Fix #651: a dual-GPU Mac falls back to its other GPU

Metal reports no PCI ids, so both GPUs of a dual-GPU Mac had the adapter key
Metal:0000:0000. When the integrated GPU failed at start-up, the restart left
out both and the app quit, although the discrete GPU works. An adapter without
ids is now keyed by its name, so the restart leaves out only the one that
failed.

The failure itself was wgpu's indirect-call validation compute shader, which
OCLP-patched Metal on an Iris Pro can't compile. Nothing in VectorCraft or
egui draws indirectly, so that validation is off (WGPU_VALIDATION_INDIRECT_CALL=1
turns it back on).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ROADMAP.md

@@ -4,7 +4,7 @@ VectorCraft is a clean-room, open-source, pure-Rust reimplementation of the Adob
 
 This file tracks **how far we are and what's left**. Time estimates are wall-clock hours of continuous Claude Opus 5.5 agent work (including builds and the CI gate), given both for **one agent** and for **4–6 parallel agents** on disjoint crates. They are counted from the remaining work (see [Parity estimate](#parity-estimate)), calibrated against measured throughput, and updated as work lands.
 
-_Last updated: 2026-10-09 (after placed documents (File › Place of a `.vectorcraft` file, linked), M4.14–M4.98, M8.1–M8.20, M14.4–M14.7, the MCP prompts, resource templates, completions and logging, the 2026-10-07 issue fixes, the Layers panel rework and the 2026-10-08 community contributions: Pen and shape-tool modifiers, path editing, Layers, Artboards, Swatches/Brushes and dialogs, Japanese composition and PDF text, Hebrew/Arabic type, interface languages (Spanish among them), the font menu, saved selections, MCP and EPS, the missing-font export warning (#319), open paths in the Shape Builder (#374), PDF/`.ai` import keeping strokes live and hidden and nested layers (#372), per-corner Live Corners (#381), SVG type opening at the size it draws at (#396), the Wayland clipboard with copied-file paste (#398), ruler guides that can be selected, moved and deleted (#414), two batches of Preferences options that were stored but unused (#394), skeleton reads with `document.find` for large documents over MCP (#416) and anchors dragged with Direct Selection snapping to points, segments and smart guides, clipped SVG layers opening as clipping layers (#420), PDF/`.ai` layers read on pages of tens of millions of operators (#419), Document Color Mode putting RGB greys on the black plate on request and converting pattern tiles (#421) and movable dialogs with Offset Path's Joins dropdown (#423) and numeric fields scrubbed by dragging their label (#400), stroke weight presets in the stroke unit (#426), the Appearance panel's Opacity popup (#430), type on a path brackets, flip and Type on a Path Options that keep the type in place (#429), Layers rows dragged with a ghost and dropped on the trash or New Layer (#435), tool flyouts opening on a right or corner press (#436), tool flyouts torn off into floating toolbars (#437), the Shape Builder's erase mode deleting edges too (#439), installed fonts registered outside the font folders and fonts installed while the app runs listed in the font menus (#443), alike circular corners on rectangles that aren't square (#442), tool cursors as OS cursors so the pointer no longer trails over the canvas (#444), artboards copied and pasted with their art (#446), guides dragged out of the rulers snapping to the art's side midpoints and the artboards, artboard guides (#451), the toolbar's double arrow and Window › Toolbars › Double Column switching between one and two columns in any window height (#455), the Smart Guides display options and Snapping Tolerance (#394), Font Size and Leading combo boxes with preset lists in the Character and Properties panels and the Control bar (#458), screenshots pasted from the clipboard on macOS, Windows and the web (#457), the Properties panel's Fill and Stroke matching the Control bar's, Illustrator's Window menu panel keys (Shift+F7 for Align…) and Alt-wheel zoom whatever the wheel preference (Discord feedback), the point/area type widget (Discord feedback), groups in legacy Illustrator .ai files (Discord feedback), a rotating desktop log file (#465), image controls in the Control bar and Properties panel: Image Trace with its presets, Mask, Crop Image, Embed/Unembed, and an Image Trace object's preset, Expand and Release (Discord feedback), the Pen working as the Anchor Point tool with Alt held over a selected path's handles and anchors, and anchor buttons that convert, connect and cut paths at the selected anchors (Discord feedback), Japanese hanging punctuation (burasagari, #463), Escape leaving Presentation Mode with no screen mode saved across restarts, documents dropped on the desktop app opening as tabs of their own and a note that an `.ai` file's art off its artboards isn't in the part read (#472), Add/Delete Anchor Point tool icons drawn from the Pen tool's (#479), EPS import running more of PostScript Level 3 (patterns, Type 3 fonts, mesh shadings, masked images, VM and resource probes), and a preview that stands in saying why (Discord feedback, #466, #469, #474), chords with modifiers recorded in Edit › Keyboard Shortcuts (#487), Type Object Selection by Path Only (#394), Anti-aliased Artwork (#394), Show Pixel Grid (#394), pen and touch taps pressed and lifted within one frame clicking where they tapped and the Linux/Wayland pen-tablet workaround (#491), bounding-box resizes landing on the other objects' anchors and centres with labels, and the Rotate, Scale, Shear and Reflect tools snapping their drags (#482), Shift-drag marquees that toggle the objects or anchors they reach and a Lasso whose Alt subtraction keeps the rest of the selection (#483), the mouse wheel stepping the focused numeric field, the dialogs' and preferences' drag values made such fields (#485), Show The Home Screen When No Documents Are Open (#394), Numbers Without Units Are Points (#394), Auto-Collapse Iconic Panels (#394), the Contextual Task Bar moved by its handle and its More Options menu pinning and resetting its position, a designed macOS DMG windoLine truncated
+_Last updated: 2026-10-09 (after placed documents (File › Place of a `.vectorcraft` file, linked), M4.14–M4.98, M8.1–M8.20, M14.4–M14.7, the MCP prompts, resource templates, completions and logging, the 2026-10-07 issue fixes, the Layers panel rework and the 2026-10-08 community contributions: Pen and shape-tool modifiers, path editing, Layers, Artboards, Swatches/Brushes and dialogs, Japanese composition and PDF text, Hebrew/Arabic type, interface languages (Spanish among them), the font menu, saved selections, MCP and EPS, the missing-font export warning (#319), open paths in the Shape Builder (#374), PDF/`.ai` import keeping strokes live and hidden and nested layers (#372), per-corner Live Corners (#381), SVG type opening at the size it draws at (#396), the Wayland clipboard with copied-file paste (#398), ruler guides that can be selected, moved and deleted (#414), two batches of Preferences options that were stored but unused (#394), skeleton reads with `document.find` for large documents over MCP (#416) and anchors dragged with Direct Selection snapping to points, segments and smart guides, clipped SVG layers opening as clipping layers (#420), PDF/`.ai` layers read on pages of tens of millions of operators (#419), Document Color Mode putting RGB greys on the black plate on request and converting pattern tiles (#421) and movable dialogs with Offset Path's Joins dropdown (#423) and numeric fields scrubbed by dragging their label (#400), stroke weight presets in the stroke unit (#426), the Appearance panel's Opacity popup (#430), type on a path brackets, flip and Type on a Path Options that keep the type in place (#429), Layers rows dragged with a ghost and dropped on the trash or New Layer (#435), tool flyouts opening on a right or corner press (#436), tool flyouts torn off into floating toolbars (#437), the Shape Builder's erase mode deleting edges too (#439), installed fonts registered outside the font folders and fonts installed while the app runs listed in the font menus (#443), alike circular corners on rectangles that aren't square (#442), tool cursors as OS cursors so the pointer no longer trails over the canvas (#444), artboards copied and pasted with their art (#446), guides dragged out of the rulers snapping to the art's side midpoints and the artboards, artboard guides (#451), the toolbar's double arrow and Window › Toolbars › Double Column switching between one and two columns in any window height (#455), the Smart Guides display options and Snapping Tolerance (#394), Font Size and Leading combo boxes with preset lists in the Character and Properties panels and the Control bar (#458), screenshots pasted from the clipboard on macOS, Windows and the web (#457), the Properties panel's Fill and Stroke matching the Control bar's, Illustrator's Window menu panel keys (Shift+F7 for Align…) and Alt-wheel zoom whatever the wheel preference (Discord feedback), the point/area type widget (Discord feedback), groups in legacy Illustrator .ai files (Discord feedback), a rotating desktop log file (#465), image controls in the Control bar and Properties panel: Image Trace with its presets, Mask, Crop Image, Embed/Unembed, and an Image Trace object's preset, Expand and Release (Discord feedback), the Pen working as the Anchor Point tool with Alt held over a selected path's handles and anchors, and anchor buttons that convert, connect and cut paths at the selected anchors (Discord feedback), Japanese hanging punctuation (burasagari, #463), Escape leaving Presentation Mode with no screen mode saved across restarts, documents dropped on the desktop app opening as tabs of their own and a note that an `.ai` file's art off its artboards isn't in the part read (#472), Add/Delete Anchor Point tool icons drawn from the Pen tool's (#479), EPS import running more of PostScript Level 3 (patterns, Type 3 fonts, mesh shadings, masked images, VM and resource probes), and a preview that stands in saying why (Discord feedback, #466, #469, #474), chords with modifiers recorded in Edit › Keyboard Shortcuts (#487), Type Object Selection by Path Only (#394), Anti-aliased Artwork (#394), Show Pixel Grid (#394), pen and touch taps pressed and lifted within one frame clicking where they tapped and the Linux/Wayland pen-tablet workaround (#491), bounding-box resizes landing on the other objects' anchors and centres with labels, and the Rotate, Scale, Shear and Reflect tools snapping their drags (#482), Shift-drag marquees that toggle the objects or anchors they reach and a Lasso whose Alt subtraction keeps the rest of the selection (#483), the mouse wheel stepping the focused numeric field, the dialogs' and preferences' drag values made such fields (#485), Show The Home Screen When No Documents Are Open (#394), Numbers Without Units Are Points (#394), Auto-Collapse Iconic Panels (#394), the Contextual Task Bar moved by its handle and its More Options menu pinning and resetting its position, a designed macOS DMG windoLine truncated
 
 ## Where we are
 
@@ -143,7 +143,7 @@ grade by behaviour against `plan/illustrator/`, not by whether a menu item exist
 - **Type:** Text Wrap, Type on a Path effects (Rainbow/Skew/3D Ribbon/Stair Step/Gravity) and Options (Flip, Align to Path, Spacing; OK keeps the type where it is), type on a path's start, centre and end brackets (Selection and Direct Selection drag them to set where the type runs, slide it along its path and, across the path, flip it: #429), Character and Paragraph Styles (override-preserving redefine), paragraph attributes per paragraph (alignment, indents, spacing, hyphenation, hanging punctuation, tab stops, paragraph style, direction, mojikumi and leading model; the Paragraph, Tabs and Paragraph Styles panels act on the paragraphs the Type tool's selection or caret touches, Return continues the paragraph's style, threads and SVG keep them), Area Type Options (rows/columns/inset/first baseline, vertical Align Top/Center/Bottom/Justify per row/column, reflowing non-rectangular frames and text wrap), threaded text across any closed shapes, Fit Headline, the Every-line Composer for justified and ragged text (paragraph-wide breaks for an even rag, Single-line per object from the Paragraph panel menu or `text.setFormat {composer}`). Area type resizes like Illustrator's type areas: a bounding-box handle drag (Selection tool) or Area Type Options Width/Height size the frame and the text reflows at its size (threads too); Direct Selection drags a frame corner or edge (`text.reshapeArea`). Point type still scales. Auto Size: the frame height follows the text after every edit, in the same undo step (rectangular frames of horizontal type in one row; columns get the least height that holds them; a height set by hand or threading turns it off), and the "Auto Size New Area Type" preference gives it to new area type. Shrink Text to Fit (beyond Illustrator): overflowing area type scales its sizes, leading and baseline shifts down by the largest factor (in 0.1 pt steps of the first run, down to a minimum percentage) that fits, at layout time so every export sees it. `text.areaOptions` and `document.inspect` report overflow and the shrink factor. The Selection tool shows the type widget beside selected type's bounding box (hollow on point type, filled on area type); double-clicking it converts between them (Type › Convert To Area Type / Convert To Point Type), keeping the text and its styles in place. Variable fonts list every named instance as a style of their family (Figtree Light to Black and their italics, Bahnschrift, Segoe UI Variable), and the instance chosen is shaped, drawn, outlined and measured at its axis settings; PDF and SVG embed it as that instance. Variation axis sliders are not done. Beyond Illustrator: inline graphics (`text.insertInline`, Type ▸ Insert Inline Symbol) set a document symbol in a run of type as one character that flows, wraps and justifies like a glyph (InDesign-style inline objects, e.g. mana symbols in card rules text): sized to a multiple of the font size, centred on the cap height, opening up tall lines, following Redefine Symbol; a character of its run's size for Character Alignment and Top-to-Top leading, placed by the bidi reordering in right-to-left text (a neutral U+FFFC); drawn on the canvas, kept as live text plus a `<use>` in SVG and as vector art in PDF; Backspace removes it whole. Hebrew and Arabic are laid out right to left with the Unicode bidirectional algorithm (embedded Latin and numbers keep their direction, lines put in visual order after wrapping) in point, area and path type, with caret, selection and arrow keys in visual order; each paragraph's direction comes from its first strong character unless Paragraph Direction sets it (Paragraph panel with Show Indic Options, `text.setFormat {direction}`), and new type aligns to the start of its direction. SVG export outlines right-to-left text. Font Size and Leading are combo boxes in the Character and Properties panels (Font Size in the Control bar too, beside the Character link, font family and style): type, step with ↑/↓ or the spinner, scrub the label, or pick a preset (6–72 pt, shown in the type unit; Leading also Auto), each pick one undo step; Kerning and Tracking list -100…200; a size, leading, kerning or tracking the selected text doesn't share shows blank (#458).
 - **Interface languages, vertical type:** VectorCraft ▸ Language (or Preferences ▸ User Interface) picks Automatic (the system locale) or a registered language, persisted as `interfaceLanguage`. Translations come from per-language catalogs (`i18n/*.tsv`): Traditional and Simplified Chinese, Japanese, Spanish (neutral international Spanish, for every `es-*` locale), French (every `fr-*` locale), Italian (every `it-*` locale) and Russian (every `ru-*` locale) cover the whole interface, Czech and Brazilian Portuguese every menu label, Brazilian Portuguese the shell's `tl!` literals too (tested); Spanish, French, Italian and Russian also translate status-bar and error messages as they are shown (`@msg` templates, every message literal tested; the messages themselves stay English for agents); untranslated text stays English. Japanese and Chinese glyphs come from the craft-fonts build input (release builds) or the installed fonts, Czech, Spanish, French, Italian and Russian ones from the bundled UI fonts. The web app follows the browser's languages (or `?lang=`). The Basic toolbar's Type button holds Vertical Type in its flyout. Vertical Type, Vertical Area Type and Vertical Type on a Path create vertical text (columns right to left, upright CJK glyphs and marks with `vert` alternates, Latin and longer numbers on their side, two- and three-digit numbers set as tate-chu-yoko in one em of the column (kept whole when justified), upright glyphs centred on the column (tracked or justified too), point type's anchor on the first column's centre line); kinsoku (the strict set) applies to horizontal and vertical Japanese, and justified Japanese lines spread their room between characters (not inside Latin words); Paragraph panel › Mojikumi Set (shown with Preferences › Type › Show East Asian Options, `text.setFormat {mojikumi}`): None or Line-end Punctuation Half Width (new type's default, as in Illustrator; older documents and imported text keep None) shares one half-em space between consecutive punctuation, sets a closing mark ending a line half width and an opening bracket starting a wrapped line flush with its start, and puts a quarter em between Japanese and Latin letters or digits; Paragraph panel menu › Top-to-Top / Bottom-to-Bottom Leading measures leading from em box top to top (area type's first line touches the frame) or from baseline to baseline (new type in a Japanese interface starts top to top, with em box centre character alignment, #432); Paragraph panel menu › Burasagari None / Regular / Force (`text.setFormat {burasagari: "none"|"standard"|"forced"}`) hangs an East Asian comma or full stop (、。，．､｡) ending an area type line outside it, Regular (new type's default) when it doesn't fit and Force always (the rest of the line then fills the measure; closing brackets and Latin punctuation don't hang); Character panel menu › Character Alignment (with the East Asian options; `text.setFormat` or `text.setRangeStyle {charAlign}`) lines characters smaller than the largest on their line up on the Roman baseline, the em box top/right, centre or bottom/left, or the ICF (ideographic character face) top/right or bottom/left, from the font's BASE table or, without one, the average ink box of some ideographs and kana; Type ▸ Type Orientation switches existing text; caret, selection, hit testing and arrow keys follow the writing direction. Vertical text exports to PDF as real text and to SVG as outlines.
 - **Transparency:** opacity masks (clip/invert/disable/link), exported as SVG `<mask>` and PDF soft masks.
-- **Advanced art:** live Blends (steps/distance/smooth colour, editable spine, anchor-targeted Blend tool, faithful interpolation, knockout), Envelope Distort (warp/mesh/top object, Reset, full Envelope Options, mesh handles, Edit Contents; type, images, symbols, gradients, patterns and appearance distorted everywhere), Liquify tools with options and pen pressure, Puppet Warp with rotating pins, Perspective Grid with presets, movable planes and projected type (choosing a perspective tool shows the grid; Hide Grid hides it with the tool still chosen), Gradient Mesh, Shape Builder (stroke-only open paths and lines cut the regions they cross and enclose regions of their own; filled open paths count as closed; erase mode while Alt/Option is held: a minus pointer, red highlights of what will go, a click or drag deletes the regions touched, the pieces of open lines and the edges (outline pieces between the points where paths meet, opening their paths there) it passes over, one undo step, `shapeBuilder.merge {erase}` and `shapeBuilder.regions` edges over MCP), Live Paint (every path an edge, open lines included), Image Trace (12 presets, colour layers traced in parallel; a trace past two million anchor points or an image over 64 megapixels is refused with advice rather than running out of memory, and a selection too large to outline shows its bounds (#525); Object › Image Trace › Make and Make and Expand trace at once with the Default preset, #543; with an image selected the Control bar and the Properties panel show Image Trace, whose arrow traces with any preset, Mask (`object.maskImage`: a clipping path on the image's outline, selected so its handles crop), Crop Image and Embed or Unembed in place of Fill and Stroke; with an Image Trace object selected, its Preset (choosing another traces again), View, the Image Trace panel and Expand, plus Release in Properties; the five View modes (Tracing Result, with Outlines, Outlines, Outlines with Source Image, Source Image) redraw a trace on screen without tracing again, are saved with it and `imageTrace.setView` sets them, while exports and Expand keep the result; the panel's Advanced section is a header that stays open or closed as it was left (part of #641); Palette (Full Tone, Automatic, Document Library) and Create Strokes are not done), pattern swatches with pattern editing mode, live Repeat (radial/grid/mirror).
+- **Advanced art:** live Blends (steps/distance/smooth colour, editable spine, anchor-targeted Blend tool, faithful interpolation, knockout), Envelope Distort (warp/mesh/top object, Reset, full Envelope Options, mesh handles, Edit Contents; type, images, symbols, gradients, patterns and appearance distorted everywhere), Liquify tools with options and pen pressure, Puppet Warp with rotating pins, Perspective Grid with presets, movable planes and projected type (choosing a perspective tool shows the grid; Hide Grid hides it with the tool still chosen), Gradient Mesh, Shape Builder (stroke-only open paths and lines cut the regions they cross and enclose regions of their own; filled open paths count as closed; erase mode while Alt/Option is held: a minus pointer, red highlights of what will go, a click or drag deletes the regions touched, the pieces of open lines and the edges (outline pieces between the points where paths meet, opening their paths there) it passes over, one undo step, `shapeBuilder.merge {erase}` and `shapeBuilder.regions` edges over MCP), Live Paint (every path an edge, open lines included), Image Trace (12 presets, colour layers traced in parallel; a trace past two million anchor points or an image over 64 megapixels is refused with advice rather than running out of memory, and a selection too large to outline shows its bounds (#525); Object › Image Trace › Make and Make and Expand trace at once with the Default preset, #543; with an image selected the Control bar and the Properties panel show Image Trace, whose arrow traces with any preset, Mask (`object.maskImage`: a clipping path on the image's outline, selected so its handles crop), Crop Image and Embed or Unembed in place of Fill and Stroke; with an Image Trace object selected, its Preset (choosing another traces again), View, the Image Trace panel and Expand, plus Release in Properties; the five View modes (Tracing Result, with Outlines, Outlines, Outlines with Source Image, Source Image) redraw a trace on screen without tracing again, are saved with it and `imageTrace.setView` sets them, while exports and Expand keep the result; the panel's Advanced section is a header that stays open or closed as it was left (part of #641); Color mode's Palette: Limited, Full Tone (as many colours as the tones need, Less … More), Automatic (flat art with its own colours, else Full Tone; a heuristic) and Document Library (the most used colours of the document's swatches or a swatch library, filled with the swatch colours as they are), part of #641; Advanced › Create: Fills and/or Strokes, where lines up to the Stroke width trace as stroked centre lines (distance transform, thinning, a skeleton graph with spurs pruned, curve fitting; one width per line; without Fills, wider areas become stroked outlines), part of #641), pattern swatches with pattern editing mode, live Repeat (radial/grid/mirror).
 - **Paint and appearance (M3):**
   - **Swatches:** names follow the colour model and are unique; Swatch Options (process/spot, Global, Gray/RGB/HSB/CMYK/Web, live preview); editing a global or spot swatch recolours every linked fill, stroke and text run in one undo step; multi-select and delete with confirmation; New Swatch and New Color Group dialogs (a group from the selected artwork's colours); swatches in colour groups convert, separate and count like any other. The Swatches panel selects ranges and whole groups, has a find field, and drags swatches to reorder, regroup or paint art; Add Used Colors, Select All Unused, Merge, Ungroup and Sort by Kind; a CMYK document keeps applied colours in CMYK. Swatch libraries: nine generated colour libraries and five gradient libraries in a library panel, saved as `.vcswatches`, `.gpl` or CSS, and loaded from `.vcswatches`, `.gpl` and swatch exchange (`.ase`) files (RGB, CMYK, Lab and Gray; global, spot and process; groups). Tints of global and spot colours ("Name 40%") stay linked and separate as a percentage of their plate. Spot colours can be defined in Lab (Spot Colors options). A built-in [Registration] swatch prints on every plate.
   - **Colour:** a Color Picker (colour field, H/S/B/R/G/B channel slider, HSB/RGB/Lab/CMYK fields, hex, web-only snapping, out-of-gamut correction); the Color panel follows each colour's own model and Alt-click paints the other proxy; proxies look through groups and show "?" for mixed paint; Invert, Complement, Apply Last Color (`,`) and Apply Last Gradient (`.`) keep the colour model; every paint command feeds the recent colours. The Color Guide has 21 harmony rules, Steps and Variation options and Limit to Library. Adjust Color Balance (its Global mode shifts tints) and Saturate preview live; Edit Colors and Recolor also reach meshes, images and patterns. Recolor Artwork has colour reduction, five recolour methods, presets, Limit to Library, a colour-wheel Edit tab and Edit Color Group; a local Color Themes panel saves five-colour themes. Fill/Stroke chips open swatch and mixer popovers (the Properties panel has the Control bar's Fill and Stroke chips, Stroke link and weight spinner, with nothing selected too), panels have Illustrator's Window menu keys (Align Shift+F7, Transform Shift+F8, Pathfinder Cmd+Shift+F9, Layers F7, Character Cmd+T…; every panel can be given one in Edit › Keyboard Shortcuts), and Eyedropper Options pick up and apply chosen attributes (Alt and Shift+Alt, image pixels). Fills and strokes can overprint (Attributes panel, Overprint Black options), and CMYK documents blend in inks on screen, in PDF and when flattening. Document Color Mode converts the art, symbols, pattern tiles and swatches through the colour settings: Gray stays Gray, RGB greys separate into four-colour greys and a rich black as Illustrator does, or go on the black plate only with `grays: "black"` (also for `document.open {colorMode}`).
@@ -215,7 +215,7 @@ about 1–1.5 agent-hours each, so the other rows (estimated on the older scale)
 | Type core | 9 | 80% | Middle Eastern features beyond bidi layout and Paragraph Direction (Character Direction, digit types, kashidas, the Middle Eastern composers, editable bidirectional SVG text, a split caret where directions meet); Hyphenation… and Justification… options (Every-line Composer for justified and ragged text, per object, is done; it is tuned by eye, not yet compared side by side with Illustrator; mixed type sizes in a paragraph still break single-line), Optical Margin Alignment, paragraph spacing limit for vertically justified area type, hidden characters, paragraph attributes in the Type tool's copy and paste (the characters keep their styles, the paragraphs take the destination's), mixed-value display in the Paragraph panel for a selection across differing paragraphs, Transform Again after a type-area resize (it scales the type), partial selection of type-area anchors by marquee | 14–19 |
 | Type advanced | 4 | 50% | CJK composition for vertical type (ruby, mojikumi beyond Line-end Punctuation Half Width — the other sets (and their paragraph-start bracket and indent rules), kinsoku sets and the Mojikumi Settings dialog —, proportional vertical metrics, manual tate-chu-yoko), variable font axis sliders (named instances are styles), tab leaders, spell check (open dictionary), Touch Type, Retype; vertical point/area/path type and Type Orientation have initial support (beyond parity, not scored: inline symbols in text) | 20–28 |
 | Symbols, blends, envelopes, Repeat, perspective | 5 | 88% | symbol libraries (original), dynamic symbols, envelope Anti-Alias/Preserve Shape output and warp point editing, brush interpolation in blends (M8 fidelity pass done) | 5–8 |
-| Image Trace, graphs, image tools | 3 | 70% | graph Design/Column/Marker, Create Object Mosaic, Crop Image polish (an on-canvas crop box), Image Trace Palette (Full Tone, Automatic, Document Library) and Create Strokes (Vector Halftone and the Image Trace View modes are done) | 6–10 |
+| Image Trace, graphs, image tools | 3 | 70% | graph Design/Column/Marker, Create Object Mosaic, Crop Image polish (an on-canvas crop box), per-feature stroke/fill choice and varying widths in Image Trace's Create Strokes (Vector Halftone and the Image Trace View modes, Palette and Create Strokes are done) | 6–10 |
 | Layers, artboards, document setup | 5 | 82% | Layers panel: a confirmation before deleting layers that hold art, Collect for Export, row context menus, the Layer Options dialog for several rows with mixed values, Paste Remembers Layers for sublayers, drag-scrolling a long panel while dragging rows; artboard presets/rearrange polish (Document Setup, New Document and the rest of the Layers panel are done) | 4–7 |
 | View & navigation | 3 | 70% | New View/Edit Views, multiple windows/arrange, Snap to Pixel/Glyph (print tiling is done) | 9–14 |
 | Guides, grids, smart guides, snapping, rulers | 3 | 84% | global/video rulers, Spacing Guides, Smart Guides' angle and distance readouts while drawing, Alt swapping a ruler guide's orientation, ruler guides selected together with art (marquee, Shift-click), ruler guides as Layers rows with their own lock and hide (#451: Lock Guides locks them all; Make Guides paths are Layers rows already) (dragging existing guides is done, #414; new guides snapping to side midpoints and artboards, and artboard guides, #451; the drawing tools snapping, with Construction Guides, #506) | 2–4 |

apps/vectorcraft/src/gpu.rs

@@ -22,8 +22,9 @@ use std::sync::{Arc, OnceLock};
 use eframe::egui_wgpu::NativeAdapterSelectorMethod;
 use eframe::wgpu::{self, Backend, DeviceType, PowerPreference};
 
-/// The adapters a restart leaves out, those the window failed on, as comma-separated
-/// `backend:vendor:device` keys (`Vulkan:1002:164e`). Set by the app itself when it starts again.
+/// The adapters a restart leaves out, those the window failed on, as comma-separated [`key`]s
+/// (`Vulkan:1002:164e`, `Metal:Intel Iris Pro Graphics`). Set by the app itself when it starts
+/// again.
 pub const SKIP_ENV: &str = "VECTORCRAFT_GPU_SKIP";
 
 /// wgpu's variable for choosing an adapter by (part of) its name, any case.
@@ -60,7 +61,7 @@ pub fn power_preference(pref: Option<&str>, env: Option<PowerPreference>) -> Pow
 /// One adapter, as [`adapter_order`] sees it.
 #[derive(Clone, Debug)]
 pub struct Candidate {
-    /// Identifies the adapter across a restart: `backend:vendor:device` ([`key`]).
+    /// Identifies the adapter across a restart ([`key`]).
     pub key: String,
     pub name: String,
     pub backend: Backend,
@@ -73,7 +74,7 @@ impl Candidate {
     fn new(adapter: &wgpu::Adapter, surface: Option<&wgpu::Surface<'_>>) -> Self {
         let info = adapter.get_info();
         Self {
-            key: key(info.backend, info.vendor, info.device),
+            key: key(info.backend, info.vendor, info.device, &info.name),
             presents: surface.is_none_or(|s| adapter.is_surface_supported(s)),
             name: info.name,
             backend: info.backend,
@@ -83,8 +84,15 @@ impl Candidate {
 }
 
 /// `backend:vendor:device`, e.g. `Vulkan:1002:164e` (PCI ids, as `MESA_VK_DEVICE_SELECT` takes them).
-fn key(backend: Backend, vendor: u32, device: u32) -> String {
-    format!("{backend:?}:{vendor:04x}:{device:04x}")
+/// Metal reports no ids (`0000:0000` for every GPU), so an adapter without them is `backend:name`
+/// (`Metal:Intel Iris Pro Graphics`): otherwise leaving out the one that failed would leave out
+/// every GPU of a dual-GPU Mac (#651). Commas, which separate [`SKIP_ENV`]'s keys, become spaces.
+fn key(backend: Backend, vendor: u32, device: u32, name: &str) -> String {
+    if vendor == 0 && device == 0 {
+        format!("{backend:?}:{}", name.replace(',', " ").trim())
+    } else {
+        format!("{backend:?}:{vendor:04x}:{device:04x}")
+    }
 }
 
 /// The order to try `candidates` in (their indices): only those that present to the window and
@@ -307,6 +315,27 @@ mod tests {
 
     /// A restart leaves out the adapter the window failed on, so Power Saving on the machine of
     /// #502 ends up on the NVIDIA GPU, and once every adapter failed there is nothing to try.
+    /// A dual-GPU Mac reports both GPUs under Metal with no PCI ids (#651): their keys still
+    /// differ, so when the integrated GPU fails, the restart renders on the discrete one.
+    #[test]
+    fn gpus_without_pci_ids_are_told_apart_by_name() {
+        let mac = |name: &str, device_type| Candidate {
+            key: key(Backend::Metal, 0, 0, name),
+            name: name.into(),
+            backend: Backend::Metal,
+            device_type,
+            presents: true,
+        };
+        let c = vec![mac("NVIDIA GeForce GT 750M", DeviceType::DiscreteGpu), mac("Intel Iris Pro Graphics", DeviceType::IntegratedGpu)];
+        assert_eq!((c[0].key.as_str(), c[1].key.as_str()), ("Metal:NVIDIA GeForce GT 750M", "Metal:Intel Iris Pro Graphics"));
+        let first = adapter_order(&c, PowerPreference::LowPower, None, &[]);
+        assert_eq!(names(&c, &first)[0], "Intel Iris Pro Graphics");
+        let skip = parse_skip(&c[first[0]].key);
+        assert_eq!(names(&c, &adapter_order(&c, PowerPreference::LowPower, None, &skip)), ["NVIDIA GeForce GT 750M"]);
+        // A comma in a name can't split the list.
+        assert_eq!(parse_skip(&key(Backend::Gl, 0, 0, "Mesa, llvmpipe")), ["Gl:Mesa  llvmpipe"]);
+    }
+
     #[test]
     fn a_restart_tries_the_next_adapter() {
         let c = issue_502();
@@ -433,8 +462,8 @@ mod tests {
     fn skipped_adapters_parse_from_a_comma_separated_list() {
         assert_eq!(parse_skip("Vulkan:1002:164e, Gl:10de:2f04,,"), ["Vulkan:1002:164e", "Gl:10de:2f04"]);
         assert!(parse_skip("").is_empty());
-        assert_eq!(key(Backend::Vulkan, 0x1002, 0x164e), "Vulkan:1002:164e");
-        assert_eq!(key(Backend::Gl, 0x10de, 0x2f04), "Gl:10de:2f04");
+        assert_eq!(key(Backend::Vulkan, 0x1002, 0x164e, "AMD Radeon"), "Vulkan:1002:164e");
+        assert_eq!(key(Backend::Gl, 0x10de, 0x2f04, "NVIDIA"), "Gl:10de:2f04");
     }
 
     #[test]

apps/vectorcraft/src/main.rs

@@ -423,6 +423,11 @@ fn main() -> std::process::ExitCode {
         // Only adapters that can show the window, in the order `gpu` gives (#306, #502).
         if let eframe::egui_wgpu::WgpuSetup::CreateNew(create) = &mut options.wgpu_options.wgpu_setup {
             create.native_adapter_selector = Some(gpu::selector(power, startup.clone()));
+            // Nothing draws or dispatches indirectly, so wgpu's check of indirect arguments only
+            // costs a compute shader at start-up, one some drivers can't compile (OCLP-patched
+            // Metal on an Iris Pro, #651). `WGPU_VALIDATION_INDIRECT_CALL=1` turns it back on.
+            create.instance_descriptor.flags =
+                (eframe::wgpu::InstanceFlags::from_build_config() - eframe::wgpu::InstanceFlags::VALIDATION_INDIRECT_CALL).with_env();
         }
         options
     };

crates/engine/src/cmd/buildcmds.rs

@@ -14,7 +14,7 @@ use std::sync::Arc;
 
 use serde_json::{Value, json};
 use vectorcraft_color::{Color, Paint};
-use vectorcraft_doc::appearance::{AppearanceItem, FillLayer, StrokeLayer};
+use vectorcraft_doc::appearance::{AppearanceItem, FillLayer, LineCap, LineJoin, StrokeLayer};
 use vectorcraft_doc::{Appearance, Document, Node, NodeId, NodeKind, Selection, TraceView};
 use vectorcraft_geom::{FillRule, PathData, Point, Rect, SubPath};
 use vectorcraft_pathops as po;
@@ -120,7 +120,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Make",
             ["Object", "Image Trace"],
             None,
-            "{id?: image or Image Trace group (default: selection), preset?: name (imageTrace.presets), params?: {mode: \"blackAndWhite\"|\"grayscale\"|\"color\", threshold: 0-255, colors: 2-256, paths: 0-100, corners: 0-100, noise: px, method: \"abutting\"|\"overlapping\", ignoreWhite, snapCurvesToLines}, view?: as imageTrace.setView (default: the traced object's own, else tracingResult)} → {id, paths, anchors, colors}",
+            "{id?: image or Image Trace group (default: selection), preset?: name (imageTrace.presets), params?: {mode: \"blackAndWhite\"|\"grayscale\"|\"color\", threshold: 0-255, palette: \"limited\"|\"fullTone\"|\"automatic\"|\"documentLibrary\" (color mode; limited: the `colors` best colours, fullTone: as many as the tones need, more with colorDetail, automatic: flat art with its own colours, else fullTone, documentLibrary: at most `colors` of the library's colours, as they are), colors: 2-256, colorDetail: 0-100 (fullTone, automatic), library: \"document\" (the document's swatches) or a swatch library id or name (swatch.library.list; documentLibrary), paths: 0-100, corners: 0-100, noise: px, method: \"abutting\"|\"overlapping\", ignoreWhite, snapCurvesToLines, fills: true, strokes: false (Create: lines up to strokeWidth wide become stroked centre lines; without fills, wider areas become stroked outlines), strokeWidth: px (10)}, view?: as imageTrace.setView (default: the traced object's own, else tracingResult)} → {id, paths, anchors, colors}",
             has_selection_or_ids,
             |s, p| trace_make(s, p, false)
         ),
@@ -664,7 +664,38 @@ fn trace_params(p: &Value) -> Result<tr::TraceParams> {
     for (k, val) in src {
         o.insert(k.clone(), val.clone());
     }
-    serde_json::from_value(v).map_err(|e| bad("imageTrace.make", e.to_string()))
+    let params: tr::TraceParams = serde_json::from_value(v).map_err(|e| bad("imageTrace.make", e.to_string()))?;
+    if !params.fills && !params.strokes {
+        return Err(bad("imageTrace.make", "Create needs fills, strokes or both"));
+    }
+    if !(params.stroke_width.is_finite() && params.stroke_width > 0.0) {
+        return Err(bad("imageTrace.make", "strokeWidth must be a positive number of pixels"));
+    }
+    Ok(params)
+}
+
+/// Document Library in Color mode: look the library's colours up into `params.swatches` → each
+/// one as traced (sRGB) with the colour to fill with.
+fn trace_library(s: &Session, params: &mut tr::TraceParams) -> Result<Vec<([u8; 3], Color)>> {
+    const C: &str = "imageTrace.make";
+    if params.mode != tr::Mode::Color || params.palette != tr::Palette::DocumentLibrary {
+        return Ok(vec![]);
+    }
+    let key = params.library.as_str();
+    let colors = super::swatchlib::library_colors(s, key)
+        .ok_or_else(|| bad(C, format!("no swatch library `{key}` (see swatch.library.list; \"document\": the document's swatches)")))?;
+    if colors.is_empty() {
+        return Err(bad(C, format!("`{key}` has no colours")));
+    }
+    let library: Vec<([u8; 3], Color)> = colors
+        .into_iter()
+        .map(|c| {
+            let [r, g, b, _] = c.to_rgba8(1.0);
+            ([r, g, b], c)
+        })
+        .collect();
+    params.swatches = library.iter().map(|l| l.0).collect();
+    Ok(library)
 }
 
 /// The most anchor points an Image Trace may make: a photo traced at high fidelity can make
@@ -674,7 +705,7 @@ pub const MAX_TRACE_ANCHORS: usize = 2_000_000;
 
 fn trace_make(s: &mut Session, p: &Value, expand: bool) -> Result<Value> {
     const C: &str = "imageTrace.make";
-    let params = trace_params(p)?;
+    let mut params = trace_params(p)?;
     let view = view_param(C, p)?;
     let params_json = serde_json::to_value(&params).map_err(|e| EngineError::Other(e.to_string()))?;
     // The preset's name if the parameters are exactly that preset's, else "Custom".
@@ -704,11 +735,14 @@ fn trace_make(s: &mut Session, p: &Value, expand: bool) -> Result<Value> {
     };
     let blob = s.doc()?.doc.images.get(&img.key).ok_or_else(|| EngineError::Other(format!("image data `{}` is missing", img.key)))?;
     let raster = tr::Raster::decode(&blob.bytes).map_err(|e| EngineError::Other(e.to_string()))?;
+    let library = trace_library(s, &mut params)?;
     let res = tr::trace_within(&raster, &params, MAX_TRACE_ANCHORS).map_err(|e| EngineError::Other(e.to_string()))?;
     // Pixel space of the decoded raster → the image object's pixel space → document.
     let sx = img.width.max(1) as f64 / raster.width.max(1) as f64;
     let sy = img.height.max(1) as f64 / raster.height.max(1) as f64;
     let xf = img.xf * vectorcraft_geom::Affine::scale_non_uniform(sx, sy);
+    // Document units per raster pixel (stroke widths).
+    let unit = xf.determinant().abs().sqrt();
     let (npaths, anchors, colors) = (res.paths.len(), res.anchor_count(), res.palette.len());
     let label = if expand { "Image Trace (Make and Expand)" } else { "Image Trace" };
     let id = s.edit(label, |d, sel| {
@@ -731,7 +765,21 @@ fn trace_make(s: &mut Session, p: &Value, expand: bool) -> Result<Value> {
         for tp in res.paths {
             let path = tp.path.transformed(xf);
             let mut n = shape_node(d, path, None);
-            n.appearance = fill_only(Paint::solid(Color::rgb8(tp.color[0], tp.color[1], tp.color[2])));
+            // A library colour fills with the swatch's own colour (its model kept).
+            let color = library.iter().find(|(rgb, _)| *rgb == tp.color).map_or_else(|| Color::rgb8(tp.color[0], tp.color[1], tp.color[2]), |l| l.1);
+            let paint = Paint::solid(color);
+            n.appearance = match tp.stroke {
+                // Traced lines: round ends and corners, as drawn lines have.
+                Some(width) => Appearance {
+                    items: vec![AppearanceItem::Stroke(StrokeLayer {
+                        cap: LineCap::Round,
+                        join: LineJoin::Round,
+                        ..StrokeLayer::new(paint, width * unit)
+                    })],
+                    ..Default::default()
+                },
+                None => fill_only(paint),
+            };
             children.push(Arc::new(n));
         }
         let gid = d.alloc_id();

crates/engine/src/cmd/swatchlib.rs

@@ -276,11 +276,18 @@ pub const DOCUMENT_SWATCHES: &str = "document";
 /// [`DOCUMENT_SWATCHES`], of the active document's swatches and colour groups. `None` when there is
 /// no such library (or document).
 pub fn limit_palette(s: &Session, key: &str) -> Option<Palette> {
+    Some(Palette::new(library_colors(s, key)?))
+}
+
+/// The solid colours of library `key` (an id or name) or, for [`DOCUMENT_SWATCHES`], of the
+/// active document's swatches and colour groups. `None` when there is no such library (or
+/// document).
+pub fn library_colors(s: &Session, key: &str) -> Option<Vec<Color>> {
     let colors = |sw: &Swatch| sw.paint.color();
     if key == DOCUMENT_SWATCHES {
-        return Some(Palette::new(s.active()?.doc.swatches_iter().filter_map(colors)));
+        return Some(s.active()?.doc.swatches_iter().filter_map(colors).collect());
     }
-    Some(Palette::new(library(s, key)?.1.iter().filter_map(colors)))
+    Some(library(s, key)?.1.iter().filter_map(colors).collect())
 }
 
 /// The `limitTo` parameter's palette ([`limit_palette`]); `None` without one (or for "").

crates/engine/src/tests_build.rs

@@ -4,7 +4,7 @@ use std::sync::Arc;
 
 use serde_json::{Value, json};
 use vectorcraft_color::{Color, Paint};
-use vectorcraft_doc::{ImageBlob, ImageObject, Node, NodeKind};
+use vectorcraft_doc::{AppearanceItem, ImageBlob, ImageObject, LineCap, LineJoin, Node, NodeKind};
 use vectorcraft_geom::{Affine, FillRule, PathData, Rect};
 use vectorcraft_tools::{Mods, PointerEvent, PointerKind};
 
@@ -669,6 +669,82 @@ fn image_trace_make_and_expand_and_color_presets() {
     assert!(s.execute("imageTrace.make", &json!({"params": {"mode": "rainbow"}})).is_err());
 }
 
+#[test]
+fn image_trace_palettes_and_swatch_libraries() {
+    let mut s = session();
+    let quads = vectorcraft_trace::Raster::from_fn(60, 60, |x, y| match (x < 30, y < 30) {
+        (true, true) => [230, 20, 20, 255],
+        (false, true) => [20, 200, 30, 255],
+        (true, false) => [20, 30, 220, 255],
+        (false, false) => [250, 230, 10, 255],
+    });
+    add_image(&mut s, &quads, Affine::IDENTITY);
+    let fills = |s: &Session, id: &Value| -> Vec<Color> {
+        traced_paths(&node(s, NodeId(id.as_u64().unwrap()))).iter().filter_map(|n| n.appearance.fill_paint().color()).collect()
+    };
+    // Document Library: every fill is one of the document's swatch colours, as it is.
+    let r = s.execute("imageTrace.make", &json!({"preset": "6 Colors", "params": {"palette": "documentLibrary"}})).unwrap();
+    let doc = crate::cmd::swatchlib::library_colors(&s, "document").unwrap();
+    let got = fills(&s, &r["id"]);
+    assert!(!got.is_empty() && got.iter().all(|c| doc.contains(c)), "{got:?}");
+    let t = node(&s, NodeId(r["id"].as_u64().unwrap())).trace.unwrap();
+    assert_eq!((t["params"]["palette"].as_str(), t["params"]["library"].as_str()), (Some("documentLibrary"), Some("document")));
+    assert!(t["params"].get("swatches").is_none(), "looked up again at every trace");
+    // A swatch library by id: the web-safe colours.
+    let r = s
+        .execute(
+            "imageTrace.make",
+            &json!({"id": r["id"], "preset": "6 Colors", "params": {"palette": "documentLibrary", "library": "web-safe-216", "colors": 3}}),
+        )
+        .unwrap();
+    let got = fills(&s, &r["id"]);
+    assert!((1..=3).contains(&got.len()), "{got:?}");
+    assert!(got.iter().all(|c| c.to_rgba8(1.0)[..3].iter().all(|v| v % 51 == 0)), "{got:?}");
+    // Full Tone and Automatic keep the four flat colours.
+    let mut id = r["id"].clone();
+    for palette in ["fullTone", "automatic"] {
+        let r = s.execute("imageTrace.make", &json!({"id": id, "preset": "6 Colors", "params": {"palette": palette, "colorDetail": 50}})).unwrap();
+        assert_eq!(r["colors"], 4, "{palette}");
+        id = r["id"].clone();
+    }
+    let mut bad = |p: Value| s.execute("imageTrace.make", &json!({"preset": "6 Colors", "params": p})).is_err();
+    assert!(bad(json!({"palette": "documentLibrary", "library": "No Such Library"})));
+    assert!(bad(json!({"palette": "rainbow"})));
+}
+
+#[test]
+fn image_trace_create_strokes_makes_stroked_centre_lines() {
+    let mut s = session();
+    // A 3 px wide horizontal line from x = 10 to 90 at y = 50, placed at 2× from (100, 100).
+    let r =
+        vectorcraft_trace::Raster::from_fn(100, 100, |x, y| if (10..90).contains(&x) && (49..52).contains(&y) { [0, 0, 0, 255] } else { [255; 4] });
+    add_image(&mut s, &r, Affine::translate((100.0, 100.0)) * Affine::scale(2.0));
+    let res = s.execute("imageTrace.make", &json!({"params": {"ignoreWhite": true, "strokes": true, "strokeWidth": 5}})).unwrap();
+    assert_eq!(res["paths"], 1);
+    let g = NodeId(res["id"].as_u64().unwrap());
+    let paths = traced_paths(&node(&s, g));
+    let line = &paths[0];
+    assert!(line.appearance.fill_paint().color().is_none(), "not filled");
+    let st = line.appearance.items.iter().find_map(|i| if let AppearanceItem::Stroke(st) = i { Some(st) } else { None }).expect("stroked");
+    assert!((st.width - 6.0).abs() < 1.0, "3 px at 2× is about 6 pt: {}", st.width);
+    assert_eq!((st.cap, st.join), (LineCap::Round, LineJoin::Round));
+    assert_eq!(st.paint, Paint::solid(Color::rgb8(0, 0, 0)));
+    let sp = &line.path_data().unwrap().subpaths[0];
+    assert!(!sp.closed);
+    let (a, b) = (sp.anchors[0].p, sp.anchors[sp.anchors.len() - 1].p);
+    assert!((a.y - 201.0).abs() < 1.5 && (b.y - 201.0).abs() < 1.5 && (a.x - b.x).abs() > 140.0, "{a:?} … {b:?}");
+    let t = node(&s, g).trace.unwrap();
+    assert_eq!((t["params"]["strokes"].as_bool(), t["params"]["strokeWidth"].as_f64()), (Some(true), Some(5.0)));
+    // Expand keeps the stroked line.
+    s.execute("imageTrace.expand", &json!({})).unwrap();
+    assert!(node(&s, g).children().unwrap()[0].appearance.items.iter().any(|i| matches!(i, AppearanceItem::Stroke(_))));
+    // Create needs Fills or Strokes, and a stroke width.
+    s.execute("edit.undo", &json!({})).unwrap();
+    for p in [json!({"fills": false, "strokes": false}), json!({"strokes": true, "strokeWidth": 0}), json!({"strokeWidth": -3})] {
+        assert!(s.execute("imageTrace.make", &json!({"id": g.0, "params": p})).is_err(), "{p}");
+    }
+}
+
 #[test]
 fn image_trace_presets_query_and_errors() {
     let mut s = session();

crates/engine/src/tests_xform.rs

@@ -247,10 +247,13 @@ fn artboard_tool_moves_with_art_creates_and_deletes() {
     assert_eq!(s.doc().unwrap().doc.artboards.len(), 2);
     assert_eq!(s.tool_options()["active"], 1);
     assert_eq!(s.doc().unwrap().doc.artboards[1].rect, Rect::new(1000.0, 0.0, 1200.0, 100.0));
-    // Delete it.
+    // Delete it: the tool takes the key ahead of the Clear shortcut (the UI only hands Delete to a
+    // tool that claims it).
+    assert!(s.tool_claims_key(ToolKey::Delete, ViewInfo::default()));
     s.tool_key(ToolKey::Delete, Mods::default(), ViewInfo::default()).unwrap();
     assert_eq!(s.doc().unwrap().doc.artboards.len(), 1);
-    // The last artboard can't be deleted.
+    // The last artboard can't be deleted, so Delete stays the shortcut's.
+    assert!(!s.tool_claims_key(ToolKey::Delete, ViewInfo::default()));
     s.tool_key(ToolKey::Delete, Mods::default(), ViewInfo::default()).unwrap();
     assert_eq!(s.doc().unwrap().doc.artboards.len(), 1);
 }

crates/mcp/src/prompts.rs

@@ -295,8 +295,12 @@ with the {effect} effect.
 Method:
 1. open_file the image: it becomes a document of its own pixel size.
 2. imageTrace.make with the preset name, adjusting `params` — mode blackAndWhite, grayscale or
-   color, then threshold, colors, paths, corners, noise, method abutting or overlapping,
-   ignoreWhite, snapCurvesToLines. Run imageTrace.presets to see every preset with its numbers.
+   color (palette limited, fullTone for photos, automatic, or documentLibrary to trace with
+   the document's swatches or a swatch `library`), then threshold, colors (colorDetail for
+   fullTone and automatic), paths, corners, noise, method abutting or overlapping,
+   ignoreWhite, snapCurvesToLines; for line art, strokes: true (with strokeWidth, the widest
+   line in pixels) traces lines as stroked centre lines instead of filled outlines. Run
+   imageTrace.presets to see every preset with its numbers.
    Lower paths and higher corners give the clean, logo-like result; high fidelity needs paths
    near 90. imageTrace.setView {view: \"outlinesWithSourceImage\"} draws the traced outlines
    over the image on screen to compare them (screenshots show it; exports keep the result).

crates/tools/src/xform/artboard.rs

@@ -259,10 +259,19 @@ impl Tool for ArtboardTool {
         }
     }
 
+    /// Delete/Backspace remove the active artboard ahead of the Clear shortcut, which would only
+    /// delete selected art; with one artboard left (it can't be deleted) they stay the shortcut's.
+    fn claims_key(&self, cx: &ToolContext, key: ToolKey) -> bool {
+        matches!(key, ToolKey::Delete | ToolKey::Backspace)
+            && self.drag.is_none()
+            && cx.doc.artboards.len() > 1
+            && self.active < cx.doc.artboards.len()
+    }
+
     fn key(&mut self, cx: &ToolContext, key: ToolKey, _mods: Mods) -> Vec<Action> {
         match key {
-            ToolKey::Delete | ToolKey::Backspace if self.drag.is_none() => {
-                if cx.doc.artboards.len() <= 1 || self.active >= cx.doc.artboards.len() {
+            ToolKey::Delete | ToolKey::Backspace => {
+                if !self.claims_key(cx, key) {
                     return vec![];
                 }
                 let i = self.active;
@@ -522,7 +531,8 @@ mod tests {
         let a = t.pointer(&cx, &ev(PointerKind::Up, 1100.0, 1050.0));
         assert_eq!(a[0], Action::Exec("artboard.new".into(), json!({"x": 1000.0, "y": 1000.0, "width": 100.0, "height": 50.0})));
         assert_eq!(a[1], Action::Notify("created".into()));
-        // Delete removes the active artboard.
+        // Delete removes the active artboard, ahead of the Clear shortcut.
+        assert!(t.claims_key(&cx, ToolKey::Delete) && t.claims_key(&cx, ToolKey::Backspace));
         assert_eq!(t.key(&cx, ToolKey::Delete, Mods::default()), vec![Action::Exec("artboard.delete".into(), json!({"index": 1}))]);
         assert_eq!(t.key(&cx, ToolKey::Escape, Mods::default()), vec![Action::SwitchTool("selection".into())]);
     }

crates/trace/src/centerline.rs

@@ -0,0 +1,379 @@
+//! Create Strokes: the parts of a colour layer no wider than the Stroke width, traced as stroked
+//! centre lines instead of filled outlines.
+//!
+//! 1. **Distance**: a chamfer (3-4) distance transform gives each pixel its distance to the nearest
+//!    pixel outside the layer.
+//! 2. **Lines**: an 8-connected component whose widest point (twice its largest distance, less
+//!    one) is within the stroke width is a line; wider ones stay filled areas.
+//! 3. **Skeleton**: the line is thinned to one pixel (Zhang–Suen, applied pixel by pixel so it
+//!    keeps its topology and two-pixel-wide lines don't vanish), then staircase corners that
+//!    don't connect anything are dropped.
+//! 4. **Graph**: runs of skeleton pixels between ends and junctions (touching junction pixels
+//!    merged into one point) become polylines through the pixel centres; rings without ends
+//!    become closed ones. Short spurs that thinning leaves at junctions are pruned and the runs
+//!    on either side of a junction left with two of them are joined.
+//! 5. **Curves**: each polyline is fitted like an outline ([`fit::fit_polyline`]); the stroke
+//!    width is the line's mean width (its pixel count over its length).
+
+use std::collections::HashSet;
+
+use vectorcraft_geom::{PathData, Point};
+
+use crate::fit::{self, FitOptions};
+
+/// One line of a colour layer: its centre lines and the width to stroke them with.
+pub(crate) struct Line {
+    pub path: PathData,
+    /// Stroke width in pixels.
+    pub width: f64,
+    pub pixels: usize,
+}
+
+/// The lines of colour `label` in `labels` (`w` × `h`, row-major) no wider than `max_width`
+/// pixels, and which pixels they cover (to leave out of the filled areas).
+pub(crate) fn lines(labels: &[u16], label: u16, w: usize, h: usize, max_width: f64, o: &FitOptions) -> (Vec<bool>, Vec<Line>) {
+    let mut thin = vec![false; labels.len()];
+    let mut out = vec![];
+    if w == 0 || h == 0 || labels.len() != w * h {
+        return (thin, out);
+    }
+    let mask = |i: usize| labels.get(i) == Some(&label);
+    let dt = distance(&mask, w, h);
+    let mut seen = vec![false; w * h];
+    let mut stack = vec![];
+    for start in 0..w * h {
+        if !mask(start) || seen[start] {
+            continue;
+        }
+        let mut comp = vec![];
+        seen[start] = true;
+        stack.push(start);
+        while let Some(i) = stack.pop() {
+            comp.push(i);
+            for j in neighbours(i, w, h) {
+                if mask(j) && !seen[j] {
+                    seen[j] = true;
+                    stack.push(j);
+                }
+            }
+        }
+        let widest = 2.0 * f64::from(comp.iter().map(|&i| dt[i]).max().unwrap_or(0)) / 3.0 - 1.0;
+        if widest > max_width {
+            continue;
+        }
+        let Some(line) = trace_line(&comp, w, max_width, o) else { continue };
+        for &i in &comp {
+            thin[i] = true;
+        }
+        out.push(line);
+    }
+    (thin, out)
+}
+
+/// The 8 neighbours of pixel `i` inside the `w` × `h` image.
+fn neighbours(i: usize, w: usize, h: usize) -> impl Iterator<Item = usize> {
+    let (x, y) = ((i % w) as i64, (i / w) as i64);
+    const AROUND: [(i64, i64); 8] = [(-1, -1), (0, -1), (1, -1), (-1, 0), (1, 0), (-1, 1), (0, 1), (1, 1)];
+    AROUND.into_iter().filter_map(move |(dx, dy)| {
+        let (nx, ny) = (x + dx, y + dy);
+        (nx >= 0 && ny >= 0 && nx < w as i64 && ny < h as i64).then(|| ny as usize * w + nx as usize)
+    })
+}
+
+/// Chamfer 3-4 distance (3 per pixel step, saturating) of each pixel in `mask` to the nearest
+/// pixel outside it; outside the image counts as outside.
+fn distance(mask: &impl Fn(usize) -> bool, w: usize, h: usize) -> Vec<u16> {
+    let mut d = vec![0u16; w * h];
+    let at = |d: &[u16], x: i64, y: i64| {
+        if x < 0 || y < 0 || x >= w as i64 || y >= h as i64 { 0 } else { d.get(y as usize * w + x as usize).copied().unwrap_or(0) }
+    };
+    for y in 0..h {
+        for x in 0..w {
+            let i = y * w + x;
+            if mask(i) {
+                let (x, y) = (x as i64, y as i64);
+                let steps = [(x - 1, y, 3), (x - 1, y - 1, 4), (x, y - 1, 3), (x + 1, y - 1, 4)];
+                d[i] = steps.iter().map(|&(nx, ny, c)| at(&d, nx, ny).saturating_add(c)).min().unwrap_or(0);
+            }
+        }
+    }
+    for y in (0..h).rev() {
+        for x in (0..w).rev() {
+            let i = y * w + x;
+            if mask(i) {
+                let (xi, yi) = (x as i64, y as i64);
+                let steps = [(xi + 1, yi, 3), (xi + 1, yi + 1, 4), (xi, yi + 1, 3), (xi - 1, yi + 1, 4)];
+                let v = steps.iter().map(|&(nx, ny, c)| at(&d, nx, ny).saturating_add(c)).min().unwrap_or(0);
+                d[i] = d[i].min(v);
+            }
+        }
+    }
+    d
+}
+
+/// A grid around one line: its pixels with a one-pixel empty border.
+struct Grid {
+    on: Vec<bool>,
+    w: usize,
+    h: usize,
+    /// Image position of grid pixel (0, 0).
+    x0: i64,
+    y0: i64,
+}
+
+impl Grid {
+    /// The 8 neighbours (N, NE, E, SE, S, SW, W, NW) of interior pixel `i`.
+    fn ring(&self, i: usize) -> [bool; 8] {
+        let w = self.w;
+        let g = |j: usize| self.on.get(j).copied().unwrap_or(false);
+        [g(i - w), g(i - w + 1), g(i + 1), g(i + w + 1), g(i + w), g(i + w - 1), g(i - 1), g(i - w - 1)]
+    }
+    fn interior(&self) -> impl Iterator<Item = usize> + use<> {
+        let (w, h) = (self.w, self.h);
+        (1..h.saturating_sub(1)).flat_map(move |y| (1..w.saturating_sub(1)).map(move |x| y * w + x))
+    }
+    fn neighbours(&self, i: usize) -> impl Iterator<Item = usize> + '_ {
+        let w = self.w;
+        [i - w, i - w + 1, i + 1, i + w + 1, i + w, i + w - 1, i - 1, i - w - 1].into_iter().filter(|&j| self.on.get(j).copied().unwrap_or(false))
+    }
+    fn degree(&self, i: usize) -> usize {
+        self.neighbours(i).count()
+    }
+    /// The centre of pixel `i` in image coordinates.
+    fn centre(&self, i: usize) -> Point {
+        Point::new((self.x0 + (i % self.w) as i64) as f64 + 0.5, (self.y0 + (i / self.w) as i64) as f64 + 0.5)
+    }
+}
+
+/// Zhang–Suen thinning. Each sub-iteration picks the pixels to remove from the same state, so the
+/// skeleton stays centred; they are then removed one by one, each only if it still doesn't
+/// disconnect anything, so a two-pixel-wide line thins to one pixel instead of vanishing.
+fn thin(g: &mut Grid) {
+    let removable = |p: &[bool; 8]| {
+        let b = p.iter().filter(|v| **v).count();
+        let a = (0..8).filter(|&k| !p[k] && p[(k + 1) % 8]).count();
+        (2..=6).contains(&b) && a == 1
+    };
+    let mut picked = vec![];
+    loop {
+        let mut changed = false;
+        for step in 0..2 {
+            picked.clear();
+            for i in g.interior() {
+                if !g.on[i] {
+                    continue;
+                }
+                let p = g.ring(i);
+                let (n, e, s, w) = (p[0], p[2], p[4], p[6]);
+                let side = if step == 0 { !(e && s && (n || w)) } else { !(n && w && (e || s)) };
+                if side && removable(&p) {
+                    picked.push(i);
+                }
+            }
+            for &i in &picked {
+                if removable(&g.ring(i)) {
+                    g.on[i] = false;
+                    changed = true;
+                }
+            }
+        }
+        if !changed {
+            break;
+        }
+    }
+    // Staircase corners: a pixel whose neighbours stay connected without it (Yokoi's
+    // 8-connectivity number 1) and that doesn't end the line.
+    loop {
+        let mut changed = false;
+        for i in g.interior() {
+            if !g.on[i] || g.degree(i) < 2 {
+                continue;
+            }
+            let p = g.ring(i);
+            // x1 = E, x2 = NE, x3 = N, x4 = NW, x5 = W, x6 = SW, x7 = S, x8 = SE.
+            let x = [p[2], p[1], p[0], p[7], p[6], p[5], p[4], p[3]];
+            let off = |k: usize| !x[k % 8];
+            let c8: usize = [0, 2, 4, 6].iter().map(|&k| usize::from(off(k)) - usize::from(off(k) && off(k + 1) && off(k + 2))).sum();
+            if c8 == 1 {
+                g.on[i] = false;
+                changed = true;
+            }
+        }
+        if !changed {
+            break;
+        }
+    }
+}
+
+/// A run of skeleton pixels between two nodes (`None`: none, a ring).
+#[derive(Clone)]
+struct Run {
+    pts: Vec<Point>,
+    ends: [Option<usize>; 2],
+    closed: bool,
+}
+
+impl Run {
+    fn length(&self) -> f64 {
+        self.pts.windows(2).map(|p| p[0].distance(p[1])).sum::<f64>()
+            + if self.closed { self.pts.first().zip(self.pts.last()).map_or(0.0, |(a, b)| a.distance(*b)) } else { 0.0 }
+    }
+}
+
+/// The centre lines of one line component (pixel indices of the `w`-wide image).
+fn trace_line(comp: &[usize], w: usize, max_width: f64, o: &FitOptions) -> Option<Line> {
+    let xs = comp.iter().map(|&i| i % w);
+    let ys = comp.iter().map(|&i| i / w);
+    let (x0, x1, y0, y1) = (xs.clone().min()?, xs.max()?, ys.clone().min()?, ys.max()?);
+    let (gw, gh) = (x1 - x0 + 3, y1 - y0 + 3);
+    let mut g = Grid { on: vec![false; gw * gh], w: gw, h: gh, x0: x0 as i64 - 1, y0: y0 as i64 - 1 };
+    for &i in comp {
+        g.on[(i / w - y0 + 1) * gw + (i % w - x0 + 1)] = true;
+    }
+    thin(&mut g);
+    let skeleton: Vec<usize> = g.interior().filter(|&i| g.on[i]).collect();
+    if skeleton.len() < 2 {
+        return None;
+    }
+    // Nodes: line ends, and junctions with the junction pixels touching them.
+    let mut node = vec![usize::MAX; g.on.len()];
+    let mut centres: Vec<Point> = vec![];
+    for &i in &skeleton {
+        let d = g.degree(i);
+        if d == 2 || node[i] != usize::MAX {
+            continue;
+        }
+        let id = centres.len();
+        let mut members = vec![i];
+        node[i] = id;
+        if d > 2 {
+            let mut k = 0;
+            while let Some(&p) = members.get(k) {
+                k += 1;
+                for q in g.neighbours(p).collect::<Vec<_>>() {
+                    if node[q] == usize::MAX && g.degree(q) > 2 {
+                        node[q] = id;
+                        members.push(q);
+                    }
+                }
+            }
+        }
+        let sum = members.iter().fold(Point::ZERO, |s, &m| s + g.centre(m).to_vec2());
+        centres.push(Point::new(sum.x / members.len() as f64, sum.y / members.len() as f64));
+    }
+    // Runs from each node, then the rings left.
+    let mut used: HashSet<(usize, usize)> = HashSet::new();
+    let edge = |a: usize, b: usize| (a.min(b), a.max(b));
+    let mut runs: Vec<Run> = vec![];
+    for &p in skeleton.iter().filter(|&&i| node[i] != usize::MAX) {
+        for q in g.neighbours(p).collect::<Vec<_>>() {
+            if node[q] == node[p] || !used.insert(edge(p, q)) {
+                continue;
+            }
+            let mut pts = vec![centres[node[p]], g.centre(q)];
+            let (mut prev, mut cur) = (p, q);
+            while node[cur] == usize::MAX {
+                let Some(next) = g.neighbours(cur).find(|&n| n != prev && !used.contains(&edge(cur, n))) else { break };
+                used.insert(edge(cur, next));
+                pts.push(g.centre(next));
+                (prev, cur) = (cur, next);
+            }
+            let end = (node[cur] != usize::MAX).then_some(node[cur]);
+            if let (Some(e), Some(last)) = (end, pts.last_mut()) {
+                *last = centres[e];
+            }
+            runs.push(Run { pts, ends: [Some(node[p]), end], closed: false });
+        }
+    }
+    for &s in &skeleton {
+        if node[s] != usize::MAX || g.neighbours(s).any(|n| used.contains(&edge(s, n))) {
+            continue;
+        }
+        let mut pts = vec![g.centre(s)];
+        let (mut prev, mut cur) = (usize::MAX, s);
+        let mut closed = false;
+        while let Some(next) = g.neighbours(cur).find(|&n| n != prev && !used.contains(&edge(cur, n))) {
+            used.insert(edge(cur, next));
+            if next == s {
+                closed = true;
+                break;
+            }
+            pts.push(g.centre(next));
+            (prev, cur) = (cur, next);
+        }
+        runs.push(Run { pts, ends: [None, None], closed });
+    }
+    // The line's mean width: its pixels over its length (the skeleton stops about half a width
+    // short of each end).
+    let width = |runs: &[Run]| {
+        let length: f64 = runs.iter().map(Run::length).sum();
+        let px = comp.len() as f64;
+        ((-length + (length * length + 4.0 * px).sqrt()) / 2.0).clamp(1.0, max_width.max(1.0))
+    };
+    let spur = width(&runs);
+    let runs = join(prune(runs, centres.len(), spur), centres.len());
+    let width = width(&runs);
+    let subs: Vec<_> = runs.iter().filter_map(|r| fit::fit_polyline(&r.pts, r.closed, o)).collect();
+    if subs.is_empty() {
+        return None;
+    }
+    Some(Line { path: PathData::new(subs), width, pixels: comp.len() })
+}
+
+/// The runs without the spurs thinning leaves: runs shorter than the line's `width` from a line end
+/// to a junction that keeps at least two other runs.
+fn prune(runs: Vec<Run>, nodes: usize, width: f64) -> Vec<Run> {
+    let mut degree = vec![0usize; nodes];
+    for e in runs.iter().flat_map(|r| r.ends.iter().flatten()) {
+        degree[*e] += 1;
+    }
+    let mut order: Vec<usize> = (0..runs.len()).collect();
+    order.sort_by(|a, b| runs[*a].length().total_cmp(&runs[*b].length()));
+    let mut keep = vec![true; runs.len()];
+    for i in order {
+        let r = &runs[i];
+        let [Some(a), Some(b)] = r.ends else { continue };
+        let (tip, fork) = if degree[a] == 1 { (a, b) } else { (b, a) };
+        if degree[tip] == 1 && degree[fork] >= 3 && r.length() < width.max(2.0) {
+            keep[i] = false;
+            degree[tip] -= 1;
+            degree[fork] -= 1;
+        }
+    }
+    runs.into_iter().zip(keep).filter_map(|(r, k)| k.then_some(r)).collect()
+}
+
+/// The runs joined through every node exactly two of them meet at (a run meeting itself closes).
+fn join(runs: Vec<Run>, nodes: usize) -> Vec<Run> {
+    let mut runs: Vec<Option<Run>> = runs.into_iter().map(Some).collect();
+    for n in 0..nodes {
+        let at: Vec<(usize, usize)> = runs
+            .iter()
+            .enumerate()
+            .flat_map(|(i, r)| r.iter().flat_map(move |r| (0..2).filter(move |&k| r.ends[k] == Some(n)).map(move |k| (i, k))))
+            .collect();
+        let [(i, ki), (j, kj)] = at[..] else { continue };
+        if i == j {
+            if let Some(r) = runs[i].as_mut() {
+                r.pts.pop();
+                r.ends = [None, None];
+                r.closed = r.pts.len() >= 3;
+            }
+            continue;
+        }
+        let (Some(mut a), Some(mut b)) = (runs[i].take(), runs[j].take()) else { continue };
+        // a ends at n, b starts at n.
+        if ki == 0 {
+            a.pts.reverse();
+            a.ends.reverse();
+        }
+        if kj == 1 {
+            b.pts.reverse();
+            b.ends.reverse();
+        }
+        a.pts.extend(b.pts.into_iter().skip(1));
+        a.ends[1] = b.ends[1];
+        runs[i] = Some(a);
+    }
+    runs.into_iter().flatten().collect()
+}

crates/trace/src/fit.rs

@@ -133,6 +133,49 @@ pub(crate) fn fit_loop(l: &Loop, o: &FitOptions) -> Option<SubPath> {
     Some(sp)
 }
 
+/// Fit a centre line through `pts` (pixel-centre points in order) into a Bézier subpath: the
+/// points within `polygon_tol` of it are dropped (Douglas–Peucker), then curves are fitted. A
+/// `closed` line runs back to its first point.
+pub(crate) fn fit_polyline(pts: &[Point], closed: bool, o: &FitOptions) -> Option<SubPath> {
+    let n = pts.len();
+    let first = *pts.first()?;
+    if n < 2 {
+        return None;
+    }
+    let mut ext = pts.to_vec();
+    let mut keep = vec![false; n + 1];
+    keep[0] = true;
+    if closed {
+        // Split the ring at its first point and the point farthest from it.
+        ext.push(first);
+        let far = (1..n).max_by(|&i, &j| pts[i].distance_squared(first).total_cmp(&pts[j].distance_squared(first))).unwrap_or(n / 2);
+        keep[far] = true;
+        rdp(&ext, 0, far, o.polygon_tol, &mut keep);
+        rdp(&ext, far, n, o.polygon_tol, &mut keep);
+    } else {
+        keep[n - 1] = true;
+        rdp(&ext, 0, n - 1, o.polygon_tol, &mut keep);
+    }
+    let mut poly: Vec<Point> = (0..n).filter(|&i| keep[i]).map(|i| pts[i]).collect();
+    if closed && poly.len() < 3 {
+        poly = pts.to_vec();
+    }
+    if poly.len() < if closed { 3 } else { 2 } {
+        return None;
+    }
+    let sp = SubPath::polyline(&poly, closed);
+    let fitted =
+        simplify_with(&PathData::single(sp), &SimplifyOptions { tolerance: o.fit_tol, corner_angle_deg: o.corner_angle, straight_lines: false });
+    let mut sp = fitted.subpaths.into_iter().next()?;
+    if sp.anchors.len() < 2 {
+        return None;
+    }
+    if o.snap_lines {
+        snap_to_lines(&mut sp, (o.fit_tol * 2.0).max(1.5));
+    }
+    Some(sp)
+}
+
 /// Retract the handles of curves that stay within `tol` of their chord.
 fn snap_to_lines(sp: &mut SubPath, tol: f64) {
     let n = sp.anchors.len();

crates/trace/src/lib.rs

@@ -4,8 +4,11 @@
 //! and classic colour quantisation), not from any existing implementation:
 //!
 //! 1. **Quantise** the image into a small palette: a luminance threshold (Black and White), 1-D
-//!    k-means over the luminance histogram (Grayscale), or median cut followed by weighted
-//!    k-means over a 15-bit colour histogram (Color). Transparent pixels are left out.
+//!    k-means over the luminance histogram (Grayscale), or, in Color, over a 15-bit colour
+//!    histogram as the [`Palette`] asks: median cut to a colour count followed by weighted k-means
+//!    (Limited), median cut until every colour box is tight (Full Tone), one of those two by
+//!    whether the image is flat art (Automatic), or the most used colours of a swatch library
+//!    (Document Library). Transparent pixels are left out.
 //! 2. **Remove noise**: 4-connected same-colour components smaller than `noise` pixels are merged
 //!    into their most common neighbouring colour.
 //! 3. **Follow boundaries**: for each colour layer, the pixel-crack edges between inside and
@@ -18,10 +21,15 @@
 //! 5. **Curves**: the polygon is fitted with cubic Béziers (`vectorcraft_pathops::simplify_with`,
 //!    least squares with corner detection); optionally nearly-straight curves snap to lines.
 //!
+//! With **Create: Strokes**, the parts of a colour layer no wider than the stroke width are traced
+//! as stroked centre lines instead (see `centerline`); without Fills, wider parts become stroked
+//! outlines.
+//!
 //! Colour layers are traced either *abutting* (each colour's own area; shapes share edges) or
 //! *overlapping* (stacked: each layer also covers every layer above it, so no hairline gaps).
 #![forbid(unsafe_code)]
 
+mod centerline;
 mod contour;
 mod fit;
 mod mosaic;
@@ -34,7 +42,7 @@ use vectorcraft_geom::PathData;
 
 pub use contour::{Component, Loop, trace_mask};
 pub use mosaic::mosaic;
-pub use quantize::{Quantized, TRANSPARENT, denoise, quantize};
+pub use quantize::{FULL_TONE_MAX, Quantized, TRANSPARENT, denoise, quantize};
 
 /// Errors decoding a raster.
 #[derive(Debug, thiserror::Error)]
@@ -132,6 +140,28 @@ pub enum Method {
     Overlapping,
 }
 
+/// Where Color mode's colours come from (the Palette popup).
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub enum Palette {
+    /// The `colors` colours that best represent the image.
+    #[default]
+    #[serde(alias = "Limited")]
+    Limited,
+    /// As many colours as the image's tones need, up to [`FULL_TONE_MAX`] (photos, gradients):
+    /// `color_detail` sets how close two colours may be and stay apart.
+    #[serde(alias = "Full Tone")]
+    FullTone,
+    /// Flat art (a few colours cover nearly all of it) traces with exactly those colours, anything
+    /// else as Full Tone.
+    #[serde(alias = "Automatic")]
+    Automatic,
+    /// The most used colours of a swatch library ([`TraceParams::swatches`]), at most `colors` of
+    /// them, exactly as they are.
+    #[serde(alias = "library", alias = "Document Library")]
+    DocumentLibrary,
+}
+
 /// Image Trace parameters (the Image Trace panel).
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 #[serde(default, rename_all = "camelCase")]
@@ -139,8 +169,20 @@ pub struct TraceParams {
     pub mode: Mode,
     /// Black and White: pixels darker than this (luminance 0–255) are black.
     pub threshold: u8,
-    /// Palette size for Color, number of grays for Grayscale (2–256).
+    /// Color: where the colours come from.
+    pub palette: Palette,
+    /// Palette size for Color (Limited; at most this many for Document Library), number of grays
+    /// for Grayscale (2–256).
     pub colors: u32,
+    /// Full Tone and Automatic: how many colours, 0 (few) – 100 (many).
+    pub color_detail: f64,
+    /// Document Library: the swatch library, `"document"` (the document's swatches) or a library id
+    /// or name. The caller looks its colours up into `swatches`.
+    pub library: String,
+    /// Document Library: the library's colours (sRGB). Not saved: they are looked up from
+    /// `library` at every trace.
+    #[serde(skip)]
+    pub swatches: Vec<[u8; 3]>,
     /// Paths (fidelity) 0–100: higher follows the pixels more tightly.
     pub paths: f64,
     /// Corners 0–100: higher keeps more corners.
@@ -152,6 +194,12 @@ pub struct TraceParams {
     pub ignore_white: bool,
     /// Replace nearly-straight curves with straight lines.
     pub snap_curves_to_lines: bool,
+    /// Create: trace areas as filled shapes.
+    pub fills: bool,
+    /// Create: trace lines no wider than `stroke_width` as stroked centre lines.
+    pub strokes: bool,
+    /// Stroke: the widest feature (px) traced as a stroke.
+    pub stroke_width: f64,
 }
 
 impl Default for TraceParams {
@@ -160,13 +208,20 @@ impl Default for TraceParams {
         Self {
             mode: Mode::BlackAndWhite,
             threshold: 128,
+            palette: Palette::Limited,
             colors: 6,
+            color_detail: 50.0,
+            library: "document".into(),
+            swatches: vec![],
             paths: 50.0,
             corners: 75.0,
             noise: 25,
             method: Method::Abutting,
             ignore_white: false,
             snap_curves_to_lines: false,
+            fills: true,
+            strokes: false,
+            stroke_width: 10.0,
         }
     }
 }
@@ -250,7 +305,8 @@ pub fn presets() -> Vec<(&'static str, TraceParams)> {
     PRESET_NAMES.iter().filter_map(|n| Some((*n, preset(n)?))).collect()
 }
 
-/// One traced shape: an outer contour plus its holes, filled with `color`.
+/// One traced shape: an outer contour plus its holes, filled with `color`, or (with `stroke`)
+/// lines stroked with it.
 #[derive(Clone, Debug, PartialEq)]
 pub struct TracedPath {
     /// In pixel coordinates (x right, y down; the image spans `0..width × 0..height`).
@@ -258,6 +314,9 @@ pub struct TracedPath {
     pub color: [u8; 3],
     /// Filled pixel count of the component the path came from.
     pub pixels: usize,
+    /// Create Strokes: the path is stroked this wide (px), not filled (centre lines, or the
+    /// outlines of wider areas without Fills).
+    pub stroke: Option<f64>,
 }
 
 /// The traced result, bottom-most path first.
@@ -357,15 +416,37 @@ impl Layers<'_> {
         let (params, opts) = (self.params, &self.opts);
         let color = *self.q.palette.get(ci)?;
         let overlapping = params.method == Method::Overlapping;
+        let (w, h) = (self.w, self.h);
+        // Create Strokes: this colour's lines, left out of its areas.
+        let (thin, lines) = if params.strokes {
+            centerline::lines(&self.q.labels, u16::try_from(ci).unwrap_or(TRANSPARENT), w, h, params.stroke_width, opts)
+        } else {
+            (vec![], vec![])
+        };
         let mask: Vec<bool> = self
             .q
             .labels
             .iter()
-            .map(|&l| l != TRANSPARENT && if overlapping { self.rank.get(l as usize).is_some_and(|&lr| lr >= r) } else { l as usize == ci })
+            .enumerate()
+            .map(|(i, &l)| {
+                l != TRANSPARENT
+                    && !thin.get(i).copied().unwrap_or(false)
+                    && if overlapping { self.rank.get(l as usize).is_some_and(|&lr| lr >= r) } else { l as usize == ci }
+            })
             .collect();
+        // Without Fills, areas are outlined with a 1 px stroke.
+        let area_stroke = (params.strokes && !params.fills).then_some(1.0);
         let min_hole = params.noise.max(1) as i64;
         let mut paths = vec![];
-        for comp in trace_mask(&mask, self.w, self.h) {
+        let mut add = |path: PathData, pixels: usize, stroke: Option<f64>| {
+            let n = path.anchor_count();
+            if self.anchors.fetch_add(n, Ordering::Relaxed).saturating_add(n) > self.max_anchors {
+                return false;
+            }
+            paths.push(TracedPath { path, color, pixels, stroke });
+            true
+        };
+        for comp in trace_mask(&mask, w, h) {
             let Some(outer) = fit::fit_loop(&comp.outer, opts) else { continue };
             let mut subs = vec![outer];
             for hole in &comp.holes {
@@ -374,12 +455,14 @@ impl Layers<'_> {
                 }
                 subs.extend(fit::fit_loop(hole, opts));
             }
-            let path = PathData::new(subs);
-            let n = path.anchor_count();
-            if self.anchors.fetch_add(n, Ordering::Relaxed).saturating_add(n) > self.max_anchors {
+            if !add(PathData::new(subs), comp.pixels, area_stroke) {
+                return None;
+            }
+        }
+        for line in lines {
+            if !add(line.path, line.pixels, Some(line.width)) {
                 return None;
             }
-            paths.push(TracedPath { path, color, pixels: comp.pixels });
         }
         Some(paths)
     }

crates/trace/src/quantize.rs

@@ -1,6 +1,6 @@
 //! Colour reduction and noise removal.
 
-use crate::{Mode, Raster, TraceParams};
+use crate::{Mode, Palette, Raster, TraceParams};
 
 /// Label of a transparent (untraced) pixel.
 pub const TRANSPARENT: u16 = u16::MAX;
@@ -67,10 +67,8 @@ pub fn quantize(img: &Raster, params: &TraceParams) -> Quantized {
                     b.sum[2] += p[2] as u64;
                 }
             }
-            let used: Vec<(usize, [f64; 3], f64)> =
-                bins.iter().enumerate().filter(|(_, b)| b.n > 0).map(|(i, b)| (i, b.mean(), b.n as f64)).collect();
-            let k = params.colors.clamp(2, 256) as usize;
-            let centers = kmeans_rgb(&used, k);
+            let used: Vec<Used> = bins.iter().enumerate().filter(|(_, b)| b.n > 0).map(|(i, b)| (i, b.mean(), b.n as f64)).collect();
+            let centers = color_palette(&used, params);
             let mut lut = vec![0u16; 1 << 15];
             for (i, c, _) in &used {
                 lut[*i] = nearest_rgb(&centers, *c) as u16;
@@ -187,12 +185,108 @@ fn nearest_rgb(centers: &[[f64; 3]], c: [f64; 3]) -> usize {
     best.1
 }
 
-/// Median cut for the initial palette, then weighted k-means refinement over histogram bins.
-fn kmeans_rgb(used: &[(usize, [f64; 3], f64)], k: usize) -> Vec<[f64; 3]> {
+/// The most colours Full Tone (and Automatic on continuous-tone images) makes.
+pub const FULL_TONE_MAX: usize = 256;
+
+/// A histogram bin in use: its index, mean colour and pixel count.
+type Used = (usize, [f64; 3], f64);
+
+/// Color mode's palette for the histogram bins `used`, as `params.palette` asks.
+fn color_palette(used: &[Used], params: &TraceParams) -> Vec<[f64; 3]> {
+    let k = params.colors.clamp(2, 256) as usize;
+    let detail = (params.color_detail / 100.0).clamp(0.0, 1.0);
+    // Full Tone: split until no colour box is wider than 96 (few colours) … 8 (many) levels per
+    // channel, which is one histogram bin.
+    let full_tone = || refine(used, centers(&median_cut(used, FULL_TONE_MAX, 96.0 - 88.0 * detail)));
+    match params.palette {
+        Palette::Limited => kmeans_rgb(used, k),
+        Palette::FullTone => full_tone(),
+        Palette::Automatic => match flat_colors(used, detail) {
+            Some(n) => kmeans_rgb(used, n),
+            None => full_tone(),
+        },
+        Palette::DocumentLibrary if !params.swatches.is_empty() => library_colors(used, &params.swatches, k),
+        // No library colours to use: as Limited.
+        Palette::DocumentLibrary => kmeans_rgb(used, k),
+    }
+}
+
+/// Automatic: how many colours flat art is made of, or `None` for continuous tone (photos,
+/// gradients). Flat art has most of its pixels in a few tight colours (anti-aliased edges and
+/// noise aside): the bins holding 90% of the pixels are few, and each colour's pixels sit mostly
+/// in one bin. `detail` (0–1) lets smaller colour areas count as colours of their own.
+fn flat_colors(used: &[Used], detail: f64) -> Option<usize> {
+    let total: f64 = used.iter().map(|u| u.2).sum();
+    if total <= 0.0 {
+        return Some(2);
+    }
+    let mut by_count: Vec<&Used> = used.iter().collect();
+    by_count.sort_by(|a, b| b.2.total_cmp(&a.2));
+    let mut covered = 0.0;
+    let main = by_count
+        .iter()
+        .take_while(|u| {
+            let before = covered;
+            covered += u.2;
+            before < 0.9 * total
+        })
+        .count();
+    if main > FLAT_BINS {
+        return None;
+    }
+    let boxes = median_cut(used, 64, 24.0);
+    let min_share = (0.04 - 0.035 * detail) * total;
+    let colours: Vec<&ColorBox> = boxes.iter().filter(|b| b.weight >= min_share).collect();
+    let weight: f64 = colours.iter().map(|b| b.weight).sum();
+    let peaks: f64 = colours.iter().map(|b| b.peak).sum();
+    (weight >= 0.9 * total && peaks >= 0.5 * weight && colours.len() <= 32).then_some(colours.len().max(2))
+}
+
+/// The most histogram bins flat art's main colours spread over (a few bins per colour).
+const FLAT_BINS: usize = 96;
+
+/// Document Library: the `k` swatches (at most) that the most pixels are nearest to.
+fn library_colors(used: &[Used], swatches: &[[u8; 3]], k: usize) -> Vec<[f64; 3]> {
+    let mut all: Vec<[f64; 3]> = vec![];
+    for s in swatches {
+        let c = s.map(f64::from);
+        if !all.contains(&c) {
+            all.push(c);
+        }
+    }
+    let mut weight = vec![0.0; all.len()];
+    for (_, c, n) in used {
+        if let Some(w) = weight.get_mut(nearest_rgb(&all, *c)) {
+            *w += n;
+        }
+    }
+    let mut order: Vec<usize> = (0..all.len()).collect();
+    order.sort_by(|a, b| weight[*b].total_cmp(&weight[*a]).then(a.cmp(b)));
+    order.into_iter().take(k.max(1)).filter_map(|i| all.get(i).copied()).collect()
+}
+
+/// A median-cut box: its weighted mean colour, pixel count and the pixel count of its heaviest bin.
+struct ColorBox {
+    mean: [f64; 3],
+    weight: f64,
+    peak: f64,
+}
+
+fn centers(boxes: &[ColorBox]) -> Vec<[f64; 3]> {
+    boxes.iter().map(|b| b.mean).collect()
+}
+
+/// Median cut to `k` colours, then weighted k-means refinement over histogram bins.
+fn kmeans_rgb(used: &[Used], k: usize) -> Vec<[f64; 3]> {
+    refine(used, centers(&median_cut(used, k, 0.0)))
+}
+
+/// Median cut: repeatedly split the box with the largest weighted extent, while there are fewer
+/// than `k` boxes and some box spans more than `spread` levels of a channel.
+fn median_cut(used: &[Used], k: usize, spread: f64) -> Vec<ColorBox> {
     if used.is_empty() {
-        return vec![[255.0; 3]];
+        return vec![ColorBox { mean: [255.0; 3], weight: 0.0, peak: 0.0 }];
     }
-    // Median cut: repeatedly split the box with the largest weighted extent.
     let mut boxes: Vec<Vec<usize>> = vec![(0..used.len()).collect()];
     while boxes.len() < k {
         let mut best: Option<(f64, usize, usize)> = None;
@@ -210,7 +304,7 @@ fn kmeans_rgb(used: &[(usize, [f64; 3], f64)], k: usize) -> Vec<[f64; 3]> {
                 wsum += used[i].2;
             }
             let (ch, range) = (0..3).map(|c| (c, hi[c] - lo[c])).fold((0, -1.0), |a, b| if b.1 > a.1 { b } else { a });
-            if range <= 0.0 {
+            if range <= spread.max(0.0) {
                 continue;
             }
             let score = range * wsum.sqrt();
@@ -235,21 +329,25 @@ fn kmeans_rgb(used: &[(usize, [f64; 3], f64)], k: usize) -> Vec<[f64; 3]> {
         boxes.push(b);
         boxes.push(tail);
     }
-    let mut centers: Vec<[f64; 3]> = boxes
+    boxes
         .iter()
         .map(|b| {
             let mut s = [0.0; 3];
-            let mut w = 0.0;
+            let (mut w, mut peak) = (0.0, 0.0f64);
             for &i in b {
                 for (acc, v) in s.iter_mut().zip(used[i].1) {
                     *acc += v * used[i].2;
                 }
                 w += used[i].2;
+                peak = peak.max(used[i].2);
             }
-            [s[0] / w, s[1] / w, s[2] / w]
+            ColorBox { mean: [s[0] / w, s[1] / w, s[2] / w], weight: w, peak }
         })
-        .collect();
-    // Lloyd refinement.
+        .collect()
+}
+
+/// Lloyd refinement of `centers` over the bins `used`.
+fn refine(used: &[Used], mut centers: Vec<[f64; 3]>) -> Vec<[f64; 3]> {
     for _ in 0..12 {
         let mut sum = vec![[0.0; 3]; centers.len()];
         let mut cnt = vec![0.0; centers.len()];

crates/trace/src/tests.rs

@@ -1,4 +1,5 @@
 use super::*;
+use vectorcraft_geom::Point;
 
 const BLACK: [u8; 4] = [0, 0, 0, 255];
 const WHITE: [u8; 4] = [255, 255, 255, 255];
@@ -348,3 +349,206 @@ fn an_image_too_large_to_trace_is_refused_before_decoding() {
     assert!(matches!(err, TraceError::TooLarge { width: 30_000, height: 30_000, .. }), "{err}");
     assert!(matches!(Raster::decode(&png_header(64, 64)), Err(TraceError::Decode(_))), "a small header goes on to decoding");
 }
+
+/// Four flat colours with anti-aliased (blended) edges between the quadrants.
+fn flat_quads() -> Raster {
+    const C: [[u8; 3]; 4] = [[220, 30, 30], [30, 200, 40], [30, 40, 210], [240, 220, 20]];
+    Raster::from_fn(100, 100, |x, y| {
+        let at = |x: u32, y: u32| C[usize::from(x >= 50) + 2 * usize::from(y >= 50)];
+        let (a, b) = (at(x, y), at(x.saturating_sub(1), y.saturating_sub(1)));
+        // Blend the pixels along the quadrant edges, as an anti-aliased picture has them.
+        let c: Vec<u8> = a.iter().zip(b).map(|(p, q)| ((u16::from(*p) + u16::from(q)) / 2) as u8).collect();
+        [c[0], c[1], c[2], 255]
+    })
+}
+
+/// A smooth two-dimensional colour gradient (continuous tone).
+fn gradient() -> Raster {
+    Raster::from_fn(128, 128, |x, y| [(x * 2) as u8, (y * 2) as u8, (255 - x - y / 2) as u8, 255])
+}
+
+fn palette(img: &Raster, palette: Palette, colors: u32, color_detail: f64) -> Vec<[u8; 3]> {
+    let p = TraceParams { mode: Mode::Color, palette, colors, color_detail, noise: 4, ..TraceParams::default() };
+    trace(img, &p).palette
+}
+
+#[test]
+fn palettes_parse_from_their_ids_and_names() {
+    for (id, want) in [
+        ("limited", Palette::Limited),
+        ("fullTone", Palette::FullTone),
+        ("Automatic", Palette::Automatic),
+        ("documentLibrary", Palette::DocumentLibrary),
+        ("library", Palette::DocumentLibrary),
+    ] {
+        let p: TraceParams = serde_json::from_value(serde_json::json!({ "palette": id })).unwrap();
+        assert_eq!(p.palette, want, "{id}");
+    }
+    assert_eq!(TraceParams::default().palette, Palette::Limited);
+    // The library's colours are looked up at every trace, not saved with the settings.
+    let v = serde_json::to_value(TraceParams { swatches: vec![[1, 2, 3]], ..TraceParams::default() }).unwrap();
+    assert!(v.get("swatches").is_none() && v["library"] == "document" && v["colorDetail"] == 50.0, "{v}");
+}
+
+#[test]
+fn full_tone_follows_the_tones_the_image_has() {
+    // Flat art keeps its few colours (and the tones of its blended edges); a gradient gets many,
+    // more with more detail.
+    let flat = palette(&flat_quads(), Palette::FullTone, 6, 50.0);
+    assert!((4..=10).contains(&flat.len()), "flat art: {flat:?}");
+    let few = palette(&gradient(), Palette::FullTone, 6, 10.0).len();
+    let many = palette(&gradient(), Palette::FullTone, 6, 90.0).len();
+    assert!(few > 6 && many > few && many <= FULL_TONE_MAX, "{few} then {many} colours");
+}
+
+#[test]
+fn automatic_traces_flat_art_with_its_colours_and_photos_in_full_tone() {
+    let flat = palette(&flat_quads(), Palette::Automatic, 2, 50.0);
+    assert_eq!(flat.len(), 4, "the four flat colours, whatever `colors` says: {flat:?}");
+    assert!(flat.iter().any(|c| c[0] > 200 && c[1] < 60 && c[2] < 60), "red is one of them: {flat:?}");
+    let tone = palette(&gradient(), Palette::Automatic, 2, 50.0);
+    assert_eq!(tone.len(), palette(&gradient(), Palette::FullTone, 2, 50.0).len(), "continuous tone: as Full Tone");
+}
+
+#[test]
+fn document_library_uses_the_most_used_swatches_exactly() {
+    let swatches = vec![[255, 0, 0], [0, 255, 0], [0, 0, 255], [255, 255, 0], [0, 0, 0], [255, 255, 255]];
+    let p = |colors| TraceParams {
+        mode: Mode::Color,
+        palette: Palette::DocumentLibrary,
+        colors,
+        swatches: swatches.clone(),
+        noise: 4,
+        ..TraceParams::default()
+    };
+    let hard = Raster::from_fn(100, 100, |x, y| match (x < 50, y < 50) {
+        (true, true) => [220, 30, 30, 255],
+        (false, true) => [30, 200, 40, 255],
+        (true, false) => [30, 40, 210, 255],
+        (false, false) => [240, 220, 20, 255],
+    });
+    let res = trace(&hard, &p(6));
+    let mut got = res.palette.clone();
+    got.sort_unstable();
+    assert_eq!(got, [[0, 0, 255], [0, 255, 0], [255, 0, 0], [255, 255, 0]], "the nearest swatch of each colour, as it is");
+    assert!(res.paths.iter().all(|t| swatches.contains(&t.color)));
+    // At most `colors` of them: the ones the most pixels are nearest to.
+    let two = trace(&hard, &p(2)).palette;
+    assert!(two.len() <= 2 && two.iter().all(|c| swatches.contains(c)), "{two:?}");
+    // Without library colours, it traces as Limited.
+    let none = TraceParams { swatches: vec![], ..p(4) };
+    assert_eq!(trace(&hard, &none).palette.len(), 4);
+}
+
+fn strokes(fills: bool) -> TraceParams {
+    TraceParams { strokes: true, fills, stroke_width: 6.0, noise: 4, ..bw() }
+}
+
+/// Endpoints (first and last anchor) of each open subpath of the stroked paths.
+fn stroked(res: &TraceResult) -> Vec<(&TracedPath, &vectorcraft_geom::SubPath)> {
+    res.paths.iter().filter(|p| p.stroke.is_some()).flat_map(|p| p.path.subpaths.iter().map(move |s| (p, s))).collect()
+}
+
+#[test]
+fn a_thin_line_traces_as_one_stroked_centre_line() {
+    // A 3 px wide diagonal line from (20, 20) to (180, 100).
+    let img = Raster::from_fn(200, 120, |x, y| {
+        let (px, py) = (x as f64 + 0.5, y as f64 + 0.5);
+        let t = (((px - 20.0) * 160.0 + (py - 20.0) * 80.0) / (160.0f64.powi(2) + 80.0f64.powi(2))).clamp(0.0, 1.0);
+        let (cx, cy) = (20.0 + 160.0 * t, 20.0 + 80.0 * t);
+        if (px - cx).hypot(py - cy) <= 1.5 { BLACK } else { WHITE }
+    });
+    let res = trace(&img, &strokes(true));
+    assert_eq!(res.paths.len(), 1, "{:?}", res.paths.iter().map(|p| p.stroke).collect::<Vec<_>>());
+    let p = &res.paths[0];
+    let width = p.stroke.expect("stroked");
+    assert!((2.0..=4.0).contains(&width), "width {width}");
+    assert_eq!(p.path.subpaths.len(), 1);
+    let sp = &p.path.subpaths[0];
+    assert!(!sp.closed);
+    let (a, b) = (sp.anchors[0].p, sp.anchors[sp.anchors.len() - 1].p);
+    let (a, b) = if a.x < b.x { (a, b) } else { (b, a) };
+    assert!(a.distance(Point::new(20.0, 20.0)) < 3.0 && b.distance(Point::new(180.0, 100.0)) < 3.0, "{a:?} … {b:?}");
+    // A straight line: a few anchors, all on it.
+    assert!(sp.anchors.len() <= 4, "{} anchors", sp.anchors.len());
+    // Without Create Strokes, the same line is a filled outline.
+    let filled = trace(&img, &bw());
+    assert!(filled.paths.iter().all(|p| p.stroke.is_none()) && filled.paths[0].path.subpaths[0].closed);
+}
+
+#[test]
+fn a_thin_ring_traces_as_a_closed_centre_line() {
+    let img = Raster::from_fn(120, 120, |x, y| {
+        let d = (x as f64 + 0.5 - 60.0).hypot(y as f64 + 0.5 - 60.0);
+        if (d - 40.0).abs() <= 1.5 { BLACK } else { WHITE }
+    });
+    let res = trace(&img, &strokes(true));
+    let lines = stroked(&res);
+    assert_eq!(lines.len(), 1, "one ring");
+    let sp = lines[0].1;
+    assert!(sp.closed);
+    let len = PathData::single(sp.clone()).length();
+    let want = std::f64::consts::TAU * 40.0;
+    assert!((len - want).abs() / want < 0.05, "length {len} vs {want}");
+}
+
+#[test]
+fn wide_areas_stay_filled_and_lines_cross_at_junctions() {
+    // A disc (r = 20) and, apart from it, a plus sign of 3 px wide bars.
+    let img = Raster::from_fn(200, 100, |x, y| {
+        let (px, py) = (x as f64 + 0.5, y as f64 + 0.5);
+        let disc = (px - 50.0).hypot(py - 50.0) <= 20.0;
+        let plus = ((px - 150.0).abs() <= 1.5 && (20.0..=80.0).contains(&py)) || ((py - 50.0).abs() <= 1.5 && (120.0..=180.0).contains(&px));
+        if disc || plus { BLACK } else { WHITE }
+    });
+    let res = trace(&img, &strokes(true));
+    let fills: Vec<_> = res.paths.iter().filter(|p| p.stroke.is_none()).collect();
+    assert_eq!(fills.len(), 1, "the disc");
+    let a = net_area(&fills[0].path);
+    assert!((a - std::f64::consts::PI * 400.0).abs() < 60.0, "disc area {a}");
+    let lines = stroked(&res);
+    assert!((2..=4).contains(&lines.len()), "{} centre lines", lines.len());
+    // The centre lines stop about half a width short of each end of the bars (their round caps
+    // cover it).
+    let total: f64 = lines.iter().map(|(_, s)| PathData::single((*s).clone()).length()).sum();
+    assert!((106.0..=120.0).contains(&total), "both bars' length: {total}");
+    let ends: Vec<Point> = lines.iter().flat_map(|(_, s)| [s.anchors[0].p, s.anchors[s.anchors.len() - 1].p]).collect();
+    for want in [Point::new(150.0, 20.0), Point::new(150.0, 80.0), Point::new(120.0, 50.0), Point::new(180.0, 50.0)] {
+        assert!(ends.iter().any(|e| e.distance(want) < 4.0), "a line ends near {want:?}: {ends:?}");
+    }
+    // Strokes only: the disc is outlined.
+    let res = trace(&img, &strokes(false));
+    assert!(res.paths.iter().all(|p| p.stroke.is_some()));
+    assert!(res.paths.iter().any(|p| p.stroke == Some(1.0) && p.path.subpaths[0].closed), "the disc's outline");
+}
+
+#[test]
+fn create_settings_parse_with_defaults() {
+    let p: TraceParams = serde_json::from_value(serde_json::json!({ "strokes": true, "strokeWidth": 4 })).unwrap();
+    assert!(p.fills && p.strokes && p.stroke_width == 4.0);
+    let d = TraceParams::default();
+    assert!(d.fills && !d.strokes && d.stroke_width == 10.0);
+}
+
+#[test]
+fn create_strokes_survives_noise_and_tiny_images() {
+    let mut seed = 0x9E37_79B9_7F4A_7C15u64;
+    let mut next = move || {
+        seed ^= seed << 13;
+        seed ^= seed >> 7;
+        seed ^= seed << 17;
+        seed
+    };
+    let noise: Vec<u8> = (0..120 * 120).flat_map(|_| if next() % 3 == 0 { BLACK } else { WHITE }).collect();
+    let noise = Raster::new(120, 120, noise);
+    for img in [noise, Raster::from_fn(1, 1, |_, _| BLACK), Raster::from_fn(3, 2, |x, _| if x == 1 { BLACK } else { WHITE })] {
+        for (fills, width) in [(true, 1.0), (false, 4.0), (true, 100.0)] {
+            for noise in [0, 1, 4] {
+                let p = TraceParams { strokes: true, fills, stroke_width: width, noise, ..TraceParams::default() };
+                for t in trace(&img, &p).paths {
+                    assert!(t.stroke.is_none_or(|w| w.is_finite() && w >= 1.0), "{:?}", t.stroke);
+                }
+            }
+        }
+    }
+}

crates/ui-egui/src/dock.rs

@@ -151,6 +151,7 @@ pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
     ui.ctx().data_mut(|d| {
         d.insert_temp(column_left_id(), column.left());
         d.insert_temp(floating::dock_rect_id(), dock);
+        d.insert_temp(floating::icons_rect_id(), column);
     });
 }
 

crates/ui-egui/src/floating.rs

@@ -70,6 +70,12 @@ pub(crate) fn dock_rect_id() -> Id {
 }
 
 /// The strip along the window's left edge where the Tools panel docks, as last laid out.
+/// The icon column's bounds (egui temp memory, one frame old), where panels without a tab in the
+/// tabbed group go back to when docked.
+pub(crate) fn icons_rect_id() -> Id {
+    Id::new("floating-icons-rect")
+}
+
 pub(crate) fn tools_zone_id() -> Id {
     Id::new("floating-tools-zone")
 }
@@ -216,7 +222,13 @@ fn drop_target(app: &VectorcraftApp, ctx: &egui::Context, what: Moving, at: Pos2
             return Some((Drop::Stack(first), head));
         }
     }
-    zone(dock_rect_id()).filter(|_| app.ui.dock && app.ui.screen_mode < 3).map(|r| (Drop::Dock, r))
+    let dock = zone(dock_rect_id()).filter(|_| app.ui.dock && app.ui.screen_mode < 3)?;
+    // Panels that aren't tabs of the tabbed group (or all of them, with it collapsed) go back to
+    // their icons: light up the icon column, where they land, rather than the tabs.
+    let tabbed = !app.ui.dock_collapsed
+        && own.and_then(|i| app.ui.floating_panels.get(i)).is_some_and(|g| ids_of(g).into_iter().any(|p| DockTab::from_id(p).is_some()));
+    let lit = if tabbed { dock } else { ctx.data(|d| d.get_temp::<Rect>(icons_rect_id())).unwrap_or(dock) };
+    Some((Drop::Dock, lit))
 }
 
 /// Light up a drop zone: over the docked panels, under the floating ones (the moved one too).
@@ -262,7 +274,13 @@ pub fn track(app: &mut VectorcraftApp, ctx: &egui::Context) {
     let ids = ids_of(g);
     let active = ids.get(g.active).copied().unwrap_or(id);
     match drop {
-        Drop::Dock => dock(&mut app.ui, &ids, active),
+        Drop::Dock => {
+            dock(&mut app.ui, &ids, active);
+            // One that went back to its icon pops out of it, so it doesn't seem to vanish.
+            if app.ui.dock_collapsed || DockTab::from_id(active).is_none() {
+                app.ui.open_panel = Some(active.to_string());
+            }
+        }
         Drop::Stack(onto) => stack(&mut app.ui, &ids, active, onto),
     }
 }
@@ -607,7 +625,7 @@ mod tests {
         h.hold(h.title("layers"), over);
         assert!(h.group("layers").contains(over), "the group follows the pointer");
         let target = drop_target(&h.app, &h.ctx, Moving::Panel("layers"), over);
-        assert_eq!(target.map(|t| t.0), Some(Drop::Dock), "the dock is the drop zone");
+        assert_eq!(target, Some((Drop::Dock, dock)), "the dock is the drop zone, lit whole: its tab comes back");
         h.release(over);
         assert!(h.groups().is_empty(), "docked: {:?}", h.groups());
         assert_eq!((h.dock_tabs().len(), h.app.ui.dock_tab), (3, DockTab::Layers), "back in the dock, shown");
@@ -666,6 +684,24 @@ mod tests {
         assert_eq!(h.icons().len(), count - 1, "Color is back in the column");
     }
 
+    #[test]
+    fn a_panel_dropped_on_the_dock_lights_up_and_pops_out_of_its_icon() {
+        let mut h = Harness::new();
+        let count = h.icons().len();
+        h.drag(h.icons()[0].center(), pos2(500.0, 400.0));
+        assert_eq!(h.groups(), [["color"]]);
+        // Over the tabbed group: Color has no tab there, so the icon column lights up, not the tabs.
+        let (dock, column) = (h.temp_rect(dock_rect_id()), h.temp_rect(icons_rect_id()));
+        let over = h.dock_tabs()[1].center();
+        h.hold(h.title("color"), over);
+        assert_eq!(drop_target(&h.app, &h.ctx, Moving::Panel("color"), over), Some((Drop::Dock, column)));
+        assert!(column.width() < dock.width(), "the column, not the whole dock: {column:?} {dock:?}");
+        // Dropped, it's back in the column and pops out of its icon rather than vanishing.
+        h.release(over);
+        assert!(h.groups().is_empty());
+        assert_eq!((h.icons().len(), h.app.ui.open_panel.as_deref()), (count, Some("color")));
+    }
+
     #[test]
     fn a_popped_out_panel_dragged_by_its_title_floats() {
         let mut h = Harness::new();

crates/ui-egui/src/i18n/es.tsv

@@ -1152,6 +1152,11 @@
 	Ignore	Ignorar
 	Ignore Artboards (all the art as one page)	Ignorar mesas de trabajo (toda la ilustración como una página)
 	Ignore White	Ignorar blanco
+	Palette:	Paleta:
+	Limited	Limitada
+	Full Tone	Tono completo
+	Document Library	Biblioteca del documento
+	Library:	Biblioteca:
 	Image	Imagen
 	Image Info	Información de imagen
 	Image Map:	Mapa de imagen:
@@ -1566,6 +1571,9 @@
 	No text selected	No hay texto seleccionado
 	No Thumbnails	Sin miniaturas
 	Noise	Ruido
+	Create:	Crear:
+	Fills	Rellenos
+	Strokes	Trazos
 	Nonbreaking Hyphen	Guion de no separación
 	Nonbreaking Space	Espacio de no separación
 	None	Ninguno

crates/ui-egui/src/i18n/fr.tsv

@@ -1151,6 +1151,11 @@
 	Ignore	Ignorer
 	Ignore Artboards (all the art as one page)	Ignorer les plans de travail (toute l’illustration sur une page)
 	Ignore White	Ignorer le blanc
+	Palette:	Palette :
+	Limited	Limitée
+	Full Tone	Tons continus
+	Document Library	Bibliothèque du document
+	Library:	Bibliothèque :
 	Image	Image
 	Image Info	Informations sur l’image
 	Image Map:	Image cliquable :
@@ -1563,6 +1568,9 @@
 	No text selected	Aucun texte sélectionné
 	No Thumbnails	Sans vignettes
 	Noise	Bruit
+	Create:	Créer :
+	Fills	Fonds
+	Strokes	Contours
 	Nonbreaking Hyphen	Trait d’union insécable
 	Nonbreaking Space	Espace insécable
 	None	Aucun

crates/ui-egui/src/i18n/it.tsv

@@ -1151,6 +1151,11 @@
 	Ignore	Ignora
 	Ignore Artboards (all the art as one page)	Ignora tavole da disegno (tutta la grafica come una sola pagina)
 	Ignore White	Ignora bianco
+	Palette:	Palette:
+	Limited	Limitata
+	Full Tone	Tono continuo
+	Document Library	Libreria del documento
+	Library:	Libreria:
 	Image	Immagine
 	Image Info	Informazioni immagine
 	Image Map:	Mappa immagine:
@@ -1566,6 +1571,9 @@
 	No text selected	Nessun testo selezionato
 	No Thumbnails	Nessuna miniatura
 	Noise	Disturbo
+	Create:	Crea:
+	Fills	Riempimenti
+	Strokes	Tracce
 	Nonbreaking Hyphen	Trattino indivisibile
 	Nonbreaking Space	Spazio indivisibile
 	None	Nessuno

crates/ui-egui/src/i18n/ja.tsv

@@ -1410,6 +1410,11 @@
 	Ignore	無視
 	Ignore Artboards (all the art as one page)	アートボードを無視 (すべてのアートを 1 ページとして扱う)
 	Ignore White	白を無視
+	Palette:	パレット:
+	Limited	限定
+	Full Tone	フルトーン
+	Document Library	ドキュメントライブラリ
+	Library:	ライブラリ:
 	Image Info	画像情報
 	Image Map:	イメージマップ:
 	Image Size	イメージサイズ
@@ -1696,6 +1701,9 @@
 	No symbols in this document	このドキュメントにシンボルはありません
 	No text selected	テキストが選択されていません
 	Noise	ノイズ
+	Create:	作成:
+	Fills	塗り
+	Strokes	線
 	None	なし
 	None.	なし。
 	Normal	通常

crates/ui-egui/src/i18n/ru.tsv

@@ -1149,6 +1149,11 @@
 	Ignore	Игнорировать
 	Ignore Artboards (all the art as one page)	Игнорировать монтажные области (весь рисунок как одна страница)
 	Ignore White	Игнорировать белый
+	Palette:	Палитра:
+	Limited	Ограниченная
+	Full Tone	Полутоновая
+	Document Library	Библиотека документа
+	Library:	Библиотека:
 	Image	Изображение
 	Image Info	Сведения об изображении
 	Image Map:	Карта изображения:
@@ -1562,6 +1567,9 @@
 	No text selected	Текст не выделен
 	No Thumbnails	Без миниатюр
 	Noise	Шум
+	Create:	Создать:
+	Fills	Заливки
+	Strokes	Обводки
 	Nonbreaking Hyphen	Неразрывный дефис
 	Nonbreaking Space	Неразрывный пробел
 	None	Нет

crates/ui-egui/src/i18n/zh-hans.tsv

@@ -1140,6 +1140,11 @@
 	Ignore	忽略
 	Ignore Artboards (all the art as one page)	忽略画板 (所有图稿作为一页)
 	Ignore White	忽略白色
+	Palette:	调板：
+	Limited	有限
+	Full Tone	全色调
+	Document Library	文档库
+	Library:	库：
 	Image	图像
 	Image Info	图像信息
 	Image Map:	图像映射：
@@ -1541,6 +1546,9 @@
 	No text selected	未选择文字
 	No Thumbnails	无缩略图
 	Noise	杂色
+	Create:	创建：
+	Fills	填色
+	Strokes	描边
 	Nonbreaking Hyphen	不断行连字号
 	Nonbreaking Space	不断行空格
 	None	无

crates/ui-egui/src/i18n/zh-hant.tsv

@@ -1169,6 +1169,11 @@
 	Ignore	略過
 	Ignore Artboards (all the art as one page)	忽略工作區域 (所有圖稿視為單一頁面)
 	Ignore White	忽略白色
+	Palette:	調色盤：
+	Limited	有限
+	Full Tone	全色調
+	Document Library	文件資料庫
+	Library:	資料庫：
 	Image	影像
 	Image Info	影像資訊
 	Image Map:	影像地圖：
@@ -1583,6 +1588,9 @@
 	No text selected	未選取文字
 	No Thumbnails	無縮圖
 	Noise	雜訊
+	Create:	建立：
+	Fills	填色
+	Strokes	筆畫
 	Nonbreaking Hyphen	不斷行連字號
 	Nonbreaking Space	不斷行空格
 	None	無

crates/ui-egui/src/panels/image_trace.rs

@@ -1,19 +1,51 @@
-//! Image Trace panel: preset, view, mode, threshold or colour count, and the Advanced section's
-//! fidelity options (open or closed as it was last left). With an Image Trace object selected,
-//! changing a setting re-traces it (one undo step per change; sliders apply when released) and
-//! changing the view redraws it without tracing again. With an image selected, Trace makes a new
-//! Image Trace object.
+//! Image Trace panel: preset, view, mode, palette (Color), threshold or colour count, and the
+//! Advanced section (open or closed as it was last left): fidelity, method, and Create: Fills /
+//! Strokes with the widest line stroked. With an Image Trace object selected, changing a setting
+//! re-traces it (one undo step per change; sliders apply when released) and changing the view
+//! redraws it without tracing again. With an image selected, Trace makes a new Image Trace object.
 
 use egui::Ui;
 use serde_json::{Value, json};
 use vectorcraft_doc::{Node, NodeKind, TraceView};
+use vectorcraft_engine::cmd::swatchlib::DOCUMENT_SWATCHES;
 
-use super::{first_selected, pstate, set_pstate};
+use super::{first_selected, library_panel, pstate, set_pstate, swatches};
 use crate::VectorcraftApp;
 use crate::widgets::{self, menu_item};
 
 const MODES: [(&str, &str); 3] = [("blackAndWhite", "Black and White"), ("grayscale", "Grayscale"), ("color", "Color")];
 
+/// Color mode's palettes (`palette` param ids), in panel order.
+const PALETTES: [&str; 4] = ["limited", "fullTone", "automatic", "documentLibrary"];
+
+/// Palette `id`, in the UI language.
+fn palette_label(id: &str) -> &'static str {
+    match id {
+        "fullTone" => tl!("Full Tone"),
+        "automatic" => tl!("Automatic"),
+        "documentLibrary" => tl!("Document Library"),
+        _ => tl!("Limited"),
+    }
+}
+
+/// The name of Document Library's library `key` (the document's swatches or a swatch library); a
+/// library that is gone shows its key.
+fn library_label(app: &VectorcraftApp, key: &str) -> String {
+    match swatches::limit_name(app, key) {
+        Some(_) if key == DOCUMENT_SWATCHES => tl!(swatches::DOCUMENT_SWATCHES).to_string(),
+        Some(name) => library_panel::library_name(key, &name).to_string(),
+        None => key.to_string(),
+    }
+}
+
+/// Document Library's choices: the document's swatches, then the colour libraries (`current`
+/// checked) → the key chosen.
+fn library_list(app: &VectorcraftApp, ui: &mut Ui, current: &str) -> Option<String> {
+    let document = menu_item(ui, swatches::DOCUMENT_SWATCHES, true, current == DOCUMENT_SWATCHES).then(|| DOCUMENT_SWATCHES.to_string());
+    ui.separator();
+    library_panel::library_items(ui, &swatches::colour_libraries(app), Some(current)).or(document)
+}
+
 /// Panel state: the preset name, the current parameters, the view and the last result's counts.
 #[derive(Clone, Default)]
 struct TraceUi {
@@ -213,16 +245,41 @@ pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
             retrace = true;
         }
     });
-    let bw = st.params["mode"].as_str() == Some("blackAndWhite");
-    let (key, label, range) = if bw {
-        ("threshold", tl!("Threshold"), 0.0..=255.0)
-    } else {
-        ("colors", if st.params["mode"] == "grayscale" { tl!("Grays") } else { tl!("Colors") }, 2.0..=256.0)
+    let mode = st.params["mode"].as_str().unwrap_or("blackAndWhite").to_string();
+    let palette = st.params["palette"].as_str().unwrap_or("limited").to_string();
+    if mode == "color" {
+        ui.horizontal(|ui| {
+            widgets::dim_label(ui, tl!("Palette:"));
+            let labels = PALETTES.map(palette_label);
+            if let Some(p) = widgets::dropdown_names(ui, "it-palette", palette_label(&palette), &labels, 170.0).and_then(|i| PALETTES.get(i)) {
+                st.params["palette"] = json!(p);
+                st.preset = "Custom".into();
+                retrace = true;
+            }
+        });
+        if palette == "documentLibrary" {
+            ui.horizontal(|ui| {
+                widgets::dim_label(ui, tl!("Library:"));
+                let key = st.params["library"].as_str().unwrap_or(DOCUMENT_SWATCHES).to_string();
+                if let Some(k) = widgets::combo(ui, "it-library", &library_label(app, &key), 170.0, false, |ui| library_list(app, ui, &key)) {
+                    st.params["library"] = json!(k);
+                    st.preset = "Custom".into();
+                    retrace = true;
+                }
+            });
+        }
+    }
+    // Full Tone and Automatic: how many colours (Less … More); else a count or the threshold.
+    let (key, label, range, suffix) = match mode.as_str() {
+        "blackAndWhite" => ("threshold", tl!("Threshold"), 0.0..=255.0, ""),
+        "grayscale" => ("colors", tl!("Grays"), 2.0..=256.0, ""),
+        _ if matches!(palette.as_str(), "fullTone" | "automatic") => ("colorDetail", tl!("Colors"), 0.0..=100.0, "%"),
+        _ => ("colors", tl!("Colors"), 2.0..=256.0, ""),
     };
     let mut v = st.params[key].as_f64().unwrap_or(0.0);
-    let (changed, release) = slider(ui, label, &mut v, range, "");
+    let (changed, release) = slider(ui, label, &mut v, range, suffix);
     if changed {
-        st.params[key] = json!(v.round() as u64);
+        st.params[key] = if key == "colorDetail" { json!(v.round()) } else { json!(v.round() as u64) };
         st.preset = "Custom".into();
     }
     retrace |= release;
@@ -254,6 +311,27 @@ pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
                 }
             }
         });
+        // Create: Fills and/or Strokes (one of them stays on), and the widest line stroked.
+        let create = |p: &Value, key: &str| p[key].as_bool().unwrap_or(key == "fills");
+        let strokes = create(&st.params, "strokes");
+        ui.horizontal(|ui| {
+            widgets::dim_label(ui, tl!("Create:"));
+            for (key, other, label) in [("fills", "strokes", tl!("Fills")), ("strokes", "fills", tl!("Strokes"))] {
+                let on = create(&st.params, key);
+                if widgets::check(ui, label, on, !on || create(&st.params, other)) {
+                    st.params[key] = json!(!on);
+                    st.preset = "Custom".into();
+                    retrace = true;
+                }
+            }
+        });
+        let mut v = st.params["strokeWidth"].as_f64().unwrap_or(10.0);
+        let (changed, release) = ui.add_enabled_ui(strokes, |ui| slider(ui, tl!("Stroke"), &mut v, 1.0..=100.0, " px")).inner;
+        if changed {
+            st.params["strokeWidth"] = json!(v.round());
+            st.preset = "Custom".into();
+        }
+        retrace |= release;
         for (key, label) in [("snapCurvesToLines", tl!("Snap Curves To Lines")), ("ignoreWhite", tl!("Ignore White"))] {
             let on = st.params[key].as_bool().unwrap_or(false);
             if widgets::check(ui, label, on, true) {
@@ -373,6 +451,52 @@ mod tests {
         assert!(frame(&mut app, &ctx, vec![]).iter().any(|(t, _)| t == "Outlines"));
     }
 
+    #[test]
+    fn the_palette_shows_in_color_mode_and_traces_again() {
+        let mut app = traced_app();
+        let ctx = egui::Context::default();
+        crate::theme::install_fonts(&ctx);
+        let has = |texts: &[(String, Rect)], s: &str| texts.iter().any(|(t, _)| t == s);
+        let palette = |app: &VectorcraftApp| target(app).2.map(|t| t["params"]["palette"].clone());
+        assert!(!has(&frame(&mut app, &ctx, vec![]), "Palette:"), "Black and White has no palette");
+        app.run("imageTrace.make", json!({"preset": "6 Colors"})).unwrap();
+        let texts = frame(&mut app, &ctx, vec![]);
+        assert!(has(&texts, "Palette:") && has(&texts, "Limited") && !has(&texts, "Library:"), "{texts:?}");
+        // Document Library traces again with the document's swatches, and names them.
+        click(&mut app, &ctx, "Limited");
+        click(&mut app, &ctx, "Document Library");
+        assert_eq!(palette(&app), Some(json!("documentLibrary")));
+        let texts = frame(&mut app, &ctx, vec![]);
+        assert!(has(&texts, "Library:") && has(&texts, "Document Swatches"), "{texts:?}");
+        // Full Tone's Colors is how many, Less (0%) … More (100%).
+        click(&mut app, &ctx, "Document Library");
+        click(&mut app, &ctx, "Full Tone");
+        assert_eq!(palette(&app), Some(json!("fullTone")));
+        let texts = frame(&mut app, &ctx, vec![]);
+        assert!(has(&texts, "50") && !has(&texts, "Library:"), "{texts:?}");
+    }
+
+    #[test]
+    fn create_strokes_traces_again_and_keeps_one_kind_on() {
+        let mut app = traced_app();
+        let ctx = egui::Context::default();
+        crate::theme::install_fonts(&ctx);
+        let create = |app: &VectorcraftApp| target(app).2.map(|t| (t["params"]["fills"].clone(), t["params"]["strokes"].clone()));
+        let texts = frame(&mut app, &ctx, vec![]);
+        for s in ["Create:", "Fills", "Strokes", "Stroke", "10"] {
+            assert!(texts.iter().any(|(t, _)| t == s), "{s}: {texts:?}");
+        }
+        // Fills alone can't be turned off.
+        click(&mut app, &ctx, "Fills");
+        assert_eq!(create(&app), Some((json!(true), json!(false))));
+        click(&mut app, &ctx, "Strokes");
+        assert_eq!(create(&app), Some((json!(true), json!(true))), "traced again with strokes");
+        click(&mut app, &ctx, "Fills");
+        assert_eq!(create(&app), Some((json!(false), json!(true))));
+        click(&mut app, &ctx, "Strokes");
+        assert_eq!(create(&app), Some((json!(false), json!(true))), "Strokes alone stays on");
+    }
+
     #[test]
     fn panel_and_menu_draw_headless() {
         let mut app = VectorcraftApp::new(vectorcraft_engine::Session::new(), Default::default());

docs/development.md

@@ -43,11 +43,12 @@ The canvas is rasterized on the CPU (`vectorcraft-render`, vello_cpu); the GPU (
   - **Automatic on Windows and macOS** is power saving: the system shows frames from any GPU, and presenting frames rendered on a discrete GPU through the integrated one made the window flicker on some hybrid laptops (#306).
   - **Automatic on Linux and the BSDs** keeps the system's order: Mesa's Vulkan device-select layer puts the GPU the desktop runs on first (the integrated one on hybrid laptops; `DRI_PRIME` and `MESA_VK_DEVICE_SELECT` steer it). A Wayland compositor may not accept frames from another GPU: on a desktop whose compositor ran on an NVIDIA GPU, rendering on the Ryzen's integrated GPU made KWin end the window's connection ("importing the supplied dmabufs failed") and 0.5.0 crashed at startup (#502).
   - 0.5.0 saved `powerSaving`, its default, for everyone; it reads as `automatic`.
-- **If the window fails on its adapter while starting up** (an error from wgpu, or a panic inside wgpu or egui-wgpu during the first frames), the app starts again without that adapter and tries the next one, telling which in the status bar; the run that failed keeps its log as `vectorcraft.1.log`. On Unix the new app replaces the process (an AppImage stays mounted); on Windows it starts beside it. The adapters left out travel in `VECTORCRAFT_GPU_SKIP` (`backend:vendor:device`, such as `Vulkan:1002:164e`), one more on each restart, so the restarts end. When no adapter is left, the app logs why and exits with an error instead of panicking.
+- **If the window fails on its adapter while starting up** (an error from wgpu, or a panic inside wgpu or egui-wgpu during the first frames), the app starts again without that adapter and tries the next one, telling which in the status bar; the run that failed keeps its log as `vectorcraft.1.log`. On Unix the new app replaces the process (an AppImage stays mounted); on Windows it starts beside it. Adapters are told apart by backend and PCI ids, or by name where the backend reports no ids (Metal lists every GPU of a dual-GPU Mac as `0000:0000`, #651). The adapters left out travel in `VECTORCRAFT_GPU_SKIP` (`backend:vendor:device`, such as `Vulkan:1002:164e`), one more on each restart, so the restarts end. When no adapter is left, the app logs why and exits with an error instead of panicking.
 - **Environment variables** for when the choice still goes wrong, all read at startup and stronger than the preference:
   - `WGPU_POWER_PREF`: `low`, `high` or `none` (the system's order).
   - `WGPU_ADAPTER_NAME`: part of an adapter's name, any case (`WGPU_ADAPTER_NAME=nvidia`, `=radv`, `=intel`); the names are in the log.
   - `WGPU_BACKEND`: the backends to use, such as `vulkan`, `dx12`, `metal` or `gl`.
+  - `WGPU_VALIDATION_INDIRECT_CALL=1`: turns wgpu's check of indirect draw arguments back on. VectorCraft draws nothing indirectly and turns it off, since the compute shader it needs fails to compile on some drivers (#651).
   - On Linux with Mesa, `MESA_VK_DEVICE_SELECT=10de:2f04!` (vendor:device as `vulkaninfo --summary` or `lspci -nn` show it) leaves only that GPU to Vulkan, and `DRI_PRIME=1` picks the other GPU.
 - Help › About and the control channel's `ui.inspect` (`graphicsAdapter`) show the adapter in use, and the app logs it at startup.