diff --git a/docker/Dockerfile.ci b/docker/Dockerfile.ci
index 4171b063e..84ce5aa41 100644
--- a/docker/Dockerfile.ci
+++ b/docker/Dockerfile.ci
@@ -10,7 +10,10 @@ ARG VLLM_BASE_TAG=v0.25.0
 # everything except the actual project dir, since that should not
 # change much across branches.
 FROM ${VLLM_BASE_IMAGE}:${VLLM_BASE_TAG} AS deps
-ARG APP_DIR=/workspace/vllm-omni
+# Keep APP_DIR outside /workspace so k8s Buildkite workspace mounts cannot
+# shadow the editable install target (#5364). Docker WORKDIR creates /opt if
+# needed.
+ARG APP_DIR=/opt/vllm-omni
 WORKDIR ${APP_DIR}
 
 RUN ln -sf /usr/bin/python3 /usr/bin/python
@@ -47,7 +50,7 @@ RUN uv pip install --system -e ".[dev]"
 # the heavy base image to build it. Editable install above already
 # registered APP_DIR, so we must not re-pip-install after COPY.
 FROM deps
-ARG APP_DIR=/workspace/vllm-omni
+ARG APP_DIR=/opt/vllm-omni
 WORKDIR ${APP_DIR}
 
 COPY --link . .
diff --git a/tests/buildkite/test_vllm_omni_package_discovery.py b/tests/buildkite/test_vllm_omni_package_discovery.py
new file mode 100644
index 000000000..118aedb15
--- /dev/null
+++ b/tests/buildkite/test_vllm_omni_package_discovery.py
@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""Guard package discovery outside repo-root ``sys.path[0]``.
+
+Covers the same failure class as:
+- ``vllm ... --omni`` (upstream ``find_spec("vllm_omni")``) — see #5364
+- ``python examples/.../end2end.py`` / multimodal client subprocesses, where
+  ``sys.path[0]`` is the script directory (not the repo root), so a cwd-only
+  layout can start OmniServer via ``python -m vllm_omni...`` and still fail
+  example scripts with ``ModuleNotFoundError: No module named 'vllm_omni'``.
+"""
+
+from __future__ import annotations
+
+import subprocess
+import sys
+from importlib.util import find_spec
+from pathlib import Path
+
+import pytest
+
+pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
+
+
+def _assert_subprocess_ok(proc: subprocess.CompletedProcess[str], *, detail: str) -> None:
+    assert proc.returncode == 0, f"{detail} (exit={proc.returncode})\nstdout:\n{proc.stdout}\nstderr:\n{proc.stderr}"
+
+
+def test_find_spec_vllm_omni() -> None:
+    """Same probe as upstream ``vllm`` CLI before delegating to omni_main."""
+    assert find_spec("vllm_omni") is not None
+    assert find_spec("vllm_omni.entrypoints.cli.main") is not None
+
+
+def test_find_spec_vllm_omni_from_non_repo_cwd(tmp_path: Path) -> None:
+    """Console-script / ``python -c`` style: discovery when cwd is not the repo root."""
+    code = (
+        "from importlib.util import find_spec; "
+        "assert find_spec('vllm_omni') is not None; "
+        "assert find_spec('vllm_omni.entrypoints.cli.main') is not None"
+    )
+    proc = subprocess.run(
+        [sys.executable, "-c", code],
+        cwd=tmp_path,
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+    _assert_subprocess_ok(proc, detail=f"find_spec failed from cwd={tmp_path}")
+
+
+def test_python_script_off_repo_root_sys_path(tmp_path: Path) -> None:
+    """``python path/to/script.py``: ``sys.path[0]`` is the script dir, not the repo root.
+
+    One case covers the end2end / online-client / orphan-dir layouts — they all
+    share this discovery constraint. Use ``find_spec`` only (no heavy imports)
+    so Simple Test stays fast.
+    """
+    script = tmp_path / "examples" / "offline_inference" / "hunyuan_image3" / "end2end_probe.py"
+    script.parent.mkdir(parents=True, exist_ok=True)
+    script.write_text(
+        "\n".join(
+            [
+                "from importlib.util import find_spec",
+                "import sys",
+                'print("initial_sys_path0", sys.path[0])',
+                'assert find_spec("vllm_omni") is not None, (sys.path[0], sys.path[:5])',
+                'assert find_spec("vllm_omni.entrypoints.cli.main") is not None',
+                'print("ok")',
+                "",
+            ]
+        ),
+        encoding="utf-8",
+    )
+    cwd = tmp_path / "run_cwd"
+    cwd.mkdir()
+    proc = subprocess.run(
+        [sys.executable, str(script)],
+        cwd=cwd,
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+    _assert_subprocess_ok(
+        proc,
+        detail=f"find_spec failed for python {script} with cwd={cwd}",
+    )
+    assert f"initial_sys_path0 {script.parent}" in proc.stdout