Catch the shock. Stop AI agents from burning tokens on infinite loops.

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Snubber: Two Products, One Safety Layer

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What Is Snubber?

Snubber is the runtime safety layer for autonomous agents. It detects and blocks tool‑call loops before they burn tokens or crash your infrastructure. It works in any harness, any language, in under 70 microseconds.

We ship two products that serve different audiences:

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Product 1: Snubber Core

The Engine

The Snubber Core is a C ABI library written in Rust (no_std). It does exactly one thing: it takes a tool call, checks it against a sliding window of recent calls, and returns a decision — ALLOW, WARN, BLOCK_RETRY, or BLOCK_HALT.

Key properties:

• <2µs overhead – zero allocations in the hot path
• <200KB binary – no runtime dependencies
• C ABI – embeds anywhere C runs (Python, Node.js, Go, Rust, C++)

What it does:

• Semantic loop detection (ignore_args: true) – catches the same tool with different arguments
• Error‑aware counting (count_mode: ErrorsOnly) – ignores legitimate polling
• Circuit breaker – per‑tool cooldown prevents retry storms
• Output validation – regex + JSON schema on tool outputs

Who it’s for:

• Harness developers (LangChain, CrewAI, AutoGen maintainers)
• Systems engineers embedding safety in custom agents
• Rust developers building agent frameworks

Distribution:

• Crates.io: cargo add snubber
• GitHub: snubber-rs/snubber
• Pre‑built binaries: libsnubber.so, libsnubber.dylib, snubber.dll

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Product 2: Snubber Adapters + Reference Harness

The Drop‑In Safety Layer

For developers who don’t want to build from scratch, Snubber provides ready‑to‑use adapters that wrap the core into your existing agent harness. One line of code, instant safety.

Available adapters:

• LangChain – pip install snubber-langchain
• CrewAI – pip install snubber-crewai
• AutoGen – pip install snubber-autogen
• LangGraph – pip install snubber-langgraph
• Node.js (coming soon) – npm install @snubber/langchain

Also included:

• Snubber Harness – a complete, safety‑first Rust ReAct agent harness. It’s open‑source and serves as a reference implementation, showcasing how to build a harness with Snubber embedded as a first‑class primitive.

Who it’s for:

• Python developers using LangChain, CrewAI, AutoGen, or LangGraph
• Teams that want to drop safety into their existing codebase without rewriting
• Early adopters who want to see Snubber in action before committing

Distribution:

• PyPI: pip install snubber-*
• npm: npm install @snubber/*
• Docker: docker run snubber/harness

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How They Work Together

┌─────────────────────────────────────────────────────────────┐
│                      YOUR APPLICATION                       │
│  ┌─────────────────────────────────────────────────────┐    │
│  │   LangChain / CrewAI / AutoGen / LangGraph         │    │
│  └─────────────────────┬───────────────────────────────┘    │
│                        │                                     │
│  ┌─────────────────────▼───────────────────────────────┐    │
│  │   Snubber Adapter (Python / JS / Go)                │    │
│  │   – Calls the C ABI core                            │    │
│  │   – Intercepts tool calls                           │    │
│  │   – Injects SYSTEM INTERCEPT messages               │    │
│  └─────────────────────┬───────────────────────────────┘    │
│                        │                                     │
│  ┌─────────────────────▼───────────────────────────────┐    │
│  │   Snubber Core (libsnubber.so)                      │    │
│  │   – Sliding window                                  │    │
│  │   – Semantic detection                              │    │
│  │   – Circuit breaker                                 │    │
│  └─────────────────────────────────────────────────────┘    │
└─────────────────────────────────────────────────────────────┘

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The Value Proposition

User	Problem	Snubber Solution
Python developer	LangChain loop detection is experimental	pip install snubber-langchain – instant safety
Rust developer	Need embeddable loop detection	cargo add snubber – <2µs, zero allocations
Enterprise team	429 crashes, token waste	Snubber blocked loops in 4 harnesses, saved 100% of tokens
Harness maintainer	Want to add safety to your framework	Snubber Core – C ABI, embeddable anywhere

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Summary

Product	What It Is	Who It’s For	Get It
Snubber Core	C ABI library (Rust no_std)	Framework devs, systems engineers	cargo add snubber
Snubber Adapters	Drop‑in wrappers for LangChain, CrewAI, AutoGen, LangGraph	Python agent developers	pip install snubber-*
Snubber Harness	Reference Rust ReAct agent harness	Rust developers, early adopters	cargo install snubber-harness

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License

MIT — use it, fork it, ship it. See LICENSE.