NoSignal-OS/os updates/xdg-terminal-exec-handler

xdg-terminal-exec-handler

Symptom

A critical desktop notification at/after login:

app2unit: Error — Executable not found: 'xdg-terminal-exec'

Launching any Terminal=true .desktop entry through app2unit — or app2unit -T — silently fails. app2unit is the launcher behind many NoSignal binds (terminal, browser, editor, file explorer, pavucontrol…) and the Caelestia launcher's app-open path, so this is user-visible.

Cause

app2unit hardcodes its terminal handler:

A2U__TERMINAL_HANDLER=xdg-terminal-exec

…but NoSignal never shipped xdg-terminal-exec (not in PATH, not a package), and there is no ~/.config/xdg-terminals.list. Reproduce:

$ app2unit -T -- true
Terminal launch requested but 'xdg-terminal-exec' is unavailable!

Default terminal on this build is kitty.

Fix

Two layers:

1. Preferred (builder): add the freedesktop xdg-terminal-exec package to the ISO package set and ship a system xdg-terminals.list (/etc/xdg/xdg-terminals.list = kitty.desktop). That makes app2unit's default handler resolve properly for everyone.
2. Offline fallback (this component): install-xdg-terminal-exec-handler.sh drops a tiny xdg-terminal-exec shim into ~/.local/bin that execs the configured terminal ($TERMINAL, else kitty) per the xdg-terminal-exec calling convention, and seeds ~/.config/xdg-terminals.list. The installer is idempotent and self-correcting: if the real package later lands in a system bin, it removes the shim so it no longer shadows it.

Files

• xdg-terminal-exec — the shim.
• install-xdg-terminal-exec-handler.sh — idempotent installer.
• migrations/1781427600-xdg-terminal-exec-handler.sh — delegates to it.

Verify

app2unit -T -- true        # exits 0, no "unavailable" error

Notes / limitation

The shim passes args straight through to the terminal; it does not parse xdg-terminal-exec-specific options (--app-id= etc.). For full fidelity ship the real package — the shim is the offline stop-gap. No secrets, no per-user identity; honours $TERMINAL.