Overview & ArchitectureCore Problem
Why Raw Diffs Fail in AI Coding
Why line-based git diffs are blind to semantic breakage caused by autonomous coding agents.
AI coding assistants (Cursor, Claude Code, Antigravity, Devin, Copilot) write code in bursts across multiple files. A standard git diff only sees character additions and subtractions (+1 / -1). It has no awareness of syntax trees, method signatures, return type mutations, or downstream callers. Change Firewall acts as an intelligent AST gate between AI code output and your main repository.
A 1-line return type change (e.g., returning { user } instead of user) looks innocent in git diff, but breaks every single client component at runtime.
| Analysis Vector | Traditional Git Diff | Change Firewall AST Engine |
|---|---|---|
| Contract Mutations | Hidden as plain text change | Analyzed against AST function contracts |
| Downstream Blast Radius | 0% caller awareness | Reverse import graph traversal up to 3 hops |
| Merge Readiness | Requires human deciphering | Deterministic 0-100 score + blocking gate |
| AI Self-Healing | Manual review cycles | Stdio JSON-RPC MCP server for autonomous fix |
- 100% offline & local execution (zero token costs, zero telemetry)
- Instant TypeScript Compiler API AST traversal in milliseconds
- Full reverse dependency graph mapping across your entire repository