fix(dashboard): ShowTagValues now gates the alarms hub and /browse live values

docs/GatewayDashboardDesign.md

@@ -273,7 +273,7 @@ bearer). Each hub class is `[Authorize(Policy = HubClientsPolicy)]`.
 | Hub | Path | Producer | Payload | Routing |
 |---|---|---|---|---|
 | `DashboardSnapshotHub` | `/hubs/snapshot` | `DashboardSnapshotPublisher` (BackgroundService consuming `IDashboardSnapshotService.WatchSnapshotsAsync`) | `DashboardSnapshot` | Sent to all connected clients on every snapshot tick, but only while at least one client is connected (see "Idle gating" below); new connections receive the current snapshot synchronously in `OnConnectedAsync`. |
-| `AlarmsHub` | `/hubs/alarms` | `AlarmsHubPublisher` (BackgroundService consuming `IGatewayAlarmService.StreamAsync(filter: null)`) | `AlarmFeedMessage` (`active_alarm` / `snapshot_complete` / `transition`) | Connected clients auto-join `__alarms__`; all clients receive every message. Publisher auto-reconnects every 5s on stream faults. |
+| `AlarmsHub` | `/hubs/alarms` | `AlarmsHubPublisher` (BackgroundService consuming `IGatewayAlarmService.StreamAsync(filter: null)`) | `AlarmFeedMessage` (`active_alarm` / `snapshot_complete` / `transition`) | Connected clients auto-join `__alarms__`; all clients receive every message. Publisher auto-reconnects every 5s on stream faults. The alarm value fields (`current_value` / `limit_value`) are stripped from a deep-cloned copy of the message when `Dashboard:ShowTagValues` is false (the default) — on both value-bearing payload arms, so neither a live transition nor a snapshot record leaks a process value; every other field still renders. The source message is never mutated: it fans out from the same feed to gRPC `StreamAlarms` subscribers, which this dashboard-display flag does not govern. Arms carrying no value are forwarded as-is, uncloned. |
 | `EventsHub` | `/hubs/events` | `DashboardEventBroadcaster` invoked by each session's internal dashboard-mirror subscriber on its `SessionEventDistributor` (registered when the session becomes Ready) | `MxEvent` | Clients call `SubscribeSession(sessionId)` to join `session:{id}`, which also registers them in `EventsHubViewerRegistry` — the mirror is gated on that registry, which counts hub and in-process viewers alike (see "Mirror gating" below). The dashboard is a first-class distributor subscriber, so it receives the session's events whether or not a gRPC client is streaming. It sees RAW session events — not the per-gRPC-subscriber `AfterWorkerSequence` filtering that `EventStreamService` applies at its own boundary — because the dashboard is a separate LDAP-authenticated monitoring view meant to show the session's full event activity. Tag values are stripped from the mirrored `MxEvent` copy by `DashboardEventBroadcaster` when `Dashboard:ShowTagValues` is false (the default) — event metadata (tag reference, quality, status, timestamps) still renders, but the value fields are blanked, so no value leaks through this seam. `SubscribeSession` is gated by `IDashboardSessionAcl` (SEC-25 / TST-15): a denied caller gets a `HubException`, is not joined to the group, and is not registered as a viewer, so the mirror stays off for a session nobody is legitimately watching. The same ACL gates the in-process seam the session-details page uses, so neither path is the weaker one. Value redaction remains an independent layer — it bounds what a *permitted* subscriber sees. |
 
 ### Default cadences
@@ -517,12 +517,15 @@ tree to a flat list of matching attributes.
 
 Right-clicking an attribute (or double-clicking it) adds it to the subscription
 panel. The panel shows each subscribed tag's live value, MXAccess data type,
-quality and source timestamp, refreshed every two seconds. The subscription
-panel is the explicit opt-in tag-value surface: it always shows values
-regardless of `Dashboard:ShowTagValues`, which governs the diagnostic
-session/worker views and the per-session event mirror — both its hub and
-in-process audiences (values are redacted from the mirrored events when the flag
-is false).
+quality and source timestamp, refreshed every two seconds — but the value column
+obeys `Dashboard:ShowTagValues` like every other dashboard value surface. With
+the flag false (the default) `DashboardLiveDataService` hands the page
+`[redacted]` in place of the formatted value; data type, quality, source
+timestamp and any read error are untouched, so the panel still answers "is this
+tag advising and healthy" without disclosing the value. The substitution happens
+at the service, not in the page: one decision point, and the value never enters
+the render tree. Set the flag true to make the panel the explicit opt-in
+tag-value surface it was originally designed as.
 
 ### Alarms page