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.

So funktioniert's

Wie LeanCTX kontrolliert, was deine KI sieht.

LeanCTX ist der Context-Engineering-Layer für KI-Agenten: eine kleine Rust-Binary, die bei jedem Read, Befehl und jeder Suche dieselbe Schleife durchläuft. Sie entscheidet, was deine Agenten lesen, erinnert sich an Gelerntes über Sessions hinweg, schützt, was sie anfassen, beweist in einem signierten Ledger, was sie sparen, und spult zurück, was sie gesehen haben. Reads werden über 26 Sprachen hinweg auf Struktur geparst und vom Rauschen befreit, sodass nur durchkommt, was bewusst, komprimiert und beweisbar ist. Du installierst es einmal. Alles andere ist automatisch.

Loslegen 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

Loslegen Read the docs →