diff --git a/src/__tests__/agent-as-tool.test.ts b/src/__tests__/agent-as-tool.test.ts
index 6402048..1427b85 100644
--- a/src/__tests__/agent-as-tool.test.ts
+++ b/src/__tests__/agent-as-tool.test.ts
@@ -7,7 +7,7 @@ import {
   generateTraceId,
   agentAsTool,
   getTextContent
-} from '../index';
+} from '../index.js';
 
 type Ctx = { userId: string; permissions: string[] };
 
diff --git a/src/__tests__/engine.test.ts b/src/__tests__/engine.test.ts
index d310fcf..f3409ae 100644
--- a/src/__tests__/engine.test.ts
+++ b/src/__tests__/engine.test.ts
@@ -1,4 +1,4 @@
-import { run, RunConfig, RunState, generateTraceId, generateRunId } from '../index';
+import { run, RunConfig, RunState, generateTraceId, generateRunId } from '../index.js';
 
 describe('JAF Engine', () => {
   const mockContext = { userId: 'test' };
diff --git a/src/__tests__/hitl.test.ts b/src/__tests__/hitl.test.ts
index 266c619..d17e012 100644
--- a/src/__tests__/hitl.test.ts
+++ b/src/__tests__/hitl.test.ts
@@ -1,5 +1,5 @@
 import { z } from 'zod';
-import { run, RunConfig, RunState, generateTraceId, generateRunId, Agent, Tool, getTextContent } from '../index';
+import { run, RunConfig, RunState, generateTraceId, generateRunId, Agent, Tool, getTextContent } from '../index.js';
 
 describe('HITL approvals', () => {
   const sensitiveTool: Tool<{ x: number }, any> = {
diff --git a/src/__tests__/validation.test.ts b/src/__tests__/validation.test.ts
index 3b2172f..ef11fbc 100644
--- a/src/__tests__/validation.test.ts
+++ b/src/__tests__/validation.test.ts
@@ -3,7 +3,7 @@ import {
   createPathValidator, 
   createContentFilter,
   createRateLimiter 
-} from '../policies/validation';
+} from '../policies/validation.js';
 
 describe('Validation Policies', () => {
   describe('composeValidations', () => {
diff --git a/src/a2a/__tests__/agent.test.ts b/src/a2a/__tests__/agent.test.ts
index 5311ace..fb6ba9b 100644
--- a/src/a2a/__tests__/agent.test.ts
+++ b/src/a2a/__tests__/agent.test.ts
@@ -19,7 +19,7 @@ import {
   type A2AToolResult,
   type ToolContext,
   StreamEvent,
-} from '../index';
+} from '../index.js';
 
 describe('A2A Agent', () => {
   describe('createA2ATool', () => {
diff --git a/src/a2a/__tests__/client.test.ts b/src/a2a/__tests__/client.test.ts
index e854d07..89474a5 100644
--- a/src/a2a/__tests__/client.test.ts
+++ b/src/a2a/__tests__/client.test.ts
@@ -8,7 +8,7 @@ import {
   createMessageRequest,
   createStreamingMessageRequest,
   extractTextResponse,
-} from '../index';
+} from '../index.js';
 
 // Mock fetch for testing
 const mockFetch = jest.fn();
diff --git a/src/a2a/__tests__/executor.test.ts b/src/a2a/__tests__/executor.test.ts
index d37d278..17771f1 100644
--- a/src/a2a/__tests__/executor.test.ts
+++ b/src/a2a/__tests__/executor.test.ts
@@ -12,7 +12,7 @@ import {
   createA2ATextMessage,
   type A2AExecutionContext,
   type A2AStreamEvent
-} from '../index';
+} from '../index.js';
 
 describe('A2A Executor', () => {
   // Mock model provider
diff --git a/src/a2a/__tests__/integration.test.ts b/src/a2a/__tests__/integration.test.ts
index 80baa65..fbb5154 100644
--- a/src/a2a/__tests__/integration.test.ts
+++ b/src/a2a/__tests__/integration.test.ts
@@ -19,7 +19,7 @@ import {
   type SendMessageRequest,
   type JSONRPCRequest,
   type A2ATaskProvider
-} from '../index';
+} from '../index.js';
 
 describe('A2A Integration', () => {
   // Mock model provider for integration tests
diff --git a/src/a2a/__tests__/protocol.test.ts b/src/a2a/__tests__/protocol.test.ts
index 60a012d..e1c9e08 100644
--- a/src/a2a/__tests__/protocol.test.ts
+++ b/src/a2a/__tests__/protocol.test.ts
@@ -18,7 +18,7 @@ import {
   type SendMessageRequest,
   type A2AAgent,
   type A2ATaskProvider
-} from '../index';
+} from '../index.js';
 
 describe('A2A Protocol', () => {
   // Mock agent for testing
diff --git a/src/a2a/__tests__/server.test.ts b/src/a2a/__tests__/server.test.ts
index 276d4f5..c0beda7 100644
--- a/src/a2a/__tests__/server.test.ts
+++ b/src/a2a/__tests__/server.test.ts
@@ -10,7 +10,7 @@ import {
   createA2ATool,
   generateAgentCard,
   type A2AServerConfig,
-} from '../index';
+} from '../index.js';
 
 describe('A2A Server', () => {
   // Test agents
diff --git a/src/a2a/__tests__/types.test.ts b/src/a2a/__tests__/types.test.ts
index 220a0e2..31a5a05 100644
--- a/src/a2a/__tests__/types.test.ts
+++ b/src/a2a/__tests__/types.test.ts
@@ -15,7 +15,7 @@ import {
   A2AErrorCodes,
   a2aMessageSchema,
   sendMessageRequestSchema
-} from '../types';
+} from '../types.js';
 
 describe('A2A Types', () => {
   describe('A2AMessage', () => {
diff --git a/src/a2a/index.ts b/src/a2a/index.ts
index 4b703da..8e15efb 100644
--- a/src/a2a/index.ts
+++ b/src/a2a/index.ts
@@ -115,9 +115,9 @@ export {
 } from './agent-card.js';
 
 // Server Functions
-import { 
-  createA2AServer, 
-  startA2AServer 
+import {
+  createA2AServer,
+  startA2AServer
 } from './server.js';
 export {
   createA2AServer,
diff --git a/src/adk/__tests__/agents.test.ts b/src/adk/__tests__/agents.test.ts
index 3377169..5f380e0 100644
--- a/src/adk/__tests__/agents.test.ts
+++ b/src/adk/__tests__/agents.test.ts
@@ -30,10 +30,10 @@ import {
   compareAgents,
   createAgentError,
   withAgentErrorHandling
-} from '../agents';
+} from '../agents/index.js';
 
-import { createFunctionTool } from '../tools';
-import { AgentConfig, Tool, Model } from '../types';
+import { createFunctionTool } from '../tools/index.js';
+import { AgentConfig, Tool, Model } from '../types.js';
 
 describe('Agent System', () => {
   const mockTool: Tool = createFunctionTool({
diff --git a/src/adk/__tests__/content.test.ts b/src/adk/__tests__/content.test.ts
index 0ecacf4..9ce2729 100644
--- a/src/adk/__tests__/content.test.ts
+++ b/src/adk/__tests__/content.test.ts
@@ -35,7 +35,7 @@ import {
   getLastModelMessage,
   getContentStats,
   getConversationStats
-} from '../content';
+} from '../content/index.js';
 
 describe('Content System', () => {
   describe('Content Creation', () => {
diff --git a/src/adk/__tests__/integration.test.ts b/src/adk/__tests__/integration.test.ts
index e7b63ac..73ee01e 100644
--- a/src/adk/__tests__/integration.test.ts
+++ b/src/adk/__tests__/integration.test.ts
@@ -27,9 +27,9 @@ import {
   Model,
   ToolParameterType,
   AgentEvent
-} from '../index';
+} from '../index.js';
 
-import { streamToArray } from '../streaming';
+import { streamToArray } from '../streaming/index.js';
 
 // Mock the Core ModelProvider to avoid real API calls in tests
 let mockCallCount = 0;
diff --git a/src/adk/__tests__/models.test.ts b/src/adk/__tests__/models.test.ts
index 155650f..2d8596a 100644
--- a/src/adk/__tests__/models.test.ts
+++ b/src/adk/__tests__/models.test.ts
@@ -11,7 +11,7 @@ import {
   CLAUDE_3_OPUS,
   CLAUDE_3_SONNET,
   CLAUDE_3_HAIKU
-} from '../models';
+} from '../models.js';
 
 describe('Model Enum', () => {
   it('should have all major model categories', () => {
diff --git a/src/adk/__tests__/runners.test.ts b/src/adk/__tests__/runners.test.ts
index 314c44c..89b5782 100644
--- a/src/adk/__tests__/runners.test.ts
+++ b/src/adk/__tests__/runners.test.ts
@@ -10,40 +10,40 @@ import {
   validateRunContext,
   getRunnerStats,
   withRunnerErrorHandling
-} from '../runners';
+} from '../runners/index.js';
 
 import {
   createAgent,
   createSimpleAgent,
   createMultiAgent
-} from '../agents';
+} from '../agents/index.js';
 
 import {
   createFunctionTool,
   createEchoTool,
   createCalculatorTool
-} from '../tools';
+} from '../tools/index.js';
 
-import { Model, ToolParameterType } from '../types';
+import { Model, ToolParameterType } from '../types.js';
 
 import {
   createInMemorySessionProvider,
   addMessageToSession
-} from '../sessions';
+} from '../sessions/index.js';
 
 import {
   createUserMessage,
   createModelMessage,
   getFunctionCalls
-} from '../content';
+} from '../content/index.js';
 
 import {
   createSchemaValidator,
   stringSchema,
   isString
-} from '../schemas';
+} from '../schemas/index.js';
 
-import { RunnerConfig, RunContext, AgentConfig, GuardrailFunction, AgentError } from '../types';
+import { RunnerConfig, RunContext, AgentConfig, GuardrailFunction, AgentError } from '../types.js';
 
 // Mock the LLM service to avoid real API calls
 let mockLLMResponses: any[] = [];
diff --git a/src/adk/__tests__/schemas.test.ts b/src/adk/__tests__/schemas.test.ts
index 851b3af..03a183c 100644
--- a/src/adk/__tests__/schemas.test.ts
+++ b/src/adk/__tests__/schemas.test.ts
@@ -37,9 +37,9 @@ import {
   weatherResponseValidator,
   createValidationError,
   withSchemaValidation
-} from '../schemas';
+} from '../schemas/index.js';
 
-import { JsonSchema, ValidationResult } from '../types';
+import { JsonSchema, ValidationResult } from '../types.js';
 
 describe('Schema Validation', () => {
   describe('Schema Validator Creation', () => {
diff --git a/src/adk/__tests__/sessions.test.ts b/src/adk/__tests__/sessions.test.ts
index cfad10f..f501338 100644
--- a/src/adk/__tests__/sessions.test.ts
+++ b/src/adk/__tests__/sessions.test.ts
@@ -28,10 +28,10 @@ import {
   createMemoryProviderBridge,
   createSessionError,
   withSessionErrorHandling
-} from '../sessions';
+} from '../sessions/index.js';
 
-import { createUserMessage, createModelMessage, createSystemMessage } from '../content';
-import { Session, SessionProvider } from '../types';
+import { createUserMessage, createModelMessage, createSystemMessage } from '../content/index.js';
+import { Session, SessionProvider } from '../types.js';
 
 describe('Session Management', () => {
   describe('Session Creation', () => {
diff --git a/src/adk/__tests__/streaming.test.ts b/src/adk/__tests__/streaming.test.ts
index d33e874..3cf827d 100644
--- a/src/adk/__tests__/streaming.test.ts
+++ b/src/adk/__tests__/streaming.test.ts
@@ -45,10 +45,10 @@ import {
   streamToArray,
   takeFromStream,
   skipFromStream
-} from '../streaming';
+} from '../streaming/index.js';
 
-import { createUserMessage, createFunctionCall, createFunctionResponse } from '../content';
-import { AgentEvent, AgentEventType } from '../types';
+import { createUserMessage, createFunctionCall, createFunctionResponse } from '../content/index.js';
+import { AgentEvent, AgentEventType } from '../types.js';
 
 describe('Streaming System', () => {
   describe('Live Request Queue', () => {
diff --git a/src/adk/__tests__/tools.test.ts b/src/adk/__tests__/tools.test.ts
index eb60157..5c7ddeb 100644
--- a/src/adk/__tests__/tools.test.ts
+++ b/src/adk/__tests__/tools.test.ts
@@ -22,12 +22,12 @@ import {
   createEchoTool,
   createCalculatorTool,
   createTimestampTool
-} from '../tools';
+} from '../tools/index.js';
 
-import { createAgent } from '../agents';
-import { createInMemorySessionProvider } from '../sessions';
-import { createUserMessage } from '../content';
-import { Tool, ToolContext, OpenAPISpec, Model, ToolParameterType } from '../types';
+import { createAgent } from '../agents/index.js';
+import { createInMemorySessionProvider } from '../sessions/index.js';
+import { createUserMessage } from '../content/index.js';
+import { Tool, ToolContext, OpenAPISpec, Model, ToolParameterType } from '../types.js';
 
 describe('Tool System', () => {
   const mockSession = {
diff --git a/src/adk/agents/index.ts b/src/adk/agents/index.ts
index e498adf..c24f46e 100644
--- a/src/adk/agents/index.ts
+++ b/src/adk/agents/index.ts
@@ -20,7 +20,7 @@ import {
   throwAgentError,
   createAgentError,
   Model
-} from '../types';
+} from '../types.js';
 
 // ========== ID Generation ==========
 
diff --git a/src/adk/artifacts/__tests__/artifacts.test.ts b/src/adk/artifacts/__tests__/artifacts.test.ts
index bba12be..2bb61b6 100644
--- a/src/adk/artifacts/__tests__/artifacts.test.ts
+++ b/src/adk/artifacts/__tests__/artifacts.test.ts
@@ -13,8 +13,8 @@ import {
   clearSessionArtifacts,
   listSessionArtifacts,
   type ArtifactStorage
-} from '../index';
-import { Session } from '../../types';
+} from '../index.js';
+import { Session } from '../../types.js';
 
 describe('Artifact Storage System', () => {
   const testSessionId = 'test-session-123';
diff --git a/src/adk/content/index.ts b/src/adk/content/index.ts
index 7f44f63..dd59ea5 100644
--- a/src/adk/content/index.ts
+++ b/src/adk/content/index.ts
@@ -4,7 +4,7 @@
  * Functional content and message handling utilities
  */
 
-import { Content, Part, FunctionCall, FunctionResponse } from '../types';
+import { Content, Part, FunctionCall, FunctionResponse } from '../types.js';
 
 // ========== Content Creation ==========
 
diff --git a/src/adk/examples/advanced-features.ts b/src/adk/examples/advanced-features.ts
index 1983095..2ad9d43 100644
--- a/src/adk/examples/advanced-features.ts
+++ b/src/adk/examples/advanced-features.ts
@@ -31,7 +31,7 @@ import {
   SessionProvider,
   Model,
   ToolParameterType
-} from '../index';
+} from '../index.js';
 
 // ========== Schema Validation Example ==========
 
diff --git a/src/adk/examples/basic-agent.ts b/src/adk/examples/basic-agent.ts
index a8e27d6..59e5d6c 100644
--- a/src/adk/examples/basic-agent.ts
+++ b/src/adk/examples/basic-agent.ts
@@ -15,7 +15,7 @@ import {
   quickSetup,
   Model,
   ToolParameterType
-} from '../index';
+} from '../index.js';
 
 // ========== Example 1: Simple Chat Agent ==========
 
diff --git a/src/adk/examples/multi-agent.ts b/src/adk/examples/multi-agent.ts
index 3134826..d921feb 100644
--- a/src/adk/examples/multi-agent.ts
+++ b/src/adk/examples/multi-agent.ts
@@ -15,7 +15,7 @@ import {
   AgentConfig,
   Model,
   ToolParameterType
-} from '../index';
+} from '../index.js';
 
 // ========== Specialized Agents ==========
 
diff --git a/src/adk/index.ts b/src/adk/index.ts
index 282102a..90fe078 100644
--- a/src/adk/index.ts
+++ b/src/adk/index.ts
@@ -5,7 +5,7 @@
  */
 
 // ========== Core Types ==========
-export * from './types';
+export * from './types.js';
 
 // ========== Model Definitions ==========
 export { 
@@ -18,7 +18,7 @@ export {
   CLAUDE_3_OPUS,
   CLAUDE_3_SONNET,
   CLAUDE_3_HAIKU
-} from './models';
+} from './models.js';
 
 // ========== Content System ==========
 export {
@@ -65,7 +65,7 @@ export {
   getLastModelMessage,
   getContentStats,
   getConversationStats
-} from './content';
+} from './content/index.js';
 
 // ========== Agent System ==========
 export {
@@ -109,7 +109,7 @@ export {
   // Error Handling
   createAgentError,
   withAgentErrorHandling
-} from './agents';
+} from './agents/index.js';
 
 // ========== Tool System ==========
 export {
@@ -141,7 +141,7 @@ export {
   createEchoTool,
   createCalculatorTool,
   createTimestampTool
-} from './tools';
+} from './tools/index.js';
 
 // ========== Session Management ==========
 export {
@@ -185,7 +185,7 @@ export {
   // Error Handling
   createSessionError,
   withSessionErrorHandling
-} from './sessions';
+} from './sessions/index.js';
 
 // ========== Artifact Storage ==========
 export {
@@ -207,7 +207,7 @@ export {
   deleteSessionArtifact,
   clearSessionArtifacts,
   listSessionArtifacts
-} from './artifacts';
+} from './artifacts/index.js';
 
 // ========== Runner System ==========
 export {
@@ -225,7 +225,7 @@ export {
   
   // Error Handling
   withRunnerErrorHandling
-} from './runners';
+} from './runners/index.js';
 
 // ========== LLM Provider System ==========
 export {
@@ -317,7 +317,7 @@ export {
   // Error Handling
   createValidationError,
   withSchemaValidation
-} from './schemas';
+} from './schemas/index.js';
 
 // ========== Streaming System ==========
 export {
@@ -385,7 +385,7 @@ export {
   streamToArray,
   takeFromStream,
   skipFromStream
-} from './streaming';
+} from './streaming/index.js';
 
 // ========== Convenience Functions ==========
 
@@ -397,8 +397,8 @@ import {
   runAgent,
   runAgentStream,
   createFunctionTool
-} from './index';
-import { Agent, Tool, RunnerConfig, SessionProvider, Model, ToolParameterType } from './types';
+} from './index.js';
+import { Agent, Tool, RunnerConfig, SessionProvider, Model, ToolParameterType } from './types.js';
 
 /**
  * Quick setup for a simple agent with in-memory session management
diff --git a/src/adk/runners/index.ts b/src/adk/runners/index.ts
index b250e28..d8b8b1f 100644
--- a/src/adk/runners/index.ts
+++ b/src/adk/runners/index.ts
@@ -28,7 +28,7 @@ import {
   throwAgentError,
   throwToolError,
   throwSessionError
-} from '../types';
+} from '../types.js';
 
 import {
   generateRunnerGraph,
@@ -36,11 +36,11 @@ import {
   generateToolGraph,
   GraphOptions,
   GraphResult
-} from '../../visualization/graphviz';
+} from '../../visualization/graphviz.js';
 
-import { getOrCreateSession, addMessageToSession, addArtifactToSession } from '../sessions';
-import { executeTool } from '../tools';
-import { createModelMessage, getFunctionCalls, createUserMessage } from '../content';
+import { getOrCreateSession, addMessageToSession, addArtifactToSession } from '../sessions/index.js';
+import { executeTool } from '../tools/index.js';
+import { createModelMessage, getFunctionCalls, createUserMessage } from '../content/index.js';
 import { createAdkLLMService } from '../providers/llm-service.js';
 import { createAdkLLMConfigFromEnvironment } from '../config/llm-config.js';
 import { safeConsole } from '../../utils/logger.js';
diff --git a/src/adk/schemas/index.ts b/src/adk/schemas/index.ts
index 6929dcf..b09479b 100644
--- a/src/adk/schemas/index.ts
+++ b/src/adk/schemas/index.ts
@@ -12,10 +12,10 @@ import {
   ValidationError,
   throwValidationError,
   createValidationError
-} from '../types';
+} from '../types.js';
 
 // Re-export createValidationError for external use
-export { createValidationError } from '../types';
+export { createValidationError } from '../types.js';
 
 // ========== Schema Validator Creation ==========
 
diff --git a/src/adk/sessions/index.ts b/src/adk/sessions/index.ts
index 50b48c1..21265f3 100644
--- a/src/adk/sessions/index.ts
+++ b/src/adk/sessions/index.ts
@@ -14,7 +14,7 @@ import {
   ValidationResult,
   throwSessionError,
   createSessionError
-} from '../types';
+} from '../types.js';
 import { safeConsole } from '../../utils/logger.js';
 
 // ========== Session Creation ==========
diff --git a/src/adk/streaming/index.ts b/src/adk/streaming/index.ts
index fdea123..7db5d77 100644
--- a/src/adk/streaming/index.ts
+++ b/src/adk/streaming/index.ts
@@ -13,7 +13,7 @@ import {
   ResponseModality,
   FunctionCall,
   FunctionResponse
-} from '../types';
+} from '../types.js';
 import { safeConsole } from '../../utils/logger.js';
 
 // ========== Live Request Queue ==========
diff --git a/src/adk/tools/index.ts b/src/adk/tools/index.ts
index 6336090..ae127f1 100644
--- a/src/adk/tools/index.ts
+++ b/src/adk/tools/index.ts
@@ -21,7 +21,7 @@ import {
   FunctionToolConfig,
   ToolSource,
   ToolParameterType
-} from '../types';
+} from '../types.js';
 
 // ========== Tool Creation ==========
 
diff --git a/src/core/state.ts b/src/core/state.ts
index f2f687f..45def27 100644
--- a/src/core/state.ts
+++ b/src/core/state.ts
@@ -1,4 +1,4 @@
-import { RunState, Interruption, RunConfig } from './types';
+import { RunState, Interruption, RunConfig } from './types.js';
 import { safeConsole } from '../utils/logger.js';
 
 export async function approve<Ctx>(
diff --git a/src/core/types.ts b/src/core/types.ts
index 34eccee..4fe35fc 100644
--- a/src/core/types.ts
+++ b/src/core/types.ts
@@ -1,6 +1,6 @@
 import { z } from 'zod';
-import { MemoryConfig } from '../memory/types';
-import type { ApprovalStorage } from '../memory/approval-storage';
+import { MemoryConfig } from '../memory/types.js';
+import type { ApprovalStorage } from '../memory/approval-storage.js';
 
 export type TraceId = string & { readonly _brand: 'TraceId' };
 export type RunId = string & { readonly _brand: 'RunId' };
diff --git a/src/index.ts b/src/index.ts
index 5c5d5b7..76b53c9 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,37 +1,37 @@
-export * from './core/types';
-export * from './core/engine';
-export * from './core/tracing';
-export * from './core/errors';
-export * from './core/tool-results';
-export * from './core/agent-as-tool';
+export * from './core/types.js';
+export * from './core/engine.js';
+export * from './core/tracing.js';
+export * from './core/errors.js';
+export * from './core/tool-results.js';
+export * from './core/agent-as-tool.js';
 
-export * from './providers/model';
-// export * from './providers/mcp'; // Commented out for test compatibility
+export * from './providers/model.js';
+// export * from './providers/mcp.js'; // Commented out for test compatibility
 
-export * from './policies/validation';
-export * from './policies/handoff';
+export * from './policies/validation.js';
+export * from './policies/handoff.js';
 
-export * from './server';
+export * from './server/index.js';
 
 // Built-in tools
-export * from './tools';
+export * from './tools/index.js';
 
 // Memory providers
-export * from './memory/types';
-export * from './memory/factory';
-export * from './memory/providers/in-memory';
-export * from './memory/providers/redis';
-export * from './memory/providers/postgres';
+export * from './memory/types.js';
+export * from './memory/factory.js';
+export * from './memory/providers/in-memory.js';
+export * from './memory/providers/redis.js';
+export * from './memory/providers/postgres.js';
 
 // A2A Protocol Support
-export * from './a2a';
+export * from './a2a/index.js';
 
 // ADK Layer - Functional Agent Development Kit
 // Re-export specific ADK modules to avoid conflicts
-export * as ADK from './adk';
+export * as ADK from './adk/index.js';
 
 import { v4 as uuidv4 } from 'uuid';
-import { TraceId, RunId, createTraceId, createRunId } from './core/types';
+import { TraceId, RunId, createTraceId, createRunId } from './core/types.js';
 
 export function generateTraceId(): TraceId {
   return createTraceId(uuidv4());
diff --git a/src/memory/approval-storage.ts b/src/memory/approval-storage.ts
index 68ef311..4d7b463 100644
--- a/src/memory/approval-storage.ts
+++ b/src/memory/approval-storage.ts
@@ -1,5 +1,5 @@
-import { RunId, TraceId, ApprovalValue } from '../core/types';
-import { Result, createSuccess, createFailure, createMemoryStorageError } from './types';
+import { RunId, TraceId, ApprovalValue } from '../core/types.js';
+import { Result, createSuccess, createFailure, createMemoryStorageError } from './types.js';
 
 /**
  * Approval storage interface for managing tool approval states
diff --git a/src/memory/factory.ts b/src/memory/factory.ts
index ab7c56d..44435e3 100644
--- a/src/memory/factory.ts
+++ b/src/memory/factory.ts
@@ -5,10 +5,10 @@ import {
   RedisConfig, 
   PostgresConfig,
   createMemoryConnectionError
-} from './types';
-import { createInMemoryProvider } from './providers/in-memory';
-import { createRedisProvider } from './providers/redis';
-import { createPostgresProvider } from './providers/postgres';
+} from './types.js';
+import { createInMemoryProvider } from './providers/in-memory.js';
+import { createRedisProvider } from './providers/redis.js';
+import { createPostgresProvider } from './providers/postgres.js';
 
 /**
  * Create a memory provider from configuration
diff --git a/src/memory/providers/in-memory.ts b/src/memory/providers/in-memory.ts
index f9f8a77..8e4a72b 100644
--- a/src/memory/providers/in-memory.ts
+++ b/src/memory/providers/in-memory.ts
@@ -1,4 +1,4 @@
-import { Message, TraceId } from '../../core/types';
+import { Message, TraceId } from '../../core/types.js';
 import {
   MemoryProvider,
   ConversationMemory,
@@ -9,7 +9,7 @@ import {
   createFailure,
   createMemoryNotFoundError,
   createMemoryStorageError
-} from '../types';
+} from '../types.js';
 import { safeConsole } from '../../utils/logger.js';
 
 /**
diff --git a/src/memory/providers/postgres.ts b/src/memory/providers/postgres.ts
index f4306bb..cc82adc 100644
--- a/src/memory/providers/postgres.ts
+++ b/src/memory/providers/postgres.ts
@@ -1,4 +1,4 @@
-import { Message, TraceId } from '../../core/types';
+import { Message, TraceId } from '../../core/types.js';
 import {
   MemoryProvider,
   ConversationMemory,
@@ -11,7 +11,7 @@ import {
   createMemoryNotFoundError,
   createMemoryStorageError,
   ConversationStatus
-} from '../types';
+} from '../types.js';
 import { safeConsole } from '../../utils/logger.js';
 
 // PostgreSQL client interface - compatible with pg, postgres.js, etc.
diff --git a/src/memory/providers/redis.ts b/src/memory/providers/redis.ts
index e78abe1..b61cf01 100644
--- a/src/memory/providers/redis.ts
+++ b/src/memory/providers/redis.ts
@@ -1,4 +1,4 @@
-import { Message, TraceId } from '../../core/types';
+import { Message, TraceId } from '../../core/types.js';
 import {
   MemoryProvider,
   ConversationMemory,
@@ -10,7 +10,7 @@ import {
   createMemoryConnectionError,
   createMemoryNotFoundError,
   createMemoryStorageError
-} from '../types';
+} from '../types.js';
 import { safeConsole } from '../../utils/logger.js';
 
 // Redis client interface - compatible with ioredis, node-redis, etc.
diff --git a/src/memory/types.ts b/src/memory/types.ts
index 145e5c9..2680759 100644
--- a/src/memory/types.ts
+++ b/src/memory/types.ts
@@ -1,5 +1,5 @@
 import { z } from 'zod';
-import { Message, TraceId, RunId } from '../core/types';
+import { Message, TraceId, RunId } from '../core/types.js';
 
 // Conversation status types
 export type ConversationStatus = 
diff --git a/src/providers/index.ts b/src/providers/index.ts
index 3c52c0f..3a29be9 100644
--- a/src/providers/index.ts
+++ b/src/providers/index.ts
@@ -1,8 +1,8 @@
 // Public provider entrypoint: re-export provider modules
 // This backs the `@xynehq/jaf/providers` subpath export declared in package.json
 
-export * from './model';
-export * from './mcp';
+export * from './model.js';
+export * from './mcp.js';
 export {
   createAiSdkProvider,
   type AiSdkFunctionTool,
@@ -10,5 +10,5 @@ export {
   type AiSdkChatRequest,
   type AiSdkChatResponse,
   type AiSdkClient,
-} from './ai-sdk';
+} from './ai-sdk.js';
 
diff --git a/src/server/index.ts b/src/server/index.ts
index f6d1e8a..ffb8100 100644
--- a/src/server/index.ts
+++ b/src/server/index.ts
@@ -1,6 +1,6 @@
-import { createJAFServer } from './server';
-import { ServerConfig } from './types';
-import { Agent, RunConfig } from '../core/types';
+import { createJAFServer } from './server.js';
+import { ServerConfig } from './types.js';
+import { Agent, RunConfig } from '../core/types.js';
 
 /**
  * Start a development server for testing agents locally (functional approach)
@@ -75,12 +75,12 @@ export async function runServer<Ctx>(
 }
 
 
-export { createJAFServer } from './server';
+export { createJAFServer } from './server.js';
 // runServer is exported above
-export type { 
-  ServerConfig, 
-  ChatRequest, 
-  ChatResponse, 
-  AgentListResponse, 
-  HealthResponse 
-} from './types';
\ No newline at end of file
+export type {
+  ServerConfig,
+  ChatRequest,
+  ChatResponse,
+  AgentListResponse,
+  HealthResponse
+} from './types.js';
\ No newline at end of file
diff --git a/src/server/types.ts b/src/server/types.ts
index 6113450..6552f6a 100644
--- a/src/server/types.ts
+++ b/src/server/types.ts
@@ -1,6 +1,6 @@
 import { z } from 'zod';
-import { Agent, RunConfig } from '../core/types';
-import { MemoryProvider } from '../memory/types';
+import { Agent, RunConfig } from '../core/types.js';
+import { MemoryProvider } from '../memory/types.js';
 
 export interface ServerConfig<Ctx> {
   port?: number;
diff --git a/src/tools/index.ts b/src/tools/index.ts
index 3531606..efc760c 100644
--- a/src/tools/index.ts
+++ b/src/tools/index.ts
@@ -1 +1 @@
-export * from './math';
+export * from './math.js';
diff --git a/src/tools/math.ts b/src/tools/math.ts
index d61b8e4..6f2f343 100644
--- a/src/tools/math.ts
+++ b/src/tools/math.ts
@@ -1,7 +1,7 @@
 import { z } from 'zod';
-import { Tool } from '../core/types';
-import { withErrorHandling } from '../core/tool-results';
-import { evaluateMathExpression, safeMath } from '../utils/safe-math';
+import { Tool } from '../core/types.js';
+import { withErrorHandling } from '../core/tool-results.js';
+import { evaluateMathExpression, safeMath } from '../utils/safe-math.js';
 
 // NOTE: Use an OBJECT schema (no unions) so providers like Gemini accept it.
 const MathArgsSchema = z.object({
diff --git a/src/utils/index.ts b/src/utils/index.ts
index bf834d9..70bbae0 100644
--- a/src/utils/index.ts
+++ b/src/utils/index.ts
@@ -2,6 +2,6 @@
  * Utils module exports
  */
 
-export * from './safe-math';
-export * from './logger';
-export * from './attachments';
+export * from './safe-math.js';
+export * from './logger.js';
+export * from './attachments.js';
diff --git a/src/visualization/example.ts b/src/visualization/example.ts
index 044c55e..c4419e7 100644
--- a/src/visualization/example.ts
+++ b/src/visualization/example.ts
@@ -4,14 +4,14 @@
  * Example demonstrating how to use the Graphviz visualization functionality
  */
 
-import { Agent, Tool, RunnerConfig } from '../adk/types';
-import { createRunnerConfig } from '../adk/runners';
-import { createInMemorySessionProvider } from '../adk/sessions';
-import { 
-  generateAgentVisualization, 
-  generateToolVisualization, 
-  generateRunnerGraphPng 
-} from '../adk/runners';
+import { Agent, Tool, RunnerConfig } from '../adk/types.js';
+import { createRunnerConfig } from '../adk/runners/index.js';
+import { createInMemorySessionProvider } from '../adk/sessions/index.js';
+import {
+  generateAgentVisualization,
+  generateToolVisualization,
+  generateRunnerGraphPng
+} from '../adk/runners/index.js';
 
 // ========== Example Agent and Tools ==========
 
diff --git a/src/visualization/graphviz.ts b/src/visualization/graphviz.ts
index c0d172d..fcfe6e5 100644
--- a/src/visualization/graphviz.ts
+++ b/src/visualization/graphviz.ts
@@ -4,7 +4,7 @@
  * Functional visualization system for agents and tools using Graphviz
  */
 
-import { Agent, Tool, RunnerConfig } from '../adk/types';
+import { Agent, Tool, RunnerConfig } from '../adk/types.js';
 import { writeFileSync } from 'fs';
 import { execSync } from 'child_process';
 
diff --git a/src/visualization/index.ts b/src/visualization/index.ts
index 445e171..8898d99 100644
--- a/src/visualization/index.ts
+++ b/src/visualization/index.ts
@@ -11,7 +11,7 @@ export {
   generateRunnerGraph,
   getGraphDot,
   validateGraphOptions
-} from './graphviz';
+} from './graphviz.js';
 
 // Types
 export type {
@@ -19,7 +19,7 @@ export type {
   GraphResult,
   NodeStyle,
   EdgeStyle
-} from './graphviz';
+} from './graphviz.js';
 
 // Runner integration (re-export for convenience)
 export {
@@ -27,10 +27,10 @@ export {
   generateAgentVisualization,
   generateToolVisualization,
   generateRunnerGraphPng
-} from '../adk/runners';
+} from '../adk/runners/index.js';
 
 // Examples and utilities
 export {
   runVisualizationExamples,
   quickStartVisualization
-} from './example';
\ No newline at end of file
+} from './example.js';
\ No newline at end of file