Subtitle translate + retime + mux

End-to-end pipeline that was built for a 45-minute episode (660 cues) and takes ~25 min wall-clock, ~20 of them in the subagent workflow (~1.2 M subagent tokens for 19 batches).

Scripts live in scripts/ next to this file (call them with absolute paths, expand ~). All Python scripts are uv run scripts with inline deps. ffmpeg/ffprobe come from nix-shell -p ffmpeg (do not add mkvtoolnix to the nix-shell: it builds Qt/Ruby from source and times out; ffmpeg alone is enough).

Ground rules

• The user's own media file is the input. Translating it for them is ordinary work on a provided document. Never paste subtitle text into the chat; agents write to files, and you report only statistics.
• Never modify or overwrite the original video. Write <name>+<LANG>.mkv next to it (mux.sh refuses to overwrite).
• Invoking this skill counts as the user's opt-in for the Workflow tool.

Procedure