Documents the top-level hub/ package shipped in PR #109 + revised in PR #122 (deadlock fix).

Covers public API surface, lifecycle ordering (HTTP listener bound during NewHub for immediate HTTPAddr availability, then NATS server ReadyForConnections), the SQLite tuning decision (busy_timeout yes, MaxOpenConns(1) explicitly no — see #120), the in-root vs. separate- module choice (with #118 as the migration path), and integration with the leaf agent (sim/hub_leaf_test.go::TestHubLeafE2E locks the contract).

Cross-referenced from agent-deployment.md and listed at the top of CLAUDE.md alongside the other ADRs.

Closes #114 check-in: afa1002be5 user: [email protected] tags: trunk