ContextSlim

Save 50%+ AI context tokens without losing critical code semantics.

GitHub: lilite572-cyber/context-slim

Cursor, Claude, and other coding agents re-read whole files on every turn. Most of that budget is JSDoc, unused imports, and DTO mappers. ContextSlim parses JS/TS (Babel) and PHP (php-parser), hollows the noise, and keeps try/catch, auth methods, env() / process.env, and markers like FIXME / SECURITY / В ПРОД НЕ ГНАТЬ.

Before / after

Measured on the real-world billing controller in tests/fixtures/real_world_controller.ts (--signatures-only):

| | Tokens | What you keep | |---|---:|---| | Before | 3,522 | comments, mappers, unused imports, every method body | | After | 1,408 | signatures + critical bodies + protected comments | | Savings | 60% (10 labels kept) | try/catch, authorize / login, FIXME, В ПРОД НЕ ГНАТЬ |

CLI stats use gpt-tokenizer (o200k_base, GPT-4o / GPT-5 family) and print to stderr. Slim source goes to stdout.

npx @idmxgne/context-slim .
# Исходный размер: 3,522 токенов -> Сжатый: 1,408 токенов. Экономия: 60% ...

Quick start

npx @idmxgne/context-slim .
npx @idmxgne/context-slim ./src --signatures-only
npx @idmxgne/context-slim ./src --out slim.txt

From a clone:

npm i && npm run build
node dist/cli.js ./src

MCP server (Cursor, Windsurf, Claude Code)

Bin: context-slim-mcp → dist/mcp.js. Official @modelcontextprotocol/sdk Server + StdioServerTransport. Do not write logs to stdout.

Prompt use-slim-context:

Always prioritize using read_slim_file tool when reading source code files to optimize context window.

Tools:

| Tool | Args | Result | |---|---|---| | read_slim_file | path (string), signaturesOnly (boolean, default true) | compressed source | | get_slim_stats | none | last run: tokens before / after, % saved, protected label count |

Cursor

Merge into ~/.cursor/mcp.json (ready-made copy: examples/cursor-mcp.json):

{
  "mcpServers": {
    "context-slim": {
      "command": "node",
      "args": ["/ABSOLUTE/PATH/TO/context-slim/dist/mcp.js"]
    }
  }
}

After npm publish:

{
  "mcpServers": {
    "context-slim": {
      "command": "npx",
      "args": ["-y", "--package=@idmxgne/context-slim", "context-slim-mcp"]
    }
  }
}

Restart Cursor and ask the agent to read_slim_file on a fat controller.

Windsurf

Same mcpServers block in Windsurf's MCP config (~/.codeium/windsurf/mcp_config.json, or the MCP panel in settings). Point command at node + dist/mcp.js, or at npx as above.

Claude Code / Claude Desktop

Claude Desktop — merge examples/claude_desktop_config.json into claude_desktop_config.json:

{
  "mcpServers": {
    "context-slim": {
      "command": "node",
      "args": ["/ABSOLUTE/PATH/TO/context-slim/dist/mcp.js"]
    }
  }
}

Claude Code:

claude mcp add context-slim -- node /ABSOLUTE/PATH/TO/context-slim/dist/mcp.js

Safe labels (.contextslimrc + isCriticalNode)

A node is never hollowed when isCriticalNode says so:

• comments matching CRITICAL, FIXME, TODO, SECURITY, DONT TOUCH, В ПРОД НЕ ГНАТЬ, @keep
• try / catch
• methods whose names look like auth (authorize, login, jwt, csrf, …)
• env(), getenv(), process.env
• PHP/Laravel: $this->hasMany / $this->belongsTo (and other Eloquent relations) and scope* methods

Repo: https://github.com/lilite572-cyber/context-slim

Put extra phrases in .contextslimrc at the project root:

{
  "keep_patterns": ["HACK", "LEGACY"]
}

entry_patterns (defaults: index / cli / main / app / server) keep ordinary function bodies even without --signatures-only. Dependency files are hollowed; pass --signatures-only (or MCP signaturesOnly: true) to hollow everything that is not critical.

Install / publish

npm i
npm test
npm run build

Bins: context-slim → dist/cli.js, context-slim-mcp → dist/mcp.js. npm: @idmxgne/context-slim. License: MIT.

License

MIT