use antigravity to rewrite all your code to migrate from flat files to relational database. YOLO

server/session.go

@@ -2,12 +2,10 @@ package main
 
 import (
 	"crypto/rand"
+	"database/sql"
 	"encoding/base64"
-	"encoding/json"
 	"fmt"
 	"net/http"
-	"os"
-	"path/filepath"
 	"time"
 )
 
@@ -54,32 +52,24 @@ func CreateSession(fitbitUserID string) (*Session, error) {
 	return session, nil
 }
 
-// SaveSession persists a session to disk
+// SaveSession persists a session to the database
 func SaveSession(session *Session) error {
-	sessionDir := "data/sessions"
-	if err := os.MkdirAll(sessionDir, 0755); err != nil {
-		return fmt.Errorf("failed to create sessions directory: %w", err)
-	}
-
-	sessionPath := filepath.Join(sessionDir, session.Token+".json")
-	data, err := json.MarshalIndent(session, "", "  ")
-	if err != nil {
-		return err
-	}
-
-	return os.WriteFile(sessionPath, data, 0600)
+	_, err := db.Exec(`
+		INSERT INTO sessions (token, fitbit_user_id, created_at, expires_at)
+		VALUES (?, ?, ?, ?)
+	`, session.Token, session.FitbitUserID, session.CreatedAt, session.ExpiresAt)
+	return err
 }
 
-// LoadSession loads a session from disk by token
+// LoadSession loads a session from the database by token
 func LoadSession(token string) (*Session, error) {
-	sessionPath := filepath.Join("data/sessions", token+".json")
-	data, err := os.ReadFile(sessionPath)
-	if err != nil {
-		return nil, err
-	}
-
 	var session Session
-	if err := json.Unmarshal(data, &session); err != nil {
+	err := db.QueryRow("SELECT token, fitbit_user_id, created_at, expires_at FROM sessions WHERE token = ?", token).
+		Scan(&session.Token, &session.FitbitUserID, &session.CreatedAt, &session.ExpiresAt)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return nil, fmt.Errorf("session not found")
+		}
 		return nil, err
 	}
 
@@ -92,10 +82,10 @@ func LoadSession(token string) (*Session, error) {
 	return &session, nil
 }
 
-// DeleteSession removes a session from disk
+// DeleteSession removes a session from the database
 func DeleteSession(token string) error {
-	sessionPath := filepath.Join("data/sessions", token+".json")
-	return os.Remove(sessionPath)
+	_, err := db.Exec("DELETE FROM sessions WHERE token = ?", token)
+	return err
 }
 
 // GetSessionFromRequest extracts the session from the request cookie