fix(llm): request_id 条件透传贯通网关日志（CR-H4，守 §9.3）

packages/llm_gateway/tests/test_gateway.py

@@ -5,6 +5,7 @@ from __future__ import annotations
 import uuid
 
 import pytest
+import structlog
 from fakes import FakeAdapter, FakeLedger, fake_route
 from ww_llm_gateway.gateway import Gateway
 from ww_llm_gateway.routing import resolve_route
@@ -60,6 +61,33 @@ async def test_stream_yields_deltas_and_records_once(req: LlmRequest) -> None:
     assert ledger.records[0].output_tokens == 50
 
 
+async def test_run_logs_request_id_from_request(scope: Scope) -> None:
+    # CR-H4：调用方设了 request_id 时，网关 llm_call 日志必须带上它（贯通 §9.3 追踪）。
+    ledger = FakeLedger()
+    gw = Gateway({"deepseek": FakeAdapter()}, ledger, resolver=fake_route)
+    req = LlmRequest(tier="writer", input="x", scope=scope, request_id="rid-xyz")
+
+    with structlog.testing.capture_logs() as logs:
+        await gw.run(req)
+
+    call = next(entry for entry in logs if entry["event"] == "llm_call")
+    assert call["request_id"] == "rid-xyz"
+
+
+async def test_run_omits_request_id_when_unset(scope: Scope) -> None:
+    # 未设 request_id 时**不得**发出该键——否则 None 会覆盖 merge_contextvars 供的 id，
+    # 反倒回退了 sync/SSE 路径的追踪（条件透传锁定）。
+    ledger = FakeLedger()
+    gw = Gateway({"deepseek": FakeAdapter()}, ledger, resolver=fake_route)
+    req = LlmRequest(tier="writer", input="x", scope=scope)
+
+    with structlog.testing.capture_logs() as logs:
+        await gw.run(req)
+
+    call = next(entry for entry in logs if entry["event"] == "llm_call")
+    assert "request_id" not in call
+
+
 async def test_unknown_provider_raises_llm_unavailable(req: LlmRequest) -> None:
     gw = Gateway({}, FakeLedger(), resolver=fake_route)
 

packages/llm_gateway/tests/test_types.py

@@ -17,6 +17,7 @@ def test_llm_request_has_no_thinking_field() -> None:
         "output_schema",
         "max_tokens",
         "scope",
+        "request_id",  # CR-H4：可选端到端追踪字段（additive/optional）。
     }
     # 同名但另一处 live 字段 `Capabilities.thinking`（适配器能力矩阵）不受影响。
     assert "thinking" in Capabilities.model_fields