refactor(auth): share the actor-agnostic route guards (ADR-C-006)

authGuard and capabilityGuard were duplicated byte-for-byte across both
apps, along with their specs — 57 of the 211 duplicated lines BL-002
measured in the two auth contexts, the largest block after session.store.ts.

They are not actor-specific. They ask "is anyone logged in" and "may they do
X", never "who are you or how did you get here". ADR-0002 §3's non-sharing
decision scopes to identity and login flow — Principal, DigiD vs employee
SSO — and a route guard is neither; §Consequences names auth.guard.ts only
as a seam that localises the change, not as something that must be
duplicated.

Moves both to libs/shared/src/application/auth.guard.ts, reading SESSION_PORT
instead of an app-local SessionStore. The port gains one member,
isAuthenticated: Signal<boolean> — free, because both SessionStores already
expose exactly that (session.store.ts:40) and both apps already register
{ provide: SESSION_PORT, useExisting: SessionStore }. The seam existed; it
was just narrower than what it already carried.

Each app keeps a re-export at @auth/auth.guard so app.routes.ts is untouched
— routing asks the auth context for its guards, which is the direction the
boundary should read. The two identical specs collapse into one, plus a case
asserting the guard resolves through the port.

Deliberately NOT merged: session.store.ts, session.ts, digid.adapter.ts,
login-form.component.ts, login.page.ts. Those are identical only because
ADR-C-004 (Session -> Principal) was never executed. Merging them would make
a citizen DigiD/BSN login the backoffice's shared login.

Measured with tools/baseline-scan.mjs: ssp/auth duplicated lines 211 -> 151,
bhp/auth 86.8% -> 82.5%, repo-wide 7.1% -> 6.6%. Both guard clone pairs drop
out of the top-clones list. What remains is exactly the three files
ADR-C-004 should differentiate.

behaviour-spec.mdx regenerated (the spec moved libraries).

Verified: lint, typecheck, dep:check (0 violations, 224 modules), prettier,
ng build --localize for both apps, and 407 tests passing across all four
projects.

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

libs/shared/src/application/auth.guard.spec.ts

@@ -0,0 +1,69 @@
+import { TestBed } from '@angular/core/testing';
+import { Router } from '@angular/router';
+import { describe, it, expect, vi } from 'vitest';
+import { AccessStore } from '@shared/application/access.store';
+import { SESSION_PORT } from '@shared/application/session.port';
+import { authGuard, capabilityGuard } from './auth.guard';
+
+type Opts = {
+  authed: boolean;
+  can?: (c: string) => boolean;
+  whenReady?: () => Promise<void>;
+};
+
+function setup({ authed, can = () => false, whenReady = () => Promise.resolve() }: Opts) {
+  const createUrlTree = vi.fn((cmds: string[]) => ({ tree: cmds }));
+  const readySpy = vi.fn(whenReady);
+  TestBed.configureTestingModule({
+    providers: [
+      { provide: SESSION_PORT, useValue: { isAuthenticated: () => authed } },
+      { provide: AccessStore, useValue: { whenReady: readySpy, can } },
+      { provide: Router, useValue: { createUrlTree } },
+    ],
+  });
+  return { createUrlTree, readySpy };
+}
+
+// The guards ignore their (route, state) args; cast to call with none.
+const call = <T>(fn: unknown) => TestBed.runInInjectionContext(() => (fn as () => T)());
+
+describe('authGuard', () => {
+  it('allows an authenticated user', () => {
+    setup({ authed: true });
+    expect(call(authGuard)).toBe(true);
+  });
+
+  it('redirects an anonymous user to /login', () => {
+    const { createUrlTree } = setup({ authed: false });
+    expect(call(authGuard)).toEqual({ tree: ['/login'] });
+    expect(createUrlTree).toHaveBeenCalledWith(['/login']);
+  });
+});
+
+describe('capabilityGuard', () => {
+  const guard = () => capabilityGuard('stamdata:edit');
+
+  it('waits for /me, then allows an entitled admin', async () => {
+    const { readySpy } = setup({ authed: true, can: (c) => c === 'stamdata:edit' });
+    await expect(call<Promise<unknown>>(guard())).resolves.toBe(true);
+    expect(readySpy).toHaveBeenCalledOnce(); // it awaited caps before deciding
+  });
+
+  it('sends an authenticated-but-unentitled user to /dashboard (not a login loop)', async () => {
+    setup({ authed: true, can: () => false });
+    await expect(call<Promise<unknown>>(guard())).resolves.toEqual({ tree: ['/dashboard'] });
+  });
+
+  it('redirects an anonymous user to /login without waiting for caps', async () => {
+    const { readySpy } = setup({ authed: false, can: () => true });
+    await expect(call<Promise<unknown>>(guard())).resolves.toEqual({ tree: ['/login'] });
+    expect(readySpy).not.toHaveBeenCalled();
+  });
+
+  // The guard reads SESSION_PORT, never a concrete SessionStore — that is what lets one
+  // copy serve both apps while ADR-0002 §3 keeps their `auth` contexts separate.
+  it('reads authentication through the port, not an app-local store', () => {
+    setup({ authed: true });
+    expect(TestBed.inject(SESSION_PORT).isAuthenticated()).toBe(true);
+  });
+});

libs/shared/src/application/auth.guard.ts

@@ -0,0 +1,48 @@
+import { inject } from '@angular/core';
+import { CanActivateFn, Router } from '@angular/router';
+import { AccessStore } from '@shared/application/access.store';
+import { SESSION_PORT } from '@shared/application/session.port';
+import { Capability } from '@shared/domain/capability';
+
+/**
+ * Route guards, shared by both apps (ADR-C-006).
+ *
+ * These are deliberately **not** part of the `auth` context that ADR-0002 §3 keeps
+ * duplicated per app. That decision scopes to *identity and login flow* — `Principal`,
+ * DigiD vs. employee SSO. A route guard is neither: it asks only "is anyone logged in"
+ * and "may they do X", never "who are you or how did you get here". Both questions are
+ * answered through seams that already live here — `SESSION_PORT` and `AccessStore` — so
+ * the guards never see an actor type and have nothing to diverge on.
+ *
+ * Each app re-exports these from its own `auth/auth.guard.ts`, so `app.routes.ts` keeps
+ * importing `@auth/auth.guard` and the context boundary reads unchanged.
+ */
+
+/** Route guard: only let authenticated users in; otherwise redirect to /login. */
+export const authGuard: CanActivateFn = () => {
+  const session = inject(SESSION_PORT);
+  const router = inject(Router);
+  return session.isAuthenticated() ? true : router.createUrlTree(['/login']);
+};
+
+/**
+ * Route guard factory (PRD-0002 §6): authenticated AND holding `capability`, else
+ * redirect. Used by the admin pages (`/brief/huisstijl`, `/beheer/stamdata`).
+ *
+ * **Async on purpose:** `can()` is deny-by-default, so it must not be read while `/me`
+ * is still loading — it would deny an entitled admin and bounce them. We await
+ * `AccessStore.whenReady()` (caps resolved) before deciding. An unauthenticated user
+ * goes to `/login`; an authenticated-but-unentitled user goes to `/dashboard` (they're
+ * logged in, just not allowed here — no re-login loop). The backend re-enforces
+ * regardless (403); this guard is the UX pre-gate.
+ */
+export function capabilityGuard(capability: Capability): CanActivateFn {
+  return async () => {
+    const session = inject(SESSION_PORT);
+    const access = inject(AccessStore);
+    const router = inject(Router);
+    if (!session.isAuthenticated()) return router.createUrlTree(['/login']);
+    await access.whenReady();
+    return access.can(capability) ? true : router.createUrlTree(['/dashboard']);
+  };
+}

libs/shared/src/application/session.port.ts

@@ -8,6 +8,8 @@ import { InjectionToken, Signal } from '@angular/core';
  */
 export interface SessionPort {
   readonly session: Signal<{ naam: string } | null>;
+  /** Whether anyone is logged in. The shared route guards read only this — never who. */
+  readonly isAuthenticated: Signal<boolean>;
   logout(): void;
 }