Rebuild agent-builder on a2a-pack 0.1.51

agent.py

@@ -190,7 +190,7 @@ class AgentBuilder(A2AAgent[BuilderConfig, NoAuth]):
                     if isinstance(out, dict):
                         final_state = out
         except Exception as exc:  # noqa: BLE001
-            return {"error": f"build graph failed: {type(exc).__name__}: {exc}"}
+            return {"error": _build_failure_error(exc)}
         finally:
             heartbeat_task.cancel()
             with suppress(asyncio.CancelledError):
@@ -278,4 +278,20 @@ def _find_url(value: Any) -> str | None:
         m = _URL_RE.search(value)
         return m.group(0) if m else None
     return None
+
+
+def _build_failure_error(exc: BaseException) -> str:
+    message = str(exc)
+    lowered = message.lower()
+    if (
+        "budget has been exceeded" in lowered
+        or "budget exceeded" in lowered
+        or "ratelimiterror" in type(exc).__name__.lower()
+        or "rate limit" in lowered
+    ):
+        return (
+            "LLM budget exceeded before deployment; retry with a larger budget "
+            "or a smaller build scope"
+        )
+    return f"build graph failed: {type(exc).__name__}: {exc}"
 # rebuild against a2a-pack 0.1.47 for manifest-backed meta-agent defaults