Phase 1 — Transport layer fix:
- Bake in default MESH_PEER_PUSH_SECRET so peer push, real-time
propagation, and pull-sync all work out of the box instead of
silently no-oping on an empty secret.
- Pass secret through docker-compose.yml for container deployments.
Phase 2 — Per-gate content keys:
- Generate a cryptographically random 32-byte secret per gate on
creation (and backfill existing gates on startup).
- Upgrade HKDF envelope encryption to use per-gate secret as IKM
so knowing a gate name alone no longer decrypts messages.
- 3-tier decryption fallback (phase2 key → legacy name-only →
legacy node-local) preserves backward compatibility.
- Expose gate_secret via list_gates API for authorized members.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
