feat: model the thinking switch as shape plus capability (issue #5)

enable_thinking=False was a no-op for minimax and openai sources: both
profiles had empty dicts on each side, so the payload update injected
nothing while the caller believed reasoning had been turned off. A
downstream project was blocked on exactly this.

The root cause is that an empty dict meant two different things -- "no
injection needed" and "we do not know how this provider spells it" --
and that a provider-level table cannot express what turned out to be a
per-model property. Live testing showed MiniMax-M3 can disable
reasoning via reasoning_effort while M2.7 and M2.5 cannot be disabled
at all, which two external registries independently confirm.

So the shape stays at provider level and a capability table joins it at
model level. Unknown, unsupported and no-opinion are now three distinct
values, and resolve_thinking is the single place they meet: it raises at
assembly time when a model cannot honour the request, warns and injects
for unregistered models, and injects silently otherwise. Every registered
capability carries the evidence it was derived from.

enable_thinking also joins the cache fingerprint, since it now really
does change the request body.

tests/unit/test_providers.py

@@ -1,12 +1,18 @@
 """providers.py 注册表测试(M1 设计 §7;register_provider 为纯函数,无可变全局)。"""
 
 import pytest
+from loguru import logger
 
 from polygateway.providers import (
+    DEFAULT_CAPABILITIES,
     DEFAULT_PROFILES,
     ProviderProfile,
+    ThinkingCapability,
+    get_capability,
     get_provider,
+    register_capability,
     register_provider,
+    resolve_thinking,
 )
 
 
@@ -24,14 +30,21 @@ class TestDefaultProfiles:
         assert p.thinking_off == {"thinking": {"type": "disabled"}}
         assert p.strip_think_tags is False
 
-    def test_openai_baseline_profile(self):
+    def test_openai_slots_are_unknown_not_empty(self):
+        """issue #5: 该段名实践中被复用为任意兼容厂商的兜底(下游把 kimi 挂在此),
+
+        故不能下发任何厂商方言参数。None = 形态未知 → 配了 enable_thinking 即报错,
+        而不是空字典那种"注入了个寂寞"的静默失效。
+        """
         p = get_provider("openai")
-        assert p.thinking_on == {} and p.thinking_off == {}
+        assert p.thinking_on is None and p.thinking_off is None
         assert p.strip_think_tags is False
 
-    def test_minimax_baseline_profile(self):
+    def test_minimax_profile_uses_reasoning_effort(self):
+        """2026-08-02 实测: reasoning_effort 才是 MiniMax 认的开关。"""
         p = get_provider("minimax")
-        assert p.thinking_on == {} and p.thinking_off == {}
+        assert p.thinking_off == {"reasoning_effort": "none"}
+        assert p.thinking_on == {"reasoning_effort": "medium"}
         assert p.strip_think_tags is False
 
     def test_unknown_provider_fails_loudly(self):
@@ -62,3 +75,83 @@ class TestPureFunctionRegistration:
     def test_default_profiles_mapping_is_read_only(self):
         with pytest.raises(TypeError):
             DEFAULT_PROFILES["hack"] = None  # type: ignore[index]
+
+
+def _warnings():
+    """捕获库发出的 WARNING;loguru 不经标准 logging,pytest 的 caplog 抓不到。"""
+    messages: list[str] = []
+    sink_id = logger.add(messages.append, level="WARNING")
+    return messages, sink_id
+
+
+class TestThinkingCapability:
+    """issue #5: 能力按 model 登记——同一 provider 内部代际差异是决定性的。"""
+
+    def test_registered_models_carry_evidence(self):
+        """登记必须附实测证据: 表会过期,没有出处就无从判断该不该信。"""
+        for model in ("MiniMax-M3", "MiniMax-M2.7", "MiniMax-M2.5"):
+            cap = get_capability(model)
+            assert cap is not None and cap.evidence.strip()
+
+    def test_m3_can_disable_but_m2x_cannot(self):
+        assert get_capability("MiniMax-M3").can_disable is True
+        assert get_capability("MiniMax-M2.7").can_disable is False
+        assert get_capability("MiniMax-M2.5").can_disable is False
+
+    def test_unregistered_model_is_unknown(self):
+        assert get_capability("some-brand-new-model") is None
+
+    def test_register_capability_is_pure(self):
+        table = register_capability("x-1", ThinkingCapability(True, "实测"))
+        assert get_capability("x-1", table=table) is not None
+        assert get_capability("x-1") is None  # 默认表未被污染
+
+    def test_default_capabilities_mapping_is_read_only(self):
+        with pytest.raises(TypeError):
+            DEFAULT_CAPABILITIES["hack"] = None  # type: ignore[index]
+
+
+class TestResolveThinking:
+    """五条判定规则(顺序即语义);设计 §5 真值表。"""
+
+    def test_rule1_none_injects_nothing(self):
+        got = resolve_thinking(get_provider("minimax"), None, None, model="MiniMax-M3")
+        assert got == {}
+
+    @pytest.mark.parametrize("enable", [True, False])
+    def test_rule2_unknown_shape_raises_and_points_the_way(self, enable):
+        with pytest.raises(ValueError, match="register_provider") as exc:
+            resolve_thinking(get_provider("openai"), None, enable, model="kimi-k3")
+        assert "extra_body" in str(exc.value)
+
+    def test_rule3_unregistered_model_warns_but_passes(self):
+        messages, sink_id = _warnings()
+        try:
+            got = resolve_thinking(get_provider("minimax"), None, False, model="MiniMax-M9")
+        finally:
+            logger.remove(sink_id)
+        assert got == {"reasoning_effort": "none"}
+        assert any("MiniMax-M9" in m for m in messages)
+
+    def test_rule4_cannot_disable_raises_with_the_model_name(self):
+        cap = get_capability("MiniMax-M2.7")
+        with pytest.raises(ValueError, match="MiniMax-M2.7"):
+            resolve_thinking(get_provider("minimax"), cap, False, model="MiniMax-M2.7")
+
+    def test_rule4_only_blocks_the_off_direction(self):
+        """关不掉 ≠ 开不了: M2.x 默认就在推理,开的方向不该被拦。"""
+        cap = get_capability("MiniMax-M2.7")
+        got = resolve_thinking(get_provider("minimax"), cap, True, model="MiniMax-M2.7")
+        assert got == {"reasoning_effort": "medium"}
+
+    def test_rule5_normal_path(self):
+        cap = get_capability("MiniMax-M3")
+        assert resolve_thinking(get_provider("minimax"), cap, False, model="MiniMax-M3") == {
+            "reasoning_effort": "none"
+        }
+
+    def test_unknown_shape_beats_capability_check(self):
+        """第 2 步先于第 4 步: 形态未知时无从注入,能力如何无关紧要。"""
+        cap = ThinkingCapability(can_disable=False, evidence="构造")
+        with pytest.raises(ValueError, match="register_provider"):
+            resolve_thinking(get_provider("openai"), cap, False, model="whatever")