feat(secondary-model): graduate the subagent model pool out of experimental

.changeset/secondary-model-default-on.md

@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": minor
+---
+
+The subagent model pool (`[secondary_model]`) now works without the removed `secondary-model` experiment — subagents bind the pool's `default_model`, and the `KIMI_CODE_EXPERIMENTAL_SECONDARY_MODEL` env var no longer has any effect.

apps/kimi-code/src/tui/commands/config.ts

@@ -648,21 +648,26 @@ function showSecondaryModelPicker(
 }
 
 /**
- * Persists `[secondary_model] default_model`. When a
+ * Persists `[secondary_model] default_model` (and the legacy `model` key the
+ * v1 engine binds from — same alias, so both engines pick it up). When a
  * `[secondary_model.models]` pool exists and does not list the alias yet, the
  * alias is added with an empty description — the engine requires the default
  * to be a pool key. Without a pool the default alone forms an implicit
- * single-entry pool, so nothing else is written. No live-apply step: the
- * engine resolves the pool per spawn, so the next subagent dispatch picks the
- * new value up on its own.
+ * single-entry pool, so nothing else is written. The v2 engine resolves the
+ * pool per spawn, and the v1 core live-applies the saved snapshot to every
+ * live session on config write, so the next subagent dispatch picks the new
+ * value up on its own.
  */
 async function performSecondaryModelSave(host: SlashCommandHost, alias: string): Promise<void> {
   const displayName = modelDisplayName(alias, host.state.appState.availableModels[alias]);
   try {
     const config = await host.harness.getConfig({ reload: true });
     const existing = config.secondaryModel?.models;
-    const patch: { defaultModel: string; models?: Record<string, string> } = {
+    // Write both keys: the v1 legacy engine binds `.model`, the v2 pool reads
+    // `defaultModel` — keeping only one would leave the other engine stale.
+    const patch: { defaultModel: string; model: string; models?: Record<string, string> } = {
       defaultModel: alias,
+      model: alias,
     };
     if (existing !== undefined) {
       patch.models = { ...existing, [alias]: existing[alias] ?? '' };

apps/kimi-code/src/tui/commands/registry.ts

@@ -216,7 +216,6 @@ export const BUILTIN_SLASH_COMMANDS = [
     description: 'Configure the secondary model for subagents',
     priority: 90,
     availability: 'always',
-    experimentalFlag: 'secondary-model',
   },
   {
     name: 'effort',

apps/kimi-code/test/tui/commands/registry.test.ts

@@ -209,10 +209,10 @@ describe('built-in slash command registry', () => {
     expect(resolveSlashCommandAvailability(reloadTui!, '')).toBe('always');
   });
 
-  it('gates secondary-model behind the secondary-model experiment, always available', () => {
+  it('registers secondary-model unconditionally, always available', () => {
     const command = findBuiltInSlashCommand('secondary-model');
     expect(command).toBeDefined();
-    expect((command as KimiSlashCommand).experimentalFlag).toBe('secondary-model');
+    expect((command as KimiSlashCommand).experimentalFlag).toBeUndefined();
     expect(resolveSlashCommandAvailability(command!, '')).toBe('always');
   });
 

apps/kimi-code/test/tui/commands/secondary-model.test.ts

@@ -112,7 +112,7 @@ describe('handleSecondaryModelCommand', () => {
       expect(host.showStatus).toHaveBeenCalled();
     });
     expect(host.harness.setConfig).toHaveBeenCalledWith({
-      secondaryModel: { defaultModel: 'k2' },
+      secondaryModel: { defaultModel: 'k2', model: 'k2' },
     });
     expect(host.showError).not.toHaveBeenCalled();
   });
@@ -134,6 +134,7 @@ describe('handleSecondaryModelCommand', () => {
     expect(host.harness.setConfig).toHaveBeenCalledWith({
       secondaryModel: {
         defaultModel: 'k2',
+        model: 'k2',
         models: { cheap: 'fast and cheap', k2: '' },
       },
     });
@@ -156,6 +157,7 @@ describe('handleSecondaryModelCommand', () => {
     expect(host.harness.setConfig).toHaveBeenCalledWith({
       secondaryModel: {
         defaultModel: 'k2',
+        model: 'k2',
         models: { cheap: 'fast and cheap', k2: 'hard tasks' },
       },
     });

docs/en/configuration/config-files.md

@@ -196,7 +196,7 @@ Subagents inherit the model the main agent is running by default. The `[secondar
 
 ### Subagent model pool
 
-This feature is experimental and disabled by default. Enable it with `KIMI_CODE_EXPERIMENTAL_SECONDARY_MODEL=1`, or the master `KIMI_CODE_EXPERIMENTAL_FLAG=1`; it takes effect in every launch mode, including the interactive TUI. While the experiment is off, the pool keys stay inert: subagents inherit the caller's model and session startup skips the pool validation.
+Configured values take effect in every launch mode, including the interactive TUI.
 
 The minimal configuration is one line — a lone `default_model` is a pool with a single entry:
 

docs/en/configuration/env-vars.md

@@ -150,7 +150,6 @@ Switches that control the behavior of subsystems such as telemetry, background t
 | `KIMI_CODE_IDENTITY_SLUG` | Protocol identifier for the `User-Agent` product token sent to third-party providers and the MCP client name; takes higher priority than `[identity] slug`. Derived from the name when unset | Any non-empty string; normalized to lowercase with non-alphanumeric runs folded to `-` |
 | `KIMI_CODE_BUILTIN_PRODUCT_SKILLS` | Whether the built-in skills documenting Kimi Code itself are offered to the model; takes higher priority than `builtin_product_skills` in `config.toml` (default enabled) | Truthy: `1`/`true`/`yes`/`on`; falsy: `0`/`false`/`no`/`off` |
 | `KIMI_CODE_TUI_FULL_SCREEN` | Enable the experimental fullscreen alternate-screen UI: scrollable transcript viewport, mouse text selection, clickable links, and Ctrl-Shift-F transcript search | `1` enables it; anything else keeps the regular inline UI |
-| `KIMI_CODE_EXPERIMENTAL_SECONDARY_MODEL` | Enable the experimental [subagent model pool](./config-files.md#subagent-model-pool) in every launch mode, including the interactive TUI; the master `KIMI_CODE_EXPERIMENTAL_FLAG=1` also enables it | Truthy: `1`/`true`/`yes`/`on`; falsy: `0`/`false`/`no`/`off` |
 | `KIMI_CODE_EXPERIMENTAL_SUBAGENT_FORK` | Enable the experimental `fork` parameter on the `Agent` and `AgentSwarm` tools, letting the model start a subagent with a snapshot of the calling agent's conversation history instead of an empty context; the master `KIMI_CODE_EXPERIMENTAL_FLAG=1` also enables it | Truthy: `1`/`true`/`yes`/`on`; falsy: `0`/`false`/`no`/`off` |
 | `KIMI_MCP_STARTUP_TIMEOUT_MS` | Global default connection timeout (ms) for all MCP servers; takes higher priority than `[mcp] startup_timeout_ms` in `config.toml`, but a per-server `startupTimeoutMs` in `mcp.json` still wins (default `30000`) | Integer from `1` to `2147483647`; invalid values are ignored |
 | `KIMI_MCP_TOOL_TIMEOUT_MS` | Global default single tool-call timeout (ms) for all MCP servers; takes higher priority than `[mcp] tool_timeout_ms` in `config.toml`, but a per-server `toolTimeoutMs` in `mcp.json` still wins (default `60000`) | Integer from `1` to `2147483647`; invalid values are ignored |

docs/en/reference/slash-commands.md

@@ -16,7 +16,7 @@ Some commands are only available in the idle state. Executing these commands whi
 | `/logout` | — | Clear credentials for the currently selected account | No |
 | `/provider` | — | Open the interactive provider manager to view, add, and remove configured providers. See [Platforms & Models — `/provider` and provider management](../configuration/providers.md#provider-—-interactive-provider-management) | Yes |
 | `/model` | — | Switch the LLM model used in the current session | Yes |
-| `/secondary-model` | `/subagent-model` | Pick the default model for subagents (writes `[secondary_model] default_model`; see the [subagent model pool](../configuration/config-files.md#subagent-model-pool)). Visible when the subagent model pool experiment is enabled | Yes |
+| `/secondary-model` | `/subagent-model` | Pick the default model for subagents (writes `[secondary_model] default_model`; see the [subagent model pool](../configuration/config-files.md#subagent-model-pool)) | Yes |
 | `/settings` | `/config` | Open the settings panel inside the TUI | Yes |
 | `/experiments` | `/experimental` | Open the experimental feature panel | Yes |
 | `/permission` | — | Select a permission mode | Yes |

docs/en/reference/tools.md

@@ -89,9 +89,9 @@ 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`), `run_in_background` (defaults to false), and `model` (available only when the [subagent model pool](../configuration/config-files.md#subagent-model-pool) experiment is enabled and a pool is configured — a `[secondary_model.models]` table or a lone `default_model`: a pool alias, or `"primary"` for the model the caller itself is running; ignored when resuming). Without it, the subagent binds the pool's `default_model`; without a configured pool, subagents always inherit the caller's model. 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.
+**`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`), `run_in_background` (defaults to false), and `model` (available when a [subagent model pool](../configuration/config-files.md#subagent-model-pool) is configured — either a `[secondary_model.models]` table or a lone `default_model`: a pool alias, or `"primary"` for the model the caller itself is running; ignored when resuming). Without it, the subagent binds the pool's `default_model`; without a configured pool, subagents always inherit the caller's model. 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`. Pass `model` (available only when the [subagent model pool](../configuration/config-files.md#subagent-model-pool) experiment is enabled and a pool is configured — a `[secondary_model.models]` table or a lone `default_model`) to run item-spawned subagents on a pool alias or on the caller's own model (`"primary"`). Without it, item-spawned subagents bind the pool's `default_model`; without a configured pool, they inherit the caller's model. Resumed subagents keep their own model. 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. Each subagent times out after 2 hours by default; the limit is configurable via [`[swarm] timeout_ms`](../configuration/config-files.md#swarm) in `config.toml` (`0` = no timeout, or the `KIMI_CODE_SWARM_TIMEOUT_MS` env var), and defaults to no timeout in print mode (`kimi -p`). A timed-out subagent is aborted and marked as failed in the 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.
+**`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`. Pass `model` (available when a [subagent model pool](../configuration/config-files.md#subagent-model-pool) is configured — a `[secondary_model.models]` table or a lone `default_model`) to run item-spawned subagents on a pool alias or on the caller's own model (`"primary"`). Without it, item-spawned subagents bind the pool's `default_model`; without a configured pool, they inherit the caller's model. Resumed subagents keep their own model. 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. Each subagent times out after 2 hours by default; the limit is configurable via [`[swarm] timeout_ms`](../configuration/config-files.md#swarm) in `config.toml` (`0` = no timeout, or the `KIMI_CODE_SWARM_TIMEOUT_MS` env var), and defaults to no timeout in print mode (`kimi -p`). A timed-out subagent is aborted and marked as failed in the 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.
 
 **`AskUserQuestion`** asks the user a structured multiple-choice question — useful for disambiguation or option selection. The `questions` parameter accepts 1–4 questions; each question requires `question` (ending with `?`), `options` (2–4 choices, each with a `label` and `description`), and optional `header` (max 12 characters) and `multi_select` (defaults to false). An "Other" option is appended automatically. Setting `background` to true starts a background question task and returns a task ID immediately. When the host does not support interactive questioning, a failure message is returned and the Agent should ask the user directly in a text reply instead.
 

docs/zh/configuration/config-files.md

@@ -196,7 +196,7 @@ subagent 默认继承 main agent 正在运行的模型。`[secondary_model]` 节
 
 ### subagent 模型池
 
-该功能目前是实验功能，默认关闭。通过 `KIMI_CODE_EXPERIMENTAL_SECONDARY_MODEL=1` 启用，或使用 master `KIMI_CODE_EXPERIMENTAL_FLAG=1`，在包括交互式 TUI 在内的所有启动方式下生效。实验功能关闭时模型池配置不生效：subagent 继承调用方模型，会话启动也会跳过池校验。
+配置后在包括交互式 TUI 在内的所有启动方式下生效。
 
 最小配置只有一行——单独写下的 `default_model` 就是只含一个条目的模型池：
 

docs/zh/configuration/env-vars.md

@@ -150,7 +150,6 @@ kimi
 | `KIMI_CODE_IDENTITY_SLUG` | 协议标识，用于发给第三方 provider 的 `User-Agent` 产品名和 MCP 客户端名，优先级高于 `[identity] slug`。未设置时由名称派生 | 任意非空字符串；会转小写并将连续非字母数字字符折叠为 `-` |
 | `KIMI_CODE_BUILTIN_PRODUCT_SKILLS` | 是否向模型提供介绍 Kimi Code 自身的内置 Skills，优先级高于 `config.toml` 的 `builtin_product_skills`（默认开启） | 真值：`1`/`true`/`yes`/`on`；假值：`0`/`false`/`no`/`off` |
 | `KIMI_CODE_TUI_FULL_SCREEN` | 启用实验性的 fullscreen alternate-screen 界面：可滚动的 transcript 视口、鼠标选择文本、可点击链接、Ctrl-Shift-F 搜索 | `1` 开启；其他值保持常规内联界面 |
-| `KIMI_CODE_EXPERIMENTAL_SECONDARY_MODEL` | 在包括交互式 TUI 在内的所有启动方式下启用实验性的[subagent 模型池](./config-files.md#subagent-模型池)；master `KIMI_CODE_EXPERIMENTAL_FLAG=1` 也会启用本功能 | 真值：`1`/`true`/`yes`/`on`；假值：`0`/`false`/`no`/`off` |
 | `KIMI_CODE_EXPERIMENTAL_SUBAGENT_FORK` | 在 `Agent` 和 `AgentSwarm` 工具上启用实验性的 `fork` 参数，让模型可以以调用方 Agent 对话历史的快照而不是空上下文启动 subagent；master `KIMI_CODE_EXPERIMENTAL_FLAG=1` 也会启用本功能 | 真值：`1`/`true`/`yes`/`on`；假值：`0`/`false`/`no`/`off` |
 | `KIMI_MCP_STARTUP_TIMEOUT_MS` | 所有 MCP server 的全局默认连接超时（毫秒）；优先级高于 `config.toml` 的 `[mcp] startup_timeout_ms`，但低于 `mcp.json` 中单个 server 的 `startupTimeoutMs`（默认 `30000`） | `1` 到 `2147483647` 的整数；非法值被忽略 |
 | `KIMI_MCP_TOOL_TIMEOUT_MS` | 所有 MCP server 的全局默认单次工具调用超时（毫秒）；优先级高于 `config.toml` 的 `[mcp] tool_timeout_ms`，但低于 `mcp.json` 中单个 server 的 `toolTimeoutMs`（默认 `60000`） | `1` 到 `2147483647` 的整数；非法值被忽略 |