What does technical leadership involve for a senior engineer?

Seniority is measured by impact and judgement, not only by code volume.

Responsibilities

• Technical direction — define architecture, write ADRs and RFCs, and reduce risk before it becomes an incident
• Trade-off decisions — build vs buy, speed vs quality, consistency vs availability — explained in business terms
• Estimation and planning — give ranges, expose assumptions, slice work and communicate risk early
• Mentoring and review culture — raise the whole team's bar through constructive reviews, pairing and documentation
• Stakeholder communication — translate between engineering, product and executives; say no with alternatives
• Quality ownership — tests, observability, security and operability are part of "done"
• Delivery leadership — unblock others, manage dependencies and own outcomes, including mistakes

Habits: write things down, disagree and commit, measure results, and keep learning.