fix: clean up background tasks on session exit (#641)

* fix: clean up background tasks on session exit

* Stop background tasks on session close

Change versioning for agent-core and kimi-code to patch.

Signed-off-by: 7Sageer <12210216@mail.sustech.edu.cn>

---------

Signed-off-by: 7Sageer <12210216@mail.sustech.edu.cn>

.changeset/stop-background-tasks-on-exit.md

@@ -0,0 +1,6 @@
+---
+"@moonshot-ai/agent-core": patch
+"@moonshot-ai/kimi-code": patch
+---
+
+Stop background tasks by default when sessions close.

docs/en/configuration/config-files.md

@@ -169,7 +169,7 @@ You can also switch models temporarily without touching the config file — by s
 | Field | Type | Default | Description |
 | --- | --- | --- | --- |
 | `max_running_tasks` | `integer` | — | Maximum number of background tasks running concurrently |
-| `keep_alive_on_exit` | `boolean` | `true` | Whether to keep still-running background tasks when the session closes. Set to `false` to request that all background tasks stop before the process exits |
+| `keep_alive_on_exit` | `boolean` | `false` | Whether to keep still-running background tasks when the session closes. By default, Kimi Code requests that all background tasks stop before the process exits; set this to `true` only when you want tasks to outlive the session |
 
 `keep_alive_on_exit` can be overridden by the `KIMI_CODE_BACKGROUND_KEEP_ALIVE_ON_EXIT` environment variable, which takes higher priority than `config.toml`.
 

docs/en/configuration/env-vars.md

@@ -123,7 +123,7 @@ Switches that control the behavior of subsystems such as telemetry, background t
 | Variable | Purpose | Valid values |
 | --- | --- | --- |
 | `KIMI_DISABLE_TELEMETRY` | Disable anonymous telemetry reporting | `1`, `true`, `yes`, `y` (case-insensitive) |
-| `KIMI_CODE_BACKGROUND_KEEP_ALIVE_ON_EXIT` | Whether to keep background tasks when the session closes; takes higher priority than `config.toml` | Truthy: `1`/`true`/`yes`/`on`; falsy: `0`/`false`/`no`/`off` |
+| `KIMI_CODE_BACKGROUND_KEEP_ALIVE_ON_EXIT` | Whether to keep background tasks when the session closes; takes higher priority than `config.toml`. The default is to stop them on exit | Truthy: `1`/`true`/`yes`/`on`; falsy: `0`/`false`/`no`/`off` |
 | `KIMI_CODE_PLUGIN_MARKETPLACE_URL` | Override the plugin marketplace JSON loaded by `/plugins` | URL or local path |
 | `KIMI_CODE_EXPERIMENTAL_FLAG` | Enable all registered experimental features for this process; `micro_compaction` is already enabled by default | `1`, `true`, `yes`, `on` |
 | `KIMI_CODE_EXPERIMENTAL_MICRO_COMPACTION` | Override [`[experimental].micro_compaction`](./config-files.md#experimental) for this process | Truthy or falsy |

docs/zh/configuration/config-files.md

@@ -169,7 +169,7 @@ max_context_size = 1047576
 | 字段 | 类型 | 默认值 | 说明 |
 | --- | --- | --- | --- |
 | `max_running_tasks` | `integer` | — | 同时运行的最大后台任务数 |
-| `keep_alive_on_exit` | `boolean` | `true` | 会话关闭时是否保留仍在运行的后台任务。设为 `false` 时，进程退出前会请求停止所有后台任务 |
+| `keep_alive_on_exit` | `boolean` | `false` | 会话关闭时是否保留仍在运行的后台任务。默认情况下，Kimi Code 会在进程退出前请求停止所有后台任务；只有希望任务在会话结束后继续运行时才设为 `true` |
 
 `keep_alive_on_exit` 可被环境变量 `KIMI_CODE_BACKGROUND_KEEP_ALIVE_ON_EXIT` 覆盖，优先级高于配置文件。
 

docs/zh/configuration/env-vars.md

@@ -123,7 +123,7 @@ kimi
 | 环境变量 | 用途 | 合法值 |
 | --- | --- | --- |
 | `KIMI_DISABLE_TELEMETRY` | 关闭匿名遥测上报 | `1`、`true`、`yes`、`y`（不区分大小写） |
-| `KIMI_CODE_BACKGROUND_KEEP_ALIVE_ON_EXIT` | 会话关闭时是否保留后台任务，优先级高于 `config.toml` | 真值：`1`/`true`/`yes`/`on`；假值：`0`/`false`/`no`/`off` |
+| `KIMI_CODE_BACKGROUND_KEEP_ALIVE_ON_EXIT` | 会话关闭时是否保留后台任务，优先级高于 `config.toml`。默认会在退出时停止后台任务 | 真值：`1`/`true`/`yes`/`on`；假值：`0`/`false`/`no`/`off` |
 | `KIMI_CODE_PLUGIN_MARKETPLACE_URL` | 替换 `/plugins` 加载的 marketplace JSON | URL 或本地路径 |
 | `KIMI_CODE_EXPERIMENTAL_FLAG` | 在当前进程启用所有已注册的实验功能；`micro_compaction` 已默认开启 | `1`、`true`、`yes`、`on` |
 | `KIMI_CODE_EXPERIMENTAL_MICRO_COMPACTION` | 覆盖当前进程的 [`[experimental].micro_compaction`](./config-files.md#experimental) | 真值或假值 |

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

@@ -264,7 +264,7 @@ export class Session {
       env: process.env,
       envKey: BACKGROUND_KEEP_ALIVE_ON_EXIT_ENV,
       configValue: this.options.background?.keepAliveOnExit,
-      defaultValue: true,
+      defaultValue: false,
       parseEnv: parseBooleanEnv,
     });
     if (keepAliveOnExit) return;

packages/agent-core/test/session/lifecycle-hooks.test.ts

@@ -110,7 +110,7 @@ describe('Session lifecycle hooks', () => {
     await expect(session.close()).resolves.toBeUndefined();
   });
 
-  it('stops background tasks on close when keepAliveOnExit is false', async () => {
+  it('stops background tasks on close by default', async () => {
     const { sessionDir, workDir } = await hookFixture();
     const session = new Session({
       kaos: testKaos.withCwd(workDir),
@@ -118,7 +118,6 @@ describe('Session lifecycle hooks', () => {
       homedir: sessionDir,
       rpc: createSessionRpc(),
       skills: { explicitDirs: [join(workDir, 'missing-skills')] },
-      background: { keepAliveOnExit: false },
     });
     const agent = await session.createMain();
     const { proc, killSpy } = pendingProcess();
@@ -132,6 +131,28 @@ describe('Session lifecycle hooks', () => {
     expect(agent.background.getTask(taskId)?.status).toBe('killed');
   });
 
+  it('keeps background tasks alive on close when keepAliveOnExit is true', async () => {
+    const { sessionDir, workDir } = await hookFixture();
+    const session = new Session({
+      kaos: testKaos.withCwd(workDir),
+      id: 'session-bg-keepalive',
+      homedir: sessionDir,
+      rpc: createSessionRpc(),
+      skills: { explicitDirs: [join(workDir, 'missing-skills')] },
+      background: { keepAliveOnExit: true },
+    });
+    const agent = await session.createMain();
+    const { proc, killSpy } = pendingProcess();
+    const taskId = agent.background.registerTask(
+      new ProcessBackgroundTask(proc, 'sleep 60', 'keep alive'),
+    );
+
+    await session.close();
+
+    expect(killSpy).not.toHaveBeenCalled();
+    expect(agent.background.getTask(taskId)?.status).toBe('running');
+  });
+
   it('lets the environment override config when deciding background task cleanup', async () => {
     vi.stubEnv('KIMI_CODE_BACKGROUND_KEEP_ALIVE_ON_EXIT', '0');
     const { sessionDir, workDir } = await hookFixture();