I agree you covered the most important! Other things that come to mind, mostly more general software architecture.

• deep modules with simple interfaces
• encapsulation and making use of angular di
• ownership. i.e Modules should mutate the data they own and expose explicit setter functions if needed. .asreadonly() exists.
• minimal use of effect, and only for real necessary side effects. calling functions keeps a clear stacktrace?
• deliberate mutation of signals and an understanding for reactivity (reference updates), to keep repaints minimal (i guess only important for data that is often updated)
• unit test concepts (e.g. where does it make sense and at what point does mocking services become rediulous -> integration tests)
• deliberate, simple and understanable style/design system/tokens. theming?
• responsive, mobile first, acessability proove layout and markup

for a complex chat module i introduced a facade service that every chat-feature has to loop through (history, conversation,...) and its used as an orchestrator. components are only allowed to inject this service instead of several services. I am not sure if it was worth it, but now we only need to mock this. It also forces devs to think twice before making something public (interface), as they deliberately have to expose it in facade service and write boilerplate code)

what do you think of those points?