## Describe your changes
A group could be deleted while a reverse proxy service still referenced
it, silently breaking the service's access control: private services
list groups in `access_groups` as the peer allowlist, and SSO bearer
auth distributes tokens to `distribution_groups`.
Group deletion now runs through the same linkage validation as routes,
policies, and agent network policies: deleting a group that backs a
private service allowlist or an enabled bearer-auth distribution list
fails with a `GroupLinkError` naming the service domain. Disabled bearer
configs and stale `access_groups` on non-private services are inert and
do not block deletion.
Tests cover both linked cases in single and bulk deletion, and pin the
non-blocking cases. The test account seeds decoy services ahead of the
linked ones so the check is proven to scan the full service list.
Block deleting a group referenced as a source group by an agent network
policy, and drop unresolvable groups from synthesised private-service
ACLs. A deleted group survived in agent_network_policies.source_groups
and was carried into the injected in-memory policy, where network-map
assembly resolved it to a nil group and panicked on every proxy peer
sync.
## Describe your changes
Work on the Terraform provider (terraform-provider-netbird #177–#183)
surfaced places where the agent-network API broke its own contracts or
deviated from the conventions the rest of the management API follows,
forcing client-side workarounds.
Settings reads now follow the settings-endpoint convention: GET always
answers with a JSON object. Before bootstrap it returns the defaults
with an empty cluster/subdomain/endpoint (previously 200 with a JSON
`null` body, while the spec said 404). The settings PUT can bootstrap
the account by carrying a `cluster` — previously the row could only come
into existence through the first provider create, and a settings-first
setup was impossible; a differing cluster on a bootstrapped account is
rejected instead of silently ignored. PUT remains full-state.
The provider PUT schema promised omit-preserves semantics for several
operator-editable fields that the handler never delivered (it builds the
row from the request, like every other update handler). The schema
wording now matches the shipped full-state behavior; only the api_key
(secret) and session keys stay preserved by the manager. Identity
headers are always present in provider responses so an explicitly
cleared value round-trips as an empty string.
The Go REST client gains the full agent-network surface (catalog,
providers, policies, guardrails, budget rules, settings), including a
shim translating the legacy 200+`null` settings body from older servers
into an `IsNotFound` error.
Note for reviewers: the dashboard special-cased the `null` settings
body; it needs a small follow-up for the new defaults response (in
progress).
