fix(desktop): resolve WSL OpenCode from PATH - #44514

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Potential Duplicate Found

PR #44512: fix(desktop): use PATH for WSL probe

• fix(desktop): use PATH for WSL probe #44512

This appears to be a closely related PR addressing the same issue. Both PRs aim to resolve OpenCode from PATH in WSL environments. PR #44512 is focused on WSL probe detection using PATH, while PR #44514 (current) resolves the WSL OpenCode executable from PATH with a fallback. These are likely addressing related or overlapping aspects of the same issue (#38309).

AI code review — automated review for reference, author can ignore or act on any point.

Overall: right fix direction — the old probe only accepted the fixed install path, so distro-managed installs were invisible, and stripping Windows interop entries before command -v correctly avoids resolving a Windows shim. A few notes:

1. packages/desktop/src/main/wsl/runtime.ts:315 — the filter relies on awk -v RS=: treating RS as a regex (multi-character). That works on gawk and modern mawk, but busybox awk (Alpine, minimal images used as WSL distros) has historically been inconsistent here, and this runs before any opencode binary exists to guarantee anything about the environment. A pure-sh filter sidesteps the dialect question entirely, e.g. building the filtered PATH with case in an IFS=: loop, or tr ':' '\n' | grep -v ... | paste -sd :.

2. Same line — /mnt/ hardcodes the default WSL automount root. Users who set a custom automountRoot (or disable appendWindowsPath but keep tools under another mountpoint) will either still get interop pollution (custom root ≠ /mnt) or lose legitimate distro-side entries installed under a /mnt path. Matching the interop entries more precisely (e.g. drive-letter roots like /mnt/?/:) or reading the automount setting would make this robust; worth at least a comment documenting the assumption.

3. Minor: with both installs present, the PATH binary now silently wins over the managed ~/.opencode/bin/opencode — if the desktop app assumes its own managed version, logging which path was resolved (once, at probe time) will save future debugging.

Tests pin the exact argv and both resolution outcomes — good, though asserting on a substring (command -v opencode) instead of the full command string would make intentional edits less churn-y.

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