Guardian Runtime – AI Agent Cost & Security Firewall

A local proxy that sits between AI coding agents (Claude, Cursor, Aider) and their APIs to enforce hard budgets, prevent runaway costs, and add security controls. Solves the problem of AI agents spiraling with uncontrolled API calls.

Token costs from agentic coding loops have become a genuine pain point in 2024–2025 as Claude, GPT-4o, and Gemini pricing adds up fast when Cursor or Aider misinterprets a task and hammers the API for minutes unchecked. No clear incumbent owns this specific proxy-layer niche, though LiteLLM's budget controls and basic rate limiting in some SDKs are partial substitutes that technically-inclined users already reach for. The $1k–5k/mo revenue band is plausible but tight — this is a tool developers want free or near-free, and willingness to pay depends entirely on whether the buyer has already been burned by a surprise invoice. The single most likely failure mode is distribution: the people who need it most are solo developers who'll spend 90 minutes building their own bash script instead of paying $15/month, leaving the addressable paying market much smaller than the noise around the problem suggests.