test(perf): add performance instrumentation tests

tests/unit/chatcore-streaming-pipeline.test.ts

@@ -7,9 +7,8 @@
 import { test } from "node:test";
 import assert from "node:assert/strict";
 
-const { assembleStreamingPipeline } = await import(
-  "../../open-sse/handlers/chatCore/streamingPipeline.ts"
-);
+const { assembleStreamingPipeline } =
+  await import("../../open-sse/handlers/chatCore/streamingPipeline.ts");
 
 // A fake stream: each pipeThrough appends the transform's tag and returns a new fake stream.
 function fakeStream(tag: string, log: string[]) {
@@ -100,3 +99,37 @@ test("full chain order: pii → progress → heartbeat → echo", () => {
   assembleStreamingPipeline(baseArgs({ echoModel: "alias-x" }), deps);
   assert.deepEqual(log, ["pii-flag", "progress", "heartbeat", "echo"]);
 });
+
+test("pipeline assembly creates performance mark and measure entries", () => {
+  performance.clearMarks();
+  performance.clearMeasures();
+  const { deps } = makeDeps();
+  assembleStreamingPipeline(baseArgs(), deps);
+  assert.equal(performance.getEntriesByName("omni-pipeline-start").length, 1, "start mark");
+  assert.equal(performance.getEntriesByName("omni-pipeline-end").length, 1, "end mark");
+  assert.equal(performance.getEntriesByName("omni-pipeline").length, 1, "measure");
+});
+
+test("re-entering pipeline clears previous timeline entries", () => {
+  performance.clearMarks();
+  performance.clearMeasures();
+  const { deps } = makeDeps();
+  // First call creates entries
+  assembleStreamingPipeline(baseArgs(), deps);
+  // Second call — clearMarks/clearMeasures runs before new marks, so count stays 1
+  assembleStreamingPipeline(baseArgs(), deps);
+  assert.equal(performance.getEntriesByName("omni-pipeline-start").length, 1, "start cleared");
+  assert.equal(performance.getEntriesByName("omni-pipeline-end").length, 1, "end cleared");
+  assert.equal(performance.getEntriesByName("omni-pipeline").length, 1, "measure cleared");
+});
+
+test("performance measure has positive duration", () => {
+  performance.clearMarks();
+  performance.clearMeasures();
+  const { deps } = makeDeps();
+  assembleStreamingPipeline(baseArgs(), deps);
+  const [entry] = performance.getEntriesByName("omni-pipeline");
+  assert.ok(entry, "measure exists");
+  assert.equal(entry.entryType, "measure");
+  assert.ok(entry.duration >= 0, `duration ${entry.duration} >= 0`);
+});