Claude Editing Skills plugin

---
name: explainer
description: Edits a talking-head clip into an explainer reel. The speaker sits low in a rounded panel on a light backdrop with their head breaking out over its top edge, and the top of the frame explains the point with visuals (a before-to-after comparison with an arrow, or a numbered list). White captions set the key words in a serif. Use when the user runs /explainer or asks for "me at the bottom, visuals on top" on a 9:16 clip.
---

# /explainer

```
┌──────────────────────┐
│   Steal what works   │  title, one word in serif italic
│ [before] ⟶ [after]   │  compare: card, drawn arrow, reveal  (or a numbered list)
│      ╭──head──╮      │  the head breaks out over the panel
│ ╭────┴────────┴────╮ │
│ │  speaker, captions│ │  rounded panel, eye line = its top edge
│ ╰──────────────────╯ │
└──────────────────────┘
```

## First use
This skill's folder is the "Base directory" Claude Code shows when it loads it. Resolve the kit from it (works through symlinks), and set up once:
```bash
SKILL_DIR="<base directory of this skill>"   # the path Claude Code printed as "Base directory for this skill"
KIT=$(python3 -c 'import os,sys;print(os.path.realpath(os.path.join(sys.argv[1],"..","..","kit")))' "$SKILL_DIR")
PY="$KIT/.venv/bin/python"; [ -x "$PY" ] || bash "$KIT/setup.sh" --cutout
```
`GROQ_API_KEY` must be set to transcribe (free at console.groq.com). Needs ffmpeg and Node.

## Steps
1. **Clip.** Use the 9:16 clip the user gave (any size; it is cropped to 1080x1920). Ask for it only if none was given.
2. **Words.** `"$PY" "$KIT/reel.py" words <video>` prints every word with its time (it transcribes on first use). It prints one sentence per line with `[ends …]`, the time its last word ends. Pick one stretch of 3 to 8 seconds that makes ONE point, made of whole sentences: `start` is the first word's time and `end` is the last sentence's `[ends …]` (source seconds).
3. **Eye line.** `"$PY" "$KIT/reel.py" frame <video> <a time in the stretch> frame.jpg`, then look at the image. The red ruler is in 1080x1920 pixels; read the y of the eyes. That is `eye_y` (about 700 to 800 for a normal framing).
4. **Spec.** Write `<clip name>.explainer.json` next to the clip (fields below). Paths in a spec are relative to the spec file. Every time is either seconds from `start` or a spoken word to anchor on (`"viral"`, `"viral#2"` for its second time, `"viral+0.2"`). Prefer words: they stay right when you move `start`.
5. **Build.** `"$PY" "$SKILL_DIR/build.py" <spec.json>`. It cuts the stretch, cuts the speaker out (about 0.1 s per frame), renders with HyperFrames and writes `<out>.sheet.jpg`.
6. **Check.** Look at the sheet. Red is what Instagram covers. Fix the spec and rebuild if:
   - the title or visuals sit in the red
   - a caption covers the mouth, or sits within 80 px of the red bottom zone (move `caption_top`)
   - a caption shows a word from outside the stretch (move `start` or `end` to the sentence edges)
   - the head doesn't break out over the panel (move `eye_y`)
   - an image is missing or squashed
7. **Hand over** the mp4 path and say in one line what each visual shows.

## Spec
```json
{
  "video": "my-clip.mp4", "start": 21.4, "end": 25.66, "out": "my-clip.explainer.mp4",