diff --git a/tests/tools/test_dockerfile_pid1_reaping.py b/tests/tools/test_dockerfile_pid1_reaping.py
index 52532a78..8d5e38f2 100644
--- a/tests/tools/test_dockerfile_pid1_reaping.py
+++ b/tests/tools/test_dockerfile_pid1_reaping.py
@@ -106,8 +106,16 @@ def test_dockerfile_entrypoint_routes_through_the_init(dockerfile_text):
 
 
 def test_dockerfile_installs_tui_dependencies(dockerfile_text):
+    """The Dockerfile must install ui-tui's npm dependencies during build,
+    and must copy the workspace package tree (not just manifests) so npm
+    can resolve the @hermes/ink ``file:`` dep without falling back to the
+    bare manifest. See PR #16690 + a49f4c6 for the design.
+    """
     assert "ui-tui/package.json" in dockerfile_text
-    assert "ui-tui/packages/hermes-ink/package-lock.json" in dockerfile_text
+    # ui-tui/packages/hermes-ink/ is a `file:` workspace; copying the FULL
+    # tree (not just its manifests) is what lets npm resolve it correctly.
+    # Catches the regression where someone reverts to manifest-only copies.
+    assert "COPY ui-tui/packages/hermes-ink/ ui-tui/packages/hermes-ink/" in dockerfile_text
     assert any(
         "ui-tui" in step and "npm" in step and (" install" in step or " ci" in step)
         for step in _run_steps(dockerfile_text)
@@ -121,17 +129,24 @@ def test_dockerfile_builds_tui_assets(dockerfile_text):
     )
 
 
-def test_dockerfile_materializes_local_tui_ink_package(dockerfile_text):
-    assert any(
-        "ui-tui" in step
-        and "node_modules/@hermes/ink" in step
-        and "packages/hermes-ink" in step
-        and "rm -rf packages/hermes-ink/node_modules" in step
-        and "npm install --omit=dev" in step
-        and "--prefix node_modules/@hermes/ink" in step
-        and "rm -rf node_modules/@hermes/ink/node_modules/react" in step
-        and "await import('@hermes/ink')" in step
-        for step in _run_steps(dockerfile_text)
+def test_dockerfile_forces_npm_install_links_false_for_workspace_resolution(dockerfile_text):
+    """The Dockerfile must force npm to install ``file:`` deps as symlinks
+    rather than copies. Debian's bundled npm 9.x defaults to install-links=true
+    (deps installed as copies), which produces a hidden
+    node_modules/.package-lock.json that permanently disagrees with the root
+    lockfile (which is generated by npm 10+ using symlinks). The disagreement
+    trips the TUI launcher's _tui_need_npm_install() check on every startup
+    and triggers an EACCES-failing runtime `npm install`.
+
+    Replaces the older `--prefix node_modules/@hermes/ink` materialization
+    pattern (PR #16690) — that approach was retired in a49f4c6 in favor of
+    install-links=false because the materialization step was rebuilding TUI
+    assets unnecessarily.
+    """
+    assert "npm_config_install_links=false" in dockerfile_text, (
+        "ENV npm_config_install_links=false missing — without it, Debian npm 9.x "
+        "installs file: deps as copies, breaking @hermes/ink workspace resolution. "
+        "See PR #16690 + a49f4c6."
     )