feat: add Workbench L0 phase timing

internal/workbench/workbench.test.ts

@@ -165,10 +165,10 @@ describe("Workbench native HTTP adapter", () => {
       ], {});
       for (let index = 0; index < 20 && subscribers.size === 0; index += 1) await Bun.sleep(5);
       const events = [
-        { type: "user", eventType: "user" },
-        { type: "backend", eventType: "backend" },
-        { type: "assistant", eventType: "assistant", final: true, replyAuthority: true, finalResponse: { text: "done" } },
-        { type: "result", eventType: "terminal", terminal: true, terminalStatus: "completed", status: "completed" }
+        { type: "user", eventType: "user", createdAt: "2026-07-19T16:00:00.000Z" },
+        { type: "backend", eventType: "backend", createdAt: "2026-07-19T16:00:02.000Z" },
+        { type: "assistant", eventType: "assistant", createdAt: "2026-07-19T16:01:02.000Z", final: true, replyAuthority: true, finalResponse: { text: "done" } },
+        { type: "result", eventType: "terminal", createdAt: "2026-07-19T16:01:03.000Z", terminal: true, terminalStatus: "completed", status: "completed" }
       ];
       for (const event of events) {
         for (const listener of subscribers) listener({ schema: "hwlab.event.v1", sessionId: "ses_l0_semantics", traceId: "trc_l0_semantics", event });
@@ -181,7 +181,27 @@ describe("Workbench native HTTP adapter", () => {
         observedSemantics: ["user", "backend", "assistant", "terminal", "final"],
         missingSemantics: [],
         semanticCounts: { user: 1, backend: 1, assistant: 1, terminal: 1, final: 1 },
-        terminalStatuses: ["completed"]
+        terminalStatuses: ["completed"],
+        timing: {
+          clock: "agentrun-source-event-created-at",
+          phasesMs: {
+            firstEventToBackend: 2000,
+            admissionAndDispatch: null,
+            runnerProvisioning: null,
+            runtimePreparation: null,
+            providerExecution: null,
+            backendToAssistant: 60000,
+            assistantToTerminal: 1000,
+            firstEventToTerminal: 63000,
+            firstEventToFinal: 62000
+          },
+          slowestGap: {
+            durationMs: 60000,
+            toIndex: 2,
+            toEventType: "assistant"
+          },
+          valuesPrinted: false
+        }
       });
     } finally {
       server.stop(true);