Closes the 'live duplicate/conflict alerting also remains' gap noted
in §8.10: a durable domain.ErrConflict/ErrResultConflict rejection on
/v1/servers/{id}/{register,connect,disconnect,shutdown,result} was
already logged as a structured 'conflict' stage event, but had no
Prometheus signal distinct from the generic 4xx-class counter, which
also catches ordinary client noise (malformed bodies, expired
tokens). A real duplicate registration, raced reconnect, or replayed
result would have been invisible to alerting until someone went
looking through logs.
observability.Metrics gains ObserveServerConflict(kind), a bounded
counter keyed to serverMutation's own five routes (an unrecognized
kind folds into "other", so a caller mistake can't grow the label
set), exported as cosmic_clash_api_server_conflicts_total. Wired at
each of serverMutation's four conflict branches in server/api/service.go.
deploy/observability/prometheus-rules.yaml adds
CosmicClashControlPlaneServerConflicts, mirroring the existing
allocator quota-denial alert shape, firing on >3 conflicts of one
kind in 15 minutes.
Verified: go build/vet/test -race clean across every server package;
new unit tests cover per-kind counting, the bounded 'other' fallback,
the counter's absence until first observed, and a nil-receiver no-op;
a service-level test proves a real register conflict is exported
through the live /metrics endpoint. scripts/verify_observability_manifests.py
passes against the edited rules file.
Remaining, and explicitly out of scope here: this alert has only been
validated statically, never against a live Prometheus/Alertmanager
firing on real traffic — that requires the same live cluster this
sandbox has never had.
Josh Creek