tests: pin ink engine in _make_tui_argv npm-bootstrap tests (post-merge semantic fix)

Main's rewritten test_tui_npm_install.py tests call _make_tui_argv expecting
the Ink/npm flow unconditionally; with the dual-engine dispatch merged in,
_resolve_tui_engine() auto-selects opentui whenever ui-opentui/dist is built
in the repo, routing the call away from the path under test (first subprocess
became 'node --version' instead of 'npm run build'). Pin the engine to ink
via an autouse fixture, mirroring the existing pinning precedent in
test_tui_resume_flow.py.

tests/tools/test_local_shell_init.py

@@ -190,6 +190,49 @@ class TestSnapshotEndToEnd:
     """Spin up a real LocalEnvironment and confirm the snapshot sources
     extra init files."""
 
+    def test_exported_env_changes_persist_between_commands(self, tmp_path):
+        env = LocalEnvironment(cwd=str(tmp_path), timeout=15)
+        try:
+            first = env.execute(
+                'export HERMES_SESSION_ENV_PROBE="sticky"; '
+                'export PATH="/tmp/hermes-session-bin:$PATH"; '
+                'echo "first=$HERMES_SESSION_ENV_PROBE"'
+            )
+            second = env.execute(
+                'echo "second=$HERMES_SESSION_ENV_PROBE"; echo "PATH=$PATH"'
+            )
+        finally:
+            env.cleanup()
+
+        assert first["returncode"] == 0
+        assert second["returncode"] == 0
+        assert "first=sticky" in first.get("output", "")
+        output = second.get("output", "")
+        assert "second=sticky" in output
+        assert "/tmp/hermes-session-bin" in output
+
+    def test_venv_style_activation_persists_between_commands(self, tmp_path):
+        venv_bin = tmp_path / ".venv" / "bin"
+        venv_bin.mkdir(parents=True)
+        activate = venv_bin / "activate"
+        activate.write_text(
+            f'export VIRTUAL_ENV="{tmp_path / ".venv"}"\n'
+            f'export PATH="{venv_bin}:$PATH"\n'
+        )
+
+        env = LocalEnvironment(cwd=str(tmp_path), timeout=15)
+        try:
+            first = env.execute('source .venv/bin/activate; echo "venv=$VIRTUAL_ENV"')
+            second = env.execute('echo "venv=$VIRTUAL_ENV"; echo "PATH=$PATH"')
+        finally:
+            env.cleanup()
+
+        assert first["returncode"] == 0
+        assert second["returncode"] == 0
+        output = second.get("output", "")
+        assert f"venv={tmp_path / '.venv'}" in output
+        assert str(venv_bin) in output
+
     def test_snapshot_picks_up_init_file_exports(self, tmp_path, monkeypatch):
         init_file = tmp_path / "custom-init.sh"
         init_file.write_text(