Caching

A cache file (.poops-images-cache.json) is written to the output directory. It records, per image: source mtime, source size, original dimensions, EXIF metadata, and the generated outputs with their dimensions.

{
  "configHash": "a1b2c3...",
  "entries": {
    "photo.jpg": {
      "mtime": 1709312400000,
      "size": 2450000,
      "width": 4032,
      "height": 3024,
      "exif": {
        "make": "Apple",
        "model": "iPhone 15 Pro",
        "fNumber": 1.78,
        "iso": 50,
        "gps": {
          "latitude": { "decimal": 48.8566, "formatted": "48° 51' 23.76\" N" },
          "longitude": { "decimal": 2.3522, "formatted": "2° 21' 7.92\" E" },
          "googleMapsUrl": "https://www.google.com/maps?q=48.8566,2.3522"
        }
      },
      "outputs": [
        { "path": "photo-thumb-150w.webp", "width": 150, "height": 112 },
        { "path": "photo-large-1024w.webp", "width": 1024, "height": 768 }
      ]
    }
  }
}

What gets skipped

In order:

--force — always reprocess.
The config hash changed — sizes, format, quality, skipOriginal or preprocessors differ. Everything is reprocessed.
Per file: skip if the source mtime and size are unchanged and every expected output still exists on disk.
On source deletion in watch mode: remove all generated variants.

Note

Rule 3 checks the outputs, not just the source. Delete a variant by hand and the next run puts it back, without --force.

Configuring it

{ "cache": true }

The default. Cache file at .poops-images-cache.json in the output directory.

{ "cache": false }

No cache file is read or written, and every build reprocesses every image. Watch mode still only processes the changed file — chokidar handles that, not the cache.

{ "cache": ".cache/images.json" }

A custom path, relative to the output directory.

{ "cache": "/tmp/poops-cache.json" }

An absolute path, used as-is.