The editing-data reader stopped on `Xk`/`XK` (global process colours) and
on `p`/`P` (pattern fills), so the file fell back to its PDF part, which has
only the top-level layers.
- `Xk`/`XK` read like `Xx`: a global swatch (not a spot ink), linked at its tint.
- `%AI3_BeginPattern` sections are read by a reader of their own into
pattern swatches (tile from `(name) llx lly urx ury`, art in pattern space);
`p`/`P` fill or stroke with them, placed by the operator's matrix. A pattern
it can't read whole still makes a fill with it unreadable, as before.
- Tests on synthetic editing data; fuzz tokens and fixture extended.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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