ADR-0222: A view is listed only where its system has what it shows

• Status: accepted
• Date: 2026-11-01
• Deciders: Mahdi Amirabdollahi

Context

Rahdar runs more than one broker system. Several views and row actions were written for Artemis and listed for every cluster: the topology (management and Core URLs, HA pairs), routes, request-reply tracing, dead letters, the SQL console, flow, transfers, and a Connections page. On a Kafka cluster, which is reached by bootstrap servers and has no management URL, each of them showed Artemis words ("Management URL: None set", "Not polled: no management URL"), an empty page, or a link to a page that answers not-found. An operator reads a missing or empty page as a product that cannot do the job, and a page that cannot work as a lie.

Decision

• A navigation entry names the system it is for (system), as before, or the resource class it lists (resourceClass). The rail, the command palette and the g shortcuts list it only on a cluster whose system is that one, or whose kinds include a kind of that class. Until the cluster has said what it has, such an entry is not claimed.
• A slot contribution may name a system too, in any cluster-scoped slot. Row actions, selection bars and metric panels for one system are not offered on another (useClusterSlot).
• A route for one system answers not-found on a cluster of another (SystemGate), as the API does.
• A cluster's own address opens the first view its system offers, so an Artemis cluster lands on its topology and a Kafka cluster on its brokers.
• A capability the system lacks and the operator could add stays in the view that needs it, disabled with its reason (ADR-0216). This decision is only about views that mean nothing for the system.

Consequences

• A new system adds no entries to the views of another, and a new Artemis-only view must say so.
• The topology and the transfers are now Artemis-only. A Kafka cluster's brokers are on its Brokers view.
• A view that applies to every system but has nothing to show on one keeps its empty state; it is not hidden.

Alternatives considered

• Hide by a per-view capability probe: it needs a round trip per view and cannot tell "this system has no such thing" from "this cluster is down".
• Make the Artemis views system-aware: the topology would need a second vocabulary for Kafka that the Brokers view already provides.