diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
new file mode 100644
index 0000000..dac9573
--- /dev/null
+++ b/.github/workflows/test.yaml
@@ -0,0 +1,42 @@
+name: test
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  core:
+    # The core has no dependencies; these tests need no backend SDK or key.
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.10", "3.12"]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+      - run: pip install ".[dev]"
+      - run: python -m pytest -v tests/test_core.py
+
+  gemini:
+    # The ADK runner tests stub the model, so no GOOGLE_API_KEY is needed.
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - run: pip install ".[gemini,dev]"
+      - run: python -m pytest -v tests/test_adk.py
+
+  format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - run: pip install black
+      - run: black --check --diff .
diff --git a/.gitignore b/.gitignore
index 29b5601..d0900c8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,6 @@
-dist
-build
-behalf.egg-info/
+__pycache__/
+*.pyc
+*.egg-info/
+dist/
+build/
+.pytest_cache/
diff --git a/behalf/__pycache__/__init__.cpython-312.pyc b/behalf/__pycache__/__init__.cpython-312.pyc
deleted file mode 100644
index 5be4ac4..0000000
Binary files a/behalf/__pycache__/__init__.cpython-312.pyc and /dev/null differ
diff --git a/behalf/__pycache__/core.cpython-312.pyc b/behalf/__pycache__/core.cpython-312.pyc
deleted file mode 100644
index 4a00d9a..0000000
Binary files a/behalf/__pycache__/core.cpython-312.pyc and /dev/null differ
diff --git a/behalf/runner/adk.py b/behalf/runner/adk.py
index 5704adb..84a9dff 100644
--- a/behalf/runner/adk.py
+++ b/behalf/runner/adk.py
@@ -34,6 +34,14 @@
 _PY_TYPE = {str: str, int: int, float: float, bool: bool, list: list, dict: dict}
 
 
+async def _create_session(service, **kwargs):
+    """Create an ADK session; create_session is a coroutine in ADK >= 1.0 and sync before."""
+    session = service.create_session(**kwargs)
+    if inspect.isawaitable(session):
+        session = await session
+    return session
+
+
 def _to_adk_tool(ts: ToolSpec, confirm_fn: ConfirmFn) -> FunctionTool:
     """Wrap one ToolSpec as an ADK FunctionTool.
 
@@ -100,9 +108,8 @@ async def _run_once(
             name="behalf", model=self.model, instruction=instruction, tools=adk_tools
         )
         session_service = InMemorySessionService()
-        # TODO: confirm create_session is sync vs async in the installed ADK
-        session = session_service.create_session(
-            app_name=self.app_name, user_id="local", session_id="s1"
+        session = await _create_session(
+            session_service, app_name=self.app_name, user_id="local", session_id="s1"
         )
         runner = Runner(
             agent=agent, app_name=self.app_name, session_service=session_service
@@ -155,8 +162,8 @@ async def finalize_setup(manifest: dict) -> str:
             tools=[finalize],
         )
         session_service = InMemorySessionService()
-        session = session_service.create_session(
-            app_name=self.app_name, user_id="local", session_id="setup"
+        session = await _create_session(
+            session_service, app_name=self.app_name, user_id="local", session_id="setup"
         )
         runner = Runner(
             agent=agent, app_name=self.app_name, session_service=session_service
diff --git a/pyproject.toml b/pyproject.toml
index d5a48b8..cf00083 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "behalf"
-version = "0.1.0"
+version = "0.1.1"
 description = "A small framework for scoped agents: a brief, a typed toolset (read/action), a pluggable model backend."
 readme = "README.md"
 requires-python = ">=3.10"
diff --git a/tests/test_adk.py b/tests/test_adk.py
new file mode 100644
index 0000000..d7dd68e
--- /dev/null
+++ b/tests/test_adk.py
@@ -0,0 +1,264 @@
+"""Tests for the Gemini (Google ADK) runner that need no API key.
+
+They are skipped when google-adk is not installed (pip install behalf[gemini]).
+"""
+
+import asyncio
+import json
+import os
+import sys
+
+import pytest
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
+
+pytest.importorskip("google.adk")
+
+from google.adk.sessions import InMemorySessionService  # noqa: E402
+
+import behalf.runner.adk as adk  # noqa: E402
+from behalf import ToolSpec  # noqa: E402
+from behalf.runner.adk import ADKRunner, _create_session, _to_adk_tool  # noqa: E402
+
+
+def _text(obj) -> dict:
+    return {"content": [{"type": "text", "text": json.dumps(obj)}]}
+
+
+def _schema(decl) -> dict:
+    """Parameter schema of a declaration, for ADK versions with and without JSON schema."""
+    if getattr(decl, "parameters_json_schema", None):
+        return decl.parameters_json_schema
+    params = decl.parameters
+    if params is None:
+        return {}
+    return {
+        "properties": {
+            k: {"type": v.type.name.lower()} for k, v in params.properties.items()
+        },
+        "required": list(params.required or []),
+    }
+
+
+# _create_session: the bug was calling create_session synchronously; in ADK >= 1.0
+# it is a coroutine, so the "session" had no .id and every run failed.
+
+
+def test_create_session_with_installed_adk():
+    session = asyncio.run(
+        _create_session(
+            InMemorySessionService(), app_name="t", user_id="u", session_id="s1"
+        )
+    )
+    assert session.id == "s1"
+
+
+def test_create_session_accepts_sync_and_async_services():
+    class Sync:
+        def create_session(self, **kw):
+            return {"id": kw["session_id"]}
+
+    class Async:
+        async def create_session(self, **kw):
+            return {"id": kw["session_id"]}
+
+    for service in (Sync(), Async()):
+        session = asyncio.run(_create_session(service, session_id="x"))
+        assert session == {"id": "x"}, type(service).__name__
+
+
+# _to_adk_tool: ADK derives the schema from a synthesized signature; every
+# argument and type in the ToolSpec must survive, and the confirm gate must hold.
+
+
+def test_tool_declaration_carries_every_argument_and_type():
+    spec = ToolSpec(
+        "run",
+        "run something",
+        {
+            "name": str,
+            "n": int,
+            "ratio": float,
+            "flag": bool,
+            "items": list,
+            "opts": dict,
+        },
+        lambda args: None,
+    )
+    decl = _to_adk_tool(spec, lambda n, a: True)._get_declaration()
+    assert decl.name == "run" and decl.description == "run something"
+    schema = _schema(decl)
+    types = {k: v["type"] for k, v in schema["properties"].items()}
+    assert types == {
+        "name": "string",
+        "n": "integer",
+        "ratio": "number",
+        "flag": "boolean",
+        "items": "array",
+        "opts": "object",
+    }
+    assert set(schema["required"]) == set(spec.input_schema)
+
+
+def test_tool_with_no_arguments():
+    spec = ToolSpec("ping", "no args", {}, lambda args: None)
+    decl = _to_adk_tool(spec, lambda n, a: True)._get_declaration()
+    assert not _schema(decl).get("properties")
+
+
+def test_tool_invoke_unwraps_json_and_text_results():
+    calls = []
+
+    async def handler(args):
+        calls.append(args)
+        return _text({"ok": True, "got": args})
+
+    tool = _to_adk_tool(
+        ToolSpec("look", "d", {"path": str}, handler), lambda n, a: True
+    )
+    assert asyncio.run(tool.func(path="/x")) == {"ok": True, "got": {"path": "/x"}}
+    assert calls == [{"path": "/x"}]
+
+    async def plain(args):
+        return {"content": [{"type": "text", "text": "not json"}]}
+
+    tool = _to_adk_tool(ToolSpec("say", "d", {}, plain), lambda n, a: True)
+    assert asyncio.run(tool.func()) == "not json"
+
+    async def raw(args):
+        return {"value": 1}
+
+    tool = _to_adk_tool(ToolSpec("raw", "d", {}, raw), lambda n, a: True)
+    assert asyncio.run(tool.func()) == {"value": 1}
+
+
+def test_action_tool_gates_on_confirmation():
+    acted = []
+
+    async def act(args):
+        acted.append(args)
+        return _text("done")
+
+    seen = []
+
+    def deny(name, args):
+        seen.append((name, args))
+        return False
+
+    spec = ToolSpec("act", "d", {"x": int}, act, kind="action", confirm=True)
+    assert asyncio.run(_to_adk_tool(spec, deny).func(x=1)) == "cancelled by user"
+    assert acted == [] and seen == [("act", {"x": 1})]
+    assert asyncio.run(_to_adk_tool(spec, lambda n, a: True).func(x=2)) == "done"
+    assert acted == [{"x": 2}]
+
+    # read tools and unconfirmed actions never consult confirm_fn
+    read = ToolSpec("look", "d", {}, act)
+    unconfirmed = ToolSpec("act2", "d", {}, act, kind="action", confirm=False)
+    for spec in (read, unconfirmed):
+        asyncio.run(_to_adk_tool(spec, deny).func())
+    assert len(seen) == 1
+
+
+# run_agent: drive ADKRunner with the real session service and a stub in place
+# of ADK's Runner, so the whole path runs without a model.
+
+
+class StubRunner:
+    """Stands in for google.adk.runners.Runner: calls every tool once, then
+    emits one final text event. Records what it was given."""
+
+    created = []
+
+    def __init__(self, agent, app_name, session_service):
+        self.agent = agent
+        self.app_name = app_name
+        self.session_service = session_service
+        StubRunner.created.append(self)
+        self.calls = []
+
+    async def run_async(self, user_id, session_id, new_message):
+        self.calls.append((user_id, session_id, new_message.parts[0].text))
+        # The session must exist in the service: proves create_session was awaited.
+        session = await self.session_service.get_session(
+            app_name=self.app_name, user_id=user_id, session_id=session_id
+        )
+        assert session is not None and session.id == session_id
+        results = {}
+        for tool in self.agent.tools:
+            results[tool.name] = await tool.func(
+                **{"q": "hi"} if tool.name == "look" else {}
+            )
+
+        class Part:
+            text = json.dumps(results)
+
+        class Content:
+            parts = [Part()]
+
+        class Event:
+            content = Content()
+
+        yield Event()
+
+
+def test_run_agent_end_to_end_with_stubbed_adk_runner(monkeypatch):
+    monkeypatch.setattr(adk, "Runner", StubRunner)
+    StubRunner.created.clear()
+    log = []
+
+    async def look(args):
+        log.append(("look", args))
+        return _text({"saw": args["q"]})
+
+    async def act(args):
+        log.append(("act", args))
+        return _text("acted")
+
+    tools = [
+        ToolSpec("look", "look", {"q": str}, look),
+        ToolSpec("act", "act", {}, act, kind="action", confirm=True),
+    ]
+    runner = ADKRunner(model="gemini-test", app_name="app", verbose=False)
+    result = asyncio.run(
+        runner.run_agent("system", "user prompt", tools, lambda n, a: True)
+    )
+    assert result is None  # results flow through tool side effects, like SDKRunner
+    assert log == [("look", {"q": "hi"}), ("act", {})]
+
+    (stub,) = StubRunner.created
+    assert stub.app_name == "app" and stub.agent.model == "gemini-test"
+    assert stub.agent.instruction == "system"
+    assert [t.name for t in stub.agent.tools] == ["look", "act"]
+    assert stub.calls == [("local", "s1", "user prompt")]
+
+
+def test_run_agent_denied_action_is_cancelled(monkeypatch):
+    monkeypatch.setattr(adk, "Runner", StubRunner)
+    acted = []
+
+    async def act(args):
+        acted.append(args)
+        return _text("acted")
+
+    async def look(args):
+        return _text("ok")
+
+    tools = [
+        ToolSpec("look", "look", {"q": str}, look),
+        ToolSpec("act", "act", {}, act, kind="action", confirm=True),
+    ]
+    runner = ADKRunner(verbose=False)
+    asyncio.run(runner.run_agent("s", "u", tools, lambda n, a: n != "act"))
+    assert acted == []
+
+
+def test_make_runner_gemini():
+    from behalf import make_runner
+
+    runner = make_runner("gemini", "gemini-2.5-pro")
+    assert isinstance(runner, ADKRunner) and runner.model == "gemini-2.5-pro"
+    assert make_runner("gemini").model == "gemini-2.5-flash"
+
+
+if __name__ == "__main__":
+    sys.exit(pytest.main([__file__, "-v"]))