diff --git a/tests/plugins/host_agent/test_install_template.py b/tests/plugins/host_agent/test_install_template.py
new file mode 100644
index 0000000..07714df
--- /dev/null
+++ b/tests/plugins/host_agent/test_install_template.py
@@ -0,0 +1,75 @@
+"""Pure-function tests for install.sh.j2 rendering and agent.py parsing."""
+import subprocess
+from pathlib import Path
+
+import pytest
+from jinja2 import Environment, FileSystemLoader
+
+from plugins.host_agent.routes import _agent_version, AGENT_SOURCE_PATH
+
+
+TEMPLATE_DIR = Path(__file__).resolve().parents[3] / "plugins" / "host_agent" / "templates"
+
+
+def _render(**overrides) -> str:
+    env = Environment(loader=FileSystemLoader(str(TEMPLATE_DIR)))
+    defaults = dict(
+        url="https://r.example",
+        token="tok-abc",
+        agent_version="1.0.0",
+        host_name="testhost",
+        host_address="10.0.0.1",
+    )
+    defaults.update(overrides)
+    return env.get_template("install.sh.j2").render(**defaults)
+
+
+def test_render_contains_token_and_url():
+    out = _render()
+    assert "tok-abc" in out
+    assert "https://r.example" in out
+    assert "testhost" in out
+
+
+def test_render_contains_hardening_directives():
+    out = _render()
+    for needle in (
+        "NoNewPrivileges=yes",
+        "ProtectSystem=strict",
+        "ProtectHome=yes",
+        "PrivateTmp=yes",
+        "ReadOnlyPaths=/proc /sys",
+    ):
+        assert needle in out, f"missing {needle}"
+
+
+def test_render_has_uninstall_branch():
+    out = _render()
+    assert "--uninstall" in out
+    assert "systemctl disable --now roundtable-agent.service" in out
+
+
+def test_render_has_systemctl_enable():
+    out = _render()
+    assert "systemctl enable --now roundtable-agent.service" in out
+
+
+def test_render_uses_agent_py_url():
+    out = _render()
+    assert "/plugins/host_agent/agent.py" in out
+
+
+def test_rendered_script_passes_sh_n(tmp_path):
+    out = _render()
+    script = tmp_path / "install.sh"
+    script.write_text(out)
+    result = subprocess.run(
+        ["sh", "-n", str(script)], capture_output=True, text=True
+    )
+    assert result.returncode == 0, f"sh -n failed: {result.stderr}"
+
+
+def test_agent_version_parses_on_disk_agent():
+    assert AGENT_SOURCE_PATH.exists()
+    v = _agent_version()
+    assert v == "1.0.0"