From 234b3be61343ffafedf489c9ace8dee8adc90983 Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sat, 18 Jul 2026 18:41:46 +0000
Subject: [PATCH 01/15] init

---
 .../modular_pipelines/modular_pipeline.py     |   4 +
 .../modular_pipeline_utils.py                 |  64 ++++----
 .../test_conditional_pipeline_blocks.py       | 153 ++++++++++++++++++
 3 files changed, 193 insertions(+), 28 deletions(-)

diff --git a/src/diffusers/modular_pipelines/modular_pipeline.py b/src/diffusers/modular_pipelines/modular_pipeline.py
index d43825860d8e..f81d3233f7a7 100644
--- a/src/diffusers/modular_pipelines/modular_pipeline.py
+++ b/src/diffusers/modular_pipelines/modular_pipeline.py
@@ -502,6 +502,10 @@ def get_block_state(self, state: PipelineState) -> dict:
         for input_param in state_inputs:
             if input_param.name:
                 value = state.get(input_param.name)
+                if value is None:
+                    # a ConditionalPipelineBlocks parent merges disagreeing sub-block defaults to None at the
+                    # pipeline level (see combine_inputs); each block falls back to its own declared default here
+                    value = input_param.default
                 if input_param.required and value is None:
                     raise ValueError(f"Required input '{input_param.name}' is missing")
                 elif value is not None or (value is None and input_param.name not in data):
diff --git a/src/diffusers/modular_pipelines/modular_pipeline_utils.py b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
index 7aa61c55ef1f..576f80b84f49 100644
--- a/src/diffusers/modular_pipelines/modular_pipeline_utils.py
+++ b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
@@ -14,9 +14,8 @@
 
 import inspect
 import re
-import warnings
 from collections import OrderedDict
-from dataclasses import dataclass, field
+from dataclasses import dataclass, field, replace
 from types import UnionType
 from typing import Any, Literal, Type, Union, get_args, get_origin
 
@@ -556,6 +555,10 @@ class InputParam:
     description: str = ""
     kwargs_type: str = None
     metadata: dict[str, Any] = None
+    # set by `combine_inputs` when sub-blocks of a ConditionalPipelineBlocks declare different defaults for this
+    # input: maps block name -> that block's declared default; `default` is None in that case and each block
+    # resolves its own default at runtime in `get_block_state`
+    defaults_by_block: dict[str, Any] = None
 
     def __repr__(self):
         return f"<{self.name}: {'required' if self.required else 'optional'}, default={self.default}>"
@@ -764,12 +767,13 @@ def wrap_text(text, indent, max_length):
         param_str += "):"
 
         # Add description on a new line with additional indentation and wrapping
-        if param.description:
-            desc = re.sub(r"\[(.*?)\]\((https?://[^\s\)]+)\)", r"[\1](\2)", param.description)
-            wrapped_desc = wrap_text(desc, desc_indent, max_line_length)
-            param_str += f"\n{desc_indent}{wrapped_desc}"
-        else:
-            param_str += f"\n{desc_indent}TODO: Add description."
+        desc = param.description if param.description else "TODO: Add description."
+        if getattr(param, "defaults_by_block", None):
+            per_block = ", ".join(f"{v} (`{block}`)" for block, v in param.defaults_by_block.items())
+            desc = f"{desc} Default depends on the selected block: {per_block}."
+        desc = re.sub(r"\[(.*?)\]\((https?://[^\s\)]+)\)", r"[\1](\2)", desc)
+        wrapped_desc = wrap_text(desc, desc_indent, max_line_length)
+        param_str += f"\n{desc_indent}{wrapped_desc}"
 
         formatted_params.append(param_str)
 
@@ -838,6 +842,9 @@ def get_type_str(type_hint):
         param_str += ")"
 
         desc = param.description if param.description else "No description provided"
+        if getattr(param, "defaults_by_block", None):
+            per_block = ", ".join(f"`{v}` (`{block}`)" for block, v in param.defaults_by_block.items())
+            desc = f"{desc} Default depends on the selected block: {per_block}."
         param_str += f": {desc}"
         lines.append(param_str)
 
@@ -1102,9 +1109,10 @@ def _accumulate(mapping: dict[str, Any]):
 
 def combine_inputs(*named_input_lists: list[tuple[str, list[InputParam]]]) -> list[InputParam]:
     """
-    Combines multiple lists of InputParam objects from different blocks. For duplicate inputs, updates only if current
-    default value is None and new default value is not None. Warns if multiple non-None default values exist for the
-    same input.
+    Combines multiple lists of InputParam objects from different blocks. Duplicate inputs keep the first occurrence.
+    If duplicate inputs declare different defaults, the combined input's default is None and the per-block defaults
+    are recorded in `defaults_by_block`; each block resolves its own default at runtime in `get_block_state`, and the
+    docstring formatters render the per-block defaults.
 
     Args:
         named_input_lists: List of tuples containing (block_name, input_param_list) pairs
@@ -1113,7 +1121,7 @@ def combine_inputs(*named_input_lists: list[tuple[str, list[InputParam]]]) -> li
         List[InputParam]: Combined list of unique InputParam objects
     """
     combined_dict = {}  # name -> InputParam
-    value_sources = {}  # name -> block_name
+    defaults_by_block = {}  # name -> {block_name: default}
 
     for block_name, inputs in named_input_lists:
         for input_param in inputs:
@@ -1121,24 +1129,24 @@ def combine_inputs(*named_input_lists: list[tuple[str, list[InputParam]]]) -> li
                 input_name = "*_" + input_param.kwargs_type
             else:
                 input_name = input_param.name
-            if input_name in combined_dict:
-                current_param = combined_dict[input_name]
-                if (
-                    current_param.default is not None
-                    and input_param.default is not None
-                    and current_param.default != input_param.default
-                ):
-                    warnings.warn(
-                        f"Multiple different default values found for input '{input_name}': "
-                        f"{current_param.default} (from block '{value_sources[input_name]}') and "
-                        f"{input_param.default} (from block '{block_name}'). Using {current_param.default}."
-                    )
-                if current_param.default is None and input_param.default is not None:
-                    combined_dict[input_name] = input_param
-                    value_sources[input_name] = block_name
+
+            if input_param.defaults_by_block:
+                # nested conditional block: prefix its block names with the sub-block name
+                new_defaults = {f"{block_name}.{k}": v for k, v in input_param.defaults_by_block.items()}
             else:
+                new_defaults = {block_name: input_param.default}
+
+            if input_name not in combined_dict:
                 combined_dict[input_name] = input_param
-                value_sources[input_name] = block_name
+                defaults_by_block[input_name] = new_defaults
+                continue
+
+            defaults_by_block[input_name].update(new_defaults)
+            defaults = list(defaults_by_block[input_name].values())
+            if any(d != defaults[0] for d in defaults[1:]):
+                combined_dict[input_name] = replace(
+                    combined_dict[input_name], default=None, defaults_by_block=dict(defaults_by_block[input_name])
+                )
 
     return list(combined_dict.values())
 
diff --git a/tests/modular_pipelines/test_conditional_pipeline_blocks.py b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
index fa5f64f8b31b..b11afdf8900b 100644
--- a/tests/modular_pipelines/test_conditional_pipeline_blocks.py
+++ b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
@@ -13,12 +13,16 @@
 # limitations under the License.
 
 
+import pytest
+
 from diffusers.modular_pipelines import (
     AutoPipelineBlocks,
     ConditionalPipelineBlocks,
     InputParam,
     ModularPipelineBlocks,
+    OutputParam,
 )
+from diffusers.modular_pipelines.modular_pipeline_utils import combine_inputs
 
 
 class TextToImageBlock(ModularPipelineBlocks):
@@ -240,3 +244,152 @@ def test_sub_block_types(self):
     def test_description(self):
         blocks = ConditionalImageBlocks()
         assert "Conditional" in blocks.description
+
+
+class PlainVideoBlock(ModularPipelineBlocks):
+    model_name = "video"
+
+    @property
+    def inputs(self):
+        return [
+            InputParam(name="prompt"),
+            InputParam(name="num_frames", type_hint=int, default=189, description="Number of frames to generate."),
+        ]
+
+    @property
+    def intermediate_outputs(self):
+        return [OutputParam(name="resolved_num_frames")]
+
+    @property
+    def description(self):
+        return "plain video workflow: uses its declared num_frames default"
+
+    def __call__(self, components, state):
+        block_state = self.get_block_state(state)
+        block_state.resolved_num_frames = block_state.num_frames
+        self.set_block_state(state, block_state)
+        return components, state
+
+
+class ActionVideoBlock(ModularPipelineBlocks):
+    model_name = "video"
+
+    @property
+    def inputs(self):
+        return [
+            InputParam(name="prompt"),
+            InputParam(name="action"),
+            InputParam(name="num_frames", type_hint=int, default=None, description="Number of frames to generate."),
+        ]
+
+    @property
+    def intermediate_outputs(self):
+        return [OutputParam(name="resolved_num_frames")]
+
+    @property
+    def description(self):
+        return "action video workflow: num_frames must not be passed, it is derived from action"
+
+    def __call__(self, components, state):
+        block_state = self.get_block_state(state)
+        if block_state.num_frames is not None:
+            raise ValueError("`num_frames` has to be None if `action` is provided.")
+        block_state.resolved_num_frames = block_state.action + 1
+        self.set_block_state(state, block_state)
+        return components, state
+
+
+class SingleFrameBlock(ModularPipelineBlocks):
+    model_name = "video"
+
+    @property
+    def inputs(self):
+        return [
+            InputParam(name="prompt"),
+            InputParam(name="image"),
+            InputParam(name="num_frames", type_hint=int, default=1, description="Number of frames to generate."),
+        ]
+
+    @property
+    def intermediate_outputs(self):
+        return [OutputParam(name="resolved_num_frames")]
+
+    @property
+    def description(self):
+        return "single frame workflow"
+
+    def __call__(self, components, state):
+        block_state = self.get_block_state(state)
+        block_state.resolved_num_frames = block_state.num_frames
+        self.set_block_state(state, block_state)
+        return components, state
+
+
+class AutoVideoBlocks(AutoPipelineBlocks):
+    block_classes = [ActionVideoBlock, PlainVideoBlock]
+    block_names = ["action", "plain"]
+    block_trigger_inputs = ["action", None]
+
+    @property
+    def description(self):
+        return "Auto video blocks: runs the action workflow when `action` is provided, plain otherwise"
+
+
+class NestedVideoBlocks(ConditionalPipelineBlocks):
+    block_classes = [SingleFrameBlock, AutoVideoBlocks]
+    block_names = ["image", "video"]
+    block_trigger_inputs = ["image"]
+    default_block_name = "video"
+
+    @property
+    def description(self):
+        return "Nested conditional blocks: single frame when `image` is provided, video otherwise"
+
+    def select_block(self, image=None) -> str | None:
+        if image is not None:
+            return "image"
+        return None
+
+
+class TestConditionalBlocksBranchDefaults:
+    def test_conflicting_defaults_merge_to_none(self):
+        merged = {p.name: p for p in AutoVideoBlocks().inputs}["num_frames"]
+        assert merged.default is None
+        assert merged.defaults_by_block == {"action": None, "plain": 189}
+
+    def test_agreeing_defaults_stay_untouched(self):
+        combined = combine_inputs(
+            ("a", [InputParam(name="x", default=5)]),
+            ("b", [InputParam(name="x", default=5)]),
+        )
+        assert combined[0].default == 5
+        assert combined[0].defaults_by_block is None
+
+    def test_default_branch_resolves_own_default(self):
+        pipe = AutoVideoBlocks().init_pipeline()
+        state = pipe(prompt="p")
+        assert state.get("resolved_num_frames") == 189
+
+    def test_sentinel_branch_not_polluted_by_sibling_default(self):
+        pipe = AutoVideoBlocks().init_pipeline()
+        state = pipe(prompt="p", action=8)
+        assert state.get("resolved_num_frames") == 9
+
+    def test_sentinel_branch_rejects_explicit_value(self):
+        pipe = AutoVideoBlocks().init_pipeline()
+        with pytest.raises(ValueError, match="has to be None"):
+            pipe(prompt="p", action=8, num_frames=10)
+
+    def test_standalone_branch_keeps_default(self):
+        pipe = PlainVideoBlock().init_pipeline()
+        state = pipe(prompt="p")
+        assert state.get("resolved_num_frames") == 189
+
+    def test_doc_renders_per_block_defaults(self):
+        doc = " ".join(AutoVideoBlocks().doc.split())
+        assert "Default depends on the selected block: None (`action`), 189 (`plain`)." in doc
+
+    def test_nested_defaults_prefixed_with_sub_block_name(self):
+        merged = {p.name: p for p in NestedVideoBlocks().inputs}["num_frames"]
+        assert merged.default is None
+        assert merged.defaults_by_block == {"image": 1, "video.action": None, "video.plain": 189}

From f3fda64fd9d4545c6572bfc0e16629853f402ecb Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sat, 18 Jul 2026 23:05:49 +0000
Subject: [PATCH 02/15] Ensure branch-specific input defaults in
 ConditionalPipelineBlocks

When sibling blocks of a ConditionalPipelineBlocks declare different
defaults for the same input, combine_inputs now merges the default to
None and records the per-block defaults in a new
InputParam.defaults_by_block field, instead of silently promoting the
non-None default. get_block_state falls back to the block's own declared
default when the state value is None, so each branch resolves its own
default when it actually runs and a branch using None as a "user didn't
pass this" sentinel is no longer polluted by a sibling's default.

Docstrings render conflicted defaults as e.g. "defaults to None or 189,
depending on the workflow".

Fixes #14132

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../modular_pipeline_utils.py                 | 20 +++++++++++--------
 .../test_conditional_pipeline_blocks.py       |  2 +-
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/diffusers/modular_pipelines/modular_pipeline_utils.py b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
index 576f80b84f49..c2ffe2ac359f 100644
--- a/src/diffusers/modular_pipelines/modular_pipeline_utils.py
+++ b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
@@ -762,15 +762,17 @@ def wrap_text(text, indent, max_length):
         if hasattr(param, "required"):
             if not param.required:
                 param_str += ", *optional*"
-                if param.default is not None:
+                if getattr(param, "defaults_by_block", None):
+                    distinct_defaults = list(dict.fromkeys(param.defaults_by_block.values()))
+                    param_str += (
+                        f", defaults to {' or '.join(str(v) for v in distinct_defaults)}, depending on the workflow"
+                    )
+                elif param.default is not None:
                     param_str += f", defaults to {param.default}"
         param_str += "):"
 
         # Add description on a new line with additional indentation and wrapping
         desc = param.description if param.description else "TODO: Add description."
-        if getattr(param, "defaults_by_block", None):
-            per_block = ", ".join(f"{v} (`{block}`)" for block, v in param.defaults_by_block.items())
-            desc = f"{desc} Default depends on the selected block: {per_block}."
         desc = re.sub(r"\[(.*?)\]\((https?://[^\s\)]+)\)", r"[\1](\2)", desc)
         wrapped_desc = wrap_text(desc, desc_indent, max_line_length)
         param_str += f"\n{desc_indent}{wrapped_desc}"
@@ -837,14 +839,16 @@ def get_type_str(type_hint):
 
         if hasattr(param, "required") and not param.required:
             param_str += ", *optional*"
-            if param.default is not None:
+            if getattr(param, "defaults_by_block", None):
+                distinct_defaults = list(dict.fromkeys(param.defaults_by_block.values()))
+                param_str += (
+                    f", defaults to {' or '.join(f'`{v}`' for v in distinct_defaults)}, depending on the workflow"
+                )
+            elif param.default is not None:
                 param_str += f", defaults to `{param.default}`"
         param_str += ")"
 
         desc = param.description if param.description else "No description provided"
-        if getattr(param, "defaults_by_block", None):
-            per_block = ", ".join(f"`{v}` (`{block}`)" for block, v in param.defaults_by_block.items())
-            desc = f"{desc} Default depends on the selected block: {per_block}."
         param_str += f": {desc}"
         lines.append(param_str)
 
diff --git a/tests/modular_pipelines/test_conditional_pipeline_blocks.py b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
index b11afdf8900b..2ae173619933 100644
--- a/tests/modular_pipelines/test_conditional_pipeline_blocks.py
+++ b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
@@ -387,7 +387,7 @@ def test_standalone_branch_keeps_default(self):
 
     def test_doc_renders_per_block_defaults(self):
         doc = " ".join(AutoVideoBlocks().doc.split())
-        assert "Default depends on the selected block: None (`action`), 189 (`plain`)." in doc
+        assert "num_frames (`int`, *optional*, defaults to None or 189, depending on the workflow):" in doc
 
     def test_nested_defaults_prefixed_with_sub_block_name(self):
         merged = {p.name: p for p in NestedVideoBlocks().inputs}["num_frames"]

From c3b1c58b4f4db5b3af2cd06be6880f2a6025a7a3 Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sat, 18 Jul 2026 23:28:44 +0000
Subject: [PATCH 03/15] =?UTF-8?q?Remove=20stale=20note=20about=20kwargs=5F?=
 =?UTF-8?q?type=20removal=20=E2=80=94=20the=20feature=20is=20staying?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 src/diffusers/modular_pipelines/modular_pipeline_utils.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/diffusers/modular_pipelines/modular_pipeline_utils.py b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
index c2ffe2ac359f..3152eeb54fc4 100644
--- a/src/diffusers/modular_pipelines/modular_pipeline_utils.py
+++ b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
@@ -754,7 +754,6 @@ def wrap_text(text, indent, max_length):
     for param in params:
         # Format parameter name and type
         type_str = get_type_str(param.type_hint) if param.type_hint != Any else ""
-        # YiYi Notes: remove this line if we remove kwargs_type
         name = f"**{param.kwargs_type}" if param.name is None and param.kwargs_type is not None else param.name
         param_str = f"{param_indent}{name} (`{type_str}`"
 

From 13c90237639591e2755a1a3c8089efcd4cc1d092 Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sat, 18 Jul 2026 23:33:16 +0000
Subject: [PATCH 04/15] Clarify get_block_state default-resolution comment,
 drop getattr guards

defaults_by_block is a dataclass field so it always exists; the checks
are already inside the hasattr(param, "required") InputParam guard.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 src/diffusers/modular_pipelines/modular_pipeline.py       | 7 +++++--
 src/diffusers/modular_pipelines/modular_pipeline_utils.py | 4 ++--
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/diffusers/modular_pipelines/modular_pipeline.py b/src/diffusers/modular_pipelines/modular_pipeline.py
index f81d3233f7a7..00b51501210d 100644
--- a/src/diffusers/modular_pipelines/modular_pipeline.py
+++ b/src/diffusers/modular_pipelines/modular_pipeline.py
@@ -503,8 +503,11 @@ def get_block_state(self, state: PipelineState) -> dict:
             if input_param.name:
                 value = state.get(input_param.name)
                 if value is None:
-                    # a ConditionalPipelineBlocks parent merges disagreeing sub-block defaults to None at the
-                    # pipeline level (see combine_inputs); each block falls back to its own declared default here
+                    # if the value is None (not passed, or passed as None), the first block that reads it sets the
+                    # default at call time. For sequential blocks the default is already resolved at compile time
+                    # (first declaring block wins, see _get_inputs), but for conditional blocks the selected branch
+                    # is only known at runtime: disagreeing branch defaults merge to None (see combine_inputs) and
+                    # the block that actually runs applies its own declared default here
                     value = input_param.default
                 if input_param.required and value is None:
                     raise ValueError(f"Required input '{input_param.name}' is missing")
diff --git a/src/diffusers/modular_pipelines/modular_pipeline_utils.py b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
index 3152eeb54fc4..447a8ae94767 100644
--- a/src/diffusers/modular_pipelines/modular_pipeline_utils.py
+++ b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
@@ -761,7 +761,7 @@ def wrap_text(text, indent, max_length):
         if hasattr(param, "required"):
             if not param.required:
                 param_str += ", *optional*"
-                if getattr(param, "defaults_by_block", None):
+                if param.defaults_by_block is not None:
                     distinct_defaults = list(dict.fromkeys(param.defaults_by_block.values()))
                     param_str += (
                         f", defaults to {' or '.join(str(v) for v in distinct_defaults)}, depending on the workflow"
@@ -838,7 +838,7 @@ def get_type_str(type_hint):
 
         if hasattr(param, "required") and not param.required:
             param_str += ", *optional*"
-            if getattr(param, "defaults_by_block", None):
+            if param.defaults_by_block is not None:
                 distinct_defaults = list(dict.fromkeys(param.defaults_by_block.values()))
                 param_str += (
                     f", defaults to {' or '.join(f'`{v}`' for v in distinct_defaults)}, depending on the workflow"

From 8af5c6411f333dbef78892d2a7b7d9cd7fd1d727 Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sun, 19 Jul 2026 00:40:58 +0000
Subject: [PATCH 05/15] Add example comments to combine_inputs and formatters,
 revert description block restructure

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../modular_pipeline_utils.py                 | 24 +++++++++++++++----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/diffusers/modular_pipelines/modular_pipeline_utils.py b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
index 447a8ae94767..88d1d235f6e4 100644
--- a/src/diffusers/modular_pipelines/modular_pipeline_utils.py
+++ b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
@@ -762,6 +762,7 @@ def wrap_text(text, indent, max_length):
             if not param.required:
                 param_str += ", *optional*"
                 if param.defaults_by_block is not None:
+                    # e.g. ", defaults to None or 189, depending on the workflow"
                     distinct_defaults = list(dict.fromkeys(param.defaults_by_block.values()))
                     param_str += (
                         f", defaults to {' or '.join(str(v) for v in distinct_defaults)}, depending on the workflow"
@@ -771,10 +772,12 @@ def wrap_text(text, indent, max_length):
         param_str += "):"
 
         # Add description on a new line with additional indentation and wrapping
-        desc = param.description if param.description else "TODO: Add description."
-        desc = re.sub(r"\[(.*?)\]\((https?://[^\s\)]+)\)", r"[\1](\2)", desc)
-        wrapped_desc = wrap_text(desc, desc_indent, max_line_length)
-        param_str += f"\n{desc_indent}{wrapped_desc}"
+        if param.description:
+            desc = re.sub(r"\[(.*?)\]\((https?://[^\s\)]+)\)", r"[\1](\2)", param.description)
+            wrapped_desc = wrap_text(desc, desc_indent, max_line_length)
+            param_str += f"\n{desc_indent}{wrapped_desc}"
+        else:
+            param_str += f"\n{desc_indent}TODO: Add description."
 
         formatted_params.append(param_str)
 
@@ -839,6 +842,7 @@ def get_type_str(type_hint):
         if hasattr(param, "required") and not param.required:
             param_str += ", *optional*"
             if param.defaults_by_block is not None:
+                # e.g. ", defaults to `None` or `189`, depending on the workflow"
                 distinct_defaults = list(dict.fromkeys(param.defaults_by_block.values()))
                 param_str += (
                     f", defaults to {' or '.join(f'`{v}`' for v in distinct_defaults)}, depending on the workflow"
@@ -1117,6 +1121,15 @@ def combine_inputs(*named_input_lists: list[tuple[str, list[InputParam]]]) -> li
     are recorded in `defaults_by_block`; each block resolves its own default at runtime in `get_block_state`, and the
     docstring formatters render the per-block defaults.
 
+    Example:
+        combine_inputs(
+            ("img2img", [InputParam("prompt"), InputParam("strength", default=0.3)]),
+            ("inpaint", [InputParam("prompt"), InputParam("strength", default=0.9999)]),
+        )
+        returns:
+            InputParam("prompt")  # no disagreement -> first occurrence kept as-is
+            InputParam("strength", default=None, defaults_by_block={"img2img": 0.3, "inpaint": 0.9999})
+
     Args:
         named_input_lists: List of tuples containing (block_name, input_param_list) pairs
 
@@ -1134,7 +1147,8 @@ def combine_inputs(*named_input_lists: list[tuple[str, list[InputParam]]]) -> li
                 input_name = input_param.name
 
             if input_param.defaults_by_block:
-                # nested conditional block: prefix its block names with the sub-block name
+                # nested conditional block: prefix its block names with the sub-block name,
+                # e.g. {"img2img": 0.3, "inpaint": 0.9999} from sub-block "image" -> {"image.img2img": 0.3, "image.inpaint": 0.9999}
                 new_defaults = {f"{block_name}.{k}": v for k, v in input_param.defaults_by_block.items()}
             else:
                 new_defaults = {block_name: input_param.default}

From 1f32ed7d5731b1fdfb8cd8aca52b8971223ada09 Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sun, 19 Jul 2026 00:46:04 +0000
Subject: [PATCH 06/15] Comment the duplicate-input path in combine_inputs with
 the strength example

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 src/diffusers/modular_pipelines/modular_pipeline_utils.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/diffusers/modular_pipelines/modular_pipeline_utils.py b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
index 88d1d235f6e4..40a41561b900 100644
--- a/src/diffusers/modular_pipelines/modular_pipeline_utils.py
+++ b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
@@ -1158,9 +1158,13 @@ def combine_inputs(*named_input_lists: list[tuple[str, list[InputParam]]]) -> li
                 defaults_by_block[input_name] = new_defaults
                 continue
 
+            # duplicate input: accumulate this block's default,
+            # e.g. "strength" was {"img2img": 0.3}, after inpaint's turn it is {"img2img": 0.3, "inpaint": 0.9999}
             defaults_by_block[input_name].update(new_defaults)
             defaults = list(defaults_by_block[input_name].values())
             if any(d != defaults[0] for d in defaults[1:]):
+                # blocks disagree (0.3 vs 0.9999): combined default becomes None and the per-block defaults are
+                # recorded on the param; `replace` creates a fresh copy so the blocks' own params are never mutated
                 combined_dict[input_name] = replace(
                     combined_dict[input_name], default=None, defaults_by_block=dict(defaults_by_block[input_name])
                 )

From 7efee1110c5c2732fcf753136306074a6f3fa9e6 Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sun, 19 Jul 2026 01:01:15 +0000
Subject: [PATCH 07/15] Rework branch-defaults tests to reuse the image block
 fixtures

strength on img2img (0.3) / inpaint (0.9999), text2img as the None
sentinel branch; drop the separate video fixtures. Also add examples to
the combine_inputs accumulator comments.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../modular_pipeline_utils.py                 |   4 +-
 .../test_conditional_pipeline_blocks.py       | 184 ++++++------------
 2 files changed, 64 insertions(+), 124 deletions(-)

diff --git a/src/diffusers/modular_pipelines/modular_pipeline_utils.py b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
index 40a41561b900..4e501c26b4e0 100644
--- a/src/diffusers/modular_pipelines/modular_pipeline_utils.py
+++ b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
@@ -1136,8 +1136,8 @@ def combine_inputs(*named_input_lists: list[tuple[str, list[InputParam]]]) -> li
     Returns:
         List[InputParam]: Combined list of unique InputParam objects
     """
-    combined_dict = {}  # name -> InputParam
-    defaults_by_block = {}  # name -> {block_name: default}
+    combined_dict = {}  # name -> InputParam, e.g. {"strength": InputParam("strength", default=0.3)}
+    defaults_by_block = {}  # name -> {block_name: default}, e.g. {"strength": {"img2img": 0.3, "inpaint": 0.9999}}
 
     for block_name, inputs in named_input_lists:
         for input_param in inputs:
diff --git a/tests/modular_pipelines/test_conditional_pipeline_blocks.py b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
index 2ae173619933..2bde595add6c 100644
--- a/tests/modular_pipelines/test_conditional_pipeline_blocks.py
+++ b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
@@ -30,7 +30,8 @@ class TextToImageBlock(ModularPipelineBlocks):
 
     @property
     def inputs(self):
-        return [InputParam(name="prompt")]
+        # strength does not apply to text2img: None is a "user didn't pass this" sentinel
+        return [InputParam(name="prompt"), InputParam(name="strength", type_hint=float, default=None)]
 
     @property
     def intermediate_outputs(self):
@@ -42,6 +43,8 @@ def description(self):
 
     def __call__(self, components, state):
         block_state = self.get_block_state(state)
+        if block_state.strength is not None:
+            raise ValueError("`strength` is not supported for text2img.")
         block_state.workflow = "text2img"
         self.set_block_state(state, block_state)
         return components, state
@@ -52,11 +55,15 @@ class ImageToImageBlock(ModularPipelineBlocks):
 
     @property
     def inputs(self):
-        return [InputParam(name="prompt"), InputParam(name="image")]
+        return [
+            InputParam(name="prompt"),
+            InputParam(name="image"),
+            InputParam(name="strength", type_hint=float, default=0.3),
+        ]
 
     @property
     def intermediate_outputs(self):
-        return []
+        return [OutputParam(name="resolved_strength")]
 
     @property
     def description(self):
@@ -65,6 +72,7 @@ def description(self):
     def __call__(self, components, state):
         block_state = self.get_block_state(state)
         block_state.workflow = "img2img"
+        block_state.resolved_strength = block_state.strength
         self.set_block_state(state, block_state)
         return components, state
 
@@ -74,11 +82,16 @@ class InpaintBlock(ModularPipelineBlocks):
 
     @property
     def inputs(self):
-        return [InputParam(name="prompt"), InputParam(name="image"), InputParam(name="mask")]
+        return [
+            InputParam(name="prompt"),
+            InputParam(name="image"),
+            InputParam(name="mask"),
+            InputParam(name="strength", type_hint=float, default=0.9999),
+        ]
 
     @property
     def intermediate_outputs(self):
-        return []
+        return [OutputParam(name="resolved_strength")]
 
     @property
     def description(self):
@@ -87,6 +100,7 @@ def description(self):
     def __call__(self, components, state):
         block_state = self.get_block_state(state)
         block_state.workflow = "inpaint"
+        block_state.resolved_strength = block_state.strength
         self.set_block_state(state, block_state)
         return components, state
 
@@ -246,116 +260,27 @@ def test_description(self):
         assert "Conditional" in blocks.description
 
 
-class PlainVideoBlock(ModularPipelineBlocks):
-    model_name = "video"
-
-    @property
-    def inputs(self):
-        return [
-            InputParam(name="prompt"),
-            InputParam(name="num_frames", type_hint=int, default=189, description="Number of frames to generate."),
-        ]
-
-    @property
-    def intermediate_outputs(self):
-        return [OutputParam(name="resolved_num_frames")]
-
-    @property
-    def description(self):
-        return "plain video workflow: uses its declared num_frames default"
-
-    def __call__(self, components, state):
-        block_state = self.get_block_state(state)
-        block_state.resolved_num_frames = block_state.num_frames
-        self.set_block_state(state, block_state)
-        return components, state
-
-
-class ActionVideoBlock(ModularPipelineBlocks):
-    model_name = "video"
-
-    @property
-    def inputs(self):
-        return [
-            InputParam(name="prompt"),
-            InputParam(name="action"),
-            InputParam(name="num_frames", type_hint=int, default=None, description="Number of frames to generate."),
-        ]
-
-    @property
-    def intermediate_outputs(self):
-        return [OutputParam(name="resolved_num_frames")]
-
-    @property
-    def description(self):
-        return "action video workflow: num_frames must not be passed, it is derived from action"
-
-    def __call__(self, components, state):
-        block_state = self.get_block_state(state)
-        if block_state.num_frames is not None:
-            raise ValueError("`num_frames` has to be None if `action` is provided.")
-        block_state.resolved_num_frames = block_state.action + 1
-        self.set_block_state(state, block_state)
-        return components, state
-
-
-class SingleFrameBlock(ModularPipelineBlocks):
-    model_name = "video"
-
-    @property
-    def inputs(self):
-        return [
-            InputParam(name="prompt"),
-            InputParam(name="image"),
-            InputParam(name="num_frames", type_hint=int, default=1, description="Number of frames to generate."),
-        ]
-
-    @property
-    def intermediate_outputs(self):
-        return [OutputParam(name="resolved_num_frames")]
-
-    @property
-    def description(self):
-        return "single frame workflow"
-
-    def __call__(self, components, state):
-        block_state = self.get_block_state(state)
-        block_state.resolved_num_frames = block_state.num_frames
-        self.set_block_state(state, block_state)
-        return components, state
-
-
-class AutoVideoBlocks(AutoPipelineBlocks):
-    block_classes = [ActionVideoBlock, PlainVideoBlock]
-    block_names = ["action", "plain"]
-    block_trigger_inputs = ["action", None]
-
-    @property
-    def description(self):
-        return "Auto video blocks: runs the action workflow when `action` is provided, plain otherwise"
-
-
-class NestedVideoBlocks(ConditionalPipelineBlocks):
-    block_classes = [SingleFrameBlock, AutoVideoBlocks]
-    block_names = ["image", "video"]
-    block_trigger_inputs = ["image"]
-    default_block_name = "video"
+class NestedImageBlocks(ConditionalPipelineBlocks):
+    block_classes = [InpaintBlock, AutoImageBlocks]
+    block_names = ["refine", "image"]
+    block_trigger_inputs = ["mask"]
+    default_block_name = "image"
 
     @property
     def description(self):
-        return "Nested conditional blocks: single frame when `image` is provided, video otherwise"
+        return "Nested conditional blocks: refine when `mask` is provided, auto image blocks otherwise"
 
-    def select_block(self, image=None) -> str | None:
-        if image is not None:
-            return "image"
+    def select_block(self, mask=None) -> str | None:
+        if mask is not None:
+            return "refine"
         return None
 
 
 class TestConditionalBlocksBranchDefaults:
     def test_conflicting_defaults_merge_to_none(self):
-        merged = {p.name: p for p in AutoVideoBlocks().inputs}["num_frames"]
+        merged = {p.name: p for p in AutoImageBlocks().inputs}["strength"]
         assert merged.default is None
-        assert merged.defaults_by_block == {"action": None, "plain": 189}
+        assert merged.defaults_by_block == {"inpaint": 0.9999, "img2img": 0.3, "text2img": None}
 
     def test_agreeing_defaults_stay_untouched(self):
         combined = combine_inputs(
@@ -365,31 +290,46 @@ def test_agreeing_defaults_stay_untouched(self):
         assert combined[0].default == 5
         assert combined[0].defaults_by_block is None
 
-    def test_default_branch_resolves_own_default(self):
-        pipe = AutoVideoBlocks().init_pipeline()
-        state = pipe(prompt="p")
-        assert state.get("resolved_num_frames") == 189
+    def test_branch_resolves_own_default(self):
+        pipe = AutoImageBlocks().init_pipeline()
+        state = pipe(prompt="p", image="i")
+        assert state.get("resolved_strength") == 0.3
+
+        state = pipe(prompt="p", image="i", mask="m")
+        assert state.get("resolved_strength") == 0.9999
+
+    def test_explicit_value_overrides_branch_default(self):
+        pipe = AutoImageBlocks().init_pipeline()
+        state = pipe(prompt="p", image="i", strength=0.7)
+        assert state.get("resolved_strength") == 0.7
 
     def test_sentinel_branch_not_polluted_by_sibling_default(self):
-        pipe = AutoVideoBlocks().init_pipeline()
-        state = pipe(prompt="p", action=8)
-        assert state.get("resolved_num_frames") == 9
+        pipe = AutoImageBlocks().init_pipeline()
+        # text2img uses None as a "user didn't pass this" sentinel: without the per-block merge,
+        # img2img's 0.3 would leak into state and this call would raise
+        state = pipe(prompt="p")
+        assert state.get("resolved_strength") is None
 
     def test_sentinel_branch_rejects_explicit_value(self):
-        pipe = AutoVideoBlocks().init_pipeline()
-        with pytest.raises(ValueError, match="has to be None"):
-            pipe(prompt="p", action=8, num_frames=10)
+        pipe = AutoImageBlocks().init_pipeline()
+        with pytest.raises(ValueError, match="not supported for text2img"):
+            pipe(prompt="p", strength=0.5)
 
     def test_standalone_branch_keeps_default(self):
-        pipe = PlainVideoBlock().init_pipeline()
-        state = pipe(prompt="p")
-        assert state.get("resolved_num_frames") == 189
+        pipe = ImageToImageBlock().init_pipeline()
+        state = pipe(prompt="p", image="i")
+        assert state.get("resolved_strength") == 0.3
 
     def test_doc_renders_per_block_defaults(self):
-        doc = " ".join(AutoVideoBlocks().doc.split())
-        assert "num_frames (`int`, *optional*, defaults to None or 189, depending on the workflow):" in doc
+        doc = " ".join(AutoImageBlocks().doc.split())
+        assert "strength (`float`, *optional*, defaults to 0.9999 or 0.3 or None, depending on the workflow):" in doc
 
     def test_nested_defaults_prefixed_with_sub_block_name(self):
-        merged = {p.name: p for p in NestedVideoBlocks().inputs}["num_frames"]
+        merged = {p.name: p for p in NestedImageBlocks().inputs}["strength"]
         assert merged.default is None
-        assert merged.defaults_by_block == {"image": 1, "video.action": None, "video.plain": 189}
+        assert merged.defaults_by_block == {
+            "refine": 0.9999,
+            "image.inpaint": 0.9999,
+            "image.img2img": 0.3,
+            "image.text2img": None,
+        }

From 1c913ac08c7d27ba5b4d44896d66b43d52c4225f Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sun, 19 Jul 2026 01:52:00 +0000
Subject: [PATCH 08/15] Simplify branch-defaults tests: drop t2i sentinel and
 resolved_strength output

Assert on state.get("strength") directly (write-back records the branch's
resolved value); cover None-vs-non-None merge with a direct combine_inputs
test instead.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../test_conditional_pipeline_blocks.py       | 48 +++++++------------
 1 file changed, 18 insertions(+), 30 deletions(-)

diff --git a/tests/modular_pipelines/test_conditional_pipeline_blocks.py b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
index 2bde595add6c..ffa9d58c4a00 100644
--- a/tests/modular_pipelines/test_conditional_pipeline_blocks.py
+++ b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
@@ -13,14 +13,11 @@
 # limitations under the License.
 
 
-import pytest
-
 from diffusers.modular_pipelines import (
     AutoPipelineBlocks,
     ConditionalPipelineBlocks,
     InputParam,
     ModularPipelineBlocks,
-    OutputParam,
 )
 from diffusers.modular_pipelines.modular_pipeline_utils import combine_inputs
 
@@ -30,8 +27,7 @@ class TextToImageBlock(ModularPipelineBlocks):
 
     @property
     def inputs(self):
-        # strength does not apply to text2img: None is a "user didn't pass this" sentinel
-        return [InputParam(name="prompt"), InputParam(name="strength", type_hint=float, default=None)]
+        return [InputParam(name="prompt")]
 
     @property
     def intermediate_outputs(self):
@@ -43,8 +39,6 @@ def description(self):
 
     def __call__(self, components, state):
         block_state = self.get_block_state(state)
-        if block_state.strength is not None:
-            raise ValueError("`strength` is not supported for text2img.")
         block_state.workflow = "text2img"
         self.set_block_state(state, block_state)
         return components, state
@@ -63,7 +57,7 @@ def inputs(self):
 
     @property
     def intermediate_outputs(self):
-        return [OutputParam(name="resolved_strength")]
+        return []
 
     @property
     def description(self):
@@ -72,7 +66,6 @@ def description(self):
     def __call__(self, components, state):
         block_state = self.get_block_state(state)
         block_state.workflow = "img2img"
-        block_state.resolved_strength = block_state.strength
         self.set_block_state(state, block_state)
         return components, state
 
@@ -91,7 +84,7 @@ def inputs(self):
 
     @property
     def intermediate_outputs(self):
-        return [OutputParam(name="resolved_strength")]
+        return []
 
     @property
     def description(self):
@@ -100,7 +93,6 @@ def description(self):
     def __call__(self, components, state):
         block_state = self.get_block_state(state)
         block_state.workflow = "inpaint"
-        block_state.resolved_strength = block_state.strength
         self.set_block_state(state, block_state)
         return components, state
 
@@ -280,7 +272,7 @@ class TestConditionalBlocksBranchDefaults:
     def test_conflicting_defaults_merge_to_none(self):
         merged = {p.name: p for p in AutoImageBlocks().inputs}["strength"]
         assert merged.default is None
-        assert merged.defaults_by_block == {"inpaint": 0.9999, "img2img": 0.3, "text2img": None}
+        assert merged.defaults_by_block == {"inpaint": 0.9999, "img2img": 0.3}
 
     def test_agreeing_defaults_stay_untouched(self):
         combined = combine_inputs(
@@ -290,39 +282,36 @@ def test_agreeing_defaults_stay_untouched(self):
         assert combined[0].default == 5
         assert combined[0].defaults_by_block is None
 
+    def test_none_default_counts_as_disagreement(self):
+        # a None default is a sentinel ("user didn't pass this"), it must not be overridden by a sibling's default
+        combined = combine_inputs(
+            ("a", [InputParam(name="x", default=None)]),
+            ("b", [InputParam(name="x", default=5)]),
+        )
+        assert combined[0].default is None
+        assert combined[0].defaults_by_block == {"a": None, "b": 5}
+
     def test_branch_resolves_own_default(self):
         pipe = AutoImageBlocks().init_pipeline()
         state = pipe(prompt="p", image="i")
-        assert state.get("resolved_strength") == 0.3
+        assert state.get("strength") == 0.3
 
         state = pipe(prompt="p", image="i", mask="m")
-        assert state.get("resolved_strength") == 0.9999
+        assert state.get("strength") == 0.9999
 
     def test_explicit_value_overrides_branch_default(self):
         pipe = AutoImageBlocks().init_pipeline()
         state = pipe(prompt="p", image="i", strength=0.7)
-        assert state.get("resolved_strength") == 0.7
-
-    def test_sentinel_branch_not_polluted_by_sibling_default(self):
-        pipe = AutoImageBlocks().init_pipeline()
-        # text2img uses None as a "user didn't pass this" sentinel: without the per-block merge,
-        # img2img's 0.3 would leak into state and this call would raise
-        state = pipe(prompt="p")
-        assert state.get("resolved_strength") is None
-
-    def test_sentinel_branch_rejects_explicit_value(self):
-        pipe = AutoImageBlocks().init_pipeline()
-        with pytest.raises(ValueError, match="not supported for text2img"):
-            pipe(prompt="p", strength=0.5)
+        assert state.get("strength") == 0.7
 
     def test_standalone_branch_keeps_default(self):
         pipe = ImageToImageBlock().init_pipeline()
         state = pipe(prompt="p", image="i")
-        assert state.get("resolved_strength") == 0.3
+        assert state.get("strength") == 0.3
 
     def test_doc_renders_per_block_defaults(self):
         doc = " ".join(AutoImageBlocks().doc.split())
-        assert "strength (`float`, *optional*, defaults to 0.9999 or 0.3 or None, depending on the workflow):" in doc
+        assert "strength (`float`, *optional*, defaults to 0.9999 or 0.3, depending on the workflow):" in doc
 
     def test_nested_defaults_prefixed_with_sub_block_name(self):
         merged = {p.name: p for p in NestedImageBlocks().inputs}["strength"]
@@ -331,5 +320,4 @@ def test_nested_defaults_prefixed_with_sub_block_name(self):
             "refine": 0.9999,
             "image.inpaint": 0.9999,
             "image.img2img": 0.3,
-            "image.text2img": None,
         }

From c7cc16b5d9565f8c1f2abf4c34d93229c0b3095e Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sun, 19 Jul 2026 02:04:16 +0000
Subject: [PATCH 09/15] Move combine_inputs tests to module level as
 test_combine_inputs_*

block-a/block-b names, whole-list assertions, plus new coverage:
first-occurrence-wins, disagreement records every block, direct nested
prefixing.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../test_conditional_pipeline_blocks.py       | 71 ++++++++++++++-----
 1 file changed, 54 insertions(+), 17 deletions(-)

diff --git a/tests/modular_pipelines/test_conditional_pipeline_blocks.py b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
index ffa9d58c4a00..38c903df68db 100644
--- a/tests/modular_pipelines/test_conditional_pipeline_blocks.py
+++ b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
@@ -22,6 +22,60 @@
 from diffusers.modular_pipelines.modular_pipeline_utils import combine_inputs
 
 
+def test_combine_inputs_agreeing_defaults_stay_untouched():
+    combined = combine_inputs(
+        ("block-a", [InputParam(name="x", default=5)]),
+        ("block-b", [InputParam(name="x", default=5)]),
+    )
+    assert combined == [InputParam(name="x", default=5)]
+
+
+def test_combine_inputs_first_occurrence_wins():
+    combined = combine_inputs(
+        ("block-a", [InputParam(name="x", default=5, description="from block-a")]),
+        ("block-b", [InputParam(name="x", default=5, description="from block-b")]),
+    )
+    # duplicate inputs keep the first occurrence: block-b's description is dropped
+    assert combined == [InputParam(name="x", default=5, description="from block-a")]
+
+
+def test_combine_inputs_none_default_counts_as_disagreement():
+    # a None default is a sentinel ("user didn't pass this"), it must not be overridden by a sibling's default
+    combined = combine_inputs(
+        ("block-a", [InputParam(name="x", default=None)]),
+        ("block-b", [InputParam(name="x", default=5)]),
+    )
+    assert combined == [InputParam(name="x", default=None, defaults_by_block={"block-a": None, "block-b": 5})]
+
+
+def test_combine_inputs_disagreement_records_every_block():
+    combined = combine_inputs(
+        ("block-a", [InputParam(name="x", default=1)]),
+        ("block-b", [InputParam(name="x", default=2)]),
+        ("block-c", [InputParam(name="x", default=1)]),
+    )
+    # any disagreement records every block's default, including the ones that agree with each other
+    assert combined == [
+        InputParam(name="x", default=None, defaults_by_block={"block-a": 1, "block-b": 2, "block-c": 1})
+    ]
+
+
+def test_combine_inputs_nested_defaults_prefixed():
+    # block-b is itself a conditional block whose branches already disagree, so its param carries defaults_by_block;
+    # merging at the outer level prefixes those entries with the sub-block name
+    combined = combine_inputs(
+        ("block-a", [InputParam(name="x", default=3)]),
+        ("block-b", [InputParam(name="x", default=None, defaults_by_block={"branch-a": 1, "branch-b": 2})]),
+    )
+    assert combined == [
+        InputParam(
+            name="x",
+            default=None,
+            defaults_by_block={"block-a": 3, "block-b.branch-a": 1, "block-b.branch-b": 2},
+        )
+    ]
+
+
 class TextToImageBlock(ModularPipelineBlocks):
     model_name = "text2img"
 
@@ -274,23 +328,6 @@ def test_conflicting_defaults_merge_to_none(self):
         assert merged.default is None
         assert merged.defaults_by_block == {"inpaint": 0.9999, "img2img": 0.3}
 
-    def test_agreeing_defaults_stay_untouched(self):
-        combined = combine_inputs(
-            ("a", [InputParam(name="x", default=5)]),
-            ("b", [InputParam(name="x", default=5)]),
-        )
-        assert combined[0].default == 5
-        assert combined[0].defaults_by_block is None
-
-    def test_none_default_counts_as_disagreement(self):
-        # a None default is a sentinel ("user didn't pass this"), it must not be overridden by a sibling's default
-        combined = combine_inputs(
-            ("a", [InputParam(name="x", default=None)]),
-            ("b", [InputParam(name="x", default=5)]),
-        )
-        assert combined[0].default is None
-        assert combined[0].defaults_by_block == {"a": None, "b": 5}
-
     def test_branch_resolves_own_default(self):
         pipe = AutoImageBlocks().init_pipeline()
         state = pipe(prompt="p", image="i")

From 240ec8656cfb7e521a463ab7aed55d2083151353 Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sun, 19 Jul 2026 02:12:22 +0000
Subject: [PATCH 10/15] Tighten merge assertions: unique strength param + full
 InputParam equality

Also group combine_inputs tests under TestConditionalBlocksInputs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../test_conditional_pipeline_blocks.py       | 125 +++++++++---------
 1 file changed, 64 insertions(+), 61 deletions(-)

diff --git a/tests/modular_pipelines/test_conditional_pipeline_blocks.py b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
index 38c903df68db..077519d54ae7 100644
--- a/tests/modular_pipelines/test_conditional_pipeline_blocks.py
+++ b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
@@ -22,58 +22,55 @@
 from diffusers.modular_pipelines.modular_pipeline_utils import combine_inputs
 
 
-def test_combine_inputs_agreeing_defaults_stay_untouched():
-    combined = combine_inputs(
-        ("block-a", [InputParam(name="x", default=5)]),
-        ("block-b", [InputParam(name="x", default=5)]),
-    )
-    assert combined == [InputParam(name="x", default=5)]
-
-
-def test_combine_inputs_first_occurrence_wins():
-    combined = combine_inputs(
-        ("block-a", [InputParam(name="x", default=5, description="from block-a")]),
-        ("block-b", [InputParam(name="x", default=5, description="from block-b")]),
-    )
-    # duplicate inputs keep the first occurrence: block-b's description is dropped
-    assert combined == [InputParam(name="x", default=5, description="from block-a")]
-
-
-def test_combine_inputs_none_default_counts_as_disagreement():
-    # a None default is a sentinel ("user didn't pass this"), it must not be overridden by a sibling's default
-    combined = combine_inputs(
-        ("block-a", [InputParam(name="x", default=None)]),
-        ("block-b", [InputParam(name="x", default=5)]),
-    )
-    assert combined == [InputParam(name="x", default=None, defaults_by_block={"block-a": None, "block-b": 5})]
-
-
-def test_combine_inputs_disagreement_records_every_block():
-    combined = combine_inputs(
-        ("block-a", [InputParam(name="x", default=1)]),
-        ("block-b", [InputParam(name="x", default=2)]),
-        ("block-c", [InputParam(name="x", default=1)]),
-    )
-    # any disagreement records every block's default, including the ones that agree with each other
-    assert combined == [
-        InputParam(name="x", default=None, defaults_by_block={"block-a": 1, "block-b": 2, "block-c": 1})
-    ]
-
-
-def test_combine_inputs_nested_defaults_prefixed():
-    # block-b is itself a conditional block whose branches already disagree, so its param carries defaults_by_block;
-    # merging at the outer level prefixes those entries with the sub-block name
-    combined = combine_inputs(
-        ("block-a", [InputParam(name="x", default=3)]),
-        ("block-b", [InputParam(name="x", default=None, defaults_by_block={"branch-a": 1, "branch-b": 2})]),
-    )
-    assert combined == [
-        InputParam(
-            name="x",
-            default=None,
-            defaults_by_block={"block-a": 3, "block-b.branch-a": 1, "block-b.branch-b": 2},
+class TestConditionalBlocksInputs:
+    def test_combine_inputs_agreeing_defaults_stay_untouched(self):
+        combined = combine_inputs(
+            ("block-a", [InputParam(name="x", default=5)]),
+            ("block-b", [InputParam(name="x", default=5)]),
+        )
+        assert combined == [InputParam(name="x", default=5)]
+
+    def test_combine_inputs_first_occurrence_wins(self):
+        combined = combine_inputs(
+            ("block-a", [InputParam(name="x", default=5, description="from block-a")]),
+            ("block-b", [InputParam(name="x", default=5, description="from block-b")]),
+        )
+        # duplicate inputs keep the first occurrence: block-b's description is dropped
+        assert combined == [InputParam(name="x", default=5, description="from block-a")]
+
+    def test_combine_inputs_none_default_counts_as_disagreement(self):
+        # a None default is a sentinel ("user didn't pass this"), it must not be overridden by a sibling's default
+        combined = combine_inputs(
+            ("block-a", [InputParam(name="x", default=None)]),
+            ("block-b", [InputParam(name="x", default=5)]),
+        )
+        assert combined == [InputParam(name="x", default=None, defaults_by_block={"block-a": None, "block-b": 5})]
+
+    def test_combine_inputs_disagreement_records_every_block(self):
+        combined = combine_inputs(
+            ("block-a", [InputParam(name="x", default=1)]),
+            ("block-b", [InputParam(name="x", default=2)]),
+            ("block-c", [InputParam(name="x", default=1)]),
+        )
+        # any disagreement records every block's default, including the ones that agree with each other
+        assert combined == [
+            InputParam(name="x", default=None, defaults_by_block={"block-a": 1, "block-b": 2, "block-c": 1})
+        ]
+
+    def test_combine_inputs_nested_defaults_prefixed(self):
+        # block-b is itself a conditional block whose branches already disagree, so its param carries
+        # defaults_by_block; merging at the outer level prefixes those entries with the sub-block name
+        combined = combine_inputs(
+            ("block-a", [InputParam(name="x", default=3)]),
+            ("block-b", [InputParam(name="x", default=None, defaults_by_block={"branch-a": 1, "branch-b": 2})]),
         )
-    ]
+        assert combined == [
+            InputParam(
+                name="x",
+                default=None,
+                defaults_by_block={"block-a": 3, "block-b.branch-a": 1, "block-b.branch-b": 2},
+            )
+        ]
 
 
 class TextToImageBlock(ModularPipelineBlocks):
@@ -324,9 +321,14 @@ def select_block(self, mask=None) -> str | None:
 
 class TestConditionalBlocksBranchDefaults:
     def test_conflicting_defaults_merge_to_none(self):
-        merged = {p.name: p for p in AutoImageBlocks().inputs}["strength"]
-        assert merged.default is None
-        assert merged.defaults_by_block == {"inpaint": 0.9999, "img2img": 0.3}
+        strength_params = [p for p in AutoImageBlocks().inputs if p.name == "strength"]
+        assert len(strength_params) == 1
+        assert strength_params[0] == InputParam(
+            name="strength",
+            type_hint=float,
+            default=None,
+            defaults_by_block={"inpaint": 0.9999, "img2img": 0.3},
+        )
 
     def test_branch_resolves_own_default(self):
         pipe = AutoImageBlocks().init_pipeline()
@@ -351,10 +353,11 @@ def test_doc_renders_per_block_defaults(self):
         assert "strength (`float`, *optional*, defaults to 0.9999 or 0.3, depending on the workflow):" in doc
 
     def test_nested_defaults_prefixed_with_sub_block_name(self):
-        merged = {p.name: p for p in NestedImageBlocks().inputs}["strength"]
-        assert merged.default is None
-        assert merged.defaults_by_block == {
-            "refine": 0.9999,
-            "image.inpaint": 0.9999,
-            "image.img2img": 0.3,
-        }
+        strength_params = [p for p in NestedImageBlocks().inputs if p.name == "strength"]
+        assert len(strength_params) == 1
+        assert strength_params[0] == InputParam(
+            name="strength",
+            type_hint=float,
+            default=None,
+            defaults_by_block={"refine": 0.9999, "image.inpaint": 0.9999, "image.img2img": 0.3},
+        )

From 2c4a221c4a97617b6469de3db0e1da1f64ea7aba Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sun, 19 Jul 2026 02:19:06 +0000
Subject: [PATCH 11/15] Assert workflow in runtime tests, fold doc rendering
 into merge tests

workflow is now a declared intermediate output on the fixture blocks so
each runtime test shows which branch ran; the merge tests also assert
the rendered docstring (nested case covers distinct-value dedupe).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../test_conditional_pipeline_blocks.py       | 25 +++++++++++++------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/tests/modular_pipelines/test_conditional_pipeline_blocks.py b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
index 077519d54ae7..184f0bfd4535 100644
--- a/tests/modular_pipelines/test_conditional_pipeline_blocks.py
+++ b/tests/modular_pipelines/test_conditional_pipeline_blocks.py
@@ -18,6 +18,7 @@
     ConditionalPipelineBlocks,
     InputParam,
     ModularPipelineBlocks,
+    OutputParam,
 )
 from diffusers.modular_pipelines.modular_pipeline_utils import combine_inputs
 
@@ -82,7 +83,7 @@ def inputs(self):
 
     @property
     def intermediate_outputs(self):
-        return []
+        return [OutputParam(name="workflow")]
 
     @property
     def description(self):
@@ -108,7 +109,7 @@ def inputs(self):
 
     @property
     def intermediate_outputs(self):
-        return []
+        return [OutputParam(name="workflow")]
 
     @property
     def description(self):
@@ -135,7 +136,7 @@ def inputs(self):
 
     @property
     def intermediate_outputs(self):
-        return []
+        return [OutputParam(name="workflow")]
 
     @property
     def description(self):
@@ -321,6 +322,8 @@ def select_block(self, mask=None) -> str | None:
 
 class TestConditionalBlocksBranchDefaults:
     def test_conflicting_defaults_merge_to_none(self):
+        # inpaint (0.9999) and img2img (0.3) disagree on strength: the merged input's default becomes None
+        # and the per-block defaults are recorded in defaults_by_block
         strength_params = [p for p in AutoImageBlocks().inputs if p.name == "strength"]
         assert len(strength_params) == 1
         assert strength_params[0] == InputParam(
@@ -330,28 +333,32 @@ def test_conflicting_defaults_merge_to_none(self):
             defaults_by_block={"inpaint": 0.9999, "img2img": 0.3},
         )
 
+        # the docstring renders the distinct per-block defaults instead of a single value
+        doc = " ".join(AutoImageBlocks().doc.split())
+        assert "strength (`float`, *optional*, defaults to 0.9999 or 0.3, depending on the workflow):" in doc
+
     def test_branch_resolves_own_default(self):
         pipe = AutoImageBlocks().init_pipeline()
         state = pipe(prompt="p", image="i")
+        assert state.get("workflow") == "img2img"
         assert state.get("strength") == 0.3
 
         state = pipe(prompt="p", image="i", mask="m")
+        assert state.get("workflow") == "inpaint"
         assert state.get("strength") == 0.9999
 
     def test_explicit_value_overrides_branch_default(self):
         pipe = AutoImageBlocks().init_pipeline()
         state = pipe(prompt="p", image="i", strength=0.7)
+        assert state.get("workflow") == "img2img"
         assert state.get("strength") == 0.7
 
     def test_standalone_branch_keeps_default(self):
         pipe = ImageToImageBlock().init_pipeline()
         state = pipe(prompt="p", image="i")
+        assert state.get("workflow") == "img2img"
         assert state.get("strength") == 0.3
 
-    def test_doc_renders_per_block_defaults(self):
-        doc = " ".join(AutoImageBlocks().doc.split())
-        assert "strength (`float`, *optional*, defaults to 0.9999 or 0.3, depending on the workflow):" in doc
-
     def test_nested_defaults_prefixed_with_sub_block_name(self):
         strength_params = [p for p in NestedImageBlocks().inputs if p.name == "strength"]
         assert len(strength_params) == 1
@@ -361,3 +368,7 @@ def test_nested_defaults_prefixed_with_sub_block_name(self):
             default=None,
             defaults_by_block={"refine": 0.9999, "image.inpaint": 0.9999, "image.img2img": 0.3},
         )
+
+        # the docstring renders distinct values only: refine and image.inpaint both use 0.9999, shown once
+        doc = " ".join(NestedImageBlocks().doc.split())
+        assert "strength (`float`, *optional*, defaults to 0.9999 or 0.3, depending on the workflow):" in doc

From 324f660a01a135e1859f91e7ae2abb2dd74ff3de Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sun, 19 Jul 2026 02:23:21 +0000
Subject: [PATCH 12/15] docs: declare defaults in InputParam, not inside
 __call__

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .ai/modular.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.ai/modular.md b/.ai/modular.md
index 016b099b0c8b..823f7abcc06a 100644
--- a/.ai/modular.md
+++ b/.ai/modular.md
@@ -235,6 +235,8 @@ OutputParam(
 
 If a template's predefined description doesn't fit (e.g. the `"latents"` output template means "Denoised latents", which is wrong for the noisy latents out of a prepare-latents step) — drop the template and declare the field directly with an accurate description. See gotcha #5.
 
+**Declare defaults in the `InputParam`, not inside `__call__`.** A declared default is part of the block's contract, so the assembled pipeline is aware of it: the generated docstring shows it, `default_call_parameters` reports it, and when branches of a conditional blockset declare different defaults for the same input, the merged input records each branch's value (`defaults_by_block`) and every branch resolves its own default at runtime. Resolving a static default inside the block body instead (`if block_state.num_frames is None: block_state.num_frames = 189`) also works — nothing stops you — but the assembled pipeline is not aware of it: the input renders as `*optional*` with no default, and nothing at the pipeline level can report what the block will actually do. Resolve inside `__call__` only when the default is *computed* — derived from other inputs or component config (`height = components.default_sample_size * components.vae_scale_factor`) — since that genuinely can't be declared. And when several blocks in a sequence share an input, declare the same default on each (or only on the first block that reads it): in a sequence the input is one shared value, so disagreeing declarations are silently resolved first-block-wins.
+
 ## ComponentSpec patterns
 
 ```python

From 3483a8afd53789ae39901342eee9989393478c88 Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sun, 19 Jul 2026 02:31:09 +0000
Subject: [PATCH 13/15] docs: side-by-side default example in modular.md, test
 reference in combine_inputs

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .ai/modular.md                                      | 13 ++++++++++++-
 .../modular_pipelines/modular_pipeline_utils.py     |  3 +++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/.ai/modular.md b/.ai/modular.md
index 823f7abcc06a..b68129d08536 100644
--- a/.ai/modular.md
+++ b/.ai/modular.md
@@ -235,7 +235,18 @@ OutputParam(
 
 If a template's predefined description doesn't fit (e.g. the `"latents"` output template means "Denoised latents", which is wrong for the noisy latents out of a prepare-latents step) — drop the template and declare the field directly with an accurate description. See gotcha #5.
 
-**Declare defaults in the `InputParam`, not inside `__call__`.** A declared default is part of the block's contract, so the assembled pipeline is aware of it: the generated docstring shows it, `default_call_parameters` reports it, and when branches of a conditional blockset declare different defaults for the same input, the merged input records each branch's value (`defaults_by_block`) and every branch resolves its own default at runtime. Resolving a static default inside the block body instead (`if block_state.num_frames is None: block_state.num_frames = 189`) also works — nothing stops you — but the assembled pipeline is not aware of it: the input renders as `*optional*` with no default, and nothing at the pipeline level can report what the block will actually do. Resolve inside `__call__` only when the default is *computed* — derived from other inputs or component config (`height = components.default_sample_size * components.vae_scale_factor`) — since that genuinely can't be declared. And when several blocks in a sequence share an input, declare the same default on each (or only on the first block that reads it): in a sequence the input is one shared value, so disagreeing declarations are silently resolved first-block-wins.
+**Declare defaults in the `InputParam`, not inside `__call__`.**
+
+```python
+# yes
+InputParam(name="num_frames", type_hint=int, default=189)
+
+# no — works, but the assembled pipeline is not aware of it
+if block_state.num_frames is None:
+    block_state.num_frames = 189
+```
+
+A declared default is part of the block's contract, so the assembled pipeline is aware of it: the generated docstring shows it and `default_call_parameters` reports it. Resolved inside the body instead, the input renders as `*optional*` with no default, and nothing at the pipeline level can report what the block will actually do. Don't worry about branches of a conditional blockset declaring different defaults for the same input — each branch resolves its own at runtime. Resolve inside `__call__` only when the default is *computed* — derived from other inputs or component config (`height = components.default_sample_size * components.vae_scale_factor`). And when several blocks in a sequence share an input, declare the same default on each (or only on the first block that reads it): in a sequence the input is one shared value, so disagreeing declarations are silently resolved first-block-wins.
 
 ## ComponentSpec patterns
 
diff --git a/src/diffusers/modular_pipelines/modular_pipeline_utils.py b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
index 4e501c26b4e0..fe48d7f4a5e0 100644
--- a/src/diffusers/modular_pipelines/modular_pipeline_utils.py
+++ b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
@@ -1130,6 +1130,9 @@ def combine_inputs(*named_input_lists: list[tuple[str, list[InputParam]]]) -> li
             InputParam("prompt")  # no disagreement -> first occurrence kept as-is
             InputParam("strength", default=None, defaults_by_block={"img2img": 0.3, "inpaint": 0.9999})
 
+    See `TestConditionalBlocksInputs` in `tests/modular_pipelines/test_conditional_pipeline_blocks.py` for the full
+    behavior.
+
     Args:
         named_input_lists: List of tuples containing (block_name, input_param_list) pairs
 

From f8e3a35095b7613703573b7e91fb707210fc0843 Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sun, 19 Jul 2026 07:01:43 +0000
Subject: [PATCH 14/15] Fix doc-builder formatting; regenerate cosmos3
 use_system_prompt docstring

The combine_inputs docstring example is now a fenced code block so
doc-builder doesn't reflow it.

The cosmos3 use_system_prompt docstring change reflects a real behavior
fix this PR makes: the transfer/action branches declare default=True
while the standard text branch declares default=None as a sentinel that
falls back to the default_use_system_prompt config. Previously the
merged default True leaked into state before branch selection, so the
config fallback never fired for the standard workflow; each branch now
resolves its own default and the config is honored again.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../cosmos/modular_blocks_cosmos3.py          | 10 ++++----
 .../modular_pipeline_utils.py                 | 23 +++++++++++--------
 2 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3.py b/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3.py
index b62b6d7fe7b4..ed9bcd8f9346 100644
--- a/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3.py
+++ b/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3.py
@@ -140,9 +140,8 @@ class Cosmos3AutoTextEncoderStep(AutoPipelineBlocks):
               The text prompt that guides Cosmos3 generation.
           negative_prompt (`str`, *optional*):
               The negative text prompt used for classifier-free guidance.
-          use_system_prompt (`bool`, *optional*):
-              Whether to prepend the system prompt. Defaults to the pipeline configuration for standard and action
-              workflows and to True for transfer.
+          use_system_prompt (`bool`, *optional*, defaults to True or None, depending on the workflow):
+              Whether to prepend the Cosmos3 transfer system prompt.
           action (`CosmosActionCondition`, *optional*):
               Action-conditioning metadata and its reference visual input.
           fps (`float`, *optional*, defaults to 24.0):
@@ -1166,9 +1165,8 @@ class Cosmos3OmniBlocks(SequentialPipelineBlocks):
               The text prompt that guides Cosmos3 generation.
           negative_prompt (`str`, *optional*):
               The negative text prompt used for classifier-free guidance.
-          use_system_prompt (`bool`, *optional*):
-              Whether to prepend the system prompt. Defaults to the pipeline configuration for standard and action
-              workflows and to True for transfer.
+          use_system_prompt (`bool`, *optional*, defaults to True or None, depending on the workflow):
+              Whether to prepend the Cosmos3 transfer system prompt.
           action (`CosmosActionCondition`, *optional*):
               Action-conditioning metadata and its reference visual input.
           fps (`float`, *optional*, defaults to 24.0):
diff --git a/src/diffusers/modular_pipelines/modular_pipeline_utils.py b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
index fe48d7f4a5e0..2c859cc0ff96 100644
--- a/src/diffusers/modular_pipelines/modular_pipeline_utils.py
+++ b/src/diffusers/modular_pipelines/modular_pipeline_utils.py
@@ -1116,19 +1116,22 @@ def _accumulate(mapping: dict[str, Any]):
 
 def combine_inputs(*named_input_lists: list[tuple[str, list[InputParam]]]) -> list[InputParam]:
     """
-    Combines multiple lists of InputParam objects from different blocks. Duplicate inputs keep the first occurrence.
-    If duplicate inputs declare different defaults, the combined input's default is None and the per-block defaults
-    are recorded in `defaults_by_block`; each block resolves its own default at runtime in `get_block_state`, and the
+    Combines multiple lists of InputParam objects from different blocks. Duplicate inputs keep the first occurrence. If
+    duplicate inputs declare different defaults, the combined input's default is None and the per-block defaults are
+    recorded in `defaults_by_block`; each block resolves its own default at runtime in `get_block_state`, and the
     docstring formatters render the per-block defaults.
 
     Example:
-        combine_inputs(
-            ("img2img", [InputParam("prompt"), InputParam("strength", default=0.3)]),
-            ("inpaint", [InputParam("prompt"), InputParam("strength", default=0.9999)]),
-        )
-        returns:
-            InputParam("prompt")  # no disagreement -> first occurrence kept as-is
-            InputParam("strength", default=None, defaults_by_block={"img2img": 0.3, "inpaint": 0.9999})
+
+    ```python
+    combine_inputs(
+        ("img2img", [InputParam("prompt"), InputParam("strength", default=0.3)]),
+        ("inpaint", [InputParam("prompt"), InputParam("strength", default=0.9999)]),
+    )
+    # returns:
+    #   InputParam("prompt")  # no disagreement -> first occurrence kept as-is
+    #   InputParam("strength", default=None, defaults_by_block={"img2img": 0.3, "inpaint": 0.9999})
+    ```
 
     See `TestConditionalBlocksInputs` in `tests/modular_pipelines/test_conditional_pipeline_blocks.py` for the full
     behavior.

From 3a2888f1ba6d6e1dfa636459ada29596a4dbc880 Mon Sep 17 00:00:00 2001
From: yiyixuxu <yixu310@gmail.com>
Date: Sun, 19 Jul 2026 08:15:09 +0000
Subject: [PATCH 15/15] Regenerate cosmos3 auto docstrings

Mechanical output of utils/modular_auto_docstring.py for the cosmos
files this PR touches; regeneration of the remaining stale pipelines
moved to its own PR.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 .../cosmos/modular_blocks_cosmos3.py          | 22 +++++++++++++++++++
 .../modular_blocks_cosmos3_distilled.py       |  3 ++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3.py b/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3.py
index ed9bcd8f9346..d7c6c846fc8e 100644
--- a/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3.py
+++ b/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3.py
@@ -123,6 +123,9 @@ class Cosmos3AutoTextEncoderStep(AutoPipelineBlocks):
       Components:
           video_processor (`VideoProcessor`) text_tokenizer (`AutoTokenizer`)
 
+      Configs:
+          default_use_system_prompt (default: True) enable_safety_checker (default: True)
+
       Inputs:
           control_videos (`dict`, *optional*):
               Mapping of hint name (edge/blur/depth/seg/wsm) to the control video for that modality.
@@ -367,6 +370,9 @@ class Cosmos3VisionCoreDenoiseStep(SequentialPipelineBlocks):
       Components:
           transformer (`Cosmos3OmniTransformer`) scheduler (`UniPCMultistepScheduler`)
 
+      Configs:
+          use_native_flow_schedule (default: False)
+
       Inputs:
           cond_input_ids (`None`):
               Token IDs for the conditional prompt.
@@ -435,6 +441,9 @@ class Cosmos3VisionSoundCoreDenoiseStep(SequentialPipelineBlocks):
       Components:
           transformer (`Cosmos3OmniTransformer`) scheduler (`UniPCMultistepScheduler`)
 
+      Configs:
+          use_native_flow_schedule (default: False)
+
       Inputs:
           cond_input_ids (`None`):
               Token IDs for the conditional prompt.
@@ -516,6 +525,9 @@ class Cosmos3VisionActionCoreDenoiseStep(SequentialPipelineBlocks):
       Components:
           transformer (`Cosmos3OmniTransformer`) scheduler (`UniPCMultistepScheduler`)
 
+      Configs:
+          use_native_flow_schedule (default: False)
+
       Inputs:
           cond_input_ids (`None`):
               Token IDs for the conditional prompt.
@@ -601,6 +613,9 @@ class Cosmos3VisionSoundActionCoreDenoiseStep(SequentialPipelineBlocks):
       Components:
           transformer (`Cosmos3OmniTransformer`) scheduler (`UniPCMultistepScheduler`)
 
+      Configs:
+          use_native_flow_schedule (default: False)
+
       Inputs:
           cond_input_ids (`None`):
               Token IDs for the conditional prompt.
@@ -961,6 +976,9 @@ class Cosmos3AutoCoreDenoiseStep(ConditionalPipelineBlocks):
           transformer (`Cosmos3OmniTransformer`) vae (`AutoencoderKLWan`) video_processor (`VideoProcessor`) scheduler
           (`UniPCMultistepScheduler`)
 
+      Configs:
+          use_native_flow_schedule (default: False)
+
       Inputs:
           cond_input_ids (`None`):
               Token IDs for the conditional prompt.
@@ -1148,6 +1166,10 @@ class Cosmos3OmniBlocks(SequentialPipelineBlocks):
           (`Cosmos3OmniTransformer`) scheduler (`UniPCMultistepScheduler`) sound_tokenizer
           (`Cosmos3AVAEAudioTokenizer`)
 
+      Configs:
+          default_use_system_prompt (default: True) enable_safety_checker (default: True) use_native_flow_schedule
+          (default: False)
+
       Inputs:
           control_videos (`dict`, *optional*):
               Mapping of hint name (edge/blur/depth/seg/wsm) to the control video for that modality.
diff --git a/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3_distilled.py b/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3_distilled.py
index ff2be89f2241..e168cc24d8cd 100644
--- a/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3_distilled.py
+++ b/src/diffusers/modular_pipelines/cosmos/modular_blocks_cosmos3_distilled.py
@@ -165,7 +165,8 @@ class Cosmos3DistilledBlocks(SequentialPipelineBlocks):
           (`Cosmos3OmniTransformer`) scheduler (`FlowMatchEulerDiscreteScheduler`)
 
       Configs:
-          is_distilled (default: True) distilled_sigmas (default: None)
+          default_use_system_prompt (default: True) enable_safety_checker (default: True) is_distilled (default: True)
+          distilled_sigmas (default: None)
 
       Inputs:
           prompt (`str`):