diff --git a/backend/api/server.py b/backend/api/server.py
index 39fb5bf..124a47a 100644
--- a/backend/api/server.py
+++ b/backend/api/server.py
@@ -257,8 +257,7 @@ class RunManager:
 
     def cancel_latest(self, account_key: str, session_id: str) -> bool:
         with self._lock:
-            run_id = self._latest_by_session.get((account_key, session_id))
-            record = self._runs.get(run_id or '')
+            record = self._select_session_record(account_key, session_id)
         return self.cancel_record(record)
 
     def cancel_run(self, run_id: str) -> bool:
@@ -782,7 +781,20 @@ def create_app(state: AgentState) -> FastAPI:
             state._account_key(account_id),
             safe_id,
         )
-        return snapshot or {'session_id': safe_id, 'status': 'idle'}
+        if snapshot is not None:
+            return snapshot
+        directory = state.account_paths(account_id)['sessions']
+        try:
+            stored = load_agent_session(safe_id, directory=directory)
+        except FileNotFoundError:
+            return {'session_id': safe_id, 'status': 'idle'}
+        if _stored_session_has_incomplete_tail(stored):
+            return {
+                'session_id': safe_id,
+                'status': 'interrupted',
+                'current_stage': '上次运行已中断，后台没有正在执行的进程',
+            }
+        return {'session_id': safe_id, 'status': 'idle'}
 
     @app.post('/api/runs/cancel')
     async def cancel_run(payload: RunCancelRequest) -> dict[str, Any]:
@@ -797,6 +809,12 @@ def create_app(state: AgentState) -> FastAPI:
                 safe_id,
             )
         )
+        if cancelled:
+            _mark_session_interrupted(
+                state.account_paths(payload.account_id)['sessions'],
+                safe_id,
+                status='cancelled',
+            )
         return {'session_id': safe_id, 'cancelled': cancelled}
 
     def _run_chat_payload(
@@ -875,6 +893,7 @@ def create_app(state: AgentState) -> FastAPI:
                                 status_code=404,
                                 detail='Session to resume not found',
                             )
+                        stored = _sanitize_stored_session_for_resume(stored)
                         result = agent.resume(
                             request.prompt.strip(),
                             stored,
@@ -889,9 +908,23 @@ def create_app(state: AgentState) -> FastAPI:
                             event_sink=event_sink,
                         )
                 except Exception as exc:
+                    _mark_session_interrupted(
+                        session_directory,
+                        requested_session_id,
+                        status=(
+                            'cancelled'
+                            if run_record.cancel_event.is_set()
+                            else 'failed'
+                        ),
+                        detail=str(exc),
+                    )
                     state.run_manager.update(
                         run_record.run_id,
-                        status='failed',
+                        status=(
+                            'cancelled'
+                            if run_record.cancel_event.is_set()
+                            else 'failed'
+                        ),
                         error=str(exc),
                     )
                     raise
@@ -923,6 +956,12 @@ def create_app(state: AgentState) -> FastAPI:
                 run_record.run_id,
                 'cancelled' if run_record.cancel_event.is_set() else 'completed',
             )
+            if run_record.cancel_event.is_set() and result.session_id:
+                _mark_session_interrupted(
+                    session_directory,
+                    result.session_id,
+                    status='cancelled',
+                )
             return payload
 
     # ------------- chat ------------------------------------------------------
@@ -1048,6 +1087,9 @@ def _normalize_transcript_entry(entry: dict[str, Any]) -> dict[str, Any]:
     for key in ('name', 'tool_call_id', 'tool_calls', 'metadata', 'message_id'):
         if key in entry and entry[key] not in (None, '', [], {}):
             out[key] = entry[key]
+    for key in ('state', 'stop_reason'):
+        if key in entry and entry[key] not in (None, ''):
+            out[key] = entry[key]
     return out
 
 
@@ -1063,6 +1105,152 @@ def _serialize_stored_session(stored: StoredAgentSession) -> dict[str, Any]:
     }
 
 
+def _stored_session_has_incomplete_tail(stored: StoredAgentSession) -> bool:
+    _, changed = _trim_incomplete_message_tail(stored.messages)
+    if changed:
+        return True
+    budget_state = stored.budget_state if isinstance(stored.budget_state, dict) else {}
+    return budget_state.get('status') in {'queued', 'running'}
+
+
+def _mark_session_interrupted(
+    directory: Path,
+    session_id: str,
+    *,
+    status: str,
+    detail: str = '',
+) -> None:
+    try:
+        stored = load_agent_session(session_id, directory=directory)
+    except (FileNotFoundError, OSError, json.JSONDecodeError):
+        return
+    trimmed, changed = _trim_incomplete_message_tail(stored.messages)
+    budget_state = (
+        dict(stored.budget_state)
+        if isinstance(stored.budget_state, dict)
+        else {}
+    )
+    if not changed and budget_state.get('status') not in {'queued', 'running'}:
+        return
+    messages = list(trimmed)
+    if not _last_message_is_run_status(messages, status):
+        messages.append(
+            {
+                'role': 'assistant',
+                'content': _interrupted_session_message(status),
+                'state': 'final',
+                'stop_reason': status,
+                'metadata': {
+                    'kind': 'run_status',
+                    'status': status,
+                    'detail': detail[:500],
+                    'created_at_ms': int(time.time() * 1000),
+                },
+            }
+        )
+    budget_state['status'] = status
+    budget_state['interrupted_at'] = int(time.time())
+    save_agent_session(
+        replace(
+            stored,
+            messages=tuple(messages),
+            budget_state=budget_state,
+        ),
+        directory=directory,
+    )
+
+
+def _sanitize_stored_session_for_resume(
+    stored: StoredAgentSession,
+) -> StoredAgentSession:
+    trimmed, changed = _trim_incomplete_message_tail(stored.messages)
+    if not changed:
+        return stored
+    messages = list(trimmed)
+    if not _last_message_is_run_status(messages, 'interrupted'):
+        messages.append(
+            {
+                'role': 'assistant',
+                'content': _interrupted_session_message('interrupted'),
+                'state': 'final',
+                'stop_reason': 'interrupted',
+                'metadata': {
+                    'kind': 'run_status',
+                    'status': 'interrupted',
+                    'created_at_ms': int(time.time() * 1000),
+                },
+            }
+        )
+    budget_state = (
+        dict(stored.budget_state)
+        if isinstance(stored.budget_state, dict)
+        else {}
+    )
+    budget_state['status'] = 'interrupted'
+    return replace(
+        stored,
+        messages=tuple(messages),
+        budget_state=budget_state,
+    )
+
+
+def _trim_incomplete_message_tail(
+    messages: tuple[dict[str, Any], ...] | tuple[Any, ...],
+) -> tuple[tuple[dict[str, Any], ...], bool]:
+    trimmed = [dict(message) for message in messages if isinstance(message, dict)]
+    changed = False
+    while trimmed and _is_incomplete_session_message(trimmed[-1]):
+        trimmed.pop()
+        changed = True
+    while trimmed and _assistant_has_trailing_tool_call(trimmed[-1]):
+        trimmed.pop()
+        changed = True
+    return tuple(trimmed), changed
+
+
+def _is_incomplete_session_message(message: dict[str, Any]) -> bool:
+    state = message.get('state')
+    if isinstance(state, str) and state not in {'', 'final'}:
+        return True
+    metadata = message.get('metadata')
+    if isinstance(metadata, dict):
+        if (
+            message.get('role') != 'user'
+            and metadata.get('placeholder') is True
+            and metadata.get('status') == 'running'
+        ):
+            return True
+        if metadata.get('phase') in {'starting', 'running'} and message.get('role') == 'tool':
+            return True
+    return False
+
+
+def _assistant_has_trailing_tool_call(message: dict[str, Any]) -> bool:
+    if message.get('role') != 'assistant':
+        return False
+    tool_calls = message.get('tool_calls')
+    return isinstance(tool_calls, list) and bool(tool_calls)
+
+
+def _last_message_is_run_status(messages: list[dict[str, Any]], status: str) -> bool:
+    if not messages:
+        return False
+    metadata = messages[-1].get('metadata')
+    return (
+        isinstance(metadata, dict)
+        and metadata.get('kind') == 'run_status'
+        and metadata.get('status') == status
+    )
+
+
+def _interrupted_session_message(status: str) -> str:
+    if status == 'cancelled':
+        return '上一次任务已取消，后台没有正在执行的进程。你可以继续回复，或重新发起任务。'
+    if status == 'failed':
+        return '上一次任务异常中断，后台没有正在执行的进程。你可以继续回复，或重新发起任务。'
+    return '上一次任务已中断，后台没有正在执行的进程。你可以继续回复，或重新发起任务。'
+
+
 def _emit_runtime_event(
     event_sink: Any | None,
     event: dict[str, object],
diff --git a/frontend/app/components/assistant-ui/thread-list.tsx b/frontend/app/components/assistant-ui/thread-list.tsx
index 8e23a81..9beef27 100644
--- a/frontend/app/components/assistant-ui/thread-list.tsx
+++ b/frontend/app/components/assistant-ui/thread-list.tsx
@@ -35,8 +35,13 @@ type ClawStoredMessage = {
 	name?: string;
 	tool_call_id?: string;
 	tool_calls?: ClawStoredToolCall[];
+	state?: string;
+	stop_reason?: string;
 	metadata?: {
 		elapsed_ms?: unknown;
+		placeholder?: unknown;
+		phase?: unknown;
+		status?: unknown;
 	};
 };
 
@@ -48,11 +53,22 @@ type ClawStoredSession = {
 export type ClawRunStatus = {
 	run_id?: string;
 	session_id?: string;
-	status?: "idle" | "queued" | "running" | "completed" | "failed" | "cancelled";
+	status?:
+		| "idle"
+		| "queued"
+		| "running"
+		| "completed"
+		| "failed"
+		| "cancelled"
+		| "interrupted";
 	current_stage?: string;
 	started_at?: number;
 };
 
+type ClawActiveRunStatus = ClawRunStatus & {
+	status: "queued" | "running";
+};
+
 type ClawStoredToolCall = {
 	id?: string;
 	name?: string;
@@ -364,12 +380,12 @@ export function toReplayRepository(
 	runStatus?: ClawRunStatus | null,
 ): ExportedMessageRepository {
 	const messages: ExportedMessageRepository["messages"] = [];
-	const toolResults = collectToolResults(session.messages ?? []);
-	const lastAssistantContentIndex = findLastAssistantContentIndex(
-		session.messages ?? [],
-	);
+	const replayMessages = getReplayMessages(session.messages ?? [], runStatus);
+	const toolResults = collectToolResults(replayMessages);
+	const lastAssistantContentIndex =
+		findLastAssistantContentIndex(replayMessages);
 	let previousId: string | null = null;
-	for (const [index, message] of (session.messages ?? []).entries()) {
+	for (const [index, message] of replayMessages.entries()) {
 		if (message.role === "tool") continue;
 		if (message.role !== "user" && message.role !== "assistant") continue;
 		const content = cleanStoredContent(message.content ?? "");
@@ -421,6 +437,37 @@ export function toReplayRepository(
 		messages.push({ message: threadMessage, parentId: previousId });
 		previousId = id;
 	}
+	if (shouldShowInterruptedNotice(session.messages ?? [], runStatus)) {
+		const id = `${fallbackSessionId}-interrupted`;
+		const text =
+			runStatus?.status === "cancelled"
+				? "上一次任务已取消，后台没有正在执行的进程。你可以继续回复，或重新发起任务。"
+				: "上一次任务已中断，后台没有正在执行的进程。你可以继续回复，或重新发起任务。";
+		const parts = [{ type: "text", text }] as UIMessage["parts"];
+		const uiMessage: UIMessage = {
+			id,
+			role: "assistant",
+			parts,
+			metadata: { sessionId: session.session_id ?? fallbackSessionId },
+		} as UIMessage;
+		const threadMessage = {
+			id,
+			role: "assistant",
+			createdAt: new Date(),
+			content: toThreadMessageContent(parts),
+			status: { type: "complete", reason: "stop" },
+			metadata: {
+				unstable_state: null,
+				unstable_annotations: [],
+				unstable_data: [],
+				steps: [],
+				custom: { sessionId: session.session_id ?? fallbackSessionId },
+			},
+		} as ThreadMessage;
+		bindExternalStoreMessage(threadMessage, uiMessage);
+		messages.push({ message: threadMessage, parentId: previousId });
+		previousId = id;
+	}
 	if (isActiveRunStatus(runStatus)) {
 		const id = `${fallbackSessionId}-run-${runStatus.run_id ?? "active"}`;
 		const text =
@@ -468,10 +515,65 @@ export function toReplayRepository(
 
 function isActiveRunStatus(
 	runStatus?: ClawRunStatus | null,
-): runStatus is ClawRunStatus {
+): runStatus is ClawActiveRunStatus {
 	return runStatus?.status === "queued" || runStatus?.status === "running";
 }
 
+function getReplayMessages(
+	messages: readonly ClawStoredMessage[],
+	runStatus?: ClawRunStatus | null,
+) {
+	if (isActiveRunStatus(runStatus)) return [...messages];
+	return trimIncompleteReplayTail(messages);
+}
+
+function shouldShowInterruptedNotice(
+	messages: readonly ClawStoredMessage[],
+	runStatus?: ClawRunStatus | null,
+) {
+	if (isActiveRunStatus(runStatus)) return false;
+	return (
+		runStatus?.status === "interrupted" ||
+		runStatus?.status === "cancelled" ||
+		trimIncompleteReplayTail(messages).length !== messages.length
+	);
+}
+
+function trimIncompleteReplayTail(messages: readonly ClawStoredMessage[]) {
+	const trimmed = [...messages];
+	while (trimmed.length && isIncompleteReplayMessage(trimmed.at(-1))) {
+		trimmed.pop();
+	}
+	while (trimmed.length && hasTrailingAssistantToolCall(trimmed.at(-1))) {
+		trimmed.pop();
+	}
+	return trimmed;
+}
+
+function isIncompleteReplayMessage(message?: ClawStoredMessage) {
+	if (!message) return false;
+	if (message.state && message.state !== "final") return true;
+	if (
+		message.role === "tool" &&
+		(message.metadata?.phase === "starting" ||
+			message.metadata?.phase === "running")
+	) {
+		return true;
+	}
+	if (
+		message.role !== "user" &&
+		message.metadata?.placeholder === true &&
+		message.metadata?.status === "running"
+	) {
+		return true;
+	}
+	return false;
+}
+
+function hasTrailingAssistantToolCall(message?: ClawStoredMessage) {
+	return message?.role === "assistant" && Boolean(message.tool_calls?.length);
+}
+
 function normalizeRunTimestampMs(value: unknown) {
 	if (typeof value !== "number" || !Number.isFinite(value)) return undefined;
 	return value < 10_000_000_000 ? Math.round(value * 1000) : Math.round(value);
@@ -499,7 +601,11 @@ function cleanStoredContent(content: string) {
 function collectToolResults(messages: readonly ClawStoredMessage[]) {
 	const results = new Map<string, string>();
 	for (const message of messages) {
-		if (message.role === "tool" && message.tool_call_id) {
+		if (
+			message.role === "tool" &&
+			message.tool_call_id &&
+			!isIncompleteReplayMessage(message)
+		) {
 			results.set(message.tool_call_id, message.content ?? "");
 		}
 	}
diff --git a/tests/test_gui_server.py b/tests/test_gui_server.py
index c6ee70d..d685fbb 100644
--- a/tests/test_gui_server.py
+++ b/tests/test_gui_server.py
@@ -257,6 +257,109 @@ class GuiServerTests(unittest.TestCase):
             self.assertEqual(payload['status'], 'running')
             self.assertEqual(payload['current_stage'], 'first stage')
 
+    def test_cancel_run_marks_streaming_session_tail_cancelled(self) -> None:
+        with tempfile.TemporaryDirectory() as d:
+            root = Path(d)
+            client, state = _build_client(root)
+            session_root = root / 'accounts' / 'alice' / 'sessions'
+            save_agent_session(
+                StoredAgentSession(
+                    session_id='thread-1',
+                    model_config={'model': 'test-model'},
+                    runtime_config={'cwd': str(root)},
+                    system_prompt_parts=('system prompt',),
+                    user_context={},
+                    system_context={},
+                    messages=(
+                        {'role': 'user', 'content': 'hello'},
+                        {
+                            'role': 'assistant',
+                            'content': '我先看看文件',
+                            'tool_calls': [
+                                {
+                                    'id': 'call-1',
+                                    'function': {'name': 'list_dir', 'arguments': '{}'},
+                                }
+                            ],
+                        },
+                        {
+                            'role': 'tool',
+                            'content': '',
+                            'tool_call_id': 'call-1',
+                            'state': 'streaming',
+                            'metadata': {'phase': 'starting'},
+                        },
+                    ),
+                    turns=1,
+                    tool_calls=1,
+                    usage={},
+                    total_cost_usd=0.0,
+                    file_history=(),
+                    budget_state={'status': 'running'},
+                    plugin_state={},
+                ),
+                directory=session_root,
+            )
+            state.run_manager.start('alice', 'thread-1')
+
+            response = client.post(
+                '/api/runs/cancel',
+                json={'account_id': 'alice', 'session_id': 'thread-1'},
+            )
+
+            self.assertEqual(response.status_code, 200)
+            self.assertTrue(response.json()['cancelled'])
+            stored = load_agent_session('thread-1', directory=session_root)
+            self.assertEqual(stored.messages[-1]['role'], 'assistant')
+            self.assertEqual(stored.messages[-1]['stop_reason'], 'cancelled')
+            self.assertEqual(
+                stored.messages[-1]['metadata']['status'],
+                'cancelled',
+            )
+            self.assertNotEqual(stored.messages[-1].get('state'), 'streaming')
+
+    def test_latest_run_reports_interrupted_for_orphaned_streaming_session(self) -> None:
+        with tempfile.TemporaryDirectory() as d:
+            root = Path(d)
+            client, _ = _build_client(root)
+            session_root = root / 'accounts' / 'alice' / 'sessions'
+            save_agent_session(
+                StoredAgentSession(
+                    session_id='thread-1',
+                    model_config={'model': 'test-model'},
+                    runtime_config={'cwd': str(root)},
+                    system_prompt_parts=('system prompt',),
+                    user_context={},
+                    system_context={},
+                    messages=(
+                        {'role': 'user', 'content': 'hello'},
+                        {
+                            'role': 'tool',
+                            'content': '',
+                            'tool_call_id': 'call-1',
+                            'state': 'streaming',
+                            'metadata': {'phase': 'starting'},
+                        },
+                    ),
+                    turns=1,
+                    tool_calls=1,
+                    usage={},
+                    total_cost_usd=0.0,
+                    file_history=(),
+                    budget_state={'status': 'running'},
+                    plugin_state={},
+                ),
+                directory=session_root,
+            )
+
+            response = client.get(
+                '/api/runs/latest',
+                params={'account_id': 'alice', 'session_id': 'thread-1'},
+            )
+
+            self.assertEqual(response.status_code, 200)
+            self.assertEqual(response.json()['status'], 'interrupted')
+
     def test_chat_uses_account_scoped_model_config(self) -> None:
         with tempfile.TemporaryDirectory() as d:
             client, _ = _build_client(Path(d))