diff --git a/tests/test_docker_build.py b/tests/test_docker_build.py
new file mode 100644
index 00000000..bc788c74
--- /dev/null
+++ b/tests/test_docker_build.py
@@ -0,0 +1,89 @@
+# tests/test_docker_build.py
+import os
+import shutil
+import subprocess
+import time
+
+import pytest
+import requests
+
+
+IMAGE_NAME = "manual_slop:test"
+CONTAINER_NAME = "manual_slop_test_container"
+WEB_PORT = 18080
+HOOK_PORT = 18999
+
+
+@pytest.mark.docker
+def test_docker_image_builds(tmp_path):
+    """Build the Docker image. Slow; opt-in."""
+    if os.environ.get("RUN_DOCKER_TEST") != "1":
+        pytest.skip("Set RUN_DOCKER_TEST=1 to enable")
+    if not _docker_available():
+        pytest.skip("Docker not available in this environment")
+
+    repo_root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+    result = subprocess.run(
+        ["docker", "build", "-t", IMAGE_NAME, "."],
+        cwd=repo_root,
+        capture_output=True, text=True, timeout=600,
+    )
+    assert result.returncode == 0, f"Docker build failed: {result.stderr}"
+
+
+@pytest.mark.docker
+def test_docker_container_starts_and_responds():
+    """Run the container, verify web and hook endpoints respond."""
+    if os.environ.get("RUN_DOCKER_TEST") != "1":
+        pytest.skip("Set RUN_DOCKER_TEST=1 to enable")
+    if not _docker_available():
+        pytest.skip("Docker not available in this environment")
+
+    _cleanup_container()
+
+    repo_root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+    result = subprocess.run(
+        [
+            "docker", "run", "-d",
+            "--name", CONTAINER_NAME,
+            "-p", f"{WEB_PORT}:8080",
+            "-p", f"{HOOK_PORT}:8999",
+            IMAGE_NAME,
+        ],
+        cwd=repo_root,
+        capture_output=True, text=True, timeout=30,
+    )
+    assert result.returncode == 0, f"Docker run failed: {result.stderr}"
+
+    try:
+        start = time.time()
+        ready = False
+        while time.time() - start < 90:
+            try:
+                r = requests.get(f"http://127.0.0.1:{HOOK_PORT}/status", timeout=1)
+                if r.status_code == 200:
+                    ready = True
+                    break
+            except (requests.ConnectionError, requests.Timeout):
+                pass
+            time.sleep(1)
+        assert ready, "Container hook API did not respond within 90s"
+
+        r = requests.get(f"http://127.0.0.1:{WEB_PORT}/", timeout=5)
+        assert r.status_code == 200
+        body = r.content.lower()
+        assert b"<html" in body or b"<!doctype" in body, "Web endpoint did not return HTML"
+
+    finally:
+        _cleanup_container()
+
+
+def _docker_available() -> bool:
+    return shutil.which("docker") is not None
+
+
+def _cleanup_container() -> None:
+    subprocess.run(
+        ["docker", "rm", "-f", CONTAINER_NAME],
+        capture_output=True,
+    )
\ No newline at end of file