diff --git a/nodes/__init__.py b/nodes/__init__.py
index 23a2be0..ff17a60 100644
--- a/nodes/__init__.py
+++ b/nodes/__init__.py
@@ -7,6 +7,7 @@ Nodes are thin interfaces; all compiler logic lives in the ``compiler`` package.
 
 from __future__ import annotations
 
+from .category_splitter_node import CategorySplitterNode
 from .resolver_node import ResolverNode
 from .scene_analyzer_node import SceneAnalyzerNode
 from .scene_validator_node import SceneValidatorNode
@@ -15,12 +16,14 @@ NODE_CLASS_MAPPINGS: dict[str, type] = {
     "SceneCompilerAnalyzer": SceneAnalyzerNode,
     "SceneCompilerValidator": SceneValidatorNode,
     "SceneCompilerResolver": ResolverNode,
+    "SceneCompilerCategorySplitter": CategorySplitterNode,
 }
 
 NODE_DISPLAY_NAME_MAPPINGS: dict[str, str] = {
     "SceneCompilerAnalyzer": "Scene Analyzer",
     "SceneCompilerValidator": "Scene Validator",
     "SceneCompilerResolver": "Resolver",
+    "SceneCompilerCategorySplitter": "Category Splitter",
 }
 
 __all__ = ["NODE_CLASS_MAPPINGS", "NODE_DISPLAY_NAME_MAPPINGS"]
diff --git a/nodes/category_splitter_node.py b/nodes/category_splitter_node.py
new file mode 100644
index 0000000..2e184a5
--- /dev/null
+++ b/nodes/category_splitter_node.py
@@ -0,0 +1,35 @@
+"""ComfyUI node for the Category Splitter (MASTER_SPEC §20).
+
+A thin interface: it adapts the Resolved Tags input to the Category Splitter
+module and surfaces the CompilerResult's data, warnings, and errors. No compiler
+logic; it never imports ComfyUI.
+
+The node outputs the Category Map (per-category grouping, in order); the
+per-category prompt strings are produced downstream by the Prompt Builder node
+(§19).
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+from compiler.splitter.category_splitter import split_into_categories
+
+from .adapters import format_messages
+
+
+class CategorySplitterNode:
+    """Groups Resolved Tags into a Category Map."""
+
+    CATEGORY = "Scene Compiler"
+    FUNCTION = "run"
+    RETURN_TYPES = ("CATEGORY_MAP", "STRING", "STRING")
+    RETURN_NAMES = ("category_map", "warnings", "errors")
+
+    @classmethod
+    def INPUT_TYPES(cls) -> dict[str, Any]:
+        return {"required": {"resolved_tags": ("RESOLVED_TAGS",)}}
+
+    def run(self, resolved_tags: Any) -> tuple[Any, str, str]:
+        result = split_into_categories(tuple(resolved_tags))
+        return (result.data, format_messages(result.warnings), format_messages(result.errors))
diff --git a/tests/test_category_splitter_node.py b/tests/test_category_splitter_node.py
new file mode 100644
index 0000000..5916268
--- /dev/null
+++ b/tests/test_category_splitter_node.py
@@ -0,0 +1,45 @@
+"""Tests for the Category Splitter ComfyUI node (issue #22)."""
+
+from __future__ import annotations
+
+import nodes
+import nodes.category_splitter_node as node_module
+from compiler.common.message_codes import message
+from compiler.common.result import CompilerResult
+from nodes.category_splitter_node import CategorySplitterNode
+from schemas.models import CategoryMap, ResolvedTag
+
+
+def rtag(name: str, category: str) -> ResolvedTag:
+    return ResolvedTag(tag=name, category=category, source_concept=name, knowledge_base_entry=name)
+
+
+def test_node_metadata() -> None:
+    assert CategorySplitterNode.RETURN_TYPES == ("CATEGORY_MAP", "STRING", "STRING")
+    assert CategorySplitterNode.RETURN_NAMES == ("category_map", "warnings", "errors")
+    assert "resolved_tags" in CategorySplitterNode.INPUT_TYPES()["required"]
+
+
+def test_splits_with_real_module() -> None:
+    tags = (rtag("1girl", "character"), rtag("long hair", "hair"))
+    category_map, warnings, errors = CategorySplitterNode().run(tags)
+    assert isinstance(category_map, CategoryMap)
+    assert [t.tag for t in category_map.tags_for("character")] == ["1girl"]
+    assert [t.tag for t in category_map.tags_for("hair")] == ["long hair"]
+    assert (warnings, errors) == ("", "")
+
+
+def test_delegates_and_surfaces_errors(monkeypatch) -> None:
+    monkeypatch.setattr(
+        node_module,
+        "split_into_categories",
+        lambda tags: CompilerResult().add_error(message("SC0008", "bad category")),
+    )
+    category_map, warnings, errors = CategorySplitterNode().run(())
+    assert category_map is None
+    assert "SC0008: bad category" in errors
+
+
+def test_registered_for_comfyui() -> None:
+    assert nodes.NODE_CLASS_MAPPINGS["SceneCompilerCategorySplitter"] is CategorySplitterNode
+    assert nodes.NODE_DISPLAY_NAME_MAPPINGS["SceneCompilerCategorySplitter"] == "Category Splitter"