Merge dev into master for prod deploy

RecommendedMaintenanceIntervalDays was a non-nullable int with [Range(1,3650)],
so submitting the form without filling it in bound to 0 and failed validation.
Made nullable on the entity, both DTOs, and the one controller callsite that
calls .AddDays() (now uses .Value). Migration applied.

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

src/PowderCoating.Application/DTOs/Equipment/EquipmentDtos.cs

@@ -20,7 +20,7 @@ public class EquipmentDto
     public string StatusDisplay { get; set; } = string.Empty;
     public string? Location { get; set; }
 
-    public int RecommendedMaintenanceIntervalDays { get; set; }
+    public int? RecommendedMaintenanceIntervalDays { get; set; }
     public DateTime? LastMaintenanceDate { get; set; }
     public DateTime? NextScheduledMaintenance { get; set; }
     public int? DaysUntilMaintenance { get; set; }
@@ -101,7 +101,7 @@ public class CreateEquipmentDto
 
     [Range(1, 3650, ErrorMessage = "Maintenance interval must be between 1 and 3650 days")]
     [Display(Name = "Recommended Maintenance Interval (Days)")]
-    public int RecommendedMaintenanceIntervalDays { get; set; }
+    public int? RecommendedMaintenanceIntervalDays { get; set; }
 
     [Display(Name = "Last Maintenance Date")]
     public DateTime? LastMaintenanceDate { get; set; }

src/PowderCoating.Application/DTOs/Vendor/VendorDtos.cs

@@ -125,6 +125,8 @@ public class CreateVendorDto
 
     [Display(Name = "Default Expense Account")]
     public int? DefaultExpenseAccountId { get; set; }
+
+    public List<int> CategoryIds { get; set; } = new();
 }
 
 // ============================================================================
@@ -209,4 +211,6 @@ public class UpdateVendorDto
 
     [Display(Name = "Default Expense Account")]
     public int? DefaultExpenseAccountId { get; set; }
+
+    public List<int> CategoryIds { get; set; } = new();
 }

src/PowderCoating.Core/Entities/Equipment.cs

@@ -19,7 +19,7 @@ public class Equipment : BaseEntity
     public string? Location { get; set; }
     
     // Maintenance Information
-    public int RecommendedMaintenanceIntervalDays { get; set; }
+    public int? RecommendedMaintenanceIntervalDays { get; set; }
     public DateTime? LastMaintenanceDate { get; set; }
     public DateTime? NextScheduledMaintenance { get; set; }
     

src/PowderCoating.Core/Entities/InventoryCategoryLookup.cs

@@ -12,4 +12,5 @@ public class InventoryCategoryLookup : BaseEntity
 
     // Relationships
     public virtual ICollection<InventoryItem> InventoryItems { get; set; } = new List<InventoryItem>();
+    public virtual ICollection<Vendor> Vendors { get; set; } = new List<Vendor>();
 }

src/PowderCoating.Core/Entities/SupportingEntities.cs

@@ -45,6 +45,7 @@ public class Vendor : BaseEntity
     public virtual ICollection<BillPayment> BillPayments { get; set; } = new List<BillPayment>();
     public virtual ICollection<Expense> Expenses { get; set; } = new List<Expense>();
     public virtual Account? DefaultExpenseAccount { get; set; }
+    public virtual ICollection<InventoryCategoryLookup> Categories { get; set; } = new List<InventoryCategoryLookup>();
 }
 
 public class InventoryTransaction : BaseEntity

src/PowderCoating.Infrastructure/Data/ApplicationDbContext.cs

@@ -809,6 +809,15 @@ modelBuilder.Entity<ReworkRecord>().HasQueryFilter(e =>
             .HasForeignKey(s => s.DefaultExpenseAccountId)
             .OnDelete(DeleteBehavior.SetNull);
 
+        // Vendor ↔ InventoryCategoryLookup (many-to-many supply categories)
+        modelBuilder.Entity<Vendor>()
+            .HasMany(v => v.Categories)
+            .WithMany(c => c.Vendors)
+            .UsingEntity<Dictionary<string, object>>(
+                "VendorInventoryCategories",
+                j => j.HasOne<InventoryCategoryLookup>().WithMany().HasForeignKey("InventoryCategoryLookupId"),
+                j => j.HasOne<Vendor>().WithMany().HasForeignKey("VendorId"));
+
         // Bill → APAccount (no cascade to avoid cycles)
         modelBuilder.Entity<Bill>()
             .HasOne(b => b.APAccount)

src/PowderCoating.Infrastructure/Migrations/20260523135110_AddVendorCategories.cs

@@ -0,0 +1,93 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace PowderCoating.Infrastructure.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddVendorCategories : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "VendorInventoryCategories",
+                columns: table => new
+                {
+                    InventoryCategoryLookupId = table.Column<int>(type: "int", nullable: false),
+                    VendorId = table.Column<int>(type: "int", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_VendorInventoryCategories", x => new { x.InventoryCategoryLookupId, x.VendorId });
+                    table.ForeignKey(
+                        name: "FK_VendorInventoryCategories_InventoryCategoryLookups_InventoryCategoryLookupId",
+                        column: x => x.InventoryCategoryLookupId,
+                        principalTable: "InventoryCategoryLookups",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "FK_VendorInventoryCategories_Vendors_VendorId",
+                        column: x => x.VendorId,
+                        principalTable: "Vendors",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            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));
+
+            migrationBuilder.CreateIndex(
+                name: "IX_VendorInventoryCategories_VendorId",
+                table: "VendorInventoryCategories",
+                column: "VendorId");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "VendorInventoryCategories");
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 1,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 21, 14, 32, 24, 337, DateTimeKind.Utc).AddTicks(8533));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 2,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 21, 14, 32, 24, 337, DateTimeKind.Utc).AddTicks(8542));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 3,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 21, 14, 32, 24, 337, DateTimeKind.Utc).AddTicks(8543));
+        }
+    }
+}

src/PowderCoating.Infrastructure/Migrations/20260524143607_MakeMaintenanceIntervalNullable.cs

@@ -0,0 +1,79 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace PowderCoating.Infrastructure.Migrations
+{
+    /// <inheritdoc />
+    public partial class MakeMaintenanceIntervalNullable : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AlterColumn<int>(
+                name: "RecommendedMaintenanceIntervalDays",
+                table: "Equipment",
+                type: "int",
+                nullable: true,
+                oldClrType: typeof(int),
+                oldType: "int");
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 1,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 24, 14, 36, 3, 317, DateTimeKind.Utc).AddTicks(8197));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 2,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 24, 14, 36, 3, 317, DateTimeKind.Utc).AddTicks(8203));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 3,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 24, 14, 36, 3, 317, DateTimeKind.Utc).AddTicks(8204));
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AlterColumn<int>(
+                name: "RecommendedMaintenanceIntervalDays",
+                table: "Equipment",
+                type: "int",
+                nullable: false,
+                defaultValue: 0,
+                oldClrType: typeof(int),
+                oldType: "int",
+                oldNullable: true);
+
+            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

@@ -3045,7 +3045,7 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.Property<decimal>("PurchasePrice")
                         .HasColumnType("decimal(18,2)");
 
-                    b.Property<int>("RecommendedMaintenanceIntervalDays")
+                    b.Property<int?>("RecommendedMaintenanceIntervalDays")
                         .HasColumnType("int");
 
                     b.Property<string>("SerialNumber")
@@ -6711,7 +6711,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 1,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 5, 21, 14, 32, 24, 337, DateTimeKind.Utc).AddTicks(8533),
+                            CreatedAt = new DateTime(2026, 5, 24, 14, 36, 3, 317, DateTimeKind.Utc).AddTicks(8197),
                             Description = "Standard pricing for regular customers",
                             DiscountPercent = 0m,
                             IsActive = true,
@@ -6722,7 +6722,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 2,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 5, 21, 14, 32, 24, 337, DateTimeKind.Utc).AddTicks(8542),
+                            CreatedAt = new DateTime(2026, 5, 24, 14, 36, 3, 317, DateTimeKind.Utc).AddTicks(8203),
                             Description = "5% discount for preferred customers",
                             DiscountPercent = 5m,
                             IsActive = true,
@@ -6733,7 +6733,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 3,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 5, 21, 14, 32, 24, 337, DateTimeKind.Utc).AddTicks(8543),
+                            CreatedAt = new DateTime(2026, 5, 24, 14, 36, 3, 317, DateTimeKind.Utc).AddTicks(8204),
                             Description = "10% discount for premium customers",
                             DiscountPercent = 10m,
                             IsActive = true,
@@ -8634,6 +8634,21 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.ToTable("YearEndCloses");
                 });
 
+            modelBuilder.Entity("VendorInventoryCategories", b =>
+                {
+                    b.Property<int>("InventoryCategoryLookupId")
+                        .HasColumnType("int");
+
+                    b.Property<int>("VendorId")
+                        .HasColumnType("int");
+
+                    b.HasKey("InventoryCategoryLookupId", "VendorId");
+
+                    b.HasIndex("VendorId");
+
+                    b.ToTable("VendorInventoryCategories");
+                });
+
             modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityRoleClaim<string>", b =>
                 {
                     b.HasOne("Microsoft.AspNetCore.Identity.IdentityRole", null)
@@ -10372,6 +10387,21 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.Navigation("JournalEntry");
                 });
 
+            modelBuilder.Entity("VendorInventoryCategories", b =>
+                {
+                    b.HasOne("PowderCoating.Core.Entities.InventoryCategoryLookup", null)
+                        .WithMany()
+                        .HasForeignKey("InventoryCategoryLookupId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("PowderCoating.Core.Entities.Vendor", null)
+                        .WithMany()
+                        .HasForeignKey("VendorId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
             modelBuilder.Entity("PowderCoating.Core.Entities.Account", b =>
                 {
                     b.Navigation("BillLineItems");

src/PowderCoating.Web/Controllers/InventoryController.cs

@@ -1495,8 +1495,20 @@ public class InventoryController : Controller
         var companyId = _tenantContext.GetCurrentCompanyId() ?? 0;
         ViewBag.AiInventoryAssistEnabled = await _subscriptionService.IsAiInventoryAssistEnabledAsync(companyId);
 
-        var vendors = await _unitOfWork.Vendors.FindAsync(v => v.CompanyId == companyId);
-        ViewBag.Vendors = new SelectList(vendors.Where(s => s.IsActive).OrderBy(s => s.CompanyName), "Id", "CompanyName");
+        var vendors = (await _unitOfWork.Vendors.FindAsync(v => v.IsActive, false, v => v.Categories))
+            .OrderBy(v => v.CompanyName).ToList();
+        ViewBag.Vendors = new SelectList(vendors, "Id", "CompanyName");
+
+        // Build {categoryId: [vendorId, ...]} so the inventory form can filter vendors by category
+        var categoryVendorMap = new Dictionary<string, List<int>>();
+        foreach (var v in vendors)
+            foreach (var cat in v.Categories)
+            {
+                var key = cat.Id.ToString();
+                if (!categoryVendorMap.ContainsKey(key)) categoryVendorMap[key] = new List<int>();
+                categoryVendorMap[key].Add(v.Id);
+            }
+        ViewBag.CategoryVendorMapJson = System.Text.Json.JsonSerializer.Serialize(categoryVendorMap);
 
         // Load categories from lookup table
         var allCategories = await _unitOfWork.InventoryCategoryLookups.FindAsync(c => c.CompanyId == companyId);

src/PowderCoating.Web/Controllers/MaintenanceController.cs

@@ -580,7 +580,7 @@ public class MaintenanceController : Controller
                 // Calculate next scheduled maintenance
                 if (equipment.RecommendedMaintenanceIntervalDays > 0)
                 {
-                    equipment.NextScheduledMaintenance = DateTime.UtcNow.AddDays(equipment.RecommendedMaintenanceIntervalDays);
+                    equipment.NextScheduledMaintenance = DateTime.UtcNow.AddDays(equipment.RecommendedMaintenanceIntervalDays.Value);
                 }
 
                 equipment.UpdatedAt = DateTime.UtcNow;

src/PowderCoating.Web/Controllers/VendorsController.cs

@@ -181,6 +181,7 @@ public class VendorsController : Controller
     public async Task<IActionResult> Create(bool inline = false)
     {
         await PopulateExpenseAccountsAsync();
+        await PopulateVendorCategoriesAsync();
         if (inline)
             return PartialView(new CreateVendorDto());
         return View(new CreateVendorDto());
@@ -207,6 +208,7 @@ public class VendorsController : Controller
                 return Json(new { success = false, errors });
             }
             await PopulateExpenseAccountsAsync();
+            await PopulateVendorCategoriesAsync(dto.CategoryIds);
             return View(dto);
         }
 
@@ -216,6 +218,12 @@ public class VendorsController : Controller
             var vendor = _mapper.Map<Vendor>(dto);
             vendor.CompanyId = currentUser!.CompanyId;
 
+            if (dto.CategoryIds.Any())
+            {
+                var cats = await _unitOfWork.InventoryCategoryLookups.FindAsync(c => dto.CategoryIds.Contains(c.Id));
+                vendor.Categories = cats.ToList();
+            }
+
             await _unitOfWork.Vendors.AddAsync(vendor);
             await _unitOfWork.CompleteAsync();
 
@@ -247,14 +255,16 @@ public class VendorsController : Controller
 
         try
         {
-            var vendor = await _unitOfWork.Vendors.GetByIdAsync(id.Value);
+            var vendor = await _unitOfWork.Vendors.GetByIdAsync(id.Value, false, v => v.Categories);
             if (vendor == null)
             {
                 return NotFound();
             }
 
             var dto = _mapper.Map<UpdateVendorDto>(vendor);
+            dto.CategoryIds = vendor.Categories.Select(c => c.Id).ToList();
             await PopulateExpenseAccountsAsync();
+            await PopulateVendorCategoriesAsync(dto.CategoryIds);
             return View(dto);
         }
         catch (Exception ex)
@@ -282,18 +292,27 @@ public class VendorsController : Controller
         if (!ModelState.IsValid)
         {
             await PopulateExpenseAccountsAsync();
+            await PopulateVendorCategoriesAsync(dto.CategoryIds);
             return View(dto);
         }
 
         try
         {
-            var vendor = await _unitOfWork.Vendors.GetByIdAsync(id);
+            var vendor = await _unitOfWork.Vendors.GetByIdAsync(id, false, v => v.Categories);
             if (vendor == null)
             {
                 return NotFound();
             }
 
             _mapper.Map(dto, vendor);
+
+            vendor.Categories.Clear();
+            if (dto.CategoryIds.Any())
+            {
+                var cats = await _unitOfWork.InventoryCategoryLookups.FindAsync(c => dto.CategoryIds.Contains(c.Id));
+                foreach (var cat in cats) vendor.Categories.Add(cat);
+            }
+
             await _unitOfWork.Vendors.UpdateAsync(vendor);
             await _unitOfWork.CompleteAsync();
 
@@ -413,6 +432,20 @@ public class VendorsController : Controller
     /// purchases) in addition to regular operating expenses. A "— None —" placeholder is prepended so
     /// the field is optional — not every vendor needs a default account pre-set.
     /// </summary>
+    /// <summary>
+    /// Populates ViewBag.VendorCategories with active inventory categories for the checkbox list,
+    /// and ViewBag.SelectedCategoryIds with the IDs already assigned to the vendor being edited.
+    /// </summary>
+    private async Task PopulateVendorCategoriesAsync(IEnumerable<int>? selectedIds = null)
+    {
+        var companyId = (await _userManager.GetUserAsync(User))!.CompanyId;
+        var cats = (await _unitOfWork.InventoryCategoryLookups.FindAsync(c => c.CompanyId == companyId && c.IsActive))
+            .OrderBy(c => c.DisplayOrder)
+            .ToList();
+        ViewBag.VendorCategories = cats;
+        ViewBag.SelectedCategoryIds = (selectedIds ?? Enumerable.Empty<int>()).ToHashSet();
+    }
+
     private async Task PopulateExpenseAccountsAsync()
     {
         var accounts = (await _unitOfWork.Accounts.FindAsync(

src/PowderCoating.Web/Helpers/HelpKnowledgeBase.cs

@@ -466,7 +466,8 @@ public static class HelpKnowledgeBase
         Filter by item, date range, and transaction type. Summary pills show total lbs received, used, and net adjustments. Access from the sidebar ("Inventory Activity") or via "View Activity History" on any item's Details page (pre-filtered to that item).
 
         **QR Code Labels & Mobile Usage Logging:**
-        - Print a QR label from any item's Details page → click "Print QR Label" → opens a standalone print page with the item name, SKU, colour, and QR code. Print and stick on the bag/bin.
+        - Print a QR label from any item's Details page OR from the QR icon in the Actions column on the Inventory list page → click "Print QR Label" → a preview modal opens with the label (item name, SKU, colour, finish, and QR code). Click "Print Label" inside the modal to send to your printer without opening a new tab.
+        - You can also print from the list page without opening the item: click the QR icon (first button in the action column) next to any row.
         - Scan the QR code with a phone camera → opens the mobile-friendly Log Usage page at /Inventory/Scan/[item-id]
         - On the scan page: select a job (My Jobs shows jobs assigned to the logged-in user; Other Jobs shows all open jobs; No Job logs without a reference), enter quantity used (live balance preview shown), choose reason (Job Usage / Waste / Correction / Transfer Out), add optional notes, tap Save
         - After saving: success screen with "Log Another Item for This Job" (returns to scan with same job pre-selected) or "Back to Inventory" / "View Item Details"

src/PowderCoating.Web/Program.cs

@@ -671,8 +671,8 @@ System.Globalization.CultureInfo.DefaultThreadCurrentUICulture = cultureInfo;
 // SECURITY: Add security headers middleware
 app.Use(async (context, next) =>
 {
-    // Prevent clickjacking
-    context.Response.Headers.Append("X-Frame-Options", "DENY");
+    // Prevent clickjacking — SAMEORIGIN so our own iframe embeds (QR labels, etc.) still work
+    context.Response.Headers.Append("X-Frame-Options", "SAMEORIGIN");
 
     // Prevent MIME type sniffing
     context.Response.Headers.Append("X-Content-Type-Options", "nosniff");
@@ -699,7 +699,8 @@ app.Use(async (context, next) =>
         "font-src 'self' https://fonts.gstatic.com https://cdn.jsdelivr.net; " +
         "img-src 'self' data: https:; " +
         $"connect-src {cspConnectSrc}; " +
-        "frame-src https://js.stripe.com https://hooks.stripe.com");
+        "frame-src 'self' https://js.stripe.com https://hooks.stripe.com; " +
+        "frame-ancestors 'self'");
 
     // Referrer Policy - control referrer information
     context.Response.Headers.Append("Referrer-Policy", "strict-origin-when-cross-origin");

src/PowderCoating.Web/Views/Help/Inventory.cshtml

@@ -347,10 +347,14 @@
             </p>
 
             <h3 class="h6 fw-semibold mt-4 mb-2">Printing a label</h3>
+            <p>You can print from two places &mdash; the item's Details page, or directly from the list without opening the item.</p>
             <ol class="mb-3">
-                <li class="mb-1">Open the inventory item's Details page.</li>
-                <li class="mb-1">Click <strong>Print QR Label</strong> in the Actions panel &mdash; the label opens in a new tab.</li>
-                <li class="mb-1">Click <strong>Print Label</strong> and send it to your printer. The label is sized for a standard 3.5&Prime; label and includes the item name, SKU, colour, finish, and manufacturer.</li>
+                <li class="mb-1">
+                    <strong>From the list:</strong> click the <i class="bi bi-qr-code"></i> QR icon (first button in the Actions column) next to any row.
+                    <br /><strong>From Details:</strong> click <strong>Print QR Label</strong> in the Actions panel.
+                </li>
+                <li class="mb-1">A preview modal opens showing the label &mdash; item name, SKU, colour, finish, and QR code.</li>
+                <li class="mb-1">Click <strong>Print Label</strong> inside the modal to send it to your printer. No new tab is opened; printing happens directly in the modal. The label is sized for a standard 3.5&Prime; label.</li>
             </ol>
 
             <h3 class="h6 fw-semibold mt-4 mb-2">Scanning and logging usage</h3>

src/PowderCoating.Web/Views/Help/Vendors.cshtml

@@ -149,6 +149,43 @@
             </div>
         </section>
 
+        <section id="supply-categories" class="mb-5">
+            <h2 class="h4 fw-bold border-bottom pb-2 mb-3">
+                <i class="bi bi-tags text-primary me-2"></i>Supply Categories
+            </h2>
+            <p>
+                Each vendor can be tagged with one or more <strong>Supply Categories</strong> &mdash; for example,
+                <em>Powder</em>, <em>Chemical</em>, or <em>Consumables</em>. These tags tell the system what types of
+                inventory items this vendor supplies.
+            </p>
+            <p>
+                When you add or edit an inventory item and choose a <strong>Category</strong>, the vendor dropdown
+                automatically filters to show only vendors tagged for that category. This prevents accidentally
+                selecting an unrelated supplier.
+            </p>
+            <ul class="mb-3">
+                <li>A vendor can belong to <strong>multiple categories</strong> &mdash; check as many boxes as apply.</li>
+                <li>If <strong>no vendor</strong> in your list is tagged for the selected category, the dropdown falls back to
+                    showing all active vendors so you are never blocked.</li>
+                <li>A <em>&ldquo;Showing vendors for this category&rdquo;</em> note appears below the dropdown when the filter is
+                    active. Click <strong>Show all</strong> in that note to temporarily override the filter.</li>
+            </ul>
+            <p>To tag a vendor with supply categories:</p>
+            <ol class="mb-3">
+                <li class="mb-1">Open the vendor's Edit page (click the vendor name in the list, then <strong>Edit</strong>).</li>
+                <li class="mb-1">In the <strong>Supply Categories</strong> section, check the boxes that apply.</li>
+                <li class="mb-1">Click <strong>Save Vendor</strong>.</li>
+            </ol>
+            <div class="alert alert-permanent alert-info d-flex gap-2 mb-0" role="alert">
+                <i class="bi bi-lightbulb-fill flex-shrink-0 mt-1"></i>
+                <div>
+                    Supply categories are the same categories used on your inventory items. If you add a new category
+                    under <strong>Settings &rsaquo; Inventory Categories</strong>, it will appear automatically in the vendor
+                    checkboxes.
+                </div>
+            </div>
+        </section>
+
         <section id="deactivating-a-vendor" class="mb-5">
             <h2 class="h4 fw-bold border-bottom pb-2 mb-3">
                 <i class="bi bi-truck text-primary me-2" style="text-decoration:line-through"></i>Deactivating a Vendor
@@ -186,6 +223,7 @@
                     <a class="nav-link py-1 px-3 small text-body" href="#default-expense-account">Default Expense Account</a>
                     <a class="nav-link py-1 px-3 small text-body" href="#payment-terms">Payment Terms</a>
                     <a class="nav-link py-1 px-3 small text-body" href="#preferred-vendor">Preferred Vendor</a>
+                    <a class="nav-link py-1 px-3 small text-body" href="#supply-categories">Supply Categories</a>
                     <a class="nav-link py-1 px-3 small text-body" href="#vendor-details">Vendor Details Page</a>
                     <a class="nav-link py-1 px-3 small text-body" href="#deactivating-a-vendor">Deactivating a Vendor</a>
                 </nav>

src/PowderCoating.Web/Views/Inventory/Create.cshtml

@@ -345,6 +345,10 @@
                                     <option value="">Select vendor</option>
                                     <option value="__new__">+ Add New Vendor&hellip;</option>
                                 </select>
+                                <div id="vendor-filter-note" class="form-text d-none">
+                                    <i class="bi bi-funnel me-1 text-info"></i><span class="text-info">Showing vendors for this category.</span>
+                                    <a href="#" id="vendor-filter-clear" class="ms-1">Show all</a>
+                                </div>
                                 <span asp-validation-for="PrimaryVendorId" class="text-danger"></span>
                             </div>
                         </div>
@@ -438,4 +442,38 @@
     {
         <script src="~/js/inventory-label-scan.js"></script>
     }
+    <script>
+    (function () {
+        const categoryVendorMap = @Html.Raw(ViewBag.CategoryVendorMapJson ?? "{}");
+        const vendorSelect = document.getElementById('field-vendor');
+        const allVendorOptions = Array.from(vendorSelect.options).map(o => ({ v: o.value, t: o.text }));
+
+        function filterVendors(catId, forceAll) {
+            const vendorIds = (!forceAll && catId) ? (categoryVendorMap[catId] || []) : [];
+            const isFiltered = vendorIds.length > 0;
+            const currentVal = vendorSelect.value;
+
+            vendorSelect.innerHTML = '';
+            allVendorOptions.forEach(function (opt) {
+                if (!isFiltered || !opt.v || opt.v === '__new__' || vendorIds.includes(Number(opt.v)))
+                    vendorSelect.add(new Option(opt.t, opt.v));
+            });
+
+            if (Array.from(vendorSelect.options).some(o => o.value === currentVal))
+                vendorSelect.value = currentVal;
+
+            document.getElementById('vendor-filter-note').classList.toggle('d-none', !isFiltered);
+        }
+
+        document.getElementById('field-category').addEventListener('change', function () {
+            filterVendors(this.value, false);
+        });
+        document.getElementById('vendor-filter-clear')?.addEventListener('click', function (e) {
+            e.preventDefault();
+            filterVendors(document.getElementById('field-category').value, true);
+        });
+
+        filterVendors(document.getElementById('field-category').value, false);
+    })();
+    </script>
 }

src/PowderCoating.Web/Views/Inventory/Edit.cshtml

@@ -341,6 +341,10 @@
                                     <option value="">Select vendor</option>
                                     <option value="__new__">+ Add New Vendor&hellip;</option>
                                 </select>
+                                <div id="vendor-filter-note" class="form-text d-none">
+                                    <i class="bi bi-funnel me-1 text-info"></i><span class="text-info">Showing vendors for this category.</span>
+                                    <a href="#" id="vendor-filter-clear" class="ms-1">Show all</a>
+                                </div>
                                 <span asp-validation-for="PrimaryVendorId" class="text-danger"></span>
                             </div>
                             <div class="col-12">
@@ -457,4 +461,39 @@
     {
         <script src="~/js/inventory-label-scan.js"></script>
     }
+    <script>
+    (function () {
+        const categoryVendorMap = @Html.Raw(ViewBag.CategoryVendorMapJson ?? "{}");
+        const vendorSelect = document.getElementById('field-vendor');
+        const allVendorOptions = Array.from(vendorSelect.options).map(o => ({ v: o.value, t: o.text }));
+
+        function filterVendors(catId, forceAll) {
+            const vendorIds = (!forceAll && catId) ? (categoryVendorMap[catId] || []) : [];
+            const isFiltered = vendorIds.length > 0;
+            const currentVal = vendorSelect.value;
+
+            vendorSelect.innerHTML = '';
+            allVendorOptions.forEach(function (opt) {
+                if (!isFiltered || !opt.v || opt.v === '__new__' || vendorIds.includes(Number(opt.v)))
+                    vendorSelect.add(new Option(opt.t, opt.v));
+            });
+
+            if (Array.from(vendorSelect.options).some(o => o.value === currentVal))
+                vendorSelect.value = currentVal;
+
+            document.getElementById('vendor-filter-note').classList.toggle('d-none', !isFiltered);
+        }
+
+        document.getElementById('field-category').addEventListener('change', function () {
+            filterVendors(this.value, false);
+        });
+        document.getElementById('vendor-filter-clear')?.addEventListener('click', function (e) {
+            e.preventDefault();
+            filterVendors(document.getElementById('field-category').value, true);
+        });
+
+        // Apply on load — Edit already has a category selected
+        filterVendors(document.getElementById('field-category').value, false);
+    })();
+    </script>
 }

src/PowderCoating.Web/Views/Inventory/Index.cshtml

@@ -340,6 +340,11 @@
                                 </td>
                                 <td class="text-end pe-4">
                                     <div class="btn-group btn-group-sm">
+                                        <button type="button" class="btn btn-outline-secondary"
+                                                title="Print QR Label"
+                                                onclick="openQrLabelModal(@item.Id, event)">
+                                            <i class="bi bi-qr-code"></i>
+                                        </button>
                                         <a asp-action="Details" asp-route-id="@item.Id" class="btn btn-outline-primary" title="View Details">
                                             <i class="bi bi-eye"></i>
                                         </a>
@@ -454,6 +459,10 @@
                             </div>
 
                             <div class="mobile-card-footer">
+                                <button type="button" class="btn btn-sm btn-outline-secondary"
+                                        onclick="openQrLabelModal(@item.Id, event)">
+                                    <i class="bi bi-qr-code me-1"></i>QR Label
+                                </button>
                                 <a href="@Url.Action("Details", new { id = item.Id })"
                                    class="btn btn-sm btn-outline-primary"
                                    onclick="event.stopPropagation();">
@@ -477,8 +486,42 @@
     }
 </div>
 
+@* QR Label Modal (shared across all items — src set dynamically by JS) *@
+<div class="modal fade" id="qrLabelModal" tabindex="-1" aria-labelledby="qrLabelModalLabel" aria-hidden="true">
+    <div class="modal-dialog modal-dialog-centered">
+        <div class="modal-content">
+            <div class="modal-header py-2">
+                <h6 class="modal-title" id="qrLabelModalLabel">
+                    <i class="bi bi-qr-code me-2"></i>QR Label
+                </h6>
+                <button type="button" class="btn-close" data-bs-dismiss="modal"></button>
+            </div>
+            <div class="modal-body p-0 d-flex justify-content-center" style="background:#f0f0f0;min-height:360px;">
+                <iframe id="qrLabelFrame"
+                        src="about:blank"
+                        style="width:100%;height:400px;border:none;"
+                        title="QR Label Preview"></iframe>
+            </div>
+            <div class="modal-footer py-2">
+                <button type="button" class="btn btn-primary btn-sm"
+                        onclick="document.getElementById('qrLabelFrame').contentWindow.print()">
+                    <i class="bi bi-printer me-2"></i>Print Label
+                </button>
+                <button type="button" class="btn btn-outline-secondary btn-sm" data-bs-dismiss="modal">Close</button>
+            </div>
+        </div>
+    </div>
+</div>
+
 @section Scripts {
     <script>
+        function openQrLabelModal(itemId, e) {
+            e.stopPropagation();
+            const frame = document.getElementById('qrLabelFrame');
+            frame.src = '@Url.Action("Label", "Inventory")/' + itemId + '?embed=true';
+            bootstrap.Modal.getOrCreateInstance(document.getElementById('qrLabelModal')).show();
+        }
+
         // Make table rows clickable
         document.querySelectorAll('.inventory-row').forEach(row => {
             row.addEventListener('click', function(e) {

src/PowderCoating.Web/Views/Vendors/Create.cshtml

@@ -195,6 +195,27 @@
                         </div>
                     </div>
 
+                    <!-- Supply Categories -->
+                    @if (ViewBag.VendorCategories is IEnumerable<PowderCoating.Core.Entities.InventoryCategoryLookup> cats && cats.Any())
+                    {
+                    <div class="mb-4">
+                        <h5 class="border-bottom pb-2 mb-3">
+                            <i class="bi bi-tags me-2 text-primary"></i>Supply Categories
+                        </h5>
+                        <div class="d-flex flex-wrap gap-3">
+                            @foreach (var cat in cats)
+                            {
+                                <div class="form-check">
+                                    <input class="form-check-input" type="checkbox"
+                                           name="CategoryIds" value="@cat.Id" id="cat_@cat.Id" />
+                                    <label class="form-check-label" for="cat_@cat.Id">@cat.DisplayName</label>
+                                </div>
+                            }
+                        </div>
+                        <div class="form-text">Tag this vendor with the types of supplies they provide. Used to filter the vendor list when adding inventory items.</div>
+                    </div>
+                    }
+
                     <!-- Notes Section -->
                     <div class="mb-4">
                         <h5 class="border-bottom pb-2 mb-3">

src/PowderCoating.Web/Views/Vendors/Edit.cshtml

@@ -198,6 +198,29 @@
                         </div>
                     </div>
 
+                    <!-- Supply Categories -->
+                    @if (ViewBag.VendorCategories is IEnumerable<PowderCoating.Core.Entities.InventoryCategoryLookup> cats && cats.Any())
+                    {
+                    var selectedCatIds = (HashSet<int>)ViewBag.SelectedCategoryIds;
+                    <div class="mb-4">
+                        <h5 class="border-bottom pb-2 mb-3">
+                            <i class="bi bi-tags me-2 text-primary"></i>Supply Categories
+                        </h5>
+                        <div class="d-flex flex-wrap gap-3">
+                            @foreach (var cat in cats)
+                            {
+                                <div class="form-check">
+                                    <input class="form-check-input" type="checkbox"
+                                           name="CategoryIds" value="@cat.Id" id="cat_@cat.Id"
+                                           @(selectedCatIds.Contains(cat.Id) ? "checked" : "") />
+                                    <label class="form-check-label" for="cat_@cat.Id">@cat.DisplayName</label>
+                                </div>
+                            }
+                        </div>
+                        <div class="form-text">Tag this vendor with the types of supplies they provide. Used to filter the vendor list when adding inventory items.</div>
+                    </div>
+                    }
+
                     <!-- Notes Section -->
                     <div class="mb-4">
                         <h5 class="border-bottom pb-2 mb-3">