fix(cli): use UTF-8 for config files

src/openjarvis/cli/config_cmd.py

@@ -158,7 +158,7 @@ def _show_toml_config(console: Console, config_path: Path) -> None:
     console.print(f"[dim]Loading config from: {config_path}[/dim]")
 
     if config_path.exists():
-        config_content = config_path.read_text()
+        config_content = config_path.read_text(encoding="utf-8")
         syntax = Syntax(config_content, "toml", theme="monokai", line_numbers=True)
         console.print(Panel(syntax, title="Config File", border_style="cyan"))
     else:
@@ -170,7 +170,7 @@ def _show_json_config(console: Console, config_path: Path) -> None:
     console.print(f"[dim]Loading config from: {config_path}[/dim]")
 
     if config_path.exists():
-        config_content = config_path.read_text()
+        config_content = config_path.read_text(encoding="utf-8")
 
         try:
             import tomllib  # Python 3.11+
@@ -375,7 +375,7 @@ def set_config(key: str, value: str) -> None:
         os.environ.get("OPENJARVIS_CONFIG", DEFAULT_CONFIG_DIR / "config.toml")
     )
     if config_path.exists():
-        doc = tomlkit.parse(config_path.read_text())
+        doc = tomlkit.parse(config_path.read_text(encoding="utf-8"))
     else:
         doc = tomlkit.document()
         config_path.parent.mkdir(parents=True, exist_ok=True)
@@ -390,7 +390,7 @@ def set_config(key: str, value: str) -> None:
     current[parts[-1]] = typed_value
 
     # Write back
-    config_path.write_text(tomlkit.dumps(doc))
+    config_path.write_text(tomlkit.dumps(doc), encoding="utf-8")
 
     console.print(f"[green]Set[/green] {key} = {value!r}")
 

src/openjarvis/cli/init_cmd.py

@@ -344,7 +344,9 @@ def init(
             console.print(f"  Looked in: {examples_dir}")
             raise SystemExit(1)
         DEFAULT_CONFIG_DIR.mkdir(parents=True, exist_ok=True)
-        DEFAULT_CONFIG_PATH.write_text(preset_path.read_text())
+        DEFAULT_CONFIG_PATH.write_text(
+            preset_path.read_text(encoding="utf-8"), encoding="utf-8"
+        )
         console.print(
             f"[green]Preset '{preset}' installed to {DEFAULT_CONFIG_PATH}[/green]"
         )

src/openjarvis/engine/cloud.py

@@ -9,6 +9,7 @@ import json
 import logging
 import os
 import time
+import uuid
 from collections.abc import AsyncIterator, Sequence
 from typing import Any, Dict, List, Tuple
 
@@ -1305,6 +1306,160 @@ class CloudEngine(InferenceEngine):
             if chunk.text:
                 yield chunk.text
 
+    async def _stream_full_google(
+        self,
+        messages: Sequence[Message],
+        *,
+        model: str,
+        temperature: float,
+        max_tokens: int,
+        **kwargs: Any,
+    ) -> AsyncIterator[StreamChunk]:
+        """Stream Google text and function-call parts as full chunks."""
+        if self._google_client is None:
+            raise EngineConnectionError("Google client not available")
+
+        system_text = ""
+        contents: List[Dict[str, Any]] = []
+        for message in messages:
+            if message.role.value == "system":
+                system_text = message.content
+            elif message.role.value == "tool":
+                function_response = {
+                    "function_response": {
+                        "name": message.name or "unknown",
+                        "response": {"result": message.content},
+                    }
+                }
+                if (
+                    contents
+                    and contents[-1]["role"] == "user"
+                    and contents[-1]["parts"]
+                    and "function_response" in contents[-1]["parts"][-1]
+                ):
+                    contents[-1]["parts"].append(function_response)
+                else:
+                    contents.append({"role": "user", "parts": [function_response]})
+            elif message.role.value == "assistant" and message.tool_calls:
+                parts: List[Dict[str, Any]] = []
+                if message.content:
+                    parts.append({"text": message.content})
+                for tool_call in message.tool_calls:
+                    args = tool_call.arguments
+                    if isinstance(args, str):
+                        try:
+                            args = json.loads(args)
+                        except (json.JSONDecodeError, TypeError):
+                            args = {"input": args}
+                    function_call_part: Dict[str, Any] = {
+                        "function_call": {
+                            "name": tool_call.name,
+                            "args": args if isinstance(args, dict) else {},
+                        }
+                    }
+                    signature = self._thought_sigs.get(tool_call.id)
+                    if signature is not None:
+                        function_call_part["thought_signature"] = signature
+                    parts.append(function_call_part)
+                contents.append({"role": "model", "parts": parts})
+            elif message.role.value == "assistant":
+                contents.append({"role": "model", "parts": [{"text": message.content}]})
+            else:
+                contents.append({"role": "user", "parts": [{"text": message.content}]})
+
+        from google.genai import types as genai_types
+
+        config = genai_types.GenerateContentConfig(
+            temperature=temperature,
+            max_output_tokens=max_tokens,
+        )
+        if system_text:
+            config.system_instruction = system_text
+
+        tools = kwargs.pop("tools", None)
+        if tools:
+            config.tools = [{"function_declarations": _convert_tools_to_google(tools)}]
+
+        tool_call_count = 0
+        stream_id = uuid.uuid4().hex
+        final_usage: Dict[str, Any] | None = None
+        for chunk in self._google_client.models.generate_content_stream(
+            model=model,
+            contents=contents,
+            config=config,
+        ):
+            usage_metadata = getattr(chunk, "usage_metadata", None)
+            if usage_metadata is not None:
+                prompt_tokens = getattr(usage_metadata, "prompt_token_count", 0) or 0
+                completion_tokens = (
+                    getattr(usage_metadata, "candidates_token_count", 0) or 0
+                )
+                final_usage = {
+                    "prompt_tokens": prompt_tokens,
+                    "completion_tokens": completion_tokens,
+                    "total_tokens": prompt_tokens + completion_tokens,
+                }
+
+            candidates = getattr(chunk, "candidates", None)
+            parts = []
+            if candidates:
+                parts = getattr(candidates[0].content, "parts", []) or []
+
+            if parts:
+                text_found = False
+                calls: List[Dict[str, Any]] = []
+                for part in parts:
+                    text = getattr(part, "text", None)
+                    if text:
+                        text_found = True
+                        yield StreamChunk(content=text)
+
+                    function_call = getattr(part, "function_call", None)
+                    if function_call:
+                        name = getattr(function_call, "name", "")
+                        raw_args = getattr(function_call, "args", {})
+                        args = dict(raw_args) if hasattr(raw_args, "items") else {}
+                        # Gemini emits complete function-call parts, so each part is
+                        # a distinct invocation. The same function may legitimately
+                        # be called more than once in a parallel response.
+                        tool_index = tool_call_count
+                        # The engine is shared across server requests, and saved
+                        # thought signatures are keyed by tool-call ID. Include a
+                        # per-stream nonce so concurrent conversations cannot
+                        # overwrite each other's signatures.
+                        tool_id = f"google_{stream_id}_{tool_index}"
+                        tool_call_count += 1
+                        tool_call = {
+                            "index": tool_index,
+                            "id": tool_id,
+                            "type": "function",
+                            "function": {
+                                "name": name,
+                                "arguments": json.dumps(args),
+                            },
+                        }
+                        calls.append(tool_call)
+                        signature = getattr(part, "thought_signature", None)
+                        if signature is not None:
+                            tool_call["thought_signature"] = signature
+                            self._thought_sigs[tool_id] = signature
+                if calls:
+                    yield StreamChunk(tool_calls=calls)
+                if text_found:
+                    continue
+
+            try:
+                text = chunk.text
+            except (AttributeError, ValueError):
+                text = None
+            if text:
+                yield StreamChunk(content=text)
+
+        yield StreamChunk(
+            finish_reason="tool_calls" if tool_call_count else "stop",
+            usage=final_usage,
+        )
+
     async def _stream_openrouter(
         self,
         messages: Sequence[Message],
@@ -1600,7 +1755,7 @@ class CloudEngine(InferenceEngine):
             async for chunk in self._stream_full_anthropic(messages, **kw):
                 yield chunk
         elif _is_google_model(model):
-            async for chunk in super().stream_full(messages, **kw):
+            async for chunk in self._stream_full_google(messages, **kw):
                 yield chunk
         else:
             async for chunk in self._stream_full_openai(messages, **kw):

tests/cli/test_cli.py

@@ -138,6 +138,38 @@ class TestCLI:
         content = config_path.read_text()
         assert "[engine]" in content
 
+    def test_init_preset_uses_utf8_for_config_copy(self, tmp_path: Path) -> None:
+        """Preset installation reads and writes shipped TOML as UTF-8."""
+        config_dir = tmp_path / ".openjarvis"
+        config_path = config_dir / "config.toml"
+        original_read_text = Path.read_text
+        original_write_text = Path.write_text
+
+        def read_text(path: Path, *args: object, **kwargs: object) -> str:
+            if path.name == "chat-simple.toml":
+                assert kwargs.get("encoding") == "utf-8"
+            return original_read_text(path, *args, **kwargs)
+
+        def write_text(path: Path, data: str, *args: object, **kwargs: object) -> int:
+            if path == config_path:
+                assert kwargs.get("encoding") == "utf-8"
+            return original_write_text(path, data, *args, **kwargs)
+
+        with (
+            mock.patch("openjarvis.cli.init_cmd.DEFAULT_CONFIG_DIR", config_dir),
+            mock.patch("openjarvis.cli.init_cmd.DEFAULT_CONFIG_PATH", config_path),
+            mock.patch.object(Path, "read_text", autospec=True, side_effect=read_text),
+            mock.patch.object(
+                Path, "write_text", autospec=True, side_effect=write_text
+            ),
+        ):
+            result = CliRunner().invoke(cli, ["init", "--preset", "chat-simple"])
+
+        assert result.exit_code == 0
+        assert "lightweight conversational AI" in config_path.read_text(
+            encoding="utf-8"
+        )
+
 
 class TestStartupResilience:
     """Importing the CLI must not force heavy/native deps (#404, #309).

tests/cli/test_config_cmd.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import json
 from pathlib import Path
+from unittest import mock
 
 import pytest
 from click.testing import CliRunner
@@ -109,18 +110,34 @@ temperature = 0.7
         except json.JSONDecodeError:
             pytest.fail(f"Output is not valid JSON: {result.output}")
 
-    def test_config_show_toml_displays_raw_content(self, tmp_path: Path) -> None:
-        """Test that config show toml displays the raw TOML content."""
+    @pytest.mark.parametrize("output_format", ["toml", "json"])
+    def test_config_show_uses_utf8_for_config_file(
+        self, tmp_path: Path, output_format: str
+    ) -> None:
+        """Test that config show reads UTF-8 config files explicitly."""
         # Create a temporary config file
         config_file = tmp_path / "test_config.toml"
-        config_file.write_text('[engine]\ndefault = "ollama"\n')
-
-        result = CliRunner().invoke(
-            cli, ["config", "show", "toml", "--path", str(config_file)]
+        config_file.write_text(
+            '# Preset comment — stored as UTF-8\n[engine]\ndefault = "ollama"\n',
+            encoding="utf-8",
         )
+        original_read_text = Path.read_text
+
+        def read_text(path: Path, *args: object, **kwargs: object) -> str:
+            if path == config_file:
+                assert kwargs.get("encoding") == "utf-8"
+            return original_read_text(path, *args, **kwargs)
+
+        with mock.patch.object(Path, "read_text", autospec=True, side_effect=read_text):
+            result = CliRunner().invoke(
+                cli, ["config", "show", output_format, "--path", str(config_file)]
+            )
 
         assert result.exit_code == 0
-        assert "[engine]" in result.output
+        if output_format == "toml":
+            assert "[engine]" in result.output
+        else:
+            assert '"engine"' in result.output
         assert "ollama" in result.output
 
     def test_config_show_json_displays_parsed_content(self, tmp_path: Path) -> None:

tests/cli/test_config_set.py

@@ -60,6 +60,42 @@ class TestConfigSet:
         assert "vllm" in content
         assert "qwen2.5:3b" in content
 
+    def test_set_uses_utf8_for_existing_config(self, tmp_path: Path) -> None:
+        """config set preserves a UTF-8 config regardless of the system locale."""
+        config_file = tmp_path / "config.toml"
+        config_file.write_text(
+            '# Preset comment — stored as UTF-8\n[engine]\ndefault = "ollama"\n',
+            encoding="utf-8",
+        )
+        original_read_text = Path.read_text
+        original_write_text = Path.write_text
+
+        def read_text(path: Path, *args: object, **kwargs: object) -> str:
+            if path == config_file:
+                assert kwargs.get("encoding") == "utf-8"
+            return original_read_text(path, *args, **kwargs)
+
+        def write_text(path: Path, data: str, *args: object, **kwargs: object) -> int:
+            if path == config_file:
+                assert kwargs.get("encoding") == "utf-8"
+            return original_write_text(path, data, *args, **kwargs)
+
+        with (
+            mock.patch.dict(os.environ, {"OPENJARVIS_CONFIG": str(config_file)}),
+            mock.patch.object(Path, "read_text", autospec=True, side_effect=read_text),
+            mock.patch.object(
+                Path, "write_text", autospec=True, side_effect=write_text
+            ),
+        ):
+            result = CliRunner().invoke(
+                cli, ["config", "set", "engine.default", "vllm"]
+            )
+
+        assert result.exit_code == 0
+        content = config_file.read_text(encoding="utf-8")
+        assert "Preset comment — stored as UTF-8" in content
+        assert "vllm" in content
+
     def test_set_invalid_key_rejected(self, tmp_path: Path) -> None:
         """config set rejects unknown keys."""
         config_file = tmp_path / "config.toml"

tests/engine/test_cloud_stream_full.py

@@ -3,6 +3,8 @@ and _prepare_anthropic_messages."""
 
 from __future__ import annotations
 
+import sys
+from types import ModuleType, SimpleNamespace
 from typing import Any, List
 from unittest.mock import MagicMock
 
@@ -63,6 +65,36 @@ def _openai_tool_call_delta(
     return tc
 
 
+class _GoogleConfig:
+    def __init__(self, **kwargs: Any) -> None:
+        self.__dict__.update(kwargs)
+
+
+def _google_stream_chunk(
+    *parts: Any,
+    text: str | None = None,
+    usage_metadata: Any = None,
+) -> Any:
+    candidates = []
+    if parts:
+        candidates = [SimpleNamespace(content=SimpleNamespace(parts=list(parts)))]
+    return SimpleNamespace(
+        text=text,
+        candidates=candidates,
+        usage_metadata=usage_metadata,
+    )
+
+
+def _google_types_modules() -> dict[str, ModuleType]:
+    types = ModuleType("google.genai.types")
+    types.GenerateContentConfig = _GoogleConfig
+    genai = ModuleType("google.genai")
+    genai.types = types
+    google = ModuleType("google")
+    google.genai = genai
+    return {"google": google, "google.genai": genai, "google.genai.types": types}
+
+
 # ---------------------------------------------------------------------------
 # _stream_full_openai tests
 # ---------------------------------------------------------------------------
@@ -413,6 +445,316 @@ def test_prepare_anthropic_messages_tool_calls():
     assert blocks[1]["input"] == {"city": "Berlin"}
 
 
+# ---------------------------------------------------------------------------
+# _stream_full_google tests
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_stream_full_google_text_only(monkeypatch: pytest.MonkeyPatch):
+    """Google text chunks retain their content and finish normally."""
+    client = MagicMock()
+    client.models.generate_content_stream.return_value = iter(
+        [_google_stream_chunk(text="Hello"), _google_stream_chunk(text=" world")]
+    )
+    engine = _make_cloud_engine(google_client=client)
+    engine._thought_sigs = {}
+    messages = [Message(role=Role.USER, content="hi")]
+    modules = _google_types_modules()
+
+    with monkeypatch.context() as patch:
+        for name, module in modules.items():
+            patch.setitem(sys.modules, name, module)
+        result = [
+            chunk
+            async for chunk in engine.stream_full(messages, model="gemini-2.5-flash")
+        ]
+
+    assert [chunk.content for chunk in result[:-1]] == ["Hello", " world"]
+    assert result[-1].finish_reason == "stop"
+
+
+@pytest.mark.asyncio
+async def test_stream_full_google_preserves_tool_calls(monkeypatch: pytest.MonkeyPatch):
+    """Google function_call parts become OpenAI-compatible tool call chunks."""
+    function_call = SimpleNamespace(name="get_weather", args={"city": "Berlin"})
+    part = SimpleNamespace(
+        function_call=function_call, text=None, thought_signature=b"sig"
+    )
+    client = MagicMock()
+    client.models.generate_content_stream.return_value = iter(
+        [_google_stream_chunk(part)]
+    )
+    engine = _make_cloud_engine(google_client=client)
+    engine._thought_sigs = {}
+    messages = [Message(role=Role.USER, content="weather")]
+    modules = _google_types_modules()
+
+    with monkeypatch.context() as patch:
+        for name, module in modules.items():
+            patch.setitem(sys.modules, name, module)
+        result = [
+            chunk
+            async for chunk in engine.stream_full(
+                messages,
+                model="gemini-2.5-flash",
+                tools=[
+                    {
+                        "type": "function",
+                        "function": {
+                            "name": "get_weather",
+                            "description": "Get weather",
+                            "parameters": {"type": "object", "properties": {}},
+                        },
+                    }
+                ],
+            )
+        ]
+
+    tool_call = result[0].tool_calls[0]
+    assert tool_call["index"] == 0
+    assert tool_call["id"].startswith("google_")
+    assert tool_call["type"] == "function"
+    assert tool_call["function"] == {
+        "name": "get_weather",
+        "arguments": '{"city": "Berlin"}',
+    }
+    assert tool_call["thought_signature"] == b"sig"
+    assert engine._thought_sigs[tool_call["id"]] == b"sig"
+    assert result[-1].finish_reason == "tool_calls"
+    config = client.models.generate_content_stream.call_args.kwargs["config"]
+    assert config.tools == [
+        {
+            "function_declarations": [
+                {
+                    "name": "get_weather",
+                    "description": "Get weather",
+                    "parameters": {"type": "object", "properties": {}},
+                }
+            ]
+        }
+    ]
+
+
+@pytest.mark.asyncio
+async def test_stream_full_google_preserves_mixed_and_multiple_calls(
+    monkeypatch: pytest.MonkeyPatch,
+):
+    """Google streams retain mixed text and multiple tool calls."""
+    weather = SimpleNamespace(name="get_weather", args={"city": "Berlin"})
+    calendar = SimpleNamespace(name="get_calendar", args={"day": "Monday"})
+    text_part = SimpleNamespace(text="I'll check.", function_call=None)
+    weather_part = SimpleNamespace(
+        function_call=weather, text=None, thought_signature=None
+    )
+    calendar_part = SimpleNamespace(
+        function_call=calendar, text=None, thought_signature=None
+    )
+    client = MagicMock()
+    client.models.generate_content_stream.return_value = iter(
+        [
+            _google_stream_chunk(text_part, weather_part),
+            _google_stream_chunk(calendar_part),
+        ]
+    )
+    engine = _make_cloud_engine(google_client=client)
+    engine._thought_sigs = {}
+    modules = _google_types_modules()
+
+    with monkeypatch.context() as patch:
+        for name, module in modules.items():
+            patch.setitem(sys.modules, name, module)
+        result = [
+            chunk
+            async for chunk in engine.stream_full(
+                [Message(role=Role.USER, content="plan")], model="gemini-2.5-flash"
+            )
+        ]
+
+    assert result[0].content == "I'll check."
+    weather_call = result[1].tool_calls[0]
+    calendar_call = result[2].tool_calls[0]
+    assert weather_call["index"] == 0
+    assert weather_call["function"] == {
+        "name": "get_weather",
+        "arguments": '{"city": "Berlin"}',
+    }
+    assert calendar_call["index"] == 1
+    assert calendar_call["function"] == {
+        "name": "get_calendar",
+        "arguments": '{"day": "Monday"}',
+    }
+    assert weather_call["id"] != calendar_call["id"]
+    assert result[-1].finish_reason == "tool_calls"
+
+
+@pytest.mark.asyncio
+async def test_stream_full_google_keeps_parallel_same_name_calls_distinct(
+    monkeypatch: pytest.MonkeyPatch,
+):
+    """Parallel invocations of one function receive unique indexes and IDs."""
+    paris = SimpleNamespace(name="get_weather", args={"city": "Paris"})
+    london = SimpleNamespace(name="get_weather", args={"city": "London"})
+    parts = [
+        SimpleNamespace(function_call=paris, text=None, thought_signature=b"sig"),
+        SimpleNamespace(function_call=london, text=None, thought_signature=None),
+    ]
+    client = MagicMock()
+    client.models.generate_content_stream.return_value = iter(
+        [_google_stream_chunk(*parts)]
+    )
+    engine = _make_cloud_engine(google_client=client)
+    engine._thought_sigs = {}
+
+    with monkeypatch.context() as patch:
+        for name, module in _google_types_modules().items():
+            patch.setitem(sys.modules, name, module)
+        result = [
+            chunk
+            async for chunk in engine.stream_full(
+                [Message(role=Role.USER, content="Weather in Paris and London")],
+                model="gemini-3-flash-preview",
+            )
+        ]
+
+    calls = result[0].tool_calls
+    assert [call["index"] for call in calls] == [0, 1]
+    assert calls[0]["id"] != calls[1]["id"]
+    assert [call["function"]["arguments"] for call in calls] == [
+        '{"city": "Paris"}',
+        '{"city": "London"}',
+    ]
+
+
+@pytest.mark.asyncio
+async def test_stream_full_google_ids_are_unique_across_requests(
+    monkeypatch: pytest.MonkeyPatch,
+):
+    """Shared engines keep signatures isolated between conversations."""
+    first_part = SimpleNamespace(
+        function_call=SimpleNamespace(name="get_weather", args={"city": "Paris"}),
+        text=None,
+        thought_signature=b"paris-sig",
+    )
+    second_part = SimpleNamespace(
+        function_call=SimpleNamespace(name="get_weather", args={"city": "London"}),
+        text=None,
+        thought_signature=b"london-sig",
+    )
+    client = MagicMock()
+    client.models.generate_content_stream.side_effect = [
+        iter([_google_stream_chunk(first_part)]),
+        iter([_google_stream_chunk(second_part)]),
+    ]
+    engine = _make_cloud_engine(google_client=client)
+    engine._thought_sigs = {}
+
+    with monkeypatch.context() as patch:
+        for name, module in _google_types_modules().items():
+            patch.setitem(sys.modules, name, module)
+        first = [
+            chunk
+            async for chunk in engine.stream_full(
+                [Message(role=Role.USER, content="Weather in Paris")],
+                model="gemini-3-flash-preview",
+            )
+        ]
+        second = [
+            chunk
+            async for chunk in engine.stream_full(
+                [Message(role=Role.USER, content="Weather in London")],
+                model="gemini-3-flash-preview",
+            )
+        ]
+
+    first_id = first[0].tool_calls[0]["id"]
+    second_id = second[0].tool_calls[0]["id"]
+    assert first_id != second_id
+    assert engine._thought_sigs[first_id] == b"paris-sig"
+    assert engine._thought_sigs[second_id] == b"london-sig"
+
+
+@pytest.mark.asyncio
+async def test_stream_full_google_emits_final_usage(monkeypatch: pytest.MonkeyPatch):
+    """Google's final usage metadata is normalized onto the terminal chunk."""
+    usage = SimpleNamespace(prompt_token_count=12, candidates_token_count=5)
+    client = MagicMock()
+    client.models.generate_content_stream.return_value = iter(
+        [
+            _google_stream_chunk(text="Hello"),
+            _google_stream_chunk(usage_metadata=usage),
+        ]
+    )
+    engine = _make_cloud_engine(google_client=client)
+    engine._thought_sigs = {}
+
+    with monkeypatch.context() as patch:
+        for name, module in _google_types_modules().items():
+            patch.setitem(sys.modules, name, module)
+        result = [
+            chunk
+            async for chunk in engine.stream_full(
+                [Message(role=Role.USER, content="hi")],
+                model="gemini-2.5-flash",
+            )
+        ]
+
+    assert result[-1].finish_reason == "stop"
+    assert result[-1].usage == {
+        "prompt_tokens": 12,
+        "completion_tokens": 5,
+        "total_tokens": 17,
+    }
+
+
+@pytest.mark.asyncio
+async def test_stream_full_google_replays_signature_on_part(
+    monkeypatch: pytest.MonkeyPatch,
+):
+    """A saved Gemini signature is replayed beside, not inside, function_call."""
+    client = MagicMock()
+    client.models.generate_content_stream.return_value = iter([])
+    engine = _make_cloud_engine(google_client=client)
+    engine._thought_sigs = {"google_get_weather_0": b"sig"}
+    messages = [
+        Message(role=Role.USER, content="weather"),
+        Message(
+            role=Role.ASSISTANT,
+            content=None,
+            tool_calls=[
+                ToolCall(
+                    id="google_get_weather_0",
+                    name="get_weather",
+                    arguments='{"city": "Berlin"}',
+                )
+            ],
+        ),
+        Message(role=Role.TOOL, name="get_weather", content='{"temp": 20}'),
+    ]
+
+    with monkeypatch.context() as patch:
+        for name, module in _google_types_modules().items():
+            patch.setitem(sys.modules, name, module)
+        result = [
+            chunk
+            async for chunk in engine.stream_full(
+                messages, model="gemini-3-flash-preview"
+            )
+        ]
+
+    contents = client.models.generate_content_stream.call_args.kwargs["contents"]
+    assert contents[1]["parts"] == [
+        {
+            "function_call": {
+                "name": "get_weather",
+                "args": {"city": "Berlin"},
+            },
+            "thought_signature": b"sig",
+        }
+    ]
+    assert result[-1].finish_reason == "stop"
+
+
 # ---------------------------------------------------------------------------
 # stream_full routing tests
 # ---------------------------------------------------------------------------