Architecture decision records

Goal

Preserve the reasoning behind architecturally significant decisions so that later contributors can tell a deliberate choice from an accident and know what would have to be true to revisit it.

Prerequisites

A directory in the repository (for example docs/adr/) and agreement that decisions with lasting consequences get a record.

Steps

1. Number records sequentially and give each a short title: 0007-use-postgresql-full-text-search.md.
2. Use Nygard's sections: Context (forces at play, in neutral language), Decision (stated in full sentences, active voice), Status (proposed, accepted, deprecated, superseded by …), Consequences (what becomes easier and what becomes harder).
3. Write the record when the decision is made, not months later; keep it to one or two pages.
4. Never edit an accepted record's decision; write a new record that supersedes it and link both ways.
5. Review records in the same pull request as the change that implements them.

Expected result

A newcomer can read the records in order and reconstruct why the system looks the way it does. Reversals are visible as new records rather than silent rewrites.

Limits and test basis

Records document decisions, not designs; diagrams and specifications live elsewhere. Too many trivial records bury the important ones, so agree on a threshold of significance. The format follows the cited sources; the value depends on discipline, not tooling.