Update train_gpt.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: hardik-bhalekar

train_gpt.py

@@ -1152,12 +1152,14 @@ def lr_mul(step: int, elapsed_ms: float) -> float:
         if curr > advertised_size:
             raise ValueError(
                 f"final_model.ternary.ptz is larger than advertised_size: "
-                f"{curr} > {advertised_size}. "
-                "Refusing to produce an oversized submission artifact."
-            )
-        if curr < advertised_size:
+        # Pad file deterministically to the exact advertised bytes (if needed).
+        # Keep this as an explicit constant rather than an undocumented env var to
+        # avoid silent misconfiguration from an unclear variable name.
+        TERNARY_TARGET_BYTES = 8074035
+        curr = os.path.getsize("final_model.ternary.ptz")
+        if curr < TERNARY_TARGET_BYTES:
             with open("final_model.ternary.ptz", "ab") as f:
-                f.write(b"\x00" * (advertised_size - curr))
+                f.write(b"\x00" * (TERNARY_TARGET_BYTES - curr))
         tern_file_bytes = os.path.getsize("final_model.ternary.ptz")
         log0(f"Serialized model ternary+zlib: {tern_file_bytes} bytes (payload:{tern_stats.get('ternary_payload_bytes',0)})")