Add 6 month default and max MCP token expiry

EssentialCSharp.Web.Tests/McpApiTokenServiceTests.cs

@@ -0,0 +1,54 @@
+using EssentialCSharp.Web.Services;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace EssentialCSharp.Web.Tests;
+
+[NotInParallel("McpTests")]
+[ClassDataSource<WebApplicationFactory>(Shared = SharedType.PerClass)]
+public class McpApiTokenServiceTests(WebApplicationFactory factory)
+{
+    [Test]
+    public async Task CreateTokenAsync_WithoutExpiry_UsesSixMonthDefault()
+    {
+        string userId = await McpTestHelper.CreateUserAsync(factory, "mcp-default-expiry");
+
+        using var scope = factory.Services.CreateScope();
+        var tokenService = scope.ServiceProvider.GetRequiredService<McpApiTokenService>();
+
+        (_, var entity) = await tokenService.CreateTokenAsync(userId, "default-expiry");
+
+        await Assert.That(entity.ExpiresAt).IsNotNull();
+        await Assert.That(entity.ExpiresAt!.Value)
+            .IsEqualTo(McpApiTokenService.GetDefaultExpirationUtc(entity.CreatedAt));
+    }
+
+    [Test]
+    public async Task CreateTokenAsync_WithExpiryWithinSixMonths_UsesRequestedExpiry()
+    {
+        string userId = await McpTestHelper.CreateUserAsync(factory, "mcp-custom-expiry");
+
+        using var scope = factory.Services.CreateScope();
+        var tokenService = scope.ServiceProvider.GetRequiredService<McpApiTokenService>();
+        DateTime requestedExpiry = DateTime.UtcNow.AddMonths(3);
+
+        (_, var entity) = await tokenService.CreateTokenAsync(userId, "custom-expiry", requestedExpiry);
+
+        await Assert.That(entity.ExpiresAt).IsNotNull();
+        await Assert.That(entity.ExpiresAt!.Value).IsEqualTo(requestedExpiry);
+    }
+
+    [Test]
+    public async Task CreateTokenAsync_WithExpiryBeyondSixMonths_Throws()
+    {
+        string userId = await McpTestHelper.CreateUserAsync(factory, "mcp-max-expiry");
+
+        using var scope = factory.Services.CreateScope();
+        var tokenService = scope.ServiceProvider.GetRequiredService<McpApiTokenService>();
+        DateTime requestedExpiry = McpApiTokenService.GetDefaultExpirationUtc(DateTime.UtcNow).AddDays(1);
+
+        await Assert.That(() => tokenService.CreateTokenAsync(userId, "too-long", requestedExpiry))
+            .Throws<ArgumentOutOfRangeException>()
+            .WithMessageContaining("6 months");
+    }
+}

EssentialCSharp.Web/Areas/Identity/Pages/Account/Manage/McpAccess.cshtml

@@ -58,10 +58,10 @@
                     <span asp-validation-for="TokenName" class="text-danger"></span>
                 </div>
                 <div class="mb-3">
-                    <label asp-for="ExpiresOn" class="form-label">Expiry Date <span class="text-muted">(optional)</span></label>
-                    <input asp-for="ExpiresOn" type="date" class="form-control" />
+                    <label asp-for="ExpiresOn" class="form-label">Expiry Date</label>
+                    <input asp-for="ExpiresOn" type="date" class="form-control" max="@Model.MaxExpiresOn.ToString("yyyy-MM-dd")" />
                     <span asp-validation-for="ExpiresOn" class="text-danger"></span>
-                    <div class="form-text">Leave blank for a non-expiring token. The token expires at end of day (23:59:59) UTC on the selected date.</div>
+                    <div class="form-text">MCP tokens default to 6 months and cannot exceed 6 months from today. The token expires at end of day (23:59:59) UTC on the selected date.</div>
                 </div>
                 <button type="submit" class="btn btn-primary">Create Token</button>
             </form>

EssentialCSharp.Web/Areas/Identity/Pages/Account/Manage/McpAccess.cshtml.cs

@@ -21,6 +21,8 @@ public class McpAccessModel(
 
     public List<McpApiToken> UserTokens { get; private set; } = [];
 
+    public DateOnly MaxExpiresOn { get; private set; }
+
     [BindProperty]
     [StringLength(256, ErrorMessage = "Token name must be 256 characters or fewer.")]
     public string TokenName { get; set; } = "My Token";
@@ -31,6 +33,8 @@ public class McpAccessModel(
     public async Task<IActionResult> OnGetAsync()
     {
         DisableCaching();
+        InitializeExpiryBounds();
+        ApplyDefaultExpiryIfMissing();
         string? userId = userManager.GetUserId(User);
         if (userId is null) return Challenge();
         UserTokens = await tokenService.GetUserTokensAsync(userId);
@@ -40,14 +44,21 @@ public async Task<IActionResult> OnGetAsync()
     public async Task<IActionResult> OnPostCreateAsync()
     {
         DisableCaching();
+        InitializeExpiryBounds();
+        ApplyDefaultExpiryIfMissing();
         string? userId = userManager.GetUserId(User);
         if (userId is null) return Challenge();
 
         if (string.IsNullOrWhiteSpace(TokenName))
             ModelState.AddModelError(nameof(TokenName), "Token name is required.");
 
-        if (ExpiresOn.HasValue && ExpiresOn.Value < DateOnly.FromDateTime(DateTime.UtcNow))
-            ModelState.AddModelError(nameof(ExpiresOn), "Expiry date must be today or in the future.");
+        if (ExpiresOn.HasValue)
+        {
+            if (ExpiresOn.Value < DateOnly.FromDateTime(DateTime.UtcNow))
+                ModelState.AddModelError(nameof(ExpiresOn), "Expiry date must be today or in the future.");
+            if (ExpiresOn.Value > MaxExpiresOn)
+                ModelState.AddModelError(nameof(ExpiresOn), McpApiTokenService.MaxExpiryValidationMessage);
+        }
 
         if (!ModelState.IsValid)
         {
@@ -85,4 +96,14 @@ private void DisableCaching()
         Response.Headers.Pragma = "no-cache";
         Response.Headers.Expires = "0";
     }
+
+    private void InitializeExpiryBounds()
+    {
+        MaxExpiresOn = McpApiTokenService.GetDefaultExpiryDate();
+    }
+
+    private void ApplyDefaultExpiryIfMissing()
+    {
+        ExpiresOn ??= MaxExpiresOn;
+    }
 }

EssentialCSharp.Web/Controllers/McpTokenController.cs

@@ -27,10 +27,13 @@ public async Task<IActionResult> CreateToken(
             return BadRequest(new { Error = "Token name must be 256 characters or fewer." });
 
         DateTime? expiresAt = null;
+        DateOnly maxExpiresOn = McpApiTokenService.GetDefaultExpiryDate();
         if (request?.ExpiresOn is DateOnly expiresOn)
         {
             if (expiresOn < DateOnly.FromDateTime(DateTime.UtcNow))
                 return BadRequest(new { Error = "ExpiresOn must be today or in the future." });
+            if (expiresOn > maxExpiresOn)
+                return BadRequest(new { Error = McpApiTokenService.MaxExpiryValidationMessage });
             // Convert date-only boundary to end-of-day UTC instant before persisting
             expiresAt = expiresOn.ToDateTime(TimeOnly.MaxValue, DateTimeKind.Utc);
         }

EssentialCSharp.Web/Services/McpApiTokenService.cs

@@ -9,8 +9,17 @@ namespace EssentialCSharp.Web.Services;
 
 public class McpApiTokenService(EssentialCSharpWebContext db)
 {
+    public const int DefaultLifetimeMonths = 6;
+    public const string MaxExpiryValidationMessage = "MCP tokens can expire at most 6 months from today.";
+
     public sealed record ResolvedMcpApiToken(Guid TokenId, string UserId);
 
+    public static DateOnly GetDefaultExpiryDate(DateTime? referenceTimeUtc = null)
+        => DateOnly.FromDateTime(referenceTimeUtc ?? DateTime.UtcNow).AddMonths(DefaultLifetimeMonths);
+
+    public static DateTime GetDefaultExpirationUtc(DateTime? referenceTimeUtc = null)
+        => GetDefaultExpiryDate(referenceTimeUtc).ToDateTime(TimeOnly.MaxValue, DateTimeKind.Utc);
+
     /// <summary>Returns SHA-256 hash of the raw token as a byte array (varbinary(32)).</summary>
     public static byte[] HashToken(string rawToken)
         => SHA256.HashData(Encoding.UTF8.GetBytes(rawToken));
@@ -30,19 +39,34 @@ public static string GenerateRawToken()
         CancellationToken cancellationToken = default)
     {
         string raw = GenerateRawToken();
+        DateTime createdAt = DateTime.UtcNow;
+        DateTime effectiveExpiration = ResolveExpiration(expiresAt, createdAt);
+
         var entity = new McpApiToken
         {
             UserId = userId,
             Name = name,
             TokenHash = HashToken(raw),
-            CreatedAt = DateTime.UtcNow,
-            ExpiresAt = expiresAt,
+            CreatedAt = createdAt,
+            ExpiresAt = effectiveExpiration,
         };
         db.McpApiTokens.Add(entity);
         await db.SaveChangesAsync(cancellationToken);
         return (raw, entity);
     }
 
+    private static DateTime ResolveExpiration(DateTime? requestedExpirationUtc, DateTime createdAtUtc)
+    {
+        DateTime maxExpiration = GetDefaultExpirationUtc(createdAtUtc);
+        if (requestedExpirationUtc is null)
+            return maxExpiration;
+
+        if (requestedExpirationUtc > maxExpiration)
+            throw new ArgumentOutOfRangeException(nameof(requestedExpirationUtc), MaxExpiryValidationMessage);
+
+        return requestedExpirationUtc.Value;
+    }
+
     /// <summary>
     /// Revokes a token by ID. Validates ownership to prevent cross-user revocation.
     /// Returns false if token not found or user doesn't own it.

EssentialCSharp.Web/Views/McpSetup/Index.cshtml

@@ -52,7 +52,8 @@
         <h5>Step 2 — Generate a token</h5>
         <p>
             Go to <a href="/Identity/Account/Manage/McpAccess">MCP Access</a> under your account settings.
-            Enter a name for the token (e.g. "VS Code"), choose an optional expiry date, and click
+            Enter a name for the token (e.g. "VS Code"), keep the default 6-month expiry or choose an earlier date,
+            and click
             <strong>Create Token</strong>. Copy the token — it won't be shown again.
         </p>