Private build state
Every worktree keeps its own writable Cargo and rustc state. There is no shared mutable target directory.
Rust worktree cache seeding
New worktree. Near-warm first build.
cargo-warm forks build state from a checkout that already paid the compile cost into a separate writable cache for the new worktree. You keep isolation without throwing away all of the useful work Cargo and rustc already did.
The model
Fork compiler state. Do not share its writable directory.
A warm main checkout is valuable state. cargo-warm makes that state cheap to inherit while keeping every agent, branch, and worktree independently writable.
Cheap inheritance
APFS clones on macOS and reflinks on Linux let a warm checkout seed another without physically copying every block up front.
Cargo stays authoritative
A seed is only a starting point. Cargo and rustc still decide what is fresh, stale, or incrementally reusable.
Built for hooks
Use one CLI call from an IDE, agent runtime, shell script, or Git worktree hook. No Golden Goose-specific integration is required.