Ideas

The Scion pattern

One authoritative history, every change a small logged changeset, and summaries derived from the log.

Where it comes from

This pattern comes from a published write-up on server-side source control called Scion. In it, history and blame are things you can ask for, not just files you dig through.

The parts

• One authoritative history. One place holds the real history.
• Small logged changesets. Each change is one logical unit, with who made it and why.
• Derived summaries. Indexes, logs and reports are computed from the history. Nobody writes them by hand.
• A dedicated follower. Someone, or something, follows each part and reports on its changes.

Asking "who changed this, and why?"

Because every change carries its reason, you can point at any line and ask who changed it and why.

Why it matters

When many people or agents change things, the hard question is not what changed. It is who decided. This pattern keeps that answer one question away.

Conventions and the Wiki follow this idea.