diff --git a/run_migrations.py b/run_migrations.py
index 5a98939..d5f3e84 100644
--- a/run_migrations.py
+++ b/run_migrations.py
@@ -71,40 +71,57 @@ def ensure_tracking_table(conn):
 def seed_pre_tracking_migrations(conn):
     """
     Retroactively mark migrations as applied if their schema objects already
-    exist. Required when the tracking table is introduced to a database that
-    was migrated before tracking existed — prevents re-running non-idempotent
-    statements (TimescaleDB policies, triggers, continuous aggregates).
+    exist. Checked on every startup — safe to run repeatedly (ON CONFLICT DO
+    NOTHING). Prevents re-running non-idempotent statements when a second
+    container starts after another has already applied the migration, or when
+    the tracking table is introduced to a database migrated before it existed.
+
+    Sentinel objects per migration:
+      02 — tracksolid.devices table exists
+      03 — position_history.altitude column exists
+      04 — trips.distance_km column exists (renamed from distance_m)
+      05 — tracksolid.device_events table exists (new in 05)
     """
+    checks = [
+        (
+            "02_tracksolid_full_schema_rev.sql",
+            "SELECT 1 FROM information_schema.tables "
+            "WHERE table_schema='tracksolid' AND table_name='devices'",
+        ),
+        (
+            "03_webhook_schema_migration.sql",
+            "SELECT 1 FROM information_schema.columns "
+            "WHERE table_schema='tracksolid' AND table_name='position_history' "
+            "AND column_name='altitude'",
+        ),
+        (
+            "04_bug_fix_migration.sql",
+            "SELECT 1 FROM information_schema.columns "
+            "WHERE table_schema='tracksolid' AND table_name='trips' "
+            "AND column_name='distance_km'",
+        ),
+        (
+            "05_enhancement_migration.sql",
+            "SELECT 1 FROM information_schema.tables "
+            "WHERE table_schema='tracksolid' AND table_name='device_events'",
+        ),
+    ]
+
     seeds = []
-
     with conn.cursor() as cur:
-        # Migration 02: tracksolid.devices is the canonical sentinel table
-        cur.execute("""
-            SELECT 1 FROM information_schema.tables
-            WHERE table_schema = 'tracksolid' AND table_name = 'devices'
-        """)
-        if cur.fetchone():
-            seeds.append("02_tracksolid_full_schema_rev.sql")
-
-        # Migration 03: position_history.altitude column added in this migration
-        cur.execute("""
-            SELECT 1 FROM information_schema.columns
-            WHERE table_schema = 'tracksolid'
-              AND table_name   = 'position_history'
-              AND column_name  = 'altitude'
-        """)
-        if cur.fetchone():
-            seeds.append("03_webhook_schema_migration.sql")
-
-        for filename in seeds:
-            cur.execute("""
-                INSERT INTO tracksolid.schema_migrations (filename)
-                VALUES (%s) ON CONFLICT DO NOTHING
-            """, (filename,))
+        for filename, query in checks:
+            cur.execute(query)
+            if cur.fetchone():
+                cur.execute(
+                    "INSERT INTO tracksolid.schema_migrations (filename) "
+                    "VALUES (%s) ON CONFLICT DO NOTHING",
+                    (filename,),
+                )
+                seeds.append(filename)
 
     conn.commit()
     if seeds:
-        print(f"  Seeded pre-tracking migrations as applied: {', '.join(seeds)}")
+        print(f"  Seeded as applied: {', '.join(seeds)}")
 
 
 def already_applied(conn, filename):