Decision write-ups

Short “why we chose X” pages, not the full explanation book. Start here when someone asks why the plane looks the way it does.

• Why opaque checkpoint proxy: plane stores bytes; frameworks own serde
• Why generation fencing: stale runners must not clobber reclaim winners
• Why fail-closed serve: ambiguous auth or policy → deny, don’t guess
• Why Agent Protocol on the front: clients stay framework-agnostic; reclaim stays internal

Longer primers: chapters. Mechanism deep-dives: engineering notes.