Moving the copilot-sdk cookbook content in here

cookbook/copilot-sdk/nodejs/persisting-sessions.md

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+# Session Persistence and Resumption
+
+Save and restore conversation sessions across application restarts.
+
+## Example scenario
+
+You want users to be able to continue a conversation even after closing and reopening your application.
+
+> **Runnable example:** [recipe/persisting-sessions.ts](recipe/persisting-sessions.ts)
+>
+> ```bash
+> cd recipe && npm install
+> npx tsx persisting-sessions.ts
+> # or: npm run persisting-sessions
+> ```
+
+### Creating a session with a custom ID
+
+```typescript
+import { CopilotClient } from "@github/copilot-sdk";
+
+const client = new CopilotClient();
+await client.start();
+
+// Create session with a memorable ID
+const session = await client.createSession({
+    sessionId: "user-123-conversation",
+    model: "gpt-5",
+});
+
+await session.sendAndWait({ prompt: "Let's discuss TypeScript generics" });
+
+// Session ID is preserved
+console.log(session.sessionId); // "user-123-conversation"
+
+// Destroy session but keep data on disk
+await session.destroy();
+await client.stop();
+```
+
+### Resuming a session
+
+```typescript
+const client = new CopilotClient();
+await client.start();
+
+// Resume the previous session
+const session = await client.resumeSession("user-123-conversation");
+
+// Previous context is restored
+await session.sendAndWait({ prompt: "What were we discussing?" });
+// AI remembers the TypeScript generics discussion
+
+await session.destroy();
+await client.stop();
+```
+
+### Listing available sessions
+
+```typescript
+const sessions = await client.listSessions();
+console.log(sessions);
+// [
+//   { sessionId: "user-123-conversation", ... },
+//   { sessionId: "user-456-conversation", ... },
+// ]
+```
+
+### Deleting a session permanently
+
+```typescript
+// Remove session and all its data from disk
+await client.deleteSession("user-123-conversation");
+```
+
+## Getting session history
+
+Retrieve all messages from a session:
+
+```typescript
+const messages = await session.getMessages();
+for (const msg of messages) {
+    console.log(`[${msg.type}]`, msg.data);
+}
+```
+
+## Best practices
+
+1. **Use meaningful session IDs**: Include user ID or context in the session ID
+2. **Handle missing sessions**: Check if a session exists before resuming
+3. **Clean up old sessions**: Periodically delete sessions that are no longer needed