Expose Cookbook user-install CLIs in Docker (#887)

Ensure pip --user console scripts like vLLM are visible to Docker
runtime and dependency probes by adding the user install bin directory
to PATH.

tests/test_shell_routes.py

@@ -3,6 +3,7 @@
 import builtins
 import importlib.util
 import json
+import os
 import sys
 from pathlib import Path
 from types import SimpleNamespace
@@ -14,7 +15,9 @@ from routes.shell_routes import (
     _running_in_container,
     _docker_row_status,
     _package_installed_from_probe,
+    _package_probe_script,
     _package_status_note,
+    _prepend_user_install_bins_to_path,
     _reject_cross_site,
     _ssh_base_argv,
     _venv_activate_prefix,
@@ -247,6 +250,26 @@ class TestPackageProbeStatus:
         assert _package_installed_from_probe("diffusers", missing_torch) is False
         assert _package_installed_from_probe("diffusers", ready) is True
 
+    def test_local_user_install_bin_is_added_to_path(self, monkeypatch, tmp_path):
+        user_base = tmp_path / "user-base"
+        monkeypatch.setattr("site.USER_BASE", str(user_base))
+        monkeypatch.setenv("HOME", str(tmp_path / "home"))
+        monkeypatch.setenv("PATH", "/usr/bin")
+
+        _prepend_user_install_bins_to_path()
+
+        parts = os.environ["PATH"].split(os.pathsep)
+        assert str(user_base / "bin") in parts
+        assert str(tmp_path / "home" / ".local" / "bin") in parts
+
+    def test_remote_package_probe_checks_user_install_bin(self):
+        script = _package_probe_script(["vllm"])
+
+        assert "site.USER_BASE" in script
+        assert "os.path.expanduser('~/.local/bin')" in script
+        assert "add_user_install_bins_to_path()" in script
+        assert "shutil.which(b)" in script
+
 
 class TestSshBaseArgv:
     def test_basic_host_no_port(self):