HEALTH_CHECK_INTERVAL_MS was 1 h, but ROTATION_GRACE_PERIOD_MS is 15 min.
Phase skew between two peers' health-check ticks could stretch rotation
finalization desync up to ~1 h, during which signatures from the already-
finalized side verify against the other side's primary-only secret (grace
has expired; verifyPeerSignature stops trying the pending secret). With
AUTH_FAILURE_THRESHOLD = 5 and the existing backoff schedule, this
occasionally tripped legitimate rotations into needs_attention.
Setting the interval to 15 min (= ROTATION_GRACE_PERIOD_MS) guarantees a
finalization tick fires within one grace window on each side, so the
cross-verification window where one peer signs with NEW while the other
still treats NEW as pending cannot outlast the grace period.
Per-tick cost is negligible for the worker's steady state: the only
network fetches are per-active-peer /peer/rotate calls when the 90-day
rotation interval hits (rare) and per-unreachable-peer /instance/info
health pings (bounded by outage count). Going lower than 15 min would
reduce the residual desync but increase tick overhead with diminishing
returns; 15 min is the grace-period-aligned value that the original spec
("runs hourly") deviated from without justification.
Follow-up #20 from S2S DM unification backlog; reduces #19 false-positive
rate (outbox auth-failure transition) on legitimate rotations.
Add federation.md section 8b covering dm_close/dm_reopen relay events:
payload, outbound queueing via queueDmCloseRelay, inbound processDmCloseEvent/
processDmReopenEvent handlers (lookup-only identity resolution, silent
no-ops on missing channel/user/membership), and the processCreateEvent
closed-state reopen bug fix.
Update dm-system.md soft-close section with federation behaviour: relay
to peers for both close and reopen, relayed-message reopen in
processCreateEvent, and the federatedId-only guard for legacy DMs.
The client-side federation model (instanceStore, federated accounts,
multi-instance connections, origin-aware routing) was completely
undocumented. An agent reading only federation.md would understand S2S
relay but have no knowledge of how the client connects to multiple
instances, creates federated accounts with real credentials, or routes
API/WS calls to the correct instance.
New spec covers: instanceStore architecture, federated account creation
(username@instance format), Connections UI, auto-connect lifecycle,
channelOriginMap routing, WebSocket multiplexing, cross-instance
identity resolution, and the relationship between client-side and S2S
federation.
CLAUDE.md subsystem table updated. Both federation docs cross-reference
each other.
- Spec: status → Implemented, fix PATCH peer as new (not pre-existing),
correct API paths, update component breakdown to match actual structure
- Federation docs: update relay rate limit from 30 to 90 req/min
Prevent malicious peers from forging events attributed to users on other
instances. Every relay event processor now verifies the acting user's
homeInstance (from payload) matches X-Federation-Origin (from HMAC-verified
header) via verifyAttribution(), normalized to bare domain.
- Add verifyAttribution() helper using extractDomain normalization
- Guard all 13 event processors before any user resolution or DB writes
- Add homeInstance to FederationRelayReaction type + outbound payloads
- Replace unnormalized string equality in friend handlers
- Log mismatched values on rejection for debugging
Sliding-window rate limiter (30 req/min per peer origin) on POST
/api/federation/relay, matching the existing accept endpoint pattern.
Returns 429 when exceeded — outbox workers retry with backoff. Check
runs before HMAC verification to avoid wasted computation on floods.
Extract processRelayEvents() from the relay HTTP handler and call it
directly in runInitialSyncForNewPeers(), eliminating the HTTP round-trip
through public DNS that failed on networks without hairpin NAT.
Jannis Braun