Spec-driven development on OpenSpec, with mechanical spec-as-source enforcement: a custom 'spec-as-source' OpenSpec schema adds file-ownership (targets) and test-verification ([@test]) metadata to every capability spec, three scripts (link check, ownership check, manifest build) keep code and specs from drifting apart, plus requirement-gathering, spec-writer, work-review, and a session-handoff skill with a proactive context-warning hook.