Merge pull request #3339 from Qiiks/fix/shell-detection-shell-before-psmodulepath

fix(shell-env): check SHELL before PSModulePath for shell detection

src/shared/shell-env.test.ts

@@ -45,7 +45,8 @@ describe("shell-env", () => {
       expect(result).toBe("unix")
     })
 
-    test("#given PSModulePath is set #when detectShellType is called #then returns powershell", () => {
+    test("#given PSModulePath is set without SHELL #when detectShellType is called #then returns powershell", () => {
+      delete process.env.SHELL
       process.env.PSModulePath = "C:\\Program Files\\PowerShell\\Modules"
       Object.defineProperty(process, "platform", { value: "win32" })
 
@@ -74,14 +75,24 @@ describe("shell-env", () => {
       expect(result).toBe("unix")
     })
 
-    test("#given PSModulePath takes priority over SHELL #when both are set #then returns powershell", () => {
+    test("#given SHELL takes priority over PSModulePath #when both are set #then returns unix", () => {
       process.env.PSModulePath = "C:\\Program Files\\PowerShell\\Modules"
       process.env.SHELL = "/bin/bash"
       Object.defineProperty(process, "platform", { value: "win32" })
 
       const result = detectShellType()
 
-      expect(result).toBe("powershell")
+      expect(result).toBe("unix")
+    })
+
+    test("#given SHELL set to Git Bash on Windows with PSModulePath #when detectShellType is called #then returns unix", () => {
+      process.env.PSModulePath = "C:\\Program Files\\PowerShell\\Modules"
+      process.env.SHELL = "C:\\Program Files\\Git\\bin\\bash.exe"
+      Object.defineProperty(process, "platform", { value: "win32" })
+
+      const result = detectShellType()
+
+      expect(result).toBe("unix")
     })
   })
 

src/shared/shell-env.ts

@@ -4,15 +4,15 @@ export type ShellType = "unix" | "powershell" | "cmd" | "csh"
  * Detect the current shell type based on environment variables.
  * 
  * Detection priority:
- * 1. PSModulePath → PowerShell
- * 2. SHELL env var → Unix shell
+ * 1. SHELL env var → Unix shell (explicit user choice takes precedence)
+ * 2. PSModulePath → PowerShell
  * 3. Platform fallback → win32: cmd, others: unix
+ * 
+ * Note: SHELL is checked before PSModulePath because on Windows, PSModulePath
+ * is always set by the system even when the active shell is Git Bash or WSL.
+ * An explicit SHELL variable indicates the user's chosen shell overrides that.
  */
 export function detectShellType(): ShellType {
-  if (process.env.PSModulePath) {
-    return "powershell"
-  }
-
   if (process.env.SHELL) {
     const shell = process.env.SHELL
     if (shell.includes("csh") || shell.includes("tcsh")) {
@@ -21,6 +21,10 @@ export function detectShellType(): ShellType {
     return "unix"
   }
 
+  if (process.env.PSModulePath) {
+    return "powershell"
+  }
+
   return process.platform === "win32" ? "cmd" : "unix"
 }