Lazy-load concrete renderer classes via PEP 562 __getattr__

renderers/__init__.py

@@ -59,20 +59,51 @@
     Qwen3VLRendererConfig,
     RendererConfig,
 )
-from renderers.deepseek_v3 import DeepSeekV3Renderer
-from renderers.default import DefaultRenderer
-from renderers.glm5 import GLM5Renderer, GLM51Renderer
-from renderers.glm45 import GLM45Renderer
-from renderers.gpt_oss import GptOssRenderer
-from renderers.kimi_k2 import KimiK2Renderer
-from renderers.kimi_k25 import KimiK25Renderer
-from renderers.laguna_xs2 import LagunaXS2Renderer
-from renderers.minimax_m2 import MiniMaxM2Renderer
-from renderers.nemotron3 import Nemotron3Renderer
-from renderers.qwen3 import Qwen3Renderer
-from renderers.qwen3_vl import Qwen3VLRenderer
-from renderers.qwen35 import Qwen35Renderer
-from renderers.qwen36 import Qwen36Renderer
+
+# Concrete renderer classes are lazy-loaded so that consumers needing
+# only the config layer (``RendererConfig`` discriminated union) don't
+# pay the ``transformers`` import cost. Each renderer module does
+# ``from transformers.tokenization_utils import PreTrainedTokenizer``
+# at module level, so eager imports here would drag ``transformers``
+# into every downstream ``import renderers``. ``__getattr__`` (PEP 562)
+# resolves the names on first attribute access, so ``from renderers
+# import DefaultRenderer`` and ``renderers.DefaultRenderer`` both work
+# transparently. ``create_renderer`` doesn't depend on these eager
+# imports — ``renderers.base._populate_registry`` lazy-imports the
+# concrete classes itself when a renderer is instantiated.
+_LAZY_RENDERERS: dict[str, str] = {
+    "DeepSeekV3Renderer": "renderers.deepseek_v3",
+    "DefaultRenderer": "renderers.default",
+    "GLM45Renderer": "renderers.glm45",
+    "GLM51Renderer": "renderers.glm5",
+    "GLM5Renderer": "renderers.glm5",
+    "GptOssRenderer": "renderers.gpt_oss",
+    "KimiK25Renderer": "renderers.kimi_k25",
+    "KimiK2Renderer": "renderers.kimi_k2",
+    "LagunaXS2Renderer": "renderers.laguna_xs2",
+    "MiniMaxM2Renderer": "renderers.minimax_m2",
+    "Nemotron3Renderer": "renderers.nemotron3",
+    "Qwen35Renderer": "renderers.qwen35",
+    "Qwen36Renderer": "renderers.qwen36",
+    "Qwen3Renderer": "renderers.qwen3",
+    "Qwen3VLRenderer": "renderers.qwen3_vl",
+}
+
+
+def __getattr__(name: str):
+    if name in _LAZY_RENDERERS:
+        import importlib
+
+        module = importlib.import_module(_LAZY_RENDERERS[name])
+        value = getattr(module, name)
+        globals()[name] = value  # cache for subsequent lookups
+        return value
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
+
+
+def __dir__() -> list[str]:
+    return sorted(set(globals().keys()) | set(_LAZY_RENDERERS))
+
 
 __all__ = [
     "AutoRendererConfig",