Branch-by-abstraction for the control-plane store (issue 0003b), so the
membership state can move off process-local SQLite onto replicated
JetStream KV without rewriting callers and without breaking master.
pkg/membership:
- Store is now an interface (rooms/members/keys + user allowlist +
Close). The existing SQLite implementation is renamed sqliteStore and
stays the default: Open(path) still returns it. openSQLite keeps the
concrete type for internal callers (the 0003c migration).
- ErrNotFound is a storage-agnostic "no such record" sentinel; both
backends return it (the SQLite store maps sql.ErrNoRows to it). The
control plane now branches on ErrNotFound instead of sql.ErrNoRows, so
server.go no longer imports database/sql.
- jetstreamStore (new) implements Store over five replicated KV buckets:
rooms, members, rooms_by_member (reverse index for ListRoomsForEndpoint),
room_keys, users. Replication factor is configurable (R1..R5) for the
R1->R3 rollout. Every read is bounded by OpTimeout and IsAuthorized /
HasAdmin FAIL CLOSED on any backend error (a KV quorum loss denies,
never admits), per the audit's requirement for the decentralized store.
dev/feature_flags.json:
- Add the `decentralized` flag (OFF): sqliteStore default while off,
jetstreamStore behind it. The membershipd boot wiring that selects the
KV store is deliberately deferred to 0003e/0003f (the embedded-NATS
authenticator<->store bootstrap is part of the session/deploy redesign);
OFF keeps the single-node SQLite control plane unchanged.
Tests (DoD: golden + edges + error path):
- TestJetStreamStoreRoomsCRUD: encrypted room + owner + invited member
round-trip through every room/member/key method, including latest-epoch
resolution and rekey.
- TestJetStreamStoreUsers: add/get/authorize/list/revoke + admin gate,
with case-insensitive key normalization and duplicate rejection.
- TestJetStreamStoreNotFound: ErrNotFound mapping for misses.
- TestJetStreamStoreIsAuthorizedFailClosed: NATS backend shut down ->
IsAuthorized and HasAdmin both DENY within the bounded timeout.
The full existing suite stays green: sqliteStore is unchanged behavior.
A peer invited to an encrypted room needs to find it: the control plane is
pull-based (no server push of invitations), so add a discovery endpoint that
lists every room an endpoint belongs to, with the room's metadata and the
endpoint's role.
- store.ListRoomsForEndpoint: JOIN members+rooms, ordered by room id, empty
slice (not error) for an endpoint in no rooms.
- membershipd: GET /members/{endpoint}/rooms returns {room_id, subject, epoch,
policy, role}[].
- client.ListMyRooms + RoomRef: a bot polls this to discover and then Join +
Subscribe rooms it was invited to.
Tests: store-level (owner in N rooms, member in one, unknown endpoint → []) and
client-level e2e through the embedded harness (B discovers a room A invited it
to, without prior knowledge of the room id; owner sees role=owner).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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