From 02c3b8254e0ec23aa7867d87fcc68004b8533f10 Mon Sep 17 00:00:00 2001
From: Ralf Kistner <ralf@journeyapps.com>
Date: Thu, 17 Jul 2025 13:39:57 +0200
Subject: [PATCH 1/4] Add diagnostic message if no commit is performed on the
 active replication stream.

---
 packages/service-core/src/api/diagnostics.ts | 31 ++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/packages/service-core/src/api/diagnostics.ts b/packages/service-core/src/api/diagnostics.ts
index a4c6af3c0..36e2be824 100644
--- a/packages/service-core/src/api/diagnostics.ts
+++ b/packages/service-core/src/api/diagnostics.ts
@@ -134,6 +134,37 @@ export async function getSyncRulesStatus(
     })
   );
 
+  if (live_status && status?.active) {
+    // Check replication lag for active sync rules.
+    if (sync_rules.last_checkpoint_ts == null && sync_rules.last_keepalive_ts == null) {
+      errors.push({
+        level: 'warning',
+        message: 'No checkpoint found, cannot calculate replication lag'
+      });
+    } else {
+      const lastTime = Math.max(
+        sync_rules.last_checkpoint_ts?.getTime() ?? 0,
+        sync_rules.last_keepalive_ts?.getTime() ?? 0
+      );
+      const lagSeconds = Math.round((Date.now() - lastTime) / 1000);
+      // On idle instances, keepalive messages are only persisted every 60 seconds.
+      // So we use 2 minutes as a threshold for warnings, and 15 minutes for critical.
+      // The replication lag metric should give a more granular value, but that is not available directly
+      // in the API containers used for diagnostics, and this should give a good enough indication.
+      if (lagSeconds > 15 * 60) {
+        errors.push({
+          level: 'fatal',
+          message: `No replicated commit in more than ${lagSeconds}s`
+        });
+      } else if (lagSeconds > 120) {
+        errors.push({
+          level: 'warning',
+          message: `No replicated commit in more than ${lagSeconds}s`
+        });
+      }
+    }
+  }
+
   return {
     content: include_content ? sync_rules.sync_rules_content : undefined,
     connections: [

From e570317c83f0b4fa148b9918ca81704580aaac43 Mon Sep 17 00:00:00 2001
From: Ralf Kistner <ralf@journeyapps.com>
Date: Thu, 17 Jul 2025 13:40:14 +0200
Subject: [PATCH 2/4] For postgres, ping every minute.

---
 packages/service-core/src/replication/AbstractReplicator.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/service-core/src/replication/AbstractReplicator.ts b/packages/service-core/src/replication/AbstractReplicator.ts
index b102350d9..e76debe73 100644
--- a/packages/service-core/src/replication/AbstractReplicator.ts
+++ b/packages/service-core/src/replication/AbstractReplicator.ts
@@ -10,8 +10,8 @@ import { AbstractReplicationJob } from './AbstractReplicationJob.js';
 import { ErrorRateLimiter } from './ErrorRateLimiter.js';
 import { ConnectionTestResult } from './ReplicationModule.js';
 
-// 5 minutes
-const PING_INTERVAL = 1_000_000_000n * 300n;
+// 1 minute
+const PING_INTERVAL = 1_000_000_000n * 60n;
 
 export interface CreateJobOptions {
   lock: storage.ReplicationLock;

From 0c224d0839ca4158ba7cffa50362f46e0469f5ce Mon Sep 17 00:00:00 2001
From: Ralf Kistner <ralf@journeyapps.com>
Date: Thu, 17 Jul 2025 13:41:15 +0200
Subject: [PATCH 3/4] Add changeset.

---
 .changeset/ninety-points-provide.md | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 .changeset/ninety-points-provide.md

diff --git a/.changeset/ninety-points-provide.md b/.changeset/ninety-points-provide.md
new file mode 100644
index 000000000..cce194576
--- /dev/null
+++ b/.changeset/ninety-points-provide.md
@@ -0,0 +1,6 @@
+---
+'@powersync/service-core': minor
+'@powersync/service-image': minor
+---
+
+Report lack of commits or keepalives as issues in the diagnostics api.

From 81f679ca2a6fce75261a13935a57dd0f4cc7e8bc Mon Sep 17 00:00:00 2001
From: Ralf Kistner <ralf@journeyapps.com>
Date: Mon, 21 Jul 2025 17:37:02 +0200
Subject: [PATCH 4/4] Disable check for mysql for now.

---
 packages/service-core/src/api/diagnostics.ts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/packages/service-core/src/api/diagnostics.ts b/packages/service-core/src/api/diagnostics.ts
index 36e2be824..6a1eaab40 100644
--- a/packages/service-core/src/api/diagnostics.ts
+++ b/packages/service-core/src/api/diagnostics.ts
@@ -134,8 +134,9 @@ export async function getSyncRulesStatus(
     })
   );
 
-  if (live_status && status?.active) {
+  if (live_status && status?.active && sourceConfig.type != 'mysql') {
     // Check replication lag for active sync rules.
+    // Right now we exclude mysql, since it we don't have consistent keepalives for it.
     if (sync_rules.last_checkpoint_ts == null && sync_rules.last_keepalive_ts == null) {
       errors.push({
         level: 'warning',