diff --git a/src/polygateway/middleware/retry.py b/src/polygateway/middleware/retry.py
index acb7da7..60c746b 100644
--- a/src/polygateway/middleware/retry.py
+++ b/src/polygateway/middleware/retry.py
@@ -438,6 +438,7 @@ class RetryMW:
             usage_source=result.usage_source,
             cached_prompt_tokens=result.cached_prompt_tokens,
             model_reported=result.model_reported,
+            reasoning_tokens=result.reasoning_tokens,
         )
 
     async def _settle_and_release(self, permit: Permit, actual: int) -> None:
diff --git a/src/polygateway/middleware/telemetry.py b/src/polygateway/middleware/telemetry.py
index b2093c7..66b7cfb 100644
--- a/src/polygateway/middleware/telemetry.py
+++ b/src/polygateway/middleware/telemetry.py
@@ -64,6 +64,7 @@ class TelemetryEmitter:
             error=error,
             cached_prompt_tokens=response.cached_prompt_tokens if response else None,
             model_reported=response.model_reported if response else None,
+            reasoning_tokens=response.reasoning_tokens if response else None,
             # 唯一有"生效源"的入口,故是唯一能并上 extra_body 的(设计决策 D)
             sampling=canonical_sampling_json(merge_sampling(source.extra_body, request.sampling)),
         )
@@ -90,6 +91,7 @@ class TelemetryEmitter:
             # 统计供应商缓存命中率必须带 WHERE cache_hit = false,否则重复计数。
             cached_prompt_tokens=response.cached_prompt_tokens,
             model_reported=response.model_reported,
+            reasoning_tokens=response.reasoning_tokens,
             # 由最外层 TelemetryMW 调用,手上没有 source。缓存命中行无损:
             # sampling 已进缓存 key,能命中即意味调用级参数与历史那次逐字相同
             sampling=canonical_sampling_json(request.sampling),
@@ -117,6 +119,7 @@ class TelemetryEmitter:
             error=error,
             cached_prompt_tokens=None,
             model_reported=None,
+            reasoning_tokens=None,
             # 无具体源,与 model/provider/source_name 置空同一先例(设计决策 D)
             sampling=canonical_sampling_json(request.sampling),
         )
@@ -142,6 +145,7 @@ class TelemetryEmitter:
         cached_prompt_tokens: int | None,
         model_reported: str | None,
         sampling: str | None,
+        reasoning_tokens: int | None,
     ) -> None:
         try:
             # 成本换算(M2 §6): 成功行按单价换算;缓存命中 0.0(未产生新调用);
@@ -182,6 +186,7 @@ class TelemetryEmitter:
                 cached_prompt_tokens=cached_prompt_tokens,
                 model_reported=model_reported,
                 sampling=sampling,
+                reasoning_tokens=reasoning_tokens,
             )
         except asyncio.CancelledError:
             raise
diff --git a/src/polygateway/ports.py b/src/polygateway/ports.py
index 5425dfe..1765d85 100644
--- a/src/polygateway/ports.py
+++ b/src/polygateway/ports.py
@@ -275,4 +275,5 @@ class TelemetryRecorder(Protocol):
         cached_prompt_tokens: int | None,
         model_reported: str | None,
         sampling: str | None,
+        reasoning_tokens: int | None,
     ) -> None: ...
diff --git a/src/polygateway/telemetry/postgres.py b/src/polygateway/telemetry/postgres.py
index f3fac3c..a195aa5 100644
--- a/src/polygateway/telemetry/postgres.py
+++ b/src/polygateway/telemetry/postgres.py
@@ -42,7 +42,8 @@ CREATE TABLE IF NOT EXISTS llm_calls (
     created_at         TIMESTAMPTZ NOT NULL DEFAULT now(),
     cached_prompt_tokens INTEGER,
     model_reported       TEXT,
-    sampling             TEXT
+    sampling             TEXT,
+    reasoning_tokens     INTEGER
 );
 """
 
@@ -51,6 +52,7 @@ _BACKFILL = (
     ("cached_prompt_tokens", "ALTER TABLE llm_calls ADD COLUMN cached_prompt_tokens INTEGER"),
     ("model_reported", "ALTER TABLE llm_calls ADD COLUMN model_reported TEXT"),
     ("sampling", "ALTER TABLE llm_calls ADD COLUMN sampling TEXT"),
+    ("reasoning_tokens", "ALTER TABLE llm_calls ADD COLUMN reasoning_tokens INTEGER"),
 )
 
 # 探测现有列;尊重 search_path(to_regclass 按当前 search_path 解析)
@@ -81,6 +83,7 @@ _COLUMNS = (
     "cached_prompt_tokens",
     "model_reported",
     "sampling",
+    "reasoning_tokens",
 )
 
 _INSERT = (
diff --git a/src/polygateway/telemetry/sqlite.py b/src/polygateway/telemetry/sqlite.py
index a53b7d9..b8622c6 100644
--- a/src/polygateway/telemetry/sqlite.py
+++ b/src/polygateway/telemetry/sqlite.py
@@ -37,7 +37,8 @@ CREATE TABLE IF NOT EXISTS llm_calls (
     created_at         TEXT    NOT NULL DEFAULT (datetime('now')),
     cached_prompt_tokens INTEGER,
     model_reported       TEXT,
-    sampling             TEXT
+    sampling             TEXT,
+    reasoning_tokens     INTEGER
 );
 """
 
@@ -47,6 +48,7 @@ _BACKFILL_COLUMNS = (
     ("cached_prompt_tokens", "INTEGER"),
     ("model_reported", "TEXT"),
     ("sampling", "TEXT"),
+    ("reasoning_tokens", "INTEGER"),
 )
 
 _COLUMNS = (
@@ -71,6 +73,7 @@ _COLUMNS = (
     "cached_prompt_tokens",
     "model_reported",
     "sampling",
+    "reasoning_tokens",
 )
 
 _INSERT = (
diff --git a/src/polygateway/transports/openai_compat.py b/src/polygateway/transports/openai_compat.py
index c8111df..054b494 100644
--- a/src/polygateway/transports/openai_compat.py
+++ b/src/polygateway/transports/openai_compat.py
@@ -177,6 +177,25 @@ def _coerce_cached_tokens(usage: Any) -> int | None:
     return cached
 
 
+def _coerce_reasoning_tokens(usage: Any) -> int | None:
+    """取 usage.completion_tokens_details.reasoning_tokens(issue #6);形态异常一律 None。
+
+    与 `_coerce_cached_tokens` 逐条同构(两者是 OpenAI 兼容 usage 里对称的一对):
+    `0` 如实保留、负数与非整数归 None、`bool` 显式排除。差别只在语义——本字段
+    的 None 是"**本次调用**未上报"而非"该源不上报": 中转在上游不返回 usage 时
+    会本地补算并整体替换 usage 对象,把 details 一并吃掉(findings §4c)。
+    """
+    if not isinstance(usage, dict):
+        return None
+    details = usage.get("completion_tokens_details")
+    if not isinstance(details, dict):
+        return None
+    reasoning = details.get("reasoning_tokens")
+    if isinstance(reasoning, bool) or not isinstance(reasoning, int) or reasoning < 0:
+        return None
+    return reasoning
+
+
 def _coerce_model_reported(value: Any) -> str | None:
     """取响应体的 model 字段(issue #3);非 str 或空白串一律 None,收口时去空白。
 
@@ -400,6 +419,7 @@ class OpenAICompatTransport:
             raw={"usage": sink.get("usage")},
             cached_prompt_tokens=_coerce_cached_tokens(sink.get("usage")),
             model_reported=_coerce_model_reported(sink.get("model")),
+            reasoning_tokens=_coerce_reasoning_tokens(sink.get("usage")),
         )
 
     def _check_done(
@@ -484,6 +504,7 @@ class OpenAICompatTransport:
             raw={"usage": body.get("usage")},
             cached_prompt_tokens=_coerce_cached_tokens(body.get("usage")),
             model_reported=_coerce_model_reported(body.get("model")),
+            reasoning_tokens=_coerce_reasoning_tokens(body.get("usage")),
         )
 
     async def aclose(self) -> None:
diff --git a/src/polygateway/types.py b/src/polygateway/types.py
index 723131f..7a21924 100644
--- a/src/polygateway/types.py
+++ b/src/polygateway/types.py
@@ -99,6 +99,15 @@ class LLMResponse:
     model_reported: str | None = None
     """API 响应体里的 model 字段;None = 未上报。与 `model`(配置别名)可能
     分叉——供应商把别名指向新权重时,实验复现必须认这个串。"""
+    reasoning_tokens: int | None = None
+    """推理消耗的输出 token 数(含在 `completion_tokens` 内,故不影响成本总额,
+    只补归因;issue #6)。
+
+    `None` = **本次调用**未上报,**不是**"该源不上报"——中转网关在上游不返回
+    usage 时会用本地 tokenizer 补算并整体替换 usage 对象,把
+    `completion_tokens_details` 一并吃掉(findings §4c 实测同一请求 10 轮呈
+    6:4 双峰)。实测三家供应商在未推理时都是整个 details 缺失、无人上报 `0`,
+    故下游判据须为 `in (None, 0)`,写 `== 0` 的条件永远不成立。"""
 
 
 @dataclass(frozen=True)
@@ -151,9 +160,10 @@ class TransportResult:
     ttft_ms: float | None
     max_inter_token_ms: float | None
     raw: dict[str, Any]
-    # —— 可观测字段(issue #3;带默认值,非 OpenAI 兼容的 transport 可不填)——
+    # —— 可观测字段(issue #3/#6;带默认值,非 OpenAI 兼容的 transport 可不填)——
     cached_prompt_tokens: int | None = None
     model_reported: str | None = None
+    reasoning_tokens: int | None = None
 
 
 @dataclass(frozen=True)
diff --git a/tests/integration/test_postgres_telemetry.py b/tests/integration/test_postgres_telemetry.py
index 3b1203c..11382ad 100644
--- a/tests/integration/test_postgres_telemetry.py
+++ b/tests/integration/test_postgres_telemetry.py
@@ -43,6 +43,7 @@ _EXPECTED_COLUMNS = [
     "cached_prompt_tokens",
     "model_reported",
     "sampling",
+    "reasoning_tokens",
 ]
 
 # run 级前缀: 同库并存的其他运行(迁移批跑/另一开发机)互不可见
@@ -107,6 +108,7 @@ async def _record_minimal(
         "cached_prompt_tokens": None,
         "model_reported": None,
         "sampling": None,
+        "reasoning_tokens": None,
     }
     fields.update(overrides)
     await recorder.record_llm_call(**fields)
diff --git a/tests/unit/test_openai_compat.py b/tests/unit/test_openai_compat.py
index 5bce879..973cc59 100644
--- a/tests/unit/test_openai_compat.py
+++ b/tests/unit/test_openai_compat.py
@@ -394,6 +394,81 @@ class TestObservabilityFields:
         assert set(result.raw) == {"usage"}
 
 
+class TestReasoningTokens:
+    """issue #6: 推理消耗的输出 token,与 issue #3 的 cached_tokens 对称。
+
+    实测三家供应商在"未推理"时是整个 completion_tokens_details 缺失,无人上报
+    0;且中转在上游不返回 usage 时会本地补算并吃掉该对象。故 None 的语义是
+    "本次调用未上报",不是"该源不上报"(findings §4c)。
+    """
+
+    def _reasoning_usage(self, reasoning):
+        return {**_USAGE, "completion_tokens_details": {"reasoning_tokens": reasoning}}
+
+    async def test_stream_reads_reasoning_tokens(self):
+        def handler(request):
+            return _sse_stream(_chunk(content="ok"), _chunk(usage=self._reasoning_usage(7)))
+
+        result = await _complete(_transport_for(handler), _source())
+        assert result.reasoning_tokens == 7
+
+    async def test_non_stream_reads_reasoning_tokens(self):
+        def handler(request):
+            return httpx.Response(
+                200,
+                json={
+                    "choices": [{"message": {"content": "42"}}],
+                    "usage": self._reasoning_usage(7),
+                },
+            )
+
+        result = await _complete(_transport_for(handler), _source(), stream=False)
+        assert result.reasoning_tokens == 7
+
+    async def test_zero_reasoning_tokens_is_a_real_zero(self):
+        """0(上报了且确实没推理)与 None(本次未上报)必须可区分。"""
+
+        def handler(request):
+            return _sse_stream(_chunk(content="ok"), _chunk(usage=self._reasoning_usage(0)))
+
+        result = await _complete(_transport_for(handler), _source())
+        assert result.reasoning_tokens == 0
+
+    async def test_usage_without_details_is_none(self):
+        def handler(request):
+            return _sse_stream(_chunk(content="ok"), _chunk(usage=_USAGE))
+
+        result = await _complete(_transport_for(handler), _source())
+        assert result.reasoning_tokens is None
+
+    @pytest.mark.parametrize("bad", ["abc", -1, True, 1.5, None, [], {"x": 1}])
+    async def test_malformed_reasoning_tokens_degrade_to_none(self, bad):
+        """`True` 必须排除: Python 里 isinstance(True, int) 为真。"""
+
+        def handler(request):
+            return _sse_stream(_chunk(content="ok"), _chunk(usage=self._reasoning_usage(bad)))
+
+        result = await _complete(_transport_for(handler), _source())
+        assert result.reasoning_tokens is None
+
+    async def test_details_not_a_dict_is_none(self):
+        def handler(request):
+            usage = {**_USAGE, "completion_tokens_details": "oops"}
+            return _sse_stream(_chunk(content="ok"), _chunk(usage=usage))
+
+        result = await _complete(_transport_for(handler), _source())
+        assert result.reasoning_tokens is None
+
+    async def test_salvage_path_records_none_not_zero(self):
+        """打捞路径拿不到 usage 帧: 记 None(未知)而非 0(确定没推理)。"""
+
+        def handler(request):
+            return _sse_stream(_chunk(content="ok"), done=False)
+
+        result = await _complete(_transport_for(handler), _source(missing_done="salvage"))
+        assert result.reasoning_tokens is None
+
+
 class TestNonStreamFastPath:
     async def test_non_stream_parses_message(self):
         def handler(request):
diff --git a/tests/unit/test_ports.py b/tests/unit/test_ports.py
index 74bb5f9..fe722eb 100644
--- a/tests/unit/test_ports.py
+++ b/tests/unit/test_ports.py
@@ -117,6 +117,7 @@ class _DummyRecorder:
         cached_prompt_tokens,
         model_reported,
         sampling,
+        reasoning_tokens,
     ) -> None: ...
 
 
diff --git a/tests/unit/test_retry.py b/tests/unit/test_retry.py
index bb54ae9..affce44 100644
--- a/tests/unit/test_retry.py
+++ b/tests/unit/test_retry.py
@@ -209,11 +209,13 @@ class TestObservabilityPassthrough:
             raw={},
             cached_prompt_tokens=64,
             model_reported="MiniMax-Text-01-250321",
+            reasoning_tokens=7,
         )
         mw, *_ = _harness([_src("a")], [result])
         resp = await mw(_REQ)
         assert resp.cached_prompt_tokens == 64
         assert resp.model_reported == "MiniMax-Text-01-250321"
+        assert resp.reasoning_tokens == 7
         # model 仍是配置别名: 真实版本是旁证,不顶替溯源主字段
         assert resp.model == "m"
 
@@ -221,6 +223,7 @@ class TestObservabilityPassthrough:
         mw, *_ = _harness([_src("a")], [_ok()])
         resp = await mw(_REQ)
         assert resp.cached_prompt_tokens is None and resp.model_reported is None
+        assert resp.reasoning_tokens is None
 
 
 class TestRetryAndFailover:
diff --git a/tests/unit/test_telemetry.py b/tests/unit/test_telemetry.py
index 25128af..5a2df3c 100644
--- a/tests/unit/test_telemetry.py
+++ b/tests/unit/test_telemetry.py
@@ -1,4 +1,4 @@
-"""遥测子系统测试: SQLiteRecorder(21 列)+ TelemetryEmitter 单一 helper + TelemetryMW。"""
+"""遥测子系统测试: SQLiteRecorder(22 列)+ TelemetryEmitter 单一 helper + TelemetryMW。"""
 
 import asyncio
 import json
@@ -39,6 +39,7 @@ _EXPECTED_COLUMNS = [
     "cached_prompt_tokens",
     "model_reported",
     "sampling",
+    "reasoning_tokens",
 ]
 
 
@@ -102,6 +103,7 @@ async def _record_minimal(recorder, call_id="c1", **overrides):
         "cached_prompt_tokens": None,
         "model_reported": None,
         "sampling": None,
+        "reasoning_tokens": None,
     }
     fields.update(overrides)
     await recorder.record_llm_call(**fields)
@@ -158,6 +160,22 @@ class TestSQLiteRecorder:
         assert rows["c-zero"] == 0  # 真实零命中,读回仍是 0 而非 NULL
         assert rows["c-none"] is None
 
+    async def test_reasoning_tokens_column_round_trip(self, tmp_path):
+        """issue #6: 7 / 0 / None 三种值各自如实落库,0 与 NULL 不得混同。"""
+        recorder = SQLiteRecorder(tmp_path / "t.db")
+        await _record_minimal(recorder, call_id="r-some", reasoning_tokens=7)
+        await _record_minimal(recorder, call_id="r-zero", reasoning_tokens=0)
+        await _record_minimal(recorder, call_id="r-none", reasoning_tokens=None)
+        recorder.close()
+        rows = dict(
+            sqlite3.connect(tmp_path / "t.db")
+            .execute("SELECT call_id, reasoning_tokens FROM llm_calls")
+            .fetchall()
+        )
+        assert rows["r-some"] == 7
+        assert rows["r-zero"] == 0  # 上报了且确实没推理
+        assert rows["r-none"] is None  # 本次调用未上报
+
     async def test_sampling_column_round_trips(self, tmp_path):
         """issue #4: 采样参数落库,否则事后无法证明某批数据跑在什么温度下。"""
         recorder = SQLiteRecorder(tmp_path / "t.db")
@@ -284,6 +302,7 @@ class TestPostgresBackfillDiscipline:
         "cached_prompt_tokens",
         "model_reported",
         "sampling",
+        "reasoning_tokens",
     ]
 
     def _recorder(self, conn):
@@ -384,11 +403,12 @@ class TestEmitterObservabilityFields:
             source=_source(),
             call_id="cid-1",
             latency_ms=42,
-            response=_resp(cached_prompt_tokens=64, model_reported="m-real"),
+            response=_resp(cached_prompt_tokens=64, model_reported="m-real", reasoning_tokens=7),
             error=None,
         )
         assert rec.rows[0]["cached_prompt_tokens"] == 64
         assert rec.rows[0]["model_reported"] == "m-real"
+        assert rec.rows[0]["reasoning_tokens"] == 7
 
     async def test_failed_attempt_has_no_provider_facts(self):
         rec = _MemoryRecorder()
@@ -402,16 +422,19 @@ class TestEmitterObservabilityFields:
         )
         assert rec.rows[0]["cached_prompt_tokens"] is None
         assert rec.rows[0]["model_reported"] is None
+        assert rec.rows[0]["reasoning_tokens"] is None
 
     async def test_cache_hit_replays_the_recorded_values(self):
         """决策 B1: 命中行原样回放,故命中率统计必须带 WHERE cache_hit = false。"""
         rec = _MemoryRecorder()
         await TelemetryEmitter(rec).emit_cache_hit(
-            request=_REQ, response=_resp(cached_prompt_tokens=64, model_reported="m-real")
+            request=_REQ,
+            response=_resp(cached_prompt_tokens=64, model_reported="m-real", reasoning_tokens=7),
         )
         row = rec.rows[0]
         assert row["cache_hit"] is True
         assert row["cached_prompt_tokens"] == 64 and row["model_reported"] == "m-real"
+        assert row["reasoning_tokens"] == 7  # 与 cached 同口径原样回放
 
     async def test_terminal_failure_records_none(self):
         rec = _MemoryRecorder()
@@ -420,6 +443,7 @@ class TestEmitterObservabilityFields:
         )
         assert rec.rows[0]["cached_prompt_tokens"] is None
         assert rec.rows[0]["model_reported"] is None
+        assert rec.rows[0]["reasoning_tokens"] is None
 
 
 class TestEmitterSamplingColumn:
diff --git a/tests/unit/test_types.py b/tests/unit/test_types.py
index 1eae3b8..de288c1 100644
--- a/tests/unit/test_types.py
+++ b/tests/unit/test_types.py
@@ -54,6 +54,7 @@ class TestLLMResponse:
         resp = LLMResponse("c", "t", "m", "p", 1, 2, 3, None, None, False, "cid")
         assert resp.cached_prompt_tokens is None
         assert resp.model_reported is None
+        assert resp.reasoning_tokens is None  # issue #6: 本次调用未上报
         filled = LLMResponse(
             "c",
             "t",
@@ -68,9 +69,11 @@ class TestLLMResponse:
             "cid",
             cached_prompt_tokens=0,
             model_reported="MiniMax-Text-01-250321",
+            reasoning_tokens=0,
         )
         assert filled.cached_prompt_tokens == 0  # 真实零命中,不得与 None 混同
         assert filled.model_reported == "MiniMax-Text-01-250321"
+        assert filled.reasoning_tokens == 0  # 上报了且确实没推理,不得与 None 混同
 
     def test_frozen(self):
         resp = LLMResponse("c", "t", "m", "p", 1, 2, 3, None, None, False, "cid")
@@ -247,6 +250,7 @@ class TestAuxTypes:
         assert s.raw["id"] == "x"
         # issue #3: 新字段带默认值,不填也能构造(OCR 等其他 transport 零改动)
         assert s.cached_prompt_tokens is None and s.model_reported is None
+        assert s.reasoning_tokens is None
 
 
 class TestOcrTypes: