[RickUsingGitHub]

Browser edits could overwrite later changes, and saved printer settings could roll back after reloading. Queue design changes and exports, persist printer settings from both modes and undo/redo, reject non-finite scalar inputs while preserving damaged-file recovery, and share closed-mesh export validation across desktop and web.

Add matching features through a shared Python workspace module:

• Surprise me locks for dimensions, silhouette, cross-section, twist and colours.
• Named printer and material profiles.
• A design library with silhouette thumbnails, favourites, 30 recovery snapshots, and portable JSON import/export.
• Requested/softened side-envelope comparison with maximum surface displacement.
• Five printable clearance-test socket/pin pairs (0.1–0.5 mm radial gaps).

The library is local to each app; export/import transfers it between desktop and web. Comparison shows side envelopes rather than a full 3D displacement view. Clearance samples are general fit coupons, not replicas of lid latches. README and UI describe these limits.

Validation:

• All 27 existing geometry/export tests passed together in GitHub Actions on the submitted commit.
• All 91 existing desktop UI checks passed using Qt offscreen.
• Seven new shared/desktop tests passed, including profile isolation, library round trips, locks, recovery, finite numbers, mesh export gates and calibration topology.
• Node regressions passed for delayed edits, colours, reload, undo/redo and replacement ordering.
• Final headless Chrome end-to-end check passed on the submitted version: initial build, printer persistence, library variant/favourite/profile/lock controls, comparison and sample export; no page errors.
• Python compilation, new-module linting, JavaScript syntax and git whitespace checks passed.

Add regression checks on pull requests and require shared checks before Pages deployment. This PR is intentionally a draft for review; it does not merge or deploy the changes.

Final verification: GitHub Actions run 42151357587 passed for b8f7e74. The final local Chrome check also passed on 7 November 2026 (Australia/Sydney).