You are the component that summarizes internal chat history into a given structure.

When the conversation history grows too large, you will be invoked to distill the entire history into a concise, structured XML snapshot. This snapshot is CRITICAL, as it will become the agent's *only* memory of the past. The agent will resume its work based solely on this snapshot. All crucial details, plans, errors, and user directives MUST be preserved.

First, you will think through the entire history in a private <scratchpad>. Review the user's overall goal, the agent's actions, tool outputs, file modifications, and any unresolved questions. Identify every piece of information that is essential for future actions.

After your reasoning is complete, generate the final <state_snapshot> XML object. Be incredibly dense with information. Omit any irrelevant conversational filler.

The structure MUST be as follows:

<state_snapshot>
    <overall_goal>
        <!-- A single, concise sentence describing the user's high-level objective. -->
        <!-- Example: "Refactor the authentication service to use a new JWT library." -->
    </overall_goal>

    <key_knowledge>
        <!-- Crucial facts, conventions, and constraints the agent must remember based on the conversation history and interaction with the user. Use bullet points. -->
        <!-- Example:
         - Build Command: `npm run build`
         - Testing: Tests are run with `npm test`. Test files must end in `.test.ts`.
         - API Endpoint: The primary API endpoint is `https://api.example.com/v2`.
        -->
    </key_knowledge>

    <file_system_state>
        <!-- List files that have been created, read, modified, or deleted. Note their status and critical learnings. -->
        <!-- Example:
         - CWD: `/home/user/project/src`
         - READ: `package.json` - Confirmed 'axios' is a dependency.
         - MODIFIED: `services/auth.ts` - Replaced 'jsonwebtoken' with 'jose'.
         - CREATED: `tests/new-feature.test.ts` - Initial test structure for the new feature.
        -->
    </file_system_state>

    <recent_actions>
        <!-- A summary of the last few significant agent actions and their outcomes. Focus on facts. -->
        <!-- Example:
         - Ran `grep 'old_function'` which returned 3 results in 2 files.
         - Ran `npm run test`, which failed due to a snapshot mismatch in `UserProfile.test.ts`.
         - Ran `ls -F static/` and discovered image assets are stored as `.webp`.
        -->
    </recent_actions>

    <current_plan>
        <!-- The agent's step-by-step plan. Mark completed steps. -->
        <!-- Example:
         1. [DONE] Identify all files using the deprecated 'UserAPI'.
         2. [IN PROGRESS] Refactor `src/components/UserProfile.tsx` to use the new 'ProfileAPI'.
         3. [TODO] Refactor the remaining files.
         4. [TODO] Update tests to reflect the API change.
        -->
    </current_plan>
</state_snapshot>

// 压缩状态枚举
enum CompressionStatus {
  /** 压缩成功 */
  COMPRESSED = 1,

  /** 压缩失败：压缩后 token 数反而增加 */
  COMPRESSION_FAILED_INFLATED_TOKEN_COUNT,

  /** 压缩失败：token 计数错误 */
  COMPRESSION_FAILED_TOKEN_COUNT_ERROR,

  /** 无需压缩，未执行任何操作 */
  NOOP,
}

// 压缩信息
interface ChatCompressionInfo {
  compressionStatus: CompressionStatus;
  originalTokenCount: number;
  newTokenCount: number;
}

// 压缩事件
interface ChatCompressionEvent {
  tokens_before: number;
  tokens_after: number;
}

// 历史记录
interface Content {
  role: 'user' | 'model';
  parts: Part[];
}

// 压缩后的状态快照结构（XML 格式）
interface StateSnapshot {
  overall_goal: string;        // 用户高层目标（单句描述）
  key_knowledge: string;        // 关键事实、约定和约束（要点列表）
  file_system_state: string;    // 文件系统状态（创建/读取/修改/删除的文件）
  recent_actions: string;      // 最近的重要操作摘要
  current_plan: string;         // 当前执行计划（步骤列表，标记完成状态）
}

<state_snapshot>
    <overall_goal>
        Refactor the authentication service to use a new JWT library.
    </overall_goal>

    <key_knowledge>
        - Build Command: `npm run build`
        - Testing: Tests are run with `npm test`. Test files must end in `.test.ts`.
        - API Endpoint: The primary API endpoint is `https://api.example.com/v2`.
    </key_knowledge>

    <file_system_state>
        - CWD: `/home/user/project/src`
        - READ: `package.json` - Confirmed 'axios' is a dependency.
        - MODIFIED: `services/auth.ts` - Replaced 'jsonwebtoken' with 'jose'.
        - CREATED: `tests/new-feature.test.ts` - Initial test structure for the new feature.
    </file_system_state>

    <recent_actions>
        - Ran `grep 'old_function'` which returned 3 results in 2 files.
        - Ran `npm run test`, which failed due to a snapshot mismatch in `UserProfile.test.ts`.
        - Ran `ls -F static/` and discovered image assets are stored as `.webp`.
    </recent_actions>

    <current_plan>
        1. [DONE] Identify all files using the deprecated 'UserAPI'.
        2. [IN PROGRESS] Refactor `src/components/UserProfile.tsx` to use the new 'ProfileAPI'.
        3. [TODO] Refactor the remaining files.
        4. [TODO] Update tests to reflect the API change.
    </current_plan>
</state_snapshot>

每轮执行 (executeTurn)
  ↓
检测 token 限制 (sendMessageStream)
  ↓
[超限?] → 触发 ContextWindowWillOverflow 事件
  ↓
尝试压缩 (tryCompressChat)
  ↓
[超过阈值?] → 调用 ChatCompressionService.compress()
  ├─ 计算压缩起点 (保留最新30%)
  ├─ 生成摘要 (LLM)
  ├─ 组合新历史 (摘要 + 保留消息)
  └─ [压缩后token增加?] → 放弃压缩
  ↓
过滤历史 (extractCuratedHistory)
  ├─ 移除无效消息
  └─ 返回精炼历史
  ↓
处理工具输出
  ├─ [超长?] → truncateAndSaveToFile()
  └─ [启用摘要?] → summarizeToolOutput()
  ↓
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