Add missing list_sessions() method to Python SDK client (#153)

* Initial plan

* Add list_sessions method to Python SDK client

Co-authored-by: friggeri <106686+friggeri@users.noreply.github.com>

* Improve type annotations for list_sessions method

Co-authored-by: friggeri <106686+friggeri@users.noreply.github.com>

* Add delete_session method to Python SDK client

Co-authored-by: friggeri <106686+friggeri@users.noreply.github.com>

* Use RuntimeError for consistent exception handling in delete_session

Co-authored-by: friggeri <106686+friggeri@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: friggeri <106686+friggeri@users.noreply.github.com>

Author: Copilot

python/copilot/__init__.py

@@ -28,6 +28,7 @@
     ResumeSessionConfig,
     SessionConfig,
     SessionEvent,
+    SessionMetadata,
     Tool,
     ToolHandler,
     ToolInvocation,
@@ -59,6 +60,7 @@
     "ResumeSessionConfig",
     "SessionConfig",
     "SessionEvent",
+    "SessionMetadata",
     "Tool",
     "ToolHandler",
     "ToolInvocation",

python/copilot/client.py

@@ -33,6 +33,7 @@
     ModelInfo,
     ResumeSessionConfig,
     SessionConfig,
+    SessionMetadata,
     ToolHandler,
     ToolInvocation,
     ToolResult,
@@ -633,6 +634,62 @@ async def list_models(self) -> List["ModelInfo"]:
         response = await self._client.request("models.list", {})
         return response.get("models", [])
 
+    async def list_sessions(self) -> List["SessionMetadata"]:
+        """
+        List all available sessions known to the server.
+
+        Returns metadata about each session including ID, timestamps, and summary.
+
+        Returns:
+            A list of session metadata dictionaries with keys: sessionId (str),
+            startTime (str), modifiedTime (str), summary (str, optional),
+            and isRemote (bool).
+
+        Raises:
+            RuntimeError: If the client is not connected.
+
+        Example:
+            >>> sessions = await client.list_sessions()
+            >>> for session in sessions:
+            ...     print(f"Session: {session['sessionId']}")
+        """
+        if not self._client:
+            raise RuntimeError("Client not connected")
+
+        response = await self._client.request("session.list", {})
+        return response.get("sessions", [])
+
+    async def delete_session(self, session_id: str) -> None:
+        """
+        Delete a session permanently.
+
+        This permanently removes the session and all its conversation history.
+        The session cannot be resumed after deletion.
+
+        Args:
+            session_id: The ID of the session to delete.
+
+        Raises:
+            RuntimeError: If the client is not connected or deletion fails.
+
+        Example:
+            >>> await client.delete_session("session-123")
+        """
+        if not self._client:
+            raise RuntimeError("Client not connected")
+
+        response = await self._client.request("session.delete", {"sessionId": session_id})
+
+        success = response.get("success", False)
+        if not success:
+            error = response.get("error", "Unknown error")
+            raise RuntimeError(f"Failed to delete session {session_id}: {error}")
+
+        # Remove from local sessions map if present
+        with self._sessions_lock:
+            if session_id in self._sessions:
+                del self._sessions[session_id]
+
     async def _verify_protocol_version(self) -> None:
         """Verify that the server's protocol version matches the SDK's expected version."""
         expected_version = get_sdk_protocol_version()

python/copilot/types.py

@@ -359,3 +359,13 @@ class GetModelsResponse(TypedDict):
     """Response from models.list"""
 
     models: List[ModelInfo]
+
+
+class SessionMetadata(TypedDict):
+    """Metadata about a session"""
+
+    sessionId: str  # Session identifier
+    startTime: str  # ISO 8601 timestamp when session was created
+    modifiedTime: str  # ISO 8601 timestamp when session was last modified
+    summary: NotRequired[str]  # Optional summary of the session
+    isRemote: bool  # Whether the session is remote

python/e2e/test_session.py

@@ -180,6 +180,53 @@ async def test_should_throw_error_resuming_nonexistent_session(self, ctx: E2ETes
         with pytest.raises(Exception):
             await ctx.client.resume_session("non-existent-session-id")
 
+    async def test_should_list_sessions(self, ctx: E2ETestContext):
+        # Create a couple of sessions
+        session1 = await ctx.client.create_session()
+        session2 = await ctx.client.create_session()
+
+        # List sessions and verify they're included
+        sessions = await ctx.client.list_sessions()
+        assert isinstance(sessions, list)
+
+        session_ids = [s["sessionId"] for s in sessions]
+        assert session1.session_id in session_ids
+        assert session2.session_id in session_ids
+
+        # Verify session metadata structure
+        for session_data in sessions:
+            assert "sessionId" in session_data
+            assert "startTime" in session_data
+            assert "modifiedTime" in session_data
+            assert "isRemote" in session_data
+            # summary is optional
+            assert isinstance(session_data["sessionId"], str)
+            assert isinstance(session_data["startTime"], str)
+            assert isinstance(session_data["modifiedTime"], str)
+            assert isinstance(session_data["isRemote"], bool)
+
+    async def test_should_delete_session(self, ctx: E2ETestContext):
+        # Create a session
+        session = await ctx.client.create_session()
+        session_id = session.session_id
+
+        # Verify session exists in the list
+        sessions = await ctx.client.list_sessions()
+        session_ids = [s["sessionId"] for s in sessions]
+        assert session_id in session_ids
+
+        # Delete the session
+        await ctx.client.delete_session(session_id)
+
+        # Verify session no longer exists in the list
+        sessions_after = await ctx.client.list_sessions()
+        session_ids_after = [s["sessionId"] for s in sessions_after]
+        assert session_id not in session_ids_after
+
+        # Verify we cannot resume the deleted session
+        with pytest.raises(Exception):
+            await ctx.client.resume_session(session_id)
+
     async def test_should_create_session_with_custom_tool(self, ctx: E2ETestContext):
         # This test uses the low-level Tool() API to show that Pydantic is optional
         def get_secret_number_handler(invocation):