SAGE Router adds a SELF/COLLABORATE/HANDOFF decision layer above A2A discovery.

The argument is that agent discovery answers which agents exist but not who should work with whom once execution has begun. It evaluates three routes in one auditable objective: SELF when existing capability and context suffice, COLLABORATE when a small complementary team covers missing requirements, and HANDOFF when specialist advantage exceeds context-transfer loss. MIT, Python 3.10+, research preview, 677 stars in two days. (GitHub) "Specialist advantage exceeds context-transfer loss" is the right way to frame the handoff decision and I haven't seen it stated that cleanly before.