feat(agent-core): drop default timeouts for print-mode background tasks (#1737)

* feat(agent-core): drop default timeouts for print-mode background tasks

- add `bash_task_timeout_s` config under [background] (0 = no timeout),
  covering the background Bash default and the re-arm after a foreground
  command is moved to the background on timeout
- allow `[subagent] timeout_ms = 0` (no timeout) and thread it through
  Agent/AgentSwarm task registration and the swarm batch timer
- fill both with 0 in print-mode config defaults so `kimi -p` never kills
  background work by wall-clock and only the model stops a task;
  interactive defaults are unchanged
- sync the Bash tool description/parameter text with the effective
  default and update user docs (en/zh) plus changeset

* test(agent-core): satisfy KimiConfig providers requirement in print-defaults tests

* fix(agent-core): clear the foreground deadline on detach when the background timeout is disabled

`detach()` only re-arms when `detachTimeoutMs` is defined, so passing
`undefined` with `bash_task_timeout_s = 0` kept the armed foreground
deadline and a manually detached command was still killed at its
foreground timeout. Pass `0` instead so the reset clears the timer.
Caught by Codex review on #1737.

Author: sailist

.changeset/print-no-background-timeouts.md

@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": minor
+---
+
+In print mode (`kimi -p`), background Bash tasks and subagents no longer have a timeout by default — they run until they finish or the model stops them, and a foreground Bash command that times out is moved to the background without a new deadline. Interactive defaults are unchanged; tune per mode with `bash_task_timeout_s` under `[background]` or `timeout_ms` under `[subagent]` (`0` = no timeout).

docs/en/configuration/config-files.md

@@ -210,20 +210,21 @@ You can also switch models temporarily without touching the config file — by s
 | `max_running_tasks` | `integer` | — | Maximum number of background tasks running concurrently |
 | `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. In print mode (`kimi -p`), this is only a legacy fallback used when `print_background_mode` is unset: `true` is equivalent to `print_background_mode = "drain"` |
 | `kill_grace_period_ms` | `integer` | `5000` | Grace period in milliseconds after session close, a manual stop, or a task timeout requests graceful termination. If a task is still running after this period, Kimi Code attempts to force-stop it |
-| `bash_auto_background_on_timeout` | `boolean` | `true` | When a foreground `Bash` command hits its timeout, move it to a background task instead of killing it — the agent is notified when it completes, and the backgrounded command is bounded by the 600s default background timeout. Set to `false` to kill timed-out foreground commands instead |
-| `print_background_mode` | `"exit" \| "drain" \| "steer"` | `"exit"` | Print mode (`kimi -p`) only. Governs how pending background tasks are handled once the main agent's turn ends: `"exit"` exits immediately; `"drain"` waits for every background task to reach a terminal state before exiting (results are not fed back to the main agent); `"steer"` stays alive so a completing background task — like a background subagent — injects a synthetic user message that steers the main agent into a new turn, looping until a turn ends with no pending background tasks or a limit is hit. Takes precedence over the `keep_alive_on_exit` print fallback |
-| `print_wait_ceiling_s` | `integer` | `3600` | In print mode (`kimi -p`), the wall-clock ceiling (seconds) for the wait/steer loop when `print_background_mode` is `"drain"` or `"steer"`. Has no effect outside print mode or when it is `"exit"` |
-| `print_max_turns` | `integer` | `50` | In print mode (`kimi -p`) with `print_background_mode = "steer"`, the maximum number of new turns that may be triggered by background-task completions, to keep the steering loop bounded |
+| `bash_auto_background_on_timeout` | `boolean` | `true` | When a foreground `Bash` command hits its timeout, move it to a background task instead of killing it — the agent is notified when it completes, and the backgrounded command is bounded by the `bash_task_timeout_s` default background timeout. Set to `false` to kill timed-out foreground commands instead |
+| `bash_task_timeout_s` | `integer` | `600` | Default timeout (seconds) for background `Bash` tasks when the call omits `timeout`; also used to re-arm foreground commands moved to the background on timeout. `0` means no timeout — the task runs until it exits or the model stops it. Explicit per-call `timeout` values are unaffected. In print mode (`kimi -p`) the default is `0` unless explicitly set |
+| `print_background_mode` | `"exit" \| "drain" \| "steer"` | `"steer"` | Print mode (`kimi -p`) only. Governs how pending background tasks are handled once the main agent's turn ends: `"exit"` exits immediately; `"drain"` waits for every background task to reach a terminal state before exiting (results are not fed back to the main agent); `"steer"` stays alive so a completing background task — like a background subagent — injects a synthetic user message that steers the main agent into a new turn, looping until a turn ends with no pending background tasks or a limit is hit. Takes precedence over the `keep_alive_on_exit` print fallback |
+| `print_wait_ceiling_s` | `integer` | `315360000` | In print mode (`kimi -p`), the wall-clock ceiling (seconds) for the wait/steer loop when `print_background_mode` is `"drain"` or `"steer"` (the default is 10 years — effectively unbounded). Has no effect outside print mode or when it is `"exit"` |
+| `print_max_turns` | `integer` | `100000` | In print mode (`kimi -p`) with `print_background_mode = "steer"`, the maximum number of new turns that may be triggered by background-task completions, to keep the steering loop bounded (the default is effectively unbounded) |
 
 `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`.
 
-In print mode (`kimi -p "<prompt>"`), Kimi Code by default runs a single non-interactive turn and exits as soon as the main agent finishes (`print_background_mode = "exit"`). If you launch background tasks (for example, concurrent subagents via `Agent(run_in_background=true)`, or a long command via `Bash(run_in_background=true)`) and need them to run to completion, set `print_background_mode` to `"drain"` (wait for them to finish, without feeding results back) or `"steer"` (feed each completion back to the main agent, starting a new turn so it can act on the result). `"steer"` is useful when the main agent should keep working based on the outcome of a long background task (e.g. training or evaluation); its total wall-clock is bounded by `print_wait_ceiling_s` and the number of extra turns by `print_max_turns`.
+In print mode (`kimi -p "<prompt>"`), Kimi Code stays alive after the main agent's turn as long as background tasks are still pending: each completion is fed back to the main agent as a synthetic user message, steering it into a new turn (`print_background_mode = "steer"` by default), and the run exits once a turn ends with nothing pending. The loop is bounded by `print_wait_ceiling_s` and `print_max_turns`, both effectively unbounded by default. Background work is never killed by a wall-clock cap in print mode either: background `Bash` tasks default to no timeout (`bash_task_timeout_s = 0`), and subagents run without a timeout (`[subagent] timeout_ms = 0`), so only the model itself stops a task. Set `print_background_mode` to `"drain"` to wait for tasks without feeding results back, or `"exit"` to end the run as soon as the main agent finishes.
 
 ## `subagent`
 
 | Field | Type | Default | Description |
 | --- | --- | --- | --- |
-| `timeout_ms` | `integer` | `7200000` (2 hours) | Maximum wall-clock time (milliseconds) a single subagent (`Agent` / `AgentSwarm`) is allowed to run before it is settled as `timed_out`. Set a very large value (e.g. `259200000`, i.e. 3 days) to effectively lift the cap. This is the background-task manager's per-task timeout for each subagent task, so it applies to both foreground and background subagents. Note: any value above `2147483647` (about 24.8 days) is clamped to 1ms by the runtime. |
+| `timeout_ms` | `integer` | `7200000` (2 hours) | Maximum wall-clock time (milliseconds) a single subagent (`Agent` / `AgentSwarm`) is allowed to run before it is settled as `timed_out`. `0` means no timeout — the subagent runs until it finishes or the model stops it. This is the background-task manager's per-task timeout for each subagent task, so it applies to both foreground and background subagents. In print mode (`kimi -p`) the default is `0` unless explicitly set. Note: any value above `2147483647` (about 24.8 days) is clamped to roughly 24.8 days by the runtime |
 
 `timeout_ms` can be overridden by the `KIMI_SUBAGENT_TIMEOUT_MS` environment variable, which takes higher priority than `config.toml`.
 

docs/en/reference/tools.md

@@ -40,11 +40,11 @@ File tools handle reading, writing, and searching the local filesystem — the f
 - `command` (required): the shell command to execute
 - `cwd`: working directory
 - `timeout`: timeout in milliseconds; foreground default is 60 seconds, maximum is 5 minutes
-- `run_in_background`: whether to run as a background task; background tasks default to a 10-minute timeout
+- `run_in_background`: whether to run as a background task; background tasks default to a 10-minute timeout (no timeout by default in print mode `kimi -p`)
 - `description`: background task description; required when `run_in_background=true`
 - `disable_timeout`: whether to remove the timeout limit for background tasks
 
-Foreground mode blocks the current turn until the command completes or times out, and the TUI streams stdout and stderr into the running `Bash` tool card while the command is still active. By default, a foreground command that hits its timeout is not killed — it keeps running as a background task (bounded by the 600s default background timeout); to restore kill-on-timeout, set [`bash_auto_background_on_timeout`](../configuration/config-files.md#background) to `false` under `[background]`. Background mode returns a task ID immediately and automatically notifies the Agent when the task finishes. stdin is always closed — interactive commands receive EOF immediately. A two-phase termination strategy (SIGTERM → 5-second grace period → SIGKILL) ensures reliable process cleanup when a task is stopped or hits its background timeout. On Windows, Git Bash is used by default.
+Foreground mode blocks the current turn until the command completes or times out, and the TUI streams stdout and stderr into the running `Bash` tool card while the command is still active. By default, a foreground command that hits its timeout is not killed — it keeps running as a background task (bounded by the 600s default background timeout); to restore kill-on-timeout, set [`bash_auto_background_on_timeout`](../configuration/config-files.md#background) to `false` under `[background]`. The 600s background default is configurable via [`bash_task_timeout_s`](../configuration/config-files.md#background) (`0` = no timeout) and defaults to no timeout in print mode (`kimi -p`). Background mode returns a task ID immediately and automatically notifies the Agent when the task finishes. stdin is always closed — interactive commands receive EOF immediately. A two-phase termination strategy (SIGTERM → 5-second grace period → SIGKILL) ensures reliable process cleanup when a task is stopped or hits its background timeout. On Windows, Git Bash is used by default.
 
 ## Web Tools
 
@@ -89,7 +89,7 @@ Collaboration tools handle inter-Agent coordination, user interaction, and Skill
 | `AskUserQuestion` | Auto-allow | Ask the user a question to gather structured input |
 | `Skill` | Auto-allow | Invoke a registered inline Skill |
 
-**`Agent`** delegates a subtask to a sub-Agent. Required parameters: `prompt` (complete task description) and `description` (a 3–5 word short summary). Optional parameters: `subagent_type` (defaults to `coder`), `resume` (ID of an existing Agent to resume; mutually exclusive with `subagent_type`), and `run_in_background` (defaults to false). Agent tasks time out after 2 hours by default; the limit is configurable via `[subagent] timeout_ms` in `config.toml` (or the `KIMI_SUBAGENT_TIMEOUT_MS` env var). In foreground mode the parent Agent waits for the sub-Agent to complete before continuing; in background mode a task ID is returned immediately and the result is automatically delivered back to the main Agent via a synthetic User message when done. When several foreground `Agent` calls run in the same step, the TUI groups them and shows each subagent's running, waiting, completed, or failed status with elapsed time. See [Agent & Sub-Agents](../customization/agents.md) for details.
+**`Agent`** delegates a subtask to a sub-Agent. Required parameters: `prompt` (complete task description) and `description` (a 3–5 word short summary). Optional parameters: `subagent_type` (defaults to `coder`), `resume` (ID of an existing Agent to resume; mutually exclusive with `subagent_type`), and `run_in_background` (defaults to false). Agent tasks time out after 2 hours by default; the limit is configurable via `[subagent] timeout_ms` in `config.toml` (`0` = no timeout, or the `KIMI_SUBAGENT_TIMEOUT_MS` env var), and defaults to no timeout in print mode (`kimi -p`). In foreground mode the parent Agent waits for the sub-Agent to complete before continuing; in background mode a task ID is returned immediately and the result is automatically delivered back to the main Agent via a synthetic User message when done. When several foreground `Agent` calls run in the same step, the TUI groups them and shows each subagent's running, waiting, completed, or failed status with elapsed time. See [Agent & Sub-Agents](../customization/agents.md) for details.
 
 **`AgentSwarm`** launches subagents from a shared `prompt_template` and an `items` array, resumes existing subagents through `resume_agent_ids`, or combines both in one call. The template must contain the `{{item}}` placeholder; each item replaces that placeholder and launches one new subagent. Pass `subagent_type` to choose the profile used by every spawned subagent in the swarm, or omit it to use `coder`. Without `resume_agent_ids`, the tool requires at least 2 items; with `resume_agent_ids`, it can resume one or more existing subagents. The tool supports up to 128 total subagents, waits for all subagents to finish, and returns an aggregated report. In the TUI, foreground swarms show a live `Agent swarm` progress panel above the input box. If a model response calls `AgentSwarm`, that call must be the only tool call in the response; to run multiple swarms, call one `AgentSwarm`, wait for its result, then call the next, or combine the work into one swarm when a single template can cover it. In `manual` permission mode, `AgentSwarm` calls outside active swarm mode request approval unless a permission rule allows them; while swarm mode is active, `AgentSwarm` itself is auto-approved. Permission rules match `AgentSwarm` by tool name only — argument patterns such as `AgentSwarm(swarm)` are not supported. By default the tool ramps up concurrency without an upper limit (5 subagents start immediately, then 1 more every 700 ms); set `KIMI_CODE_AGENT_SWARM_MAX_CONCURRENCY` to a positive integer to cap how many subagents run at the same time during that ramp, or leave it unset for no cap. If it is set to a value that is not a positive integer, the AgentSwarm call fails fast.