feat: Antigravity 和 Codex 服务支持

- 新增 Antigravity 服务：签名缓存、URL 可用性检测、信封处理
- 新增 Codex 服务：信封处理、元数据收集器
- 重构 provider transport 支持新的服务架构
- 新增 stream_bridge 和 upstream_stream_bridge 处理流式响应
- 优化 OAuth 工具函数
- 添加相关测试用例

tests/api/handlers/base/test_antigravity_v1internal.py

@@ -0,0 +1,201 @@
+from __future__ import annotations
+
+import json
+from types import SimpleNamespace
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+from src.services.antigravity.envelope import (
+    unwrap_v1internal_response,
+    wrap_v1internal_request,
+)
+from src.api.handlers.base.stream_context import StreamContext
+from src.api.handlers.gemini_cli.handler import GeminiCliMessageHandler
+
+
+def _make_handler() -> GeminiCliMessageHandler:
+    return GeminiCliMessageHandler(
+        db=MagicMock(),
+        user=SimpleNamespace(id=1),
+        api_key=SimpleNamespace(id=1),
+        request_id="req_1",
+        client_ip="127.0.0.1",
+        user_agent="pytest",
+        start_time=0.0,
+    )
+
+
+def test_wrap_v1internal_request_removes_inner_model() -> None:
+    gemini_request = {
+        "model": "gemini-2.0-flash",
+        "contents": [{"role": "user", "parts": [{"text": "hi"}]}],
+    }
+
+    wrapped = wrap_v1internal_request(
+        gemini_request,
+        project_id="project-123",
+        model="gemini-2.0-flash",
+    )
+
+    assert wrapped["project"] == "project-123"
+    assert wrapped["model"] == "gemini-2.0-flash"
+    assert "request" in wrapped
+    assert "model" not in wrapped["request"]
+
+
+def test_unwrap_v1internal_response() -> None:
+    v1_resp = {
+        "response": {"candidates": [{"content": {"parts": [{"text": "Hello"}]}}]},
+        "responseId": "resp-123",
+    }
+
+    unwrapped = unwrap_v1internal_response(v1_resp)
+
+    assert "response" not in unwrapped
+    assert "candidates" in unwrapped
+    assert unwrapped["_v1internal_response_id"] == "resp-123"
+
+
+def test_convert_sse_line_unwraps_before_convert_stream_chunk() -> None:
+    handler = _make_handler()
+
+    ctx = StreamContext(model="gemini-2.0-flash", api_format="gemini:cli")
+    ctx.provider_type = "antigravity"
+    ctx.provider_api_format = "gemini:cli"
+    ctx.client_api_format = "gemini:cli"
+
+    v1_line = (
+        'data: {"response": {"candidates": [{"content": {"parts": [{"text": "Hi"}]}}]},'
+        ' "responseId": "123"}'
+    )
+
+    seen: dict[str, object] = {}
+
+    class _DummyRegistry:
+        def convert_stream_chunk(self, data_obj, *_args, **_kwargs):  # noqa: ANN001
+            seen["data_obj"] = data_obj
+            return []
+
+    with patch(
+        "src.api.handlers.base.cli_handler_base.get_format_converter_registry",
+        return_value=_DummyRegistry(),
+    ):
+        _lines, _events = handler._convert_sse_line(ctx, v1_line, [])
+
+    assert isinstance(seen.get("data_obj"), dict)
+    assert "response" not in seen["data_obj"]  # 已解包
+    assert "_v1internal_response_id" in seen["data_obj"]
+
+
+def test_handle_sse_event_unwraps_for_antigravity() -> None:
+    handler = _make_handler()
+
+    ctx = StreamContext(model="gemini-2.0-flash", api_format="gemini:cli")
+    ctx.provider_type = "antigravity"
+
+    v1_data = {
+        "response": {
+            "candidates": [
+                {
+                    "content": {"parts": [{"text": "Hello"}], "role": "model"},
+                    "finishReason": "STOP",
+                }
+            ],
+            "modelVersion": "gemini-2.0-flash-001",
+        },
+        "responseId": "123",
+    }
+
+    with patch.object(handler, "_process_event_data") as mock_process:
+        handler._handle_sse_event(ctx, None, json.dumps(v1_data), record_chunk=False)
+
+    assert mock_process.call_count == 1
+    passed_data = mock_process.call_args[0][2]
+    assert isinstance(passed_data, dict)
+    assert "response" not in passed_data
+    assert "candidates" in passed_data
+
+
+def test_handle_sse_event_caches_thought_signature_for_antigravity() -> None:
+    from src.services.antigravity.signature_cache import signature_cache
+
+    signature_cache._cache.clear()  # type: ignore[attr-defined]
+
+    handler = _make_handler()
+    ctx = StreamContext(model="claude-sonnet-4-5", api_format="gemini:cli")
+    ctx.provider_type = "antigravity"
+
+    payload = {
+        "candidates": [
+            {
+                "content": {
+                    "parts": [
+                        {
+                            "text": "t1",
+                            "thought": True,
+                            "thoughtSignature": "sig-abc",
+                        }
+                    ]
+                }
+            }
+        ]
+    }
+
+    with patch.object(handler, "_process_event_data") as _mock_process:
+        handler._handle_sse_event(ctx, None, json.dumps(payload), record_chunk=False)
+
+    assert signature_cache.get_or_dummy("claude-sonnet-4-5", "t1") == "sig-abc"
+
+
+def test_provider_type_drives_antigravity_usage_path() -> None:
+    handler = _make_handler()
+
+    event = {"usageMetadata": {"promptTokenCount": 10, "candidatesTokenCount": 2}}
+    usage = handler._extract_usage_from_event(event, provider_type="antigravity")
+
+    assert usage["input_tokens"] == 10
+    assert usage["output_tokens"] == 2
+
+
+@pytest.mark.asyncio
+async def test_antigravity_forces_conversion_path_in_stream_with_prefetch() -> None:
+    handler = _make_handler()
+
+    ctx = StreamContext(model="gemini-2.0-flash", api_format="gemini:cli")
+    ctx.provider_type = "antigravity"
+    ctx.needs_conversion = False  # same-format case normally would passthrough
+
+    class _AsyncIter:
+        def __init__(self, items):  # noqa: ANN001
+            self._it = iter(items)
+
+        def __aiter__(self):
+            return self
+
+        async def __anext__(self):
+            try:
+                return next(self._it)
+            except StopIteration as e:
+                raise StopAsyncIteration from e
+
+    prefetched = [
+        b'data: {"response": {"candidates": []}, "responseId": "1"}\n',
+    ]
+    byte_iter = _AsyncIter([])  # no more bytes after prefetch
+    response_ctx = SimpleNamespace(__aexit__=AsyncMock(return_value=None))
+    http_client = SimpleNamespace(aclose=AsyncMock(return_value=None))
+
+    with patch.object(
+        handler,
+        "_convert_sse_line",
+        return_value=(["data: {}"], []),
+    ) as mock_convert:
+        out = []
+        async for chunk in handler._create_response_stream_with_prefetch(
+            ctx, byte_iter, response_ctx, http_client, prefetched
+        ):
+            out.append(chunk)
+
+    assert mock_convert.call_count >= 1
+    assert any(b"data: {}" in c for c in out)