feat(eval): server-side replay/phase1 timing + memoir phase1 batch chunking

- Replay and memoir-submit responses include started/finished UTC and elapsed_ms;
  Phase1 poll exposes Redis-backed submit time and elapsed_ms_since_submit.
- Phase1 batch LLM splits segments by memoir_phase1_batch_llm_chunk_size with
  bisect fallback per chunk; Playground shows server timings.

Made-with: Cursor

api/tests/evaluation/test_memoir_readiness_router.py

@@ -1,5 +1,7 @@
 """memoir-phase1-ready internal 路由（依赖注入替身）。"""
 
+from datetime import datetime, timezone
+
 import pytest
 from httpx import ASGITransport, AsyncClient
 
@@ -54,6 +56,60 @@ async def test_memoir_phase1_ready_returns_bundle(monkeypatch: pytest.MonkeyPatc
     assert body["pending_segment_ids"] == []
 
 
+@pytest.mark.asyncio
+async def test_memoir_phase1_ready_includes_server_elapsed_fields(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    from fastapi import FastAPI
+
+    monkeypatch.setattr(
+        "app.core.config.settings.internal_eval_api_key",
+        "secret",
+        raising=False,
+    )
+    from app.features.evaluation.deps import get_memoir_readiness_service
+    from app.features.evaluation.router import router
+
+    class _Fake:
+        async def memoir_phase1_ready_for_segments(
+            self, *, conversation_id: str, segment_ids: list[str]
+        ) -> MemoirPhase1ReadyOut:
+            return MemoirPhase1ReadyOut(
+                ready=False,
+                checked_segment_ids=list(segment_ids),
+                pending_segment_ids=["pending-1"],
+                job_submitted_at_utc=datetime(
+                    2026, 4, 9, 8, 0, 0, tzinfo=timezone.utc
+                ),
+                elapsed_ms_since_submit=12_000,
+                durations_ms={"since_playground_submit": 12_000},
+            )
+
+    app = FastAPI()
+    app.include_router(router, prefix="/internal/api/evaluation")
+
+    async def _override_auth():
+        from app.features.evaluation.internal_auth import InternalEvalPrincipal
+
+        return InternalEvalPrincipal()
+
+    app.dependency_overrides[get_internal_eval_principal] = _override_auth
+    app.dependency_overrides[get_memoir_readiness_service] = lambda: _Fake()
+
+    transport = ASGITransport(app=app)
+    async with AsyncClient(transport=transport, base_url="http://t") as client:
+        r = await client.get(
+            "/internal/api/evaluation/sessions/cid-a/memoir-phase1-ready",
+            headers={"X-Internal-Eval-Key": "secret"},
+            params=[("segment_ids", "s1")],
+        )
+    assert r.status_code == 200
+    body = r.json()
+    assert body["elapsed_ms_since_submit"] == 12_000
+    assert body["durations_ms"]["since_playground_submit"] == 12_000
+    assert body["job_submitted_at_utc"] is not None
+
+
 @pytest.mark.asyncio
 async def test_memoir_phase1_ready_404_propagates(monkeypatch: pytest.MonkeyPatch) -> None:
     from fastapi import FastAPI

api/tests/evaluation/test_replay_timing_response.py

@@ -0,0 +1,71 @@
+"""replay/conversation 响应携带服务端 elapsed 字段。"""
+
+from __future__ import annotations
+
+from datetime import datetime, timezone
+
+import pytest
+from httpx import ASGITransport, AsyncClient
+
+from app.features.evaluation.internal_auth import get_internal_eval_principal
+from app.features.evaluation.replay_service import ReplayServerTiming
+
+
+@pytest.mark.asyncio
+async def test_replay_conversation_includes_server_elapsed_ms(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    from fastapi import FastAPI
+
+    monkeypatch.setattr(
+        "app.core.config.settings.internal_eval_api_key",
+        "secret",
+        raising=False,
+    )
+    from app.features.evaluation.deps import get_replay_conversation_service
+    from app.features.evaluation.router import router
+
+    t0 = datetime(2026, 4, 9, 10, 0, 0, tzinfo=timezone.utc)
+    t1 = datetime(2026, 4, 9, 10, 0, 1, tzinfo=timezone.utc)
+
+    class _FakeReplay:
+        async def replay_utterances(self, **kwargs):
+            return (
+                1,
+                ["seg-a"],
+                ReplayServerTiming(
+                    started_at_utc=t0,
+                    finished_at_utc=t1,
+                    elapsed_ms=150,
+                ),
+            )
+
+    app = FastAPI()
+    app.include_router(router, prefix="/internal/api/evaluation")
+
+    async def _override_auth():
+        from app.features.evaluation.internal_auth import InternalEvalPrincipal
+
+        return InternalEvalPrincipal()
+
+    app.dependency_overrides[get_internal_eval_principal] = _override_auth
+    app.dependency_overrides[get_replay_conversation_service] = lambda: _FakeReplay()
+
+    transport = ASGITransport(app=app)
+    async with AsyncClient(transport=transport, base_url="http://t") as client:
+        r = await client.post(
+            "/internal/api/evaluation/replay/conversation",
+            headers={"X-Internal-Eval-Key": "secret"},
+            json={
+                "conversation_id": "00000000-0000-0000-0000-000000000099",
+                "user_utterances": ["hi"],
+                "flush_memoir_after": False,
+                "skip_memoir": True,
+                "skip_tts": True,
+            },
+        )
+    assert r.status_code == 200
+    body = r.json()
+    assert body["elapsed_ms"] == 150
+    assert body["started_at_utc"] is not None
+    assert body["finished_at_utc"] is not None