Resolve Microsoft Store pwsh aliases
解析 Microsoft Store 的 pwsh 别名
`resolvePwshPath` documented that Microsoft Store installs resolve through PATH, but its existence probe was `existsSync`, which stats a candidate and therefore follows reparse points. The Store's `%LOCALAPPDATA%\Microsoft\WindowsApps\pwsh.exe` is an app execution alias whose target directory ACL refuses stat (EACCES), so `existsSync` missed it and resolution silently fell through to Windows PowerShell 5.1 on hosts w
English
Problem
resolvePwshPath documented that Microsoft Store installs resolve through PATH, but its existence probe was existsSync, which stats a candidate and therefore follows reparse points. The Store's %LOCALAPPDATA%\Microsoft\WindowsApps\pwsh.exe is an app execution alias whose target directory ACL refuses stat (EACCES), so existsSync missed it and resolution silently fell through to Windows PowerShell 5.1 on hosts whose only PowerShell 7 is a Store install.
Decision
candidateExists accepts a candidate that stats as a file or that lstat sees as a link-shaped reparse point, and resolvePwshPath uses it. Spawning the alias path works because CreateProcess resolves app execution aliases. A dangling link-shaped candidate is accepted so a broken pwsh fails loudly at spawn instead of silently downgrading to 5.1.
Alternatives considered
Probe the WindowsApps package directory directly. The Store package path is versioned and ACL-hidden; hard-coding it duplicates packaging knowledge that PATH plus the alias already owns.
Keep the 5.1 fallback for stat failures. Rejected: it silently runs a different shell than the one installed, which is the defect this note fixes.
Consequences
Store-installed PowerShell 7 now resolves ahead of the 5.1 fallback on Windows; real-file candidates and non-Windows behavior are unchanged. The dangling-symlink unit test pins the stat/lstat split on every platform.
中文
问题
resolvePwshPath 声称 Store 安装经 PATH 解析，但它的存在性探测用的是 existsSync，会对候选做 stat、从而跟随重解析点。Store 的 %LOCALAPPDATA%\Microsoft\WindowsApps\pwsh.exe 是 app execution alias，其目标目录的 ACL 拒绝 stat（EACCES），于是 existsSync 看不到它，解析静默落到 Windows PowerShell 5.1——在这类「唯一的 PowerShell 7 是 Store 安装」的机器上就用了错误的 shell。
决策
candidateExists 接受「stat 为文件」或「lstat 为链接形态重解析点」的候选，resolvePwshPath 改用它。spawn 别名路径可以工作，因为 CreateProcess 会解析 app execution alias。悬空的链接形态候选同样被接受，让损坏的 pwsh 在 spawn 时响亮失败，而不是静默降级到 5.1。
考虑过的替代方案
直接探测 WindowsApps 包目录。 Store 包路径带版本且被 ACL 隐藏；硬编码它只是重复了 PATH 加别名已经拥有的打包知识。
对 stat 失败继续走 5.1 回退。 否决：它静默运行了一个并非所装的 shell，这正是本 note 修复的缺陷。
后果
Windows 上 Store 安装的 PowerShell 7 现在先于 5.1 回退被解析；普通文件候选和非 Windows 平台行为不变。悬空 symlink 单元测试在全部平台上钉住 stat/lstat 的分裂行为。