Why should system, database, and API documentation be stored in the repository?

Why should system, database, and API documentation be stored in the repository?

Keeping technical documentation in the repository makes the intended design available where implementation happens. Developers and coding assistants can inspect it alongside the current source instead of relying on an old chat or a document whose version is unclear.

Version decisions together with code

A database change often affects more than a model file. Adding an event timezone may require API validation, form updates, and clarification about how scheduled times are displayed. Updating the related documentation in the same change makes that relationship visible.

Version history also preserves the reasons behind decisions. A short architecture note can explain why the first release uses one application service or why invitation responses have a separate access path.

Create a reliable starting point

A new coding session can read a concise documentation index before editing. Useful files might include a system overview, entity relationships, endpoint contracts, and development instructions. Clear paths allow prompts to reference exact sections rather than restating the entire project.

For a wedding-management feature, the assistant should be able to discover which entity owns an event, how organizer access is checked, and what the event-creation endpoint returns.

Prevent documentation from drifting

Repository storage does not automatically keep documents accurate. Treat changes to interfaces and business rules as prompts to update their references. During review, compare documentation examples with the implementation and remove obsolete alternatives.

Keep secrets and private production data outside these files. Environment examples should describe variable names and expected formats without including live values. Use fictional request and response examples.

Documentation works best when it is concise, findable, and maintained with the feature. Its purpose is to make the next implementation decision more dependable, not to create a large collection of pages nobody trusts.