@ describe('Agent permission', () => {
       [emit] turn.step.started           { "turnId": 0, "step": 2, "stepId": "<uuid-3>" }
       [emit] assistant.delta             { "turnId": 0, "delta": "The command printed auto-output." }
       [wire] context.append_loop_event   { "event": { "type": "content.part", "uuid": "<uuid-4>", "turnId": "0", "step": 2, "stepUuid": "<uuid-3>", "part": { "type": "text", "text": "The command printed auto-output." } }, "time": "<time>" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 120, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 120, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-2" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 2, "stepId": "<uuid-3>", "usage": { "inputOther": 120, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 120, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 131, "maxContextTokens": 1000000, "contextUsage": 0.000131, "planMode": false, "swarmMode": false, "permission": "auto", "usage": { "byModel": { "mock-model": { "inputOther": 211, "output": 36, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 211, "output": 36, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 211, "output": 36, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -117,7 +117,7 @@ describe('Agent permission', () => {
       [emit] tool.progress               { "turnId": 0, "toolCallId": "call_bash", "update": { "kind": "stdout", "text": "yolo-output" } }
       [wire] context.append_loop_event   { "event": { "type": "tool.result", "parentUuid": "call_bash", "toolCallId": "call_bash", "result": { "output": "yolo-output" } }, "time": "<time>" }
       [emit] tool.result                 { "turnId": 0, "toolCallId": "call_bash", "output": "yolo-output" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 7, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 7, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use", "messageId": "mock-1" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 7, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 7, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 32, "maxContextTokens": 1000000, "contextUsage": 0.000032, "planMode": false, "swarmMode": false, "permission": "yolo", "usage": { "byModel": { "mock-model": { "inputOther": 7, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 7, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 7, "output": 25, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -125,7 +125,7 @@ describe('Agent permission', () => {
       [emit] turn.step.started           { "turnId": 0, "step": 2, "stepId": "<uuid-3>" }
       [emit] assistant.delta             { "turnId": 0, "delta": "The command printed yolo-output." }
       [wire] context.append_loop_event   { "event": { "type": "content.part", "uuid": "<uuid-4>", "turnId": "0", "step": 2, "stepUuid": "<uuid-3>", "part": { "type": "text", "text": "The command printed yolo-output." } }, "time": "<time>" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 36, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 36, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-2" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 2, "stepId": "<uuid-3>", "usage": { "inputOther": 36, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 36, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 47, "maxContextTokens": 1000000, "contextUsage": 0.000047, "planMode": false, "swarmMode": false, "permission": "yolo", "usage": { "byModel": { "mock-model": { "inputOther": 43, "output": 36, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 43, "output": 36, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 43, "output": 36, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -170,7 +170,7 @@ describe('Agent permission', () => {
       [emit] turn.step.started           { "turnId": 1, "step": 1, "stepId": "<uuid-3>" }
       [emit] assistant.delta             { "turnId": 1, "delta": "Manual turn done." }
       [wire] context.append_loop_event   { "event": { "type": "content.part", "uuid": "<uuid-4>", "turnId": "1", "step": 1, "stepUuid": "<uuid-3>", "part": { "type": "text", "text": "Manual turn done." } }, "time": "<time>" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "1", "step": 1, "usage": { "inputOther": 161, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "1", "step": 1, "usage": { "inputOther": 161, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-2" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 1, "step": 1, "stepId": "<uuid-3>", "usage": { "inputOther": 161, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 161, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 169, "maxContextTokens": 1000000, "contextUsage": 0.000169, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 250, "output": 15, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 250, "output": 15, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 161, "output": 8, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -234,7 +234,7 @@ describe('Agent permission', () => {
       [emit] tool.call.started                   { "turnId": 0, "toolCallId": "call_bash", "name": "Bash", "args": { "command": "printf should-not-run", "timeout": 60 }, "description": "Running: printf should-not-run", "display": { "kind": "command", "command": "printf should-not-run", "cwd": "<cwd>", "language": "bash" } }
       [wire] context.append_loop_event           { "event": { "type": "tool.result", "parentUuid": "call_bash", "toolCallId": "call_bash", "result": { "output": "Tool \\"Bash\\" was not run because the user rejected the approval request. Do not re-attempt the exact same call — think about why it was rejected, then adjust your approach or ask the user what they would prefer.", "isError": true } }, "time": "<time>" }
       [emit] tool.result                         { "turnId": 0, "toolCallId": "call_bash", "output": "Tool \\"Bash\\" was not run because the user rejected the approval request. Do not re-attempt the exact same call — think about why it was rejected, then adjust your approach or ask the user what they would prefer.", "isError": true }
-      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 5, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }, "time": "<time>" }
+      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 5, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use", "messageId": "mock-1" }, "time": "<time>" }
       [emit] turn.step.completed                 { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 5, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }
       [wire] usage.record                        { "model": "mock-model", "usage": { "inputOther": 5, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated                { "model": "mock-model", "contextTokens": 27, "maxContextTokens": 1000000, "contextUsage": 0.000027, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 5, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 5, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 5, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -242,7 +242,7 @@ describe('Agent permission', () => {
       [emit] turn.step.started                   { "turnId": 0, "step": 2, "stepId": "<uuid-3>" }
       [emit] assistant.delta                     { "turnId": 0, "delta": "I will not run the command." }
       [wire] context.append_loop_event           { "event": { "type": "content.part", "uuid": "<uuid-4>", "turnId": "0", "step": 2, "stepUuid": "<uuid-3>", "part": { "type": "text", "text": "I will not run the command." } }, "time": "<time>" }
-      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 93, "output": 10, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 93, "output": 10, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-2" }, "time": "<time>" }
       [emit] turn.step.completed                 { "turnId": 0, "step": 2, "stepId": "<uuid-3>", "usage": { "inputOther": 93, "output": 10, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                        { "model": "mock-model", "usage": { "inputOther": 93, "output": 10, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated                { "model": "mock-model", "contextTokens": 103, "maxContextTokens": 1000000, "contextUsage": 0.000103, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 98, "output": 32, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 98, "output": 32, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 98, "output": 32, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
diff --git a/packages/agent-core/test/agent/plan.test.ts b/packages/agent-core/test/agent/plan.test.ts
index 9996e7829..ca40554b5 100644
--- a/packages/agent-core/test/agent/plan.test.ts
+++ b/packages/agent-core/test/agent/plan.test.ts
@@ -451,7 +451,7 @@ describe('plan allows safe tool flow', () => {
       [emit] tool.progress               { "turnId": 0, "toolCallId": "call_bash", "update": { "kind": "stdout", "text": "plan-safe" } }
       [wire] context.append_loop_event   { "event": { "type": "tool.result", "parentUuid": "call_bash", "toolCallId": "call_bash", "result": { "output": "plan-safe" } }, "time": "<time>" }
       [emit] tool.result                 { "turnId": 0, "toolCallId": "call_bash", "output": "plan-safe" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 565, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 565, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use", "messageId": "mock-1" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 565, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 565, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 588, "maxContextTokens": 1000000, "contextUsage": 0.000588, "planMode": true, "swarmMode": false, "permission": "yolo", "usage": { "byModel": { "mock-model": { "inputOther": 565, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 565, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 565, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -459,7 +459,7 @@ describe('plan allows safe tool flow', () => {
       [emit] turn.step.started           { "turnId": 0, "step": 2, "stepId": "<uuid-3>" }
       [emit] assistant.delta             { "turnId": 0, "delta": "The safe command printed plan-safe." }
       [wire] context.append_loop_event   { "event": { "type": "content.part", "uuid": "<uuid-4>", "turnId": "0", "step": 2, "stepUuid": "<uuid-3>", "part": { "type": "text", "text": "The safe command printed plan-safe." } }, "time": "<time>" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 592, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 592, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-2" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 2, "stepId": "<uuid-3>", "usage": { "inputOther": 592, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 592, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 604, "maxContextTokens": 1000000, "contextUsage": 0.000604, "planMode": true, "swarmMode": false, "permission": "yolo", "usage": { "byModel": { "mock-model": { "inputOther": 1157, "output": 35, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 1157, "output": 35, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 1157, "output": 35, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -505,7 +505,7 @@ describe('plan mode Bash ordinary permission behavior', () => {
       [emit] tool.progress               { "turnId": 0, "toolCallId": "call_bash", "update": { "kind": "stdout", "text": "removed" } }
       [wire] context.append_loop_event   { "event": { "type": "tool.result", "parentUuid": "call_bash", "toolCallId": "call_bash", "result": { "output": "removed" } }, "time": "<time>" }
       [emit] tool.result                 { "turnId": 0, "toolCallId": "call_bash", "output": "removed" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 562, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 562, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use", "messageId": "mock-1" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 562, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 562, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 585, "maxContextTokens": 1000000, "contextUsage": 0.000585, "planMode": true, "swarmMode": false, "permission": "yolo", "usage": { "byModel": { "mock-model": { "inputOther": 562, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 562, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 562, "output": 23, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -513,7 +513,7 @@ describe('plan mode Bash ordinary permission behavior', () => {
       [emit] turn.step.started           { "turnId": 0, "step": 2, "stepId": "<uuid-3>" }
       [emit] assistant.delta             { "turnId": 0, "delta": "The command completed." }
       [wire] context.append_loop_event   { "event": { "type": "content.part", "uuid": "<uuid-4>", "turnId": "0", "step": 2, "stepUuid": "<uuid-3>", "part": { "type": "text", "text": "The command completed." } }, "time": "<time>" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 588, "output": 9, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 588, "output": 9, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-2" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 2, "stepId": "<uuid-3>", "usage": { "inputOther": 588, "output": 9, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 588, "output": 9, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 597, "maxContextTokens": 1000000, "contextUsage": 0.000597, "planMode": true, "swarmMode": false, "permission": "yolo", "usage": { "byModel": { "mock-model": { "inputOther": 1150, "output": 32, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 1150, "output": 32, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 1150, "output": 32, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
diff --git a/packages/agent-core/test/agent/tool.test.ts b/packages/agent-core/test/agent/tool.test.ts
index c30398a47..c3f1ccb3d 100644
--- a/packages/agent-core/test/agent/tool.test.ts
+++ b/packages/agent-core/test/agent/tool.test.ts
@@ -328,7 +328,7 @@ describe('Agent tools', () => {
     expect(await ctx.untilTurnEnd()).toMatchInlineSnapshot(`
       [wire] context.append_loop_event   { "event": { "type": "tool.result", "parentUuid": "call_lookup", "toolCallId": "call_lookup", "result": { "output": "moon-result" } }, "time": "<time>" }
       [emit] tool.result                 { "turnId": 0, "toolCallId": "call_lookup", "output": "moon-result" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 88, "output": 16, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 88, "output": 16, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use", "messageId": "mock-1" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 88, "output": 16, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 88, "output": 16, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 104, "maxContextTokens": 1000000, "contextUsage": 0.000104, "planMode": false, "swarmMode": false, "permission": "auto", "usage": { "byModel": { "mock-model": { "inputOther": 88, "output": 16, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 88, "output": 16, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 88, "output": 16, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -336,7 +336,7 @@ describe('Agent tools', () => {
       [emit] turn.step.started           { "turnId": 0, "step": 2, "stepId": "<uuid-3>" }
       [emit] assistant.delta             { "turnId": 0, "delta": "The lookup result is moon-result." }
       [wire] context.append_loop_event   { "event": { "type": "content.part", "uuid": "<uuid-4>", "turnId": "0", "step": 2, "stepUuid": "<uuid-3>", "part": { "type": "text", "text": "The lookup result is moon-result." } }, "time": "<time>" }
-      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 108, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event   { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 108, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-2" }, "time": "<time>" }
       [emit] turn.step.completed         { "turnId": 0, "step": 2, "stepId": "<uuid-3>", "usage": { "inputOther": 108, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                { "model": "mock-model", "usage": { "inputOther": 108, "output": 12, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated        { "model": "mock-model", "contextTokens": 120, "maxContextTokens": 1000000, "contextUsage": 0.00012, "planMode": false, "swarmMode": false, "permission": "auto", "usage": { "byModel": { "mock-model": { "inputOther": 196, "output": 28, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 196, "output": 28, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 196, "output": 28, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -362,7 +362,7 @@ describe('Agent tools', () => {
       [emit] turn.step.started            { "turnId": 1, "step": 1, "stepId": "<uuid-5>" }
       [emit] assistant.delta              { "turnId": 1, "delta": "No lookup tool is available." }
       [wire] context.append_loop_event    { "event": { "type": "content.part", "uuid": "<uuid-6>", "turnId": "1", "step": 1, "stepUuid": "<uuid-5>", "part": { "type": "text", "text": "No lookup tool is available." } }, "time": "<time>" }
-      [wire] context.append_loop_event    { "event": { "type": "step.end", "uuid": "<uuid-5>", "turnId": "1", "step": 1, "usage": { "inputOther": 128, "output": 10, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event    { "event": { "type": "step.end", "uuid": "<uuid-5>", "turnId": "1", "step": 1, "usage": { "inputOther": 128, "output": 10, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-3" }, "time": "<time>" }
       [emit] turn.step.completed          { "turnId": 1, "step": 1, "stepId": "<uuid-5>", "usage": { "inputOther": 128, "output": 10, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                 { "model": "mock-model", "usage": { "inputOther": 128, "output": 10, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated         { "model": "mock-model", "contextTokens": 138, "maxContextTokens": 1000000, "contextUsage": 0.000138, "planMode": false, "swarmMode": false, "permission": "auto", "usage": { "byModel": { "mock-model": { "inputOther": 324, "output": 38, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 324, "output": 38, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 128, "output": 10, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
diff --git a/packages/agent-core/test/agent/turn.test.ts b/packages/agent-core/test/agent/turn.test.ts
index d1e450375..417b2c5f7 100644
--- a/packages/agent-core/test/agent/turn.test.ts
+++ b/packages/agent-core/test/agent/turn.test.ts
@@ -1685,7 +1685,7 @@ describe('Agent turn flow', () => {
       [emit] tool.progress                       { "turnId": 0, "toolCallId": "call_bash", "update": { "kind": "stdout", "text": "approved" } }
       [wire] context.append_loop_event           { "event": { "type": "tool.result", "parentUuid": "call_bash", "toolCallId": "call_bash", "result": { "output": "approved" } }, "time": "<time>" }
       [emit] tool.result                         { "turnId": 0, "toolCallId": "call_bash", "output": "approved" }
-      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 7, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }, "time": "<time>" }
+      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-1>", "turnId": "0", "step": 1, "usage": { "inputOther": 7, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use", "messageId": "mock-1" }, "time": "<time>" }
       [emit] turn.step.completed                 { "turnId": 0, "step": 1, "stepId": "<uuid-1>", "usage": { "inputOther": 7, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "tool_use" }
       [wire] usage.record                        { "model": "mock-model", "usage": { "inputOther": 7, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated                { "model": "mock-model", "contextTokens": 29, "maxContextTokens": 1000000, "contextUsage": 0.000029, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 7, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 7, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 7, "output": 22, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
@@ -1694,7 +1694,7 @@ describe('Agent turn flow', () => {
       [emit] turn.step.started                   { "turnId": 0, "step": 2, "stepId": "<uuid-3>" }
       [emit] assistant.delta                     { "turnId": 0, "delta": "Approved, and I saw the steer." }
       [wire] context.append_loop_event           { "event": { "type": "content.part", "uuid": "<uuid-4>", "turnId": "0", "step": 2, "stepUuid": "<uuid-3>", "part": { "type": "text", "text": "Approved, and I saw the steer." } }, "time": "<time>" }
-      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 39, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }, "time": "<time>" }
+      [wire] context.append_loop_event           { "event": { "type": "step.end", "uuid": "<uuid-3>", "turnId": "0", "step": 2, "usage": { "inputOther": 39, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn", "messageId": "mock-2" }, "time": "<time>" }
       [emit] turn.step.completed                 { "turnId": 0, "step": 2, "stepId": "<uuid-3>", "usage": { "inputOther": 39, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "finishReason": "end_turn" }
       [wire] usage.record                        { "model": "mock-model", "usage": { "inputOther": 39, "output": 11, "inputCacheRead": 0, "inputCacheCreation": 0 }, "usageScope": "turn", "time": "<time>" }
       [emit] agent.status.updated                { "model": "mock-model", "contextTokens": 50, "maxContextTokens": 1000000, "contextUsage": 0.00005, "planMode": false, "swarmMode": false, "permission": "manual", "usage": { "byModel": { "mock-model": { "inputOther": 46, "output": 33, "inputCacheRead": 0, "inputCacheCreation": 0 } }, "total": { "inputOther": 46, "output": 33, "inputCacheRead": 0, "inputCacheCreation": 0 }, "currentTurn": { "inputOther": 46, "output": 33, "inputCacheRead": 0, "inputCacheCreation": 0 } } }
diff --git a/packages/agent-core/test/loop/events.e2e.test.ts b/packages/agent-core/test/loop/events.e2e.test.ts
index 47f951e5d..48d82bb95 100644
--- a/packages/agent-core/test/loop/events.e2e.test.ts
+++ b/packages/agent-core/test/loop/events.e2e.test.ts
@@ -158,6 +158,19 @@ describe('runTurn — LoopEventDispatcher live event containment', () => {
     expect(typeof tr?.result.output).toBe('string');
   });
 
+  it('records the provider response id on step.end', async () => {
+    const { context } = await runTurn({
+      responses: [
+        {
+          ...makeEndTurnResponse('ok'),
+          messageId: 'chatcmpl-test',
+        },
+      ],
+    });
+
+    expect(context.stepEnds()[0]?.messageId).toBe('chatcmpl-test');
+  });
+
   it('accepts a custom emitter function', async () => {
     class StrictCollector {
       readonly events: LoopEvent[] = [];