support hidden folders

base-action/src/install-plugins.ts

@@ -13,11 +13,16 @@ const MARKETPLACE_URL_REGEX =
  * @returns true if the input is a local path, false if it's a URL
  */
 function isLocalPath(input: string): boolean {
-  // Local paths start with ./, ../, /, or a drive letter (Windows)
+  // Local paths start with:
+  // - ./ or ../ (relative paths)
+  // - / (Unix absolute paths)
+  // - .something/ (hidden folders like .claude-marketplace/)
+  // - Drive letter (Windows paths like C:\)
   return (
     input.startsWith("./") ||
     input.startsWith("../") ||
     input.startsWith("/") ||
+    /^\.[a-zA-Z0-9_-]+[\\\/]/.test(input) || // Hidden folders: .plugins/, .cache/
     /^[a-zA-Z]:[\\\/]/.test(input)
   );
 }

base-action/test/install-plugins.test.ts

@@ -703,4 +703,30 @@ describe("installPlugins", () => {
       { stdio: "inherit" },
     );
   });
+
+  test("should accept hidden folder path (.folder-name/)", async () => {
+    const spy = createMockSpawn();
+    await installPlugins(".my-plugins/marketplace", "test-plugin");
+
+    expect(spy).toHaveBeenCalledTimes(2);
+    expect(spy).toHaveBeenNthCalledWith(
+      1,
+      "claude",
+      ["plugin", "marketplace", "add", ".my-plugins/marketplace"],
+      { stdio: "inherit" },
+    );
+  });
+
+  test("should accept hidden folder path with Windows backslash", async () => {
+    const spy = createMockSpawn();
+    await installPlugins(".hidden-folder\\marketplace", "test-plugin");
+
+    expect(spy).toHaveBeenCalledTimes(2);
+    expect(spy).toHaveBeenNthCalledWith(
+      1,
+      "claude",
+      ["plugin", "marketplace", "add", ".hidden-folder\\marketplace"],
+      { stdio: "inherit" },
+    );
+  });
 });