refactor: 将 adapter 层的计费/模型抓取/行为变体能力下沉到 core.api_format 注册表

- 新增 core/api_format/capabilities.py，统一注册计费模板、模型抓取、
  total_input_context 计算和 provider behavior variant
- 新增 core/usage_tokens.py，抽取 cache token 解析逻辑到 core 层
- handler adapter 移除各自的 compute_total_input_context / fetch_models /
  BILLING_TEMPLATE 覆盖，改为委托 core 注册表解析
- provider/behavior.py 改为薄封装，底层委托 core registry
- 新增 tests/test_architecture_import_rules.py 架构导入约束测试
- 新增 tests/services/api_format/test_capabilities.py 能力注册表测试

Closes #207

Co-authored-by: AAEE86 <ppk0227@hotmail.com>

tests/services/api_format/test_capabilities.py

@@ -0,0 +1,109 @@
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+from types import SimpleNamespace
+from unittest.mock import AsyncMock
+
+import pytest
+
+ROOT = Path(__file__).resolve().parents[3]
+if str(ROOT) not in sys.path:
+    sys.path.insert(0, str(ROOT))
+
+from src.core.api_format.capabilities import (
+    compute_total_input_context_for_api_format,
+    fetch_models_for_api_format,
+    get_provider_default_body_rules,
+    register_provider_default_body_rules,
+    register_provider_format_behavior,
+    resolve_billing_template_for_api_format,
+)
+from src.core.api_format.metadata import get_default_body_rules_for_endpoint
+from src.services.provider.behavior import get_provider_behavior
+
+
+class _DummyResp:
+    def __init__(self, status_code: int, payload: object, text: str = "") -> None:
+        self.status_code = status_code
+        self.payload = payload
+        self.text = text
+
+    def json(self) -> object:
+        return self.payload
+
+
+def test_api_format_capability_billing_mapping() -> None:
+    assert resolve_billing_template_for_api_format("openai:cli") == "openai"
+    assert resolve_billing_template_for_api_format("claude:chat") == "claude"
+    assert resolve_billing_template_for_api_format("gemini:cli") == "gemini"
+
+
+def test_provider_default_body_rules_use_unified_registry() -> None:
+    provider_type = "unit_test_provider_rules"
+    expected = [{"action": "drop", "path": "foo"}]
+    register_provider_default_body_rules(provider_type, "openai:cli", expected)
+
+    rules = get_provider_default_body_rules(provider_type, "openai:cli")
+    assert rules == expected
+    assert (
+        get_default_body_rules_for_endpoint("openai:cli", provider_type=provider_type) == expected
+    )
+
+
+def test_provider_behavior_variants_use_unified_registry() -> None:
+    provider_type = "unit_test_variant_provider"
+    register_provider_format_behavior(
+        provider_type,
+        same_format_variant="same-unit",
+        cross_format_variant="cross-unit",
+    )
+
+    behavior = get_provider_behavior(provider_type=provider_type, endpoint_sig="openai:cli")
+    assert behavior.same_format_variant == "same-unit"
+    assert behavior.cross_format_variant == "cross-unit"
+
+
+def test_api_format_capability_total_input_context() -> None:
+    assert compute_total_input_context_for_api_format("openai:chat", 100, 20, 30) == 120
+    assert compute_total_input_context_for_api_format("claude:chat", 100, 20, 30) == 150
+
+
+@pytest.mark.asyncio
+async def test_fetch_models_uses_registered_claude_strategy() -> None:
+    client = SimpleNamespace(
+        get=AsyncMock(
+            side_effect=[
+                _DummyResp(
+                    status_code=200,
+                    payload={
+                        "data": [{"id": "m1"}, {"id": "m2"}],
+                        "has_more": True,
+                        "last_id": "m2",
+                    },
+                ),
+                _DummyResp(
+                    status_code=200,
+                    payload={
+                        "data": [{"id": "m3"}],
+                        "has_more": False,
+                        "last_id": "m3",
+                    },
+                ),
+            ]
+        )
+    )
+
+    models, err = await fetch_models_for_api_format(
+        client,  # type: ignore[arg-type]
+        api_format="claude:chat",
+        base_url="https://api.anthropic.com",
+        api_key="k",
+    )
+
+    assert err is None
+    assert [m.get("id") for m in models] == ["m1", "m2", "m3"]
+    assert all(m.get("api_format") == "claude:chat" for m in models)
+    assert client.get.call_count == 2
+    _, kwargs2 = client.get.call_args_list[1]
+    assert kwargs2.get("params", {}).get("after_id") == "m2"

tests/services/test_provider_keys_key_command_service.py

@@ -178,11 +178,13 @@ def test_clear_oauth_invalid_response_invalidates_caches(
         sys.modules, "src.services.cache.provider_cache", fake_provider_cache_module
     )
 
-    fake_models_service_module = types.ModuleType("src.api.base.models_service")
+    fake_models_service_module = types.ModuleType("src.services.cache.model_list_cache")
     setattr(
         fake_models_service_module, "invalidate_models_list_cache", _fake_invalidate_models_cache
     )
-    monkeypatch.setitem(sys.modules, "src.api.base.models_service", fake_models_service_module)
+    monkeypatch.setitem(
+        sys.modules, "src.services.cache.model_list_cache", fake_models_service_module
+    )
 
     key = SimpleNamespace(
         oauth_invalid_at=datetime.now(timezone.utc),