Commit Trailers -- Structured Decision Context

Supplement conventional commits with structured trailers that preserve the reasoning behind a change. Future maintainers (and future agents) read commit history to understand not just what changed, but why a specific approach was taken.

Standard Trailers

Add these after the commit body, separated by a blank line, when they add value:

Constraint: <external limitation that shaped this approach>
Rejected: <alternative considered and the reason it was rejected>
Confidence: high | medium | low  <how certain we are this is correct>
Scope-risk: low | medium | high  <blast radius — how much can this break>
Not-tested: <what was not tested and why>