blacksmith-testboxlisted

# cmux-tui Blacksmith Testbox A Testbox is a persistent 32 vCPU Linux VM that keeps its disk between commands. CI warms it once, and every later build reuses the Cargo registry, the Zig cache, and `target/`. A clean cmux-tui build costs about 130 s on a warm box, a no-op about 0.2 s, and a one-file change about 8 s. ## Warm your own box first, before you read code Warmup takes about four minutes of wall clock you cannot compress. Starting it at the end of your task means waiting; starting it in your first minute means it is ready by the time you know what to build. So: 1. If your task might compile cmux-tui, dispatch the warmup **before** you open a single source file, then read code while it hydrates. The exception is an evidence run: `benchmark.md` requires its preflight, `OUT_ROOT`, and receipt to exist before warmup, so read that plan first and accept the delay. 2. Warm **your own** box. One box belongs to one worktree and one agent, because `blacksmith testbox run` synchronizes your worktree onto it with `rsync --delete`. Two agents on one ID overwrite each other's source and corrupt each other's timings. 3. Never adopt a box you find in `blacksmith testbox list --all`. A box you did not warm is someone else's working state. 4. Stop your box the moment you are done, and always pass `--idle-timeout` so a crashed agent cannot leak a running VM. Skip the lane entirely for Swift, Xcode, XCUITest, GUI, and app-host work. That is macOS, and it belo