55/55 TESTS PASSING · BUILT BEFORE THE LEAK

AI Coding Agent
in Rust

A 5.4MB binary that runs Claude as a full coding agent on your Max subscription. Zero API costs. 8 tools. MCP client. Prompt caching. Semantic compaction. 19-event hook system. Ships as a single binary.

5.4MB

Binary Size

55/55

Tests Passing

9,390

Lines of Rust

API Cost

View on GitHub Test Results

claude-agent

$ ./claude-agent

claude-agent v1.1.0 (Rust)

claude-opus-4-6 · backend: cli (Claude Max)

8 tools · 50 MCP servers · 8 skills · 19 hook events

agent> write a fizzbuzz in Rust, compile it, run it

[write] /tmp/fizzbuzz.rs

[bash] rustc /tmp/fizzbuzz.rs -o /tmp/fizzbuzz && /tmp/fizzbuzz

1, 2, Fizz, 4, Buzz, Fizz, 7, 8, Fizz, Buzz, 11, Fizz, 13, 14, FizzBuzz...

Done in 21s · 0 API tokens billed

Architecture

11 Layers, 27 Source Files

A complete agent architecture in Rust — dual inference backends, prompt caching, semantic compaction, 19-event hook system, MCP client, and interactive tool confirmation.

Inference Engine

Dual backend: CLI (claude -p, $0) or direct API with SSE streaming. Prompt cache breakpoints for API mode.

src/inference.rs

Tool System

8 built-in tools: bash, read, write, edit, glob, grep, web_fetch, agent. Trait-based dispatch with interactive confirmation.

src/tools/

MCP Integration

Full JSON-RPC 2.0 client with stdio transport. Auto-discovery from ~/.mcp.json. 5s init timeout.

src/mcp/

Skills & Hooks

8 built-in skills + user skills. 19-event hook system with priority ordering, glob matchers, and user-configurable hooks from JSON.

src/skills.rs, src/hooks.rs

Permissions

Controls which tools and paths the agent can access. Sandboxing for safe execution.

src/permissions.rs

Context Manager

Static/dynamic prompt split for cache optimization. Semantic compaction extracts files, commands, errors, and key points.

src/context.rs

Memory System

Persistent memory backed by file system. Reads/writes memory across sessions.

src/memory.rs

Auth Layer

Handles authentication. Strips ANTHROPIC_API_KEY to use subscription auth.

src/auth.rs

Type System

Message types, tool schemas, API response structs. serde-powered (de)serialization.

src/types.rs

Telemetry

Tracks token usage, response times, tool call counts. Session metrics.

src/telemetry.rs

CLI & REPL

Interactive REPL with rustyline. Flag parsing, colored output, status display.

src/main.rs, src/flags.rs

Built-in Tools

8 Native Tools

Each tool is a separate Rust module with async execution, permission guards, hook dispatch, and optional interactive confirmation.

bash

Execute shell commands

📄

read

Read file contents

✏️

edit

String replacements

📝

write

Create/overwrite files

🔍

glob

Pattern file search

🔎

grep

Content search (regex)

🌐

web_fetch

HTTP requests

🤖

agent

Spawn sub-agents

Verified

55/55 Tests Passing

Unit tests + integration tests covering all tools, permissions, hooks, compaction, prompt caching, and session persistence.

Simple math (2+2)PASS11s

Bash tool (ls)PASS13s

Read tool (Cargo.toml)PASS17s

Grep tool (async fn)PASS20s

Write + Read chainPASS16s

Multi-step (Python)PASS18s

Built-in commandsPASS<1s

Edit toolPASS39s

Glob tool (*.toml)PASS13s

Empty promptPASS<1s

Error: missing filePASS27s

Special charactersPASS13s

Complex bash (find+wc)PASS25s

3-step tool chainPASS107s

Deep analysisPASS160s

Error propagationPASS12s

Security: rm -rf /REFUSED13s

WebFetch (httpbin)PASS15s

Unicode + emojiPASS31s

Non-zero exit codePASS18s

Read missing filePASS11s

Grep zero matchesPASS17s

Write+compile RustPASS21s

Skill dispatchPASS<1s

Glob + line countPASS22s

Read-edit-verify-undoPASS48s

Bash with sleepPASS17s

Large stdout (500 lines)PASS41s

Why This Matters

Claude Code Alternative, Built in Rust

Clean-room Rust implementation that predates the OpenClaude leak. 40x smaller, 20x faster startup, dual-backend.

$0 / month

Zero API Cost

Calls claude -p under the hood, which uses your Max subscription's OAuth token. No per-token billing. Run it all day — same flat rate.

FULLY MODIFIABLE

You Own the Code

9,390 lines of Rust you can read, modify, extend. Add tools, change behavior, strip telemetry — it's yours. Published on crates.io as both a binary and a library.

5.4MB BINARY

Single Binary Deploy

No Node.js runtime, no npm install, no dependency tree. One cargo install claude-agent-rs and you have a self-contained binary with SQLite bundled.

EXTENSIBLE

MCP + Skills + Hooks

Automatically discovers your MCP servers, skills, and hooks from Claude config. Extends the tool surface without modifying the agent.

Feature	Claude Code	claude-agent-rs
Source Code	Leaked / OpenClaude fork	Clean-room Rust (MIT)
Binary Size	~200MB (Node.js)	5.4MB
API Cost	Subscription or API	Subscription only ($0 extra)
Custom Tools	MCP only	Native Rust + MCP
Modify Behavior	Config only	Full source access
Startup Time	~2s	<100ms
Embeddable	No	Library or binary

Roadmap

All Milestones Shipped

v1.1.0 live on crates.io. View releases

v1.0.0 SHIPPED

Production Ready

11 layers, 8 tools, dual backends (CLI + API), SSE streaming, MCP client, SQLite sessions, sub-agents with worktree isolation, plugins, skills, 55 tests.

v1.1.0 SHIPPED

OpenClaude Features

Prompt cache breakpoints, semantic compaction, 19-event hook system with priority ordering, interactive tool confirmation, NIM security audit.

v1.2.0

Cross-Platform

Windows support, Homebrew formula, Docker (scratch), GitHub Actions release pipeline, CI/CD.

v1.3.0

Deep Integration

OpenTelemetry, TUI dashboard, native inference (bypass CLI), WebSocket backend, WASM target.

AI Coding Agentin Rust