PWA Runtime Model

A PWA is still a website. Installation adds operating-system launch surfaces, but the runtime is the browser engine plus origin-scoped storage and service worker control.

flowchart LR
    user[User] --> installed[Installed app window]
    user --> browser[Browser tab]

    subgraph client["Client device"]
        direction TB
        installed --> app[Web app]
        browser --> app
        app --> manifest[Manifest]
        app --> sw[Service worker]
        sw --> cache[(Cache Storage)]
        app --> idb[(IndexedDB)]
        sw --> idb
    end

    subgraph origin["Web origin"]
        direction TB
        server[App server or static host]
        api[API server]
    end

    subgraph platform["Platform services"]
        direction TB
        push[Push service]
        os[OS integration]
    end

    sw --> server
    app --> api
    push --> sw
    manifest --> os

What to notice:

• The manifest describes app identity and install presentation. It does not execute code.
• The service worker sits between controlled pages and network requests. It can also receive push and sync events.
• Cache Storage stores request/response resources. IndexedDB stores app data.
• Installed windows and browser tabs are both web clients. Scope and origin still matter.

Runtime Boundaries

Gotcha: Do not keep critical state in service worker globals. Browsers can terminate and restart service workers. Persist state in IndexedDB or send it to the server.