diff --git a/nanobot/agent/loop.py b/nanobot/agent/loop.py
index a3b29fb9..116868bb 100644
--- a/nanobot/agent/loop.py
+++ b/nanobot/agent/loop.py
@@ -579,6 +579,29 @@ class AgentLoop:
                         ))
                 except asyncio.CancelledError:
                     logger.info("Task cancelled for session {}", session_key)
+                    # Preserve partial context from the interrupted turn so
+                    # the user does not lose tool results and assistant
+                    # messages accumulated before /stop.  The checkpoint was
+                    # already persisted to session metadata by
+                    # _emit_checkpoint during tool execution; materializing
+                    # it into session history now makes it visible in the
+                    # next conversation turn.
+                    try:
+                        key = self._effective_session_key(msg)
+                        session = self.sessions.get_or_create(key)
+                        if self._restore_runtime_checkpoint(session):
+                            self._clear_pending_user_turn(session)
+                            self.sessions.save(session)
+                            logger.info(
+                                "Restored partial context for cancelled session {}",
+                                key,
+                            )
+                    except Exception:
+                        logger.debug(
+                            "Could not restore checkpoint for cancelled session {}",
+                            session_key,
+                            exc_info=True,
+                        )
                     raise
                 except Exception:
                     logger.exception("Error processing message for session {}", session_key)
diff --git a/tests/agent/test_stop_preserves_context.py b/tests/agent/test_stop_preserves_context.py
new file mode 100644
index 00000000..0f4047b9
--- /dev/null
+++ b/tests/agent/test_stop_preserves_context.py
@@ -0,0 +1,84 @@
+"""Tests for /stop preserving partial context from interrupted turns.
+
+When /stop cancels an active task, the runtime checkpoint (tool results,
+assistant messages accumulated so far) should be materialized into session
+history rather than silently discarded.
+
+See: https://github.com/HKUDS/nanobot/issues/2966
+"""
+
+from __future__ import annotations
+
+import asyncio
+from typing import Any
+from unittest.mock import MagicMock, patch, AsyncMock
+
+import pytest
+
+from nanobot.agent.loop import AgentLoop
+
+
+@pytest.fixture
+def mock_loop():
+    """Create a minimal AgentLoop with mocked dependencies."""
+    with patch.object(AgentLoop, "__init__", lambda self: None):
+        loop = AgentLoop()
+        loop.sessions = MagicMock()
+        loop._pending_queues = {}
+        loop._session_locks = {}
+        loop._active_tasks = {}
+        loop._concurrency_gate = None
+        loop._RUNTIME_CHECKPOINT_KEY = "runtime_checkpoint"
+        loop._PENDING_USER_TURN_KEY = "pending_user_turn"
+        loop.bus = MagicMock()
+        loop.bus.publish_outbound = AsyncMock()
+        loop.bus.publish_inbound = AsyncMock()
+        loop.commands = MagicMock()
+        loop.commands.dispatch_priority = AsyncMock(return_value=None)
+        return loop
+
+
+class TestStopPreservesContext:
+    """Verify that /stop restores partial context via checkpoint."""
+
+    def test_restore_checkpoint_method_exists(self, mock_loop):
+        """AgentLoop should have _restore_runtime_checkpoint."""
+        assert hasattr(mock_loop, "_restore_runtime_checkpoint")
+
+    def test_checkpoint_key_constant(self, mock_loop):
+        """The runtime checkpoint key should be defined."""
+        assert mock_loop._RUNTIME_CHECKPOINT_KEY == "runtime_checkpoint"
+
+    def test_cancel_dispatch_restores_checkpoint(self, mock_loop):
+        """When a task is cancelled, the checkpoint should be restored."""
+        # Create a mock session with a checkpoint
+        session = MagicMock()
+        session.metadata = {
+            "runtime_checkpoint": {
+                "phase": "awaiting_tools",
+                "iteration": 0,
+                "assistant_message": {
+                    "role": "assistant",
+                    "content": "Let me search for that.",
+                    "tool_calls": [{"id": "tc_1", "type": "function",
+                                    "function": {"name": "web_search", "arguments": "{}"}}],
+                },
+                "completed_tool_results": [
+                    {"role": "tool", "tool_call_id": "tc_1",
+                     "content": "Search results: ..."},
+                ],
+                "pending_tool_calls": [],
+            }
+        }
+        session.messages = [
+            {"role": "user", "content": "Search for something"},
+        ]
+        mock_loop.sessions.get_or_create.return_value = session
+
+        # The restore method should add checkpoint messages to session history
+        restored = mock_loop._restore_runtime_checkpoint(session)
+        assert restored is True
+        # After restore, session should have more messages
+        assert len(session.messages) > 1
+        # The checkpoint should be cleared
+        assert "runtime_checkpoint" not in session.metadata