fix(gemini): tighten native routing and streaming replay

- only use the native adapter for the canonical Gemini native endpoint
- keep custom and /openai base URLs on the OpenAI-compatible path
- preserve Hermes keepalive transport injection for native Gemini clients
- stabilize streaming tool-call replay across repeated SSE events
- add follow-up tests for base_url precedence, async streaming, and duplicate tool-call chunks

agent/gemini_native_adapter.py

@@ -32,6 +32,16 @@ logger = logging.getLogger(__name__)
 DEFAULT_GEMINI_BASE_URL = "https://generativelanguage.googleapis.com/v1beta"
 
 
+def is_native_gemini_base_url(base_url: str) -> bool:
+    """Return True when the endpoint speaks Gemini's native REST API."""
+    normalized = str(base_url or "").strip().rstrip("/").lower()
+    if not normalized:
+        return False
+    if "generativelanguage.googleapis.com" not in normalized:
+        return False
+    return not normalized.endswith("/openai")
+
+
 class GeminiAPIError(Exception):
     """Error shape compatible with Hermes retry/error classification."""
 
@@ -520,7 +530,7 @@ def translate_stream_event(event: Dict[str, Any], model: str, tool_call_indices:
     parts = ((cand.get("content") or {}).get("parts") or []) if isinstance(cand, dict) else []
     chunks: List[_GeminiStreamChunk] = []
 
-    for part in parts:
+    for part_index, part in enumerate(parts):
         if not isinstance(part, dict):
             continue
         if part.get("thought") is True and isinstance(part.get("text"), str):
@@ -536,14 +546,30 @@ def translate_stream_event(event: Dict[str, Any], model: str, tool_call_indices:
             except (TypeError, ValueError):
                 args_str = "{}"
             thought_signature = part.get("thoughtSignature") if isinstance(part.get("thoughtSignature"), str) else ""
-            call_key = json.dumps({"name": name, "args": args_str, "thought_signature": thought_signature}, sort_keys=True)
+            call_key = json.dumps(
+                {
+                    "part_index": part_index,
+                    "name": name,
+                    "thought_signature": thought_signature,
+                },
+                sort_keys=True,
+            )
             slot = tool_call_indices.get(call_key)
             if slot is None:
                 slot = {
                     "index": len(tool_call_indices),
                     "id": f"call_{uuid.uuid4().hex[:12]}",
+                    "last_arguments": "",
                 }
                 tool_call_indices[call_key] = slot
+            emitted_arguments = args_str
+            last_arguments = str(slot.get("last_arguments") or "")
+            if last_arguments:
+                if args_str == last_arguments:
+                    emitted_arguments = ""
+                elif args_str.startswith(last_arguments):
+                    emitted_arguments = args_str[len(last_arguments):]
+            slot["last_arguments"] = args_str
             chunks.append(
                 _make_stream_chunk(
                     model=model,
@@ -551,7 +577,7 @@ def translate_stream_event(event: Dict[str, Any], model: str, tool_call_indices:
                         "index": slot["index"],
                         "id": slot["id"],
                         "name": name,
-                        "arguments": args_str,
+                        "arguments": emitted_arguments,
                         "extra_content": _tool_call_extra_from_part(part),
                     },
                 )
@@ -672,6 +698,7 @@ class GeminiNativeClient:
         base_url: Optional[str] = None,
         default_headers: Optional[Dict[str, str]] = None,
         timeout: Any = None,
+        http_client: Optional[httpx.Client] = None,
         **_: Any,
     ) -> None:
         self.api_key = api_key
@@ -682,7 +709,9 @@ class GeminiNativeClient:
         self._default_headers = dict(default_headers or {})
         self.chat = _GeminiChatNamespace(self)
         self.is_closed = False
-        self._http = httpx.Client(timeout=timeout or httpx.Timeout(connect=15.0, read=600.0, write=30.0, pool=30.0))
+        self._http = http_client or httpx.Client(
+            timeout=timeout or httpx.Timeout(connect=15.0, read=600.0, write=30.0, pool=30.0)
+        )
 
     def close(self) -> None:
         self.is_closed = True
@@ -707,6 +736,13 @@ class GeminiNativeClient:
         headers.update(self._default_headers)
         return headers
 
+    @staticmethod
+    def _advance_stream_iterator(iterator: Iterator[_GeminiStreamChunk]) -> tuple[bool, Optional[_GeminiStreamChunk]]:
+        try:
+            return False, next(iterator)
+        except StopIteration:
+            return True, None
+
     def _create_chat_completion(
         self,
         *,
@@ -767,7 +803,7 @@ class GeminiNativeClient:
                     if response.status_code != 200:
                         response.read()
                         raise gemini_http_error(response)
-                    tool_call_indices: Dict[str, int] = {}
+                    tool_call_indices: Dict[str, Dict[str, Any]] = {}
                     for event in _iter_sse_events(response):
                         for chunk in translate_stream_event(event, model, tool_call_indices):
                             yield chunk
@@ -790,7 +826,19 @@ class AsyncGeminiNativeClient:
         self.chat = _AsyncGeminiChatNamespace(self)
 
     async def _create_chat_completion(self, **kwargs: Any) -> Any:
-        return await asyncio.to_thread(self._sync.chat.completions.create, **kwargs)
+        stream = bool(kwargs.get("stream"))
+        result = await asyncio.to_thread(self._sync.chat.completions.create, **kwargs)
+        if not stream:
+            return result
+
+        async def _async_stream() -> Any:
+            while True:
+                done, chunk = await asyncio.to_thread(self._sync._advance_stream_iterator, result)
+                if done:
+                    break
+                yield chunk
+
+        return _async_stream()
 
     async def close(self) -> None:
         await asyncio.to_thread(self._sync.close)