Two editing actions
Paint changes a cell to the selected palette color. Progress mode toggles a completion mark while keeping its underlying color. Undo restores the previous state of the last edited cell.
Download after a session
The updated ZIP contains a fresh PDF, SVG, palette list and project JSON. The project is the editable source; import it next time to recover the cell colors and completion marks.
Browser tabs can be discarded or closed without warning. There is no account or automatic server backup, so save a project copy after meaningful edits and keep the original image separately.
Make a small save-and-reopen check
After opening a pattern, switch to Toggle completed stitch and click one cell. The status should increase by one. Download the updated chart pack, extract project.json, then choose Open a saved project and select that file. The completion count should survive the round trip. This small check confirms that you are reopening the edited project rather than an older download.
The project stores the palette, cell assignments and completed-cell indices. The chart PDF and SVG are regenerated from the current colors, while completion marks remain in the editable project. Do not expect a PDF printout to function as an editable progress database; retain the JSON when continuing digitally.
Separate checkpoints from experiments
Use distinct folders or filenames for an original conversion, a cleaned pattern and a stitching checkpoint. Undo keeps only the most recent 500 cell edits in the current session and does not survive a reload. If you change palette assignments halfway through a project, compare the new chart with already stitched areas before continuing. A completed mark records your decision, not an automatic camera inspection of the fabric.