diff --git a/hub/CHANGELOG.md b/hub/CHANGELOG.md
index 688de7ca..8d8cac41 100644
--- a/hub/CHANGELOG.md
+++ b/hub/CHANGELOG.md
@@ -1,3 +1,56 @@
+## v0.108.0 — only the first broken app per hour reached the operator (2026-08-23, R-389)
+
+**The hour is unchanged. The GRAIN is what was wrong.**
+
+`processOperator` keys its 1-hour cooldown on `customerID:eventType`, plus the tier and run suffixes.
+**None of them names an app.** So every app that went down inside the same hour collapsed onto one
+key and only the first was mailed. Measured live on `demo-hp` 2026-08-23: `bookstack` alarmed at
+09:27:51 and was `sent`; `privatebin` alarmed four minutes later and was recorded
+`suppressed — operator cooldown 1h, key=demo-hp:app_start_failed`. **Three apps dying together
+produced one mail.**
+
+The app's identity was already on the wire — `AppDetails{StackName, DisplayName}` serialises as
+`stack_name` — and the hub already made exactly this distinction twice, for backup tiers and for
+backup runs.
+
+### The fix: a third sibling, allow-listed to ONE event type
+
+`cooldownStackSuffix` follows `cooldownTierSuffix` and `cooldownRunSuffix` exactly: guard on the
+substring, unmarshal a one-field struct, return `""` on any doubt. A **separate function**, for the
+reason `cooldownRunSuffix`'s docstring already gives — the existing two keep byte-identical semantics
+for every type that uses them, so R-97a's and R-182's behaviour and their tests are untouched.
+
+**It takes the event type as well as the details, unlike its siblings, and that asymmetry is the whole
+safety property.** `tier` and `run_id` appear only on types that want that grain; `stack_name` does
+not have that property, so a payload-shape rule would have been wrong.
+
+**`perAppCooldownEvents` is a named register with `app_start_failed` and nothing else.** The backup
+family's cooldown is coarse **on purpose** — R-97a and R-182 exist so one full disk sends one digest
+rather than one mail per app. **This is not hypothetical: `crossdrive_failed` is severity `error`,
+reaches the operator leg, and carries `stack_name`** through a different struct (`CrossDriveDetails`,
+not `AppDetails`). A global suffix would have split it into one mail per app, silently.
+
+**`app_start_failed` gets per-app because it has no digest.** There is no `apps_down_run` summarising
+a scan the way `backup_run_failures` summarises a run, so per-app is the only grain available that
+does not lose alarms.
+
+**Fail-soft:** absent, empty or malformed details return `""`, the key degrades to v0.107.0's, and the
+mail still goes. Losing an alarm is worse than mis-routing one.
+
+### Tests
+
+`internal/notify/r389_cooldown_grain_test.go`. Test count **709 → 716**.
+
+Scenario A asserts **two `sent` operator rows in the stored notification log**, not a return value,
+and runs a positive control first — the operator leg must be shown delivering before any count means
+anything. Scenario C's "no other key changed" is an absence claim and carries its own control: the
+test proves it can *see* a key change before reporting that none occurred.
+
+**Red-proofs, both seen failing.** Dropping the suffix from the key reproduces the live symptom
+verbatim (`1 operator mail(s), want 2`, and a suppression row reading `key=c1:app_start_failed`).
+Removing the allow-list splits `crossdrive_failed`, `app_deployed`, `app_removed` and `backup_failed`
+per app — the fence convicting exactly the types it was written for.
+
 ## v0.107.0 — the hub rewrote a severity and said nothing, and the guard for that sat downstream of the rewrite (2026-08-23, R-387)
 
 **One handler, two fields, opposite discipline.** An unknown **event type** is rejected with a loud
diff --git a/manifests/hub.yaml b/manifests/hub.yaml
index a6ebac0f..d27bbd58 100644
--- a/manifests/hub.yaml
+++ b/manifests/hub.yaml
@@ -125,7 +125,7 @@ spec:
     spec:
       containers:
         - name: hub
-          image: gitea.dooplex.hu/admin/felhom-hub:0.107.0
+          image: gitea.dooplex.hu/admin/felhom-hub:0.108.0
           ports:
             - containerPort: 8080
               name: http