Keep a person's last sign-in when their sessions go away

CHANGELOG.md

@@ -10,6 +10,15 @@ Newest first. `Unreleased` is what is on `main` and not yet tagged.
 
 ## 0.0.9
 
+### The People screen keeps a person's last sign-in when their sessions go away
+
+`Last signed in` was `max(sessions.created_at)`, so it disappeared whenever the session rows behind
+it did: on sign-out, on expiry, and when an administrator removed somebody. Restoring them did not
+bring it back, and the person moved to the bottom of the list as somebody who had never signed in.
+The moment of each sign-in is now recorded on the person, so the answer survives all three, and a
+removed person's row shows when they were last here instead of leaving it out. Existing deployments
+are backfilled from whatever sessions they still hold.
+
 ### A message can carry files
 
 Pick them, drag them onto the composer or paste them in: up to eight files on one message, images up

app/src/routes/_authed/admin/people.tsx

@@ -54,7 +54,8 @@ function describe(person: Person): string {
     ? `last signed in ${new Date(person.lastSignedInAt).toLocaleDateString()}`
     : "never signed in";
 
-  if (person.revoked) return `Access removed · ${providers || "no provider"}`;
+  if (person.revoked)
+    return `Access removed · ${providers || "no provider"} · ${when}`;
   if (person.configuredAdmin) {
     return `Administrator by configuration · ${when}`;
   }

server/drizzle/0034_last_signed_in_at.sql

@@ -0,0 +1 @@
+ALTER TABLE "users" ADD COLUMN "last_signed_in_at" timestamp with time zone;

server/drizzle/0035_backfill_last_signed_in_at.sql

@@ -0,0 +1,9 @@
+UPDATE "users" AS u
+SET "last_signed_in_at" = s."last_created"
+FROM (
+  SELECT "user_id", max("created_at") AS "last_created"
+  FROM "sessions"
+  GROUP BY "user_id"
+) AS s
+WHERE s."user_id" = u."id"
+  AND u."last_signed_in_at" IS NULL;