Bun starts Rust port, Claude writes bulk

This is a real signal, but not because Bun “became Rust” overnight; it’s because a major systems project is trying to industrialize AI-generated translation at codebase scale.

• –The important artifact is the migration machinery: `claude/phase-a-port`, `PORTING.md`, and file-for-file conversion rules, not a polished new runtime.
• –That approach reduces ambiguity during translation, but it also risks locking in Zig-era design decisions before humans have fully reviewed the Rust shape.
• –Bun’s Zig fork drift and Zig’s strict no-AI policy make Rust look less like ideology and more like an operational exit ramp.
• –If the branch keeps maturing and test coverage holds up, this becomes a strong demo for agent-assisted large-scale porting; if not, it still shows how far AI can get on a huge codebase before humans take over.
• –Either way, the story matters to AI devs because it’s about using LLMs as migration workers, not just code completion tools.