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
 

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
     };

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.