diff --git a/tests/unit/test_builtin_agent_images.py b/tests/unit/test_builtin_agent_images.py
index b08b3012..089df863 100644
--- a/tests/unit/test_builtin_agent_images.py
+++ b/tests/unit/test_builtin_agent_images.py
@@ -12,14 +12,19 @@ _AGENT_DOCKERFILES = tuple(sorted(_CONTRIB_DIR.glob("*/Dockerfile")))
 
 
 class TestBuiltinAgentImages(unittest.TestCase):
-    def test_all_use_debian_trixie_stable(self):
+    def test_all_share_one_digest_pinned_node_trixie_base(self):
         self.assertTrue(_AGENT_DOCKERFILES)
+        bases = []
         for dockerfile in _AGENT_DOCKERFILES:
             with self.subTest(provider=dockerfile.parent.name):
-                self.assertRegex(
+                match = re.search(
+                    r"(?m)^FROM "
+                    r"(node:22\.\d+\.\d+-trixie-slim@sha256:[0-9a-f]{64})\s*$",
                     dockerfile.read_text(),
-                    r"(?m)^FROM node:22-trixie-slim\s*$",
                 )
+                self.assertIsNotNone(match)
+                bases.append(match.group(1))
+        self.assertEqual(1, len(set(bases)))
 
     def test_none_install_podman(self):
         # podman lives in the nested-containers derived layer (nested_containers.py),
diff --git a/tests/unit/test_contrib_pi_provider.py b/tests/unit/test_contrib_pi_provider.py
index 5f3c0a1f..eb010217 100644
--- a/tests/unit/test_contrib_pi_provider.py
+++ b/tests/unit/test_contrib_pi_provider.py
@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import json
 import unittest
 from pathlib import Path
 from unittest.mock import MagicMock, patch
@@ -21,6 +22,7 @@ from bot_bottle.manifest import ManifestIndex
 
 _URL = "http://supervise:9100/"
 _PI_DOCKERFILE = Path(__file__).resolve().parents[2] / "bot_bottle/contrib/pi/Dockerfile"
+_PI_PACKAGE_JSON = _PI_DOCKERFILE.with_name("package.json")
 
 
 def _make_bottle(exec_result: ExecResult | None = None) -> MagicMock:
@@ -209,9 +211,13 @@ class TestPiSuperviseMcp(unittest.TestCase):
 
 
 class TestPiDockerfile(unittest.TestCase):
-    def test_installs_pi_cwd_at_build_time(self):
+    def test_installs_exact_pi_cwd_from_the_committed_lock(self):
         dockerfile = _PI_DOCKERFILE.read_text()
-        self.assertIn("pi install npm:@harms-haus/pi-cwd", dockerfile)
+        package = json.loads(_PI_PACKAGE_JSON.read_text())
+        version = package["dependencies"]["@harms-haus/pi-cwd"]
+        self.assertRegex(version, r"^\d+\.\d+\.\d+$")
+        self.assertIn("npm ci --omit=dev", dockerfile)
+        self.assertNotIn("pi install", dockerfile)
 
     def test_prepares_pi_extension_state_dirs_and_tmp_for_node(self):
         dockerfile = _PI_DOCKERFILE.read_text()