Desktop drops shell environment when interactive probe times out

Description

Desktop probes the user shell with -il for up to five seconds. If that probe returns ETIMEDOUT, loadShellEnv returns null immediately instead of trying the existing -l fallback. The local sidecar then starts with the minimal GUI environment, so commands installed through Homebrew or user-local paths can intermittently fail with command not found.

This is a timeout edge case left after #26449.

Plugins

N/A - the failure occurs while Desktop initializes the sidecar environment.

OpenCode version

Desktop 1.18.29

Steps to reproduce

1. Launch Desktop from Finder with a minimal GUI PATH.
2. Use a login shell where interactive startup takes longer than five seconds, while login-only startup succeeds.
3. Observe [server] Interactive shell env probe timed out in main.log.
4. Run an agent shell command that needs a binary added by the login environment.
5. Observe command not found.

Expected: after the -il timeout, Desktop retries with -l before falling back to the app environment.

A deterministic source-level reproduction can mock spawnSync to return ETIMEDOUT: the current implementation returns null and calls only -il.

Screenshot and/or share link

N/A

Operating System

macOS 15.7.9

Terminal

OpenCode Desktop