Shipping Gnomad Webcanvas on Linux

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Shipping Gnomad Webcanvas on Linux — Beta 6

June 23, 2026 · Gnomad Webcanvas · v0.1.0-beta.6

Today we took Gnomad Webcanvas from “works on my MacBook” to actually usable on Linux — specifically Fedora/Nobara with Wayland, WebKitGTK, and real desktop installs. This post is the story of what broke, what we fixed, and what shipped.

What is Webcanvas?

Gnomad Webcanvas is a live HTML/CSS/JS playground: three Monaco editor panes, instant iframe preview, export to ZIP, and native Open/Save when you run the Tauri desktop shell. Same React codebase in the browser or on the desktop.

If you just want to try it:

The mission for today

We had four goals:

  1. Build and install on Linux (RPM on Nobara/Fedora 43)
  2. Harden the menu bar — Close, Help, Check for Updates, platform-correct menus
  3. Split macOS and Linux code paths so each OS gets idiomatic behavior without #ifdef soup in one file
  4. Fix everything that broke when we turned on real desktop security (CSP) and quit handling

We hit all four. Beta 6 is tagged and CI is publishing installers.

Linux build: from crash to RPM

Getting a Tauri + WebKitGTK app running on modern Fedora is… character-building.

Wayland + WebKit

On Wayland (KDE Plasma), WebKitGTK can show a blank window or crash unless you force the X11 backend:

GDK_BACKEND=x11 WEBKIT_DISABLE_DMABUF_RENDERER=1 gnomad-webcanvas

We baked those flags into the desktop launcher and added scripts/launch-linux.sh for a one-command start.

AppImage on Fedora 43

linuxdeploy ships an old strip binary that chokes on modern ELF .relr.dyn sections. Fix:

export NO_STRIP=1
export APPIMAGE_EXTRACT_AND_RUN=1
npm run tauri:build:linux

That script is now the canonical Linux release path (scripts/build-linux-release.sh).

One build, not one per kernel

A common question: do we need a separate installer for every Linux kernel?

No. Ship x86_64 builds in three package formats:

Format Best for
.rpm Fedora, Nobara, RHEL
.deb Ubuntu, Debian
AppImage Portable / unknown distro

Kernel updates on the same machine do not require a new download. You only need separate builds per CPU architecture (e.g. ARM64 later).

Bug 1: Editors stuck on “Loading editor…”

Symptom: HTML, CSS, and JS panes showed “Loading editor…” forever. Preview worked fine.

Cause: We added a Content Security Policy for desktop security. Monaco’s default loader pulls from cdn.jsdelivr.net. CSP blocked it. loader.init() failed silently.

Fix: Bundle Monaco from node_modules with Vite worker imports (src/lib/monacoSetup.ts). Editors load offline, no CDN, CSP-compliant. The Monaco chunk is ~4 MB — acceptable for a desktop code editor.

Bug 2: Quit and Close did nothing

Symptom: File → Quit, the window X button, and Ctrl+W appeared to do nothing. Old instances lingered after reinstall.

Cause: Rust called prevent_close() on every close request (for unsaved-changes prompts), but the frontend called destroy() which does not clear that guard. The app could never finish exiting.

Fix:

You can now quit cleanly. If something ever gets stuck: pkill gnomad-webcanvas.

Bug 3: “Could not connect to localhost: Connection refused”

Symptom: After reinstall, the app showed a connection error to localhost.

Cause: An old AppImage extract from June was still running from ~/.local/opt/gnomad-webcanvas/. It pointed at the dev server (http://localhost:5173). Single-instance mode kept focusing that zombie instead of the new RPM.

Fix: Kill stale processes, remove the old extract, launch /usr/bin/gnomad-webcanvas explicitly. The launch script handles this automatically.

Platform split: one repo, two personalities

macOS and Linux expect different menu bar layouts:

Platform Menu structure
macOS App menu · File · Edit · Window (Close Window lives here per HIG)
Linux File · Edit · Window · Help (About + Check for Updates)

We split:

Documented in PLATFORM_SPLIT.md.

Security and quality pass

Alongside the bug fixes:

What shipped in v0.1.0-beta.6

Download: Releases — v0.1.0-beta.6

What’s next

If you’re on Fedora/Nobara, install the RPM, run with the X11 env vars if needed, and tell us what breaks. Beta means we’re listening.

Built with ❤️ by Gnomad Studio 🦙