diff --git a/README.md b/README.md
index 877639e..69ab5a8 100644
--- a/README.md
+++ b/README.md
@@ -44,6 +44,7 @@ References:
 
 ```bash
 uv sync --group dev --group detection
+uv run patch-mmdet-version-gate
 uv run pose-tracking-exp run_detection --config detection.toml camera0 camera1
 uv run pose-tracking-exp run_detection --source video --output-dir data/detections --config detection.toml cam0=/data/cam0.mp4 cam1=/data/cam1.mp4
 ```
@@ -58,6 +59,7 @@ The default backend is `yolo_rtmpose`, and the heavy runtime dependencies live i
 Checkpoint paths are explicit config fields; the code does not hardcode local checkpoint locations.
 The only inferred path is the MMPose config path, which is resolved relative to the installed `mmpose` package when `pose_config_path` is omitted.
 For offline video runs, the default sink is parquet and writes one `*_detected.parquet` file per source. `run_tracking` can consume that directory directly as replay input.
+`uv run patch-mmdet-version-gate` is an idempotent local-environment patch for the current `mmdet` compatibility assert against the rebuilt `mmcv` wheel. Re-run it after `uv sync` if the environment is recreated.
 
 Example `detection.toml`:
 
diff --git a/pyproject.toml b/pyproject.toml
index 09ccd3c..193be60 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -44,6 +44,7 @@ detection = [
 
 [project.scripts]
 pose-tracking-exp = "pose_tracking_exp.cli:main"
+patch-mmdet-version-gate = "pose_tracking_exp.detection.patch_mmdet:main"
 
 [tool.hatch.build.targets.wheel]
 packages = ["src/pose_tracking_exp"]
diff --git a/src/pose_tracking_exp/detection/__init__.py b/src/pose_tracking_exp/detection/__init__.py
index 0927a60..4d17de1 100644
--- a/src/pose_tracking_exp/detection/__init__.py
+++ b/src/pose_tracking_exp/detection/__init__.py
@@ -6,6 +6,11 @@ from pose_tracking_exp.detection.config import (
     resolve_instances,
 )
 from pose_tracking_exp.detection.factory import build_pose_shim
+from pose_tracking_exp.detection.patch_mmdet import (
+    patch_mmdet_init_file,
+    patch_mmdet_init_text,
+    resolve_mmdet_init_path,
+)
 from pose_tracking_exp.detection.runner import (
     SimpleMovingAverage,
     SourceSlot,
@@ -39,6 +44,9 @@ __all__ = [
     "ParquetPoseSink",
     "PoseBatchRequest",
     "PoseDetections",
+    "patch_mmdet_init_file",
+    "patch_mmdet_init_text",
+    "resolve_mmdet_init_path",
     "SimpleMovingAverage",
     "SourceFrame",
     "SourceSlot",
diff --git a/src/pose_tracking_exp/detection/patch_mmdet.py b/src/pose_tracking_exp/detection/patch_mmdet.py
new file mode 100644
index 0000000..61b98e6
--- /dev/null
+++ b/src/pose_tracking_exp/detection/patch_mmdet.py
@@ -0,0 +1,93 @@
+from __future__ import annotations
+
+import argparse
+import importlib.util
+from pathlib import Path
+import re
+import sys
+
+PATCH_SENTINEL = "Proceeding anyway because this environment intentionally uses the local build."
+
+MMCV_ASSERT_RE = re.compile(
+    r"assert\s*\(mmcv_version >= digit_version\(mmcv_minimum_version\)\s*"
+    r"and mmcv_version < digit_version\(mmcv_maximum_version\)\), \\\n"
+    r"\s*f'MMCV==\{mmcv\.__version__\} is used but incompatible\. ' \\\n"
+    r"\s*f'Please install mmcv>=\{mmcv_minimum_version\}, ' \\\n"
+    r"\s*f'<\{mmcv_maximum_version\}\.'",
+    re.MULTILINE,
+)
+
+WARN_IMPORT = "from warnings import warn\n"
+WARN_BLOCK = """if not (
+    mmcv_version >= digit_version(mmcv_minimum_version)
+    and mmcv_version < digit_version(mmcv_maximum_version)
+):
+    warn(
+        f'MMCV=={mmcv.__version__} is outside the tested mmdet range '
+        f'[{mmcv_minimum_version}, {mmcv_maximum_version}). '
+        'Proceeding anyway because this environment intentionally uses the local build.',
+        stacklevel=1,
+    )"""
+
+
+def patch_mmdet_init_text(source: str) -> tuple[str, bool]:
+    if PATCH_SENTINEL in source:
+        return source, False
+
+    if WARN_IMPORT not in source:
+        import_anchor = "from mmengine.utils import digit_version\n"
+        if import_anchor not in source:
+            raise RuntimeError("Could not find the mmengine digit_version import anchor in mmdet.__init__.")
+        source = source.replace(import_anchor, import_anchor + WARN_IMPORT, 1)
+
+    patched, count = MMCV_ASSERT_RE.subn(WARN_BLOCK, source, count=1)
+    if count != 1:
+        raise RuntimeError("Could not find the expected mmcv compatibility assert in mmdet.__init__.")
+    return patched, True
+
+
+def resolve_mmdet_init_path() -> Path:
+    spec = importlib.util.find_spec("mmdet")
+    if spec is None or spec.origin is None:
+        raise RuntimeError("Could not locate the installed `mmdet` package.")
+    path = Path(spec.origin)
+    if path.name != "__init__.py":
+        raise RuntimeError(f"Expected mmdet to resolve to __init__.py, got: {path}")
+    return path
+
+
+def patch_mmdet_init_file(path: Path) -> bool:
+    source = path.read_text(encoding="utf-8")
+    patched, changed = patch_mmdet_init_text(source)
+    if changed:
+        path.write_text(patched, encoding="utf-8")
+    return changed
+
+
+def build_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(
+        description="Patch the installed mmdet version gate to allow the local mmcv 2.2.0 build.",
+    )
+    parser.add_argument(
+        "--path",
+        type=Path,
+        default=None,
+        help="Optional explicit path to mmdet/__init__.py. Defaults to the installed package.",
+    )
+    return parser
+
+
+def main() -> int:
+    parser = build_parser()
+    args = parser.parse_args()
+    path = args.path if args.path is not None else resolve_mmdet_init_path()
+    changed = patch_mmdet_init_file(path)
+    if changed:
+        print(f"Patched mmdet version gate at {path}")
+    else:
+        print(f"mmdet version gate already patched at {path}")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/tests/test_patch_mmdet.py b/tests/test_patch_mmdet.py
new file mode 100644
index 0000000..c1e65a8
--- /dev/null
+++ b/tests/test_patch_mmdet.py
@@ -0,0 +1,56 @@
+from pathlib import Path
+
+from pose_tracking_exp.detection.patch_mmdet import PATCH_SENTINEL, patch_mmdet_init_file, patch_mmdet_init_text
+
+
+UNPATCHED_INIT = """# Copyright (c) OpenMMLab. All rights reserved.
+import mmcv
+import mmengine
+from mmengine.utils import digit_version
+
+from .version import __version__, version_info
+
+mmcv_minimum_version = '2.0.0rc4'
+mmcv_maximum_version = '2.2.0'
+mmcv_version = digit_version(mmcv.__version__)
+
+mmengine_minimum_version = '0.7.1'
+mmengine_maximum_version = '1.0.0'
+mmengine_version = digit_version(mmengine.__version__)
+
+assert (mmcv_version >= digit_version(mmcv_minimum_version)
+        and mmcv_version < digit_version(mmcv_maximum_version)), \\
+    f'MMCV=={mmcv.__version__} is used but incompatible. ' \\
+    f'Please install mmcv>={mmcv_minimum_version}, ' \\
+    f'<{mmcv_maximum_version}.'
+
+assert (mmengine_version >= digit_version(mmengine_minimum_version)
+        and mmengine_version < digit_version(mmengine_maximum_version)), \\
+    f'MMEngine=={mmengine.__version__} is used but incompatible. ' \\
+    f'Please install mmengine>={mmengine_minimum_version}, ' \\
+    f'<{mmengine_maximum_version}.'
+
+__all__ = ['__version__', 'version_info', 'digit_version']
+"""
+
+
+def test_patch_mmdet_init_text_rewrites_mmcv_assert() -> None:
+    patched, changed = patch_mmdet_init_text(UNPATCHED_INIT)
+
+    assert changed is True
+    assert PATCH_SENTINEL in patched
+    assert "from warnings import warn" in patched
+    assert "assert (mmengine_version >= digit_version(mmengine_minimum_version)" in patched
+
+
+def test_patch_mmdet_init_file_is_idempotent(tmp_path: Path) -> None:
+    init_path = tmp_path / "__init__.py"
+    init_path.write_text(UNPATCHED_INIT, encoding="utf-8")
+
+    assert patch_mmdet_init_file(init_path) is True
+    once = init_path.read_text(encoding="utf-8")
+    assert PATCH_SENTINEL in once
+
+    assert patch_mmdet_init_file(init_path) is False
+    twice = init_path.read_text(encoding="utf-8")
+    assert once == twice