@anduril-code/ctx

ctx

Token-aware context management for AI agents.

Agents don't need to dump entire codebases into context. ctx gives them tools to navigate structure, rank by relevance, extract only what they need, and compress what they carry.

It ships as Claude Code skills, an MCP server, a CLI, and a library.

Claude Code Skills

The fastest way to get started. Three slash commands cover the main agent workflows:

Command	When to use
/ctx-explore [question or path]	Navigate a codebase, research a topic, onboard to a new repo
/ctx-review [branch or range]	Code review — compress diffs, outline changed files, surface risks
/ctx-test [command or file]	Run tests — prune noisy output, highlight failures with structural context

Install via add-skill:

# All ctx skills
npx add-skill AndurilCode/ctx

# Or pick specific ones
npx add-skill AndurilCode/ctx --skill ctx-explore --skill ctx-review --skill ctx-test

MCP Server

For any MCP-compatible client (Claude Desktop, Cursor, etc.):

{
  "mcpServers": {
    "ctx": {
      "command": "npx",
      "args": ["ctx-mcp"]
    }
  }
}

Use the lowest-fidelity tool that answers your question:

Navigation (start here for unknown documents) ctx_sections · ctx_locate

Code intelligence ctx_tree · ctx_rank · ctx_gather · ctx_context · ctx_outline · ctx_imports · ctx_symbols · ctx_review · ctx_focus · ctx_verify

Extraction & compression ctx_extract · ctx_compact · ctx_expand · ctx_changes · ctx_prune

AI summarization (lossy, cached) ctx_summarize · ctx_batch

Typical agent reading flow:

ctx_sections → budget the doc
ctx_extract  → pull the sections you need
ctx_compact  → compress if carrying the full doc

CLI

npx @anduril-code/ctx <command> [options]

# Context assembly
ctx gather "authentication flow" --maxTokens 2000
ctx rank "error handling" --glob "**/*.ts"
ctx tree src/ --depth 3

# Code intelligence
ctx outline src/core/compact.ts
ctx imports src/stages/tables.ts
ctx symbols "compact" --kind function
ctx review "security" --diffBase main --evidence
ctx focus src/core/patch.ts::patch
ctx verify src/core/patch.ts --symbol patch --since a3b2
ctx verify src/core/patch.ts --exec

# Document navigation
ctx sections docs/api.md
ctx extract docs/api.md --onlySections "Authentication"
ctx summarize docs/api.md

# Compression
git diff | ctx changes --changes-only
cat test.log | ctx prune --profile test
cat doc.md | ctx compact | ctx expand   # round-trips exactly
ctx roundtrip doc.md                    # round-trip validation command

Library

For embedding compression primitives in your own pipeline:

npm install @anduril-code/ctx

import { compact, expand, pruneLog, compactDiff } from '@anduril-code/ctx';

// Lossless Markdown compression — expand(compact(md)) === md, always
const { output, stats } = compact(md, { dedup: true, stats: true });
console.log(stats.savings); // e.g. 0.38

// Log pruning
const { output: pruned } = pruneLog(testOutput, { profile: 'test' });

// Diff compression
const compressed = compactDiff(gitDiff, { changesOnly: true });

See TypeScript types for full option references.

Development

bun install
bun test
bun run build       # ESM + CJS + type declarations
bun run lint        # biome check
bun run typecheck   # tsc --noEmit

Contributing

Read AGENTS.md — it documents the architecture, dependency rules, and invariants.

MIT