Artboards: an artboard's guide label colors its own guides

Each artboard can carry a guide label: one of the layer colors or a
custom RGB. Guides that belong to an artboard draw in its label color,
and guides without an artboard, or on an artboard without a label, keep
the guide color from the preferences. Selected guides still draw in the
selection color.

- Artboard Options has a Guide Label row (None, the layer colors with
  swatches, or Custom with a color swatch).
- artboard.new and artboard.setProps take guideLabel: null, a layer
  color's name, or #rrggbb. Any other value is an error. The inspect
  summary lists guideLabel when one is set.
- The native format saves the label and skips it when unset; a preset
  index outside the layer colors reads as no label.
- artboard.setProps no longer adds an undo step when nothing changes.

Docs: docs/mcp.md, docs/target-app-parity.md.

docs/mcp.md

@@ -4786,7 +4786,7 @@ value: true}`; the Control bar's and Properties' Scale Artwork with Artboard che
 Artboard) makes its handle drags proportional and passes `scaleArt`, as do Properties' and the Transform panel's
 artboard size fields while the tool is in use.
 
-`artboard.setProps {artboards: [{index, name?, color?, locked?, showCenterMark?, showCrossHairs?, showVideoSafeAreas?, videoRulerPixelAspectRatio?, x?, y?, width?, height?}…], scaleArt?, moveArt?, …}` sets several
+`artboard.setProps {artboards: [{index, name?, color?, guideLabel?, locked?, showCenterMark?, showCrossHairs?, showVideoSafeAreas?, videoRulerPixelAspectRatio?, x?, y?, width?, height?}…], scaleArt?, moveArt?, …}` sets several
 artboards in one undo step, each with its own fields; the other params apply to all of them. The art that moves or
 scales with each artboard is the art inside it before any of them changes, and an object inside several of them goes
 with the first one listed that moves or scales its art. An empty list and a list that names an artboard twice are
@@ -4920,6 +4920,20 @@ is the width of one video pixel over its height, which `view.videoRulers` counts
 the native format keep both (written only when on or not 1), and `inspect_document` adds `showVideoSafeAreas: true` and
 `videoRulerPixelAspectRatio` to an artboard that has them.
 
+Artboard Options' Guide Label: `artboard.setProps {index, guideLabel?: name | "#rrggbb" | null}` (or each entry of
+`artboards`) gives the artboard a guide label, and `artboard.new` takes one too. The canvas draws the artboard's own
+guides (`guide.add {artboard}`) in the label's color instead of the guide color preference, in the preference's style;
+canvas guides, guides of an artboard without a label and guides whose artboard is gone keep the preference's color, and
+selected guides are still drawn in the selection color. The value is a layer color's name, spelled exactly as Layer
+Options lists it (`"Light Blue"`, `"Red"`, …), or `#rrggbb`; null clears it, and new artboards and older files have none.
+The label is VectorCraft's own (no public documentation describes one): it is screen-only, so exports and print leave
+it out, the paper and the artboard's background color stay as they are, and a locked artboard's label can change.
+Anything else (a preset's index, another letter case, `#rrggbbaa`) is refused with "`guideLabel` is null, a layer
+color's name or #rrggbb", and a list with a bad value anywhere changes nothing. Duplicates and copies keep it, the
+native format writes it only when set (a preset index past the layer colors opens as none), and `inspect_document` adds
+`guideLabel` (the name or `#rrggbb`) to an artboard that has one. `artboard.setProps` adds no undo step when nothing it
+is given differs from the artboard.
+
 Artboard Options' Global checkboxes are application preferences, not artboard properties: `fadeRegionOutsideArtboard`
 (Fade Region Outside Artboard) and `artboardUpdateWhileDragging` (Update While Dragging), both on by default
 (`prefs.set {values: {fadeRegionOutsideArtboard: false}}`; also Edit › Preferences › General › Artboard Options). With

docs/target-app-parity.md

@@ -651,6 +651,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
 - **Rulers (#1212):** drag the intersection to preview and set a document zero point, or double-click it to reset to the active artboard's top-left. Transform, Properties and Control X/Y fields measure from it and convert entered positions back to absolute command coordinates. The origin survives every native format version and compression; geometry, guides and patterns stay in place. Public reference: [Use rulers](https://helpx.adobe.com/ca/illustrator/desktop/measure-and-align/grids-and-guides/use-rulers.html).
 - **Global and artboard rulers:** View › Rulers › Change to Global / Artboard Rulers (Cmd+Alt+R, `view.globalRulers`). A new document has artboard rulers: the rulers and the Transform, Properties, Control and Info X/Y count from the active artboard's top-left corner, or the zero point dragged out for that artboard, which moves with it; with global rulers one document zero point serves every artboard. Guide readouts and Shift ruler-tick snapping follow the same zero point. The mode is saved with the document; files from before it open with global rulers, as they measured. Regression tests: `engine/tests/it/ruler_origin.rs`, `ui-egui/src/tests/ruler_origin.rs`, `tools/src/rulerguide.rs`. Public reference: [About rulers](https://helpx.adobe.com/illustrator/desktop/measure-and-align/grids-and-guides/about-rulers.html).
 - **Video display options (#2849):** Artboard Options' Show Video Safe Areas and Video Ruler Pixel Aspect Ratio, and View › Rulers › Show Video Rulers ([Set video display options for artboards](https://helpx.adobe.com/illustrator/desktop/create-manage-artboards/organize-manage-artboards/set-video-display-options-for-artboards.html)). Each artboard has its own (`artboard.setProps`/`artboard.new` `showVideoSafeAreas`, `videoRulerPixelAspectRatio` 0.1–10, default 1), set in one undo step and written to the native format only when on or not 1, so other documents save byte for byte as before. The help page names the safe areas without numbers; our choice is [EBU R 95](https://tech.ebu.ch/docs/r/r095.pdf)'s (note 5): the canvas outlines the action-safe area 3.5% and the title-safe (graphics-safe) area 5% in from each edge, 1 point wide and turned with the view; exports and print leave them out. Show Video Rulers (`view.videoRulers`) shows the rulers counting the active artboard in pixels from its top-left corner, whatever the ruler origin: a pixel is as many points wide as the ratio and one point tall, so a 720 × 480 pt artboard at 0.9 reads 800 × 480. Hide Video Rulers returns them to the General unit; Shift ruler-tick snapping of new guides keeps the General unit. Regression tests: `tests/panelcmds.rs` (`artboard_video_display_options_*`, `artboard_display_marks_stay_out_of_exports`), `tests/docsetup.rs` (`an_artboard_shows_its_video_safe_areas`), `canvas.rs` (`video_rulers_count_the_artboard_in_pixels_of_its_aspect_ratio`), `tests/ruler_origin.rs` (`show_video_rulers_counts_the_active_artboard_in_pixels`), `dialogs/tests.rs` (`artboard_options_show_video_display_options`).
+- **Artboard guide labels (#6414, in part):** Artboard Options' Guide Label gives an artboard a color label (`artboard.setProps`/`artboard.new` `guideLabel`: a layer color's name, `#rrggbb` or null), and the canvas draws that artboard's own guides in it; canvas guides, guides of an unlabeled artboard and guides whose artboard is gone keep the guide color preference, and selected guides keep the selection color. The [help page](https://helpx.adobe.com/illustrator/desktop/measure-and-align/grids-and-guides/align-graphic-objects-with-guides.html) describes guides restricted to an artboard, not a label, so the label, its palette and the color precedence are VectorCraft's own. It is screen-only (exports and print leave it out), written to the native format only when set, kept by duplicates and copies, and changeable on a locked artboard; `artboard.setProps` adds no undo step when nothing changes. This VectorCraft addition does not raise a score. Regression tests: `tests/panelcmds.rs` (`artboard_guide_labels_are_set_and_cleared_in_one_undo_step`, `artboard_guide_labels_round_trip_through_the_native_format`), `doc` `tests.rs` (`guide_label_text_names_a_layer_color_or_rgb`, `artboard_guide_label_defaults_and_skips_in_json`), `canvas::tests` (`artboard_guide_label_colors_only_its_own_guides`), `dialogs/tests.rs` (`artboard_options_shows_sets_and_clears_the_guide_label`).
 - **Fade Region Outside Artboard:** Artboard Options' Global checkboxes Fade Region Outside Artboard and Update While Dragging ([user guide, Artboard options](https://web.archive.org/web/20210601162814/https://helpx.adobe.com/pdf/illustrator_reference.pdf)) are application preferences (`fadeRegionOutsideArtboard`, `artboardUpdateWhileDragging`), both on by default. While the Artboard tool is active the canvas draws everything outside the artboards, the pasteboard and the art on it, with each color channel at 60% of its value (VectorCraft's own amount), or only outside the box around all the artboards when crossing artboards would leave more than 4,096 rectangles in view; with Update While Dragging off it draws as usual during an artboard move or resize. Presentation Mode, exports and print do not change. Regression tests: `canvas::tests` (`the_artboard_tool_fades_the_pasteboard`, `presentation_mode_draws_no_fade`, `the_fade_darkens_art_on_the_pasteboard_and_not_on_the_artboard`, `outside_rects_cover_the_bounds_minus_the_boards`, `outside_rects_of_a_row_of_boards_stay_few`, `the_fade_of_crossing_boards_stays_bounded`, `update_while_dragging_keeps_or_drops_the_fade_during_an_artboard_drag`, `the_pasteboard_fade_leaves_exports_unchanged`), `dialogs/tests.rs` (`artboard_options_global_checkboxes_set_the_preferences`, `artboard_options_error_leaves_the_global_preferences_unchanged`).
 - **Saved views (G7):** View › New View… and Edit Views… ([public source](https://helpx.adobe.com/illustrator/using/viewing-artwork.html): up to 25 views per document, saved with it, renamed or deleted in Edit Views, chosen from the bottom of the View menu). Each view keeps the zoom, centre and rotation; the View menu lists all 25 (`view.goto1`–`view.goto25`), and Edit Views… lists them to rename or delete, applied together as one undo step. A file's views are checked when it opens (at most 25, unique names up to 255 characters, a finite centre and a positive zoom). Tests: `saved_views_round_trip_and_from_a_file_are_tidied` (`crates/format/tests/prop_format.rs`), `crates/engine/src/cmd/views.rs`, `crates/ui-egui/src/dialogs/edit_views.rs` and `every_saved_view_is_listed_at_the_bottom_of_the_view_menu` (`crates/ui-egui/src/menus.rs`).
 - **Window › Arrange › Tile (G7):** Tile (`window.arrange.tile`) shows every open document at once, edge to edge in the document area ([public source](https://helpx.adobe.com/illustrator/using/viewing-artwork.html)), one pane each in a grid of as many columns as the square root of the number of documents, rounded up, each fitted to its pane. The current document's pane is the canvas; the other panes draw their documents with their artboards, guides and selected objects, and a press in one makes its document the current one. Consolidate All Windows (`window.arrange.consolidateAllWindows`) shows one document under its tab again. The grid and when the two items are enabled (Tile with two documents or more, Consolidate All Windows while they are tiled) are VectorCraft's own. Tests: `crates/ui-egui/src/canvas/panes/tests.rs`.