diff --git a/apps/frontend/src/app/pages/AnalysisArchitectureRedirect.tsx b/apps/frontend/src/app/pages/AnalysisArchitectureRedirect.tsx
new file mode 100644
index 0000000..237eb85
--- /dev/null
+++ b/apps/frontend/src/app/pages/AnalysisArchitectureRedirect.tsx
@@ -0,0 +1,20 @@
+import { useEffect } from 'react';
+import { useNavigate, useParams } from 'react-router-dom';
+import { useAppStore } from '@/app/store/useAppStore';
+
+// A repository-scoped deep link into Architecture (#179): the surface itself
+// is only ever mounted at the top-level `/architecture` route and reads the
+// globally selected repository, so this selects the requested repository
+// first and hands off to that route rather than duplicating the surface.
+export function AnalysisArchitectureRedirect() {
+  const { id } = useParams<{ id: string }>();
+  const navigate = useNavigate();
+  const setActiveRepositoryId = useAppStore((state) => state.setActiveRepositoryId);
+
+  useEffect(() => {
+    if (id) setActiveRepositoryId(id);
+    navigate('/architecture', { replace: true });
+  }, [id, navigate, setActiveRepositoryId]);
+
+  return null;
+}
diff --git a/apps/frontend/src/app/pages/AnalysisPipelinePage.integration.test.tsx b/apps/frontend/src/app/pages/AnalysisPipelinePage.integration.test.tsx
new file mode 100644
index 0000000..8df122d
--- /dev/null
+++ b/apps/frontend/src/app/pages/AnalysisPipelinePage.integration.test.tsx
@@ -0,0 +1,150 @@
+import { act, render, screen } from '@testing-library/react';
+import { MemoryRouter, Route, Routes } from 'react-router-dom';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { useAppStore } from '@/app/store/useAppStore';
+import { backendService } from '@/shared/services/backend';
+import { NetworkError } from '@/shared/services/api';
+import type { Repository } from '@/shared/types';
+import { AnalysisPipelinePage } from './AnalysisPipelinePage';
+
+// Exercises the real hook wired to the real store, unlike the sibling
+// AnalysisPipelinePage.test.tsx which mocks the hook entirely -- #175 was a
+// gap between a hook that transitions correctly in isolation and a page that
+// never actually saw the transition land.
+vi.mock('@/features/repositories/hooks/useRepository', () => ({
+  useRepository: () => ({ repositories: useAppStore((state) => state.repositories) }),
+}));
+
+const repository: Repository = {
+  id: 'repo-1',
+  name: 'sample',
+  source: 'github',
+  size: 10,
+  fileCount: 1,
+  status: 'analysing',
+  analysisStage: null,
+  analysisProgress: 0,
+  uploadedAt: '2026-07-22T08:00:00Z',
+  meta: null,
+  fileTree: [],
+};
+
+function renderPage() {
+  return render(
+    <MemoryRouter initialEntries={['/analysis/repo-1']}>
+      <Routes>
+        <Route path="/analysis/:id" element={<AnalysisPipelinePage />} />
+        <Route path="/repositories/:id" element={<div>Repo Detail Page</div>} />
+      </Routes>
+    </MemoryRouter>,
+  );
+}
+
+describe('AnalysisPipelinePage integration with the real polling hook', () => {
+  beforeEach(() => {
+    useAppStore.setState({ repositories: [repository], analysisRunning: true });
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+    vi.useRealTimers();
+  });
+
+  it('navigates to the analysed repository as soon as the backend reports completed, without a reload', async () => {
+    vi.useFakeTimers();
+    vi.spyOn(backendService, 'startAnalysis').mockResolvedValue({
+      repositoryId: repository.id,
+      status: 'queued',
+      jobId: 'job-1',
+    });
+    vi.spyOn(backendService, 'fetchAnalysisStatus').mockResolvedValue({
+      repositoryId: repository.id,
+      status: 'completed',
+      jobId: 'job-1',
+      stage: 'completed',
+      progress: 100,
+      startedAt: '2026-07-22T08:00:01Z',
+      completedAt: '2026-07-22T08:00:02Z',
+      error: null,
+    });
+
+    // MemoryRouter navigation is a client-side state transition, not a
+    // browser reload -- this test proves the SPA route swap happens on its
+    // own, with no manual reload step anywhere in the flow.
+    renderPage();
+
+    await act(async () => {
+      await vi.advanceTimersByTimeAsync(0);
+    });
+
+    expect(screen.getByText('Repo Detail Page')).toBeInTheDocument();
+  });
+
+  it('renders the Analysis Failed terminal state when the job fails server-side', async () => {
+    vi.useFakeTimers();
+    vi.spyOn(backendService, 'fetchAnalysisStatus').mockResolvedValue({
+      repositoryId: repository.id,
+      status: 'failed',
+      jobId: 'job-1',
+      stage: 'extracting-modules',
+      progress: 35,
+      startedAt: '2026-07-22T08:00:01Z',
+      completedAt: '2026-07-22T08:00:02Z',
+      error: 'Extraction crashed.',
+    });
+
+    renderPage();
+
+    await act(async () => {
+      await vi.advanceTimersByTimeAsync(0);
+    });
+
+    expect(screen.getByText('Analysis Failed')).toBeInTheDocument();
+    expect(screen.getByText('Extraction crashed.')).toBeInTheDocument();
+  });
+
+  it('recovers from a transient poll error into the completed terminal state, without ever showing Analysis Failed', async () => {
+    vi.useFakeTimers();
+    const fetchStatus = vi
+      .spyOn(backendService, 'fetchAnalysisStatus')
+      .mockRejectedValueOnce(new NetworkError('/analysis/repo-1/status'))
+      .mockResolvedValueOnce({
+        repositoryId: repository.id,
+        status: 'running',
+        jobId: 'job-1',
+        stage: 'extracting-modules',
+        progress: 35,
+        startedAt: '2026-07-22T08:00:01Z',
+        completedAt: null,
+        error: null,
+      })
+      .mockResolvedValue({
+        repositoryId: repository.id,
+        status: 'completed',
+        jobId: 'job-1',
+        stage: 'completed',
+        progress: 100,
+        startedAt: '2026-07-22T08:00:01Z',
+        completedAt: '2026-07-22T08:00:02Z',
+        error: null,
+      });
+
+    renderPage();
+
+    await act(async () => {
+      await vi.advanceTimersByTimeAsync(0);
+    });
+    expect(screen.getByText('Connection lost — retrying…')).toBeInTheDocument();
+    expect(screen.queryByText('Analysis Failed')).not.toBeInTheDocument();
+
+    await act(async () => {
+      await vi.advanceTimersByTimeAsync(1000);
+    });
+    await act(async () => {
+      await vi.advanceTimersByTimeAsync(1500);
+    });
+
+    expect(screen.getByText('Repo Detail Page')).toBeInTheDocument();
+    expect(fetchStatus.mock.calls.length).toBeGreaterThanOrEqual(3);
+  });
+});
diff --git a/apps/frontend/src/app/pages/NotFoundPage.tsx b/apps/frontend/src/app/pages/NotFoundPage.tsx
new file mode 100644
index 0000000..2a7c620
--- /dev/null
+++ b/apps/frontend/src/app/pages/NotFoundPage.tsx
@@ -0,0 +1,20 @@
+import { useNavigate } from 'react-router-dom';
+import { Compass } from 'lucide-react';
+import { EmptyState } from '@/shared/components/ui/EmptyState';
+import { PageHeader } from '@/shared/components/ui/PageHeader';
+
+export function NotFoundPage() {
+  const navigate = useNavigate();
+
+  return (
+    <div>
+      <PageHeader title="Page not found" />
+      <EmptyState
+        icon={Compass}
+        title="This page doesn't exist"
+        description="The link may be out of date, or the page may have moved."
+        action={{ label: 'Back to Dashboard', onClick: () => navigate('/') }}
+      />
+    </div>
+  );
+}
diff --git a/apps/frontend/src/app/routes/router.test.tsx b/apps/frontend/src/app/routes/router.test.tsx
new file mode 100644
index 0000000..f10f4a4
--- /dev/null
+++ b/apps/frontend/src/app/routes/router.test.tsx
@@ -0,0 +1,69 @@
+import { render, screen } from '@testing-library/react';
+import { Outlet, RouterProvider } from 'react-router-dom';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { useAppStore } from '@/app/store/useAppStore';
+
+// Bypasses auth/repository-fetch plumbing the same way productSurfaces.test.tsx
+// and accessibility.test.tsx do, so these tests exercise real route matching
+// (#179) without needing a live backend.
+vi.mock('./RequireAuth', () => ({ RequireAuth: () => <Outlet /> }));
+vi.mock('@/shared/components/layout/MainLayout', () => ({ MainLayout: () => <Outlet /> }));
+vi.mock('@/features/repositories/hooks/useRepository', () => ({
+  useRepository: () => ({
+    repositories: [],
+    completedRepositories: [],
+    activeRepository: null,
+    loading: false,
+    error: null,
+    selectRepository: () => undefined,
+    removeRepository: async () => undefined,
+    refresh: () => undefined,
+    retry: () => undefined,
+  }),
+}));
+
+import { createAppRouter } from './router';
+
+const ROUTE_RENDER_TIMEOUT_MS = 3_000;
+let activeRouter: ReturnType<typeof createAppRouter> | null = null;
+
+function renderFreshRoute(path: string) {
+  window.history.replaceState({}, '', path);
+  activeRouter = createAppRouter();
+  return render(<RouterProvider router={activeRouter} />);
+}
+
+describe('deep-linked route reachability (#179)', () => {
+  afterEach(() => {
+    activeRouter?.dispose();
+    activeRouter = null;
+    window.history.replaceState({}, '', '/');
+    useAppStore.setState({ activeRepositoryId: null });
+  });
+
+  it('renders Dashboard directly at /dashboard instead of 404ing', async () => {
+    renderFreshRoute('/dashboard');
+
+    expect(
+      await screen.findByRole('heading', { name: 'Dashboard', level: 1 }, { timeout: ROUTE_RENDER_TIMEOUT_MS }),
+    ).toBeInTheDocument();
+  });
+
+  it('renders Architecture directly at /analysis/{id}/architecture, selecting that repository', async () => {
+    renderFreshRoute('/analysis/repo-42/architecture');
+
+    expect(
+      await screen.findByRole('heading', { name: 'Architecture', level: 1 }, { timeout: ROUTE_RENDER_TIMEOUT_MS }),
+    ).toBeInTheDocument();
+    expect(useAppStore.getState().activeRepositoryId).toBe('repo-42');
+  });
+
+  it('renders a NotFound page instead of crashing on an unknown route', async () => {
+    renderFreshRoute('/this-route-does-not-exist');
+
+    expect(
+      await screen.findByRole('heading', { name: 'Page not found', level: 1 }, { timeout: ROUTE_RENDER_TIMEOUT_MS }),
+    ).toBeInTheDocument();
+    expect(screen.queryByText(/Unexpected Application Error/i)).not.toBeInTheDocument();
+  });
+});
diff --git a/apps/frontend/src/app/routes/router.tsx b/apps/frontend/src/app/routes/router.tsx
index 4c1243b..a6450e9 100644
--- a/apps/frontend/src/app/routes/router.tsx
+++ b/apps/frontend/src/app/routes/router.tsx
@@ -1,4 +1,4 @@
-import { createBrowserRouter } from 'react-router-dom';
+import { createBrowserRouter, Navigate } from 'react-router-dom';
 import { MainLayout } from '@/shared/components/layout/MainLayout';
 import { RequireAuth } from './RequireAuth';
 import { productSurfaceRoutes } from './productSurfaces';
@@ -25,6 +25,12 @@ export function createAppRouter() {
         {
           element: <MainLayout />,
           children: [
+            {
+              // Dashboard's registered path is `/` (see productSurfaces); this
+              // alias keeps the plainer, commonly-guessed URL from 404ing.
+              path: '/dashboard',
+              element: <Navigate to="/" replace />,
+            },
             {
               path: '/repositories/:id',
               lazy: async () => {
@@ -39,7 +45,25 @@ export function createAppRouter() {
                 return { Component: AnalysisPipelinePage };
               },
             },
+            {
+              path: '/analysis/:id/architecture',
+              lazy: async () => {
+                const { AnalysisArchitectureRedirect } = await import('@/app/pages/AnalysisArchitectureRedirect');
+                return { Component: AnalysisArchitectureRedirect };
+              },
+            },
             ...productSurfaceRoutes,
+            {
+              // Catch-all: an unmatched path previously fell through to react-router's
+              // default error boundary ("Unexpected Application Error! 404 Not Found")
+              // instead of a page. This still sits behind RequireAuth, so an
+              // unauthenticated visitor to a bogus path is redirected to /login first.
+              path: '*',
+              lazy: async () => {
+                const { NotFoundPage } = await import('@/app/pages/NotFoundPage');
+                return { Component: NotFoundPage };
+              },
+            },
           ],
         },
       ],
diff --git a/apps/frontend/src/features/analysis/hooks/useAnalysisPipeline.test.ts b/apps/frontend/src/features/analysis/hooks/useAnalysisPipeline.test.ts
index 5dc4fc7..e57462a 100644
--- a/apps/frontend/src/features/analysis/hooks/useAnalysisPipeline.test.ts
+++ b/apps/frontend/src/features/analysis/hooks/useAnalysisPipeline.test.ts
@@ -382,5 +382,36 @@ describe('useAnalysisPipeline', () => {
       expect(hook.result.current.error).toBe('Extraction crashed.');
       expect(hook.result.current.connectionStatus).toBe('connected');
     });
+
+    it('stops polling once a terminal status is observed instead of scheduling another request', async () => {
+      vi.useFakeTimers();
+      const fetchStatus = vi.spyOn(backendService, 'fetchAnalysisStatus').mockResolvedValue({
+        repositoryId: repository.id,
+        status: 'completed',
+        jobId: 'job-1',
+        stage: 'completed',
+        progress: 100,
+        startedAt: '2026-07-22T08:00:01Z',
+        completedAt: '2026-07-22T08:00:02Z',
+        error: null,
+      });
+
+      const hook = renderHook(() => useAnalysisPipeline(repository.id));
+
+      await act(async () => {
+        await vi.advanceTimersByTimeAsync(0);
+      });
+      expect(hook.result.current.jobStatus).toBe('completed');
+      const callsAtCompletion = fetchStatus.mock.calls.length;
+
+      // Advancing well past the poll interval must not trigger another
+      // request -- the loop stops itself on a terminal status rather than
+      // relying on the surrounding effect to tear it down.
+      await act(async () => {
+        await vi.advanceTimersByTimeAsync(1500 * 5);
+      });
+      expect(fetchStatus.mock.calls.length).toBe(callsAtCompletion);
+    });
+
   });
 });
diff --git a/apps/frontend/src/features/analysis/hooks/useAnalysisPipeline.ts b/apps/frontend/src/features/analysis/hooks/useAnalysisPipeline.ts
index a78c152..1b02f77 100644
--- a/apps/frontend/src/features/analysis/hooks/useAnalysisPipeline.ts
+++ b/apps/frontend/src/features/analysis/hooks/useAnalysisPipeline.ts
@@ -43,6 +43,7 @@ export function useAnalysisPipeline(repositoryId: string | undefined) {
 
   const repository = repositories.find((repo) => repo.id === repositoryId) || null;
   const repositoryStatus = repository?.status;
+  const repositoryErrorMessage = repository?.errorMessage;
 
   useEffect(() => {
     pollingGenerationRef.current += 1;
@@ -99,21 +100,20 @@ export function useAnalysisPipeline(repositoryId: string | undefined) {
     setRefreshKey((key) => key + 1);
   }, []);
 
-  // Known limitation: repository identity changes on each poll, so the interval is recreated.
   useEffect(() => {
-    if (!repositoryId || !repository) {
+    if (!repositoryId || !repositoryStatus) {
       setStatus('empty');
       return;
     }
 
-    if (repository.status === 'completed') {
+    if (repositoryStatus === 'completed') {
       setStatus('success');
       return;
     }
 
-    if (repository.status === 'error') {
+    if (repositoryStatus === 'error') {
       setStatus('error');
-      setError(repository.errorMessage || 'Analysis failed.');
+      setError(repositoryErrorMessage || 'Analysis failed.');
       return;
     }
 
@@ -176,6 +176,13 @@ export function useAnalysisPipeline(repositoryId: string | undefined) {
           // A job the API itself reports as failed is a real, terminal outcome --
           // render it immediately, distinct from a dropped connection below.
           applyJobResponse(response);
+
+          // Stop the loop here instead of relying on the surrounding effect to
+          // tear it down on the next render: the poll loop owns its own
+          // lifecycle, so a terminal outcome never schedules another request.
+          if (response.status === 'completed' || response.status === 'failed' || response.status === 'cancelled') {
+            return;
+          }
         } catch (caught) {
           if (cancelled) return;
 
@@ -215,7 +222,7 @@ export function useAnalysisPipeline(repositoryId: string | undefined) {
     applyJobResponse,
     failAnalysis,
     refreshKey,
-    repository,
+    repositoryErrorMessage,
     repositoryId,
     repositoryStatus,
     jobStatus,