---
title: "Real-life scenario: OpsCanvas"
chapter: "19"
---

# Real-life scenario: OpsCanvas

OpsCanvas is a global operations portal for logistics teams. Operators monitor
shipments, resolve exceptions, edit schedules, and approve high-risk changes on
desktop and rugged tablets. Public status pages need SEO; the authenticated
control room does not.

## Product requirements

- 50,000 live shipments with server filtering and virtualized results;
- deep links to every exception and preserved URL filters;
- real-time status events without losing current UI state;
- accessible keyboard-first dialogs and command palette;
- tenant and region authorization enforced by APIs;
- offline-aware read state and explicit mutation failure;
- English, Arabic/RTL, and Japanese;
- staged upgrades with observable performance budgets.

## Feature architecture

```text
app-shell/
shipments/
  domain/
  data-access/
  feature-board/
  feature-detail/
  ui/
exceptions/
approvals/
status-public/
design-system/
```

Each feature route lazy-loads and owns a scoped store. URL signals own filters
that must survive sharing. Component signals own panel and selection state.
HttpClient/httpResource owns server reads; RxJS owns the live event stream.

## State flow

The shipment board derives visible rows from route filters plus paged server
results. A websocket Observable merges validated events into the feature store.
`computed` produces counters and selected detail. No effect copies one signal
into another.

## Tailwind and design tokens

Tailwind 4.3 defines semantic CSS variables for surface, text, action, warning,
danger, focus, density, and logical spacing. Container queries let the detail
panel adapt when docked. RTL uses logical properties rather than left/right
assumptions.

## Flowbite ownership

Flowbite 4 provides starting markup/themes for dropdowns, datepicker, and
drawers. OpsCanvas wraps each imperative behavior in an Angular directive that
initializes after render, records its instance, exposes semantic events, and
destroys on route removal. The approval dialog uses CDK Overlay and focus tools
because security confirmation, trap, restoration, and nested overlays need
Angular-native control.

## Rendering strategy

Public shipment status routes use SSG or SSR with hydration. Authenticated
control-room routes use CSR behind secure APIs. Flowbite imports only in browser
wrappers. User-specific resources are never serialized into shared cacheable
HTML.

## Command workflow

“Approve reroute” has:

1. backend-fetched permission and current version;
2. accessible confirmation with reason;
3. one in-flight submission using `exhaustMap` or explicit state;
4. idempotency key and optimistic concurrency version;
5. 409 conflict retaining entered reason;
6. audit correlation ID;
7. success updating server state and announcing completion.

## Testing evidence

- pure tests for rules and DTO parsing;
- Vitest component tests for loading, empty, denied, error, and success;
- HTTP tests for auth, conflict, and cancellation;
- Playwright for deep links, keyboard dialogs, mobile drawer scrolling, RTL,
  hydration, and expired sessions;
- axe/accessibility review plus manual screen reader and keyboard checks;
- bundle budgets and p75 Core Web Vitals in release gates.

## Deployment

CI uses a supported Node line, Angular/CLI 22.1, TypeScript 6.0, locked npm
dependencies, Tailwind 4.3, and Flowbite 4.0. Build once into an immutable image.
Runtime configuration is validated before bootstrap. Hashed assets cache
immutably; the SPA/SSR document does not become stale. A canary cohort proves
errors, latency, and user outcomes before full rollout.

## Failure walkthrough

If Flowbite initializes twice after navigation, dropdown listeners fire twice.
The wrapper registry detects an existing instance, destroys during route
cleanup, and a browser test proves one event per action. If hydration sees
client-only DOM mutation, initialization moves to an after-render browser hook
rather than skipping hydration for the whole page.

## Glossary and abbreviations

| Term | Plain meaning |
|---|---|
| CSR / SSR / SSG | Client / request-time server / build-time rendering |
| DI | Dependency injection |
| Signal / computed | Tracked value / derived tracked value |
| Resource | Signal-oriented managed asynchronous value |
| RxJS / Observable | Reactive Extensions / values over time |
| CVA | ControlValueAccessor for custom form controls |
| CDK | Angular Component Dev Kit |
| CWV | Core Web Vitals |
| LCP / CLS / INP | Loading, layout stability, interaction metrics |
| CSP / XSS / CSRF | Browser security policy / script injection / forged request |
| RTL / i18n | Right-to-left layout / internationalization |
| DTO | Data transfer object |
| E2E | End-to-end browser test |
| RUM | Real-user monitoring |
| SBOM | Software bill of materials |

## Official references

- [Angular release and support policy](https://angular.dev/reference/releases)
- [Angular version compatibility](https://angular.dev/reference/versions)
- [Angular signals](https://angular.dev/guide/signals)
- [Angular zoneless guide](https://angular.dev/guide/zoneless)
- [Angular SSR and hydration](https://angular.dev/guide/performance)
- [Angular testing](https://angular.dev/guide/testing)
- [Tailwind CSS 4.3](https://tailwindcss.com/blog/tailwindcss-v4-3)
- [Flowbite Angular guide](https://flowbite.com/docs/getting-started/angular/)
- [Flowbite changelog](https://flowbite.com/docs/getting-started/changelog/)

## Final Feynman challenge

Trace one reroute approval from URL and component, through signals, form,
dialog, HTTP interceptor, backend conflict, state update, Tailwind/Flowbite
rendering, accessibility announcement, telemetry, and rollback.