TASK 10: Polar billing + Velopack auto-updates (steps 1-7)

Services/LayoutStore.cs

@@ -1027,6 +1027,76 @@ public class LayoutStore : IDisposable
         return (string)cmd.ExecuteScalar()!;
     }
 
+    // ─── License (TASK 10 — Polar billing) ───
+
+    /// <summary>The saved license key, or null if never entered.</summary>
+    public string? LoadLicenseKey()
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "SELECT Value FROM Settings WHERE Key = 'LicenseKey';";
+        var value = cmd.ExecuteScalar() as string;
+        return string.IsNullOrWhiteSpace(value) ? null : value;
+    }
+
+    public void SaveLicenseKey(string? key)
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "DELETE FROM Settings WHERE Key = 'LicenseKey';";
+        cmd.ExecuteNonQuery();
+        if (string.IsNullOrWhiteSpace(key)) return;
+
+        using var insert = _connection.CreateCommand();
+        insert.CommandText = "INSERT INTO Settings (Key, Value) VALUES ('LicenseKey', $value);";
+        insert.Parameters.AddWithValue("$value", key);
+        insert.ExecuteNonQuery();
+    }
+
+    /// <summary>When the license was last validated online (ISO 8601), or null if never.</summary>
+    public DateTime? LoadLicenseValidatedAt()
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "SELECT Value FROM Settings WHERE Key = 'LicenseValidatedAt';";
+        var value = cmd.ExecuteScalar() as string;
+        if (string.IsNullOrWhiteSpace(value)) return null;
+        return DateTime.TryParse(value, out var dt) ? dt : null;
+    }
+
+    public void SaveLicenseValidatedAt(DateTime? dt)
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "DELETE FROM Settings WHERE Key = 'LicenseValidatedAt';";
+        cmd.ExecuteNonQuery();
+        if (dt == null) return;
+
+        using var insert = _connection.CreateCommand();
+        insert.CommandText = "INSERT INTO Settings (Key, Value) VALUES ('LicenseValidatedAt', $value);";
+        insert.Parameters.AddWithValue("$value", dt.Value.ToString("o"));
+        insert.ExecuteNonQuery();
+    }
+
+    /// <summary>Cached premium state (1 = premium, 0 = free). Used for offline
+    /// grace period — the app checks online at startup but uses this cached
+    /// value when offline.</summary>
+    public bool LoadIsPremium()
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "SELECT Value FROM Settings WHERE Key = 'IsPremium';";
+        var value = cmd.ExecuteScalar() as string;
+        return value == "1";
+    }
+
+    public void SaveIsPremium(bool isPremium)
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "DELETE FROM Settings WHERE Key = 'IsPremium';";
+        cmd.ExecuteNonQuery();
+
+        using var insert = _connection.CreateCommand();
+        insert.CommandText = "INSERT INTO Settings (Key, Value) VALUES ('IsPremium', $value);";
+        insert.Parameters.AddWithValue("$value", isPremium ? "1" : "0");
+        insert.ExecuteNonQuery();
+    }
+
     public void Dispose()
     {
         _connection.Dispose();

Services/PolarLicenseService.cs

@@ -0,0 +1,87 @@
+using System.Net.Http;
+using System.Net.Http.Json;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// Validates LlamaCasty license keys against the Polar.sh customer-portal API.
+/// No auth required for client-side validation — the endpoint is public by design.
+/// </summary>
+public class PolarLicenseService
+{
+    private const string ValidateUrl = "https://api.polar.sh/v1/customer-portal/license-keys/validate";
+    public const string OrganizationId = "c05fb364-b967-4f6c-adf2-8a144e46d085";
+
+    private readonly HttpClient _http;
+
+    public PolarLicenseService(HttpClient? http = null)
+    {
+        _http = http ?? new HttpClient { Timeout = TimeSpan.FromSeconds(15) };
+    }
+
+    public async Task<LicenseValidationResult> ValidateAsync(string key, CancellationToken ct = default)
+    {
+        if (string.IsNullOrWhiteSpace(key))
+            return new LicenseValidationResult { IsValid = false, Error = "Key is empty" };
+
+        try
+        {
+            var request = new { key = key.Trim(), organization_id = OrganizationId };
+            var response = await _http.PostAsJsonAsync(ValidateUrl, request, ct);
+
+            if (!response.IsSuccessStatusCode)
+            {
+                var body = await response.Content.ReadAsStringAsync(ct);
+                return new LicenseValidationResult
+                {
+                    IsValid = false,
+                    Error = $"Validation failed ({(int)response.StatusCode}): {body}"
+                };
+            }
+
+            var result = await response.Content.ReadFromJsonAsync<PolarValidateResponse>(ct);
+            if (result == null)
+                return new LicenseValidationResult { IsValid = false, Error = "Empty response from Polar" };
+
+            var status = result.Status?.ToLowerInvariant();
+            return new LicenseValidationResult
+            {
+                IsValid = status == "granted",
+                Status = status ?? "unknown",
+                ExpiresAt = result.ExpiresAt,
+                Error = status == "granted" ? null : $"License status: {status}"
+            };
+        }
+        catch (TaskCanceledException)
+        {
+            return new LicenseValidationResult { IsValid = false, Error = "Validation timed out" };
+        }
+        catch (HttpRequestException ex)
+        {
+            return new LicenseValidationResult { IsValid = false, Error = $"Network error: {ex.Message}" };
+        }
+        catch (Exception ex)
+        {
+            return new LicenseValidationResult { IsValid = false, Error = $"Unexpected error: {ex.Message}" };
+        }
+    }
+
+    private sealed class PolarValidateResponse
+    {
+        [JsonPropertyName("status")]
+        public string? Status { get; set; }
+
+        [JsonPropertyName("expires_at")]
+        public DateTime? ExpiresAt { get; set; }
+    }
+}
+
+public sealed class LicenseValidationResult
+{
+    public bool IsValid { get; set; }
+    public string? Status { get; set; }
+    public DateTime? ExpiresAt { get; set; }
+    public string? Error { get; set; }
+}