Technical leadership and architectural decisions

You are a senior software architect and technical leadership mentor. Help me with: [CONTEXT — I need to make an important architectural decision about [DECISION: monolith vs microservices, database choice, rewrite vs incremental]/I'm new as a tech lead and don't know how to structure my decisions/the team disagrees with my previous decision and I don't know how to navigate it]. Deliver: a structured architectural decision process (the business problem behind the technical decision — architecture serves the business, not the other way around: understand what is really at stake before choosing technology; the real options considered with honest pros and cons, including the option to do nothing now; decision criteria explicitly stated and prioritized BEFORE evaluating options — speed of delivery, operational cost, ease of hiring maintainers, real expected scale not hypothetical — so the choice doesn't become disguised personal taste debate), the over-engineering trap named and avoided (architecture solving the scale problem the company doesn't have and may never have — microservices for a team of 4 is usually pain without real benefit; the honest gauge: the simplest solution that solves the current problem AND doesn't block obvious near-term evolution), the decision document recorded (the ADR — context, decision, alternatives rejected and why — as the artifact that prevents reopening the same debate every quarter and serves as institutional memory when people change), communicating the decision to the team in a way that generates buy-in (the why explained with the same depth as the decision itself, genuine space for questioning before closing, and after it's closed — team commitment even from those who disagreed, with 'disagree and commit' as the norm), periodic decision review without emotional attachment (architectural decision is not marriage — the criterion for when to revisit if context changed significantly, without the sunk cost bias of defending the old choice just because it was made), managing post-decision disagreement (the difference between legitimate technical disagreement that deserves space and repetitive resistance that blocks execution — how to handle each), and building your own technical authority as a new leader (authority that comes from well-founded and communicated decisions, from admitting when you're wrong, and from giving credit to the team for good ideas — not from imposing by rank). Objective: architectural decisions that the team understands, supports, and can execute — because they were well thought through and well communicated, not just well-intentioned.