diff --git a/tests/unit/utils.test.ts b/tests/unit/utils.test.ts
new file mode 100644
index 0000000..a3fad4b
--- /dev/null
+++ b/tests/unit/utils.test.ts
@@ -0,0 +1,210 @@
+import { OSUtils, osUtils } from '../../src/utils/osUtils';
+import { ShellUtils, shellUtils } from '../../src/utils/shellUtils';
+import { TemplateUtils, templateUtils } from '../../src/utils/templateUtils';
+import { Layout, Template, TerminalType } from '../../src/models/types';
+
+describe('OSUtils', () => {
+  describe('getPlatform', () => {
+    it('should return current platform', () => {
+      const platform = osUtils.getPlatform();
+      expect(['darwin', 'linux', 'win32']).toContain(platform);
+    });
+  });
+
+  describe('isMacOS', () => {
+    it('should return true on macOS', () => {
+      const isMac = osUtils.isMacOS();
+      expect(typeof isMac).toBe('boolean');
+    });
+  });
+
+  describe('isLinux', () => {
+    it('should return true on Linux', () => {
+      const isLinux = osUtils.isLinux();
+      expect(typeof isLinux).toBe('boolean');
+    });
+  });
+
+  describe('getHomeDir', () => {
+    it('should return home directory', () => {
+      const homeDir = osUtils.getHomeDir();
+      expect(homeDir).toBeTruthy();
+      expect(homeDir.startsWith('/home') || homeDir.startsWith('/Users')).toBe(true);
+    });
+  });
+
+  describe('expandPath', () => {
+    it('should expand tilde to home directory', () => {
+      const home = osUtils.getHomeDir();
+      const expanded = osUtils.expandPath('~/test');
+      expect(expanded).toBe(`${home}/test`);
+    });
+
+    it('should not modify absolute paths', () => {
+      const expanded = osUtils.expandPath('/usr/local/bin');
+      expect(expanded).toBe('/usr/local/bin');
+    });
+  });
+
+  describe('detectTerminalType', () => {
+    it('should detect terminal type based on platform', () => {
+      const terminalType = osUtils.detectTerminalType();
+      expect(['tmux', 'screen', 'iterm2', 'unknown']).toContain(terminalType);
+    });
+  });
+});
+
+describe('ShellUtils', () => {
+  describe('isCommandAvailable', () => {
+    it('should return boolean for valid command', async () => {
+      const available = await shellUtils.isCommandAvailable('ls');
+      expect(typeof available).toBe('boolean');
+    });
+
+    it('should return false for invalid command', async () => {
+      const available = await shellUtils.isCommandAvailable('__invalid_command_12345__');
+      expect(available).toBe(false);
+    });
+  });
+
+  describe('exec', () => {
+    it('should return result object for command', async () => {
+      const result = await shellUtils.exec('echo "test"');
+      expect(typeof result.success).toBe('boolean');
+      expect(typeof result.stdout).toBe('string');
+      expect(typeof result.stderr).toBe('string');
+      expect(typeof result.exitCode).toBe('number');
+    });
+
+    it('should return failure for invalid command', async () => {
+      const result = await shellUtils.exec('__invalid_command_12345__');
+      expect(result.success).toBe(false);
+    });
+  });
+});
+
+describe('TemplateUtils', () => {
+  describe('extractVariables', () => {
+    it('should extract variables from template', () => {
+      const template: Template = {
+        name: 'test',
+        displayName: 'Test',
+        description: 'Test template',
+        variables: [
+          { name: 'PROJECT_DIR', description: 'Project dir', required: true },
+          { name: 'SERVER_URL', description: 'Server URL', required: false },
+        ],
+        layout: {
+          version: '1.0.0',
+          terminalType: 'tmux' as TerminalType,
+          createdAt: '2024-01-01T00:00:00.000Z',
+          updatedAt: '2024-01-01T00:00:00.000Z',
+          session: {
+            id: 's1',
+            name: 'test',
+            windows: [],
+            activeWindowIndex: 0,
+          },
+        },
+      };
+
+      const layoutWithVars: Layout = {
+        ...template.layout,
+        session: {
+          ...template.layout.session,
+          windows: [
+            {
+              id: 'w1',
+              index: 0,
+              name: 'main',
+              panes: [
+                {
+                  id: 'p1',
+                  index: 0,
+                  layout: { x: 0, y: 0, width: 80, height: 24 },
+                  command: 'cd ${PROJECT_DIR} && npm run dev',
+                  cwd: '${PROJECT_DIR}',
+                },
+              ],
+            },
+          ],
+        },
+      };
+
+      const variables = templateUtils.extractVariables({ ...template, layout: layoutWithVars });
+      expect(variables).toContain('PROJECT_DIR');
+    });
+  });
+
+  describe('substituteVariables', () => {
+    it('should substitute variables in layout', () => {
+      const layout: Layout = {
+        version: '1.0.0',
+        terminalType: 'tmux' as TerminalType,
+        createdAt: '2024-01-01T00:00:00.000Z',
+        updatedAt: '2024-01-01T00:00:00.000Z',
+        session: {
+          id: 's1',
+          name: 'test',
+          windows: [
+            {
+              id: 'w1',
+              index: 0,
+              name: 'main',
+              panes: [
+                {
+                  id: 'p1',
+                  index: 0,
+                  layout: { x: 0, y: 0, width: 80, height: 24 },
+                  command: 'cd ${PROJECT_DIR} && npm run dev',
+                  cwd: '${PROJECT_DIR}',
+                },
+              ],
+            },
+          ],
+          activeWindowIndex: 0,
+        },
+      };
+
+      const variables: Record<string, string> = {
+        PROJECT_DIR: '/home/user/projects/myapp',
+      };
+
+      const substituted = templateUtils.substituteVariables(layout, variables);
+      expect(substituted.session.windows[0].panes[0].command).toBe(
+        'cd /home/user/projects/myapp && npm run dev'
+      );
+      expect(substituted.session.windows[0].panes[0].cwd).toBe('/home/user/projects/myapp');
+    });
+  });
+
+  describe('validateTemplateVariables', () => {
+    it('should return missing required variables', () => {
+      const template: Template = {
+        name: 'test',
+        displayName: 'Test',
+        description: 'Test template',
+        variables: [
+          { name: 'REQUIRED_VAR', description: 'Required', required: true },
+          { name: 'OPTIONAL_VAR', description: 'Optional', required: false, defaultValue: 'default' },
+        ],
+        layout: {
+          version: '1.0.0',
+          terminalType: 'tmux' as TerminalType,
+          createdAt: '2024-01-01T00:00:00.000Z',
+          updatedAt: '2024-01-01T00:00:00.000Z',
+          session: {
+            id: 's1',
+            name: 'test',
+            windows: [],
+            activeWindowIndex: 0,
+          },
+        },
+      };
+
+      const missing = templateUtils.validateTemplateVariables(template, {});
+      expect(missing).toContain('REQUIRED_VAR');
+      expect(missing).not.toContain('OPTIONAL_VAR');
+    });
+  });
+});