diff --git a/tests/test_streamscope_deploy.py b/tests/test_streamscope_deploy.py
new file mode 100644
index 0000000..65bd7b0
--- /dev/null
+++ b/tests/test_streamscope_deploy.py
@@ -0,0 +1,37 @@
+import app
+
+
+def test_streamscope_deploy_replaces_legacy_container_before_compose(monkeypatch):
+    files = {path: "placeholder" for path in app.SPEEDTEST_REPO_FILES}
+    files["compose.yaml"] = """services:
+  streamscope:
+    build: .
+    ports:
+      - '127.0.0.1:8080:8080'
+    environment:
+      ADMIN_PASSWORD: "${ADMIN_PASSWORD:?required}"
+      SESSION_SECRET: "${SESSION_SECRET:?required}"
+    volumes:
+      - /app-config/speedtest/data:/data
+    cap_add:
+      - NET_RAW
+"""
+    files["Dockerfile"] = "FROM python:3.13-slim\nRUN apt-get install -y mtr-tiny\n"
+    commands = []
+
+    monkeypatch.setattr(app, "_remote_python", lambda script: (0, "", ""))
+
+    def fake_ssh(host, command, timeout=600):
+        commands.append(command)
+        return 0, "ok", ""
+
+    monkeypatch.setattr(app, "_ssh", fake_ssh)
+    result = app._deploy_speedtest_compose(
+        files,
+        "correct-horse-battery-staple",
+        "streamscope-session-secret-with-entropy",
+    )
+
+    deploy = next(command for command in commands if "compose up -d --remove-orphans" in command)
+    assert "docker rm -f speedtest" in deploy
+    assert result["application"] == "streamscope"