diff --git a/Services/ServiceTrackerDataStore.cs b/Services/ServiceTrackerDataStore.cs
new file mode 100644
index 0000000..0fb2a95
--- /dev/null
+++ b/Services/ServiceTrackerDataStore.cs
@@ -0,0 +1,135 @@
+using Disco.Plugins.ServiceTracker.Models;
+using Newtonsoft.Json;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+
+namespace Disco.Plugins.ServiceTracker.Services
+{
+    /// <summary>
+    /// JSON file-based data store for ServiceTracker metadata.
+    /// Stores ticket extensions and configuration in the plugin data directory.
+    /// </summary>
+    public class ServiceTrackerDataStore
+    {
+        private readonly string _dataDirectory;
+        private readonly string _ticketsPath;
+        private readonly string _configPath;
+        private static readonly object _lock = new object();
+
+        public ServiceTrackerDataStore(string pluginDataDirectory)
+        {
+            _dataDirectory = pluginDataDirectory;
+            _ticketsPath = Path.Combine(_dataDirectory, "tickets.json");
+            _configPath = Path.Combine(_dataDirectory, "config.json");
+
+            if (!Directory.Exists(_dataDirectory))
+                Directory.CreateDirectory(_dataDirectory);
+        }
+
+        // --- Configuration ---
+
+        public ServiceTrackerConfig LoadConfig()
+        {
+            lock (_lock)
+            {
+                if (!File.Exists(_configPath))
+                {
+                    var defaultConfig = ServiceTrackerConfig.CreateDefault();
+                    SaveConfig(defaultConfig);
+                    return defaultConfig;
+                }
+                var json = File.ReadAllText(_configPath);
+                return JsonConvert.DeserializeObject<ServiceTrackerConfig>(json) ?? ServiceTrackerConfig.CreateDefault();
+            }
+        }
+
+        public void SaveConfig(ServiceTrackerConfig config)
+        {
+            lock (_lock)
+            {
+                var json = JsonConvert.SerializeObject(config, Formatting.Indented);
+                File.WriteAllText(_configPath, json);
+            }
+        }
+
+        // --- Tickets ---
+
+        public List<ServiceTicket> LoadAllTickets()
+        {
+            lock (_lock)
+            {
+                if (!File.Exists(_ticketsPath))
+                    return new List<ServiceTicket>();
+
+                var json = File.ReadAllText(_ticketsPath);
+                return JsonConvert.DeserializeObject<List<ServiceTicket>>(json) ?? new List<ServiceTicket>();
+            }
+        }
+
+        public ServiceTicket GetTicket(int jobId)
+        {
+            return LoadAllTickets().FirstOrDefault(t => t.JobId == jobId);
+        }
+
+        public void SaveTicket(ServiceTicket ticket)
+        {
+            lock (_lock)
+            {
+                var tickets = LoadAllTicketsUnsafe();
+                var existing = tickets.FindIndex(t => t.JobId == ticket.JobId);
+                ticket.LastModifiedDate = DateTime.Now;
+
+                if (existing >= 0)
+                    tickets[existing] = ticket;
+                else
+                    tickets.Add(ticket);
+
+                SaveAllTicketsUnsafe(tickets);
+            }
+        }
+
+        public void DeleteTicket(int jobId)
+        {
+            lock (_lock)
+            {
+                var tickets = LoadAllTicketsUnsafe();
+                tickets.RemoveAll(t => t.JobId == jobId);
+                SaveAllTicketsUnsafe(tickets);
+            }
+        }
+
+        public void AddNote(int jobId, TicketNote note)
+        {
+            lock (_lock)
+            {
+                var tickets = LoadAllTicketsUnsafe();
+                var ticket = tickets.FirstOrDefault(t => t.JobId == jobId);
+                if (ticket != null)
+                {
+                    if (ticket.Notes == null)
+                        ticket.Notes = new List<TicketNote>();
+                    ticket.Notes.Add(note);
+                    ticket.LastModifiedDate = DateTime.Now;
+                    SaveAllTicketsUnsafe(tickets);
+                }
+            }
+        }
+
+        // Internal methods (caller must hold lock)
+        private List<ServiceTicket> LoadAllTicketsUnsafe()
+        {
+            if (!File.Exists(_ticketsPath))
+                return new List<ServiceTicket>();
+            var json = File.ReadAllText(_ticketsPath);
+            return JsonConvert.DeserializeObject<List<ServiceTicket>>(json) ?? new List<ServiceTicket>();
+        }
+
+        private void SaveAllTicketsUnsafe(List<ServiceTicket> tickets)
+        {
+            var json = JsonConvert.SerializeObject(tickets, Formatting.Indented);
+            File.WriteAllText(_ticketsPath, json);
+        }
+    }
+}