diff --git a/README.md b/README.md
index 1c70c31..04b97ef 100644
--- a/README.md
+++ b/README.md
@@ -5,13 +5,17 @@
 The SDK interface to [Letta Code](https://github.com/letta-ai/letta-code). Build agents with persistent memory that learn over time.
 
 ```typescript
-import { prompt } from '@letta-ai/letta-code-sdk';
+import { createAgent, resumeSession } from '@letta-ai/letta-code-sdk';
 
-const result = await prompt('Find and fix the bug in auth.py', {
-  allowedTools: ['Read', 'Edit', 'Bash'],
-  permissionMode: 'bypassPermissions'
-});
-console.log(result.result);
+// Create an agent (has default conversation)
+const agentId = await createAgent();
+
+// Resume default conversation
+const session = resumeSession(agentId);
+await session.send('Find and fix the bug in auth.py');
+for await (const msg of session.stream()) {
+  if (msg.type === 'assistant') console.log(msg.content);
+}
 ```
 
 ## Installation
@@ -27,19 +31,24 @@ npm install @letta-ai/letta-code-sdk
 ```typescript
 import { prompt } from '@letta-ai/letta-code-sdk';
 
-const result = await prompt('Run: echo hello', {
-  allowedTools: ['Bash'],
-  permissionMode: 'bypassPermissions'
-});
-console.log(result.result); // "hello"
+// One-shot (uses default agent - like `letta -p`)
+const result = await prompt('What is 2 + 2?');
+console.log(result.result);
+
+// One-shot with specific agent
+const result2 = await prompt('Run: echo hello', agentId);
 ```
 
 ### Multi-turn session
 
 ```typescript
-import { createSession } from '@letta-ai/letta-code-sdk';
+import { createAgent, resumeSession } from '@letta-ai/letta-code-sdk';
 
-await using session = createSession();
+// Create an agent (has default conversation)
+const agentId = await createAgent();
+
+// Resume the default conversation
+await using session = resumeSession(agentId);
 
 await session.send('What is 5 + 3?');
 for await (const msg of session.stream()) {
@@ -57,16 +66,16 @@ for await (const msg of session.stream()) {
 Agents persist across sessions and remember context:
 
 ```typescript
-import { createSession, resumeSession } from '@letta-ai/letta-code-sdk';
+import { createAgent, resumeSession } from '@letta-ai/letta-code-sdk';
 
-// First session
-const session1 = createSession();
+// Create agent and teach it something
+const agentId = await createAgent();
+const session1 = resumeSession(agentId);
 await session1.send('Remember: the secret word is "banana"');
 for await (const msg of session1.stream()) { /* ... */ }
-const agentId = session1.agentId;
 session1.close();
 
-// Later...
+// Later... resume the default conversation
 await using session2 = resumeSession(agentId);
 await session2.send('What is the secret word?');
 for await (const msg of session2.stream()) {
@@ -79,44 +88,41 @@ for await (const msg of session2.stream()) {
 Run multiple concurrent conversations with the same agent. Each conversation has its own message history while sharing the agent's persistent memory.
 
 ```typescript
-import { createSession, resumeSession, resumeConversation } from '@letta-ai/letta-code-sdk';
+import { createAgent, createSession, resumeSession } from '@letta-ai/letta-code-sdk';
 
-// Create an agent
-const session = createSession();
-await session.send('Hello!');
-for await (const msg of session.stream()) { /* ... */ }
-const agentId = session.agentId;
-const conversationId = session.conversationId; // Save this!
-session.close();
+// Create an agent (has default conversation)
+const agentId = await createAgent();
 
-// Resume a specific conversation
-await using session2 = resumeConversation(conversationId);
+// Resume the default conversation
+const session1 = resumeSession(agentId);
+await session1.send('Hello!');
+for await (const msg of session1.stream()) { /* ... */ }
+const conversationId = session1.conversationId; // Save this!
+session1.close();
+
+// Resume a specific conversation by ID
+await using session2 = resumeSession(conversationId);  // auto-detects conv-xxx
 await session2.send('Continue our discussion...');
 for await (const msg of session2.stream()) { /* ... */ }
 
 // Create a NEW conversation on the same agent
-await using session3 = resumeSession(agentId, { newConversation: true });
+await using session3 = createSession(agentId);
 await session3.send('Start a fresh thread...');
 // session3.conversationId is different from conversationId
 
-// Resume with agent's default conversation
-await using session4 = resumeSession(agentId, { defaultConversation: true });
-
-// Resume last used session (agent + conversation)
-await using session5 = createSession({ continue: true });
-
-// Create new agent with a new (non-default) conversation
-await using session6 = createSession({ newConversation: true });
+// Create new agent + new conversation
+await using session4 = createSession();
 ```
 
 **Key concepts:**
 - **Agent** (`agentId`): Persistent entity with memory that survives across sessions
 - **Conversation** (`conversationId`): A message thread within an agent
-- **Session** (`sessionId`): A single execution/connection
+- **Session**: A single execution/connection
+- **Default conversation**: Always exists after `createAgent()` - use `resumeSession(agentId)` to access it
 
 Agents remember across conversations (via memory blocks), but each conversation has its own message history.
 
-## Agent Configuration
+## Session Configuration
 
 ### System Prompt
 
@@ -124,12 +130,12 @@ Choose from built-in presets or provide a custom prompt:
 
 ```typescript
 // Use a preset
-createSession({
+createSession(agentId, {
   systemPrompt: { type: 'preset', preset: 'letta-claude' }
 });
 
 // Use a preset with additional instructions
-createSession({
+createSession(agentId, {
   systemPrompt: { 
     type: 'preset', 
     preset: 'letta-claude',
@@ -138,7 +144,7 @@ createSession({
 });
 
 // Use a completely custom prompt
-createSession({
+createSession(agentId, {
   systemPrompt: 'You are a helpful Python expert.'
 });
 ```
@@ -153,35 +159,27 @@ createSession({
 
 ### Memory Blocks
 
-Configure which memory blocks the agent uses:
+Configure which memory blocks the session uses:
 
 ```typescript
 // Use default blocks (persona, human, project)
-createSession({});
+createSession(agentId);
 
 // Use specific preset blocks
-createSession({
+createSession(agentId, {
   memory: ['project', 'persona']  // Only these blocks
 });
 
 // Use custom blocks
-createSession({
+createSession(agentId, {
   memory: [
     { label: 'context', value: 'API documentation for Acme Corp...' },
     { label: 'rules', value: 'Always use TypeScript. Prefer functional patterns.' }
   ]
 });
 
-// Mix presets and custom blocks
-createSession({
-  memory: [
-    'project',  // Use default project block
-    { label: 'custom', value: 'Additional context...' }
-  ]
-});
-
 // No optional blocks (only core skills blocks)
-createSession({
+createSession(agentId, {
   memory: []
 });
 ```
@@ -191,18 +189,11 @@ createSession({
 Quickly customize common memory blocks:
 
 ```typescript
-createSession({
+createSession(agentId, {
   persona: 'You are a senior Python developer who writes clean, tested code.',
   human: 'Name: Alice. Prefers concise responses.',
   project: 'FastAPI backend for a todo app using PostgreSQL.'
 });
-
-// Combine with memory config
-createSession({
-  memory: ['persona', 'project'],  // Only include these blocks
-  persona: 'You are a Go expert.',
-  project: 'CLI tool for managing Docker containers.'
-});
 ```
 
 ### Tool Execution
@@ -210,20 +201,17 @@ createSession({
 Execute tools with automatic permission handling:
 
 ```typescript
-import { prompt } from '@letta-ai/letta-code-sdk';
+import { createAgent, createSession } from '@letta-ai/letta-code-sdk';
 
-// Run shell commands
-const result = await prompt('List all TypeScript files', {
+// Create agent and run commands
+const agentId = await createAgent();
+const session = createSession(agentId, {
   allowedTools: ['Glob', 'Bash'],
   permissionMode: 'bypassPermissions',
   cwd: '/path/to/project'
 });
-
-// Read and analyze code
-const analysis = await prompt('Explain what auth.ts does', {
-  allowedTools: ['Read', 'Grep'],
-  permissionMode: 'bypassPermissions'
-});
+await session.send('List all TypeScript files');
+for await (const msg of session.stream()) { /* ... */ }
 ```
 
 ## API Reference
@@ -232,10 +220,11 @@ const analysis = await prompt('Explain what auth.ts does', {
 
 | Function | Description |
 |----------|-------------|
-| `prompt(message, options?)` | One-shot query, returns result directly |
-| `createSession(options?)` | Create new agent session |
-| `resumeSession(agentId, options?)` | Resume existing agent by ID |
-| `resumeConversation(conversationId, options?)` | Resume specific conversation (derives agent automatically) |
+| `createAgent()` | Create new agent with default conversation, returns `agentId` |
+| `createSession(agentId?, options?)` | Create new conversation (on existing agent if provided, or new agent) |
+| `resumeSession(id, options?)` | Resume session - pass `agent-xxx` for default conv, `conv-xxx` for specific conv |
+| `prompt(message)` | One-shot query with default agent (like `letta -p`) |
+| `prompt(message, agentId)` | One-shot query with specific agent |
 
 ### Session
 
@@ -252,36 +241,19 @@ const analysis = await prompt('Explain what auth.ts does', {
 
 ```typescript
 interface SessionOptions {
-  // Model selection
   model?: string;
-
-  // Conversation options
-  conversationId?: string;      // Resume specific conversation
-  newConversation?: boolean;    // Create new conversation on agent
-  continue?: boolean;           // Resume last session (agent + conversation)
-  defaultConversation?: boolean; // Use agent's default conversation
-
-  // System prompt: string or preset config
-  systemPrompt?: string | {
-    type: 'preset';
-    preset: 'default' | 'letta-claude' | 'letta-codex' | 'letta-gemini' | 'claude' | 'codex' | 'gemini';
-    append?: string;
-  };
-
-  // Memory blocks: preset names, custom blocks, or mixed
+  systemPrompt?: string | { type: 'preset'; preset: string; append?: string };
   memory?: Array<string | CreateBlock | { blockId: string }>;
-
-  // Convenience: set block values directly
   persona?: string;
   human?: string;
   project?: string;
+  cwd?: string;
 
   // Tool configuration
   allowedTools?: string[];
   permissionMode?: 'default' | 'acceptEdits' | 'bypassPermissions';
-
-  // Working directory
-  cwd?: string;
+  canUseTool?: (toolName: string, toolInput: object) => Promise<CanUseToolResponse>;
+  maxTurns?: number;
 }
 ```
 
@@ -313,7 +285,7 @@ See [`examples/`](./examples/) for comprehensive examples including:
 - Basic session usage
 - Multi-turn conversations
 - Session resume with persistent memory
-- **Multi-threaded conversations** (resumeConversation, newConversation)
+- **Multi-threaded conversations** (createSession, resumeSession)
 - System prompt configuration
 - Memory block customization
 - Tool execution (Bash, Glob, Read, etc.)
diff --git a/examples/v2-examples.ts b/examples/v2-examples.ts
index 3048996..772c4c5 100644
--- a/examples/v2-examples.ts
+++ b/examples/v2-examples.ts
@@ -8,7 +8,7 @@
  * Run with: bun examples/v2-examples.ts [example]
  */
 
-import { createSession, resumeSession, resumeConversation, prompt } from '../src/index.js';
+import { createAgent, createSession, resumeSession, prompt } from '../src/index.js';
 
 async function main() {
   const example = process.argv[2] || 'basic';
@@ -82,8 +82,9 @@ async function main() {
 async function basicSession() {
   console.log('=== Basic Session ===\n');
 
-  await using session = createSession({
-    model: 'haiku',
+  // Create agent, then resume default conversation
+  const agentId = await createAgent();
+  await using session = resumeSession(agentId, {
     permissionMode: 'bypassPermissions',
   });
   
@@ -106,7 +107,8 @@ async function basicSession() {
 async function multiTurn() {
   console.log('=== Multi-Turn Conversation ===\n');
 
-  await using session = createSession({
+  // Create new agent + new conversation
+  await using session = createSession(undefined, {
     model: 'haiku',
     permissionMode: 'bypassPermissions',
   });
@@ -133,10 +135,8 @@ async function multiTurn() {
 async function oneShot() {
   console.log('=== One-Shot Prompt ===\n');
 
-  const result = await prompt('What is the capital of France? One word.', {
-    model: 'haiku',
-    permissionMode: 'bypassPermissions',
-  });
+  // One-shot creates new agent
+  const result = await prompt('What is the capital of France? One word.');
 
   if (result.success) {
     console.log(`Answer: ${result.result}`);
@@ -151,12 +151,13 @@ async function oneShot() {
 async function sessionResume() {
   console.log('=== Session Resume (Persistent Memory) ===\n');
 
-  let agentId: string | null = null;
+  // Create agent first
+  const agentId = await createAgent();
+  console.log(`[Setup] Created agent: ${agentId}\n`);
 
   // First session - establish a memory
   {
-    const session = createSession({
-      model: 'haiku',
+    const session = resumeSession(agentId, {
       permissionMode: 'bypassPermissions',
     });
     
@@ -171,8 +172,7 @@ async function sessionResume() {
       }
     }
     
-    agentId = session.agentId;
-    console.log(`[Session 1] Agent ID: ${agentId}\n`);
+    console.log(`[Session 1] Agent ID: ${session.agentId}\n`);
     session.close();
   }
 
@@ -180,7 +180,7 @@ async function sessionResume() {
 
   // Resume and verify agent remembers
   {
-    await using session = resumeSession(agentId!, {
+    await using session = resumeSession(agentId, {
       permissionMode: 'bypassPermissions',
     });
     
@@ -205,53 +205,71 @@ async function sessionResume() {
 async function testOptions() {
   console.log('=== Testing Options ===\n');
 
-  // Test model option
-  console.log('Testing model option...');
-  const modelResult = await prompt('Say "model test ok"', {
-    model: 'haiku',
-    permissionMode: 'bypassPermissions',
-  });
-  console.log(`  model: ${modelResult.success ? 'PASS' : 'FAIL'} - ${modelResult.result?.slice(0, 50)}`);
+  // Test basic session
+  console.log('Testing basic session...');
+  const agentId = await createAgent();
+  const modelResult = await prompt('Say "model test ok"', agentId);
+  console.log(`  basic: ${modelResult.success ? 'PASS' : 'FAIL'} - ${modelResult.result?.slice(0, 50)}`);
 
-  // Test systemPrompt option
+  // Test systemPrompt option via createSession
   console.log('Testing systemPrompt option...');
-  const sysPromptResult = await prompt('Tell me a fun fact about penguins in one sentence.', {
-    model: 'haiku',
+  const sysPromptSession = createSession(undefined, {
     systemPrompt: 'You love penguins and always try to work penguin facts into conversations.',
     permissionMode: 'bypassPermissions',
   });
-  const hasPenguin = sysPromptResult.result?.toLowerCase().includes('penguin');
-  console.log(`  systemPrompt: ${hasPenguin ? 'PASS' : 'PARTIAL'} - ${sysPromptResult.result?.slice(0, 80)}`);
+  await sysPromptSession.send('Tell me a fun fact about penguins in one sentence.');
+  let sysPromptResponse = '';
+  for await (const msg of sysPromptSession.stream()) {
+    if (msg.type === 'result') sysPromptResponse = msg.result || '';
+  }
+  sysPromptSession.close();
+  const hasPenguin = sysPromptResponse.toLowerCase().includes('penguin');
+  console.log(`  systemPrompt: ${hasPenguin ? 'PASS' : 'PARTIAL'} - ${sysPromptResponse.slice(0, 80)}`);
 
-  // Test cwd option
+  // Test cwd option via createSession
   console.log('Testing cwd option...');
-  const cwdResult = await prompt('Run pwd to show current directory', {
-    model: 'haiku',
+  const cwdSession = createSession(undefined, {
     cwd: '/tmp',
     allowedTools: ['Bash'],
     permissionMode: 'bypassPermissions',
   });
-  const hasTmp = cwdResult.result?.includes('/tmp');
-  console.log(`  cwd: ${hasTmp ? 'PASS' : 'CHECK'} - ${cwdResult.result?.slice(0, 60)}`);
+  await cwdSession.send('Run pwd to show current directory');
+  let cwdResponse = '';
+  for await (const msg of cwdSession.stream()) {
+    if (msg.type === 'result') cwdResponse = msg.result || '';
+  }
+  cwdSession.close();
+  const hasTmp = cwdResponse.includes('/tmp');
+  console.log(`  cwd: ${hasTmp ? 'PASS' : 'CHECK'} - ${cwdResponse.slice(0, 60)}`);
 
   // Test allowedTools option with tool execution
   console.log('Testing allowedTools option...');
-  const toolsResult = await prompt('Run: echo tool-test-ok', {
-    model: 'haiku',
+  const toolsSession = createSession(undefined, {
     allowedTools: ['Bash'],
     permissionMode: 'bypassPermissions',
   });
-  const hasToolOutput = toolsResult.result?.includes('tool-test-ok');
-  console.log(`  allowedTools: ${hasToolOutput ? 'PASS' : 'CHECK'} - ${toolsResult.result?.slice(0, 60)}`);
+  await toolsSession.send('Run: echo tool-test-ok');
+  let toolsResponse = '';
+  for await (const msg of toolsSession.stream()) {
+    if (msg.type === 'result') toolsResponse = msg.result || '';
+  }
+  toolsSession.close();
+  const hasToolOutput = toolsResponse.includes('tool-test-ok');
+  console.log(`  allowedTools: ${hasToolOutput ? 'PASS' : 'CHECK'} - ${toolsResponse.slice(0, 60)}`);
 
   // Test permissionMode: bypassPermissions
   console.log('Testing permissionMode: bypassPermissions...');
-  const bypassResult = await prompt('Run: echo bypass-test', {
-    model: 'haiku',
+  const bypassSession = createSession(undefined, {
     allowedTools: ['Bash'],
     permissionMode: 'bypassPermissions',
   });
-  const hasBypassOutput = bypassResult.result?.includes('bypass-test');
+  await bypassSession.send('Run: echo bypass-test');
+  let bypassResponse = '';
+  for await (const msg of bypassSession.stream()) {
+    if (msg.type === 'result') bypassResponse = msg.result || '';
+  }
+  bypassSession.close();
+  const hasBypassOutput = bypassResponse.includes('bypass-test');
   console.log(`  permissionMode: ${hasBypassOutput ? 'PASS' : 'CHECK'}`);
 
   console.log();
@@ -264,8 +282,8 @@ async function testOptions() {
 async function testMessageTypes() {
   console.log('=== Testing Message Types ===\n');
 
-  const session = createSession({
-    model: 'haiku',
+  const agentId = await createAgent();
+  const session = resumeSession(agentId, {
     permissionMode: 'bypassPermissions',
   });
 
@@ -309,7 +327,8 @@ async function testMessageTypes() {
 async function testSessionProperties() {
   console.log('=== Testing Session Properties ===\n');
 
-  const session = createSession({
+  // Create new agent + new conversation
+  const session = createSession(undefined, {
     model: 'haiku',
     permissionMode: 'bypassPermissions',
   });
@@ -343,44 +362,45 @@ async function testSessionProperties() {
 async function testToolExecution() {
   console.log('=== Testing Tool Execution ===\n');
 
+  // Create a shared agent for tool tests
+  const agentId = await createAgent();
+  
+  async function runWithTools(message: string, tools: string[]): Promise<string> {
+    const session = createSession(agentId, {
+      allowedTools: tools,
+      permissionMode: 'bypassPermissions',
+    });
+    await session.send(message);
+    let result = '';
+    for await (const msg of session.stream()) {
+      if (msg.type === 'result') result = msg.result || '';
+    }
+    session.close();
+    return result;
+  }
+
   // Test 1: Basic command execution
   console.log('Testing basic command execution...');
-  const echoResult = await prompt('Run: echo hello-world', {
-    model: 'haiku',
-    allowedTools: ['Bash'],
-    permissionMode: 'bypassPermissions',
-  });
-  const hasHello = echoResult.result?.includes('hello-world');
+  const echoResult = await runWithTools('Run: echo hello-world', ['Bash']);
+  const hasHello = echoResult.includes('hello-world');
   console.log(`  echo command: ${hasHello ? 'PASS' : 'FAIL'}`);
 
   // Test 2: Command with arguments
   console.log('Testing command with arguments...');
-  const argsResult = await prompt('Run: echo "arg1 arg2 arg3"', {
-    model: 'haiku',
-    allowedTools: ['Bash'],
-    permissionMode: 'bypassPermissions',
-  });
-  const hasArgs = argsResult.result?.includes('arg1') && argsResult.result?.includes('arg3');
+  const argsResult = await runWithTools('Run: echo "arg1 arg2 arg3"', ['Bash']);
+  const hasArgs = argsResult.includes('arg1') && argsResult.includes('arg3');
   console.log(`  echo with args: ${hasArgs ? 'PASS' : 'FAIL'}`);
 
   // Test 3: File reading with Glob
   console.log('Testing Glob tool...');
-  const globResult = await prompt('List all .ts files in the current directory using Glob', {
-    model: 'haiku',
-    allowedTools: ['Glob'],
-    permissionMode: 'bypassPermissions',
-  });
-  console.log(`  Glob tool: ${globResult.success ? 'PASS' : 'FAIL'}`);
+  const globResult = await runWithTools('List all .ts files in the current directory using Glob', ['Glob']);
+  console.log(`  Glob tool: ${globResult ? 'PASS' : 'FAIL'}`);
 
   // Test 4: Multi-step tool usage (agent decides which tools to use)
   console.log('Testing multi-step tool usage...');
-  const multiResult = await prompt('First run "echo step1", then run "echo step2". Show me both outputs.', {
-    model: 'haiku',
-    allowedTools: ['Bash'],
-    permissionMode: 'bypassPermissions',
-  });
-  const hasStep1 = multiResult.result?.includes('step1');
-  const hasStep2 = multiResult.result?.includes('step2');
+  const multiResult = await runWithTools('First run "echo step1", then run "echo step2". Show me both outputs.', ['Bash']);
+  const hasStep1 = multiResult.includes('step1');
+  const hasStep2 = multiResult.includes('step2');
   console.log(`  multi-step: ${hasStep1 && hasStep2 ? 'PASS' : 'PARTIAL'} (step1: ${hasStep1}, step2: ${hasStep2})`);
 
   console.log();
@@ -398,37 +418,47 @@ async function testPermissionCallback() {
 
   // Test 1: Allow specific commands via callback
   console.log('Testing canUseTool callback (allow)...');
-  const allowResult = await prompt('Run: echo callback-allowed', {
-    model: 'haiku',
+  const allowSession = createSession(undefined, {
     // NO allowedTools - this ensures callback is invoked
     permissionMode: 'default',
     canUseTool: async (toolName, toolInput) => {
       console.error('CALLBACK:', toolName, toolInput);
       const command = (toolInput as { command?: string }).command || '';
       if (command.includes('callback-allowed')) {
-        return { allow: true, reason: 'Command whitelisted' };
+        return { behavior: 'allow', updatedInput: null };
       }
-      return { allow: false, reason: 'Command not whitelisted' };
+      return { behavior: 'deny', message: 'Command not whitelisted' };
     },
   });
-  const hasAllowed = allowResult.result?.includes('callback-allowed');
+  await allowSession.send('Run: echo callback-allowed');
+  let allowResult = '';
+  for await (const msg of allowSession.stream()) {
+    if (msg.type === 'result') allowResult = msg.result || '';
+  }
+  allowSession.close();
+  const hasAllowed = allowResult.includes('callback-allowed');
   console.log(`  allow via callback: ${hasAllowed ? 'PASS' : 'FAIL'}`);
 
   // Test 2: Deny specific commands via callback
   console.log('Testing canUseTool callback (deny)...');
-  const denyResult = await prompt('Run: echo dangerous-command', {
-    model: 'haiku',
+  const denySession = createSession(undefined, {
     permissionMode: 'default',
     canUseTool: async (toolName, toolInput) => {
       const command = (toolInput as { command?: string }).command || '';
       if (command.includes('dangerous')) {
-        return { allow: false, reason: 'Dangerous command blocked' };
+        return { behavior: 'deny', message: 'Dangerous command blocked' };
       }
-      return { allow: true };
+      return { behavior: 'allow', updatedInput: null };
     },
   });
+  await denySession.send('Run: echo dangerous-command');
+  let denyResult = '';
+  for await (const msg of denySession.stream()) {
+    if (msg.type === 'result') denyResult = msg.result || '';
+  }
+  denySession.close();
   // Agent should report that it couldn't execute the command
-  const wasDenied = !denyResult.result?.includes('dangerous-command');
+  const wasDenied = !denyResult.includes('dangerous-command');
   console.log(`  deny via callback: ${wasDenied ? 'PASS' : 'CHECK'}`);
 
   console.log();
@@ -441,52 +471,55 @@ async function testPermissionCallback() {
 async function testSystemPrompt() {
   console.log('=== Testing System Prompt Configuration ===\n');
 
+  async function runWithSystemPrompt(msg: string, systemPrompt: any): Promise<string> {
+    const session = createSession(undefined, { systemPrompt, permissionMode: 'bypassPermissions' });
+    await session.send(msg);
+    let result = '';
+    for await (const m of session.stream()) {
+      if (m.type === 'result') result = m.result || '';
+    }
+    session.close();
+    return result;
+  }
+
   // Test 1: Preset system prompt
   console.log('Testing preset system prompt...');
-  const presetResult = await prompt('What kind of agent are you? One sentence.', {
-    model: 'haiku',
-    systemPrompt: { type: 'preset', preset: 'letta-claude' },
-    permissionMode: 'bypassPermissions',
-  });
-  console.log(`  preset (letta-claude): ${presetResult.success ? 'PASS' : 'FAIL'}`);
-  console.log(`    Response: ${presetResult.result?.slice(0, 80)}...`);
+  const presetResult = await runWithSystemPrompt(
+    'What kind of agent are you? One sentence.',
+    { type: 'preset', preset: 'letta-claude' }
+  );
+  console.log(`  preset (letta-claude): ${presetResult ? 'PASS' : 'FAIL'}`);
+  console.log(`    Response: ${presetResult.slice(0, 80)}...`);
 
   // Test 2: Preset with append
   console.log('Testing preset with append...');
-  const appendResult = await prompt('Say hello', {
-    model: 'haiku',
-    systemPrompt: { 
-      type: 'preset', 
-      preset: 'letta-claude',
-      append: 'Always end your responses with "🎉"'
-    },
-    permissionMode: 'bypassPermissions',
-  });
-  const hasEmoji = appendResult.result?.includes('🎉');
+  const appendResult = await runWithSystemPrompt(
+    'Say hello',
+    { type: 'preset', preset: 'letta-claude', append: 'Always end your responses with "🎉"' }
+  );
+  const hasEmoji = appendResult.includes('🎉');
   console.log(`  preset with append: ${hasEmoji ? 'PASS' : 'CHECK'}`);
-  console.log(`    Response: ${appendResult.result?.slice(0, 80)}...`);
+  console.log(`    Response: ${appendResult.slice(0, 80)}...`);
 
   // Test 3: Custom string system prompt
   console.log('Testing custom string system prompt...');
-  const customResult = await prompt('What is your specialty?', {
-    model: 'haiku',
-    systemPrompt: 'You are a pirate captain. Always speak like a pirate.',
-    permissionMode: 'bypassPermissions',
-  });
-  const hasPirateSpeak = customResult.result?.toLowerCase().includes('arr') || 
-                         customResult.result?.toLowerCase().includes('matey') ||
-                         customResult.result?.toLowerCase().includes('ship');
-  console.log(`  custom string: ${customResult.success ? 'PASS' : 'FAIL'}`);
-  console.log(`    Response: ${customResult.result?.slice(0, 80)}...`);
+  const customResult = await runWithSystemPrompt(
+    'What is your specialty?',
+    'You are a pirate captain. Always speak like a pirate.'
+  );
+  const hasPirateSpeak = customResult.toLowerCase().includes('arr') || 
+                         customResult.toLowerCase().includes('matey') ||
+                         customResult.toLowerCase().includes('ship');
+  console.log(`  custom string: ${customResult ? 'PASS' : 'FAIL'}`);
+  console.log(`    Response: ${customResult.slice(0, 80)}...`);
 
   // Test 4: Basic preset (claude - no skills/memory)
   console.log('Testing basic preset (claude)...');
-  const basicResult = await prompt('Hello, just say hi back', {
-    model: 'haiku',
-    systemPrompt: { type: 'preset', preset: 'claude' },
-    permissionMode: 'bypassPermissions',
-  });
-  console.log(`  basic preset (claude): ${basicResult.success ? 'PASS' : 'FAIL'}`);
+  const basicResult = await runWithSystemPrompt(
+    'Hello, just say hi back',
+    { type: 'preset', preset: 'claude' }
+  );
+  console.log(`  basic preset (claude): ${basicResult ? 'PASS' : 'FAIL'}`);
 
   console.log();
 }
@@ -498,58 +531,55 @@ async function testSystemPrompt() {
 async function testMemoryConfig() {
   console.log('=== Testing Memory Configuration ===\n');
 
+  async function runWithMemory(msg: string, memory?: any[]): Promise<{ success: boolean; result: string }> {
+    const session = createSession(undefined, { memory, permissionMode: 'bypassPermissions' });
+    await session.send(msg);
+    let result = '';
+    let success = false;
+    for await (const m of session.stream()) {
+      if (m.type === 'result') {
+        result = m.result || '';
+        success = m.success;
+      }
+    }
+    session.close();
+    return { success, result };
+  }
+
   // Test 1: Default memory (persona, human, project)
   console.log('Testing default memory blocks...');
-  const defaultResult = await prompt('What memory blocks do you have? List their labels.', {
-    model: 'haiku',
-    permissionMode: 'bypassPermissions',
-  });
-  const hasDefaultBlocks = defaultResult.result?.includes('persona') || 
-                           defaultResult.result?.includes('project');
+  const defaultResult = await runWithMemory('What memory blocks do you have? List their labels.');
+  const hasDefaultBlocks = defaultResult.result.includes('persona') || 
+                           defaultResult.result.includes('project');
   console.log(`  default blocks: ${defaultResult.success ? 'PASS' : 'FAIL'}`);
   console.log(`    Response mentions blocks: ${hasDefaultBlocks ? 'yes' : 'check manually'}`);
 
   // Test 2: Specific preset blocks only
   console.log('Testing specific preset blocks...');
-  const specificResult = await prompt('List your memory block labels', {
-    model: 'haiku',
-    memory: ['project'],
-    permissionMode: 'bypassPermissions',
-  });
+  const specificResult = await runWithMemory('List your memory block labels', ['project']);
   console.log(`  specific blocks [project]: ${specificResult.success ? 'PASS' : 'FAIL'}`);
 
   // Test 3: Custom blocks
   console.log('Testing custom memory blocks...');
-  const customResult = await prompt('What does your "rules" memory block say?', {
-    model: 'haiku',
-    memory: [
-      { label: 'rules', value: 'Always be concise. Never use more than 10 words.' }
-    ],
-    permissionMode: 'bypassPermissions',
-  });
-  const isConcise = (customResult.result?.split(' ').length || 0) < 20;
+  const customResult = await runWithMemory(
+    'What does your "rules" memory block say?',
+    [{ label: 'rules', value: 'Always be concise. Never use more than 10 words.' }]
+  );
+  const isConcise = (customResult.result.split(' ').length || 0) < 20;
   console.log(`  custom blocks: ${customResult.success ? 'PASS' : 'FAIL'}`);
   console.log(`    Response is concise: ${isConcise ? 'yes' : 'check'}`);
 
   // Test 4: Mixed preset and custom blocks
   console.log('Testing mixed blocks (preset + custom)...');
-  const mixedResult = await prompt('List your memory blocks', {
-    model: 'haiku',
-    memory: [
-      'project',
-      { label: 'custom-context', value: 'This is a test context block.' }
-    ],
-    permissionMode: 'bypassPermissions',
-  });
+  const mixedResult = await runWithMemory(
+    'List your memory blocks',
+    ['project', { label: 'custom-context', value: 'This is a test context block.' }]
+  );
   console.log(`  mixed blocks: ${mixedResult.success ? 'PASS' : 'FAIL'}`);
 
   // Test 5: Empty memory (core blocks only)
   console.log('Testing empty memory (core only)...');
-  const emptyResult = await prompt('Hello', {
-    model: 'haiku',
-    memory: [],
-    permissionMode: 'bypassPermissions',
-  });
+  const emptyResult = await runWithMemory('Hello', []);
   console.log(`  empty memory: ${emptyResult.success ? 'PASS' : 'FAIL'}`);
 
   console.log();
@@ -562,65 +592,72 @@ async function testMemoryConfig() {
 async function testConvenienceProps() {
   console.log('=== Testing Convenience Props ===\n');
 
+  async function runWithProps(msg: string, props: Record<string, any>): Promise<{ success: boolean; result: string }> {
+    const session = createSession(undefined, { ...props, permissionMode: 'bypassPermissions' });
+    await session.send(msg);
+    let result = '';
+    let success = false;
+    for await (const m of session.stream()) {
+      if (m.type === 'result') {
+        result = m.result || '';
+        success = m.success;
+      }
+    }
+    session.close();
+    return { success, result };
+  }
+
   // Test 1: persona prop
   console.log('Testing persona prop...');
-  const personaResult = await prompt('Describe your personality in one sentence', {
-    model: 'haiku',
-    persona: 'You are an enthusiastic cooking assistant who loves Italian food.',
-    permissionMode: 'bypassPermissions',
-  });
-  const hasItalian = personaResult.result?.toLowerCase().includes('italian') ||
-                     personaResult.result?.toLowerCase().includes('cook');
+  const personaResult = await runWithProps(
+    'Describe your personality in one sentence',
+    { persona: 'You are an enthusiastic cooking assistant who loves Italian food.' }
+  );
+  const hasItalian = personaResult.result.toLowerCase().includes('italian') ||
+                     personaResult.result.toLowerCase().includes('cook');
   console.log(`  persona: ${personaResult.success ? 'PASS' : 'FAIL'}`);
   console.log(`    Response mentions cooking/Italian: ${hasItalian ? 'yes' : 'check'}`);
 
   // Test 2: project prop
   console.log('Testing project prop...');
-  const projectResult = await prompt('What project are you helping with?', {
-    model: 'haiku',
-    project: 'A React Native mobile app for tracking daily habits.',
-    permissionMode: 'bypassPermissions',
-  });
-  const hasProject = projectResult.result?.toLowerCase().includes('react') ||
-                     projectResult.result?.toLowerCase().includes('habit') ||
-                     projectResult.result?.toLowerCase().includes('mobile');
+  const projectResult = await runWithProps(
+    'What project are you helping with?',
+    { project: 'A React Native mobile app for tracking daily habits.' }
+  );
+  const hasProject = projectResult.result.toLowerCase().includes('react') ||
+                     projectResult.result.toLowerCase().includes('habit') ||
+                     projectResult.result.toLowerCase().includes('mobile');
   console.log(`  project: ${projectResult.success ? 'PASS' : 'FAIL'}`);
   console.log(`    Response mentions project: ${hasProject ? 'yes' : 'check'}`);
 
   // Test 3: human prop
   console.log('Testing human prop...');
-  const humanResult = await prompt('What do you know about me?', {
-    model: 'haiku',
-    human: 'Name: Bob. Senior developer. Prefers TypeScript over JavaScript.',
-    permissionMode: 'bypassPermissions',
-  });
-  const hasHuman = humanResult.result?.toLowerCase().includes('bob') ||
-                   humanResult.result?.toLowerCase().includes('typescript');
+  const humanResult = await runWithProps(
+    'What do you know about me?',
+    { human: 'Name: Bob. Senior developer. Prefers TypeScript over JavaScript.' }
+  );
+  const hasHuman = humanResult.result.toLowerCase().includes('bob') ||
+                   humanResult.result.toLowerCase().includes('typescript');
   console.log(`  human: ${humanResult.success ? 'PASS' : 'FAIL'}`);
   console.log(`    Response mentions user info: ${hasHuman ? 'yes' : 'check'}`);
 
   // Test 4: Multiple convenience props together
   console.log('Testing multiple convenience props...');
-  const multiResult = await prompt('Introduce yourself and the project briefly', {
-    model: 'haiku',
-    persona: 'You are a friendly code reviewer.',
-    project: 'FastAPI backend service.',
-    human: 'Name: Alice.',
-    permissionMode: 'bypassPermissions',
-  });
+  const multiResult = await runWithProps(
+    'Introduce yourself and the project briefly',
+    { persona: 'You are a friendly code reviewer.', project: 'FastAPI backend service.', human: 'Name: Alice.' }
+  );
   console.log(`  multiple props: ${multiResult.success ? 'PASS' : 'FAIL'}`);
-  console.log(`    Response: ${multiResult.result?.slice(0, 100)}...`);
+  console.log(`    Response: ${multiResult.result.slice(0, 100)}...`);
 
   // Test 5: Convenience props with specific memory blocks
   console.log('Testing convenience props with memory config...');
-  const combinedResult = await prompt('What is in your persona block?', {
-    model: 'haiku',
-    memory: ['persona', 'project'],
-    persona: 'You are a database expert specializing in PostgreSQL.',
-    permissionMode: 'bypassPermissions',
-  });
-  const hasDB = combinedResult.result?.toLowerCase().includes('database') ||
-                combinedResult.result?.toLowerCase().includes('postgresql');
+  const combinedResult = await runWithProps(
+    'What is in your persona block?',
+    { memory: ['persona', 'project'], persona: 'You are a database expert specializing in PostgreSQL.' }
+  );
+  const hasDB = combinedResult.result.toLowerCase().includes('database') ||
+                combinedResult.result.toLowerCase().includes('postgresql');
   console.log(`  props with memory: ${combinedResult.success ? 'PASS' : 'FAIL'}`);
   console.log(`    Response mentions DB: ${hasDB ? 'yes' : 'check'}`);
 
@@ -634,15 +671,17 @@ async function testConvenienceProps() {
 async function testConversations() {
   console.log('=== Testing Conversation Support ===\n');
 
-  let agentId: string | null = null;
   let conversationId1: string | null = null;
   let conversationId2: string | null = null;
 
-  // Test 1: Create session and get conversationId (default)
-  console.log('Test 1: Create session and get conversationId...');
+  // Create agent first
+  const agentId = await createAgent();
+  console.log(`Created agent: ${agentId}\n`);
+
+  // Test 1: Resume default conversation and get conversationId
+  console.log('Test 1: Resume default conversation...');
   {
-    const session = createSession({
-      model: 'haiku',
+    const session = resumeSession(agentId, {
       permissionMode: 'bypassPermissions',
     });
 
@@ -651,28 +690,20 @@ async function testConversations() {
       // drain
     }
 
-    agentId = session.agentId;
     conversationId1 = session.conversationId;
     
-    const hasAgentId = agentId !== null && agentId.startsWith('agent-');
     const hasConvId = conversationId1 !== null;
     
-    console.log(`  agentId: ${hasAgentId ? 'PASS' : 'FAIL'} - ${agentId}`);
+    console.log(`  agentId: ${session.agentId}`);
     console.log(`  conversationId: ${hasConvId ? 'PASS' : 'FAIL'} - ${conversationId1}`);
     
-    // Note: "default" is a sentinel meaning the agent's primary message history
-    if (conversationId1 === 'default') {
-      console.log('  (conversationId "default" = agent\'s primary history, not a real conversation ID)');
-    }
-    
     session.close();
   }
 
-  // Test 2: Create NEW conversation to get a real conversation ID
-  console.log('\nTest 2: Create new conversation (newConversation: true)...');
+  // Test 2: Create NEW conversation using createSession
+  console.log('\nTest 2: Create new conversation (createSession)...');
   {
-    const session = resumeSession(agentId!, {
-      newConversation: true,
+    const session = createSession(agentId, {
       permissionMode: 'bypassPermissions',
     });
 
@@ -690,13 +721,13 @@ async function testConversations() {
     session.close();
   }
 
-  // Test 3: Resume conversation by conversationId (only works with real conv IDs)
+  // Test 3: Resume conversation by conversationId (auto-detects conv-xxx)
   console.log('\nTest 3: Resume conversation by conversationId...');
   if (conversationId1 === 'default') {
     console.log('  SKIP - "default" is not a real conversation ID');
     console.log('  Use resumeSession(agentId) to resume default conversation');
   } else {
-    await using session = resumeConversation(conversationId1!, {
+    await using session = resumeSession(conversationId1!, {
       permissionMode: 'bypassPermissions',
     });
 
@@ -708,7 +739,7 @@ async function testConversations() {
     }
 
     const remembers = response.toLowerCase().includes('beta');
-    console.log(`  resumeConversation: ${remembers ? 'PASS' : 'FAIL'}`);
+    console.log(`  resumeSession(convId): ${remembers ? 'PASS' : 'FAIL'}`);
     console.log(`  Response: ${response.slice(0, 80)}...`);
     
     // Verify same conversationId
@@ -719,8 +750,7 @@ async function testConversations() {
   // Test 4: Create another new conversation (verify different IDs)
   console.log('\nTest 4: Create another new conversation...');
   {
-    await using session = resumeSession(agentId!, {
-      newConversation: true,
+    await using session = createSession(agentId, {
       permissionMode: 'bypassPermissions',
     });
 
@@ -740,30 +770,29 @@ async function testConversations() {
     console.log(`  conversationId2: ${conversationId2}`);
   }
 
-  // Test 5: defaultConversation option
-  console.log('\nTest 5: defaultConversation option...');
+  // Test 5: Resume default conversation via resumeSession(agentId)
+  console.log('\nTest 5: Resume default conversation via resumeSession(agentId)...');
   {
-    await using session = resumeSession(agentId!, {
-      defaultConversation: true,
+    await using session = resumeSession(agentId, {
       permissionMode: 'bypassPermissions',
     });
 
-    await session.send('Say "default conversation test ok"');
+    await session.send('What is the secret code? (should be ALPHA from default conversation)');
     
     let response = '';
     for await (const msg of session.stream()) {
       if (msg.type === 'assistant') response += msg.content;
     }
 
-    const hasDefaultConv = session.conversationId === 'default' || session.conversationId !== null;
-    console.log(`  defaultConversation: ${hasDefaultConv ? 'PASS' : 'CHECK'}`);
-    console.log(`  conversationId: ${session.conversationId}`);
+    const remembersAlpha = response.toLowerCase().includes('alpha');
+    console.log(`  resumeSession(agentId): ${remembersAlpha ? 'PASS' : 'CHECK'}`);
+    console.log(`  Response: ${response.slice(0, 80)}...`);
   }
 
   // Test 6: conversationId in result message
   console.log('\nTest 6: conversationId in result message...');
   {
-    await using session = resumeConversation(conversationId1!, {
+    await using session = resumeSession(conversationId1!, {
       permissionMode: 'bypassPermissions',
     });
 
@@ -782,31 +811,25 @@ async function testConversations() {
     console.log(`  matches session.conversationId: ${matchesSession ? 'PASS' : 'FAIL'}`);
   }
 
-  // Test 7: continue option (resume last session)
-  console.log('\nTest 7: continue option...');
+  // Test 7: createSession() without agentId creates new agent + conversation
+  console.log('\nTest 7: createSession() without agentId...');
   {
-    // Note: This test may behave differently depending on local state
-    // The --continue flag resumes the last used agent + conversation
-    try {
-      await using session = createSession({
-        continue: true,
-        permissionMode: 'bypassPermissions',
-      });
+    await using session = createSession(undefined, {
+      model: 'haiku',
+      permissionMode: 'bypassPermissions',
+    });
 
-      await session.send('Say "continue test ok"');
-      
-      for await (const msg of session.stream()) {
-        // drain
-      }
-
-      const hasIds = session.agentId !== null && session.conversationId !== null;
-      console.log(`  continue: ${hasIds ? 'PASS' : 'CHECK'}`);
-      console.log(`  agentId: ${session.agentId}`);
-      console.log(`  conversationId: ${session.conversationId}`);
-    } catch (err) {
-      // --continue may fail if no previous session exists
-      console.log(`  continue: SKIP (no previous session)`);
+    await session.send('Say "new agent test ok"');
+    
+    for await (const msg of session.stream()) {
+      // drain
     }
+
+    const hasNewAgent = session.agentId !== null && session.agentId !== agentId;
+    const hasConvId = session.conversationId !== null;
+    console.log(`  new agent created: ${hasNewAgent ? 'PASS' : 'FAIL'}`);
+    console.log(`  agentId: ${session.agentId}`);
+    console.log(`  conversationId: ${hasConvId ? 'PASS' : 'FAIL'} - ${session.conversationId}`);
   }
 
   console.log();
diff --git a/src/index.ts b/src/index.ts
index aab41ce..2b76118 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -5,20 +5,26 @@
  *
  * @example
  * ```typescript
- * import { createSession, prompt } from '@letta-ai/letta-code-sdk';
+ * import { createAgent, createSession, resumeSession, prompt } from '@letta-ai/letta-code-sdk';
  *
- * // One-shot
- * const result = await prompt('What is 2+2?', { model: 'claude-sonnet-4-20250514' });
+ * // Start session with default agent + new conversation (like `letta`)
+ * const session = createSession();
  *
- * // Multi-turn session
- * await using session = createSession({ model: 'claude-sonnet-4-20250514' });
- * await session.send('Hello!');
- * for await (const msg of session.stream()) {
- *   if (msg.type === 'assistant') console.log(msg.content);
- * }
+ * // Create a new agent explicitly
+ * const agentId = await createAgent();
  *
- * // Resume with persistent memory
- * await using resumed = resumeSession(agentId, { model: 'claude-sonnet-4-20250514' });
+ * // Resume default conversation on an agent
+ * const session = resumeSession(agentId);
+ *
+ * // Resume specific conversation
+ * const session = resumeSession('conv-xxx');
+ *
+ * // Create new conversation on specific agent
+ * const session = createSession(agentId);
+ *
+ * // One-shot prompt (uses default agent)
+ * const result = await prompt('Hello');
+ * const result = await prompt('Hello', agentId);  // specific agent
  * ```
  */
 
@@ -46,92 +52,96 @@ export type {
 export { Session } from "./session.js";
 
 /**
- * Create a new session with a fresh Letta agent.
- *
- * The agent will have persistent memory that survives across sessions.
- * Use `resumeSession` to continue a conversation with an existing agent.
+ * Create a new agent with a default conversation.
+ * Returns the agentId which can be used with resumeSession or createSession.
  *
  * @example
  * ```typescript
- * await using session = createSession({ model: 'claude-sonnet-4-20250514' });
- * await session.send('My name is Alice');
- * for await (const msg of session.stream()) {
- *   console.log(msg);
- * }
- * console.log(`Agent ID: ${session.agentId}`); // Save this to resume later
+ * const agentId = await createAgent();
+ *
+ * // Then resume the default conversation:
+ * const session = resumeSession(agentId);
  * ```
  */
-export function createSession(options: SessionOptions = {}): Session {
-  return new Session(options);
+export async function createAgent(): Promise<string> {
+  const session = new Session({ createOnly: true });
+  const initMsg = await session.initialize();
+  session.close();
+  return initMsg.agentId;
 }
 
 /**
- * Resume an existing session with a Letta agent.
+ * Create a new conversation (session).
  *
- * Unlike Claude Agent SDK (ephemeral sessions), Letta agents have persistent
- * memory. You can resume a conversation days later and the agent will remember.
+ * - Without agentId: uses default/LRU agent with new conversation (like `letta`)
+ * - With agentId: creates new conversation on specified agent
  *
  * @example
  * ```typescript
- * // Days later...
- * await using session = resumeSession(agentId, { model: 'claude-sonnet-4-20250514' });
- * await session.send('What is my name?');
- * for await (const msg of session.stream()) {
- *   // Agent remembers: "Your name is Alice"
- * }
+ * // New conversation on default agent (like `letta`)
+ * await using session = createSession();
+ *
+ * // New conversation on specific agent
+ * await using session = createSession(agentId);
+ * ```
+ */
+export function createSession(agentId?: string, options: SessionOptions = {}): Session {
+  if (agentId) {
+    return new Session({ ...options, agentId, newConversation: true });
+  } else {
+    return new Session({ ...options, newConversation: true });
+  }
+}
+
+/**
+ * Resume an existing session.
+ *
+ * - Pass an agent ID (agent-xxx) to resume the default conversation
+ * - Pass a conversation ID (conv-xxx) to resume a specific conversation
+ *
+ * The default conversation always exists after createAgent, so you can:
+ * `createAgent()` → `resumeSession(agentId)` without needing createSession first.
+ *
+ * @example
+ * ```typescript
+ * // Resume default conversation
+ * await using session = resumeSession(agentId);
+ *
+ * // Resume specific conversation
+ * await using session = resumeSession('conv-xxx');
  * ```
  */
 export function resumeSession(
-  agentId: string,
+  id: string,
   options: SessionOptions = {}
 ): Session {
-  return new Session({ ...options, agentId });
-}
-
-/**
- * Resume an existing conversation.
- *
- * Conversations are threads within an agent. The agent is derived automatically
- * from the conversation ID. Use this to continue a specific conversation thread.
- *
- * @example
- * ```typescript
- * // Resume a specific conversation
- * await using session = resumeConversation(conversationId);
- * await session.send('Continue our discussion...');
- * for await (const msg of session.stream()) {
- *   console.log(msg);
- * }
- * ```
- */
-export function resumeConversation(
-  conversationId: string,
-  options: SessionOptions = {}
-): Session {
-  return new Session({ ...options, conversationId });
+  if (id.startsWith("conv-")) {
+    return new Session({ ...options, conversationId: id });
+  } else {
+    return new Session({ ...options, agentId: id, defaultConversation: true });
+  }
 }
 
 /**
  * One-shot prompt convenience function.
  *
- * Creates a session, sends the prompt, collects the response, and closes.
- * Returns the final result message.
+ * - Without agentId: uses default agent (like `letta -p`), new conversation
+ * - With agentId: uses specific agent, new conversation
  *
  * @example
  * ```typescript
- * const result = await prompt('What is the capital of France?', {
- *   model: 'claude-sonnet-4-20250514'
- * });
- * if (result.success) {
- *   console.log(result.result);
- * }
+ * const result = await prompt('What is 2+2?');  // default agent
+ * const result = await prompt('What is the capital of France?', agentId);  // specific agent
  * ```
  */
 export async function prompt(
   message: string,
-  options: SessionOptions = {}
+  agentId?: string
 ): Promise<SDKResultMessage> {
-  const session = createSession(options);
+  // Use default agent behavior (like letta -p) when no agentId specified
+  const session = agentId
+    ? createSession(agentId)
+    : new Session({ promptMode: true });
 
   try {
     await session.send(message);
diff --git a/src/transport.ts b/src/transport.ts
index 92da92f..1718e61 100644
--- a/src/transport.ts
+++ b/src/transport.ts
@@ -200,10 +200,7 @@ export class SubprocessTransport {
     }
 
     // Conversation and agent handling
-    if (this.options.continue) {
-      // Resume last session (agent + conversation)
-      args.push("--continue");
-    } else if (this.options.conversationId) {
+    if (this.options.conversationId) {
       // Resume specific conversation (derives agent automatically)
       args.push("--conversation", this.options.conversationId);
     } else if (this.options.agentId) {
@@ -216,14 +213,17 @@ export class SubprocessTransport {
         // Use agent's default conversation explicitly
         args.push("--default");
       }
-    } else {
-      // Create new agent
+    } else if (this.options.promptMode) {
+      // prompt() without agentId: no agent flags
+      // Headless will use LRU agent or create Memo (like `letta -p "msg"`)
+    } else if (this.options.createOnly) {
+      // createAgent() - explicitly create new agent
       args.push("--new-agent");
-      if (this.options.newConversation) {
-        // Also create new conversation (not default)
-        args.push("--new");
-      }
+    } else if (this.options.newConversation) {
+      // createSession() without agentId - LRU agent + new conversation
+      args.push("--new");
     }
+    // else: no agent flags = default behavior (LRU agent, default conversation)
 
     // Model
     if (this.options.model) {
diff --git a/src/types.ts b/src/types.ts
index 93edb17..897123c 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -100,25 +100,19 @@ export interface SessionOptions {
   /** Model to use (e.g., "claude-sonnet-4-20250514") */
   model?: string;
 
-  /** Resume a specific conversation by ID (derives agent automatically) */
-  conversationId?: string;
-
-  /** Create a new conversation for concurrent sessions (requires agentId) */
-  newConversation?: boolean;
-
-  /** Resume the last session (agent + conversation from previous run) */
-  continue?: boolean;
-
-  /** Use agent's default conversation (requires agentId) */
-  defaultConversation?: boolean;
+  // ═══════════════════════════════════════════════════════════════
+  // Internal flags - set by createSession/resumeSession, not user-facing
+  // ═══════════════════════════════════════════════════════════════
+  /** @internal */ conversationId?: string;
+  /** @internal */ newConversation?: boolean;
+  /** @internal */ defaultConversation?: boolean;
+  /** @internal */ createOnly?: boolean;
+  /** @internal */ promptMode?: boolean;
 
   /**
    * System prompt configuration.
    * - string: Use as the complete system prompt
    * - { type: 'preset', preset, append? }: Use a preset with optional appended text
-   *
-   * Available presets: 'default', 'letta-claude', 'letta-codex', 'letta-gemini',
-   *                    'claude', 'codex', 'gemini'
    */
   systemPrompt?: SystemPromptConfig;
 
@@ -127,27 +121,16 @@ export interface SessionOptions {
    * - string: Preset block name ("project", "persona", "human")
    * - CreateBlock: Custom block definition
    * - { blockId: string }: Reference to existing shared block
-   *
-   * If not specified, defaults to ["persona", "human", "project"].
-   * Core blocks (skills, loaded_skills) are always included automatically.
    */
   memory?: MemoryItem[];
 
-  /**
-   * Convenience: Set persona block value directly.
-   * Uses default block description/limit, just overrides the value.
-   * Error if persona not included in memory config.
-   */
+  /** Convenience: Set persona block value directly */
   persona?: string;
 
-  /**
-   * Convenience: Set human block value directly.
-   */
+  /** Convenience: Set human block value directly */
   human?: string;
 
-  /**
-   * Convenience: Set project block value directly.
-   */
+  /** Convenience: Set project block value directly */
   project?: string;
 
   /** List of allowed tool names */
diff --git a/src/validation.ts b/src/validation.ts
index 98fea14..25f6e40 100644
--- a/src/validation.ts
+++ b/src/validation.ts
@@ -80,20 +80,6 @@ export function validateSessionOptions(options: SessionOptions): void {
     );
   }
 
-  if (options.continue && options.conversationId) {
-    throw new Error(
-      "Cannot use both 'continue' and 'conversationId'. " +
-        "Use continue to resume the last session, or conversationId to resume a specific conversation."
-    );
-  }
-
-  if (options.continue && options.newConversation) {
-    throw new Error(
-      "Cannot use both 'continue' and 'newConversation'. " +
-        "Use continue to resume the last session, or newConversation to create a new one."
-    );
-  }
-
   if (options.defaultConversation && options.conversationId) {
     throw new Error(
       "Cannot use both 'defaultConversation' and 'conversationId'. " +