fix: resolve all 28 findings from the 2026-06-12 full audit (TDD-pinned)

Critical (data integrity):
- warehouse inventory confirm: throw (not return) inside $transaction so a
  failed deficit line rolls back the surplus corrective receipt — retries
  no longer accumulate phantom stock
- warehouse issue confirm: validate batches against the COMBINED quantity
  of all lines (duplicate FIFO-resolved lines drove batches negative)
- attendance delete: restore vacation_used/sick_used for the deleted day
  (in-transaction, clamped at 0)

High:
- auth refresh: terminated sessions (replaced_at only) get a plain 401 —
  the theft branch (family revocation) now fires only on replaced_by_hash
- POST /users strips role_id for non-admin callers (mirrors PUT guard)
- issued-order transition flushes unsaved edits via the full save payload
  when dirty; server contract (items+status in one PUT) pinned
- received-invoices list: usePaginatedQuery + pager (rows 26+ unreachable)
- received-invoice dates: nullableIsoDateString + NaN guard before NAS save
  (Czech-format dates corrupted month/year, orphaned NAS files)
- leave approval skips Czech public holidays and books each calendar year's
  hours against its own balance (mirrors createLeave)

Medium/Low (classes):
- 52 Zod caps aligned to DB column widths across 7 schemas (over-cap input
  500ed at Prisma instead of a Czech 400)
- FK pre-validation: projects update + warehouse receipts/issues return
  Czech 400s instead of P2003 500s
- invoice PDF degrades gracefully when the CNB rate is unavailable
  (recap omitted instead of 500 + lost NAS archival)
- date boundaries: local-day filters (warehouse lists/reports, audit-log),
  @db.Date coercion on invoice dates
- plan updateEntry re-checks the per-cell cap (self-excluding)
- {id} tiebreaks on customers/received-invoices/warehouse-items sorts;
  /items honors the client sort param
- htmlToPdf relaunches once when the shared browser died mid-render
- offer number release parses the year from the document number (cross-year
  finalize+delete left permanent sequence gaps)
- trips/vehicles km fields integer-coerced; AI budget regated to
  settings.company|settings.system; Settings System tab no longer clobbers
  Firma numbering patterns; draft invoices hide the dead PDF button;
  dashboard quick-trip invalidates ["vehicles"]; TOTP secret cap 64;
  audit-log + invoice month buckets day-shift fixes

Docs: corrected the stale "Chromium has no CSS margin-box footers" claim
(html-to-pdf.ts + CLAUDE.md — margin boxes render since Chrome 131); audit
report M3 withdrawn accordingly.

~65 new pinning tests; every finding reproduced RED against the real test
DB before its fix. Suite: 58 files / 634 tests green.

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

src/__tests__/ai-budget-permission.test.ts

@@ -0,0 +1,137 @@
+import { describe, it, expect, beforeAll, afterAll } from "vitest";
+import Fastify from "fastify";
+import cookie from "@fastify/cookie";
+import rateLimit from "@fastify/rate-limit";
+import jwt from "jsonwebtoken";
+import prisma from "../config/database";
+import { config } from "../config/env";
+import { securityHeaders } from "../middleware/security";
+import aiRoutes from "../routes/admin/ai";
+import { getBudgetUsd, setBudgetUsd } from "../services/ai.service";
+
+/**
+ * Pinning test for audit finding L8a: the company-wide AI monthly budget must
+ * NOT be mutable by an ordinary ai.use holder (budget_usd=0 is a company-wide
+ * AI DoS; a huge value removes the cost cap). It is a company setting —
+ * settings.company / settings.system / admin only.
+ */
+
+const N = "ai_budget_perm_";
+const stamp = Date.now().toString(36);
+
+let app: ReturnType<typeof Fastify>;
+let adminToken: string;
+let aiUserToken: string;
+let aiRoleId: number;
+let savedBudget: number;
+
+function token(user: { id: number; username: string; roleName: string }) {
+  return jwt.sign(
+    { sub: user.id, username: user.username, role: user.roleName },
+    config.jwt.secret,
+    { expiresIn: "15m" },
+  );
+}
+
+async function cleanup() {
+  await prisma.users.deleteMany({ where: { username: { startsWith: N } } });
+  const roles = await prisma.roles.findMany({
+    where: { name: { startsWith: N } },
+    select: { id: true },
+  });
+  const roleIds = roles.map((r) => r.id);
+  if (roleIds.length > 0) {
+    await prisma.role_permissions.deleteMany({
+      where: { role_id: { in: roleIds } },
+    });
+    await prisma.roles.deleteMany({ where: { id: { in: roleIds } } });
+  }
+}
+
+beforeAll(async () => {
+  await cleanup();
+  savedBudget = await getBudgetUsd();
+
+  app = Fastify({ logger: false });
+  await app.register(cookie);
+  await app.register(rateLimit, { max: 1000, timeWindow: "1 minute" });
+  app.addHook("onRequest", securityHeaders);
+  await app.register(aiRoutes, { prefix: "/api/admin/ai" });
+
+  const admin = await prisma.users.findFirst({
+    where: { roles: { name: "admin" } },
+  });
+  if (!admin) throw new Error("Test setup: admin user not found");
+  adminToken = token({
+    id: admin.id,
+    username: admin.username,
+    roleName: "admin",
+  });
+
+  // Ordinary ai.use holder — may chat, must NOT control the budget.
+  const role = await prisma.roles.create({
+    data: { name: `${N}aiuse_${stamp}`, display_name: "AI Use Only" },
+  });
+  aiRoleId = role.id;
+  const perm = await prisma.permissions.findFirst({
+    where: { name: "ai.use" },
+  });
+  if (!perm) throw new Error("Test setup: ai.use permission missing");
+  await prisma.role_permissions.create({
+    data: { role_id: aiRoleId, permission_id: perm.id },
+  });
+  const user = await prisma.users.create({
+    data: {
+      username: `${N}user_${stamp}`,
+      email: `${N}${stamp}@test.local`,
+      password_hash:
+        "$2a$10$invalidinvalidinvalidinvalidinvalidinvalidinvalidinvali",
+      first_name: "AiUse",
+      last_name: "Only",
+      is_active: true,
+      role_id: aiRoleId,
+    },
+  });
+  aiUserToken = token({
+    id: user.id,
+    username: user.username,
+    roleName: role.name,
+  });
+});
+
+afterAll(async () => {
+  await setBudgetUsd(savedBudget); // restore whatever the test DB had
+  if (app) await app.close();
+  await cleanup();
+  await prisma.$disconnect();
+});
+
+describe("PUT /ai/budget permission gate (audit L8a)", () => {
+  it("rejects an ordinary ai.use holder with 403", async () => {
+    const res = await app.inject({
+      method: "PUT",
+      url: "/api/admin/ai/budget",
+      headers: {
+        Authorization: `Bearer ${aiUserToken}`,
+        "Content-Type": "application/json",
+      },
+      payload: { budget_usd: 0 },
+    });
+    expect(res.statusCode).toBe(403);
+    // ...and the budget must be untouched.
+    expect(await getBudgetUsd()).toBe(savedBudget);
+  });
+
+  it("allows an admin to set the budget", async () => {
+    const res = await app.inject({
+      method: "PUT",
+      url: "/api/admin/ai/budget",
+      headers: {
+        Authorization: `Bearer ${adminToken}`,
+        "Content-Type": "application/json",
+      },
+      payload: { budget_usd: savedBudget },
+    });
+    expect(res.statusCode).toBe(200);
+  });
+});