feat: enforce account usage limits

JobTrackerApi/Controllers/AiWorkspaceController.cs

@@ -4,6 +4,7 @@ using JobTrackerApi.Services;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Identity;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
 
 namespace JobTrackerApi.Controllers;
 
@@ -17,12 +18,14 @@ public sealed class AiWorkspaceController : ControllerBase
     private readonly UserManager<ApplicationUser> _users;
     private readonly IAiWorkspaceService _workspace;
     private readonly IConfiguration _config;
+    private readonly JobTrackerApi.Data.JobTrackerContext? _db;
 
-    public AiWorkspaceController(UserManager<ApplicationUser> users, IAiWorkspaceService workspace, IConfiguration config)
+    public AiWorkspaceController(UserManager<ApplicationUser> users, IAiWorkspaceService workspace, IConfiguration config, JobTrackerApi.Data.JobTrackerContext? db = null)
     {
         _users = users;
         _workspace = workspace;
         _config = config;
+        _db = db;
     }
 
     public sealed record GenerateRequest(string Module, string? Mode, string? ExtraContext);
@@ -38,6 +41,15 @@ public sealed class AiWorkspaceController : ControllerBase
         if (user is null) return Unauthorized();
         if (string.IsNullOrWhiteSpace(request?.Module)) return BadRequest("Choose an AI module.");
 
+        if (_db is not null)
+        {
+            var roles = await _users.GetRolesAsync(user);
+            var limit = AccountPlans.ForRoles(roles).MonthlyAiCalls;
+            var monthStart = new DateTimeOffset(DateTime.UtcNow.Year, DateTime.UtcNow.Month, 1, 0, 0, 0, TimeSpan.Zero);
+            var used = await _db.AiInteractions.CountAsync(x => x.OwnerUserId == user.Id && x.CreatedAtUtc >= monthStart, ct);
+            if (used >= limit) return StatusCode(StatusCodes.Status429TooManyRequests, $"Monthly AI limit reached ({limit} generations). Upgrade your plan or try again next month.");
+        }
+
         try
         {
             var interaction = await _workspace.GenerateAsync(