I've been in the role of Technical Architect for a few months now, and one thing has become clear, it isn't a clear cut role with a 'generic' job description. Each Architect has different expectations from the role. Some Architects want to remain very much part of the development team, fitting into projects for the entirety of the project. Others want to be very involved in the pre-build tasks and step away from the coding, and there is a variety of interpretations in between.
Above is what I would consider to be a 'good template' for how a project should run, but remember, it is a template. The scale and type of project will have a huge impact on this. A small team of developers vs. a large team of developers will create variations of the project. The key thing for me is not to have an architect on the project full time for the entire length of the project.
It isn't cost-effective for the client, it isn't a good use of the Architect's time. Once the project is self-sufficient and in full flow, an Architect should only get involved to help maintain high standards, ensure the developers are working efficiently, and finally putting out any fires (which will happen).
So, my role(s). What is it I do as a Technical Architect?
I currently am involved in helping to prepare pitches, being involved in pitches, running discovery workshops, documenting findings from the workshops, building out proof of concepts, reviewing steering wireframes, designs and functional specifications, writing technical specs, architecting/developing the initial solution (inc. design patterns, testing strategies, CI/CD, etc.).
As the project moves into full flight, stepping away from the development. Focussing overviewing code quality, reviewing pull requests, etc.
Finally, as the project completes, supporting the transition to at BAU/support team.
The only spanner that tends to be thrown in the works with this is the Project Managers. Who (obviously) want the most experienced developers working on their projects. They often still see Technical Architects as a developer resource and will fight to keep them developing full time on a project for its entire life cycle.