The summary.
IN AN UNFAMILIAR CODEBASE, START WITH THE ROUTING DEFINITIONS
They are the map of what the application does. Then follow one request end to end.
Follow existing conventions even where you would have chosen differently — consistency matters more than preference, and unusual code frequently has a reason nobody wrote down.
IN REVIEW, RAISE SECURITY AND DATA ISSUES FIRST
They are the expensive ones. Automate formatting and linting so review addresses what only a person can judge.
DOCUMENT DECISIONS AND THEIR REASONING
The reasoning is otherwise lost, and the decision is reversed by someone who does not know the constraint.
Have someone new follow your setup instructions — they are the only person who can see what is unclear.
AGREE THE API CONTRACT BEFORE BUILDING
Both sides can then work in parallel. Never change a response shape without notice.
REQUEST IDENTIFIERS ARE THE DIFFERENCE BETWEEN DIAGNOSIS AND GUESSING
Reproduce outside production where you can, and add monitoring that would have caught it sooner.
ANYTHING DEPENDING ON A SYSTEM YOU DO NOT CONTROL TAKES LONGEST
Investigate the integration before estimating work that depends on it.
CHECK WHAT YOUR HOSTING SUPPORTS BEFORE CHOOSING A STACK
It eliminates options before you invest in evaluating them.
