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

docs/GatewayConfiguration.md

@@ -192,7 +192,7 @@ events (a "gap") and must re-snapshot; whatever is still retained is replayed.
 | `MxGateway:Dashboard:SnapshotIntervalMilliseconds` | `1000` | Dashboard snapshot refresh interval used by the snapshot SignalR hub and the pages that subscribe to it. |
 | `MxGateway:Dashboard:RecentFaultLimit` | `100` | Maximum number of fault summaries projected into each dashboard snapshot. |
 | `MxGateway:Dashboard:RecentSessionLimit` | `200` | Maximum number of session summaries projected into each dashboard snapshot. |
-| `MxGateway:Dashboard:ShowTagValues` | `false` | Controls whether tag values reach the dashboard's SignalR events hub mirror. `false` (default): `DashboardEventBroadcaster` blanks tag values from a deep-cloned copy of each `MxEvent` before it reaches any hub subscriber — event metadata (tag reference, quality, status, timestamps) still renders; see `docs/GatewayDashboardDesign.md`'s `EventsHub` row for the mechanism. This is now the second of two independent layers, not the only one: `IDashboardSessionAcl` decides *which* sessions a caller may subscribe to at all (see `GroupToTag` / `UntaggedSessionVisibility` below), while this flag decides what a permitted subscriber sees. Setting it `true` therefore exposes tag values to everyone the ACL admits — every Administrator, plus each Viewer holding a matching tag. The flag gates only the SignalR events hub mirror — it does **not** cover the `/browse` live-value display, nor the alarms hub (`AlarmsHubPublisher` broadcasts alarm transitions with their `current_value`/`limit_value` fields unredacted); both remain separate, still-open residuals. |
+| `MxGateway:Dashboard:ShowTagValues` | `false` | Controls whether tag values reach the dashboard at all. `false` (the default) suppresses them on all three seams that carry one: (1) the **events hub mirror** — `DashboardEventBroadcaster` blanks `MxEvent.value` plus the alarm body's `current_value`/`limit_value` from a deep-cloned copy before it reaches any hub subscriber (see `docs/GatewayDashboardDesign.md`'s `EventsHub` row); (2) the **alarms hub** — `AlarmsHubPublisher` clears `current_value`/`limit_value` from a deep-cloned copy of each `AlarmFeedMessage`, on both value-bearing payload arms (`transition` and `active_alarm`), before broadcasting to `/hubs/alarms`; (3) the **`/browse` live-value panel** — `DashboardLiveDataService` substitutes the literal `[redacted]` for each tag's value text. Both hub redactions clone: the source `MxEvent` is shared with the gRPC event stream and the replay ring, and the source `AlarmFeedMessage` fans out to gRPC `StreamAlarms` subscribers, so neither is mutated in place and **no gRPC client is affected by this flag** — it is a dashboard-display control only. Everything that is not the value survives on every seam: tag reference, alarm reference/severity/state/operator, data type, quality, status, and timestamps still render, so the dashboard stays diagnostic without disclosing process values. This is one of two independent layers: `IDashboardSessionAcl` decides *which* sessions a caller may subscribe to at all (see `GroupToTag` / `UntaggedSessionVisibility` below), while this flag decides what a permitted subscriber sees. Setting it `true` exposes tag values to everyone the ACL admits — every Administrator, plus each Viewer holding a matching tag — and, because the alarms hub is session-less, exposes alarm values to every dashboard client that can reach `/hubs/alarms`. |
 | `MxGateway:Dashboard:GroupToRole` | _(empty)_ | LDAP group → dashboard role mapping. Keys are LDAP group names (short CN or full DN — leading-RDN match). Values must be `Administrator` (read/write, API-key CRUD) or `Viewer` (read-only) — matched ordinally by the startup validator, so the spelling is exact and `Admin` is rejected. A user whose LDAP groups don't intersect this map cannot sign in; with no mapping at all, only the loopback bypass admits anyone. |
 | `MxGateway:Dashboard:GroupToTag` | _(empty)_ | LDAP group → dashboard visibility tags. Keys follow the same convention as `GroupToRole` (short CN or full DN — leading-RDN match, case-insensitive); values are tag lists. A dashboard user's granted tag set is the union over the groups they belong to; an unmapped group contributes nothing. **Visibility only:** tags scope which sessions' event streams a Viewer may observe on the dashboard — they never grant or deny data access, which stays with the API key's scopes and constraints. Independent of `GroupToRole`: a group may appear in either map, both, or neither. Empty (the default) means Viewers hold no tags, so under the default `UntaggedSessionVisibility` they observe no session's events. |
 | `MxGateway:Dashboard:UntaggedSessionVisibility` | `AdminOnly` | Who may observe a session that carries no tags (its owning API key declared none). `AdminOnly` (default, fail-closed) restricts untagged sessions to dashboard Administrators. `AllViewers` shows them to every Viewer — opt-in for a single-tenant deployment that wants the pre-tag behaviour. Administrators always see every session regardless of tags. |

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