Adds first-class core24 snap support through a new snapcraft config key, and restructures the snap target into per-core classes so each base gets its own code path.

The old snap key still works exactly as before — nothing breaks for existing users. The new snapcraft key gives you structured access to core18/20/22 (same behavior as before) and core24 (all-new).

New config shape

// electron-builder.json
{
  "snapcraft": {
    "base": "core24",
    "core24": {
      "useDestructiveMode": true,   // or useLXD / useMultipass / remoteBuild
      "extensions": ["gnome"],       // defaults to ["gnome"] unless destructive mode
      "stagePackages": ["default", "libdrm2"],
      "allowNativeWayland": true
    }
  }
}

For legacy bases:

{
  "snapcraft": {
    "base": "core22",
    "core22": {
      "confinement": "classic",
      "stagePackages": ["default", "libsecret-1-0"]
    }
  }
}

Pass-through mode for teams that manage their own snapcraft.yaml or via direct configuration (and verbatim usage by electron-builder):

{
  "snapcraft": {
    "base": "custom",
    "custom": { "yaml": "build/my-snapcraft.yaml" }
  }
}

core24 specifics

• Default build uses the gnome extension (handles content snaps, GTK theming, GPU). Explicitly set extensions: [] to opt out.
• gnome extension is incompatible with --destructive-mode. Setting useDestructiveMode: true while including gnome in extensions throws an InvalidConfigurationError with a clear message explaining why and what to do instead.
• Wayland is enabled by default for core24. Set allowNativeWayland: false to disable (sets DISABLE_WAYLAND=1).
• organize mappings are auto-generated at build time from the actual app directory, so helper binaries land under app/ inside the snap regardless of what Electron ships.
• Remote build support (Launchpad) for multi-arch without native hardware.

Implementation changes

The old monolithic snap.ts (396 lines) is gone. In its place:

LinuxTargetHelper.getSnapCore() reads snapcraft.base and returns the right implementation.

Tests

A new test-snap (core*) matrix job replaces the previous test-linux-native stub (which was if: false). It runs four parallel jobs, one per core:

• core18, core20, core22 — Docker image built on ghcr.io/canonical/snapcraft:7_core22 (Snapcraft 7 / Jammy)
• core24 — Docker image built on ghcr.io/canonical/snapcraft:8_core24 (Snapcraft 8 / Noble)

Both use --destructive-mode + SNAPCRAFT_BUILD_ENVIRONMENT=host so no LXD or Multipass daemon is required in CI.

The snapHeavyTest.ts suite also has install+launch tests (extract with unsquashfs, assert snap structure, run binary with --version) that run on native Linux CI runners with squashfs-tools available, skipped inside Docker.

The existing snapTest.ts unit tests still run and cover all the descriptor-level assertions (plugs, slots, extensions, compression, etc.) through snapshot testing.

Breaking changes

None for snap users. The snapcraft key is additive.