[PAMulligan]

Description

On Linux, electron-builder 26.8+ names the GUI binary after the package name, sanitized and lowercased, so @flavian/gui becomes @flaviangui. Its AppImage step then refuses the @ (validateCriticalPathString in appImageUtil.ts), so every Linux package build since v2.0.0 (electron-builder moved from 25.1.8 to 26.15.3 in #163) fails at "Package installer". macOS and Windows are unaffected: they fall back to productName.

This sets linux.executableName: flavian in packages/gui/electron-builder.yml, under linux: only, so Flavian.app and Flavian.exe keep their names (a top-level key would rename them too, which is what the Aurelius fix did).

A new packaging test, packages/gui/tests/packaging/electron-builder-config.test.mts, derives the Linux executable name the way electron-builder's LinuxPackager does and checks it against the AppImage name whitelist, and pins productName with no top-level executableName. It fails on main with "@flaviangui" and passes with the fix. js-yaml joins the GUI dev dependencies to read the config.

Related Issue

Closes #168

Type of Change

• Bug fix
• New feature
• Documentation update
• Chore
• Breaking change

Verification

Linux: a node:22-bookworm linux/amd64 container on a clean copy of main, running the gui-release.yml commands (electron-builder 26.15.3, Electron 42.11.16).

Step	Before	After
pnpm --filter @flavian/gui exec electron-builder --publish never	exit 1: executableName contains characters that cannot be safely used in file paths: @flaviangui	exit 0
packages/gui/dist/	linux-unpacked/@flaviangui, no AppImage	Flavian-2.1.0.AppImage, linux-unpacked/flavian
Launch under Xvfb	not reached	linux-unpacked/flavian boots and renders the setup view (Playwright, the same assertions as tests/smoke/smoke.mjs); the AppImage starts with --appimage-extract-and-run and stays up, with only D-Bus warnings from the bus-less container

macOS (this host, x64): electron-builder --dir --mac with the patched config still produces dist/mac/Flavian.app. Windows follows the same rule (productFilename falls back to productName when no top-level executableName is set) and is pinned by the test.

Checklist

• pnpm --filter @flavian/gui lint, typecheck and test (55 tests, 2 new)
• pnpm test:pipeline (133), pnpm test:claude (88), node scripts/claude-code-conformance.js (0 errors), bash scripts/check-doc-counts.sh
• pnpm lint:commits
• PHPCS and security scan: not applicable, no PHP changed
• Documentation: not needed, the comment in electron-builder.yml explains the setting
• gui-release.yml has still never run (release-please publishes with GITHUB_TOKEN, which starts no workflows). Fixing that trigger is out of scope here, as the issue says.

Local macOS runs of pnpm test:init (two Canva export tests) and the bats suites (eight convert-html-to-blocks tests) fail in scripts/canva-fse, which this diff does not touch; the same suites are green in CI on main.

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