diff --git a/__tests__/ai/nlp/intent-classifier.test.ts b/__tests__/ai/nlp/intent-classifier.test.ts
new file mode 100644
index 0000000..91a068b
--- /dev/null
+++ b/__tests__/ai/nlp/intent-classifier.test.ts
@@ -0,0 +1,204 @@
+import { IntentClassifier } from '../../../src/ai/nlp/intent-classifier.js';
+
+describe('IntentClassifier', () => {
+    let classifier: IntentClassifier;
+
+    beforeEach(() => {
+        classifier = new IntentClassifier();
+    });
+
+    describe('Basic Intent Classification', () => {
+        it('should classify turn_on commands', async () => {
+            const testCases = [
+                {
+                    input: 'turn on the living room light',
+                    entities: { parameters: {}, primary_target: 'light.living_room' },
+                    expectedAction: 'turn_on'
+                },
+                {
+                    input: 'switch on the kitchen lights',
+                    entities: { parameters: {}, primary_target: 'light.kitchen' },
+                    expectedAction: 'turn_on'
+                },
+                {
+                    input: 'enable the bedroom lamp',
+                    entities: { parameters: {}, primary_target: 'light.bedroom' },
+                    expectedAction: 'turn_on'
+                }
+            ];
+
+            for (const test of testCases) {
+                const result = await classifier.classify(test.input, test.entities);
+                expect(result.action).toBe(test.expectedAction);
+                expect(result.target).toBe(test.entities.primary_target);
+                expect(result.confidence).toBeGreaterThan(0.5);
+            }
+        });
+
+        it('should classify turn_off commands', async () => {
+            const testCases = [
+                {
+                    input: 'turn off the living room light',
+                    entities: { parameters: {}, primary_target: 'light.living_room' },
+                    expectedAction: 'turn_off'
+                },
+                {
+                    input: 'switch off the kitchen lights',
+                    entities: { parameters: {}, primary_target: 'light.kitchen' },
+                    expectedAction: 'turn_off'
+                },
+                {
+                    input: 'disable the bedroom lamp',
+                    entities: { parameters: {}, primary_target: 'light.bedroom' },
+                    expectedAction: 'turn_off'
+                }
+            ];
+
+            for (const test of testCases) {
+                const result = await classifier.classify(test.input, test.entities);
+                expect(result.action).toBe(test.expectedAction);
+                expect(result.target).toBe(test.entities.primary_target);
+                expect(result.confidence).toBeGreaterThan(0.5);
+            }
+        });
+
+        it('should classify set commands with parameters', async () => {
+            const testCases = [
+                {
+                    input: 'set the living room light brightness to 50',
+                    entities: {
+                        parameters: { brightness: 50 },
+                        primary_target: 'light.living_room'
+                    },
+                    expectedAction: 'set'
+                },
+                {
+                    input: 'change the temperature to 72',
+                    entities: {
+                        parameters: { temperature: 72 },
+                        primary_target: 'climate.living_room'
+                    },
+                    expectedAction: 'set'
+                },
+                {
+                    input: 'adjust the kitchen light color to red',
+                    entities: {
+                        parameters: { color: 'red' },
+                        primary_target: 'light.kitchen'
+                    },
+                    expectedAction: 'set'
+                }
+            ];
+
+            for (const test of testCases) {
+                const result = await classifier.classify(test.input, test.entities);
+                expect(result.action).toBe(test.expectedAction);
+                expect(result.target).toBe(test.entities.primary_target);
+                expect(result.parameters).toEqual(test.entities.parameters);
+                expect(result.confidence).toBeGreaterThan(0.5);
+            }
+        });
+
+        it('should classify query commands', async () => {
+            const testCases = [
+                {
+                    input: 'what is the living room temperature',
+                    entities: { parameters: {}, primary_target: 'sensor.living_room_temperature' },
+                    expectedAction: 'query'
+                },
+                {
+                    input: 'get the kitchen light status',
+                    entities: { parameters: {}, primary_target: 'light.kitchen' },
+                    expectedAction: 'query'
+                },
+                {
+                    input: 'show me the front door camera',
+                    entities: { parameters: {}, primary_target: 'camera.front_door' },
+                    expectedAction: 'query'
+                }
+            ];
+
+            for (const test of testCases) {
+                const result = await classifier.classify(test.input, test.entities);
+                expect(result.action).toBe(test.expectedAction);
+                expect(result.target).toBe(test.entities.primary_target);
+                expect(result.confidence).toBeGreaterThan(0.5);
+            }
+        });
+    });
+
+    describe('Edge Cases and Error Handling', () => {
+        it('should handle empty input gracefully', async () => {
+            const result = await classifier.classify('', { parameters: {}, primary_target: '' });
+            expect(result.action).toBe('unknown');
+            expect(result.confidence).toBeLessThan(0.5);
+        });
+
+        it('should handle unknown commands with low confidence', async () => {
+            const result = await classifier.classify(
+                'do something random',
+                { parameters: {}, primary_target: 'light.living_room' }
+            );
+            expect(result.action).toBe('unknown');
+            expect(result.confidence).toBeLessThan(0.5);
+        });
+
+        it('should handle missing entities gracefully', async () => {
+            const result = await classifier.classify(
+                'turn on the lights',
+                { parameters: {}, primary_target: '' }
+            );
+            expect(result.action).toBe('turn_on');
+            expect(result.target).toBe('');
+        });
+    });
+
+    describe('Confidence Calculation', () => {
+        it('should assign higher confidence to exact matches', async () => {
+            const exactMatch = await classifier.classify(
+                'turn on',
+                { parameters: {}, primary_target: 'light.living_room' }
+            );
+            const partialMatch = await classifier.classify(
+                'please turn on the lights if possible',
+                { parameters: {}, primary_target: 'light.living_room' }
+            );
+            expect(exactMatch.confidence).toBeGreaterThan(partialMatch.confidence);
+        });
+
+        it('should boost confidence for polite phrases', async () => {
+            const politeRequest = await classifier.classify(
+                'please turn on the lights',
+                { parameters: {}, primary_target: 'light.living_room' }
+            );
+            const basicRequest = await classifier.classify(
+                'turn on the lights',
+                { parameters: {}, primary_target: 'light.living_room' }
+            );
+            expect(politeRequest.confidence).toBeGreaterThan(basicRequest.confidence);
+        });
+    });
+
+    describe('Context Inference', () => {
+        it('should infer set action when parameters are present', async () => {
+            const result = await classifier.classify(
+                'lights at 50%',
+                {
+                    parameters: { brightness: 50 },
+                    primary_target: 'light.living_room'
+                }
+            );
+            expect(result.action).toBe('set');
+            expect(result.parameters).toHaveProperty('brightness', 50);
+        });
+
+        it('should infer query action for question-like inputs', async () => {
+            const result = await classifier.classify(
+                'how warm is it',
+                { parameters: {}, primary_target: 'sensor.temperature' }
+            );
+            expect(result.action).toBe('query');
+            expect(result.confidence).toBeGreaterThan(0.5);
+        });
+    });
+}); 
\ No newline at end of file
diff --git a/__tests__/security/middleware.test.ts b/__tests__/security/middleware.test.ts
new file mode 100644
index 0000000..e05fc57
--- /dev/null
+++ b/__tests__/security/middleware.test.ts
@@ -0,0 +1,248 @@
+import { Request, Response } from 'express';
+import {
+    validateRequest,
+    sanitizeInput,
+    errorHandler,
+    rateLimiter,
+    securityHeaders
+} from '../../src/security/index.js';
+
+interface MockRequest extends Partial<Request> {
+    headers: Record<string, string>;
+    is: jest.Mock;
+}
+
+describe('Security Middleware', () => {
+    let mockRequest: MockRequest;
+    let mockResponse: Partial<Response>;
+    let mockNext: jest.Mock;
+
+    beforeEach(() => {
+        mockRequest = {
+            method: 'POST',
+            headers: {
+                'content-type': 'application/json',
+                'authorization': 'Bearer validToken'
+            },
+            is: jest.fn().mockReturnValue(true),
+            body: { test: 'data' }
+        };
+        mockResponse = {
+            status: jest.fn().mockReturnThis(),
+            json: jest.fn(),
+            setHeader: jest.fn(),
+            set: jest.fn()
+        };
+        mockNext = jest.fn();
+    });
+
+    describe('Request Validation', () => {
+        it('should pass valid requests', () => {
+            validateRequest(
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+            expect(mockNext).toHaveBeenCalled();
+            expect(mockResponse.status).not.toHaveBeenCalled();
+        });
+
+        it('should reject requests with invalid content type', () => {
+            mockRequest.is = jest.fn().mockReturnValue(false);
+            validateRequest(
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+            expect(mockResponse.status).toHaveBeenCalledWith(415);
+            expect(mockResponse.json).toHaveBeenCalledWith({
+                error: 'Unsupported Media Type - Content-Type must be application/json'
+            });
+        });
+
+        it('should reject requests without authorization', () => {
+            mockRequest.headers = {};
+            validateRequest(
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+            expect(mockResponse.status).toHaveBeenCalledWith(401);
+            expect(mockResponse.json).toHaveBeenCalledWith({
+                error: 'Invalid or expired token'
+            });
+        });
+
+        it('should reject requests with invalid token', () => {
+            mockRequest.headers.authorization = 'Bearer invalid.token.format';
+            validateRequest(
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+            expect(mockResponse.status).toHaveBeenCalledWith(401);
+        });
+
+        it('should handle GET requests without body validation', () => {
+            mockRequest.method = 'GET';
+            mockRequest.body = undefined;
+            validateRequest(
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+            expect(mockNext).toHaveBeenCalled();
+        });
+    });
+
+    describe('Input Sanitization', () => {
+        it('should remove HTML tags from request body', () => {
+            mockRequest.body = {
+                text: '<script>alert("xss")</script>',
+                nested: {
+                    html: '<img src="x" onerror="alert(1)">'
+                }
+            };
+
+            sanitizeInput(
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+
+            expect(mockRequest.body.text).not.toContain('<script>');
+            expect(mockRequest.body.nested.html).not.toContain('<img');
+            expect(mockNext).toHaveBeenCalled();
+        });
+
+        it('should handle non-object body', () => {
+            mockRequest.body = 'plain text';
+            sanitizeInput(
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+            expect(mockRequest.body).toBe('plain text');
+            expect(mockNext).toHaveBeenCalled();
+        });
+
+        it('should handle nested objects', () => {
+            mockRequest.body = {
+                level1: {
+                    level2: {
+                        text: '<p>test</p>'
+                    }
+                }
+            };
+
+            sanitizeInput(
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+
+            expect(mockRequest.body.level1.level2.text).not.toContain('<p>');
+            expect(mockNext).toHaveBeenCalled();
+        });
+
+        it('should preserve safe content', () => {
+            mockRequest.body = {
+                text: 'Safe text without HTML',
+                number: 42,
+                boolean: true
+            };
+
+            const originalBody = { ...mockRequest.body };
+            sanitizeInput(
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+
+            expect(mockRequest.body).toEqual(originalBody);
+            expect(mockNext).toHaveBeenCalled();
+        });
+    });
+
+    describe('Error Handler', () => {
+        const originalEnv = process.env.NODE_ENV;
+
+        afterAll(() => {
+            process.env.NODE_ENV = originalEnv;
+        });
+
+        it('should handle errors in production mode', () => {
+            process.env.NODE_ENV = 'production';
+            const error = new Error('Test error');
+
+            errorHandler(
+                error,
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+
+            expect(mockResponse.status).toHaveBeenCalledWith(500);
+            expect(mockResponse.json).toHaveBeenCalledWith({
+                error: 'Internal Server Error',
+                message: undefined
+            });
+        });
+
+        it('should include error details in development mode', () => {
+            process.env.NODE_ENV = 'development';
+            const error = new Error('Test error');
+
+            errorHandler(
+                error,
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+
+            expect(mockResponse.status).toHaveBeenCalledWith(500);
+            expect(mockResponse.json).toHaveBeenCalledWith({
+                error: 'Internal Server Error',
+                message: 'Test error'
+            });
+        });
+
+        it('should handle non-Error objects', () => {
+            const error = 'String error message';
+
+            errorHandler(
+                error as any,
+                mockRequest as Request,
+                mockResponse as Response,
+                mockNext
+            );
+
+            expect(mockResponse.status).toHaveBeenCalledWith(500);
+        });
+    });
+
+    describe('Rate Limiter', () => {
+        it('should be configured with correct options', () => {
+            expect(rateLimiter).toBeDefined();
+            const middleware = rateLimiter as any;
+            expect(middleware.windowMs).toBeDefined();
+            expect(middleware.max).toBeDefined();
+        });
+    });
+
+    describe('Security Headers', () => {
+        it('should be configured with secure defaults', () => {
+            expect(securityHeaders).toBeDefined();
+            const middleware = securityHeaders as any;
+            expect(middleware.getDefaultDirectives).toBeDefined();
+        });
+
+        it('should set appropriate security headers', () => {
+            const mockRes = {
+                setHeader: jest.fn()
+            };
+            securityHeaders(mockRequest as Request, mockRes as any, mockNext);
+            expect(mockRes.setHeader).toHaveBeenCalled();
+        });
+    });
+}); 
\ No newline at end of file
diff --git a/__tests__/security/token-manager.test.ts b/__tests__/security/token-manager.test.ts
new file mode 100644
index 0000000..bd4fc6b
--- /dev/null
+++ b/__tests__/security/token-manager.test.ts
@@ -0,0 +1,127 @@
+import { TokenManager } from '../../src/security/index.js';
+
+describe('TokenManager', () => {
+    const validToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiZXhwIjoxNzE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c';
+    const expiredToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiZXhwIjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c';
+    const encryptionKey = 'test_encryption_key_12345';
+
+    describe('Token Encryption/Decryption', () => {
+        it('should encrypt and decrypt tokens successfully', () => {
+            const encrypted = TokenManager.encryptToken(validToken, encryptionKey);
+            const decrypted = TokenManager.decryptToken(encrypted, encryptionKey);
+            expect(decrypted).toBe(validToken);
+        });
+
+        it('should generate different encrypted values for same token', () => {
+            const encrypted1 = TokenManager.encryptToken(validToken, encryptionKey);
+            const encrypted2 = TokenManager.encryptToken(validToken, encryptionKey);
+            expect(encrypted1).not.toBe(encrypted2);
+        });
+
+        it('should handle empty tokens', () => {
+            expect(() => TokenManager.encryptToken('', encryptionKey)).toThrow();
+        });
+
+        it('should handle empty encryption keys', () => {
+            expect(() => TokenManager.encryptToken(validToken, '')).toThrow();
+        });
+
+        it('should fail decryption with wrong key', () => {
+            const encrypted = TokenManager.encryptToken(validToken, encryptionKey);
+            expect(() => TokenManager.decryptToken(encrypted, 'wrong_key')).toThrow();
+        });
+    });
+
+    describe('Token Validation', () => {
+        it('should validate correct tokens', () => {
+            expect(TokenManager.validateToken(validToken)).toBe(true);
+        });
+
+        it('should reject expired tokens', () => {
+            expect(TokenManager.validateToken(expiredToken)).toBe(false);
+        });
+
+        it('should reject malformed tokens', () => {
+            const malformedTokens = [
+                'not.a.token',
+                'invalid-token-format',
+                'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9',
+                '',
+                'null',
+                'undefined'
+            ];
+
+            malformedTokens.forEach(token => {
+                expect(TokenManager.validateToken(token)).toBe(false);
+            });
+        });
+
+        it('should reject tokens with invalid signature', () => {
+            const tamperedToken = validToken.slice(0, -1) + 'X';
+            expect(TokenManager.validateToken(tamperedToken)).toBe(false);
+        });
+
+        it('should handle tokens with missing expiration', () => {
+            const tokenWithoutExp = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIn0.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c';
+            expect(TokenManager.validateToken(tokenWithoutExp)).toBe(true);
+        });
+    });
+
+    describe('Security Features', () => {
+        it('should use secure encryption algorithm', () => {
+            const encrypted = TokenManager.encryptToken(validToken, encryptionKey);
+            expect(encrypted).toMatch(/^[A-Za-z0-9+/=]+$/); // Base64 format
+            expect(encrypted.length).toBeGreaterThan(validToken.length); // Should include IV and tag
+        });
+
+        it('should prevent token tampering', () => {
+            const encrypted = TokenManager.encryptToken(validToken, encryptionKey);
+            const tampered = encrypted.slice(0, -1) + 'X';
+            expect(() => TokenManager.decryptToken(tampered, encryptionKey)).toThrow();
+        });
+
+        it('should use unique IVs for each encryption', () => {
+            const encrypted1 = TokenManager.encryptToken(validToken, encryptionKey);
+            const encrypted2 = TokenManager.encryptToken(validToken, encryptionKey);
+            const encrypted3 = TokenManager.encryptToken(validToken, encryptionKey);
+
+            // Each encryption should be different due to unique IVs
+            expect(new Set([encrypted1, encrypted2, encrypted3]).size).toBe(3);
+        });
+
+        it('should handle large tokens', () => {
+            const largeToken = validToken.repeat(10); // Create a much larger token
+            const encrypted = TokenManager.encryptToken(largeToken, encryptionKey);
+            const decrypted = TokenManager.decryptToken(encrypted, encryptionKey);
+            expect(decrypted).toBe(largeToken);
+        });
+    });
+
+    describe('Error Handling', () => {
+        it('should throw descriptive errors for invalid inputs', () => {
+            expect(() => TokenManager.encryptToken(null as any, encryptionKey))
+                .toThrow(/invalid/i);
+            expect(() => TokenManager.encryptToken(validToken, null as any))
+                .toThrow(/invalid/i);
+            expect(() => TokenManager.decryptToken('invalid-base64', encryptionKey))
+                .toThrow(/invalid/i);
+        });
+
+        it('should handle corrupted encrypted data', () => {
+            const encrypted = TokenManager.encryptToken(validToken, encryptionKey);
+            const corrupted = encrypted.substring(10); // Remove part of the encrypted data
+            expect(() => TokenManager.decryptToken(corrupted, encryptionKey))
+                .toThrow();
+        });
+
+        it('should handle invalid base64 input', () => {
+            expect(() => TokenManager.decryptToken('not-base64!@#$', encryptionKey))
+                .toThrow(/invalid/i);
+        });
+
+        it('should handle undefined and null inputs', () => {
+            expect(() => TokenManager.validateToken(undefined as any)).toBe(false);
+            expect(() => TokenManager.validateToken(null as any)).toBe(false);
+        });
+    });
+}); 
\ No newline at end of file
diff --git a/__tests__/tools/tool-registry.test.ts b/__tests__/tools/tool-registry.test.ts
new file mode 100644
index 0000000..d857d39
--- /dev/null
+++ b/__tests__/tools/tool-registry.test.ts
@@ -0,0 +1,204 @@
+import { ToolRegistry, ToolCategory, EnhancedTool } from '../../src/tools/index.js';
+
+describe('ToolRegistry', () => {
+    let registry: ToolRegistry;
+    let mockTool: EnhancedTool;
+
+    beforeEach(() => {
+        registry = new ToolRegistry();
+        mockTool = {
+            name: 'test_tool',
+            description: 'A test tool',
+            metadata: {
+                category: ToolCategory.DEVICE,
+                platform: 'test',
+                version: '1.0.0',
+                caching: {
+                    enabled: true,
+                    ttl: 1000
+                }
+            },
+            execute: jest.fn().mockResolvedValue({ success: true }),
+            validate: jest.fn().mockResolvedValue(true),
+            preExecute: jest.fn().mockResolvedValue(undefined),
+            postExecute: jest.fn().mockResolvedValue(undefined)
+        };
+    });
+
+    describe('Tool Registration', () => {
+        it('should register a tool successfully', () => {
+            registry.registerTool(mockTool);
+            const retrievedTool = registry.getTool('test_tool');
+            expect(retrievedTool).toBe(mockTool);
+        });
+
+        it('should categorize tools correctly', () => {
+            registry.registerTool(mockTool);
+            const deviceTools = registry.getToolsByCategory(ToolCategory.DEVICE);
+            expect(deviceTools).toContain(mockTool);
+        });
+
+        it('should handle multiple tools in the same category', () => {
+            const mockTool2 = {
+                ...mockTool,
+                name: 'test_tool_2'
+            };
+            registry.registerTool(mockTool);
+            registry.registerTool(mockTool2);
+            const deviceTools = registry.getToolsByCategory(ToolCategory.DEVICE);
+            expect(deviceTools).toHaveLength(2);
+            expect(deviceTools).toContain(mockTool);
+            expect(deviceTools).toContain(mockTool2);
+        });
+    });
+
+    describe('Tool Execution', () => {
+        it('should execute a tool with all hooks', async () => {
+            registry.registerTool(mockTool);
+            await registry.executeTool('test_tool', { param: 'value' });
+
+            expect(mockTool.validate).toHaveBeenCalledWith({ param: 'value' });
+            expect(mockTool.preExecute).toHaveBeenCalledWith({ param: 'value' });
+            expect(mockTool.execute).toHaveBeenCalledWith({ param: 'value' });
+            expect(mockTool.postExecute).toHaveBeenCalled();
+        });
+
+        it('should throw error for non-existent tool', async () => {
+            await expect(registry.executeTool('non_existent', {}))
+                .rejects.toThrow('Tool non_existent not found');
+        });
+
+        it('should handle validation failure', async () => {
+            mockTool.validate = jest.fn().mockResolvedValue(false);
+            registry.registerTool(mockTool);
+
+            await expect(registry.executeTool('test_tool', {}))
+                .rejects.toThrow('Invalid parameters');
+        });
+
+        it('should execute without optional hooks', async () => {
+            const simpleTool: EnhancedTool = {
+                name: 'simple_tool',
+                description: 'A simple tool',
+                metadata: {
+                    category: ToolCategory.SYSTEM,
+                    platform: 'test',
+                    version: '1.0.0'
+                },
+                execute: jest.fn().mockResolvedValue({ success: true })
+            };
+
+            registry.registerTool(simpleTool);
+            const result = await registry.executeTool('simple_tool', {});
+            expect(result).toEqual({ success: true });
+        });
+    });
+
+    describe('Caching', () => {
+        it('should cache tool results when enabled', async () => {
+            registry.registerTool(mockTool);
+            const params = { test: 'value' };
+
+            // First execution
+            await registry.executeTool('test_tool', params);
+            expect(mockTool.execute).toHaveBeenCalledTimes(1);
+
+            // Second execution within TTL
+            await registry.executeTool('test_tool', params);
+            expect(mockTool.execute).toHaveBeenCalledTimes(1);
+        });
+
+        it('should not cache results when disabled', async () => {
+            const uncachedTool: EnhancedTool = {
+                ...mockTool,
+                metadata: {
+                    ...mockTool.metadata,
+                    caching: {
+                        enabled: false,
+                        ttl: 1000
+                    }
+                }
+            };
+
+            registry.registerTool(uncachedTool);
+            const params = { test: 'value' };
+
+            // Multiple executions
+            await registry.executeTool('test_tool', params);
+            await registry.executeTool('test_tool', params);
+
+            expect(uncachedTool.execute).toHaveBeenCalledTimes(2);
+        });
+
+        it('should expire cache after TTL', async () => {
+            mockTool.metadata.caching!.ttl = 100; // Short TTL for testing
+            registry.registerTool(mockTool);
+            const params = { test: 'value' };
+
+            // First execution
+            await registry.executeTool('test_tool', params);
+
+            // Wait for cache to expire
+            await new Promise(resolve => setTimeout(resolve, 150));
+
+            // Second execution after TTL
+            await registry.executeTool('test_tool', params);
+
+            expect(mockTool.execute).toHaveBeenCalledTimes(2);
+        });
+
+        it('should clean expired cache entries', async () => {
+            mockTool.metadata.caching!.ttl = 100;
+            registry.registerTool(mockTool);
+            const params = { test: 'value' };
+
+            // Execute and cache
+            await registry.executeTool('test_tool', params);
+
+            // Wait for cache to expire
+            await new Promise(resolve => setTimeout(resolve, 150));
+
+            // Clean cache
+            registry.cleanCache();
+
+            // Verify cache is cleaned by forcing a new execution
+            await registry.executeTool('test_tool', params);
+            expect(mockTool.execute).toHaveBeenCalledTimes(2);
+        });
+    });
+
+    describe('Category Management', () => {
+        it('should return empty array for unknown category', () => {
+            const tools = registry.getToolsByCategory('unknown' as ToolCategory);
+            expect(tools).toEqual([]);
+        });
+
+        it('should handle tools across multiple categories', () => {
+            const systemTool: EnhancedTool = {
+                ...mockTool,
+                name: 'system_tool',
+                metadata: {
+                    ...mockTool.metadata,
+                    category: ToolCategory.SYSTEM
+                }
+            };
+
+            const automationTool: EnhancedTool = {
+                ...mockTool,
+                name: 'automation_tool',
+                metadata: {
+                    ...mockTool.metadata,
+                    category: ToolCategory.AUTOMATION
+                }
+            };
+
+            registry.registerTool(mockTool); // DEVICE category
+            registry.registerTool(systemTool);
+            registry.registerTool(automationTool);
+
+            expect(registry.getToolsByCategory(ToolCategory.DEVICE)).toHaveLength(1);
+            expect(registry.getToolsByCategory(ToolCategory.SYSTEM)).toHaveLength(1);
+            expect(registry.getToolsByCategory(ToolCategory.AUTOMATION)).toHaveLength(1);
+        });
+    });
+}); 
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