Transform: Align to Pixel Grid keeps an object's horizontal and vertical edges on the pixel grid

Squashed from #6169 onto main.

docs/mcp.md

@@ -3429,6 +3429,56 @@ Absolute target, so it leaves objects that already have that size as they are; r
 {"name":"run_command","arguments":{"command":"object.transformEach","params":{"relative":false,"scaleH":50,"scaleV":50}}}
 ```
 
+## Align to Pixel Grid
+
+`object.setPixelAligned {ids?|id?, on?}` turns the pixel-aligned property of the objects given (default: the selected
+objects) on or off (`on` defaults to true), as the Transform panel's Align to Pixel Grid checkbox does (described on
+the help page,
+<https://helpx.adobe.com/illustrator/desktop/get-started/learn-the-basics/pixel-preview-mode-for-web-graphics.html>).
+It returns `{ids}`, the objects whose property changed. While the property is on:
+
+- The object's horizontal and vertical straight segments sit on whole points, or on half points when a stroke centered
+  on the path has an odd weight, so that the stroke's edges fall on the pixel grid. A stroke that is hidden or has no
+  paint does not count. Its stroke weights are whole points, at least 1.
+- Every move, scale, rotation, reflection, shear, Transform Each, Align or Distribute move (of objects or of
+  direct-selected anchors), Transform panel change, move of direct-selected anchors or of one anchor
+  (`path.moveAnchor`), new anchors from `path.setAnchors`, live shape change (`object.setLiveShape`), move of a
+  compound path's path on its own, and artboard move or resize that carries the art (`artboard.move` with
+  `moveArt`, `artboard.setProps` with art, Rearrange Artboards) snaps those segments again, as do the art copies of `artboard.move` with `copy` and Duplicate
+  Artboards, the copies that `edit.duplicate` and the paste commands move, and `object.slice.move` of an object slice,
+  and so does every `stroke.set`, `stroke.weightUp` and `stroke.weightDown` edit, which also rounds the new weight. An
+  appearance edit that adds, removes, hides, repaints or reweighs a stroke snaps them again too:
+  `appearance.setItem`, `appearance.addStroke`, `appearance.removeItem`, `appearance.clear`,
+  `appearance.reduceToBasic`, `appearance.showAllHidden`, `appearance.transfer` (both objects), `appearance.copyFrom`
+  (the Eyedropper), `paint.setStroke` and `graphicStyle.apply`, in the same undo step as the edit, as is every member
+  of an active Global Edit that such an edit or move reaches. Every other command that changes a pixel-aligned object
+  (for example Object › Path › Average) snaps it again as part of its undo step. Each anchor that such a segment shares moves with its handles, so diagonal segments and curves keep their shape apart from those
+  anchors. A rotated shape with no horizontal or vertical segment is left as it is. Pixel-aligned art of a linked
+  opacity mask snaps when its object moves.
+- Coordinates that differ stay at least 1 pt apart within a subpath, so a narrow shape does not collapse. A
+  coordinate on a whole point snaps to the half point above it and one on a half point to the whole point below it, so
+  hiding and showing an odd stroke returns the path to where it was. A placed gradient and the art of a linked opacity
+  mask move with the snapped anchors, and so do pattern tiles when the move transforms patterns. A pixel-aligned member
+  of an Objects on Path group snaps again after the group places it on its path.
+- A live rectangle, polygon, line or pie is moved and scaled as a whole to the snapped bounds, and stays live. A full
+  ellipse has only curves and is left as it is. A path with Live Corners snaps the outline its corners are cut from and keeps
+  its Live Corners. A compound path snaps each of its paths with the compound path's stroke.
+- Make Compound Path from paths or compound paths that include a pixel-aligned one gives a pixel-aligned compound path
+  and snaps it; its paths do not keep the property, and a path inside a compound path cannot take it alone (an error).
+  Release Compound Path gives each released path the property of the compound path. A path pasted into a compound
+  path, alone or from a pasted compound path, drops its own property and snaps with the compound path.
+
+Turning the property on snaps the objects at once; turning it off keeps their geometry. These rules are VectorCraft's
+own: only paths and compound paths can be aligned, and type, images, groups, guides and other objects are an error
+that leaves the document as it was. The change is one undo step, and when every object already has the value nothing
+changes and no undo step is made. The property is saved in the native file (`pixel_aligned` in `document.node`), and
+files saved without it read back with it off.
+
+```json
+{"name":"run_command","arguments":{"command":"object.setPixelAligned","params":{"on":true}}}
+{"name":"run_command","arguments":{"command":"object.setPixelAligned","params":{"ids":[12],"on":false}}}
+```
+
 ## Live Corners
 
 `object.setLiveShape {id?, ids?, radius?, kind?, corners?, items?}` sets the corners of any path (one undo step): a live

docs/target-app-parity.md

@@ -711,6 +711,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
   - The History panel menu's Clear History (`edit.clearHistory`) removes every step to undo and to redo and leaves the document as it is; it is not an undo step itself, and it is disabled when there is no step to clear.
   - The New Document from State button at the bottom of the History panel (`edit.newDocumentFromState`) makes a new document, which becomes active, from the state the panel has selected ([public source](https://helpx.adobe.com/illustrator/desktop/get-started/learn-the-basics/undo-edits-and-manage-design-history.html)). VectorCraft's own rules: the new document takes the next Untitled-N name, is marked unsaved, has nothing selected and has no steps to undo or redo, and the source document and its steps stay as they are.
   - The Transform panel menu's Transform Object Only, Transform Pattern Only and Transform Both (`transformPanelPatterns`) choose whether the fields, flips and menu flips of the Transform panel and the Properties panel's Transform section move the object and leave its pattern tiles, move the tiles alone, or both (until a choice they follow General › Transform Pattern Tiles, as before); Use Registration Point for Symbol (`useRegistrationPointForSymbol`) measures and transforms one selected symbol instance from its symbol's registration point, where the instance's flips, rotations and shears put it ([Transform panel overview](https://helpx.adobe.com/illustrator/desktop/manage-objects/reshape-transform-objects/transform-panel-overview.html); `panels::transform::tests::the_menu_chooses_whether_the_object_its_pattern_or_both_transform`, `use_registration_point_for_symbol_measures_an_instance_from_its_registration_point`, `use_registration_point_for_symbol_follows_a_transformed_instance`, `tests_prefs::transform_panel_patterns_defaults_to_following_the_general_preference`).
+  - The Transform panel's Align to Pixel Grid checkbox (`object.setPixelAligned`) gives paths and compound paths a pixel-aligned property, saved in the native file: their horizontal and vertical straight segments sit on whole points (half points under an odd centered stroke) with whole stroke weights, and every move, scale, rotation, reflection, Transform Each, Align move, Transform panel change, move of direct-selected anchors or of one anchor, move of a compound path's path on its own, artboard move, resize or copy that carries the art, Duplicate or paste that moves a copy, stroke edit and appearance edit that adds, removes, hides, repaints or reweighs a stroke snaps them again, while diagonal segments and curves keep their shape; a compound path made from an aligned path or compound path is aligned and snaps its paths with its own stroke; the box shows a dash for a mixed selection and is unavailable for type, images and groups ([Pixel-aligned property](https://helpx.adobe.com/illustrator/desktop/get-started/learn-the-basics/pixel-preview-mode-for-web-graphics.html); `tests::pixelalign::turning_it_on_snaps_the_path_in_one_undo_step`, `it_stays_aligned_through_transforms`, `it_stays_aligned_when_its_artboard_moves`, `diagonal_segments_and_curves_keep_their_shape`, `type_and_images_cannot_be_aligned`, `the_property_is_saved_and_read_back`, `stroke_edits_keep_it_aligned`, `a_compound_path_of_aligned_paths_is_aligned`, `a_compound_path_of_an_aligned_compound_path_is_aligned`, `a_stroke_without_paint_snaps_to_whole_points`, `moving_direct_selected_anchors_keeps_it_aligned`, `moving_one_anchor_keeps_it_aligned`, `moving_a_path_of_an_aligned_compound_path_keeps_it_aligned`, `artboard_options_and_artboard_copies_keep_it_aligned`, `appearance_edits_keep_it_aligned`, `placed_gradients_follow_the_snapped_path`, `duplicates_and_pastes_keep_it_aligned`, `paths_added_to_or_moved_in_an_aligned_compound_path_keep_it_aligned`, `the_art_of_a_linked_opacity_mask_keeps_it_aligned`, `a_linked_opacity_mask_follows_a_snap`, `aligning_direct_selected_anchors_keeps_it_aligned`, `global_edit_keeps_its_members_aligned`, `a_path_with_live_corners_snaps_its_inner_edges`, `geometry_edits_keep_it_aligned`, `other_path_edits_keep_it_aligned`, `panels::transform::tests::align_to_pixel_grid_shows_and_sets_the_property`).
   - Object › Transform › Reset Bounding Box squares the box of every object inside the selected ones as well: the children of groups, compound paths, clip groups, blends, envelopes, repeats and intertwines, and the art of linked opacity masks. Ungroup and the release commands then bring back boxes square to the page (VectorCraft's own behavior; `bboxrotate::reset_bounding_box_squares_the_objects_inside_a_group`, `reset_bounding_box_squares_the_turned_members_of_a_square_group`, `reset_bounding_box_then_release_clipping_mask` and the other `reset_bounding_box_then_*` tests, `reset_bounding_box_leaves_the_art_of_an_unlinked_opacity_mask`).
   - Native macOS menu bar, vector tool cursors, a ⌘K command palette, middle-button panning with any tool. Native menus explicitly end tracking on command selection, outside window presses and Escape; menu updates wait until tracking ends, and a dismissing press never starts a canvas gesture (M14.8).
   - The errors of the blend spine commands (Move Spine Point, Reshape Spine Segment, Add Spine Point and Delete Spine Point) show in the status bar in the interface language: each has a row in every catalog that translates all status and error messages and in Bulgarian (`blend_spine_param_errors_are_translated`).