diff --git a/packages/core/test/kilocode/powershell.test.ts b/packages/core/test/kilocode/powershell.test.ts
new file mode 100644
index 00000000000..5446f448516
--- /dev/null
+++ b/packages/core/test/kilocode/powershell.test.ts
@@ -0,0 +1,73 @@
+import { describe, expect, test } from "bun:test"
+import { existsSync } from "fs"
+import path from "path"
+import { Shell } from "@opencode-ai/core/shell"
+import { which } from "@opencode-ai/core/util/which"
+
+const LEGACY = "C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe"
+
+const knownLocations = () => {
+  const roots = [
+    process.env.ProgramFiles && path.join(process.env.ProgramFiles, "PowerShell", "7"),
+    process.env["ProgramFiles(x86)"] && path.join(process.env["ProgramFiles(x86)"], "PowerShell", "7"),
+    process.env.LOCALAPPDATA && path.join(process.env.LOCALAPPDATA, "Microsoft", "WindowsApps"),
+  ].filter((item): item is string => Boolean(item))
+  return roots.map((root) => path.join(root, "pwsh.exe")).filter((file) => existsSync(file))
+}
+
+const pwshInstalled = () => Boolean(which("pwsh")) || knownLocations().length > 0
+
+// Remove every PATH directory that can resolve pwsh or powershell so detection
+// cannot fall back to PATH lookup and must find installs on its own.
+const withoutPowershellDirs = () =>
+  (process.env.PATH ?? "")
+    .split(path.delimiter)
+    .filter(Boolean)
+    .filter((dir) => !/powershell/i.test(dir) && !existsSync(path.join(dir, "pwsh.exe")))
+    .join(path.delimiter)
+
+function withEnv(env: { PATH?: string; SHELL?: string }, fn: () => void) {
+  const prevPath = process.env.PATH
+  const prevShell = process.env.SHELL
+  if (env.PATH === undefined) delete process.env.PATH
+  else process.env.PATH = env.PATH
+  if (env.SHELL === undefined) delete process.env.SHELL
+  else process.env.SHELL = env.SHELL
+  Shell.preferred.reset()
+  Shell.acceptable.reset()
+  try {
+    fn()
+  } finally {
+    if (prevPath === undefined) delete process.env.PATH
+    else process.env.PATH = prevPath
+    if (prevShell === undefined) delete process.env.SHELL
+    else process.env.SHELL = prevShell
+    Shell.preferred.reset()
+    Shell.acceptable.reset()
+  }
+}
+
+if (process.platform === "win32") {
+  describe("windows powershell selection", () => {
+    test("prefers an installed powershell 7 when pwsh is absent from PATH", () => {
+      if (!pwshInstalled()) return
+      withEnv({ PATH: withoutPowershellDirs(), SHELL: undefined }, () => {
+        expect(Shell.name(Shell.preferred())).toBe("pwsh")
+        expect(Shell.name(Shell.acceptable())).toBe("pwsh")
+      })
+    })
+
+    test("prefers pwsh over legacy 5.1 on the unmodified PATH", () => {
+      if (!pwshInstalled()) return
+      withEnv({ SHELL: undefined }, () => {
+        expect(Shell.name(Shell.preferred())).toBe("pwsh")
+      })
+    })
+
+    test("explicit shell config still overrides detection", () => {
+      if (!existsSync(LEGACY)) return
+      expect(Shell.preferred(LEGACY)).toBe(LEGACY)
+      expect(Shell.acceptable(LEGACY)).toBe(LEGACY)
+    })
+  })
+}