@alxhub Could this be a valid solution at db-cache.ts?

export class CacheDatabase implements Database {
  private cacheScope: String; // to distinct between multiple scopes
  private tables = new Map<string, Promise<CacheTable>>();

  constructor(
    private scope: ServiceWorkerGlobalScope,
    private adapter: Adapter
  ) {
    this.cacheScope = this.scope.scope !== './' ? `:${this.scope.scope}` : '';
  }

  delete(name: string): Promise<boolean> {
    if (this.tables.has(name)) {
      this.tables.delete(name);
    }
    return this.scope.caches.delete(`ngsw:db${this.cacheScope}:${name}`);
  }

  list(): Promise<string[]> {
    return this.scope.caches
      .keys()
      .then(keys =>
        keys.filter(key => key.startsWith(`ngsw:db${this.cacheScope}:`))
      );
  }

  open(name: string): Promise<Table> {
    if (!this.tables.has(name)) {
      const table = this.scope.caches
        .open(`ngsw:db${this.cacheScope}:${name}`)
        .then(cache => new CacheTable(name, cache, this.adapter));
      this.tables.set(name, table);
    }
    return this.tables.get(name)!;
  }
}

... but I have to provide different scopes, and the scope will always be ./ by default (and wanted so to intercept all requests down the url path where the service worker script is located) ... maybe get the baseHref somehow? but how can I obtain it safely not doing something like document.getElementsByTagName('base')[0].href?

found this at browser_adapter.ts:

let baseElement: HTMLElement|null = null;
function getBaseElementHref(): string|null {
  if (!baseElement) {
    baseElement = document.querySelector('base') !;
    if (!baseElement) {
      return null;
    }
  }
  return baseElement.getAttribute('href');
}

it is related to the platform that is used and I don't know how to wire this up ...

just get it in a safe way using document if available, sw are only available in the platform browser ...

the CacheDatabase is service worker code, so no dom access there ... I can manipulate the ngsw-worker.js after the build process to include the app/baseHref info in CacheDatabase, by replacing the 3 ngsw:db: entries with ngsw:db:[app-base-href]: ...

I created an issue at the Angular CLI repo too. both are involved somehow, the baseHref option of the CLI needs to be passed to the service worker. I don't think that the service worker is able to do that without information from the CLI?

replacing the ngsw:db: key seems not to work (even replacing the 6 occurences of ngsw: with a unique key does not work, but the distinction is better if you look at the Cache Storage at the dev tools - there are some entries without the ngsw:db prefix if you just replace the 3 occurences of ngsw:db) - the content of the control entry in the CacheDatabase still gets overwritten from another app ...

did some more research, maybe this is helpful somehow. after renaming ngsw: (6 entries in ngsw-worker.js) to ngsw:swAppOne and ngsw:swAppTwo it seems to work, but the Cache Storage seems like to be in an invalid state ... I created a branch in my repo for that, just npm install in sw-app-one and run npm run start-sw and open the pages at sw-app-one and sw-app-two, then have a look into the Cache Storage in the dev tools - the entries ngsw:sw-app-two:db:control and ngsw:sw-app-one:db:control have the same values for assignments, latest and manifests - an image of it here.

Afterwards I also renamed the entries assigments to assigmentsSwAppOne and so on (the other way round in the commit, was to create a reproduction of the weird state). The result looks clean now, with all the renaming. but still weird somehow, I also refreshed the cache in the dev tools ...