fix(dashboard): bounded alarm drains, feed resubscribe, live pill, drop dead hub factory; doc corrections

docs/GatewayDashboardDesign.md

@@ -118,8 +118,11 @@ so it consumes the producing services directly through in-process seams —
 `IDashboardSnapshotFeed`, `IDashboardSessionEventSubscriber`, and
 `IGatewayAlarmService` — instead of opening a loopback WebSocket back into its
 own heap. `DashboardHubConnectionFactory`, the helper a circuit used to open
-those connections, stays registered for out-of-tree consumers, but no in-repo
-page resolves it.
+those connections, has been deleted along with the `Microsoft.AspNetCore.SignalR.Client`
+package reference: nothing in this process dials a hub, and a registered-but-unused
+client factory only invites a page to reintroduce the loopback. Remote consumers
+build their own connection; the hubs, `/hubs/token`, and `HubTokenService` remain
+for them.
 
 ## Dashboard Data Source
 
@@ -195,7 +198,27 @@ instead of buffering without bound or stalling the pump.
 `DashboardPageBase` seeds `Snapshot` synchronously from
 `IDashboardSnapshotService.GetSnapshot()` in `OnInitializedAsync` so the first
 render is non-empty, then calls `InvokeAsync(StateHasChanged)` for every snapshot
-the feed yields. On dispose it cancels the watch and waits at most **5 seconds**
+the feed yields.
+
+A subscription is not a lifetime, so the watch is a loop, not a single enumeration:
+the feed detaches its subscribers whenever a pump's source faults or completes, and
+a page that treated that as terminal would sit on its last snapshot until the
+operator navigated. On any end other than its own cancellation the page waits one
+second — honouring its own token, so teardown is not delayed — and resubscribes. The
+fault is logged at Warning once per fault *transition*, not once per retry: a feed
+that is down stays down for many iterations, and one line per second per open page
+is noise. The last rendered snapshot stays on screen throughout, and the next page
+load still seeds from `IDashboardSnapshotService.GetSnapshot()`.
+
+That resubscribe is also the feed's primary recovery path, not just the page's:
+only a subscriber that finds no live generation starts a pump, so a page coming back
+is what restarts the enumeration. `Reset`'s belt-and-braces restart — if subscribers
+of *other* generations are still attached when a generation dies, it starts a fresh
+pump for them and re-tags them — remains the backstop for the case where no
+subscriber is left to drive recovery, but it is no longer the only thing standing
+between a faulted feed and a permanently stale page.
+
+On dispose the page cancels the watch and waits at most **5 seconds**
 for the loop to drain, logging a warning on timeout. The bound is deliberate: the
 loop marshals renders through the renderer's dispatcher and disposal can run on
 that same dispatcher, so an unconditional wait would hang on a wedged dispatcher.
@@ -214,6 +237,19 @@ Detaching cancels the pump, disposes the subscription (which releases the viewer
 registration and completes the channel, so the pump has an exit even if
 cancellation is missed), then drains under its own timeout.
 
+The page's live/offline pill tracks that pump rather than a connection: it is set
+live on attach and cleared when the pump exits, through the same dispatcher-owned
+identity check the render batch uses, so a stale pump cannot darken the pill of the
+subscription that replaced it. Because detach clears the subscription field before
+cancelling, a detach-driven exit leaves the pill to the incoming subscription; what
+the pill therefore reports is the case it exists for — the channel completing under
+a page that is still watching.
+
+`AlarmsPage` owns two loops of its own (the 3 s alarm poll and the provider-status
+badge) and bounds each drain at 5 seconds on dispose, for the same reason
+`DashboardPageBase` bounds its watch drain: both loops render through the renderer's
+dispatcher, and disposal can run on it.
+
 ### SignalR hubs (remote clients)
 
 Updates for out-of-process clients flow over three SignalR hubs, all guarded by the
@@ -329,9 +365,14 @@ ordering — register before becoming a delivery target, deregister after ceasin
 be one — so the widest a race window opens is a redaction clone that reaches
 nobody, never a dropped event that was owed to a live viewer.
 
-Redaction happens once per event, not once per audience: `Publish` produces a
-single redacted clone and hands that same instance to the in-process subscribers
-and to the hub group. In-process delivery runs first and synchronously — it cannot
+Redaction happens once per event, not once per audience: with
+`Dashboard:ShowTagValues` false (the default) `Publish` produces a single redacted
+clone and hands that same instance to the in-process subscribers and to the hub
+group. With `ShowTagValues` true there is no clone at all — the original `MxEvent`
+instance is handed to both audiences — so the "one clone per event" cost holds only
+in the redacting configuration, and in the value-showing one both audiences share a
+reference to the session pipeline's own event object. In-process delivery runs first
+and synchronously — it cannot
 throw, and it must not be skipped by the guard clause around the hub send — into
 per-subscriber bounded drop-oldest channels, so a page that falls behind loses its
 oldest queued events rather than blocking the session's event pipeline.
@@ -715,11 +756,10 @@ dashboard mints short-lived bearer tokens for the connection:
 5. The hubs' `[Authorize(Policy = HubClientsPolicy)]` accepts the resulting
    identity.
 
-`DashboardHubConnectionFactory` (scoped to the Blazor circuit) wraps the
-HubConnectionBuilder and supplies a fresh token via `AccessTokenProvider` on
-every (re)connect, so the short 5-minute lifetime is transparent to whoever uses
-it. It remains registered, but no in-repo page opens a hub connection any more;
-external clients implement the equivalent refresh themselves.
+There is no in-repo hub client: the helper that once wrapped `HubConnectionBuilder`
+for a circuit was deleted when the pages moved to the in-process seams. An external
+client re-fetches `/hubs/token` on every (re)connect itself, which is what makes the
+short 5-minute lifetime transparent.
 
 Caveat — logout does not revoke outstanding tokens. Logout clears the dashboard
 cookie, but hub bearer tokens are self-contained, data-protection-encrypted, and