diff --git a/routes/api.py b/routes/api.py
index 11ce1a3..ee6fdb8 100644
--- a/routes/api.py
+++ b/routes/api.py
@@ -133,7 +133,18 @@ def _fetch_pending_builds_all_towns(c, player_id):
     This allows all towns to build in parallel within a single poll cycle.
     Within each town the oldest-updated command is picked first, so requeued
     commands (updated_at = now) naturally sort behind fresh ones.
+
+    Towns that already have a command in 'executing' state are skipped —
+    this prevents a second build from being dispatched before the first one
+    has reported its result (which was causing commands to pile up in EXECUTING).
     """
+    # Towns that currently have a build already in-flight — don't touch those.
+    executing_rows = c.execute('''
+        SELECT DISTINCT town_id FROM commands
+        WHERE status = 'executing' AND type = 'build' AND player_id = ?
+    ''', (player_id,)).fetchall()
+    busy_towns = {r['town_id'] for r in executing_rows}
+
     # Get every town that has at least one pending build, ordered by
     # which town has been waiting longest (MIN updated_at across its commands).
     town_rows = c.execute('''
@@ -148,6 +159,11 @@ def _fetch_pending_builds_all_towns(c, player_id):
     now = datetime.utcnow().isoformat()
     for town_row in town_rows:
         town_id = town_row['town_id']
+
+        # Skip this town if a build is already executing for it
+        if town_id in busy_towns:
+            continue
+
         row = c.execute('''
             SELECT * FROM commands
             WHERE status = 'pending' AND type = 'build'