cc-proxy-detector

Detect backend origins of Claude Code proxies via response fingerprints.

44|3|Updated Feb 10, 2026
One-click install
npx skills add https://github.com/zxc123aa/cc-proxy-detector --skill cc-proxy-detector
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: cc-proxy-detector
Source: https://github.com/zxc123aa/cc-proxy-detector/tree/main
Command: npx skills add https://github.com/zxc123aa/cc-proxy-detector --skill cc-proxy-detector

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires requests, and includes scripts (resource) and references (resource) components.

What problem does it solve?

Detects the real backend origin of Claude Code proxy/relay services when users need to verify whether traffic is going to official Anthropic, AWS Bedrock (Kiro), or Google Vertex AI (Antigravity), and when proxies attempt to disguise their routing.

Core Features & Use Cases

  • Three-backend detection: Identifies Anthropic API, AWS Bedrock (Kiro), or Google Vertex AI (Antigravity) routing based on response fingerprints.
  • Mixed-model scanning: Detects when a single proxy routes different models to different backends.
  • Anti-spoofing evidence: Uses negative evidence for missing Anthropic-only fields to catch deep spoofing and distinguishes dynamic vs forged ratelimit behavior.
  • Practical outputs for review: Produces per-model verdicts with confidence, evidence chains, and fingerprint details you can manually audit.

Quick Start

Run the detector against your proxy endpoint by setting the base URL and API key in environment variables and then executing the provided Python script to generate a backend verdict report.

Frequently Asked Questions about cc-proxy-detector

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I detect the real backend behind a Claude Code proxy endpoint?

Claude proxy verification distinguishes official Anthropic, AWS Bedrock, and Google Vertex AI backends by probing the /v1/messages endpoint for tool_id, msg_id, and thinking_signature fingerprints, scoring responses against a three-source matrix to produce structured per-model verdicts.

Can I check if my proxy is routing different models to different backends?

Yes, you can check for mixed routing by performing a multi-model scan that sends deterministic probes to each model, identifying when a single proxy routes traffic to different backends like AWS Bedrock or Google Vertex AI by comparing extracted response fingerprints and generating per-model verdicts with confidence scores.

How does anti-spoofing detection work for Claude API proxies?

Anti-spoofing detection works by analyzing negative evidence from missing Anthropic-only fields and distinguishing dynamic ratelimit behavior from forged headers, catching deep spoofing attempts that disguise routing by validating actual tool execution and thinking signatures against expected backend fingerprints.

What do I need to run a proxy backend detection script?

Running proxy backend detection requires the requests dependency, a configured proxy base URL, and an API key set as environment variables, enabling the Python script to probe the /v1/messages endpoint and generate structured verdict reports.

What are the limitations of fingerprint analysis for proxy verification?

Fingerprint analysis limitations include reliance on deterministic probes returning specific fields like thinking_signature and usage, meaning proxies stripping or forging these fields require negative evidence validation, and dynamic ratelimit checks are needed to catch deep spoofing beyond simple header inspection.