Marking third-party sources

Source Map v3 maps can carry an ignoreList of source array indices that debuggers should step over. isIgnored() exposes that normative field.

$position = $map->lookup(42, 17);

if ($position !== null && $map->isIgnored($position->sourceFileName)) {
    // Vendor or framework code. Skip in UI.
}

The lookup accepts either the raw entry from sources[] or its sourceRoot resolved form (whichever is easiest to pass). Unknown source names return false. A map without an ignoreList field returns false for every source.