fix bun path for workspace installs

src/workspace-package-manager.test.ts

@@ -23,6 +23,14 @@ import {
 
 let tempRoot: string;
 
+function expectedBunExecutable(): string {
+  if (path.basename(process.execPath) === 'bun') {
+    return process.execPath;
+  }
+  const homeBun = path.join(os.homedir(), '.bun', 'bin', 'bun');
+  return fs.existsSync(homeBun) ? homeBun : 'bun';
+}
+
 beforeEach(() => {
   tempRoot = fs.mkdtempSync(path.join(os.tmpdir(), 'ejclaw-pkgmgr-'));
   execFileSyncMock.mockReset();
@@ -105,11 +113,35 @@ describe('workspace package manager detection', () => {
       commandText: 'corepack pnpm install --frozen-lockfile',
     });
     expect(buildWorkspaceScriptCommand(bunRepo, 'build')).toMatchObject({
-      file: 'bun',
+      file: expectedBunExecutable(),
       args: ['run', 'build'],
       commandText: 'bun run build',
     });
   });
+
+  it('uses an absolute Bun executable when building Bun workspace commands', () => {
+    const repoDir = path.join(tempRoot, 'bun-path');
+    fs.mkdirSync(repoDir, { recursive: true });
+    fs.writeFileSync(
+      path.join(repoDir, 'package.json'),
+      JSON.stringify({
+        packageManager: 'bun@1.3.13',
+        scripts: { build: 'tsc' },
+      }),
+    );
+    fs.writeFileSync(path.join(repoDir, 'bun.lock'), '');
+
+    const scriptCommand = buildWorkspaceScriptCommand(repoDir, 'build');
+    const installCommand = resolveWorkspaceInstallCommand(repoDir);
+
+    expect(path.isAbsolute(scriptCommand.file)).toBe(true);
+    expect(scriptCommand.file).toBe(expectedBunExecutable());
+    expect(installCommand).toMatchObject({
+      file: expectedBunExecutable(),
+      args: ['install', '--frozen-lockfile'],
+      commandText: 'bun install --frozen-lockfile',
+    });
+  });
 });
 
 describe('workspace dependency installs', () => {