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.

Cómo Funciona

Cómo LeanCTX controla lo que ve tu IA.

LeanCTX es la capa de context engineering para agentes de IA: un pequeño binario Rust que ejecuta el mismo bucle en cada lectura, comando y búsqueda. decide lo que leen tus agentes, recuerda lo que aprenden a través de las sesiones, protege lo que tocan, prueba lo que guardan en un libro mayor firmado, y reproduce lo que vieron. Las lecturas se analizan para estructura en 26 idiomas y se les elimina el ruido, por lo que lo que llega al modelo es intencional, comprimido y comprobable. Lo instalas una vez. Todo lo demás es automático.

Empezar 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

Empezar Read the docs →