feat(native): enable the GPU test renderer and captureScreenshot on Linux via the test-support feature

.github/workflows/ci.yml

@@ -32,11 +32,13 @@ jobs:
             bunTarget: bun-darwin-arm64
             build: bun run build
           # ── Linux (Vulkan/wgpu) ────────────────────────────────────
-          # build:release disables test-support until wgpu image readback lands.
+          # test-support (TestGpuixRenderer + render_to_image) is on by
+          # default; the wgpu offscreen image readback it relies on has
+          # landed, so Linux ships the same test renderer as macOS/Windows.
           - host: ubuntu-latest
             target: x86_64-unknown-linux-gnu
             bunTarget: bun-linux-x64
-            build: bun run build:release
+            build: bun run build
           # ── Windows (Direct3D) ─────────────────────────────────────
           # Test support includes TestGpuixRenderer and render_to_image.
           - host: windows-latest
@@ -333,6 +335,74 @@ jobs:
         run: bun run test
         working-directory: examples
 
+  test-linux:
+    name: test-linux
+    needs: build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      # wgpu (Vulkan) needs an ICD on a headless runner; the test renderer
+      # renders offscreen through the same wgpu path as production.
+      - name: Install Linux dependencies
+        run: |
+          sudo apt-get update && sudo apt-get install -y \
+            libvulkan1 \
+            vulkan-validationlayers \
+            libfontconfig1 \
+            libwayland-client0 \
+            libx11-6
+
+      - name: Setup bun
+        uses: oven-sh/setup-bun@v2
+
+      - name: Setup node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 24
+
+      - name: Install dependencies
+        run: bun install
+
+      - name: Download Linux artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: bindings-x86_64-unknown-linux-gnu
+          path: packages/native/
+
+      - name: Load native binding with Bun
+        run: bun -e "import('./packages/native/index.js').then(() => console.log('Linux native binding OK (bun)'))"
+
+      - name: Load native binding with Node
+        run: node -e "import('./packages/native/index.js').then(() => console.log('Linux native binding OK (node)'))"
+
+      - name: Verify Linux test renderer
+        run: bun -e "import { statSync } from 'node:fs'; const { TestGpuixRenderer } = await import('./packages/native/index.js'); const renderer = new TestGpuixRenderer(320, 200); renderer.applyBatch(JSON.stringify([['createElement',1,'text'],['setText',1,'Linux test renderer'],['setRoot',1]])); renderer.flush(); renderer.captureScreenshot('linux-test-renderer.png'); if (renderer.getAllText()[0] !== 'Linux test renderer' || statSync('linux-test-renderer.png').size === 0) throw new Error('TestGpuixRenderer did not render')"
+
+      - name: Build native shared TypeScript
+        run: bun run build:js
+        working-directory: packages/native
+
+      - name: Run React tests
+        run: bun run test
+        working-directory: packages/react
+
+      - name: Build React package
+        run: bun run build
+        working-directory: packages/react
+
+      - name: Run Solid tests
+        run: bun run test
+        working-directory: packages/solid
+
+      - name: Build Solid package
+        run: bun run build
+        working-directory: packages/solid
+
+      - name: Run example tests
+        run: bun run test
+        working-directory: examples
+
   publish-cli:
     name: publish-cli
     if: github.event_name == 'push' && github.ref == 'refs/heads/main'
@@ -376,6 +446,7 @@ jobs:
       - build
       - test
       - test-windows
+      - test-linux
     permissions:
       contents: write
       id-token: write

.gitmodules

@@ -1,4 +1,4 @@
 [submodule "zed"]
 	path = zed
-	url = https://github.com/remorses/zed.git
-	branch = gpuix
+	url = https://github.com/knoopx/zed.git
+	branch = main

packages/native/index.d.ts

@@ -399,7 +399,7 @@ export declare class TestGpuixRenderer {
   getScrollOffset(elementId: number): Array<number> | null
   /**
    * Capture a screenshot of the current rendered state and save as PNG.
-   * Supported on macOS through Metal and Windows through DirectX.
+   * Supported on macOS through Metal, Windows through DirectX, and Linux through a wgpu offscreen readback.
    */
   captureScreenshot(path: string): void
   /**

packages/native/src/lib.rs

@@ -2,10 +2,7 @@
 
 #[cfg(all(
     not(all(target_arch = "wasm32", target_os = "unknown")),
-    not(all(
-        feature = "test-support",
-        any(target_os = "macos", target_os = "windows")
-    ))
+    not(feature = "test-support")
 ))]
 use napi::bindgen_prelude::*;
 #[cfg(not(all(target_arch = "wasm32", target_os = "unknown")))]
@@ -35,7 +32,7 @@ mod updater;
 
 #[cfg(all(
     feature = "test-support",
-    any(target_os = "macos", target_os = "windows")
+    not(all(target_arch = "wasm32", target_os = "unknown"))
 ))]
 mod test_renderer;
 
@@ -45,15 +42,16 @@ pub use style::*;
 
 #[cfg(any(
     test,
-    not(all(
-        feature = "test-support",
-        any(target_os = "macos", target_os = "windows")
-    ))
+    all(
+        not(all(target_arch = "wasm32", target_os = "unknown")),
+        not(feature = "test-support")
+    )
 ))]
 const TEST_GPUIX_RENDERER_UNAVAILABLE: &str = concat!(
-    "TestGpuixRenderer is macOS and Windows only. ",
-    "Linux builds have no test-support because wgpu cannot read a rendered image back yet. ",
-    "GpuixRenderer still works on Linux."
+    "TestGpuixRenderer requires the `test-support` feature. ",
+    "Rebuild the native package with the `test-support` feature (a default feature) ",
+    "to get the real GPU test renderer. ",
+    "GpuixRenderer works on all desktop platforms including Linux."
 );
 
 /// True only when this binary compiled the real GPU test renderer.
@@ -62,26 +60,20 @@ const TEST_GPUIX_RENDERER_UNAVAILABLE: &str = concat!(
 pub fn has_test_gpuix_renderer() -> bool {
     cfg!(all(
         feature = "test-support",
-        any(target_os = "macos", target_os = "windows")
+        not(all(target_arch = "wasm32", target_os = "unknown"))
     ))
 }
 
 #[cfg(all(
     not(all(target_arch = "wasm32", target_os = "unknown")),
-    not(all(
-        feature = "test-support",
-        any(target_os = "macos", target_os = "windows")
-    ))
+    not(feature = "test-support")
 ))]
 #[napi]
 pub struct TestGpuixRenderer;
 
 #[cfg(all(
     not(all(target_arch = "wasm32", target_os = "unknown")),
-    not(all(
-        feature = "test-support",
-        any(target_os = "macos", target_os = "windows")
-    ))
+    not(feature = "test-support")
 ))]
 #[napi]
 impl TestGpuixRenderer {
@@ -96,12 +88,16 @@ mod tests {
     use super::*;
 
     #[test]
-    fn unavailable_message_explains_linux() {
-        assert!(TEST_GPUIX_RENDERER_UNAVAILABLE.contains("macOS and Windows only"));
+    fn unavailable_message_explains_test_support() {
+        assert!(TEST_GPUIX_RENDERER_UNAVAILABLE.contains(
+            "requires the `test-support` feature"
+        ));
+        assert!(TEST_GPUIX_RENDERER_UNAVAILABLE.contains(
+            "Rebuild the native package with the `test-support` feature"
+        ));
         assert!(TEST_GPUIX_RENDERER_UNAVAILABLE.contains(
-            "Linux builds have no test-support because wgpu cannot read a rendered image back yet"
+            "GpuixRenderer works on all desktop platforms including Linux"
         ));
-        assert!(TEST_GPUIX_RENDERER_UNAVAILABLE.contains("GpuixRenderer still works on Linux"));
     }
 
     #[cfg(not(all(target_arch = "wasm32", target_os = "unknown")))]
@@ -111,17 +107,14 @@ mod tests {
             has_test_gpuix_renderer(),
             cfg!(all(
                 feature = "test-support",
-                any(target_os = "macos", target_os = "windows")
+                not(all(target_arch = "wasm32", target_os = "unknown"))
             ))
         );
     }
 
     #[cfg(all(
         not(all(target_arch = "wasm32", target_os = "unknown")),
-        not(all(
-            feature = "test-support",
-            any(target_os = "macos", target_os = "windows")
-        ))
+        not(feature = "test-support")
     ))]
     #[test]
     fn stub_constructor_explains_why() {

packages/native/src/renderer.rs

@@ -489,7 +489,7 @@ enum UiCommand {
         input: KeyInput,
         response: SyncSender<std::result::Result<(), String>>,
     },
-    #[cfg(all(target_os = "windows", feature = "test-support"))]
+    #[cfg(all(any(target_os = "windows", target_os = "linux"), feature = "test-support"))]
     CaptureScreenshot {
         path: String,
         response: SyncSender<std::result::Result<(), String>>,
@@ -857,7 +857,7 @@ async fn run_ui_commands(
                     .ok();
                 result
             }
-            #[cfg(all(target_os = "windows", feature = "test-support"))]
+            #[cfg(all(any(target_os = "windows", target_os = "linux"), feature = "test-support"))]
             UiCommand::CaptureScreenshot { path, response } => {
                 let error_response = response.clone();
                 let result = window.update(cx, move |_view, window, cx| {
@@ -2753,14 +2753,21 @@ impl GpuixRenderer {
             return recv_ui_response(receiver, "screenshot capture")?.map_err(Error::from_reason);
         }
 
+        #[cfg(all(target_os = "linux", feature = "test-support"))]
+        {
+            let (response, receiver) = sync_channel(1);
+            self.send_ui_command(UiCommand::CaptureScreenshot { path, response })?;
+            return recv_ui_response(receiver, "screenshot capture")?.map_err(Error::from_reason);
+        }
+
         #[cfg(not(all(
             feature = "test-support",
-            any(target_os = "macos", target_os = "windows")
+            any(target_os = "macos", target_os = "windows", target_os = "linux")
         )))]
         {
             let _ = path;
             Err(Error::from_reason(
-                "captureScreenshot needs a test-support build on macOS or Windows",
+                "captureScreenshot needs a test-support build on macOS, Windows, or Linux",
             ))
         }
     }

packages/native/src/test_renderer.rs

@@ -1,7 +1,8 @@
 /// TestGpuixRenderer — GPU-backed GPUI test renderer exposed to Node.js via napi.
 ///
-/// Uses gpui::VisualTestAppContext with the native Metal or DirectX renderer
-/// and TestDispatcher for deterministic scheduling. Runs the SAME GpuixView,
+/// Uses gpui::VisualTestAppContext with the native GPU renderer (Metal on
+/// macOS, DirectX on Windows, Vulkan on Linux) and TestDispatcher for
+/// deterministic scheduling. Runs the SAME GpuixView,
 /// build_element(), apply_styles(), and event handlers as production.
 ///
 /// Windows are positioned offscreen at (-10000, -10000) — invisible but
@@ -190,8 +191,9 @@ fn install_test_image_http_client(cx: &mut gpui::App) {
 // ── TestGpuixRenderer ────────────────────────────────────────────────
 
 /// GPU-backed GPUI test renderer. Uses VisualTestAppContext with the native
-/// Metal or DirectX renderer and TestDispatcher for deterministic scheduling.
-/// Same GpuixView and rendering pipeline as production.
+/// GPU renderer (Metal on macOS, DirectX on Windows, Vulkan on Linux) and
+/// TestDispatcher for deterministic scheduling. Same GpuixView and rendering
+/// pipeline as production.
 ///
 /// Usage from JS:
 ///   const r = new TestGpuixRenderer()
@@ -1021,7 +1023,7 @@ impl TestGpuixRenderer {
     }
 
     /// Capture a screenshot of the current rendered state and save as PNG.
-    /// Supported on macOS through Metal and Windows through DirectX.
+    /// Supported on macOS through Metal, Windows through DirectX, and Linux through a wgpu offscreen readback.
     #[napi]
     pub fn capture_screenshot(&self, path: String) -> Result<()> {
         with_test_state(|cx, window, view| {