feat: add /tokens /context /cost commands to show token usage and context size

[andrewsruge2501-max]

Feature Request: Token Usage & Context Visibility

It would be very useful to have visibility into token consumption and context size directly from the CLI, similar to Claude Code's /context and /cost commands.

Motivation

Currently, Deep Code already stores token usage data internally in sessions-index.json. According to the docs, each session entry tracks:

"token 用量 and 活跃 token 数"

However, there is no way to view this information from the CLI interface. Users have no visibility into:

• How many tokens they have consumed in the current session
• How much of the context window is being used
• What is consuming the most tokens (system prompt, conversation history, skills, MCP tools)

Proposed Commands

/tokens – Show current session token consumption

Displays the token usage breakdown for the current session:

• Input tokens (this turn)
• Output tokens (this turn)
• Thinking tokens (if thinking mode is enabled)
• Total tokens (entire session)
• Estimated cost (based on model pricing)

/context – Show context window breakdown

Displays what is consuming the context window:

• System prompt size (tokens)
• Conversation history size (# of messages, tokens)
• Skills loaded and their contribution
• Active MCP tools and their descriptions size
• Total context window usage (e.g., 15K / 128K / 1M)

/cost – Show cumulative session cost

Shows the estimated cost of the current session based on model pricing:

• Per-turn cost breakdown
• Total session cost
• Thinking vs non-thinking token cost

Why This Matters

1. Cost awareness – Helps users monitor spend when using paid API models (especially with reasoning/thinking tokens which add significant cost)
2. Debug context limits – When approaching context window limits, users can identify the culprit (bloated history, too many skills, etc.)
3. Optimization feedback – Allows users to measure the impact of prompt optimization, skill trimming, or MCP cleanup
4. Parity with alternatives – Tools like Claude Code already offer /context and /cost; adding these would reduce friction for users migrating to or evaluating Deep Code

Implementation Notes

• The data already exists in ~/.deepcode/projects/<project-code>/sessions-index.json which stores "token 用量" per session entry
• For real-time context window tracking, the token counts could be computed from the messages being sent to the model API
• A lightweight tokenizer or cached counts per message would suffice — no need for full tokenization on every request

---

This is an open-ended feature request. Happy to help with implementation or testing.

[dengmik-commits]

这些信息其实已经可以通过 statusline 插件 实时展示在状态栏中，无需修改 CLI 源码即可实现类似效果（类似我在 #216 回复的做法）。

目前 SessionInfo 已经暴露了以下数据供 statusline module provider 使用：

字段	说明
totalTokens	当前会话总 token 消耗
activeTokens	当前活跃 token 数
maxContextTokens	模型最大上下文窗口大小
requestCount	API 请求次数
messageCount	消息数量
model	当前模型名称
toolUsage	各工具调用次数统计

配置方式

在 .deepcode/settings.json 中添加 statusline 配置：

{
  "statusline": {
    "enabled": true,
    "refreshMs": 3000,
    "providers": [
      {
        "type": "module",
        "id": "tokens",
        "path": "./.deepcode/plugins/tokens.mjs",
        "color": "yellow"
      }
    ]
  }
}

插件示例

创建 .deepcode/plugins/tokens.mjs：

export default function tokensProvider({ session }) {
  if (!session?.activeSessionId) return "no session";
  const tokens = session.totalTokens;
  const maxCtx = session.maxContextTokens;
  const pct = maxCtx > 0 ? (tokens / maxCtx * 100).toFixed(1) : "-";
  return `token: ${tokens} (${pct}% ctx) | req: ${session.requestCount} | msg: ${session.messageCount}`;
}

效果：状态栏会实时显示类似 token: 15234 (11.9% ctx) | req: 8 | msg: 42 的信息。

如果你还想看更详细的 breakdown（system prompt 大小、技能贡献等），也可以写一个更复杂的 module provider 从 sessions-index.json 读取更多数据。

相关文档可参考 statusline.md。

[dengmik-commits]

像上图的 statusline 显示效果，可以加入更多的状态信息，自己写 mjs 插件就行了。

这样更好，是恒值状态，不必调用命令来显示，一直能直观显示