Code is a detailed record of a result. It can show which branch runs, how data moves, and what happens when an input is invalid. It often cannot explain why this result was preferred over another reasonable design.
That missing reason matters later.
A future reader may see a strange-looking constraint and “clean it up.” The change may be locally elegant and still restore a problem that the original design prevented. Without context, the reader must guess whether the shape is deliberate, accidental, or simply old.
I use short decision records to reduce that guessing.
What deserves a record
Not every coding choice needs a document. Naming a local variable or choosing a familiar loop usually does not carry enough long-term consequence.
A decision becomes worth recording when it changes a boundary, accepts an important trade-off, limits future options, protects a security or privacy rule, or rejects an alternative that another engineer is likely to suggest again.
The test is simple: if a careful person may later ask “Why did we do it this way?”, a short answer should be easy to find.
The decision is more than the result
A useful record includes five parts:
- The situation that created the decision.
- The constraints that mattered.
- The options that were seriously considered.
- The chosen direction and its reason.
- The consequences, including the cost we accepted.
The fifth part is important. A record that only praises the chosen option is not honest enough. Every meaningful decision gives something up: simplicity, flexibility, speed, reach, or control.
Naming that cost helps a future reader know when the decision should be reviewed.
Write for the next decision
A decision record should not try to become a full history of the project. It should give the next person enough context to make the next related choice.
This usually means short, direct language. I prefer concrete statements such as “The public site must remain static” over broad claims such as “This architecture is more scalable.” The concrete statement can be tested. The broad claim invites arguments about an undefined future.
Dates and status also matter. A decision can be accepted, replaced, or no longer relevant. Keeping old records is useful when their status is clear because they show how the system reached its current shape.
Put the record near the work
Documentation becomes weak when it lives far from the thing it explains. A decision about repository architecture should live in the repository, use the same review process, and change through the same history.
This does not guarantee that the record stays correct. It makes correction easier. A pull request that changes the architecture can update the decision in the same review.
The alternative is often a document platform that few people remember to check. The writing may be polished, but its distance from the code turns it into a separate memory.
Comments still have a role
A decision record does not replace comments. They answer different questions.
A comment can explain a narrow local fact: why an unusual check is needed or why an API must be called in a specific order. A decision record explains the wider choice: why the system uses that API or why the boundary exists at all.
The closer the explanation is to a line of code, the more likely it belongs in a comment. The more it affects several files or future directions, the more useful a decision record becomes.
Avoid writing theatre
Documentation can become a performance. A team may create a long template, fill it with formal language, and still leave the real trade-off unclear.
The goal is not to prove that a process happened. The goal is to preserve useful reasoning.
I would rather read six honest paragraphs than six pages of repeated headings. A small record is easier to review and more likely to be updated when the decision changes.
The value appears later
The benefit of a decision record is rarely visible on the day it is written. It appears months later, when someone can understand a constraint without repeating an old investigation.
It also appears during disagreement. The record moves the conversation away from memory and toward the actual assumptions behind the choice. If those assumptions no longer hold, the system may be ready to change. If they still hold, the unusual shape may still be doing useful work.
Code tells us what survived. A decision record tells us what was considered. Keeping both gives future work a stronger starting point.