Add Custom Formula Item Templates with AI generation and wizard integration

Introduces per-company reusable NCalc2 pricing formula templates for complex
fabricated items (roof curbs, enclosures, welded frames). Templates support
two output modes — FixedRate (formula yields a dollar amount) and SurfaceAreaSqFt
(formula yields sq ft fed into the standard coating engine). Includes:

- CustomItemTemplate entity, migration (AddCustomItemTemplates), IUnitOfWork repo
- IsCustomFormulaItem / CustomItemTemplateId / FormulaFieldValuesJson flags on
  QuoteItem, JobItem, CreateQuoteItemDto; mapped in all 3 JobItemAssemblyService
  overloads and all existingItemsData JSON projections + pageMeta blocks
- ICustomFormulaAiService / CustomFormulaAiService: Claude-powered formula
  generator (natural language + optional diagram image) and NCalc2 evaluator
- CompanySettings CRUD endpoints: GetCustomItemTemplates, Create/Update/Delete,
  UploadTemplateDiagram, TemplateDiagram (blob serve), EvaluateFormula, GenerateFormulaFromAi
- Company Settings "Custom Formulas" tab + cfModal + company-settings-custom-formulas.js
- item-wizard.js: formula item type card, renderFormulaFields, wzFormulaRecalc
  (live evaluate via POST), collectStep2 formula branch, buildCardHtml / emitHiddenFields
- Formula badge in Quotes/Details and Jobs/Details; AI badge gap fixed in Jobs/Details
- Help article (CustomFormulaTemplates.cshtml), Help Index card, HelpController action,
  HelpKnowledgeBase entry; 225/225 unit tests passing

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Infrastructure/Data/ApplicationDbContext.cs

@@ -374,6 +374,10 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IDataPro
     /// <summary>Customer self-service intake sessions (walk-in tablet or remote email link); tenant-filtered with soft delete.</summary>
     public DbSet<KioskSession> KioskSessions { get; set; }
 
+    // Custom Formula Templates
+    /// <summary>Per-company reusable NCalc pricing formula templates; tenant-filtered with soft delete.</summary>
+    public DbSet<CustomItemTemplate> CustomItemTemplates { get; set; }
+
     /// <summary>
     /// Platform-wide audit log capturing who changed what and when, across all tenants.
     /// No global query filter — SuperAdmin controllers query this directly.

src/PowderCoating.Infrastructure/Migrations/20260523153055_AddCustomItemTemplates.cs

@@ -0,0 +1,197 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace PowderCoating.Infrastructure.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddCustomItemTemplates : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<int>(
+                name: "CustomItemTemplateId",
+                table: "QuoteItems",
+                type: "int",
+                nullable: true);
+
+            migrationBuilder.AddColumn<string>(
+                name: "FormulaFieldValuesJson",
+                table: "QuoteItems",
+                type: "nvarchar(max)",
+                nullable: true);
+
+            migrationBuilder.AddColumn<bool>(
+                name: "IsCustomFormulaItem",
+                table: "QuoteItems",
+                type: "bit",
+                nullable: false,
+                defaultValue: false);
+
+            migrationBuilder.AddColumn<int>(
+                name: "CustomItemTemplateId",
+                table: "JobItems",
+                type: "int",
+                nullable: true);
+
+            migrationBuilder.AddColumn<string>(
+                name: "FormulaFieldValuesJson",
+                table: "JobItems",
+                type: "nvarchar(max)",
+                nullable: true);
+
+            migrationBuilder.AddColumn<bool>(
+                name: "IsCustomFormulaItem",
+                table: "JobItems",
+                type: "bit",
+                nullable: false,
+                defaultValue: false);
+
+            migrationBuilder.CreateTable(
+                name: "CustomItemTemplates",
+                columns: table => new
+                {
+                    Id = table.Column<int>(type: "int", nullable: false)
+                        .Annotation("SqlServer:Identity", "1, 1"),
+                    Name = table.Column<string>(type: "nvarchar(max)", nullable: false),
+                    Description = table.Column<string>(type: "nvarchar(max)", nullable: true),
+                    OutputMode = table.Column<string>(type: "nvarchar(max)", nullable: false),
+                    FieldsJson = table.Column<string>(type: "nvarchar(max)", nullable: false),
+                    Formula = table.Column<string>(type: "nvarchar(max)", nullable: false),
+                    DefaultRate = table.Column<decimal>(type: "decimal(18,2)", nullable: true),
+                    RateLabel = table.Column<string>(type: "nvarchar(max)", nullable: true),
+                    Notes = table.Column<string>(type: "nvarchar(max)", nullable: true),
+                    DisplayOrder = table.Column<int>(type: "int", nullable: false),
+                    IsActive = table.Column<bool>(type: "bit", nullable: false),
+                    DiagramImagePath = table.Column<string>(type: "nvarchar(max)", nullable: true),
+                    CompanyId = table.Column<int>(type: "int", nullable: false),
+                    CreatedAt = table.Column<DateTime>(type: "datetime2", nullable: false),
+                    UpdatedAt = table.Column<DateTime>(type: "datetime2", nullable: true),
+                    CreatedBy = table.Column<string>(type: "nvarchar(max)", nullable: true),
+                    UpdatedBy = table.Column<string>(type: "nvarchar(max)", nullable: true),
+                    IsDeleted = table.Column<bool>(type: "bit", nullable: false),
+                    DeletedAt = table.Column<DateTime>(type: "datetime2", nullable: true),
+                    DeletedBy = table.Column<string>(type: "nvarchar(max)", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_CustomItemTemplates", x => x.Id);
+                });
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 1,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 23, 15, 30, 51, 760, DateTimeKind.Utc).AddTicks(9869));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 2,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 23, 15, 30, 51, 760, DateTimeKind.Utc).AddTicks(9876));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 3,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 23, 15, 30, 51, 760, DateTimeKind.Utc).AddTicks(9878));
+
+            migrationBuilder.CreateIndex(
+                name: "IX_QuoteItems_CustomItemTemplateId",
+                table: "QuoteItems",
+                column: "CustomItemTemplateId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_JobItems_CustomItemTemplateId",
+                table: "JobItems",
+                column: "CustomItemTemplateId");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_JobItems_CustomItemTemplates_CustomItemTemplateId",
+                table: "JobItems",
+                column: "CustomItemTemplateId",
+                principalTable: "CustomItemTemplates",
+                principalColumn: "Id");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_QuoteItems_CustomItemTemplates_CustomItemTemplateId",
+                table: "QuoteItems",
+                column: "CustomItemTemplateId",
+                principalTable: "CustomItemTemplates",
+                principalColumn: "Id");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_JobItems_CustomItemTemplates_CustomItemTemplateId",
+                table: "JobItems");
+
+            migrationBuilder.DropForeignKey(
+                name: "FK_QuoteItems_CustomItemTemplates_CustomItemTemplateId",
+                table: "QuoteItems");
+
+            migrationBuilder.DropTable(
+                name: "CustomItemTemplates");
+
+            migrationBuilder.DropIndex(
+                name: "IX_QuoteItems_CustomItemTemplateId",
+                table: "QuoteItems");
+
+            migrationBuilder.DropIndex(
+                name: "IX_JobItems_CustomItemTemplateId",
+                table: "JobItems");
+
+            migrationBuilder.DropColumn(
+                name: "CustomItemTemplateId",
+                table: "QuoteItems");
+
+            migrationBuilder.DropColumn(
+                name: "FormulaFieldValuesJson",
+                table: "QuoteItems");
+
+            migrationBuilder.DropColumn(
+                name: "IsCustomFormulaItem",
+                table: "QuoteItems");
+
+            migrationBuilder.DropColumn(
+                name: "CustomItemTemplateId",
+                table: "JobItems");
+
+            migrationBuilder.DropColumn(
+                name: "FormulaFieldValuesJson",
+                table: "JobItems");
+
+            migrationBuilder.DropColumn(
+                name: "IsCustomFormulaItem",
+                table: "JobItems");
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 1,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 23, 13, 51, 6, 293, DateTimeKind.Utc).AddTicks(4300));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 2,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 23, 13, 51, 6, 293, DateTimeKind.Utc).AddTicks(4313));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 3,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 23, 13, 51, 6, 293, DateTimeKind.Utc).AddTicks(4315));
+        }
+    }
+}

src/PowderCoating.Infrastructure/Migrations/ApplicationDbContextModelSnapshot.cs

@@ -2650,6 +2650,80 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.ToTable("CreditMemoApplications");
                 });
 
+            modelBuilder.Entity("PowderCoating.Core.Entities.CustomItemTemplate", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("int");
+
+                    SqlServerPropertyBuilderExtensions.UseIdentityColumn(b.Property<int>("Id"));
+
+                    b.Property<int>("CompanyId")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("datetime2");
+
+                    b.Property<string>("CreatedBy")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<decimal?>("DefaultRate")
+                        .HasColumnType("decimal(18,2)");
+
+                    b.Property<DateTime?>("DeletedAt")
+                        .HasColumnType("datetime2");
+
+                    b.Property<string>("DeletedBy")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("DiagramImagePath")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<int>("DisplayOrder")
+                        .HasColumnType("int");
+
+                    b.Property<string>("FieldsJson")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("Formula")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<bool>("IsActive")
+                        .HasColumnType("bit");
+
+                    b.Property<bool>("IsDeleted")
+                        .HasColumnType("bit");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("Notes")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("OutputMode")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("RateLabel")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<DateTime?>("UpdatedAt")
+                        .HasColumnType("datetime2");
+
+                    b.Property<string>("UpdatedBy")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("CustomItemTemplates");
+                });
+
             modelBuilder.Entity("PowderCoating.Core.Entities.Customer", b =>
                 {
                     b.Property<int>("Id")
@@ -4473,6 +4547,9 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.Property<string>("CreatedBy")
                         .HasColumnType("nvarchar(max)");
 
+                    b.Property<int?>("CustomItemTemplateId")
+                        .HasColumnType("int");
+
                     b.Property<DateTime?>("DeletedAt")
                         .HasColumnType("datetime2");
 
@@ -4489,12 +4566,18 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.Property<string>("Finish")
                         .HasColumnType("nvarchar(max)");
 
+                    b.Property<string>("FormulaFieldValuesJson")
+                        .HasColumnType("nvarchar(max)");
+
                     b.Property<bool>("IncludePrepCost")
                         .HasColumnType("bit");
 
                     b.Property<bool>("IsAiItem")
                         .HasColumnType("bit");
 
+                    b.Property<bool>("IsCustomFormulaItem")
+                        .HasColumnType("bit");
+
                     b.Property<bool>("IsDeleted")
                         .HasColumnType("bit");
 
@@ -4558,6 +4641,8 @@ namespace PowderCoating.Infrastructure.Migrations
 
                     b.HasIndex("CatalogItemId");
 
+                    b.HasIndex("CustomItemTemplateId");
+
                     b.HasIndex("JobId")
                         .HasDatabaseName("IX_JobItems_JobId");
 
@@ -6711,7 +6796,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 1,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 5, 23, 13, 51, 6, 293, DateTimeKind.Utc).AddTicks(4300),
+                            CreatedAt = new DateTime(2026, 5, 23, 15, 30, 51, 760, DateTimeKind.Utc).AddTicks(9869),
                             Description = "Standard pricing for regular customers",
                             DiscountPercent = 0m,
                             IsActive = true,
@@ -6722,7 +6807,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 2,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 5, 23, 13, 51, 6, 293, DateTimeKind.Utc).AddTicks(4313),
+                            CreatedAt = new DateTime(2026, 5, 23, 15, 30, 51, 760, DateTimeKind.Utc).AddTicks(9876),
                             Description = "5% discount for preferred customers",
                             DiscountPercent = 5m,
                             IsActive = true,
@@ -6733,7 +6818,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 3,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 5, 23, 13, 51, 6, 293, DateTimeKind.Utc).AddTicks(4315),
+                            CreatedAt = new DateTime(2026, 5, 23, 15, 30, 51, 760, DateTimeKind.Utc).AddTicks(9878),
                             Description = "10% discount for premium customers",
                             DiscountPercent = 10m,
                             IsActive = true,
@@ -7260,6 +7345,9 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.Property<string>("CreatedBy")
                         .HasColumnType("nvarchar(max)");
 
+                    b.Property<int?>("CustomItemTemplateId")
+                        .HasColumnType("int");
+
                     b.Property<DateTime?>("DeletedAt")
                         .HasColumnType("datetime2");
 
@@ -7273,12 +7361,18 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.Property<int>("EstimatedMinutes")
                         .HasColumnType("int");
 
+                    b.Property<string>("FormulaFieldValuesJson")
+                        .HasColumnType("nvarchar(max)");
+
                     b.Property<bool>("IncludePrepCost")
                         .HasColumnType("bit");
 
                     b.Property<bool>("IsAiItem")
                         .HasColumnType("bit");
 
+                    b.Property<bool>("IsCustomFormulaItem")
+                        .HasColumnType("bit");
+
                     b.Property<bool>("IsDeleted")
                         .HasColumnType("bit");
 
@@ -7348,6 +7442,8 @@ namespace PowderCoating.Infrastructure.Migrations
 
                     b.HasIndex("CatalogItemId");
 
+                    b.HasIndex("CustomItemTemplateId");
+
                     b.HasIndex("QuoteId")
                         .HasDatabaseName("IX_QuoteItems_QuoteId");
 
@@ -9512,6 +9608,10 @@ namespace PowderCoating.Infrastructure.Migrations
                         .HasForeignKey("CatalogItemId")
                         .OnDelete(DeleteBehavior.SetNull);
 
+                    b.HasOne("PowderCoating.Core.Entities.CustomItemTemplate", "CustomItemTemplate")
+                        .WithMany()
+                        .HasForeignKey("CustomItemTemplateId");
+
                     b.HasOne("PowderCoating.Core.Entities.Job", "Job")
                         .WithMany("JobItems")
                         .HasForeignKey("JobId")
@@ -9522,6 +9622,8 @@ namespace PowderCoating.Infrastructure.Migrations
 
                     b.Navigation("CatalogItem");
 
+                    b.Navigation("CustomItemTemplate");
+
                     b.Navigation("Job");
                 });
 
@@ -10131,6 +10233,10 @@ namespace PowderCoating.Infrastructure.Migrations
                         .WithMany()
                         .HasForeignKey("CatalogItemId");
 
+                    b.HasOne("PowderCoating.Core.Entities.CustomItemTemplate", "CustomItemTemplate")
+                        .WithMany()
+                        .HasForeignKey("CustomItemTemplateId");
+
                     b.HasOne("PowderCoating.Core.Entities.Quote", "Quote")
                         .WithMany("QuoteItems")
                         .HasForeignKey("QuoteId")
@@ -10141,6 +10247,8 @@ namespace PowderCoating.Infrastructure.Migrations
 
                     b.Navigation("CatalogItem");
 
+                    b.Navigation("CustomItemTemplate");
+
                     b.Navigation("Quote");
                 });
 

src/PowderCoating.Infrastructure/PowderCoating.Infrastructure.csproj

@@ -21,6 +21,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
+    <PackageReference Include="NCalc2" Version="2.1.0" />
     <PackageReference Include="SendGrid" Version="9.29.3" />
     <PackageReference Include="SixLabors.ImageSharp" Version="3.1.12" />
     <PackageReference Include="Stripe.net" Version="50.4.1" />

src/PowderCoating.Infrastructure/Repositories/UnitOfWork.cs

@@ -123,6 +123,9 @@ public class UnitOfWork : IUnitOfWork
     // Customer Intake Kiosk
     private IRepository<KioskSession>? _kioskSessions;
 
+    // Custom Formula Templates
+    private IRepository<CustomItemTemplate>? _customItemTemplates;
+
     // Purchase Orders
     private IPurchaseOrderRepository? _purchaseOrders;
     private IRepository<PurchaseOrderItem>? _purchaseOrderItems;
@@ -457,6 +460,10 @@ public class UnitOfWork : IUnitOfWork
     public IRepository<KioskSession> KioskSessions =>
         _kioskSessions ??= new Repository<KioskSession>(_context);
 
+    /// <summary>Repository for <see cref="CustomItemTemplate"/> per-company reusable NCalc pricing formula templates; tenant-filtered with soft delete.</summary>
+    public IRepository<CustomItemTemplate> CustomItemTemplates =>
+        _customItemTemplates ??= new Repository<CustomItemTemplate>(_context);
+
     // Job Templates
     /// <summary>Repository for <see cref="JobTemplate"/> reusable job blueprints; tenant-filtered with soft delete.</summary>
     public IJobTemplateRepository JobTemplates =>

src/PowderCoating.Infrastructure/Services/CustomFormulaAiService.cs

@@ -0,0 +1,197 @@
+using System.Text;
+using System.Text.Json;
+using NCalc2;
+using Anthropic.SDK;
+using Anthropic.SDK.Messaging;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Logging;
+using PowderCoating.Application.DTOs.Company;
+using PowderCoating.Application.Interfaces;
+
+namespace PowderCoating.Infrastructure.Services;
+
+/// <summary>
+/// Generates NCalc pricing formula templates from natural-language descriptions using
+/// Claude Sonnet. Accepts an optional diagram image so the model can see the physical
+/// shape being estimated. The model returns a structured JSON object containing the
+/// field list, NCalc expression, output mode, and verification inputs; the service
+/// parses and returns it as a <see cref="GenerateFormulaFromAiResponse"/>.
+/// </summary>
+public class CustomFormulaAiService : ICustomFormulaAiService
+{
+    private readonly IConfiguration _config;
+    private readonly ILogger<CustomFormulaAiService> _logger;
+
+    private const string SystemPrompt = @"You are an expert pricing formula engineer for a powder coating business.
+Your job is to generate NCalc expressions that calculate either a fixed price or a surface area
+from user-supplied field values. NCalc supports standard math operators (+, -, *, /, %, Pow()),
+comparison operators, and the Abs(), Round(), Max(), Min() built-in functions.
+
+The user will describe a custom fabricated item (e.g., 'Roof curb', 'Electrical enclosure',
+'Tubular frame') and you must produce a pricing formula template.
+
+Respond ONLY with a valid JSON object matching this exact schema — no markdown, no explanation:
+
+{
+  ""name"": ""string — short template name (e.g. 'Roof Curb', 'Electrical Enclosure')"",
+  ""outputMode"": ""FixedRate"" | ""SurfaceAreaSqFt"",
+  ""fields"": [
+    {
+      ""name"": ""snake_case_variable_name"",
+      ""label"": ""Human-readable label"",
+      ""unit"": ""in / ft / mm / cm / qty / lbs — or empty string"",
+      ""defaultValue"": number
+    }
+  ],
+  ""formula"": ""NCalc expression using field name variables and optionally 'rate'"",
+  ""defaultRate"": number or null,
+  ""rateLabel"": ""string label for the rate field, e.g. '$/sq ft' — null if no rate"",
+  ""reasoning"": ""1-2 sentences explaining how the formula was derived"",
+  ""verificationInputs"": { ""variable_name"": number },
+  ""verificationResult"": number
+}
+
+Rules:
+- Use FixedRate when the formula directly calculates a dollar amount (e.g. surface area × rate per sqft)
+- Use SurfaceAreaSqFt when the formula calculates square footage and the standard pricing engine handles the rest
+- Always include a 'rate' variable when outputMode is FixedRate and the price scales with dimensions
+- Field names must be valid NCalc identifiers (letters, digits, underscores; no spaces or hyphens)
+- verificationInputs and verificationResult must use the exact field names and formula you generated
+- Surface area formulas for box shapes: 2*(L*W + L*H + W*H) where L/W/H are in the same unit; convert to sqft if needed
+- For inch inputs convert to sqft: divide by 144 (sqin→sqft) or use /12 per side before multiplying
+";
+
+    public CustomFormulaAiService(IConfiguration config, ILogger<CustomFormulaAiService> logger)
+    {
+        _config = config;
+        _logger = logger;
+    }
+
+    /// <inheritdoc />
+    public async Task<GenerateFormulaFromAiResponse> GenerateFormulaAsync(
+        GenerateFormulaFromAiRequest request,
+        byte[]? imageBytes = null,
+        string? imageContentType = null)
+    {
+        var apiKey = _config["AI:Anthropic:ApiKey"];
+        if (string.IsNullOrWhiteSpace(apiKey) || apiKey.StartsWith("your-"))
+        {
+            return new GenerateFormulaFromAiResponse
+            {
+                Success = false,
+                Error = "Anthropic API key is not configured. Add AI:Anthropic:ApiKey to appsettings.json."
+            };
+        }
+
+        try
+        {
+            var client = new AnthropicClient(apiKey);
+
+            var userContent = new List<ContentBase>();
+
+            if (imageBytes is { Length: > 0 } && !string.IsNullOrWhiteSpace(imageContentType))
+            {
+                userContent.Add(new ImageContent
+                {
+                    Source = new ImageSource
+                    {
+                        MediaType = imageContentType,
+                        Data = Convert.ToBase64String(imageBytes)
+                    }
+                });
+            }
+
+            userContent.Add(new TextContent { Text = request.Description });
+
+            var messages = new List<Message>
+            {
+                new() { Role = RoleType.User, Content = userContent }
+            };
+
+            var response = await client.Messages.GetClaudeMessageAsync(new MessageParameters
+            {
+                Model = "claude-sonnet-4-6",
+                MaxTokens = 1024,
+                SystemMessage = SystemPrompt,
+                Messages = messages
+            });
+
+            var rawJson = response.Message.ToString().Trim();
+
+            // Strip markdown code fences if the model adds them
+            if (rawJson.StartsWith("```"))
+            {
+                var start = rawJson.IndexOf('\n') + 1;
+                var end = rawJson.LastIndexOf("```");
+                if (end > start) rawJson = rawJson[start..end].Trim();
+            }
+
+            using var doc = JsonDocument.Parse(rawJson);
+            var root = doc.RootElement;
+
+            var fieldsJson = root.TryGetProperty("fields", out var fieldsEl)
+                ? fieldsEl.GetRawText()
+                : "[]";
+
+            decimal? defaultRate = null;
+            if (root.TryGetProperty("defaultRate", out var rateEl) && rateEl.ValueKind == JsonValueKind.Number)
+                defaultRate = rateEl.GetDecimal();
+
+            decimal? verificationResult = null;
+            if (root.TryGetProperty("verificationResult", out var vrEl) && vrEl.ValueKind == JsonValueKind.Number)
+                verificationResult = vrEl.GetDecimal();
+
+            string? verificationInputs = null;
+            if (root.TryGetProperty("verificationInputs", out var viEl))
+                verificationInputs = viEl.GetRawText();
+
+            return new GenerateFormulaFromAiResponse
+            {
+                Success = true,
+                Name = root.TryGetProperty("name", out var nameEl) ? nameEl.GetString() : null,
+                OutputMode = root.TryGetProperty("outputMode", out var omEl) ? omEl.GetString() : "FixedRate",
+                FieldsJson = fieldsJson,
+                Formula = root.TryGetProperty("formula", out var fEl) ? fEl.GetString() : null,
+                DefaultRate = defaultRate,
+                RateLabel = root.TryGetProperty("rateLabel", out var rlEl) ? rlEl.GetString() : null,
+                Reasoning = root.TryGetProperty("reasoning", out var reEl) ? reEl.GetString() : null,
+                VerificationResult = verificationResult,
+                VerificationInputs = verificationInputs
+            };
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "CustomFormulaAiService.GenerateFormulaAsync failed");
+            return new GenerateFormulaFromAiResponse { Success = false, Error = ex.Message };
+        }
+    }
+
+    /// <inheritdoc />
+    public EvaluateFormulaResponse EvaluateFormula(EvaluateFormulaRequest request)
+    {
+        if (string.IsNullOrWhiteSpace(request?.Formula))
+            return new EvaluateFormulaResponse { Success = false, Error = "Formula is required." };
+
+        try
+        {
+            var variables = JsonSerializer.Deserialize<Dictionary<string, JsonElement>>(
+                request.VariablesJson ?? "{}") ?? new();
+
+            var expr = new Expression(request.Formula);
+            foreach (var kv in variables)
+            {
+                expr.Parameters[kv.Key] = kv.Value.ValueKind == JsonValueKind.Number
+                    ? (object)kv.Value.GetDecimal()
+                    : (object)(kv.Value.GetString() ?? "");
+            }
+
+            var result = expr.Evaluate();
+            var decResult = Convert.ToDecimal(result);
+            return new EvaluateFormulaResponse { Success = true, Result = Math.Round(decResult, 4) };
+        }
+        catch (Exception ex)
+        {
+            return new EvaluateFormulaResponse { Success = false, Error = ex.Message };
+        }
+    }
+}