[Bug]: Linux AppImage 0.0.41-nightly.20260914.1687 returns HTTP 500 — static handler uses fs.open on app.asar

Summary

The Linux AppImage starts, but the backend returns HTTP 500 for GET /. The desktop UI cannot load.

Version

• T3 Code: 0.0.41-nightly.20260914.1687
• Package: Linux x86_64 AppImage, 188708343 bytes
• Electron 44.1.0, Node 24.19.0, Chrome 152.0.7977.65
• Ubuntu 26.04.1 LTS, GNOME on Wayland

Steps to reproduce

1. Run T3-Code-0.0.41-nightly.20260914.1687-x86_64.AppImage.
2. Wait for backend ready in ~/.local/state/t3code/t3code.log.
3. Run curl -i http://127.0.0.1:3773/.

Actual result

HTTP/1.1 500 Internal Server Error
content-type: text/plain
content-length: 21

Internal Server Error

Expected result

The backend returns the web client. The desktop UI loads.

Cause

The static handler calls FileSystem.open on this path:

/tmp/.mount_T3-Cod.../resources/app.asar/apps/server/dist/client/index.html

The Electron asar layer fails the open call with ENOENT:

openStaticFile -> PlatformError: NotFound: FileSystem.open (.../app.asar/apps/server/dist/client/index.html)
ENOENT, apps/server/dist/client/index.html not found in .../app.asar

The file is present in the archive. fs.statSync returns size 20143, and fs.readFileSync returns valid HTML. fs.openSync and fs.promises.open fail with ENOENT. Electron asar support implements stat and readFile, but not open.

Regression

PR #9669 added the file-handle streaming path. That code returns 500 on PlatformError. The failure occurs when the client files are inside app.asar, as in the AppImage build.

This is not #11523. #11523 reports truncated assets on the t3code:// path.

Suggested fix

Read the file with FileSystem.readFile, or mark the client directory as unpacked in the AppImage build.

Workaround

Run an older AppImage.

Start with the openStaticFile entry point and the FileSystem.open call, then compare the streaming path introduced by PR #9669 with FileSystem.readFile. Reproduce using the AppImage and curl against http://127.0.0.1:3773/; done means the request returns the web client instead of HTTP 500 and the desktop UI loads.