Explainer Video

Input: [topic] [--length <minutes>] [--voice local|<provider>]

Defaults: length under 3 minutes; voice local. No topic: ask. Work in a new temporary directory; never write into the repository unless the user names a path.

1. Script

State the one question the video answers and the audience. Take facts from the repository or cited sources; label the rest assumption. Never invent numbers or quotes.

Write the beats as a table: beat, narration, visual, estimated seconds. One idea per beat. Narration: plain words, sentences up to 20 words. Visuals follow the explainer method: start from one concrete example with real numbers, build up, transform shapes instead of cutting, keep one idea on screen.

2. Tools

Check what is installed before writing commands: ffmpeg -version, ffprobe -version, and manim --version (or uvx --from manim manim --version when uv exists). Check the installed version's documentation before using an API you have not seen work.

Local voice, first found: the platform's speech command (say -o <file>.aiff on macOS), piper, espeak-ng. None: produce the video with captions only and say so.

A provider voice (for example ElevenLabs) only when the user asks for it and has put the key in an environment variable. Read the key only from that variable; never print, log, or write it to a file. Use the provider's current documentation for the request. Paid usage needs the user's approval of the estimated cost first.