feat(po): make vendor field a searchable combobox

The vendor field on the PO forms was a plain native <select>, forcing
users to scroll the full vendor list. Mirror the item-search UX with a
searchable combobox that filters by vendor name and formal code
(vendorId), case-insensitively. The vendor list is already client-side,
so this is a pure in-memory filter — no API or DB change.

New VendorSelect component (components/ui/vendor-select.tsx) is a
self-contained portal-rendered combobox posting a hidden vendorId input,
so it drops into all three PO forms unchanged on the server:
- po/new/new-po-form
- po/[id]/edit/edit-po-form
- approvals/[id]/manager-edit-po-form

Preserves the optional field, "No vendor selected" empty option, and the
"{name} (CODE)" / "(unverified)" label. Unverified vendors (null code)
remain findable by name. Adds unit tests for the filter logic and
component behaviour.

Fixes #109

App/app/(portal)/approvals/[id]/manager-edit-po-form.tsx

@@ -8,6 +8,7 @@ import type { LineItemInput } from "@/lib/validations/po";
 import type { Vendor, PurchaseOrder } from "@prisma/client";
 import type { VesselOption, AccountGroup, CompanyOption } from "@/app/(portal)/po/new/new-po-form";
 import { SearchableSelect } from "@/components/ui/searchable-select";
+import { VendorSelect } from "@/components/ui/vendor-select";
 import { DeliveryLocationField } from "@/components/po/delivery-location-field";
 import { PoTermsEditor } from "@/components/po/po-terms-editor";
 import type { CatalogueCategory, PoTerm } from "@/lib/terms";
@@ -244,14 +245,7 @@ export function ManagerEditPoForm({ po, vessels, accounts, vendors, companies, d
         <section>
           <h3 className="text-xs font-bold text-amber-800 uppercase tracking-wider mb-3">Vendor</h3>
           <label className={LABEL}>Vendor</label>
-          <select name="vendorId" defaultValue={po.vendorId ?? ""} className={INPUT}>
+          <VendorSelect name="vendorId" vendors={vendors} initialValue={po.vendorId ?? ""} />
-            <option value="">No vendor selected</option>
-            {vendors.map((v) => (
-              <option key={v.id} value={v.id}>
-                {v.name} {v.vendorId ? `(${v.vendorId})` : "(unverified)"}
-              </option>
-            ))}
-          </select>
         </section>
 
         {/* Line Items */}

App/app/(portal)/po/[id]/edit/edit-po-form.tsx

@@ -7,6 +7,7 @@ import type { Vendor, PurchaseOrder } from "@prisma/client";
 import type { VesselOption, AccountGroup, CompanyOption } from "@/app/(portal)/po/new/new-po-form";
 import { LineItemsEditor } from "@/components/po/po-line-items-editor";
 import { SearchableSelect } from "@/components/ui/searchable-select";
+import { VendorSelect } from "@/components/ui/vendor-select";
 import { DeliveryLocationField } from "@/components/po/delivery-location-field";
 import { PoTermsEditor } from "@/components/po/po-terms-editor";
 import type { CatalogueCategory, PoTerm } from "@/lib/terms";
@@ -255,14 +256,7 @@ export function EditPoForm({ po, vessels, accounts, vendors, companies, delivery
       {/* Vendor */}
       <section className="rounded-lg border border-neutral-200 bg-white p-6">
         <h2 className="text-base font-semibold text-neutral-900 mb-4">Vendor</h2>
-        <select name="vendorId" defaultValue={po.vendorId ?? ""} className={INPUT_CLS}>
+        <VendorSelect name="vendorId" vendors={vendors} initialValue={po.vendorId ?? ""} />
-          <option value="">No vendor selected</option>
-          {vendors.map((v) => (
-            <option key={v.id} value={v.id}>
-              {v.name} {v.vendorId ? `(${v.vendorId})` : "(unverified)"}
-            </option>
-          ))}
-        </select>
       </section>
 
       {/* Terms & Conditions */}

App/app/(portal)/po/new/new-po-form.tsx

@@ -7,6 +7,7 @@ import type { Vendor } from "@prisma/client";
 import { LineItemsEditor } from "@/components/po/po-line-items-editor";
 import { FileUploader } from "@/components/po/file-uploader";
 import { SearchableSelect } from "@/components/ui/searchable-select";
+import { VendorSelect } from "@/components/ui/vendor-select";
 import { DeliveryLocationField } from "@/components/po/delivery-location-field";
 import { PoTermsEditor } from "@/components/po/po-terms-editor";
 import type { CatalogueCategory, PoTerm } from "@/lib/terms";
@@ -41,7 +42,6 @@ export function NewPoForm({ vessels, accounts, vendors, companies, deliveryOptio
   const [lineItems, setLineItems] = useState<LineItemInput[]>(
     initialLineItems && initialLineItems.length > 0 ? initialLineItems : [EMPTY_LINE]
   );
-  const [vendorId, setVendorId] = useState(initialVendorId ?? "");
   const [files, setFiles] = useState<File[]>([]);
   const [submitting, setSubmitting] = useState<"draft" | "submit" | null>(null);
   const [error, setError] = useState("");
@@ -229,19 +229,7 @@ export function NewPoForm({ vessels, accounts, vendors, companies, deliveryOptio
           <label className="block text-sm font-medium text-neutral-700 mb-1.5">
             Vendor (optional — can be added later)
           </label>
-          <select
+          <VendorSelect name="vendorId" vendors={vendors} initialValue={initialVendorId ?? ""} />
-            name="vendorId"
-            value={vendorId}
-            onChange={(e) => setVendorId(e.target.value)}
-            className={INPUT_CLS}
-          >
-            <option value="">No vendor selected</option>
-            {vendors.map((v) => (
-              <option key={v.id} value={v.id}>
-                {v.name} {v.vendorId ? `(${v.vendorId})` : "(unverified)"}
-              </option>
-            ))}
-          </select>
         </div>
       </section>
 

App/components/ui/vendor-select.tsx

@@ -0,0 +1,211 @@
+"use client";
+
+import { useState, useRef, useEffect, useLayoutEffect, useCallback } from "react";
+import { createPortal } from "react-dom";
+import { ChevronDown, Search, X } from "lucide-react";
+
+export type VendorOption = { id: string; name: string; vendorId: string | null };
+
+/**
+ * Filter vendors by a free-text query, matching case-insensitively against the
+ * vendor name and the formal code (`vendorId`). An empty/whitespace query
+ * returns the full list unchanged.
+ */
+export function filterVendors<T extends VendorOption>(vendors: T[], query: string): T[] {
+  const q = query.trim().toLowerCase();
+  if (!q) return vendors;
+  return vendors.filter(
+    (v) =>
+      v.name.toLowerCase().includes(q) ||
+      (v.vendorId ? v.vendorId.toLowerCase().includes(q) : false)
+  );
+}
+
+/** Label shown for a vendor: "{name} (CODE)" when verified, "{name} (unverified)" otherwise. */
+export function vendorLabel(v: VendorOption): string {
+  return `${v.name} ${v.vendorId ? `(${v.vendorId})` : "(unverified)"}`;
+}
+
+interface Props {
+  name: string;
+  vendors: VendorOption[];
+  /** Initial selected vendor id (uncontrolled — the component owns its state). */
+  initialValue?: string;
+  placeholder?: string;
+  /** Optional callback when the selection changes. */
+  onChange?: (value: string) => void;
+}
+
+export function VendorSelect({
+  name,
+  vendors,
+  initialValue = "",
+  placeholder = "No vendor selected",
+  onChange,
+}: Props) {
+  const [value, setValue] = useState(initialValue);
+  const [open, setOpen] = useState(false);
+  const [query, setQuery] = useState("");
+  const containerRef = useRef<HTMLDivElement>(null);
+  const searchRef = useRef<HTMLInputElement>(null);
+  const [portalStyle, setPortalStyle] = useState<React.CSSProperties>({});
+  const [mounted, setMounted] = useState(false);
+
+  useEffect(() => { setMounted(true); }, []);
+
+  const updatePortalPos = useCallback(() => {
+    if (!containerRef.current) return;
+    const rect = containerRef.current.getBoundingClientRect();
+    setPortalStyle({
+      position: "fixed",
+      top: rect.bottom + 4,
+      left: rect.left,
+      width: rect.width,
+      zIndex: 9999,
+    });
+  }, []);
+
+  useLayoutEffect(() => {
+    if (!open) return;
+    updatePortalPos();
+  }, [open, updatePortalPos]);
+
+  useEffect(() => {
+    if (!open) return;
+    window.addEventListener("scroll", updatePortalPos, true);
+    window.addEventListener("resize", updatePortalPos);
+    return () => {
+      window.removeEventListener("scroll", updatePortalPos, true);
+      window.removeEventListener("resize", updatePortalPos);
+    };
+  }, [open, updatePortalPos]);
+
+  // Close on outside click / Escape
+  useEffect(() => {
+    if (!open) return;
+    function handleKey(e: KeyboardEvent) {
+      if (e.key === "Escape") { setOpen(false); setQuery(""); }
+    }
+    function handleClick(e: MouseEvent) {
+      if (containerRef.current && !containerRef.current.contains(e.target as Node)) {
+        setOpen(false);
+        setQuery("");
+      }
+    }
+    document.addEventListener("keydown", handleKey);
+    document.addEventListener("mousedown", handleClick);
+    return () => {
+      document.removeEventListener("keydown", handleKey);
+      document.removeEventListener("mousedown", handleClick);
+    };
+  }, [open]);
+
+  useEffect(() => {
+    if (open) searchRef.current?.focus();
+  }, [open]);
+
+  const selected = vendors.find((v) => v.id === value);
+  const selectedLabel = selected ? vendorLabel(selected) : "";
+
+  const filtered = filterVendors(vendors, query);
+
+  const select = useCallback((id: string) => {
+    setValue(id);
+    onChange?.(id);
+    setOpen(false);
+    setQuery("");
+  }, [onChange]);
+
+  const handleClear = useCallback((e: React.MouseEvent) => {
+    e.stopPropagation();
+    setValue("");
+    onChange?.("");
+  }, [onChange]);
+
+  const dropdownPanel = (
+    <div
+      style={portalStyle}
+      className="rounded-lg border border-neutral-200 bg-white shadow-xl"
+    >
+      {/* Search input */}
+      <div className="flex items-center gap-2 p-2 border-b border-neutral-100">
+        <Search className="h-4 w-4 text-neutral-400 shrink-0" />
+        <input
+          ref={searchRef}
+          type="text"
+          value={query}
+          onChange={(e) => setQuery(e.target.value)}
+          placeholder="Search by name or code…"
+          className="flex-1 text-sm outline-none placeholder:text-neutral-400"
+        />
+        {query && (
+          <button type="button" onClick={() => setQuery("")} className="text-neutral-300 hover:text-neutral-500">
+            <X className="h-3.5 w-3.5" />
+          </button>
+        )}
+      </div>
+
+      {/* Options list */}
+      <div className="max-h-72 overflow-y-auto overscroll-contain [&::-webkit-scrollbar]:w-1.5 [&::-webkit-scrollbar-track]:bg-transparent [&::-webkit-scrollbar-thumb]:rounded-full [&::-webkit-scrollbar-thumb]:bg-neutral-300">
+        {/* "No vendor selected" empty option — always available */}
+        <button
+          type="button"
+          onMouseDown={(e) => { e.preventDefault(); select(""); }}
+          className={`w-full text-left px-3 py-2 text-sm hover:bg-primary-50 transition-colors
+            ${value === "" ? "bg-primary-50 text-primary-700 font-medium" : "text-neutral-500"}`}
+        >
+          No vendor selected
+        </button>
+        {filtered.length === 0 ? (
+          <p className="px-3 py-5 text-sm text-center text-neutral-400">No vendors match &ldquo;{query}&rdquo;</p>
+        ) : (
+          filtered.map((v) => (
+            <button
+              key={v.id}
+              type="button"
+              onMouseDown={(e) => { e.preventDefault(); select(v.id); }}
+              className={`w-full text-left flex items-baseline gap-2.5 px-3 py-2 text-sm hover:bg-primary-50 transition-colors
+                ${value === v.id ? "bg-primary-50 text-primary-700 font-medium" : "text-neutral-800"}`}
+            >
+              <span className="flex-1 leading-snug">{v.name}</span>
+              <span className="font-mono text-xs text-neutral-400 shrink-0">
+                {v.vendorId ?? "unverified"}
+              </span>
+            </button>
+          ))
+        )}
+      </div>
+    </div>
+  );
+
+  return (
+    <div ref={containerRef} className="relative w-full">
+      <input type="hidden" name={name} value={value} />
+
+      <button
+        type="button"
+        onClick={() => setOpen((v) => !v)}
+        className={`w-full flex items-center justify-between gap-2 rounded-lg border
+          ${open ? "border-primary-500 ring-2 ring-primary-500/20" : "border-neutral-300"}
+          bg-white text-left transition-colors px-3 py-2.5 text-sm
+          focus:border-primary-500 focus:outline-none focus:ring-2 focus:ring-primary-500/20`}
+      >
+        <span className={`truncate flex-1 min-w-0 ${selectedLabel ? "text-neutral-900" : "text-neutral-400"}`}>
+          {selectedLabel || placeholder}
+        </span>
+        <span className="flex items-center gap-1 shrink-0">
+          {value && (
+            <span role="button" tabIndex={0} onClick={handleClear}
+              onKeyDown={(e) => e.key === "Enter" && handleClear(e as unknown as React.MouseEvent)}
+              className="text-neutral-300 hover:text-neutral-500 transition-colors">
+              <X className="h-4 w-4" />
+            </span>
+          )}
+          <ChevronDown className={`text-neutral-400 transition-transform h-4 w-4 ${open ? "rotate-180" : ""}`} />
+        </span>
+      </button>
+
+      {open && mounted && createPortal(dropdownPanel, document.body)}
+    </div>
+  );
+}

App/tests/unit/vendor-select.test.tsx

@@ -0,0 +1,116 @@
+import { describe, it, expect, vi } from "vitest";
+import { render, screen, fireEvent } from "@testing-library/react";
+import { filterVendors, vendorLabel, VendorSelect, type VendorOption } from "@/components/ui/vendor-select";
+
+const VENDORS: VendorOption[] = [
+  { id: "1", name: "Acme Marine Supplies", vendorId: "V-1001" },
+  { id: "2", name: "Bluewater Engineering", vendorId: "V-2002" },
+  { id: "3", name: "Coastal Spares", vendorId: null }, // unverified — no code
+  { id: "4", name: "Delta Pumps", vendorId: "ACME-99" },
+];
+
+// ── Pure filter logic ─────────────────────────────────────────────────────────
+
+describe("filterVendors", () => {
+  it("returns all vendors for an empty query", () => {
+    expect(filterVendors(VENDORS, "")).toHaveLength(4);
+  });
+
+  it("returns all vendors for a whitespace-only query", () => {
+    expect(filterVendors(VENDORS, "   ")).toHaveLength(4);
+  });
+
+  it("matches by name (case-insensitive)", () => {
+    const res = filterVendors(VENDORS, "bluewater");
+    expect(res.map((v) => v.id)).toEqual(["2"]);
+  });
+
+  it("matches by code (vendorId), case-insensitive", () => {
+    const res = filterVendors(VENDORS, "v-2002");
+    expect(res.map((v) => v.id)).toEqual(["2"]);
+  });
+
+  it("matches on a code substring even when the name does not contain it", () => {
+    // "acme" appears in vendor #1's name AND in vendor #4's code (ACME-99)
+    const res = filterVendors(VENDORS, "acme");
+    expect(res.map((v) => v.id).sort()).toEqual(["1", "4"]);
+  });
+
+  it("finds an unverified vendor (null code) by name only", () => {
+    expect(filterVendors(VENDORS, "coastal").map((v) => v.id)).toEqual(["3"]);
+    // ...and never crashes on the null code
+    expect(filterVendors(VENDORS, "9999")).toHaveLength(0);
+  });
+
+  it("returns no matches for an unrelated query", () => {
+    expect(filterVendors(VENDORS, "zzz")).toHaveLength(0);
+  });
+});
+
+describe("vendorLabel", () => {
+  it("formats a verified vendor as name (CODE)", () => {
+    expect(vendorLabel(VENDORS[0])).toBe("Acme Marine Supplies (V-1001)");
+  });
+  it("formats an unverified vendor as name (unverified)", () => {
+    expect(vendorLabel(VENDORS[2])).toBe("Coastal Spares (unverified)");
+  });
+});
+
+// ── Component behaviour ───────────────────────────────────────────────────────
+
+describe("VendorSelect", () => {
+  it("posts a hidden vendorId input with the empty default", () => {
+    const { container } = render(<VendorSelect name="vendorId" vendors={VENDORS} />);
+    const hidden = container.querySelector('input[name="vendorId"]') as HTMLInputElement;
+    expect(hidden).toBeTruthy();
+    expect(hidden.value).toBe("");
+  });
+
+  it("honours initialValue", () => {
+    const { container } = render(<VendorSelect name="vendorId" vendors={VENDORS} initialValue="2" />);
+    const hidden = container.querySelector('input[name="vendorId"]') as HTMLInputElement;
+    expect(hidden.value).toBe("2");
+    // Trigger shows the formatted label
+    expect(screen.getByText("Bluewater Engineering (V-2002)")).toBeTruthy();
+  });
+
+  it("opens and filters the list by typed query, then selects a vendor", () => {
+    const onChange = vi.fn();
+    const { container } = render(<VendorSelect name="vendorId" vendors={VENDORS} onChange={onChange} />);
+    fireEvent.click(screen.getByRole("button"));
+    const search = screen.getByPlaceholderText("Search by name or code…");
+    fireEvent.change(search, { target: { value: "v-2002" } });
+
+    // Only the matching vendor option is in the list
+    expect(screen.getByText("Bluewater Engineering")).toBeTruthy();
+    expect(screen.queryByText("Acme Marine Supplies")).toBeNull();
+
+    fireEvent.mouseDown(screen.getByText("Bluewater Engineering"));
+    expect(onChange).toHaveBeenCalledWith("2");
+    const hidden = container.querySelector('input[name="vendorId"]') as HTMLInputElement;
+    expect(hidden.value).toBe("2");
+  });
+
+  it("keeps 'No vendor selected' selectable to clear the choice", () => {
+    const onChange = vi.fn();
+    const { container } = render(
+      <VendorSelect name="vendorId" vendors={VENDORS} initialValue="1" onChange={onChange} />
+    );
+    // The trigger shows the current selection's label; click it to open.
+    fireEvent.click(screen.getByText("Acme Marine Supplies (V-1001)"));
+    // The empty option is always present, even before typing
+    fireEvent.mouseDown(screen.getByText("No vendor selected"));
+    expect(onChange).toHaveBeenLastCalledWith("");
+    const hidden = container.querySelector('input[name="vendorId"]') as HTMLInputElement;
+    expect(hidden.value).toBe("");
+  });
+
+  it("shows an empty-state message when nothing matches", () => {
+    render(<VendorSelect name="vendorId" vendors={VENDORS} />);
+    fireEvent.click(screen.getByRole("button"));
+    fireEvent.change(screen.getByPlaceholderText("Search by name or code…"), {
+      target: { value: "zzz" },
+    });
+    expect(screen.getByText(/No vendors match/)).toBeTruthy();
+  });
+});