Sync the self-hosting stack

CHANGELOG.md

@@ -9,6 +9,37 @@ one of them changed. An entry says which artefact and which version, so `web 0.1
 Every version published to a channel appears here. Nothing is written from memory afterwards: a build
 cannot be published without its entry.
 
+## 2026-08-28 — A machine that moves between replicas lets go of the old one `api 0.98.0`
+
+**Only affects deployments running more than one copy of the api.** Nothing here changes a single-
+container stack.
+
+**Reconnections are tidied up immediately instead of being waited out.** When a machine reconnects
+to a different replica, the one it left still held its old connection until its own liveness check
+noticed — up to thirty seconds in which two replicas each believed they could talk to the same
+machine, and a command could be sent down the connection the machine had already abandoned. The
+replica that takes over now tells the other one to let go, straight away and precisely: only the
+connection that was actually replaced is closed.
+
+**And you can now see what the presence machinery is doing**, at
+`GET /api/admin/agents/presence`, for platform administrators. It reports five counters, added up
+across every replica rather than only the one that answered your request:
+
+- how often a machine's connection moved from one replica to another;
+- how often a closing connection was found to have already been replaced, and correctly ignored;
+- how often a command followed a machine that moved instead of failing;
+- **how often a command could not be delivered at all** — this is the one worth alerting on, because
+  it is what someone experiences as "the agent is not connected";
+- how often a stored status had to be corrected because it said a live machine was offline. This
+  should sit at zero; if it does not, please tell us.
+
+It is JSON, every counter only ever goes up, and a replica that has stopped reporting is excluded
+from the totals and counted separately — so you can point a scraper at it with a service account.
+There is deliberately no unauthenticated `/metrics` endpoint: your replica count and machine totals
+are facts about your estate, not about Jarvis.
+
+**Nothing to do.** Take the build.
+
 ## 2026-08-28 — Machines no longer flicker offline when they reconnect `api 0.97.0`
 
 **Only affects deployments running more than one copy of the api.** On Docker Compose one of these