feat(agent-core-v2): attribute event-loop-busy decode time to the client

Author: elkaix

apps/pythinker-code/src/utils/usage/debug-timing.ts

@@ -24,6 +24,7 @@ export interface StepTimingInput {
    */
   readonly llmServerDecodeMs?: number;
   readonly llmClientConsumeMs?: number;
+  readonly llmClientBlockedMs?: number;
   readonly usage?: DebugTokenUsage;
 }
 
@@ -119,7 +120,9 @@ function formatDecodeSplit(input: StepTimingInput): string {
   const server = input.llmServerDecodeMs;
   const client = input.llmClientConsumeMs;
   if (server === undefined || client === undefined) return '';
-  return `; server ${formatDuration(server)} + client ${formatDuration(client)}`;
+  const blocked = input.llmClientBlockedMs;
+  const blockedPart = blocked === undefined ? '' : ` (busy ${formatDuration(blocked)})`;
+  return `; server ${formatDuration(server)}${blockedPart} + client ${formatDuration(client)}`;
 }
 
 function formatDuration(ms: number): string {

apps/pythinker-code/test/utils/usage/debug-timing.test.ts

@@ -27,6 +27,20 @@ describe('formatStepDebugTiming', () => {
     expect(result).toBe('[Debug] TTFT: 800ms | TPS: 40.0 tok/s (200 tokens in 5.0s)');
   });
 
+  it('appends the blocked share to the decode split when present', () => {
+    const result = formatStepDebugTiming({
+      llmFirstTokenLatencyMs: 800,
+      llmStreamDurationMs: 6000,
+      llmServerDecodeMs: 6000,
+      llmClientConsumeMs: 25,
+      llmClientBlockedMs: 4875,
+      usage: { output: 216 },
+    });
+    expect(result).toBe(
+      '[Debug] TTFT: 800ms | TPS: 36.0 tok/s (216 tokens in 6.0s; server 6.0s (busy 4.9s) + client 25ms)',
+    );
+  });
+
   it('formats input tokens and cache read/write counts', () => {
     const result = formatStepDebugTiming({
       llmFirstTokenLatencyMs: 800,

apps/vis/web/src/components/analysis/TimelineTab.tsx

@@ -307,9 +307,10 @@ function StepRow({ step, turnDurationMs }: { step: StepNode; turnDurationMs?: nu
         {step.llmServerDecodeMs !== undefined && step.llmClientConsumeMs !== undefined ? (
           <span
             className="text-fg-3 tabular"
-            title="decode window split (server awaiting parts + client processing parts)"
+            title="decode window split (server awaiting parts + client processing parts; busy = event loop busy with other work)"
           >
             decode {step.llmServerDecodeMs}+{step.llmClientConsumeMs}ms
+            {step.llmClientBlockedMs !== undefined ? ` (busy ${step.llmClientBlockedMs}ms)` : ''}
           </span>
         ) : null}
         {step.contextTokens !== undefined ? (

apps/vis/web/src/components/wire/parts.tsx

@@ -397,6 +397,11 @@ export function LoopEventDetail({ event }: { event: LoopRecordedEvent }) {
                 <span className="text-fg-1">{event.llmClientConsumeMs} ms</span>
               </FieldRow>
             ) : null}
+            {event.llmClientBlockedMs !== undefined ? (
+              <FieldRow label="streamDuration/blocked">
+                <span className="text-fg-1">{event.llmClientBlockedMs} ms</span>
+              </FieldRow>
+            ) : null}
           </div>
           {usage !== undefined ? (
             <div>

apps/vis/web/src/lib/analysis.ts

@@ -60,6 +60,7 @@ export interface StepNode {
   /** Decode split: server time awaiting parts vs. client time processing them. */
   llmServerDecodeMs?: number;
   llmClientConsumeMs?: number;
+  llmClientBlockedMs?: number;
   content: ContentSummary;
   toolCalls: ToolCallNode[];
 }
@@ -375,6 +376,7 @@ export function analyzeWire(entries: readonly WireEntry[]): Analysis {
             step.llmServerFirstTokenMs = ev.llmServerFirstTokenMs;
             step.llmServerDecodeMs = ev.llmServerDecodeMs;
             step.llmClientConsumeMs = ev.llmClientConsumeMs;
+            step.llmClientBlockedMs = ev.llmClientBlockedMs;
             if (step.beginTime !== undefined && t !== undefined) step.durationMs = t - step.beginTime;
             // Steps don't carry a generic 'error' finish reason (errors are
             // thrown, not recorded). 'filtered' means the provider blocked the

packages/agent-core-v2/src/agent/contextMemory/loopEventFold.ts

@@ -30,6 +30,7 @@ export type LoopRecordedEvent =
       readonly llmServerFirstTokenMs?: number;
       readonly llmServerDecodeMs?: number;
       readonly llmClientConsumeMs?: number;
+      readonly llmClientBlockedMs?: number;
       readonly messageId?: string;
       readonly providerFinishReason?: FinishReason;
       readonly rawFinishReason?: string;

packages/agent-core-v2/src/agent/llmRequester/llmRequesterService.ts

@@ -815,6 +815,7 @@ export class AgentLLMRequesterService implements IAgentLLMRequesterService {
     }
     if (timing.serverDecodeMs !== undefined) payload['serverDecodeMs'] = timing.serverDecodeMs;
     if (timing.clientConsumeMs !== undefined) payload['clientConsumeMs'] = timing.clientConsumeMs;
+    if (timing.clientBlockedMs !== undefined) payload['clientBlockedMs'] = timing.clientBlockedMs;
     this.log.info('llm response', payload);
   }
 

packages/agent-core-v2/src/agent/loop/loopService.ts

@@ -1041,6 +1041,7 @@ export class AgentLoopService extends Disposable implements IAgentLoopService {
       llmServerFirstTokenMs: timing?.serverFirstTokenMs,
       llmServerDecodeMs: timing?.serverDecodeMs,
       llmClientConsumeMs: timing?.clientConsumeMs,
+      llmClientBlockedMs: timing?.clientBlockedMs,
       messageId: response.providerMessageId,
       providerFinishReason: response.providerFinishReason,
       rawFinishReason: response.rawFinishReason,
@@ -1102,6 +1103,7 @@ export class AgentLoopService extends Disposable implements IAgentLoopService {
         llmServerFirstTokenMs: response.timing?.serverFirstTokenMs,
         llmServerDecodeMs: response.timing?.serverDecodeMs,
         llmClientConsumeMs: response.timing?.clientConsumeMs,
+        llmClientBlockedMs: response.timing?.clientBlockedMs,
         providerFinishReason: response.providerFinishReason,
         rawFinishReason: response.rawFinishReason,
       }),

packages/agent-core-v2/src/agent/loop/turnEvents.ts

@@ -123,6 +123,7 @@ export interface TurnStepCompletedPayload {
   readonly llmServerFirstTokenMs?: number;
   readonly llmServerDecodeMs?: number;
   readonly llmClientConsumeMs?: number;
+  readonly llmClientBlockedMs?: number;
   readonly providerFinishReason?: FinishReason;
   readonly rawFinishReason?: string;
 }

packages/agent-core-v2/src/kosong/contract/provider.ts

@@ -62,6 +62,7 @@ export interface ToolCallIdPolicy {
 export interface StreamDecodeStats {
   readonly serverDecodeMs: number;
   readonly clientConsumeMs: number;
+  readonly clientBlockedMs?: number;
 }
 
 export interface VideoUploadInput {