Pixellab library expansion

README.md

@@ -15,7 +15,7 @@ There are two part libraries:
 pip install -r requirements.txt
 ```
 
-You only need an [OpenRouter](https://openrouter.ai) API key if you want the type picked automatically. Skip the key by passing `--type`.
+You only need an [OpenRouter](https://openrouter.ai) API key if you want the type picked automatically. Set `OPENROUTER_API_KEY` in the environment or in `.env`, or skip the key by passing `--type`.
 
 ## Generate a sprite
 
@@ -83,7 +83,11 @@ python pixellab_library.py cost                          # spend so far (pixella
 python validate_parts.py --library pixellab --sample 3000
 ```
 
-To change a part, edit its spec (new `seed` or wording), then run `generate <body> --parts <part> --force` and `extract <body>`. Regenerating a base deletes that body's old edits.
+To change a part, edit its spec (new `seed` or wording), then run `generate <body> --parts <part> --force` and `extract <body>`. Regenerating a base deletes that body's old edits and variants.
+
+A new body needs no parts of its own: for each slot without a part, `generate` makes a probe edit (a standard horn pair, wing pair or tail) that is used only to find where that slot attaches. A body's `variants` are edits of its base ("make it chubbier with crimson stripes"): the same creature idea with a different look. They share the parent's attach points and tags. `generate` runs up to 10 PixelLab jobs at once, shared between all processes. `preview <body>` writes one review sheet per family (base, attach points, a test fit with library parts, every variant), and `preview --sheet out.png <bodies...>` shows many raw bases on one image.
+
+`generate` stops before starting new work once the month's included PixelLab generations drop to 800 (`PIXELLAB_RESERVE` changes the floor), so a big run can't use up the whole monthly allowance.
 
 ## Classic library