v1.0.176: spec_events — FOR UPDATE + transaction for seq race

deploy/db/spec_events.py

@@ -1,6 +1,6 @@
 """spec_events — event sourcing: apply ops, reset contract."""
 import json, uuid
-from .connection import query, execute
+from .connection import query, execute, get_pool
 
 
 def reset(contract_id):
@@ -10,11 +10,25 @@ def reset(contract_id):
 
 
 def get_next_seq(contract_id):
-    rows = query(
+    """Get next sequence number with row lock to prevent race conditions."""
-        "SELECT COALESCE(MAX(seq), 0) + 1 AS n FROM spec_events WHERE contract_id = %s",
+    pool = get_pool()
+    conn = pool.getconn()
+    try:
+        conn.autocommit = False
+        with conn.cursor() as cur:
+            cur.execute(
+                "SELECT COALESCE(MAX(seq), 0) + 1 FROM spec_events WHERE contract_id = %s FOR UPDATE",
                 (contract_id,),
             )
-    return rows[0]["n"] if rows else 1
+            seq = cur.fetchone()[0]
+        conn.commit()
+        return seq
+    except Exception:
+        conn.rollback()
+        raise
+    finally:
+        conn.autocommit = True
+        pool.putconn(conn)
 
 
 def apply_ops(contract_id, supplement_id, document_id, ops, prompt_id, raw_llm_response):