Does LeanCTX modify my files?

No. LeanCTX only intercepts reads and compresses the output. It never modifies source files.

Which programming languages are supported?

LeanCTX supports 27 languages via tree-sitter AST analysis, preserving code structure while removing redundant syntax and noise.

Can I disable compression for specific files?

Yes. Use path-based rules in config.toml to exclude files from compression or choose a specific read mode for them.

What happens if LeanCTX crashes?

LeanCTX degrades gracefully: reads fall through to native tools, so your agent can keep working without the compression layer.

작동 방식

LeanCTX가 무엇을 제어하는지 AI가 보는 것.

LeanCTX는 AI 에이전트를 위한 context engineering layer입니다: 모든 읽기, 명령어 및 검색에 동일한 루프를 실행하는 작은 Rust 바이너리 하나입니다. 이는 에이전트가 무엇을 읽는지, 세션 전반에 걸쳐 무엇을 기억하는지, 무엇을 접근할 수 있는지 보호하고, 서명된 원장에 무엇을 저장하는지 증명하며, 무엇을 재생하는지 결정합니다. 읽기는 26개 언어에 걸쳐 구조를 파싱하고 노이즈를 제거하므로, 모델에 도달하는 정보는 의도적이고 압축되었으며 증명이 가능합니다. 한 번 설치하면 모든 것이 자동입니다.

시작하기 See the architecture

The context pipeline.

Every request flows through four stages. Your tools stay the same — LeanCTX intercepts silently between your AI tool and the LLM.

Intercept

Your agent calls ctx_read, ctx_shell, or ctx_search. LeanCTX intercepts the call before it reaches the filesystem.

Analyze

Tree-sitter parses the AST. Shell patterns match the command. The content-addressed cache checks for re-reads.

Deliver

Only the signal reaches the model. Signatures, errors, relevant matches — structured, deduplicated, compressed.

One Rust binary. Zero config. Your agent gets better context without knowing LeanCTX exists.

What your agent actually sees.

When your agent reads a file, LeanCTX returns only the structural signature — function signatures, type definitions, and key logic. The full file never enters context.

Explore read modes

ctx_read — src/auth/handler.rs mode: signatures

1pub struct AuthHandler

2 config: AuthConfig,

3 store: Arc<dyn TokenStore>,

⋯ 42 lines omitted

47pub async fn validate(

48 &self, token: &str

49) -> Result<Claims, AuthError>

⋯ 18 lines omitted

68pub fn revoke(&self, id: &str) -> Result<()>

⋯ 9 lines omitted

78impl AuthHandler

79 fn decode_jwt(&self, raw: &[u8]) -> Result<Token>

Shell output, compressed.

A raw git diff produces hundreds of lines. LeanCTX pattern-matches 95+ commands and returns only the meaningful delta — file names, hunks, and error lines.

See all patterns

ctx_shell — git diff HEAD~1 pattern: git-diff

src/proxy/handler.rs

+ let budget = config.max_tokens.unwrap_or(64_000);

− let budget = 64_000;

src/core/compression/engine.rs

+ pub fn compress_with_budget(&self, input: &str, budget: usize)

+ -> CompressedOutput

− pub fn compress(&self, input: &str) -> CompressedOutput

tests/integration/budget_test.rs (new)

+ #[test] fn budget_caps_output_length()

+ #[test] fn budget_default_fallback()

Security built into every call.

Before any file read or shell command executes, LeanCTX validates the path against PathJail, checks the shell allowlist, and redacts detected secrets. lean-ctx doctor shows the full posture.

Security docs

lean-ctx doctor all checks passed

✓Binary signature valid (ad-hoc codesign)

✓PathJail active — root: /Users/dev/project

✓Shell allowlist loaded (14 allow, 6 deny)

✓Secret redaction enabled (.env, credentials.*)

✓LaunchAgent running (pid 4821, uptime 3h12m)

✓Proxy listening on 127.0.0.1:47821

✓MCP server registered (Cursor, Claude Code)

Security posture: containment + secret defense

Last audit: 2 minutes ago · 0 violations

How it works, answered.

The practical details behind the compression layer.

See itin action.

Install LeanCTX and watch your agent's context usage drop.

curl -fsSL https://leanctx.com/install.sh | sh

시작하기 Read the docs →