fix: 压制 agentMessage lifecycle 噪声 (#72)

Co-authored-by: Codex <codex@pikas.tech>

src/selftest/cases/30-codex-stdio.ts

@@ -92,6 +92,7 @@ const selfTest: SelfTestCase = async (context) => {
     const turnCompletedIndex = finalMessageItems.findIndex((event) => event.type === "backend_status" && eventPayload(event).phase === "turn/completed");
     assert.ok(progressMessageIndex >= 0 && progressMessageIndex < turnCompletedIndex, "progress agentMessage should be emitted before turn/completed instead of being delayed to final response");
     assert.ok(finalMessageIndex >= 0 && finalMessageIndex < turnCompletedIndex, "final agentMessage should be emitted before turn/completed instead of being delayed to final response");
+    assert.equal(finalMessageItems.some((event) => event.type === "backend_status" && String(eventPayload(event).phase ?? "").startsWith("item/agentMessage:")), false, "agentMessage lifecycle must not be persisted as backend_status noise");
 
     const staleThread = await createStaleThreadRun(client, context);
     const staleThreadResult = await runOnce({
@@ -144,6 +145,7 @@ const selfTest: SelfTestCase = async (context) => {
     assert.equal(noisyItems.some((event) => event.type === "tool_call" && eventPayload(event).type === "reasoning"), false, "reasoning items must not be persisted as tool_call");
     assert.ok(noisyItems.some((event) => event.type === "tool_call" && eventPayload(event).method === "item/started" && eventPayload(event).type === "commandExecution"), "real commandExecution tool call should remain visible");
     assert.equal(noisyItems.some((event) => event.type === "tool_call" && eventPayload(event).type !== "commandExecution"), false, "non-commandExecution item lifecycle must not be persisted as tool_call");
+    assert.equal(noisyItems.some((event) => event.type === "backend_status" && String(eventPayload(event).phase ?? "").startsWith("item/agentMessage:")), false, "agentMessage lifecycle must not be persisted as backend_status noise");
     assert.equal(noisyPhases.includes("backend-turn-running"), false, "backend progress ticks must be summarized instead of persisted as durable trace events");
     const noisyFinished = noisyItems.find((event) => event.type === "backend_status" && eventPayload(event).phase === "backend-turn-finished");
     assert.equal(eventPayload(noisyFinished ?? { payload: {} }).progressEventsPrinted, false, "backend-turn-finished must declare progress ticks were not printed as events");