fix: clarify subagent and background task stop messages as user-initiated

.changeset/subagent-stop-wording.md

@@ -0,0 +1,6 @@
+---
+"@moonshot-ai/agent-core": patch
+"@moonshot-ai/kimi-code": patch
+---
+
+Clarify subagent and background task stop messages as user-initiated.

apps/kimi-code/src/tui/controllers/tasks-browser.ts

@@ -309,7 +309,7 @@ export class TasksBrowserController {
 
     this.flash(`Stopping ${taskId}…`, 1500);
     try {
-      await session.stopBackgroundTask(taskId, { reason: 'stopped from /tasks' });
+      await session.stopBackgroundTask(taskId, { reason: 'User initiated stop' });
       await this.refresh({ silent: true });
     } catch (error) {
       const message = error instanceof Error ? error.message : String(error);

packages/agent-core/src/agent/background/index.ts

@@ -135,7 +135,10 @@ export class BackgroundManager extends BackgroundProcessManager {
       source_id: info.taskId,
       title: `Background ${label} ${info.status}`,
       severity: info.status === 'completed' ? 'info' : 'warning',
-      body: `${info.description} ${info.status}.`,
+      body:
+        info.status === 'killed' && info.stopReason
+          ? `${info.description} was killed: ${info.stopReason}.`
+          : `${info.description} ${info.status}.`,
       tail_output: tailOutput,
     };
     const content = [

packages/agent-core/src/tools/builtin/collaboration/agent.ts

@@ -21,6 +21,7 @@ import { z } from 'zod';
 import type { BuiltinTool } from '../../../agent/tool';
 import type { Logger } from '../../../logging';
 import { ToolAccesses } from '../../../loop/tool-access';
+import { isAbortError } from '../../../loop/errors';
 import type { ExecutableToolContext, ExecutableToolResult, ToolExecution } from '../../../loop/types';
 import type { ResolvedAgentProfile } from '../../../profile';
 import type { SessionSubagentHost, SubagentHandle } from '../../../session/subagent-host';
@@ -299,12 +300,14 @@ export class AgentTool implements BuiltinTool<AgentToolInput> {
         ];
         return { output: lines.join('\n') };
       } catch (error) {
-        const message =
-          foregroundDeadline?.timedOut() === true && args.timeout !== undefined
-            ? `Agent timed out after ${args.timeout}s.`
-            : error instanceof Error
-              ? error.message
-              : String(error);
+        let message: string;
+        if (foregroundDeadline?.timedOut() === true && args.timeout !== undefined) {
+          message = `Agent timed out after ${args.timeout}s.`;
+        } else if (isAbortError(error)) {
+          message = 'The subagent was stopped by the user.';
+        } else {
+          message = error instanceof Error ? error.message : String(error);
+        }
         const lines = [
           `agent_id: ${handle.agentId}`,
           `actual_subagent_type: ${handle.profileName}`,
@@ -315,12 +318,14 @@ export class AgentTool implements BuiltinTool<AgentToolInput> {
         return { output: lines.join('\n'), isError: true };
       }
     } catch (error) {
-      const message =
-        foregroundDeadline?.timedOut() === true && args.timeout !== undefined
-          ? `Agent timed out after ${args.timeout}s.`
-          : error instanceof Error
-            ? error.message
-            : String(error);
+      let message: string;
+      if (foregroundDeadline?.timedOut() === true && args.timeout !== undefined) {
+        message = `Agent timed out after ${args.timeout}s.`;
+      } else if (isAbortError(error)) {
+        message = 'The subagent was stopped by the user.';
+      } else {
+        message = error instanceof Error ? error.message : String(error);
+      }
       return { output: `subagent error: ${message}`, isError: true };
     } finally {
       foregroundDeadline?.clear();

packages/agent-core/src/tools/builtin/shell/bash.ts

@@ -430,7 +430,7 @@ export class BashTool implements BuiltinTool<BashInput> {
           }
           const info = backgroundManager.getTask(taskId);
           if (info && info.status === 'running') {
-            void backgroundManager.stop(taskId);
+            void backgroundManager.stop(taskId, 'Timed out');
           }
         })();
       }, timeoutMs);