diff --git a/conftest.py b/conftest.py
new file mode 100644
index 0000000..2d75b9d
--- /dev/null
+++ b/conftest.py
@@ -0,0 +1,171 @@
+"""
+Root-level pytest configuration for standalone testing outside ComfyUI.
+
+Installs ComfyUI stubs and a custom import hook so that the package's
+__init__.py (which pytest's Package.setup() always imports) loads cleanly
+without a live ComfyUI runtime.
+"""
+import sys
+import types
+import os
+import importlib
+import importlib.abc
+import importlib.machinery
+
+
+# Run immediately at conftest import time (before pytest_configure)
+_NODE_ROOT = os.path.dirname(os.path.abspath(__file__))
+_PKG_NAME = os.path.basename(_NODE_ROOT)  # "ComfyUI-Ultimate-Auto-Sampler-Config-Grid-Testing-Suite"
+
+
+def _install_stubs():
+    """Install all stubs needed to import the package __init__.py cleanly."""
+
+    # 1. External deps
+    for name in [
+        "torch", "torchvision", "torchaudio",
+        "folder_paths",
+        "comfy", "comfy.utils", "comfy.sd", "comfy.model_management",
+        "nodes", "aiohttp",
+    ]:
+        if name not in sys.modules:
+            sys.modules[name] = types.ModuleType(name)
+
+    # aiohttp.web
+    if "aiohttp.web" not in sys.modules:
+        web = types.ModuleType("aiohttp.web")
+        web.Response = type("Response", (), {"__init__": lambda s, *a, **kw: None})
+        web.json_response = lambda *a, **kw: None
+        web.RouteTableDef = type("RouteTableDef", (), {
+            "get": lambda s, *a, **kw: (lambda f: f),
+            "post": lambda s, *a, **kw: (lambda f: f),
+            "delete": lambda s, *a, **kw: (lambda f: f),
+            "put": lambda s, *a, **kw: (lambda f: f),
+        })
+        sys.modules["aiohttp.web"] = web
+        sys.modules["aiohttp"].web = web  # type: ignore[attr-defined]
+
+    # folder_paths.get_output_directory
+    fp = sys.modules["folder_paths"]
+    if not hasattr(fp, "get_output_directory"):
+        fp.get_output_directory = lambda: os.path.join(_NODE_ROOT, "_test_output")  # type: ignore
+
+    # server.PromptServer
+    if "server" not in sys.modules:
+        sys.modules["server"] = types.ModuleType("server")
+    srv = sys.modules["server"]
+    if not hasattr(srv, "PromptServer"):
+        _noop_deco = staticmethod(lambda *a, **kw: (lambda f: f))
+        _routes = type("_Routes", (), {
+            "get": _noop_deco, "post": _noop_deco,
+            "delete": _noop_deco, "put": _noop_deco,
+        })()
+        _ps_instance = type("_PS", (), {"routes": _routes})()
+        srv.PromptServer = type("PromptServer", (), {"instance": _ps_instance})  # type: ignore
+
+    # 2. Sub-module stubs (for relative imports in __init__.py)
+    _subs = {
+        "sampler_node": {"SamplerGridTester": type("SamplerGridTester", (), {})},
+        "dashboard_node": {"SamplerConfigDashboardViewer": type("SamplerConfigDashboardViewer", (), {})},
+        "html_generator": {"get_html_template": lambda *a, **kw: ""},
+        "config_builder_node": {"UltimateConfigBuilder": type("UltimateConfigBuilder", (), {})},
+        "json_text_node": {"SmartJSONTextNode": type("SmartJSONTextNode", (), {})},
+        "metadata_packer": {"pack_metadata_into_image": lambda *a, **kw: None},
+        "directory_scanner": {
+            "scan_directory_for_images": lambda *a, **kw: ([], {}),
+            "MEDIA_EXTENSIONS": set(),
+        },
+        "distribution_routes": {},
+        "upscale_runner": {
+            "start_upscale_job": lambda *a, **kw: (None, None),
+            "get_upscale_status": lambda *a, **kw: {},
+            "cancel_upscale_job": lambda *a, **kw: False,
+        },
+    }
+
+    for bare, attrs in _subs.items():
+        fq = f"{_PKG_NAME}.{bare}"
+        if bare not in sys.modules:
+            stub = types.ModuleType(bare)
+            sys.modules[bare] = stub
+        if fq not in sys.modules:
+            sys.modules[fq] = sys.modules[bare]
+        for k, v in attrs.items():
+            setattr(sys.modules[bare], k, v)
+            setattr(sys.modules[fq], k, v)
+
+    # 3. Pre-register the package itself
+    if _PKG_NAME not in sys.modules:
+        pkg_stub = types.ModuleType(_PKG_NAME)
+        pkg_stub.__path__ = [_NODE_ROOT]
+        pkg_stub.__package__ = _PKG_NAME
+        sys.modules[_PKG_NAME] = pkg_stub
+
+    # 4. Ensure node root is on sys.path
+    if _NODE_ROOT not in sys.path:
+        sys.path.insert(0, _NODE_ROOT)
+
+
+class _PackageInitLoader(importlib.abc.Loader):
+    """
+    Custom loader for the package __init__.py.
+    Sets __package__ correctly before executing the module so that relative
+    imports (from .sampler_node import X) resolve via sys.modules.
+    """
+
+    def __init__(self, path):
+        self._path = path
+
+    def create_module(self, spec):
+        return None  # use default semantics
+
+    def exec_module(self, module):
+        module.__file__ = self._path
+        module.__package__ = _PKG_NAME
+        module.__name__ = _PKG_NAME
+        module.__path__ = [_NODE_ROOT]  # makes relative imports resolve parent pkg
+        # Point sys.modules to this module object so relative imports find it
+        sys.modules[_PKG_NAME] = module
+        with open(self._path, "rb") as fh:
+            src = fh.read()
+        code = compile(src, self._path, "exec")
+        exec(code, module.__dict__)  # noqa: S102  – intentional dynamic exec for stub loading
+
+
+class _PackageInitFinder(importlib.abc.MetaPathFinder):
+    """
+    Intercepts any attempt to import the package __init__.py and routes it
+    through _PackageInitLoader so relative imports get the correct __package__.
+    """
+    _INIT_PATH = os.path.join(_NODE_ROOT, "__init__.py")
+
+    def find_spec(self, fullname, path, target=None):
+        # In importlib mode, pytest imports __init__.py as module name "__init__"
+        # (module_name_from_path returns "__init__" for package root __init__.py).
+        # We intercept that import and also the top-level package name import.
+        if fullname in ("__init__", _PKG_NAME):
+            if target is not None:
+                # target is the path pytest wants to load; check it's our __init__.py
+                try:
+                    if os.path.normcase(str(target.__spec__.origin)) != os.path.normcase(self._INIT_PATH):
+                        return None
+                except Exception:
+                    pass
+            spec = importlib.machinery.ModuleSpec(
+                fullname,
+                _PackageInitLoader(self._INIT_PATH),
+                origin=self._INIT_PATH,
+            )
+            spec.submodule_search_locations = [_NODE_ROOT]
+            return spec
+        return None
+
+
+# Install stubs + hook immediately so they're ready before pytest does anything
+_install_stubs()
+sys.meta_path.insert(0, _PackageInitFinder())
+
+
+def pytest_configure(config):
+    """Re-ensure stubs are in place after config initialises."""
+    _install_stubs()
diff --git a/ltx_video_generation.py b/ltx_video_generation.py
new file mode 100644
index 0000000..351e159
--- /dev/null
+++ b/ltx_video_generation.py
@@ -0,0 +1,70 @@
+"""
+LTX 2.3 Video Generation Module
+Two-stage SamplerCustomAdvanced pipeline with parallel audio rail.
+
+Pinned LTX node pack version: TBD — set during first smoke test.
+Required nodes (looked up via nodes.NODE_CLASS_MAPPINGS):
+- DiffusionModelLoaderKJ
+- DualCLIPLoader (built-in)
+- VAELoaderKJ
+- LatentUpscaleModelLoader
+- LTXVPreprocess, LTXVImgToVideoInplace, LTXVConditioning,
+- LTXVCropGuides, LTXVConcatAVLatent, LTXVSeparateAVLatent,
+- LTXVEmptyLatentAudio, LTXVAudioVAEDecode,
+- EmptyLTXVLatentVideo, LTXVLatentUpsampler,
+- ManualSigmas, KSamplerSelect, RandomNoise, CFGGuider,
+- SamplerCustomAdvanced, VAEDecodeTiled, CreateVideo, SaveVideo
+"""
+
+import os
+import sys
+import time
+import builtins
+import uuid
+from typing import List
+
+
+def safe_print(*args, **kwargs):
+    """Windows-safe print mirroring config_builder_node.safe_print."""
+    try:
+        builtins.print(*args, **kwargs)
+    except (OSError, ValueError):
+        try:
+            msg = " ".join(str(a) for a in args) + kwargs.get("end", "\n")
+            sys.__stdout__.write(msg)
+            sys.__stdout__.flush()
+        except Exception:
+            pass
+
+
+print = safe_print
+
+
+def parse_sigmas(sigma_str):
+    """Parse a comma-separated sigma string into a list of floats.
+
+    Args:
+        sigma_str: e.g. "0.85, 0.7250, 0.4219, 0.0"
+
+    Returns:
+        List of floats.
+
+    Raises:
+        ValueError: empty string, fewer than 2 values, or any token not a valid float.
+    """
+    if not sigma_str or not sigma_str.strip():
+        raise ValueError("Sigma string is empty")
+
+    tokens = [t.strip() for t in sigma_str.split(",") if t.strip()]
+    if len(tokens) < 2:
+        raise ValueError(
+            "Sigma string must contain at least 2 comma-separated values, got: " + repr(sigma_str)
+        )
+
+    result = []
+    for tok in tokens:
+        try:
+            result.append(float(tok))
+        except ValueError:
+            raise ValueError("Sigma token " + repr(tok) + " is not a valid float (in " + repr(sigma_str) + ")")
+    return result
diff --git a/pytest.ini b/pytest.ini
new file mode 100644
index 0000000..9b33eb7
--- /dev/null
+++ b/pytest.ini
@@ -0,0 +1,6 @@
+[pytest]
+testpaths = tests
+addopts = --import-mode=importlib
+pythonpath = .
+filterwarnings =
+    ignore::DeprecationWarning
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..040373d
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,46 @@
+"""
+Pytest configuration for standalone testing outside ComfyUI.
+
+The custom node's __init__.py requires ComfyUI internals (server, folder_paths,
+torch, etc.) that are not available in a plain Python environment.
+We stub those out here so pytest can collect and run unit tests without ComfyUI.
+"""
+import sys
+import types
+import os
+
+# ── Stub out ComfyUI-only modules before any test or __init__.py import ──────
+_COMFY_STUBS = [
+    "server",
+    "folder_paths",
+    "nodes",
+    "torch",
+    "aiohttp",
+    "aiohttp.web",
+    "comfy",
+    "comfy.utils",
+    "comfy.sd",
+    "comfy.model_management",
+]
+
+for _mod_name in _COMFY_STUBS:
+    if _mod_name not in sys.modules:
+        _stub = types.ModuleType(_mod_name)
+        # aiohttp.web needs a minimal RouteTableDef stub used by distribution_routes
+        if _mod_name == "aiohttp.web":
+            class _RouteTableDef:  # noqa: N801
+                def get(self, *a, **kw):
+                    return lambda fn: fn
+                def post(self, *a, **kw):
+                    return lambda fn: fn
+                def delete(self, *a, **kw):
+                    return lambda fn: fn
+                def put(self, *a, **kw):
+                    return lambda fn: fn
+            _stub.RouteTableDef = _RouteTableDef
+        sys.modules[_mod_name] = _stub
+
+# Ensure the custom node root is on sys.path so `ltx_video_generation` is importable
+_NODE_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+if _NODE_ROOT not in sys.path:
+    sys.path.insert(0, _NODE_ROOT)
diff --git a/tests/test_ltx_sigma_parser.py b/tests/test_ltx_sigma_parser.py
new file mode 100644
index 0000000..935e824
--- /dev/null
+++ b/tests/test_ltx_sigma_parser.py
@@ -0,0 +1,32 @@
+"""Tests for LTX sigma string parsing."""
+import pytest
+import sys
+import os
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from ltx_video_generation import parse_sigmas
+
+
+def test_parse_valid_sigmas():
+    result = parse_sigmas("1.0, 0.5, 0.0")
+    assert result == [1.0, 0.5, 0.0]
+
+
+def test_parse_strips_whitespace():
+    result = parse_sigmas("  0.85,  0.7250,0.4219, 0.0  ")
+    assert result == [0.85, 0.725, 0.4219, 0.0]
+
+
+def test_parse_single_value_raises():
+    with pytest.raises(ValueError, match="at least 2"):
+        parse_sigmas("1.0")
+
+
+def test_parse_empty_raises():
+    with pytest.raises(ValueError, match="empty"):
+        parse_sigmas("")
+
+
+def test_parse_malformed_raises():
+    with pytest.raises(ValueError, match="not a valid float"):
+        parse_sigmas("1.0, abc, 0.0")