Add tenant user assignment

[raphaelblum]

Description

Adding simple assignment of users to tenants. This PR only handles assignment, but not the actual handling that users see what they should see.

Acceptance criteria

• I have verified if my change requires an example
• I have verified if my change requires a changeset
• I have verified if my change requires screenshots/screencasts

Screenshots/screencasts

Screen.Recording.2025-12-16.at.14.50.38.mov

Further information

• Task: https://vivid-planet.atlassian.net/browse/COM-2704

[johnnyomair]

The TenantsModule shouldn't provide UserService, because it isn't part of this module.

[raphaelblum]

Do you know how I can do that ?

Problem:
The auth.module is configurable with forRoot. So a simple import in the imports array does not work.

Current solutions I can think of:

• making AuthModule global
• Making a UserModule which exports the UserService and imports it in AuthModule and Tenants.module (not sure if this would work with the auth.module)

Or like that, found that in a project:

export class XXXModule {
    private static instance: DynamicModule;
    static getModule(): DynamicModule {
        if (!this.instance) throw new Error(`XXXModule not initialized. Call XXXModule.forRoot(config) first.`);
        return this.instance;
    }
    static forRoot(): DynamicModule {
        if (!this.instance) {
            this.instance = {
                module: XXXModule,
                imports: [....],
                providers: [...],
                exports: [...],
            };
        }
        return this.instance;
    }
}

and for the import:

@Module({
    imports: [
        forwardRef(() => XXXModule.getModule()),
    ],
})

[johnnyomair]

You could move it to providers here: https://github.com/vivid-planet/comet/blob/feature/tenants/demo-saas/api/src/auth/auth.module.ts#L12. Then it should also be used for the dynamic module. Could you try that?

[raphaelblum]

@johnnyomair would you call this table

• UserToTenant?
• TenantToUser?
  or is TenantUser fine?

it's only an assignment table (for projects there might be a role as well here)

[johnnyomair]

I'd go with TenantToUser or UserToTenant. At least that's what we did for ProductToTag here:

comet/demo/api/src/products/entities/product-to-tag.entity.ts

Line 10 in 47944a7

export class ProductToTag extends BaseEntity {

[johnnyomair]

Naming: assignTenantUsersMutation.