[only21mil]

Re-lands #19589, which was merged and then reverted in #22222 with the other desktop fixes from the takeover batch. The revert comment on #19589 asked for a fresh PR from the original commit, run on a real build that already has user state. This branch is git cherry-pick -x of the #19589 squash commit (115e405) onto current main. It applied cleanly with no edits.

Problem

Every packaged Linux launch copies prod-resources/icon.png out of app.asar with copyFile. Electron serves that copy by extracting the ASAR entry to a temporary file, and it never deletes it. Each launch leaves one .org.chromium.Chromium.* file the size of the icon (549,578 bytes) in $TMPDIR. That includes launches the single-instance lock rejects, which is the case reported in #17737.

Change

Both icon installers (DesktopPreReadyPlatform.ts before ready, DesktopLinuxUrlHandler.ts after ready) now read the bundled icon bytes, compare them with the installed icon, and write it with writeFile only when it is missing or different. Reading a file from the ASAR doesn't extract it. Icon errors still don't block desktop registration. The code is the #19589 commit as merged, unchanged.

Scope and approval

• Bug: [Bug]: Each second-instance launch on Linux leaves a copy of the app icon in /tmp #17737. The maintainer reopened it after confirming this launch path: [Bug]: Each second-instance launch on Linux leaves a copy of the app icon in /tmp #17737 (comment)
• fix(desktop): avoid temporary icon copies on Linux launches #19589 was merged and then reverted in revert: fourteen unverified desktop fixes from the takeover campaign #22222. The revert comment says how to bring it back: fix(desktop): avoid temporary icon copies on Linux launches #19589 (comment)
• Linux only. Both code paths run only when the platform is linux and the app is packaged.
• As fix(desktop): avoid temporary icon copies on Linux launches #19589 said, this fixes the per-launch copies. It doesn't claim to fix the idle-time growth also described in [Bug]: Each second-instance launch on Linux leaves a copy of the app icon in /tmp #17737.

Verification

Real build with existing user state, Linux x64 (Fedora 44):

1. Built unsigned AppImages for main (774c6c1) and for this branch with node scripts/build-desktop-artifact.ts --platform linux --target AppImage --arch x64. The main bundle's main.cjs has the copyFileSync of prod-resources/icon.png; the branch bundle doesn't.
2. Ran each one under Xvfb with env -i, a throwaway HOME and its own TMPDIR, so every app path (~/.t3, ~/.config, ~/.local/share) was isolated.
3. Launches 1-3 used the main AppImage. Launch 1 went through first-run setup. Launch 2 added a local git project (demo-app), created a thread by sending a message, and changed two settings (Working section on, Hide whitespace changes off). A stub claude CLI that only answers --version made a provider selectable, so the thread's turn fails by design.
4. Launches 4-7 used the branch AppImage on that same profile. Before launch 6, I replaced the installed icon with 17 stale bytes.
5. Then, one at a time on the same profile, each build ran as a primary instance plus two second-instance launches.

Each main exit left one more icon-sized temp file:

The branch left none, and launch 6 restored the stale icon to the bundled bytes:

Second-instance launches, the #17737 case. Exit code 130 is how the app exits when the single-instance lock refuses a launch, on both builds:

In launches 3 through 6, the project, the thread with its message and both settings read back unchanged from the UI and from ~/.t3/userdata. Launch 7 rechecked the settings. None of the 9 app logs has an icon warning.

Main, launch 3:

Branch, launch 5, same profile:

The setting as changed on main in launch 2, then still set on the branch in launch 7:

Focused tests: 6 of 23 fail with main's production code, and all 23 pass on the branch. The screenshots below predate main's test purge (#22557), when the same two files held 32 tests and 7 failed.

Also run on the branch: tsc-rs --noEmit in apps/desktop (a planted type error fails it), plus vp fmt --check and vp lint --report-unused-disable-directives on the four changed files.

Not checked:

• Other distros, a real GNOME or KDE Wayland session (only Xvfb with no window manager ran), and arm64.
• The .deb target. It was built but not installed or run.
• A real provider. The stub CLI's turn fails on purpose.
• macOS and Windows. Neither runs these code paths.
• The idle-time file growth from [Bug]: Each second-instance launch on Linux leaves a copy of the app icon in /tmp #17737.

The production fix is the #19589 squash commit, unchanged. So are its tests, except where merging main's test purge (#22557) trimmed DesktopPreReadyPlatform.test.ts: the pre-ready icon-read fallback test checks the written files, the other two icon tests check the installed icon bytes instead of asserting mock calls, and the repeated-launch test also checks that the icon is written once. They were written with Claude Opus 5.5 and revised in the maintainer takeover, with GPT-6.1 Sol on the implementation and GPT-6 Astra on the tests. Re-land, packaged-build verification, PR description and images by Claude Opus 5.5 in T3 Code Nightly.

🤖 Generated with Claude Opus 5.5 in T3 Code Nightly