fix: tighten as any usage in performanceShim and clarify fileHistory cap

- performanceShim: replace 'as any' on the onresourcetimingbufferfull getter/setter and the globalThis install guard with typed intersection casts, per the project's TS guideline. - fileHistory: clarify the MAX_SNAPSHOTS comment so it reflects that checkpointing is throttled (cap reduced from 100 to 20), not disabled.
fix: address coderabbit review feedback on PR #413
2026-06-15 21:05:51 +00:00 · 2026-05-05 13:25:35 +00:00 · 2026-05-05 13:23:35 +00:00
18 changed files with 95 additions and 662 deletions
--- a/docs/features/background-agent-selector.md
+++ b/docs/features/background-agent-selector.md
@@ -1,225 +0,0 @@
-# Background Agent Selector — 底部统一后台 Agent 切换器
-
-> Feature Flag: 无（直接启用）
-> 实现状态：完整可用
-> 依赖：`viewingAgentTaskId` / `enterTeammateView` / `exitTeammateView` 已有机制
-
-## 一、功能概述
-
-Background Agent Selector 是渲染在 PromptInput 下方的常驻状态条，列出当前所有 **backgrounded 的 local_agent 任务**（包括 `/fork` 派生的 fork agent 和 Task/AgentTool 调用 `run_in_background: true` 派生的子 agent）。用户可以用 ↑/↓ 方向键在 `main` 和各 agent 之间切换焦点，按 Enter 把 REPL 主视图替换为所选 agent 的实时 transcript，再按 Enter 选中 `main` 即可回到主对话。
-
-整个机制完全复用官方已有的 teammate transcript 查看基础设施，不引入新的视图层 / 数据流，仅新增一条 footer pill 类型。
-
-### 核心特性
-
- **统一入口**：`/fork`、Task 派生的 subagent、所有 `run_in_background: true` 的 agent 都在同一栏显示
- **就地切换**：prompt 为空时按 ↓ 溢出进入底部 selector，↑↓ 选中某行，Enter 即切主视图
- **实时状态**：每行显示 agent 类型 + 描述 + 运行时长 + 已消耗 token；running 时圆点为绿色
- **Keep-alive 视图**：agent 完成后在 `evictAfter` grace 窗口内保留一段时间，用户可回看
- **零界面侵入**：tasks 数为 0 时 selector 完全不渲染，不占屏幕高度
- **与旧 Dialog 共存**：Shift+↓ 打开的 `BackgroundTasksDialog` 原有行为保留，selector 只作为展示 + 快捷切换
-
-## 二、用户交互
-
-### 触发方式
-
-有任何 background agent 时，selector 自动出现在 `bypass permissions on` 行下方：
-
-```
-  claude-code | Opus 4.7 (1M context) | ctx:4%
-  ▶▶ bypass permissions on (shift+tab to cycle)
-
-  ○ main                                    ↑/↓ to select · Enter to view
-  ● Explore  Research src/hooks              23s · ↓ 10.9k tokens
-  ○ Explore  Research src/components         22s · ↓  9.5k tokens
-  ○ Explore  Research src/utils              21s · ↓ 13.6k tokens
-```
-
-### 键盘路由
-
-| 位置 / 状态 | 按键 | 行为 |
-|---|---|---|
-| PromptInput 非空 | ↑↓ | 光标移动 / 翻历史（不变） |
-| PromptInput 空 + 历史底部 | ↓ | 焦点下放到 selector，高亮到 `● main` |
-| Selector 聚焦（`footerSelection === 'bg_agent'`） | ↓ | 高亮下移，-1 → 0 → ... → N-1 |
-| Selector 聚焦 | ↑ | 高亮上移；在 `main` 再 ↑ → 焦点回 PromptInput |
-| Selector 聚焦 | Enter | `-1` → `exitTeammateView`；`>=0` → `enterTeammateView(agentId)`。焦点保留在 pill |
-| Selector 聚焦 | Esc | `footer:clearSelection`，焦点回 PromptInput |
-
-### 视觉规则
-
- `● main` / `● <agent>`：当前被**查看**（viewingAgentTaskId 指向）或被**光标聚焦**（pill focused 时以光标为准）的一行
- running 状态的 agent：圆点渲染为 `success` 色（绿色），与 `BackgroundTasksDialog` 状态语义对齐
- 右上角 hint 随状态变化：
-  - pill 聚焦：`↑/↓ to select · Enter to view`
-  - 已选中 running agent：`shift+↓ to manage · x to stop`
-  - 已选中 terminal agent：`shift+↓ to manage · x to clear`
-  - 未选中任何 agent：`shift+↓ to manage background agents`
-
-## 三、实现架构
-
-### 3.1 数据层：`useBackgroundAgentTasks`
-
-文件：`src/hooks/useBackgroundAgentTasks.ts`
-
-封装对 `useAppState(s => s.tasks)` 的过滤：
-
-```ts
-export function useBackgroundAgentTasks(): LocalAgentTaskState[] {
-  const tasks = useAppState(s => s.tasks)
-  return useMemo(() => {
-    const now = Date.now()
-    return Object.values(tasks)
-      .filter(isLocalAgentTask)
-      .filter(t => t.agentType !== 'main-session')
-      .filter(t => t.isBackgrounded !== false)
-      .filter(t => t.evictAfter === undefined || t.evictAfter > now)
-      .sort((a, b) => a.startTime - b.startTime)
-  }, [tasks])
-}
-```
-
-`/fork` 和 `AgentTool` 的 `run_in_background: true` 底层都走 `registerAsyncAgent → runAsyncAgentLifecycle`，最终写入同一个 `appState.tasks` Map；此 hook 是唯一数据源，Selector 和 PromptInput 的 `bgAgentList` 都消费它。
-
-### 3.2 状态层：新增两个字段
-
-文件：`src/state/AppStateStore.ts`
-
-```ts
-export type FooterItem =
-  | 'tasks' | 'tmux' | 'bagel' | 'teams' | 'bridge' | 'companion'
-  | 'bg_agent'   // ← 新增
-
-export type AppState = DeepImmutable<{
-  // ...
-  selectedBgAgentIndex: number  // -1 = main, 0..N-1 = 选中的 agent
-}>
-```
-
- `'bg_agent'` 作为 `FooterItem` 加入 footer pill 体系，享受既有的 `footer:up` / `footer:down` / `footer:openSelected` keybinding 路由
- `selectedBgAgentIndex` 记录 selector 的光标位置，与 `viewingAgentTaskId`（"正在看什么"）独立；它不可从 `viewingAgentTaskId` 派生——Enter 后光标留在 pill 继续导航，查看目标才变
-
-### 3.3 键盘路由：PromptInput footer pill 分支
-
-文件：`src/components/PromptInput/PromptInput.tsx`
-
-1. **`bg_agent` 进入 footerItems[0]**：保证 prompt ↓ 溢出时（`handleHistoryDown` → `selectFooterItem(footerItems[0])`）直接进入 selector，而不是 `tasks` 等其他 pill
-2. **`footer:up` 分支**：`bgAgentSelected` 时 `selectedBgAgentIndex > -1` 则递减；在 -1 → `selectFooterItem(null)` 退出 pill
-3. **`footer:down` 分支**：`selectedBgAgentIndex < bgAgentList.length - 1` 则递增，到底 clamp
-4. **`footer:openSelected` 分支**：index === -1 → `exitTeammateView`；否则 `enterTeammateView(bgAgentList[i].agentId)`。**不清理 pill 焦点**，光标留在 selector 上继续导航
-5. **`selectFooterItem('bg_agent')`**：入 pill 时重置 `selectedBgAgentIndex = -1`（光标落到 `main`）
-
-### 3.4 渲染层：`BackgroundAgentSelector`
-
-文件：`src/components/tasks/BackgroundAgentSelector.tsx`
-
-纯展示组件，不订阅键盘：
-
-```tsx
-const tasks = useBackgroundAgentTasks()
-const viewingId = useAppState(s => s.viewingAgentTaskId)
-const footerSelection = useAppState(s => s.footerSelection)
-const selectedBgIndex = useAppState(s => s.selectedBgAgentIndex)
-
-if (tasks.length === 0) return null
-
-const pillFocused = footerSelection === 'bg_agent'
-const highlightedId = pillFocused
-  ? (selectedBgIndex === -1 ? null : tasks[selectedBgIndex]?.agentId ?? null)
-  : (viewingId ?? null)
-```
-
-**高亮派生规则**：pill 聚焦 → 跟 `selectedBgAgentIndex`；未聚焦 → 镜像 `viewingAgentTaskId`。这样当用户通过 Shift+↓ Dialog 或 `enterTeammateView` 其它途径切换视图时，selector 也会正确反映。
-
-### 3.5 主视图切换：复用 `viewingAgentTaskId`
-
-REPL.tsx 主体仍复用原有查看逻辑：
-
-```ts
-const viewedTask = viewingAgentTaskId ? tasks[viewingAgentTaskId] : undefined
-const viewedAgentTask = ... (isLocalAgentTask(viewedTask) ? viewedTask : undefined)
-const displayedMessages = viewedAgentTask ? displayedAgentMessages : messages
-```
-
-当 `enterTeammateView(agentId)` 把 `viewingAgentTaskId` 设成某个 local_agent 的 id：
-
- `viewedAgentTask` 解析成该 agent
- `displayedMessages` 切换到 agent 的 messages
- 消息列表、spinner、unseen divider 等一整套组件自动用 agent transcript 重渲染
- 主对话流被"暂停"（并非销毁，回到 `main` 时仍在原处）
-
-`enterTeammateView` 同步负责：设 `retain: true` 阻止 eviction、清 `evictAfter`、触发 disk bootstrap 从 `agent-<id>.jsonl` 加载完整 transcript 到 `task.messages`。
-
-#### Fork agent prompt 归一化
-
-`/fork` agent 的 transcript 和普通 subagent 不同：它继承 main agent 的上下文，真实初始消息形态是：
-
-```text
-...parent messages
-assistant([...tool_use])
-user([tool_result..., text("<fork-boilerplate>...Your directive: <prompt>")])
-...fork live messages
-```
-
-这里的 prompt 文本混在 `[tool_result..., text]` 多 block user message 里。消息渲染管线会优先把这条 user message 当作 tool-result plumbing 来处理，导致 `<fork-boilerplate>` 里的用户 prompt 不稳定可见。为保证切换到 fork agent 时总能看到用户发起的 fork prompt，REPL.tsx 对 fork 视图做一次展示层归一化：
-
-1. 仅当 `viewedAgentTask.agentType === 'fork'` 时启用，不影响普通 Explore / Task subagent。
-2. 从原始 messages 中识别包含 `<fork-boilerplate>` 的 carrier message。
-3. 剥离 carrier message 里的 boilerplate text block，但保留 `tool_result` blocks，避免破坏父 assistant `tool_use` 的承接关系。
-4. 强制插入一条独立 `createUserMessage({ content: viewedAgentTask.prompt })` 作为可见用户 prompt。
-5. 插入位置优先为 boilerplate carrier 后；如果 sidechain bootstrap 还没读到 carrier，则插到最后一条 inherited `assistant tool_use` 后面，确保 prompt 接在 main 上下文之后，而不是跑到视图顶部。
-
-这个归一化只影响 UI 展示用的 `displayedAgentMessages`，不回写 `task.messages`，也不改变发送给模型的 fork transcript。
-
-### 3.6 生命周期
-
-完全复用官方既有机制：
-
- **运行中**：`isBackgroundTask()` 谓词为真，selector 列出
- **完成 / 失败 / 中止**：`completeAgentTask` / `failAgentTask` / `killAsyncAgent` 设 `status` 为 terminal
- **回访后退出**：`exitTeammateView` 调 `release(task)`——清 `retain`、清 `messages`、terminal 状态下设 `evictAfter = now + PANEL_GRACE_MS (30s)`
- **evictAfter 过期**：`useBackgroundAgentTasks` 过滤时自然剔除，selector 行消失
- **手动清除**：`stopOrDismissAgent(taskId)` 设 `evictAfter = 0`，立即消失
-
-## 四、设计决策
-
-1. **数据源单一**：`useBackgroundAgentTasks` 是唯一过滤点，PromptInput 也复用，避免过滤条件散落
-2. **pill 聚焦保留**：Enter 切视图后不松焦，让 ↑↓ 连续导航，贴近官方体验
-3. **`bg_agent` 放 footerItems[0]**：确保 ↓ 溢出直接进入 selector 而非其它 pill
-4. **selector 不订阅键盘**：所有按键路由集中在 PromptInput 的 `footer:*` 分支，避免 selector 组件和 PromptInput 双重 `useInput` 的冲突
-5. **`selectedBgAgentIndex` 存 AppState 而非局部 state**：selector 和 PromptInput 分别在两棵不同子树，需要全局字段协调；该值不能从 `viewingAgentTaskId` 派生
-6. **与 `BackgroundTasksDialog` 共存**：Shift+↓ 行为完全不变，selector 是补充快捷入口；Dialog 仍管 shell / workflow / monitor_mcp 等 selector 不显示的 task 类型
-7. **fork prompt 展示层兜底**：fork prompt 不依赖 boilerplate 自身渲染，统一在 `displayedAgentMessages` 中合成独立用户消息；普通 subagent 不走该分支，避免 prompt 重复
-
-## 五、关键 API 复用
-
-| 官方已有能力 | selector 如何使用 |
-|---|---|
-| `AppState.tasks` | 单一数据源，无需 file watcher / output JSONL 订阅 |
-| `registerAsyncAgent` | `/fork` 和 AgentTool 共用，selector 不区分来源 |
-| `enterTeammateView(id)` | Enter 时调用，负责 retain + disk bootstrap |
-| `exitTeammateView` | Enter 选中 `main` 时调用 |
-| `release(task)` + `PANEL_GRACE_MS` | 30s keep-alive，selector 自动生效 |
-| `useElapsedTime` | 每行时长显示，非 running 自动停 interval |
-| `formatTokens` (`utils/format.ts`) | token 数 1k 缩写 |
-| `footer:up` / `footer:down` / `footer:openSelected` keybinding | 键盘路由复用 Footer context |
-
-## 六、文件索引
-
-| 文件 | 职责 |
-|------|------|
-| `src/hooks/useBackgroundAgentTasks.ts` | 数据过滤 hook（backgrounded local_agent + evictAfter 过滤 + startTime 排序） |
-| `src/components/tasks/BackgroundAgentSelector.tsx` | 底部 selector UI，纯展示 |
-| `src/components/PromptInput/PromptInput.tsx` | 新增 `'bg_agent'` footer pill + 对应的 `footer:up/down/openSelected` 分支 |
-| `src/state/AppStateStore.ts` | `FooterItem` 加 `'bg_agent'`；新增 `selectedBgAgentIndex` 字段 |
-| `src/main.tsx` | `getDefaultAppState` 同步初始化 `selectedBgAgentIndex: -1` |
-| `src/screens/REPL.tsx` | 在 PromptInput + SessionBackgroundHint 之后挂载 `<BackgroundAgentSelector />`；切换 agent 主视图；对 fork transcript 做 prompt 归一化 |
-| `src/components/messages/AssistantToolUseMessage.tsx` | 新增 `defaultCollapsed?: boolean` prop，为后续详情视图默认折叠工具块预留 |
-| `src/components/messages/UserTextMessage.tsx` | 识别 `<fork-boilerplate>`，交给 fork 专用 renderer 处理 |
-| `src/components/messages/UserForkBoilerplateMessage.tsx` | 将 fork boilerplate text 折叠为纯用户 prompt；作为 transcript 中原位渲染的兼容路径 |
-
-## 七、已知限制
-
- `Date.now()` 在 `useBackgroundAgentTasks` 的 useMemo 里冻结于 `[tasks]` 触发时：若长时间没有新 task 变更事件，某个 terminal agent 的 grace 期过期后不会立即从 selector 消失，要等下一次 tasks 变化才刷新。在典型使用（主对话一直在产生消息）下感知不到，暂不额外加 interval。
- Selector 当前不处理 Shell Task / Workflow / Monitor MCP 等类型——这些仍走 `BackgroundTasksDialog`（Shift+↓）管理。
- `AssistantToolUseMessage` 的 `defaultCollapsed` prop 目前无调用方传值，保留作为后续"agent 详情视图内工具块默认折叠"扩展点。
--- a/scripts/dev.ts
+++ b/scripts/dev.ts
@@ -14,11 +14,20 @@ const __dirname = dirname(__filename)
 const projectRoot = join(__dirname, '..')
 const cliPath = join(projectRoot, 'src/entrypoints/cli.tsx')

+// React production mode — prevents 6,889+ _debugStack Error objects
+// (12MB) from accumulating during long-running sessions.
+// Opt-in via CLAUDE_CODE_FORCE_NODE_ENV=production for dev sessions that
+// need the memory optimization. Default keeps NODE_ENV='development' so
+// dev-only diagnostics (DevBar, doctorDiagnostic, AutoUpdater dev branches,
+// etc.) continue to work.
+const forcedNodeEnv =
+  process.env.CLAUDE_CODE_FORCE_NODE_ENV ??
+  process.env.NODE_ENV ??
+  'development'
+
 const defines = {
  ...getMacroDefines(),
-  // React production mode — prevents 6,889+ _debugStack Error objects
-  // (12MB) from accumulating during long-running sessions.
-  'process.env.NODE_ENV': JSON.stringify('production'),
+  'process.env.NODE_ENV': JSON.stringify(forcedNodeEnv),
 }

 const defineArgs = Object.entries(defines).flatMap(([k, v]) => [
--- a/src/commands/fork/fork.tsx
+++ b/src/commands/fork/fork.tsx
@@ -43,12 +43,8 @@ export async function call(
    // Omitting subagent_type triggers implicit fork.
    const input = {
      prompt: directive,
-      fork: true, // 触发 AgentTool 的 fork 路径：继承父会话上下文 + system prompt + 模型
      run_in_background: true, // fork always runs async
-      // description 只显示在底部 selector / BackgroundTasksDialog，保持简短标签
-      // 即可；用户输入的 prompt 会作为第一条用户消息呈现在主视图里，这里不要
-      // 重复显示。
-      description: 'forked from main',
+      description: `Fork: ${directive.slice(0, 30)}${directive.length > 30 ? '...' : ''}`,
    };

    // Call AgentTool with proper parameters:
--- a/src/components/PromptInput/PromptInput.tsx
+++ b/src/components/PromptInput/PromptInput.tsx
@@ -26,7 +26,6 @@ import { useSetPromptOverlayDialog } from '../../context/promptOverlayContext.js
 import { formatImageRef, formatPastedTextRef, getPastedTextRefNumLines, parseReferences } from '../../history.js';
 import type { VerificationStatus } from '../../hooks/useApiKeyVerification.js';
 import { type HistoryMode, useArrowKeyHistory } from '../../hooks/useArrowKeyHistory.js';
-import { useBackgroundAgentTasks } from '../../hooks/useBackgroundAgentTasks.js';
 import { useDoublePress } from '../../hooks/useDoublePress.js';
 import { useHistorySearch } from '../../hooks/useHistorySearch.js';
 import type { IDESelection } from '../../hooks/useIdeSelection.js';
@@ -416,16 +415,6 @@ function PromptInput({
  // First ↓ selects the pill, second ↓ moves to row 0. Prevents double-select
  // of pill + row when both bg tasks (pill) and forked agents (rows) are visible.
  const coordinatorTaskIndex = useAppState(s => s.coordinatorTaskIndex);
-  const selectedBgAgentIndex = useAppState(s => s.selectedBgAgentIndex);
-  const setSelectedBgAgentIndex = useCallback(
-    (v: number | ((prev: number) => number)) =>
-      setAppState(prev => {
-        const next = typeof v === 'function' ? v(prev.selectedBgAgentIndex) : v;
-        if (next === prev.selectedBgAgentIndex) return prev;
-        return { ...prev, selectedBgAgentIndex: next };
-      }),
-    [setAppState],
-  );
  const setCoordinatorTaskIndex = useCallback(
    (v: number | ((prev: number) => number)) =>
      setAppState(prev => {
@@ -512,13 +501,10 @@ function PromptInput({
    (runningTaskCount > 0 || (process.env.USER_TYPE === 'ant' && coordinatorTaskCount > 0)) &&
    !shouldHideTasksFooter(tasks, showSpinnerTree);
  const teamsFooterVisible = cachedTeams.length > 0;
-  const bgAgentList = useBackgroundAgentTasks();
-  const bgAgentFooterVisible = bgAgentList.length > 0;

  const footerItems = useMemo(
    () =>
      [
-        bgAgentFooterVisible && 'bg_agent',
        tasksFooterVisible && 'tasks',
        tmuxFooterVisible && 'tmux',
        bagelFooterVisible && 'bagel',
@@ -527,7 +513,6 @@ function PromptInput({
        companionFooterVisible && 'companion',
      ].filter(Boolean) as FooterItem[],
    [
-      bgAgentFooterVisible,
      tasksFooterVisible,
      tmuxFooterVisible,
      bagelFooterVisible,
@@ -555,7 +540,6 @@ function PromptInput({
  const _bagelSelected = footerItemSelected === 'bagel';
  const teamsSelected = footerItemSelected === 'teams';
  const bridgeSelected = footerItemSelected === 'bridge';
-  const bgAgentSelected = footerItemSelected === 'bg_agent';

  function selectFooterItem(item: FooterItem | null): void {
    setAppState(prev => (prev.footerSelection === item ? prev : { ...prev, footerSelection: item }));
@@ -563,9 +547,6 @@ function PromptInput({
      setTeammateFooterIndex(0);
      setCoordinatorTaskIndex(minCoordinatorIndex);
    }
-    if (item === 'bg_agent') {
-      setSelectedBgAgentIndex(-1);
-    }
  }

  // delta: +1 = down/right, -1 = up/left. Returns true if nav happened
@@ -1827,15 +1808,6 @@ function PromptInput({
  useKeybindings(
    {
      'footer:up': () => {
-        // ↑ in bg_agent pill: move selection up (-1 = main). At -1, leave pill.
-        if (bgAgentSelected) {
-          if (selectedBgAgentIndex > -1) {
-            setSelectedBgAgentIndex(prev => prev - 1);
-          } else {
-            selectFooterItem(null);
-          }
-          return;
-        }
        // ↑ scrolls within the coordinator task list before leaving the pill
        if (
          tasksSelected &&
@@ -1849,13 +1821,6 @@ function PromptInput({
        navigateFooter(-1, true);
      },
      'footer:down': () => {
-        // ↓ in bg_agent pill: move selection down through agents. Clamp at last.
-        if (bgAgentSelected) {
-          if (selectedBgAgentIndex < bgAgentList.length - 1) {
-            setSelectedBgAgentIndex(prev => prev + 1);
-          }
-          return;
-        }
        // ↓ scrolls within the coordinator task list, never leaves the pill
        if (tasksSelected && process.env.USER_TYPE === 'ant' && coordinatorTaskCount > 0) {
          if (coordinatorTaskIndex < coordinatorTaskCount - 1) {
@@ -1941,15 +1906,6 @@ function PromptInput({
            setShowBridgeDialog(true);
            selectFooterItem(null);
            break;
-          case 'bg_agent':
-            if (selectedBgAgentIndex === -1) {
-              exitTeammateView(setAppState);
-            } else {
-              const picked = bgAgentList[selectedBgAgentIndex];
-              if (picked) enterTeammateView(picked.agentId, setAppState);
-            }
-            // Keep the pill focused so ↑/↓ continue to work after Enter.
-            break;
        }
      },
      'footer:clearSelection': () => {
--- a/src/components/messages/AssistantToolUseMessage.tsx
+++ b/src/components/messages/AssistantToolUseMessage.tsx
@@ -30,7 +30,6 @@ type Props = {
  inProgressToolCallCount?: number;
  lookups: ReturnType<typeof buildMessageLookups>;
  isTranscriptMode?: boolean;
-  defaultCollapsed?: boolean;
 };

 export function AssistantToolUseMessage({
@@ -46,7 +45,6 @@ export function AssistantToolUseMessage({
  inProgressToolCallCount,
  lookups,
  isTranscriptMode,
-  defaultCollapsed,
 }: Props): React.ReactNode {
  const terminalSize = useTerminalSize();
  const [theme] = useTheme();
@@ -169,7 +167,6 @@ export function AssistantToolUseMessage({
        </Box>
        {!isResolved &&
          !isQueued &&
-          !defaultCollapsed &&
          (isClassifierChecking ? (
            <MessageResponse height={1}>
              <Text dimColor>
--- a/src/components/messages/UserForkBoilerplateMessage.tsx
+++ b/src/components/messages/UserForkBoilerplateMessage.tsx
@@ -3,31 +3,28 @@
 */
 import type { TextBlockParam } from '@anthropic-ai/sdk/resources/index.mjs';
 import * as React from 'react';
-import { FORK_BOILERPLATE_TAG, FORK_DIRECTIVE_PREFIX } from '../../constants/xml.js';
+import { Box, Text } from '@anthropic/ink';
 import { extractTag } from '../../utils/messages.js';
-import { UserPromptMessage } from './UserPromptMessage.js';

 type Props = {
  addMargin: boolean;
  param: TextBlockParam;
-  isTranscriptMode?: boolean;
-  timestamp?: string;
 };

-export function UserForkBoilerplateMessage({ param, addMargin, isTranscriptMode, timestamp }: Props): React.ReactNode {
-  if (!extractTag(param.text, FORK_BOILERPLATE_TAG)) return null;
-  const closeTag = `</${FORK_BOILERPLATE_TAG}>`;
-  const afterTag = param.text.slice(param.text.indexOf(closeTag) + closeTag.length).trimStart();
-  const userPrompt = afterTag.startsWith(FORK_DIRECTIVE_PREFIX)
-    ? afterTag.slice(FORK_DIRECTIVE_PREFIX.length)
-    : afterTag;
+export function UserForkBoilerplateMessage({ param, addMargin }: Props): React.ReactNode {
+  const text = param.text;
+  const extracted = extractTag(text, 'fork-boilerplate');
+  if (!extracted) {
+    return null;
+  }
+
+  const firstLine = extracted.trim().split('\n')[0] ?? '';
+  const preview = firstLine.length > 80 ? firstLine.slice(0, 77) + '...' : firstLine;

  return (
-    <UserPromptMessage
-      addMargin={addMargin}
-      param={{ type: 'text', text: userPrompt }}
-      isTranscriptMode={isTranscriptMode}
-      timestamp={timestamp}
-    />
+    <Box flexDirection="row" marginTop={addMargin ? 1 : 0}>
+      <Text dimColor>[fork] </Text>
+      <Text>{preview}</Text>
+    </Box>
  );
 }
--- a/src/components/messages/UserTextMessage.tsx
+++ b/src/components/messages/UserTextMessage.tsx
@@ -4,7 +4,6 @@ import * as React from 'react';
 import { NO_CONTENT_MESSAGE } from '../../constants/messages.js';
 import {
  COMMAND_MESSAGE_TAG,
-  FORK_BOILERPLATE_TAG,
  LOCAL_COMMAND_CAVEAT_TAG,
  TASK_NOTIFICATION_TAG,
  TEAMMATE_MESSAGE_TAG,
@@ -125,21 +124,16 @@ export function UserTextMessage({
  }

  // Fork child's first message: collapse the rules/format boilerplate, show
-  // only the user prompt. Independent of FORK_SUBAGENT flag — the fork agent
-  // transcript always needs to render the prompt as a normal user bubble.
-  if (param.text.includes(`<${FORK_BOILERPLATE_TAG}>`)) {
-    /* eslint-disable @typescript-eslint/no-require-imports */
-    const { UserForkBoilerplateMessage } =
-      require('./UserForkBoilerplateMessage.js') as typeof import('./UserForkBoilerplateMessage.js');
-    /* eslint-enable @typescript-eslint/no-require-imports */
-    return (
-      <UserForkBoilerplateMessage
-        addMargin={addMargin}
-        param={param}
-        isTranscriptMode={isTranscriptMode}
-        timestamp={timestamp}
-      />
-    );
+  // only the directive. FORK_BOILERPLATE_TAG is inlined so the import doesn't
+  // ship in external builds where feature('FORK_SUBAGENT') is false.
+  if (feature('FORK_SUBAGENT')) {
+    if (param.text.includes('<fork-boilerplate>')) {
+      /* eslint-disable @typescript-eslint/no-require-imports */
+      const { UserForkBoilerplateMessage } =
+        require('./UserForkBoilerplateMessage.js') as typeof import('./UserForkBoilerplateMessage.js');
+      /* eslint-enable @typescript-eslint/no-require-imports */
+      return <UserForkBoilerplateMessage addMargin={addMargin} param={param} />;
+    }
  }

  // Cross-session UDS message (from another Claude session's SendMessage).
--- a/src/components/tasks/BackgroundAgentSelector.tsx
+++ b/src/components/tasks/BackgroundAgentSelector.tsx
@@ -1,63 +0,0 @@
-import { Box, Text } from '@anthropic/ink';
-import { useBackgroundAgentTasks } from '../../hooks/useBackgroundAgentTasks.js';
-import { useElapsedTime } from '../../hooks/useElapsedTime.js';
-import { useAppState } from '../../state/AppState.js';
-import type { LocalAgentTaskState } from '../../tasks/LocalAgentTask/LocalAgentTask.js';
-import { formatTokens } from '../../utils/format.js';
-
-function AgentRow({ task, selected }: { task: LocalAgentTaskState; selected: boolean }) {
-  const elapsed = useElapsedTime(task.startTime, task.status === 'running');
-  const tokens = task.progress?.tokenCount ?? 0;
-  const isRunning = task.status === 'running';
-  return (
-    <Box flexDirection="row" width="100%" justifyContent="space-between">
-      <Box flexDirection="row" flexShrink={1}>
-        <Text color={isRunning ? 'success' : undefined}>{selected ? '● ' : '○ '}</Text>
-        <Text bold={selected} wrap="truncate-end">
-          {task.agentType} <Text dimColor>{task.description}</Text>
-        </Text>
-      </Box>
-      <Box flexShrink={0}>
-        <Text dimColor>
-          {elapsed} · ↓ {formatTokens(tokens)} tokens
-        </Text>
-      </Box>
-    </Box>
-  );
-}
-
-function getHint(pillFocused: boolean, viewedTask: LocalAgentTaskState | null): string {
-  if (pillFocused) return '↑/↓ to select · Enter to view';
-  if (!viewedTask) return 'shift+↓ to manage background agents';
-  return viewedTask.status === 'running' ? 'shift+↓ to manage · x to stop' : 'shift+↓ to manage · x to clear';
-}
-
-export function BackgroundAgentSelector(): React.ReactNode {
-  const tasks = useBackgroundAgentTasks();
-  const viewingId = useAppState(s => s.viewingAgentTaskId);
-  const footerSelection = useAppState(s => s.footerSelection);
-  const selectedBgIndex = useAppState(s => s.selectedBgAgentIndex);
-
-  if (tasks.length === 0) return null;
-
-  const pillFocused = footerSelection === 'bg_agent';
-  const highlightedId = pillFocused
-    ? selectedBgIndex === -1
-      ? null
-      : (tasks[selectedBgIndex]?.agentId ?? null)
-    : (viewingId ?? null);
-  const mainHighlighted = pillFocused ? selectedBgIndex === -1 : viewingId === undefined;
-  const viewedTask = viewingId ? (tasks.find(t => t.agentId === viewingId) ?? null) : null;
-
-  return (
-    <Box flexDirection="column" width="100%">
-      <Box flexDirection="row" width="100%" justifyContent="space-between">
-        <Text bold={mainHighlighted}>{mainHighlighted ? '● ' : '○ '}main</Text>
-        <Text dimColor>{getHint(pillFocused, viewedTask)}</Text>
-      </Box>
-      {tasks.map(task => (
-        <AgentRow key={task.agentId} task={task} selected={task.agentId === highlightedId} />
-      ))}
-    </Box>
-  );
-}
--- a/src/hooks/useBackgroundAgentTasks.ts
+++ b/src/hooks/useBackgroundAgentTasks.ts
@@ -1,19 +0,0 @@
-import { useMemo } from 'react'
-import { useAppState } from '../state/AppState.js'
-import {
-  isLocalAgentTask,
-  type LocalAgentTaskState,
-} from '../tasks/LocalAgentTask/LocalAgentTask.js'
-
-export function useBackgroundAgentTasks(): LocalAgentTaskState[] {
-  const tasks = useAppState(s => s.tasks)
-  return useMemo(() => {
-    const now = Date.now()
-    return Object.values(tasks)
-      .filter(isLocalAgentTask)
-      .filter(t => t.agentType !== 'main-session')
-      .filter(t => t.isBackgrounded !== false)
-      .filter(t => t.evictAfter === undefined || t.evictAfter > now)
-      .sort((a, b) => a.startTime - b.startTime)
-  }, [tasks])
-}
--- a/src/main.tsx
+++ b/src/main.tsx
@@ -3485,7 +3485,6 @@ async function run(): Promise<CommanderCommand> {
            : 'none',
        showTeammateMessagePreview: isAgentSwarmsEnabled() ? false : undefined,
        selectedIPAgentIndex: -1,
-        selectedBgAgentIndex: -1,
        coordinatorTaskIndex: -1,
        viewSelectionMode: 'none',
        footerSelection: null,
--- a/src/screens/REPL.tsx
+++ b/src/screens/REPL.tsx
@@ -244,14 +244,7 @@ import {
  formatCommandInputTags,
 } from '../utils/messages.js';
 import { generateSessionTitle } from '../utils/sessionTitle.js';
-import {
-  BASH_INPUT_TAG,
-  COMMAND_MESSAGE_TAG,
-  COMMAND_NAME_TAG,
-  FORK_BOILERPLATE_TAG,
-  LOCAL_COMMAND_STDOUT_TAG,
-} from '../constants/xml.js';
-import { FORK_SUBAGENT_TYPE } from '@claude-code-best/builtin-tools/tools/AgentTool/forkSubagent.js';
+import { BASH_INPUT_TAG, COMMAND_MESSAGE_TAG, COMMAND_NAME_TAG, LOCAL_COMMAND_STDOUT_TAG } from '../constants/xml.js';
 import { escapeXml } from '../utils/xml.js';
 import type { ThinkingConfig } from '../utils/thinking.js';
 import { gracefulShutdownSync } from '../utils/gracefulShutdown.js';
@@ -343,7 +336,6 @@ import {
 import { isBgSession, updateSessionName, updateSessionActivity } from '../utils/concurrentSessions.js';
 import { isInProcessTeammateTask, type InProcessTeammateTaskState } from '../tasks/InProcessTeammateTask/types.js';
 import { restoreRemoteAgentTasks } from '../tasks/RemoteAgentTask/RemoteAgentTask.js';
-import { BackgroundAgentSelector } from '../components/tasks/BackgroundAgentSelector.js';
 import { useInboxPoller } from '../hooks/useInboxPoller.js';
 // Dead code elimination: conditional import for loop mode
 /* eslint-disable @typescript-eslint/no-require-imports */
@@ -808,21 +800,6 @@ export type Props = {

 export type Screen = 'prompt' | 'transcript';

-// Boilerplate carrier lives in a mixed user message ([tool_result..., text])
-// that AgentTool/forkSubagent.buildForkedMessages emits as the fork child's
-// first user turn. The text block wraps <FORK_BOILERPLATE_TAG>...</..> + the
-// user prompt; tool_result siblings keep the parent's tool calls closed.
-const FORK_BOILERPLATE_OPEN_TAG = `<${FORK_BOILERPLATE_TAG}>`;
-
-function isForkBoilerplateTextBlock(block: { type: string; text?: string }): boolean {
-  return block.type === 'text' && typeof block.text === 'string' && block.text.includes(FORK_BOILERPLATE_OPEN_TAG);
-}
-
-function isForkBoilerplateMessage(message: MessageType): boolean {
-  if (message.type !== 'user' || !Array.isArray(message.message?.content)) return false;
-  return message.message.content.some(isForkBoilerplateTextBlock);
-}
-
 export function REPL({
  commands: initialCommands,
  debug,
@@ -4960,7 +4937,7 @@ export function REPL({
  useMailboxBridge({ isLoading, onSubmitMessage: handleIncomingPrompt });
  useMasterMonitor();
  useSlaveNotifications();
-  const _pipeIpcState = useAppState(s => getPipeIpc(s as any));
+  const _pipeIpcState = useAppState(s => getPipeIpc(s));

  usePipePermissionForward({ store, tools, setMessages, setToolUseConfirmQueue, getToolUseContext, mainLoopModel });
  usePipeMuteSync({ setToolUseConfirmQueue });
@@ -5571,72 +5548,8 @@ export function REPL({
  const usesSyncMessages = showStreamingText || !isLoading;
  // When viewing an agent, never fall through to leader — empty until
  // bootstrap/stream fills. Closes the see-leader-type-agent footgun.
-  const rawAgentMessages = viewedAgentTask?.messages;
-  // Fork sidechain encodes the user prompt inside a mixed user message alongside
-  // tool_result blocks; surface the prompt as a standalone bubble and strip the
-  // boilerplate text from its original carrier while preserving tool_results.
-  const displayedAgentMessages = useMemo(() => {
-    if (!viewedAgentTask) return undefined;
-    const agentMessages = rawAgentMessages ?? [];
-    if (
-      !isLocalAgentTask(viewedAgentTask) ||
-      viewedAgentTask.agentType !== FORK_SUBAGENT_TYPE ||
-      !viewedAgentTask.prompt
-    ) {
-      return agentMessages;
-    }
-    // Single pass: locate boilerplate carrier, check whether the prompt text is
-    // already present elsewhere, and find the fallback insertion point (after
-    // the last parent assistant tool_use).
-    const trimmedPrompt = viewedAgentTask.prompt.trim();
-    let boilerplateIndex = -1;
-    let lastAssistantToolUseIndex = -1;
-    let promptAlreadyRendered = false;
-    for (let i = 0; i < agentMessages.length; i++) {
-      const m = agentMessages[i]!;
-      if (m.type === 'user' && Array.isArray(m.message?.content)) {
-        const hasBoilerplate = m.message.content.some(isForkBoilerplateTextBlock);
-        if (hasBoilerplate) {
-          boilerplateIndex = i;
-        } else if (!promptAlreadyRendered) {
-          const firstText = m.message.content.find(b => b.type === 'text' && typeof b.text === 'string') as
-            | { type: 'text'; text: string }
-            | undefined;
-          if (firstText && firstText.text.trim() === trimmedPrompt) promptAlreadyRendered = true;
-        }
-        continue;
-      }
-      if (m.type === 'assistant' && Array.isArray(m.message?.content)) {
-        if (m.message.content.some(b => b.type === 'tool_use')) lastAssistantToolUseIndex = i;
-      }
-    }
-
-    const stripped =
-      boilerplateIndex === -1
-        ? agentMessages
-        : agentMessages.map((m, i) => {
-            if (i !== boilerplateIndex) return m;
-            if (!Array.isArray(m.message?.content)) return m;
-            return {
-              ...m,
-              message: {
-                ...m.message,
-                content: m.message.content.filter(b => !isForkBoilerplateTextBlock(b)),
-              },
-            };
-          });
-
-    if (promptAlreadyRendered) return stripped;
-
-    const insertAt = boilerplateIndex !== -1 ? boilerplateIndex + 1 : lastAssistantToolUseIndex + 1;
-    const synthetic = createUserMessage({
-      content: viewedAgentTask.prompt,
-      timestamp: new Date(viewedAgentTask.startTime).toISOString(),
-    });
-    return [...stripped.slice(0, insertAt), synthetic, ...stripped.slice(insertAt)];
-  }, [viewedAgentTask, rawAgentMessages]);
  const displayedMessages = viewedAgentTask
-    ? (displayedAgentMessages ?? [])
+    ? (viewedAgentTask.messages ?? [])
    : usesSyncMessages
      ? messages
      : deferredMessages;
@@ -6373,7 +6286,6 @@ export function REPL({
                      voiceInterimRange={voice.interimRange}
                    />
                    <SessionBackgroundHint onBackgroundSession={handleBackgroundSession} isLoading={isLoading} />
-                    <BackgroundAgentSelector />
                  </>
                )}
                {cursor && (
--- a/src/services/api/claude.ts
+++ b/src/services/api/claude.ts
@@ -509,30 +509,10 @@ export function getAPIMetadata() {
    }
  }

-  const deviceId = getOrCreateUserID()
-
-  // Third-party API providers (DeepSeek, etc.) validate user_id against
-  // ^[a-zA-Z0-9_-]+$ which rejects JSON strings containing {, ", :, etc.
-  // When using a non-Anthropic base URL, send only the device_id (hex string).
-  const baseUrl = process.env.ANTHROPIC_BASE_URL
-  const isThirdParty =
-    baseUrl &&
-    (() => {
-      try {
-        return new URL(baseUrl).host !== 'api.anthropic.com'
-      } catch {
-        return false
-      }
-    })()
-
-  if (isThirdParty) {
-    return { user_id: deviceId }
-  }
-
  return {
    user_id: jsonStringify({
      ...extra,
-      device_id: deviceId,
+      device_id: getOrCreateUserID(),
      // Only include OAuth account UUID when actively using OAuth authentication
      account_uuid: getOauthAccountInfo()?.accountUuid ?? '',
      session_id: getSessionId(),
--- a/src/services/api/gemini/index.ts
+++ b/src/services/api/gemini/index.ts
@@ -6,7 +6,7 @@ import type {
  StreamEvent,
  SystemAPIErrorMessage,
 } from '../../../types/message.js'
-import { type Tools } from '../../../Tool.js'
+import type { Tools } from 'src/Tool.js'
 import { toolToAPISchema } from '../../../utils/api.js'
 import { logForDebugging } from '../../../utils/debug.js'
 import {
--- a/src/services/mcp/client.ts
+++ b/src/services/mcp/client.ts
@@ -74,10 +74,7 @@ import {
 } from '../../utils/errors.js'
 import { getMCPUserAgent } from '../../utils/http.js'
 import { maybeNotifyIDEConnected } from '../../utils/ide.js'
-import {
-  type ImageLimits,
-  maybeResizeAndDownsampleImageBuffer,
-} from '../../utils/imageResizer.js'
+import { maybeResizeAndDownsampleImageBuffer } from '../../utils/imageResizer.js'
 import { logMCPDebug, logMCPError } from '../../utils/log.js'
 import {
  getBinaryBlobSavedMessage,
@@ -105,7 +102,6 @@ import {
  isPersistError,
  persistToolResult,
 } from '../../utils/toolResultStorage.js'
-import { checkStatsigFeatureGate_CACHED_MAY_BE_STALE } from '../analytics/growthbook.js'
 import {
  type AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS,
  logEvent,
@@ -2490,23 +2486,15 @@ export function prefetchAllMcpResources(
 export async function transformResultContent(
  resultContent: PromptMessage['content'],
  serverName: string,
-  limits?: ImageLimits,
-  includeMeta = false,
 ): Promise<Array<ContentBlockParam>> {
  switch (resultContent.type) {
-    case 'text': {
-      const block: ContentBlockParam = {
-        type: 'text',
-        text: resultContent.text,
-      }
-      if (includeMeta) {
-        const meta = resultContent._meta
-        if (meta) {
-          ;(block as { _meta?: unknown })._meta = meta
-        }
-      }
-      return [block]
-    }
+    case 'text':
+      return [
+        {
+          type: 'text',
+          text: resultContent.text,
+        },
+      ]
    case 'audio': {
      const audioData = resultContent as {
        type: 'audio'
@@ -2528,7 +2516,6 @@ export async function transformResultContent(
        imageBuffer,
        imageBuffer.length,
        ext,
-        limits,
      )
      return [
        {
@@ -2564,7 +2551,6 @@ export async function transformResultContent(
            imageBuffer,
            imageBuffer.length,
            ext,
-            limits,
          )
          const content: MessageParam['content'] = []
          if (prefix) {
@@ -2685,7 +2671,6 @@ export async function transformMCPResult(
  result: unknown,
  tool: string, // Tool name for validation (e.g., "search")
  name: string, // Server name for transformation (e.g., "slack")
-  limits?: ImageLimits, // Image processing limits, plumbed to transformResultContent
 ): Promise<TransformedMCPResult> {
  if (result && typeof result === 'object') {
    if ('toolResult' in result) {
@@ -2709,9 +2694,7 @@ export async function transformMCPResult(
    if ('content' in result && Array.isArray(result.content)) {
      const transformedContent = (
        await Promise.all(
-          result.content.map(item =>
-            transformResultContent(item, name, limits, true),
-          ),
+          result.content.map(item => transformResultContent(item, name)),
        )
      ).flat()
      return {
@@ -2746,15 +2729,8 @@ export async function processMCPResult(
  result: unknown,
  tool: string, // Tool name for validation (e.g., "search")
  name: string, // Server name for IDE check and transformation (e.g., "slack")
-  limits?: ImageLimits, // Image processing limits, plumbed to transformMCPResult
-  skipLargeOutput = false, // If true, skip large-output handling for non-image content
 ): Promise<MCPToolResult> {
-  const { content, type, schema } = await transformMCPResult(
-    result,
-    tool,
-    name,
-    limits,
-  )
+  const { content, type, schema } = await transformMCPResult(result, tool, name)

  // IDE tools are not going to the model directly, so we don't need to
  // handle large output.
@@ -2762,12 +2738,6 @@ export async function processMCPResult(
    return content
  }

-  // Caller opted out of large-output handling (e.g., result already truncated
-  // upstream); only continue if the content has images that may need handling.
-  if (skipLargeOutput && !contentContainsImages(content)) {
-    return content
-  }
-
  // Check if content needs truncation (i.e., is too large)
  if (!(await mcpContentNeedsTruncation(content))) {
    return content
@@ -2805,15 +2775,9 @@ export async function processMCPResult(
  // Generate a unique ID for the persisted file (server__tool-timestamp)
  const timestamp = Date.now()
  const persistId = `mcp-${normalizeNameForMCP(name)}-${normalizeNameForMCP(tool)}-${timestamp}`
-  // When the large-string format gate is on, unwrap a single bare text block
-  // (no annotations, no _meta) into raw text so the model gets plain text in
-  // the persisted file instead of a JSON-wrapped block. The `_meta` check is
-  // why transformResultContent preserves _meta on text blocks.
-  const unwrappedText = unwrapSingleTextBlock(content)
+  // Convert to string for persistence (persistToolResult expects string or specific block types)
  const contentStr =
-    typeof content === 'string'
-      ? content
-      : (unwrappedText ?? jsonStringify(content, null, 2))
+    typeof content === 'string' ? content : jsonStringify(content, null, 2)
  const persistResult = await persistToolResult(contentStr, persistId)

  if (isPersistError(persistResult)) {
@@ -2834,10 +2798,7 @@ export async function processMCPResult(
    persistedSizeChars: persistResult.originalSize,
  } as AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS)

-  const formatDescription =
-    unwrappedText !== undefined
-      ? getFormatDescription('toolResult')
-      : getFormatDescription(type, schema)
+  const formatDescription = getFormatDescription(type, schema)
  return getLargeOutputInstructions(
    persistResult.filepath,
    persistResult.originalSize,
@@ -2845,39 +2806,6 @@ export async function processMCPResult(
  )
 }

-/**
- * Returns true when the large-string output format is enabled (matches
- * binary's `sf8()`). When enabled, processMCPResult unwraps a single bare
- * text block to raw text for persistence instead of JSON-wrapping it.
- *
- * Gating sources, in order:
- *   1. MCP_TRUNCATION_PROMPT_OVERRIDE env var (anything except "legacy" enables)
- *   2. Statsig gate `tengu_mcp_subagent_prompt`
- */
-function isLargeStringFormatEnabled(): boolean {
-  const override = process.env.MCP_TRUNCATION_PROMPT_OVERRIDE
-  if (override) return override !== 'legacy'
-  return checkStatsigFeatureGate_CACHED_MAY_BE_STALE(
-    'tengu_mcp_subagent_prompt',
-  )
-}
-
-/**
- * Unwraps a single bare text content block to its raw text when the
- * large-string format gate is on. Returns undefined when the gate is off,
- * the content is not an array, the array doesn't contain exactly one text
- * block, or the block carries annotations or _meta. Matches binary mg5's
- * `M=...` computation.
- */
-function unwrapSingleTextBlock(content: MCPToolResult): string | undefined {
-  if (!isLargeStringFormatEnabled()) return undefined
-  if (!Array.isArray(content) || content.length !== 1) return undefined
-  const block = content[0]
-  if (!block || block.type !== 'text') return undefined
-  if ('annotations' in block || '_meta' in block) return undefined
-  return block.text
-}
-
 /**
 * Call an MCP tool, handling UrlElicitationRequiredError (-32042) by
 * displaying the URL elicitation to the user, waiting for the completion
@@ -2899,8 +2827,6 @@ export async function callMCPToolWithUrlElicitationRetry({
  signal,
  setAppState,
  onProgress,
-  imageLimits,
-  hasResultSizeAnnotation = false,
  callToolFn = callMCPTool,
  handleElicitation,
 }: {
@@ -2912,8 +2838,6 @@ export async function callMCPToolWithUrlElicitationRetry({
  signal: AbortSignal
  setAppState: (f: (prev: AppState) => AppState) => void
  onProgress?: (data: MCPProgress) => void
-  imageLimits?: ImageLimits
-  hasResultSizeAnnotation?: boolean
  /** Injectable for testing. Defaults to callMCPTool. */
  callToolFn?: (opts: {
    client: ConnectedMCPServer
@@ -2922,8 +2846,6 @@ export async function callMCPToolWithUrlElicitationRetry({
    meta?: Record<string, unknown>
    signal: AbortSignal
    onProgress?: (data: MCPProgress) => void
-    imageLimits?: ImageLimits
-    hasResultSizeAnnotation?: boolean
  }) => Promise<MCPToolCallResult>
  /** Handler for URL elicitations when no hook handles them.
   * In print/SDK mode, delegates to structuredIO. In REPL, falls back to queue. */
@@ -2943,8 +2865,6 @@ export async function callMCPToolWithUrlElicitationRetry({
        meta,
        signal,
        onProgress,
-        imageLimits,
-        hasResultSizeAnnotation,
      })
    } catch (error) {
      // The MCP SDK's Protocol creates plain McpError (not UrlElicitationRequiredError)
@@ -3121,8 +3041,6 @@ async function callMCPTool({
  meta,
  signal,
  onProgress,
-  imageLimits,
-  hasResultSizeAnnotation = false,
 }: {
  client: ConnectedMCPServer
  tool: string
@@ -3130,8 +3048,6 @@ async function callMCPTool({
  meta?: Record<string, unknown>
  signal: AbortSignal
  onProgress?: (data: MCPProgress) => void
-  imageLimits?: ImageLimits
-  hasResultSizeAnnotation?: boolean
 }): Promise<{
  content: MCPToolResult
  _meta?: Record<string, unknown>
@@ -3260,13 +3176,7 @@ async function callMCPTool({
      })
    }

-    const content = await processMCPResult(
-      result,
-      tool,
-      name,
-      imageLimits,
-      hasResultSizeAnnotation,
-    )
+    const content = await processMCPResult(result, tool, name)
    return {
      content,
      _meta: result._meta as Record<string, unknown> | undefined,
--- a/src/state/AppStateStore.ts
+++ b/src/state/AppStateStore.ts
@@ -85,7 +85,6 @@ export type FooterItem =
  | 'teams'
  | 'bridge'
  | 'companion'
-  | 'bg_agent'

 export type AppState = DeepImmutable<{
  settings: SettingsJson
@@ -98,9 +97,6 @@ export type AppState = DeepImmutable<{
  // Optional - only present when ENABLE_AGENT_SWARMS is true (for dead code elimination)
  showTeammateMessagePreview?: boolean
  selectedIPAgentIndex: number
-  // Selection index for the bottom BackgroundAgentSelector.
-  // -1 = main, 0..N-1 = index into useBackgroundAgentTasks().
-  selectedBgAgentIndex: number
  // CoordinatorTaskPanel selection: -1 = pill, 0 = main, 1..N = agent rows.
  // AppState (not local) so the panel can read it directly without prop-drilling
  // through PromptInput → PromptInputFooter.
@@ -481,7 +477,6 @@ export function getDefaultAppState(): AppState {
    isBriefOnly: false,
    showTeammateMessagePreview: false,
    selectedIPAgentIndex: -1,
-    selectedBgAgentIndex: -1,
    coordinatorTaskIndex: -1,
    viewSelectionMode: 'none',
    footerSelection: null,
--- a/src/utils/fileHistory.ts
+++ b/src/utils/fileHistory.ts
@@ -51,8 +51,9 @@ export type FileHistoryState = {
  snapshotSequence: number
 }

-// Disabled: file checkpointing causes unbounded memory growth (100 snapshots × full file backups).
-// See heap snapshot analysis — re-enable only after switching to incremental diffs.
+// Throttled: file checkpointing remains enabled (gated by fileHistoryEnabled())
+// but capped to mitigate unbounded memory growth (full file backups x N snapshots).
+// See heap snapshot analysis; only raise this cap after switching to incremental diffs.
 const MAX_SNAPSHOTS = 20
 export type DiffStats =
  | {
--- a/src/utils/imageResizer.ts
+++ b/src/utils/imageResizer.ts
@@ -162,16 +162,6 @@ interface CompressedImageResult {
  originalSize: number
 }

-/**
- * Per-call image processing limits, overriding the module-level defaults.
- */
-export interface ImageLimits {
-  targetRawSize: number
-  maxWidth: number
-  maxHeight: number
-  maxBase64Size: number
-}
-
 /**
 * Extracted from FileReadTool's readImage function
 * Resizes image buffer to meet size and dimension constraints
@@ -180,13 +170,7 @@ export async function maybeResizeAndDownsampleImageBuffer(
  imageBuffer: Buffer,
  originalSize: number,
  ext: string,
-  limits?: ImageLimits,
 ): Promise<ResizeResult> {
-  const targetRawSize = limits?.targetRawSize ?? IMAGE_TARGET_RAW_SIZE
-  const maxWidth = limits?.maxWidth ?? IMAGE_MAX_WIDTH
-  const maxHeight = limits?.maxHeight ?? IMAGE_MAX_HEIGHT
-  const maxBase64Size = limits?.maxBase64Size ?? API_IMAGE_MAX_BASE64_SIZE
-
  if (imageBuffer.length === 0) {
    // Empty buffer would fall through the catch block below (sharp throws
    // "Unable to determine image format"), and the fallback's size check
@@ -205,7 +189,7 @@ export async function maybeResizeAndDownsampleImageBuffer(

    // If dimensions aren't available from metadata
    if (!metadata.width || !metadata.height) {
-      if (originalSize > targetRawSize) {
+      if (originalSize > IMAGE_TARGET_RAW_SIZE) {
        // Create fresh sharp instance for compression
        const compressedBuffer = await sharp(imageBuffer)
          .jpeg({ quality: 80 })
@@ -226,9 +210,9 @@ export async function maybeResizeAndDownsampleImageBuffer(

    // Check if the original file just works
    if (
-      originalSize <= targetRawSize &&
-      width <= maxWidth &&
-      height <= maxHeight
+      originalSize <= IMAGE_TARGET_RAW_SIZE &&
+      width <= IMAGE_MAX_WIDTH &&
+      height <= IMAGE_MAX_HEIGHT
    ) {
      return {
        buffer: imageBuffer,
@@ -242,19 +226,20 @@ export async function maybeResizeAndDownsampleImageBuffer(
      }
    }

-    const needsDimensionResize = width > maxWidth || height > maxHeight
+    const needsDimensionResize =
+      width > IMAGE_MAX_WIDTH || height > IMAGE_MAX_HEIGHT
    const isPng = normalizedMediaType === 'png'

    // If dimensions are within limits but file is too large, try compression first
    // This preserves full resolution when possible
-    if (!needsDimensionResize && originalSize > targetRawSize) {
+    if (!needsDimensionResize && originalSize > IMAGE_TARGET_RAW_SIZE) {
      // For PNGs, try PNG compression first to preserve transparency
      if (isPng) {
        // Create fresh sharp instance for each compression attempt
        const pngCompressed = await sharp(imageBuffer)
          .png({ compressionLevel: 9, palette: true })
          .toBuffer()
-        if (pngCompressed.length <= targetRawSize) {
+        if (pngCompressed.length <= IMAGE_TARGET_RAW_SIZE) {
          return {
            buffer: pngCompressed,
            mediaType: 'png',
@@ -273,7 +258,7 @@ export async function maybeResizeAndDownsampleImageBuffer(
        const compressedBuffer = await sharp(imageBuffer)
          .jpeg({ quality })
          .toBuffer()
-        if (compressedBuffer.length <= targetRawSize) {
+        if (compressedBuffer.length <= IMAGE_TARGET_RAW_SIZE) {
          return {
            buffer: compressedBuffer,
            mediaType: 'jpeg',
@@ -290,14 +275,14 @@ export async function maybeResizeAndDownsampleImageBuffer(
    }

    // Constrain dimensions if needed
-    if (width > maxWidth) {
-      height = Math.round((height * maxWidth) / width)
-      width = maxWidth
+    if (width > IMAGE_MAX_WIDTH) {
+      height = Math.round((height * IMAGE_MAX_WIDTH) / width)
+      width = IMAGE_MAX_WIDTH
    }

-    if (height > maxHeight) {
-      width = Math.round((width * maxHeight) / height)
-      height = maxHeight
+    if (height > IMAGE_MAX_HEIGHT) {
+      width = Math.round((width * IMAGE_MAX_HEIGHT) / height)
+      height = IMAGE_MAX_HEIGHT
    }

    // IMPORTANT: Always create fresh sharp(imageBuffer) instances for each operation.
@@ -313,7 +298,7 @@ export async function maybeResizeAndDownsampleImageBuffer(
      .toBuffer()

    // If still too large after resize, try compression
-    if (resizedImageBuffer.length > targetRawSize) {
+    if (resizedImageBuffer.length > IMAGE_TARGET_RAW_SIZE) {
      // For PNGs, try PNG compression first to preserve transparency
      if (isPng) {
        const pngCompressed = await sharp(imageBuffer)
@@ -323,7 +308,7 @@ export async function maybeResizeAndDownsampleImageBuffer(
          })
          .png({ compressionLevel: 9, palette: true })
          .toBuffer()
-        if (pngCompressed.length <= targetRawSize) {
+        if (pngCompressed.length <= IMAGE_TARGET_RAW_SIZE) {
          return {
            buffer: pngCompressed,
            mediaType: 'png',
@@ -346,7 +331,7 @@ export async function maybeResizeAndDownsampleImageBuffer(
          })
          .jpeg({ quality })
          .toBuffer()
-        if (compressedBuffer.length <= targetRawSize) {
+        if (compressedBuffer.length <= IMAGE_TARGET_RAW_SIZE) {
          return {
            buffer: compressedBuffer,
            mediaType: 'jpeg',
@@ -422,11 +407,11 @@ export async function maybeResizeAndDownsampleImageBuffer(
      imageBuffer[1] === 0x50 &&
      imageBuffer[2] === 0x4e &&
      imageBuffer[3] === 0x47 &&
-      (imageBuffer.readUInt32BE(16) > maxWidth ||
-        imageBuffer.readUInt32BE(20) > maxHeight)
+      (imageBuffer.readUInt32BE(16) > IMAGE_MAX_WIDTH ||
+        imageBuffer.readUInt32BE(20) > IMAGE_MAX_HEIGHT)

    // If original image's base64 encoding is within API limit, allow it through uncompressed
-    if (base64Size <= maxBase64Size && !overDim) {
+    if (base64Size <= API_IMAGE_MAX_BASE64_SIZE && !overDim) {
      logEvent('tengu_image_resize_fallback', {
        original_size_bytes: originalSize,
        base64_size_bytes: base64Size,
@@ -438,7 +423,7 @@ export async function maybeResizeAndDownsampleImageBuffer(
    // Image is too large and we failed to compress it - fail with user-friendly error
    throw new ImageResizeError(
      overDim
-        ? `Unable to resize image — dimensions exceed the ${maxWidth}x${maxHeight}px limit and image processing failed. ` +
+        ? `Unable to resize image — dimensions exceed the ${IMAGE_MAX_WIDTH}x${IMAGE_MAX_HEIGHT}px limit and image processing failed. ` +
            `Please resize the image to reduce its pixel dimensions.`
        : `Unable to resize image (${formatFileSize(originalSize)} raw, ${formatFileSize(base64Size)} base64). ` +
            `The image exceeds the 5MB API limit and compression failed. ` +
--- a/src/utils/performanceShim.ts
+++ b/src/utils/performanceShim.ts
@@ -105,6 +105,10 @@ function getEntriesByName(name: string, type?: string): PerformanceEntryLike[] {
  return entries.filter(e => e.name === name)
 }

+function getEntries(): PerformanceEntryLike[] {
+  return [...getEntriesByType('mark'), ...getEntriesByType('measure')]
+}
+
 function clearMarks(name?: string): void {
  if (name !== undefined) {
    marks.delete(name)
@@ -128,6 +132,7 @@ const shim = {
  now,
  mark,
  measure: measure as typeof performance.measure,
+  getEntries: getEntries as typeof performance.getEntries,
  getEntriesByType: getEntriesByType as typeof performance.getEntriesByType,
  getEntriesByName: getEntriesByName as typeof performance.getEntriesByName,
  clearMarks: clearMarks as typeof performance.clearMarks,
@@ -140,10 +145,11 @@ const shim = {
    return original.timeOrigin
  },
  get onresourcetimingbufferfull() {
-    return (original as any).onresourcetimingbufferfull
+    return (original as Performance & { onresourcetimingbufferfull?: unknown })
+      .onresourcetimingbufferfull
  },
-  set onresourcetimingbufferfull(_v: any) {
-    // no-op — prevent accumulation
+  set onresourcetimingbufferfull(_v: unknown) {
+    // no-op to prevent accumulation
  },
  toJSON() {
    return original.toJSON()
@@ -156,8 +162,11 @@ const shim = {
 * native Performance reference.
 */
 export function installPerformanceShim(): void {
-  if ((globalThis as any).__performanceShimInstalled) return
-  ;(globalThis as any).__performanceShimInstalled = true
+  const g = globalThis as typeof globalThis & {
+    __performanceShimInstalled?: boolean
+  }
+  if (g.__performanceShimInstalled) return
+  g.__performanceShimInstalled = true
  globalThis.performance = shim
 }