fix(fal_ai): don't claim n on models that make one image

Bria and Recraft v3 listed n in get_supported_openai_params, then hit
'continue' in map_openai_params with a comment saying the model can't do
multiple images. n=3 came back as one image and nothing said why.

Not listing it routes n through the normal unsupported-param path: an error
naming the param, or a quiet skip under drop_params.

nano_banana and ideogram_v3 do map n to num_images and are untouched.

litellm/llms/fal_ai/image_generation/bria_transformation.py

@@ -33,7 +33,6 @@ class FalAIBriaConfig(FalAIBaseConfig):
         Get supported OpenAI parameters for Bria 3.2.
         """
         return [
-            "n",
             "response_format",
             "size",
         ]
@@ -51,7 +50,6 @@ class FalAIBriaConfig(FalAIBaseConfig):
         Mappings:
         - size -> aspect_ratio (1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9)
         - response_format -> ignored (Bria returns URLs)
-        - n -> ignored (Bria doesn't support multiple images in one call)
         """
         supported_params = self.get_supported_openai_params(model)
 
@@ -71,9 +69,6 @@ class FalAIBriaConfig(FalAIBaseConfig):
                     if k == "response_format":
                         # Bria always returns URLs, so we can ignore this
                         continue
-                    elif k == "n":
-                        # Bria doesn't support multiple images, ignore
-                        continue
                     elif k == "size":
                         # Map OpenAI size format to Bria aspect ratio
                         mapped_value = self._map_aspect_ratio(mapped_value)

litellm/llms/fal_ai/image_generation/recraft_v3_transformation.py

@@ -33,7 +33,6 @@ class FalAIRecraftV3Config(FalAIBaseConfig):
         Get supported OpenAI parameters for Recraft v3.
         """
         return [
-            "n",
             "response_format",
             "size",
         ]
@@ -51,7 +50,6 @@ class FalAIRecraftV3Config(FalAIBaseConfig):
         Mappings:
         - size -> image_size (can be preset or custom width/height)
         - response_format -> ignored (Recraft returns URLs)
-        - n -> ignored (Recraft doesn't support multiple images)
         """
         supported_params = self.get_supported_openai_params(model)
 
@@ -71,9 +69,6 @@ class FalAIRecraftV3Config(FalAIBaseConfig):
                     if k == "response_format":
                         # Recraft always returns URLs, so we can ignore this
                         continue
-                    elif k == "n":
-                        # Recraft doesn't support multiple images, ignore
-                        continue
                     elif k == "size":
                         # Map OpenAI size format to Recraft image_size
                         mapped_value = self._map_image_size(mapped_value)

tests/test_litellm/llms/fal_ai/image_generation/test_fal_ai_n_param.py

@@ -0,0 +1,109 @@
+"""Bria and Recraft v3 generate one image per call.
+
+Both used to list "n" as supported and then skip over it, so n=3 returned a
+single image and the caller was never told. Not listing it lets the normal
+unsupported-param path do its job.
+
+Contrast: nano_banana and ideogram_v3 do map n to num_images, see
+test_fal_ai_nano_banana_transformation.py.
+"""
+
+import pytest
+
+import litellm
+from litellm.llms.fal_ai.image_generation.bria_transformation import FalAIBriaConfig
+from litellm.llms.fal_ai.image_generation.recraft_v3_transformation import (
+    FalAIRecraftV3Config,
+)
+
+CONFIGS = [
+    (FalAIBriaConfig, "bria/text-to-image/3.2"),
+    (FalAIRecraftV3Config, "fal-ai/recraft/v3/text-to-image"),
+]
+
+
+@pytest.mark.parametrize("config_cls,model", CONFIGS)
+def test_n_not_claimed(config_cls, model):
+    assert "n" not in config_cls().get_supported_openai_params(model)
+
+
+@pytest.mark.parametrize("config_cls,model", CONFIGS)
+def test_n_raises_instead_of_being_skipped(config_cls, model):
+    with pytest.raises(ValueError, match="not supported"):
+        config_cls().map_openai_params(
+            non_default_params={"n": 3},
+            optional_params={},
+            model=model,
+            drop_params=False,
+        )
+
+
+@pytest.mark.parametrize("config_cls,model", CONFIGS)
+def test_n_still_droppable(config_cls, model):
+    params = config_cls().map_openai_params(
+        non_default_params={"n": 3},
+        optional_params={},
+        model=model,
+        drop_params=True,
+    )
+    assert "n" not in params
+    assert "num_images" not in params
+
+
+@pytest.mark.parametrize("config_cls,model", CONFIGS)
+def test_size_still_maps(config_cls, model):
+    """The params these models do serve must keep working."""
+    params = config_cls().map_openai_params(
+        non_default_params={"size": "1024x1024"},
+        optional_params={},
+        model=model,
+        drop_params=False,
+    )
+    # bria calls it aspect_ratio, recraft calls it image_size
+    assert params in ({"aspect_ratio": "1:1"}, {"image_size": "square_hd"})
+
+
+@pytest.mark.parametrize("config_cls,model", CONFIGS)
+def test_n_raises_through_get_optional_params_image_gen(config_cls, model):
+    """The path a caller actually takes.
+
+    map_openai_params is not reached with an unsupported param: the check in
+    get_optional_params_image_gen runs first and raises UnsupportedParamsError.
+    Testing only the config in isolation would miss which error users see.
+    """
+    from litellm.utils import get_optional_params_image_gen
+
+    with pytest.raises(litellm.UnsupportedParamsError, match="`n` is not supported"):
+        get_optional_params_image_gen(
+            model=model,
+            custom_llm_provider="fal_ai",
+            provider_config=config_cls(),
+            n=3,
+        )
+
+
+@pytest.mark.parametrize("config_cls,model", CONFIGS)
+def test_n_dropped_end_to_end_with_drop_params(config_cls, model):
+    from litellm.utils import get_optional_params_image_gen
+
+    params = get_optional_params_image_gen(
+        model=model,
+        custom_llm_provider="fal_ai",
+        provider_config=config_cls(),
+        n=3,
+        drop_params=True,
+    )
+    assert params == {}
+
+
+@pytest.mark.parametrize("config_cls,model", CONFIGS)
+def test_size_still_maps_end_to_end(config_cls, model):
+    from litellm.utils import get_optional_params_image_gen
+
+    params = get_optional_params_image_gen(
+        model=model,
+        custom_llm_provider="fal_ai",
+        provider_config=config_cls(),
+        size="1024x1024",
+    )
+    assert params in ({"aspect_ratio": "1:1"}, {"image_size": "square_hd"})