Moving the copilot-sdk cookbook content in here

cookbook/copilot-sdk/go/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.go](recipe/persisting-sessions.go)
+>
+> ```bash
+> cd recipe
+> go run persisting-sessions.go
+> ```
+
+### Creating a session with a custom ID
+
+```go
+package main
+
+import (
+    "fmt"
+    "github.com/github/copilot-sdk/go"
+)
+
+func main() {
+    client := copilot.NewClient()
+    client.Start()
+    defer client.Stop()
+
+    // Create session with a memorable ID
+    session, _ := client.CreateSession(copilot.SessionConfig{
+        SessionID: "user-123-conversation",
+        Model:     "gpt-5",
+    })
+
+    session.Send(copilot.MessageOptions{Prompt: "Let's discuss TypeScript generics"})
+
+    // Session ID is preserved
+    fmt.Println(session.SessionID)
+
+    // Destroy session but keep data on disk
+    session.Destroy()
+}
+```
+
+### Resuming a session
+
+```go
+client := copilot.NewClient()
+client.Start()
+defer client.Stop()
+
+// Resume the previous session
+session, _ := client.ResumeSession("user-123-conversation")
+
+// Previous context is restored
+session.Send(copilot.MessageOptions{Prompt: "What were we discussing?"})
+
+session.Destroy()
+```
+
+### Listing available sessions
+
+```go
+sessions, _ := client.ListSessions()
+for _, s := range sessions {
+    fmt.Println("Session:", s.SessionID)
+}
+```
+
+### Deleting a session permanently
+
+```go
+// Remove session and all its data from disk
+client.DeleteSession("user-123-conversation")
+```
+
+### Getting session history
+
+```go
+messages, _ := session.GetMessages()
+for _, msg := range messages {
+    fmt.Printf("[%s] %v\n", 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