feat(ares): ARES company lookup with prefill in customer/supplier modals

New /api/admin/ares proxy (browser cannot reach ares.gov.cz - CORS+CSP):
GET /ico/:ico and GET /search?q= map the MFCR REST API to the form
shape (street incl. orientation numbers, "511 01" PSC format, DIC).
Guarded by customers.create/edit + warehouse.manage; token errors map
to Czech messages. Shared AresAdornment button sits in the Nazev and
ICO fields of both modals: ICO mode fills directly, name mode searches
with a result picker. Tested against live ARES (BOHA, ICO 22599851).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/__tests__/ares.test.ts

@@ -0,0 +1,116 @@
+import { describe, it, expect, vi, afterEach } from "vitest";
+import { aresLookupByIco, aresSearchByName } from "../services/ares.service";
+
+// ARES is a true external — mock global fetch (the only allowed mock class).
+const SUBJECT = {
+  ico: "22599851",
+  obchodniJmeno: "BOHA Automation s.r.o.",
+  dic: "CZ22599851",
+  sidlo: {
+    nazevStatu: "Česká republika",
+    nazevObce: "Turnov",
+    nazevCastiObce: "Turnov",
+    nazevUlice: "Nádražní",
+    cisloDomovni: 485,
+    psc: 51101,
+    textovaAdresa: "Nádražní 485, 51101 Turnov",
+  },
+};
+
+function mockFetchOnce(status: number, body?: unknown) {
+  return vi.spyOn(globalThis, "fetch").mockResolvedValueOnce({
+    ok: status >= 200 && status < 300,
+    status,
+    json: async () => body,
+  } as Response);
+}
+
+afterEach(() => {
+  vi.restoreAllMocks();
+});
+
+describe("aresLookupByIco", () => {
+  it("maps a subject to the normalized prefill shape", async () => {
+    mockFetchOnce(200, SUBJECT);
+    const res = await aresLookupByIco("22599851");
+    expect(res).toEqual({
+      ico: "22599851",
+      dic: "CZ22599851",
+      name: "BOHA Automation s.r.o.",
+      street: "Nádražní 485",
+      city: "Turnov",
+      postal_code: "511 01",
+      country: "Česká republika",
+    });
+  });
+
+  it("builds Prague-style orientation numbers as 'Ulice 485/12a'", async () => {
+    mockFetchOnce(200, {
+      ...SUBJECT,
+      sidlo: {
+        ...SUBJECT.sidlo,
+        cisloOrientacni: 12,
+        cisloOrientacniPismeno: "a",
+      },
+    });
+    const res = await aresLookupByIco("22599851");
+    expect("street" in res && res.street).toBe("Nádražní 485/12a");
+  });
+
+  it("rejects a non-8-digit IČO without calling ARES", async () => {
+    const spy = vi.spyOn(globalThis, "fetch");
+    expect(await aresLookupByIco("123")).toEqual({ error: "invalid_ico" });
+    expect(await aresLookupByIco("abcdefgh")).toEqual({
+      error: "invalid_ico",
+    });
+    expect(spy).not.toHaveBeenCalled();
+  });
+
+  it("accepts an IČO with stray whitespace", async () => {
+    const spy = mockFetchOnce(200, SUBJECT);
+    const res = await aresLookupByIco(" 225 99851 ");
+    expect("ico" in res && res.ico).toBe("22599851");
+    expect(String(spy.mock.calls[0][0])).toContain("/22599851");
+  });
+
+  it("maps 404 to not_found and network failure to ares_unavailable", async () => {
+    mockFetchOnce(404);
+    expect(await aresLookupByIco("12345678")).toEqual({ error: "not_found" });
+
+    vi.spyOn(globalThis, "fetch").mockRejectedValueOnce(new Error("ETIMEDOUT"));
+    expect(await aresLookupByIco("12345678")).toEqual({
+      error: "ares_unavailable",
+    });
+  });
+});
+
+describe("aresSearchByName", () => {
+  it("maps the result list and sends the name in the POST body", async () => {
+    const spy = mockFetchOnce(200, { ekonomickeSubjekty: [SUBJECT] });
+    const res = await aresSearchByName("BOHA Automation");
+    expect(Array.isArray(res)).toBe(true);
+    if (Array.isArray(res)) {
+      expect(res).toHaveLength(1);
+      expect(res[0].name).toBe("BOHA Automation s.r.o.");
+      expect(res[0].postal_code).toBe("511 01");
+    }
+    const init = spy.mock.calls[0][1] as RequestInit;
+    expect(JSON.parse(String(init.body))).toMatchObject({
+      obchodniJmeno: "BOHA Automation",
+      pocet: 10,
+    });
+  });
+
+  it("returns [] for a blank query without calling ARES", async () => {
+    const spy = vi.spyOn(globalThis, "fetch");
+    expect(await aresSearchByName("   ")).toEqual([]);
+    expect(spy).not.toHaveBeenCalled();
+  });
+
+  it("maps upstream failure to ares_unavailable", async () => {
+    mockFetchOnce(503);
+    expect(await aresSearchByName("BOHA")).toEqual({
+      error: "ares_unavailable",
+    });
+  });
+});

src/admin/components/AresLookup.tsx

@@ -0,0 +1,153 @@
+import { useState, useRef } from "react";
+import InputAdornment from "@mui/material/InputAdornment";
+import IconButton from "@mui/material/IconButton";
+import Tooltip from "@mui/material/Tooltip";
+import Menu from "@mui/material/Menu";
+import MenuItem from "@mui/material/MenuItem";
+import Typography from "@mui/material/Typography";
+import Box from "@mui/material/Box";
+import CircularProgress from "@mui/material/CircularProgress";
+import { jsonQuery } from "../lib/apiAdapter";
+import { useAlert } from "../context/AlertContext";
+
+/** Normalized company record returned by the /api/admin/ares proxy. */
+export interface AresCompany {
+  ico: string;
+  dic: string | null;
+  name: string;
+  street: string;
+  city: string;
+  postal_code: string;
+  country: string;
+}
+
+interface AresAdornmentProps {
+  /** "ico" looks the query up directly; "name" searches and offers a picker. */
+  mode: "ico" | "name";
+  /** Current value of the host field (IČO or name fragment). */
+  query: string;
+  /** Called with the chosen company — the modal prefills its form from it. */
+  onFill: (company: AresCompany) => void;
+}
+
+/**
+ * "ARES" end-adornment button for the Název/IČO fields of the customer and
+ * supplier modals. IČO mode fetches the subject directly; name mode searches
+ * ARES and shows a result picker (filling straight away on a single hit).
+ * Pass via the TextField's `InputProps.endAdornment`.
+ */
+export default function AresAdornment({
+  mode,
+  query,
+  onFill,
+}: AresAdornmentProps) {
+  const alert = useAlert();
+  const [loading, setLoading] = useState(false);
+  const [results, setResults] = useState<AresCompany[]>([]);
+  const [menuOpen, setMenuOpen] = useState(false);
+  const anchorRef = useRef<HTMLButtonElement | null>(null);
+
+  const trimmed = query.trim();
+  const enabled =
+    mode === "ico"
+      ? /^\d{8}$/.test(trimmed.replace(/\s+/g, ""))
+      : trimmed.length >= 2;
+  const tooltip =
+    mode === "ico"
+      ? enabled
+        ? "Načíst údaje z ARES podle IČO"
+        : "Vyplňte 8místné IČO"
+      : enabled
+        ? "Vyhledat firmu v ARES podle názvu"
+        : "Vyplňte alespoň 2 znaky názvu";
+
+  const lookup = async () => {
+    if (!enabled || loading) return;
+    setLoading(true);
+    try {
+      if (mode === "ico") {
+        const company = await jsonQuery<AresCompany>(
+          `/api/admin/ares/ico/${encodeURIComponent(trimmed.replace(/\s+/g, ""))}`,
+        );
+        onFill(company);
+      } else {
+        const found = await jsonQuery<AresCompany[]>(
+          `/api/admin/ares/search?q=${encodeURIComponent(trimmed)}`,
+        );
+        if (found.length === 0) {
+          alert.error("Žádná firma tohoto názvu nebyla v ARES nalezena");
+        } else if (found.length === 1) {
+          onFill(found[0]);
+        } else {
+          setResults(found);
+          setMenuOpen(true);
+        }
+      }
+    } catch (e) {
+      alert.error(
+        e instanceof Error ? e.message : "Registr ARES je nedostupný",
+      );
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  return (
+    <InputAdornment position="end">
+      <Tooltip title={tooltip}>
+        <span>
+          <IconButton
+            ref={anchorRef}
+            size="small"
+            onClick={lookup}
+            disabled={!enabled || loading}
+            aria-label="Načíst z ARES"
+            edge="end"
+          >
+            {loading ? (
+              <CircularProgress size={16} color="inherit" />
+            ) : (
+              <Typography
+                component="span"
+                sx={{
+                  fontSize: "0.65rem",
+                  fontWeight: 800,
+                  letterSpacing: "0.06em",
+                  color: enabled ? "primary.main" : "text.disabled",
+                  lineHeight: 1,
+                }}
+              >
+                ARES
+              </Typography>
+            )}
+          </IconButton>
+        </span>
+      </Tooltip>
+      <Menu
+        anchorEl={anchorRef.current}
+        open={menuOpen}
+        onClose={() => setMenuOpen(false)}
+      >
+        {results.map((c) => (
+          <MenuItem
+            key={c.ico}
+            onClick={() => {
+              setMenuOpen(false);
+              onFill(c);
+            }}
+          >
+            <Box>
+              <Typography variant="body2" sx={{ fontWeight: 600 }}>
+                {c.name}
+              </Typography>
+              <Typography variant="caption" color="text.secondary">
+                IČO {c.ico}
+                {c.city ? ` · ${c.city}` : ""}
+              </Typography>
+            </Box>
+          </MenuItem>
+        ))}
+      </Menu>
+    </InputAdornment>
+  );
+}

src/admin/pages/OffersCustomers.tsx

@@ -12,6 +12,7 @@ import {
   type CustomField,
 } from "../lib/queries/offers";
 import { useApiMutation } from "../lib/queries/mutations";
+import AresAdornment, { type AresCompany } from "../components/AresLookup";
 import {
   Button,
   Card,
@@ -267,6 +268,21 @@ export default function OffersCustomers() {
     return key;
   };
 
+  // ARES prefill — overwrite the company fields with registry data (the
+  // button is an explicit user action, so overwriting is the expected UX).
+  const fillFromAres = (c: AresCompany) => {
+    setForm((prev) => ({
+      ...prev,
+      name: c.name || prev.name,
+      street: c.street,
+      city: c.city,
+      postal_code: c.postal_code,
+      country: c.country,
+      company_id: c.ico,
+      vat_id: c.dic || "",
+    }));
+  };
+
   const openCreateModal = () => {
     setEditingCustomer(null);
     setForm({
@@ -535,6 +551,15 @@ export default function OffersCustomers() {
               setForm((prev) => ({ ...prev, name: e.target.value }))
             }
             placeholder="Název firmy / jméno"
+            InputProps={{
+              endAdornment: (
+                <AresAdornment
+                  mode="name"
+                  query={form.name}
+                  onFill={fillFromAres}
+                />
+              ),
+            }}
           />
         </Field>
         <Field label="Ulice">
@@ -596,6 +621,15 @@ export default function OffersCustomers() {
                   company_id: e.target.value,
                 }))
               }
+              InputProps={{
+                endAdornment: (
+                  <AresAdornment
+                    mode="ico"
+                    query={form.company_id}
+                    onFill={fillFromAres}
+                  />
+                ),
+              }}
             />
           </Field>
           <Field label="DIČ">

src/routes/admin/ares.ts

@@ -0,0 +1,63 @@
+import { FastifyInstance } from "fastify";
+import { requireAnyPermission } from "../../middleware/auth";
+import { success, error } from "../../utils/response";
+import { aresLookupByIco, aresSearchByName } from "../../services/ares.service";
+
+// Czech messages for the service's token errors.
+const ARES_ERRORS: Record<string, { message: string; status: number }> = {
+  invalid_ico: { message: "IČO musí být 8 číslic", status: 400 },
+  not_found: {
+    message: "Subjekt s tímto IČO nebyl v ARES nalezen",
+    status: 404,
+  },
+  ares_unavailable: {
+    message: "Registr ARES je momentálně nedostupný, zkuste to později",
+    status: 502,
+  },
+};
+
+/**
+ * ARES proxy — the browser cannot call ares.gov.cz directly (CORS + CSP), so
+ * the customer/supplier modals go through these endpoints. Guarded by the
+ * permissions of the two modals that use the prefill (customer editing and
+ * warehouse supplier management); ARES data itself is public.
+ */
+export default async function aresRoutes(fastify: FastifyInstance) {
+  const guard = requireAnyPermission(
+    "customers.create",
+    "customers.edit",
+    "warehouse.manage",
+  );
+
+  // GET /ico/:ico — single subject by IČO
+  fastify.get<{ Params: { ico: string } }>(
+    "/ico/:ico",
+    { preHandler: guard },
+    async (request, reply) => {
+      const result = await aresLookupByIco(request.params.ico);
+      if ("error" in result) {
+        const e = ARES_ERRORS[result.error];
+        return error(reply, e.message, e.status);
+      }
+      return success(reply, result);
+    },
+  );
+
+  // GET /search?q=… — subjects by (part of) business name, max 10
+  fastify.get<{ Querystring: { q?: string } }>(
+    "/search",
+    { preHandler: guard },
+    async (request, reply) => {
+      const q = String(request.query.q ?? "").trim();
+      if (q.length < 2) {
+        return error(reply, "Zadejte alespoň 2 znaky názvu", 400);
+      }
+      const result = await aresSearchByName(q);
+      if ("error" in result && !Array.isArray(result)) {
+        const e = ARES_ERRORS[result.error];
+        return error(reply, e.message, e.status);
+      }
+      return success(reply, result);
+    },
+  );
+}

src/server.ts

@@ -38,6 +38,7 @@ import projectFilesRoutes from "./routes/admin/project-files";
 import warehouseRoutes from "./routes/admin/warehouse";
 import planRoutes from "./routes/admin/plan";
 import aiRoutes from "./routes/admin/ai";
+import aresRoutes from "./routes/admin/ares";
 
 const app = Fastify({
   logger: {
@@ -162,6 +163,7 @@ async function start() {
   await app.register(warehouseRoutes, { prefix: "/api/admin/warehouse" });
   await app.register(planRoutes, { prefix: "/api/admin/plan" });
   await app.register(aiRoutes, { prefix: "/api/admin/ai" });
+  await app.register(aresRoutes, { prefix: "/api/admin/ares" });
 
   // --- Frontend: Vite dev middleware (dev only) ---
   if (!config.isProduction) {

src/services/ares.service.ts

@@ -0,0 +1,134 @@
+/**
+ * ARES (Administrativní registr ekonomických subjektů) lookups — the public
+ * MFČR REST API for Czech company data. No auth required. Used by the
+ * customer/supplier modals to prefill company data from IČO or name.
+ *
+ * Docs: https://ares.gov.cz/swagger-ui (REST v3, ekonomicke-subjekty).
+ * The browser cannot call ares.gov.cz directly (CORS + our CSP connect-src),
+ * so these run server-side behind /api/admin/ares.
+ */
+
+const ARES_BASE = "https://ares.gov.cz/ekonomicke-subjekty-v-be/rest";
+const FETCH_TIMEOUT_MS = 8000;
+
+/** Normalized subject shape consumed by the frontend prefill. */
+export interface AresSubject {
+  ico: string;
+  dic: string | null;
+  name: string;
+  street: string;
+  city: string;
+  postal_code: string;
+  country: string;
+}
+
+interface AresSidlo {
+  nazevStatu?: string;
+  nazevObce?: string;
+  nazevCastiObce?: string;
+  nazevUlice?: string;
+  cisloDomovni?: number;
+  cisloOrientacni?: number;
+  cisloOrientacniPismeno?: string;
+  psc?: number;
+  textovaAdresa?: string;
+}
+
+interface AresEkonomickySubjekt {
+  ico?: string;
+  obchodniJmeno?: string;
+  dic?: string;
+  sidlo?: AresSidlo;
+}
+
+/** "51101" → "511 01" (Czech postal code display format). */
+function formatPsc(psc: number | undefined): string {
+  if (!psc) return "";
+  const s = String(psc);
+  return s.length === 5 ? `${s.slice(0, 3)} ${s.slice(3)}` : s;
+}
+
+/**
+ * Street line from the registered office: "Nádražní 485", Prague-style
+ * orientation numbers become "Ulice 485/12a". Villages without street names
+ * fall back to the municipality part name, then the municipality itself
+ * (matching how ARES itself builds textovaAdresa).
+ */
+function buildStreet(sidlo: AresSidlo): string {
+  const streetName =
+    sidlo.nazevUlice || sidlo.nazevCastiObce || sidlo.nazevObce || "";
+  let num = sidlo.cisloDomovni != null ? String(sidlo.cisloDomovni) : "";
+  if (sidlo.cisloOrientacni != null) {
+    num += `/${sidlo.cisloOrientacni}${sidlo.cisloOrientacniPismeno || ""}`;
+  }
+  return [streetName, num].filter(Boolean).join(" ").trim();
+}
+
+function mapSubject(s: AresEkonomickySubjekt): AresSubject {
+  const sidlo = s.sidlo || {};
+  return {
+    ico: s.ico || "",
+    dic: s.dic || null,
+    name: s.obchodniJmeno || "",
+    street: buildStreet(sidlo),
+    city: sidlo.nazevObce || "",
+    postal_code: formatPsc(sidlo.psc),
+    country: sidlo.nazevStatu || "Česká republika",
+  };
+}
+
+export type AresError = "invalid_ico" | "not_found" | "ares_unavailable";
+
+/** Lookup a single subject by its 8-digit IČO. */
+export async function aresLookupByIco(
+  ico: string,
+): Promise<AresSubject | { error: AresError }> {
+  const normalized = ico.replace(/\s+/g, "");
+  if (!/^\d{8}$/.test(normalized)) return { error: "invalid_ico" };
+
+  try {
+    const response = await fetch(
+      `${ARES_BASE}/ekonomicke-subjekty/${normalized}`,
+      { signal: AbortSignal.timeout(FETCH_TIMEOUT_MS) },
+    );
+    if (response.status === 404) return { error: "not_found" };
+    if (!response.ok) {
+      console.error(`[ares] lookup ${normalized} failed: ${response.status}`);
+      return { error: "ares_unavailable" };
+    }
+    const data = (await response.json()) as AresEkonomickySubjekt;
+    if (!data.ico) return { error: "not_found" };
+    return mapSubject(data);
+  } catch (err) {
+    console.error("[ares] lookup failed:", err);
+    return { error: "ares_unavailable" };
+  }
+}
+
+/** Search subjects by (part of) the business name; returns up to 10 matches. */
+export async function aresSearchByName(
+  name: string,
+): Promise<AresSubject[] | { error: AresError }> {
+  const query = name.trim();
+  if (!query) return [];
+
+  try {
+    const response = await fetch(`${ARES_BASE}/ekonomicke-subjekty/vyhledat`, {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({ obchodniJmeno: query, pocet: 10, start: 0 }),
+      signal: AbortSignal.timeout(FETCH_TIMEOUT_MS),
+    });
+    if (!response.ok) {
+      console.error(`[ares] search "${query}" failed: ${response.status}`);
+      return { error: "ares_unavailable" };
+    }
+    const data = (await response.json()) as {
+      ekonomickeSubjekty?: AresEkonomickySubjekt[];
+    };
+    return (data.ekonomickeSubjekty ?? []).map(mapSubject);
+  } catch (err) {
+    console.error("[ares] search failed:", err);
+    return { error: "ares_unavailable" };
+  }
+}