diff --git a/tools/fill_domain_ltd_by_prefix.py b/tools/fill_domain_ltd_by_prefix.py
new file mode 100644
index 0000000..309beb3
--- /dev/null
+++ b/tools/fill_domain_ltd_by_prefix.py
@@ -0,0 +1,66 @@
+"""Remplit servers.domain_ltd par convention SANEF (2eme lettre du hostname).
+
+Regle:
+  v[p|i]* -> sanef.groupe   (prod/integration)
+  v[r|t|d]* -> sanef-rec.fr (recette/test/dev)
+
+Applique UNIQUEMENT aux serveurs dont domain_ltd est vide (NULL ou '').
+
+Usage:
+    python tools/fill_domain_ltd_by_prefix.py [--dry-run]
+"""
+import os
+import argparse
+from sqlalchemy import create_engine, text
+
+DATABASE_URL = os.getenv("DATABASE_URL_DEMO") or os.getenv("DATABASE_URL") \
+    or "postgresql://patchcenter:PatchCenter2026!@localhost:5432/patchcenter_demo"
+
+RULES = {
+    "p": "sanef.groupe",
+    "i": "sanef.groupe",
+    "r": "sanef-rec.fr",
+    "t": "sanef-rec.fr",
+    "d": "sanef-rec.fr",
+}
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--dry-run", action="store_true")
+    args = parser.parse_args()
+
+    engine = create_engine(DATABASE_URL)
+    print(f"[INFO] DB: {DATABASE_URL.split('@')[-1]}")
+    conn = engine.connect().execution_options(isolation_level="AUTOCOMMIT")
+
+    rows = conn.execute(text("""
+        SELECT id, hostname FROM servers
+        WHERE (domain_ltd IS NULL OR domain_ltd = '')
+        ORDER BY hostname
+    """)).fetchall()
+    print(f"[INFO] {len(rows)} serveurs sans domain_ltd")
+
+    updated = skipped = 0
+    for r in rows:
+        h = (r.hostname or "").lower()
+        if len(h) < 2 or h[0] != "v":
+            skipped += 1
+            continue
+        domain = RULES.get(h[1])
+        if not domain:
+            skipped += 1
+            continue
+        if args.dry_run:
+            print(f"  DRY: {r.hostname:25s} -> {domain}")
+        else:
+            conn.execute(text("UPDATE servers SET domain_ltd=:d WHERE id=:sid"),
+                         {"d": domain, "sid": r.id})
+        updated += 1
+
+    conn.close()
+    print(f"\n[DONE] Maj: {updated} | Skip (hors regle): {skipped}")
+
+
+if __name__ == "__main__":
+    main()