diff --git a/CHANGELOG.md b/CHANGELOG.md
index 06f7141..1114b8c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,30 @@ 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.
 
+## 2026-09-08 — "Last active" told you someone had been seen, not that they had said anything `api 0.108.0` `web 0.131.0`
+
+The per-user table on the Statistics page counted what each account had written, and showed when that
+account was last active. Those two are further apart than they look. Being active is bumped by any use
+of the product at all, so an account opened every morning to read reports that it was here today —
+and says nothing about whether the person has typed since March. On a screen whose job is to show who
+is actually using the instance, that gap is usually the thing being looked for.
+
+**A "Last message" column**, sitting next to the message count it belongs to: when each account last
+wrote, or "Never" if it never has. On a narrow screen it becomes its own labelled line on the card,
+rather than a second bare "3 days ago" beside the first one, which would have named neither.
+
+**This one column does not sort**, and the reason is worth stating rather than hiding. Every other
+column there is ordered by the database while it selects the page; this one is worked out afterwards,
+for the fifty accounts that page already chose. That is what keeps it from costing anything on a large
+instance, and it is also what leaves the server nothing to order by. "Last active" beside it still
+sorts, and answers the same question more coarsely.
+
+**Self-hosters:** one index on the messages table is replaced by a wider one leading on the same
+column — the old one is dropped and the new one built in its place, automatically when the api starts,
+like every schema change here. No column is dropped and nothing becomes unique, so the schema guard
+has nothing to refuse. On an instance with millions of messages the build is not instantaneous, and
+the api finishes starting when the index finishes.
+
 ## 2026-09-08 — Nobody running Jarvis could tell how much it was actually being used `api 0.107.0` `web 0.130.0`
 
 A platform administrator had no way to answer "is this instance quiet or busy, growing or stalled,