fix(task): convert PATH to /cygdrive form for Cygwin bash tasks

docs/troubleshooting.md

@@ -193,6 +193,28 @@ shell = '"C:\Program Files\Git\bin\bash.exe" -c'
 
 (On macOS/Linux, `shell` follows POSIX quoting rules instead.)
 
+#### Cygwin
+
+mise also detects Cygwin bash (by a `cygwin` / `cygwin64` / `cygwin32` segment in its path) and
+converts PATH using Cygwin's `/cygdrive/c/...` form instead of Git Bash's `/c/...`,
+so binaries on PATH resolve correctly. Point `MISE_BASH_PATH` at your Cygwin bash so
+the intended one is used:
+
+```powershell
+$env:MISE_BASH_PATH = "C:\cygwin64\bin\bash.exe"
+```
+
+If you changed the `cygdrive` prefix in `/etc/fstab` (the default is `/cygdrive`),
+set `MISE_CYGDRIVE_PREFIX` to match — mise does not read `/etc/fstab`:
+
+```powershell
+# e.g. for an fstab that mounts drives under /mnt
+$env:MISE_CYGDRIVE_PREFIX = "/mnt"
+```
+
+The prefix must be absolute (start with `/`); a relative value like `mnt` is rejected
+with a warning and the default `/cygdrive` is used instead.
+
 ## mise isn't working when calling from tmux or another shell initialization script
 
 `mise activate` will not update PATH until the shell prompt is displayed. So if you need to access a

e2e-win/task.Tests.ps1

@@ -108,4 +108,66 @@ esac
             Remove-Item -Path "$TestDrive\mise.path_repro.toml" -ErrorAction SilentlyContinue
         }
     }
+
+    It 'converts PATH to /cygdrive form for a Cygwin bash subshell task' {
+        # Cygwin resolves drives via `/cygdrive/c/...`, not Git Bash's `/c/...`.
+        # When mise detects a Cygwin bash (here pinned via MISE_BASH_PATH), the
+        # task's PATH must use the `/cygdrive/` form or commands won't resolve.
+        # Skipped unless Cygwin is actually installed, since CI runners lack it.
+
+        $cygwinBash = "C:\cygwin64\bin\bash.exe"
+        if (-not (Test-Path $cygwinBash)) {
+            Set-ItResult -Skipped -Because "Cygwin bash not installed at $cygwinBash"
+            return
+        }
+
+        @'
+[tasks.cygdrive_repro]
+shell = "bash -c"
+run = '''
+case "$PATH" in
+  */cygdrive/*)
+    echo "PATH-cygdrive-style"
+    ;;
+  *)
+    echo "PATH-not-cygdrive"
+    ;;
+esac
+'''
+'@ | Out-File -FilePath "mise.cygdrive_repro.toml" -Encoding utf8NoBOM
+
+        # Save and restore the env vars we override so a dev machine's real
+        # settings (a developer may export MISE_BASH_PATH / MISE_CYGDRIVE_PREFIX)
+        # and later tests are not disturbed. Pin MISE_CYGDRIVE_PREFIX to the
+        # default so the `/cygdrive` assertion holds even when the caller has
+        # exported a custom prefix such as `/mnt` (which the feature honors).
+        $oldConfig = $env:MISE_CONFIG_FILE
+        $oldBashPath = $env:MISE_BASH_PATH
+        $oldCygPrefix = $env:MISE_CYGDRIVE_PREFIX
+        $env:MISE_CONFIG_FILE = "$TestDrive\mise.cygdrive_repro.toml"
+        $env:MISE_BASH_PATH = $cygwinBash
+        $env:MISE_CYGDRIVE_PREFIX = "/cygdrive"
+        try {
+            $output = mise run cygdrive_repro 2>&1 | Select -Last 1
+            $output | Should -Be 'PATH-cygdrive-style'
+        }
+        finally {
+            if ($null -eq $oldConfig) {
+                Remove-Item -Path Env:\MISE_CONFIG_FILE -ErrorAction SilentlyContinue
+            } else {
+                $env:MISE_CONFIG_FILE = $oldConfig
+            }
+            if ($null -eq $oldBashPath) {
+                Remove-Item -Path Env:\MISE_BASH_PATH -ErrorAction SilentlyContinue
+            } else {
+                $env:MISE_BASH_PATH = $oldBashPath
+            }
+            if ($null -eq $oldCygPrefix) {
+                Remove-Item -Path Env:\MISE_CYGDRIVE_PREFIX -ErrorAction SilentlyContinue
+            } else {
+                $env:MISE_CYGDRIVE_PREFIX = $oldCygPrefix
+            }
+            Remove-Item -Path "$TestDrive\mise.cygdrive_repro.toml" -ErrorAction SilentlyContinue
+        }
+    }
 }