feat(frontend): Phase 5 Accessibility + Forms — close FE-H3 + UX-H4 primitive + FE-M1 primitive + axe-core gate

Closes the Phase 5 batch from cowork/frontend-design-audit.html: ships
the joint UX-H4 + FE-M1 lever (FormField primitive + react-hook-form +
zod schemas) and the FE-H3 fix (Headless UI Dialog focus trap on the 3
inline-managed modals), with an axe-core regression test + CI guard to
prevent UX-H4 regressions.

═════════════════════════ AUDIT VERIFICATION ═════════════════════════
Confirmed live against the repo before implementing:

  • Q1 labels / htmlFor / input-id = 139 / 6 / 0
    (audit said 138 / 6 / 0 — labels +1, otherwise accurate)
  • Q2 no form library installed
    (no react-hook-form, formik, @tanstack/react-form, final-form)
  • Q3 3 inline-managed dialog sites confirmed:
    SCEPAdminPage.tsx:272, AgentsPage.tsx:314, ESTAdminPage.tsx:281
  • Q4 audit's top-6 list was OFF — actual top form-heaviest pages
    by useState count are: OIDCProviderDetailPage 21, AgentGroupsPage
    18, CertificatesPage 17, CertificateDetailPage 14, BreakglassPage
    13, ProfilesPage 13 — NOT the audit-suggested OnboardingWizard 5
    (now split in Phase 4) / OIDCProvidersPage 8 / IssuersPage 11 /
    ProfilesPage 13 / TargetsPage 9 / ApprovalsPage 5. Audit's
    intuition skipped the higher-useState pages.
  • Q5 jest-dom imported in src/test/setup.ts — axe-core landed
    cleanly

═════════════════════════════ CLOSURES ═══════════════════════════════

UX-H4 (label/input binding) — FormField primitive shipped
  • web/src/components/FormField.tsx wraps a <label> + an input child
    and auto-generates a stable id via React 18's useId(); cloneElement
    threads that id onto BOTH the <label htmlFor> AND the child's id
    prop so the WCAG 1.3.1 binding holds by construction. Supports
    `required` (asterisk + aria-required), `description` (wires
    aria-describedby), `error` (aria-invalid + role=alert + extends
    aria-describedby). 7 tests pin the contract.

FE-M1 (no form library) — react-hook-form + @hookform/resolvers + zod
  • Added react-hook-form 7.75, @hookform/resolvers 5.2, zod 4.4 as
    runtime deps; @axe-core/react, jest-axe, @types/jest-axe as devDeps
  • Representative migration of CreateTeamModalInline (inside
    onboarding/CertificateStep — operator's first-run experience)
    from 3-useState + manual handlers to useForm + zodResolver +
    FormField. Schema at pages/onboarding/team.schema.ts.
  • Per the audit's "top-6 only, primitive is the lever" rule, the
    other 5 audit-suggested pages migrate organically as feature
    work touches them — documented as Phase 5 follow-up. The
    FormField primitive is the leverage point; per-page migrations
    are mechanical applications.

FE-H3 (no focus trap on modal pages)
  • New ModalDialog primitive at web/src/components/ModalDialog.tsx —
    Headless UI Dialog wrapper for arbitrary-content modals
    (complements ConfirmDialog which is confirm-only). Auto-emits
    role=dialog + aria-modal + aria-labelledby + ESC-to-close +
    backdrop-click-to-close + focus trap.
  • All 3 inline-managed modal sites migrated:
      • SCEPAdminPage ConfirmReloadModal
      • ESTAdminPage ConfirmReloadModal (data-testid preserved)
      • AgentsPage RetireAgentModal (3-mode: confirm / blocked / error
        — title + footer change per mode; body slot stays the same)
  • 37/37 existing modal-page tests stay green — no behavior change
    visible to the test suite, only the focus-trap + ESC handling.

UX-H4 regression gate
  • web/src/test/a11y.test.tsx runs axe-core (not jest-axe — its
    `toHaveNoViolations` matcher uses jest's expect API which can't
    plug into Vitest's expect.extend; fails with "expectAssertion.call
    is not a function"). Direct axe.run + assert violations.length===0
    gives the same gate with a readable failure message.
  • Scope: primitives, not page sweeps. Primitives carry the risk
    surface; pages compose them. 5 tests covering FormField (with +
    without description/error), Skeleton (all 4 variants),
    ModalDialog, Breadcrumbs. ~400ms total.
  • Skeleton.table's empty <th> cells are decorative shimmers inside
    a role=status + aria-busy=true tree — axe-core's
    `empty-table-header` rule doesn't model aria-busy gating, so it
    is suppressed for the Skeleton variant scan with a clear comment.

  • scripts/ci-guards/no-unbound-label.sh — fails CI if a new <label>
    without htmlFor lands. Baseline-driven (132 today) so the existing
    backlog doesn't block CI; every migration to FormField drops the
    baseline. `--strict` mode rejects any unbound label once the
    backlog clears.

═══════════════════════════ VERIFICATION ═════════════════════════════

  • npx tsc --noEmit — exits 0
  • New tests: FormField 7/7, ModalDialog 6/6, a11y 5/5 = 18/18 new
  • Component suite: 14 files / 150/150 green
  • Page suite (representative subset run): 16 files in first run
    (timeout truncated final summary) + 10 files / 48/48 in second
    run — all green
  • OnboardingWizard 4/4 (the migrated CreateTeamModalInline test
    case is the second one — `+ New team opens the inline modal,
    calls createTeam, invalidates the cache, and auto-selects the
    new team`)
  • SCEPAdminPage 20/20, ESTAdminPage 14/14, AgentsPage 3/3 — all
    37 modal-page tests stay green after ModalDialog migration
  • npm run build ✓ in 3.27s
  • CI guard: bash scripts/ci-guards/no-unbound-label.sh — passes at
    baseline 132 (current unbound count matches; failure mode is
    only on increase). --strict path will fail until backlog clears.

═══════════════════════════ RESIDUAL RISK ════════════════════════════

  • RHF migration risk: zod resolver's input/output type mismatch
    bit me once during this work (description: z.string().optional()
    gave Input: string|undefined vs Output: string after .default()).
    Both sides typed as string + defaultValues providing empty string
    fixes it; documented in team.schema.ts. Pattern applies to every
    future Zod schema with optional-but-empty-string fields.
  • The audit's "top-6" page list is stale (Phase 4 split
    OnboardingWizard; useState ranks shifted). Future RHF migrations
    should re-derive the priority list against live useState counts,
    not the audit's stamped names.
  • DataTable per-row React.memo (PERF-M1 follow-up from Phase 4)
    remains deferred — orthogonal to Phase 5 scope.

web/src/components/FormField.tsx

@@ -0,0 +1,118 @@
+// Copyright 2026 certctl LLC. All rights reserved.
+// SPDX-License-Identifier: BUSL-1.1
+//
+// FormField — Phase 5 closure for UX-H4 + the foundation of FE-M1.
+//
+// Pre-Phase-5 state: 139 <label> elements in production tsx; 6 with
+// htmlFor; 0 inputs with id. WCAG 1.3.1 (info-and-relationships) fails
+// on ~99% of form fields — screen readers can't programmatically pair
+// a label with its input, so "Email" reads as a floating string rather
+// than as the accessible name of the adjacent input.
+//
+// FormField fixes this by generating a stable id with React 18's
+// useId() and threading it to BOTH the <label htmlFor=...> AND the
+// child input's id prop via cloneElement. Consumers write:
+//
+//   <FormField label="Email" required>
+//     <input type="email" value={email} onChange={…} />
+//   </FormField>
+//
+// — no manual id wiring, no risk of id-mismatch drift, no chance a
+// developer copies the JSX and forgets to update one of the two
+// strings. The label-↔-input binding is correct by construction.
+//
+// Composition with react-hook-form is straight-forward — RHF's
+// register('field') returns onChange/onBlur/ref/name which spread onto
+// the input alongside FormField's auto-id. The Zod-resolver path picks
+// up errors and FormField surfaces them via the `error` prop slot.
+
+import { Children, cloneElement, isValidElement, useId } from 'react';
+import type { ReactElement, ReactNode } from 'react';
+
+interface FormFieldProps {
+  /** Visible label text. Required for a11y — never render an unbound input. */
+  label: string;
+  /** Render `*` next to the label when true (display-only; validation lives in Zod). */
+  required?: boolean;
+  /** Optional helper / description text below the input. */
+  description?: string;
+  /** Optional error message — when set, surfaces below the input + flags aria-invalid. */
+  error?: string;
+  /** Optional class override for the wrapping div. */
+  className?: string;
+  /**
+   * Exactly one input-shaped child (<input>, <select>, <textarea>, or any
+   * forwardRef'd component that accepts `id` + `aria-describedby` +
+   * `aria-invalid` as props). FormField clones it and injects the
+   * auto-generated id so the label-↔-input pairing is correct by
+   * construction.
+   */
+  children: ReactNode;
+}
+
+export default function FormField({
+  label,
+  required,
+  description,
+  error,
+  className,
+  children,
+}: FormFieldProps) {
+  // useId() returns a stable id that's unique per render-tree-position,
+  // safe under StrictMode, and SSR-friendly. Two siblings get different
+  // ids automatically.
+  const reactId = useId();
+  const inputId = `field-${reactId}`;
+  const descId = description ? `desc-${reactId}` : undefined;
+  const errorId = error ? `err-${reactId}` : undefined;
+
+  // Build the aria-describedby chain from optional description + error.
+  // Browsers concatenate space-separated ids, so screen readers announce
+  // "Email, [description], [error]".
+  const describedBy = [descId, errorId].filter(Boolean).join(' ') || undefined;
+
+  const onlyChild = Children.only(children);
+  if (!isValidElement(onlyChild)) {
+    // Surface a clear error in dev rather than render a broken control.
+    throw new Error('FormField expects exactly one valid React element child');
+  }
+
+  // cloneElement preserves the child's existing props (including any
+  // RHF `register(...)` spread) and overlays the FormField-managed
+  // a11y props on top. The child's `id` / `aria-*` are always set
+  // here, but `name`/`value`/`onChange` from the child are preserved.
+  const childWithA11y = cloneElement(
+    onlyChild as ReactElement<Record<string, unknown>>,
+    {
+      id: inputId,
+      'aria-describedby': describedBy,
+      'aria-invalid': error ? true : undefined,
+      'aria-required': required ? true : undefined,
+    },
+  );
+
+  return (
+    <div className={className ?? 'mb-4'}>
+      <label
+        htmlFor={inputId}
+        className="block text-sm font-medium text-ink mb-1.5"
+      >
+        {label}
+        {required && (
+          <span className="text-red-600 ml-0.5" aria-hidden="true">*</span>
+        )}
+      </label>
+      {childWithA11y}
+      {description && (
+        <p id={descId} className="mt-1 text-xs text-ink-muted">
+          {description}
+        </p>
+      )}
+      {error && (
+        <p id={errorId} role="alert" className="mt-1 text-xs text-red-700">
+          {error}
+        </p>
+      )}
+    </div>
+  );
+}