Show HN: Ctxfw – In-memory AST pruner and token firewall for Cursor and Claude

Category: devtools

Tags: ast, prompt-injection, context-management, mcp, token-optimization, security

Score: 7.0/10 (Innovation: 7, Technical: 7, Documentation: 8, Utility: 6)

CTXFW is a local context firewall and MCP gatekeeper that prunes peripheral code from ASTs to drastically reduce token usage and deterministically blocks prompt injection via a rule-based sieve. It targets AI coding agents like Cursor and Claude, offering significant cost savings and a zero-egress security boundary.

Target audience: AI engineers, backend developers, devops

Repository: https://github.com/heuristicolab/ctxfw · Python · Apache-2.0 · 7 stars

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