Three questions before you merge.
A small habit for examining assumptions, failure paths, and the code just outside the diff.
There is no universal checklist that can understand a codebase for you. A few focused questions can still help you decide where to spend your attention when reading a change.
What has to be true?
Look for the conditions the change relies on. A value must exist. A user must have permission. A caller must provide a particular shape of input. Find where those conditions are established.
If an assumption is only in someone's head, ask whether it can be made visible in the code. A type, a guard, or a focused test can give the next reader something concrete to rely on.
What happens when it fails?
Follow a failure through the code. Where is it detected? Who handles it? What does the user or caller see? The interesting detail is often the transition between two layers.
- An external request returns an error.
- A record disappears before an operation finishes.
- An optional value is absent.
- A retry repeats an operation that already partly succeeded.
Choose cases relevant to the actual change. The purpose is to make a specific behavior clearer, rather than attach every imaginable failure to every pull request.
Who else depends on this?
Trace the result to the next caller, the next screen, or the next write. A small local change may alter a contract elsewhere. Reading one step further can turn a vague concern into a concrete observation.
Before the merge, make the assumptions visible.
These questions are a starting point for a conversation. Share what you found, explain the connection, and let the author bring the context you may be missing.
Every line. Worth a second look.