diff --git a/CHANGELOG.md b/CHANGELOG.md
index 627d002..2481280 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,23 @@
+## romm gets 768M — 5.3.0 does not fit in 512M (2026-09-22, R-635)
+
+**No `image:` line moved, so no `catalog_since` moved.** `romm` 512M -> **768M**; the header and
+`.felhom.yml` totals follow (1024M -> 1280M).
+
+**Measured on demo-hp, not reasoned about.** `romm 5.0.0 -> 5.3.0` was promoted that morning after
+the edge was proven on the scratch guest, and the guarded Update on demo-hp reached `done` in 74.8 s.
+It ran clean for two hours. Then: `OOMKilled: true`, **4,530** `Worker … was sent SIGKILL! Perhaps
+out of memory?` in six hours, the container pinned at 457 MiB of its 512 MiB limit, **~500% CPU** in
+a permanent restart storm, host load average **5.2 while otherwise idle**.
+
+**Two things this cost that a bigger number alone does not fix, both recorded in R-635.** The update
+read `done` and the app read `running` throughout, because nginx answers `GET /` with 200 while the
+gunicorn workers behind it are being killed — the probe is right, the port is right, and the green is
+still false. And nothing alarmed: OOM signals are invisible inside an LXC guest (R-528), and a
+running-but-thrashing app is not "down". **The operator heard the fans. That was the detector.**
+
+768M is a first measured step, not a final answer — the soak that follows this entry is what settles
+whether it is enough.
+
 ## The probe gate now runs in CI's own degraded mode (2026-09-22, R-618)
 
 **Caught by checking the push's CI run by job id, not by assuming it went green.** Job **877** on
diff --git a/templates/romm/.felhom.yml b/templates/romm/.felhom.yml
index 607e12f..cf4f22f 100644
--- a/templates/romm/.felhom.yml
+++ b/templates/romm/.felhom.yml
@@ -15,7 +15,7 @@ catalog_since: "2026-09-22"
 # --- Resource hints (displayed on deploy screen) ---
 resources:
   mem_request: "300M"
-  mem_limit: "1024M"
+  mem_limit: "1280M"
   pi_compatible: false
   needs_hdd: true
 
diff --git a/templates/romm/docker-compose.yml b/templates/romm/docker-compose.yml
index 97131cb..f09121f 100644
--- a/templates/romm/docker-compose.yml
+++ b/templates/romm/docker-compose.yml
@@ -1,7 +1,7 @@
 # ROMM - ROM Manager for Game Libraries
 # Domain: ${SUBDOMAIN}.${DOMAIN}
 # Database: MariaDB + Redis
-# RAM: ~300MB (mem_limit: 1024M total — romm 512M + mariadb 384M + redis 128M) | Pi-compatible: No (MariaDB + heavy)
+# RAM: ~300MB (mem_limit: 1280M total — romm 768M + mariadb 384M + redis 128M) | Pi-compatible: No (MariaDB + heavy)
 #
 # Environment variables:
 #   DOMAIN                  - Your domain (e.g., demo-felhom.eu)
@@ -72,7 +72,11 @@ services:
     deploy:
       resources:
         limits:
-          memory: 512M
+          # 768M, not 512M: romm 5.3.0 does not fit in 512M. Measured on demo-hp 2026-09-22 —
+          # OOMKilled true, 4,530 gunicorn worker SIGKILLs in six hours, ~500% CPU in a permanent
+          # restart storm, while the web front end still answered 200 so the update read `done`
+          # (R-635). 5.0.0 did fit; the version moved and the limit did not.
+          memory: 768M
     healthcheck:
       test: ["CMD", "wget", "--spider", "-q", "http://127.0.0.1:8080/"]
       interval: 30s