diff --git a/src-tauri/installer.nsh b/src-tauri/installer.nsh
new file mode 100644
index 0000000..b02ce27
--- /dev/null
+++ b/src-tauri/installer.nsh
@@ -0,0 +1,44 @@
+; Tauri 2 NSIS installer hooks for the Windows ChaosEngineAI bundle.
+;
+; Tauri's default NSIS template installs the app under
+; %LOCALAPPDATA%\<identifier>\ and the uninstaller removes that tree on
+; uninstall. The GPU runtime bundle (torch + diffusers + transformers,
+; ~2.5 GB) is intentionally written to a sibling directory:
+;
+;     %LOCALAPPDATA%\ChaosEngineAI\extras\cp{major}{minor}\site-packages
+;
+; The path is namespaced by Python ABI tag (commit 24518af, v0.7.0-rc.5)
+; so a runtime upgrade that changes Python minor versions cannot shadow
+; the wheels from the previous tag.
+;
+; CRITICAL: this directory MUST survive an uninstall + reinstall cycle.
+; Re-downloading 2.5 GB of CUDA wheels every time the user upgrades the
+; desktop app is unacceptable, both for users on slow links and for the
+; PyPI mirrors that serve the bundle.
+;
+; The hooks below are intentionally empty as a guardrail. If anyone
+; later adds custom uninstall behaviour:
+;
+;   1. NEVER ``RMDir /r "$LOCALAPPDATA\ChaosEngineAI\extras"`` here.
+;   2. Test that ``setup.py:_extras_site_packages()`` resolves the same
+;      path before AND after a clean uninstall + reinstall on Windows.
+;   3. Mirror any change in ``src-tauri/src/lib.rs::chaosengine_extras_root``.
+
+!macro NSIS_HOOK_PREINSTALL
+  ; Reserved — currently a no-op. See contract above before adding code.
+!macroend
+
+!macro NSIS_HOOK_POSTINSTALL
+  ; Reserved — currently a no-op. See contract above before adding code.
+!macroend
+
+!macro NSIS_HOOK_PREUNINSTALL
+  ; Reserved — currently a no-op. See contract above before adding code.
+!macroend
+
+!macro NSIS_HOOK_POSTUNINSTALL
+  ; Reserved — currently a no-op. The persistent GPU runtime tree at
+  ; %LOCALAPPDATA%\ChaosEngineAI\extras MUST be left intact so an
+  ; immediate reinstall can pick it up without re-downloading 2.5 GB.
+  ; See contract above before adding code.
+!macroend
diff --git a/src-tauri/src/lib.rs b/src-tauri/src/lib.rs
index 4f29137..ddbe60b 100644
--- a/src-tauri/src/lib.rs
+++ b/src-tauri/src/lib.rs
@@ -697,6 +697,12 @@ fn apply_embedded_runtime_env(command: &mut Command, runtime: &EmbeddedRuntime)
 /// Returns ``None`` if we can't resolve a home directory at all (headless
 /// environments). Callers treat that as "no extras available".
 fn chaosengine_extras_root() -> Option<PathBuf> {
+    // The extras tree lives OUTSIDE the Tauri install directory so it
+    // survives uninstall + reinstall cycles — re-downloading the 2.5 GB
+    // GPU bundle on every desktop upgrade is unacceptable. The Windows
+    // NSIS installer is told to leave this path alone via the empty
+    // hooks in ``src-tauri/installer.nsh``; if anyone changes either
+    // side the other MUST be kept in sync.
     let base = if cfg!(windows) {
         env::var_os("LOCALAPPDATA")
             .map(PathBuf::from)
diff --git a/src-tauri/tauri.conf.json b/src-tauri/tauri.conf.json
index ea1faa0..c38d18f 100644
--- a/src-tauri/tauri.conf.json
+++ b/src-tauri/tauri.conf.json
@@ -52,6 +52,11 @@
       "hardenedRuntime": true,
       "entitlements": "macos/ChaosEngineAI.entitlements"
     },
+    "windows": {
+      "nsis": {
+        "installerHooks": "./installer.nsh"
+      }
+    },
     "resources": {
       "resources/": ""
     }
diff --git a/src/styles.css b/src/styles.css
index ec62ad7..d68b611 100644
--- a/src/styles.css
+++ b/src/styles.css
@@ -6269,6 +6269,15 @@ select.text-input {
   width: 100%;
   max-width: 100%;
   overflow: hidden;
+  /* Establishes a stacking context so the streaming pip output stays
+   * above the Prompt + Recent Outputs cards in Image Studio and Video
+   * Studio. Without these the panel renders behind those siblings on
+   * Windows during a long GPU bundle install — the log is still alive
+   * but the user can't see it. ``z-index: 5`` is enough to win against
+   * the surrounding ``.panel`` cards (which set no z-index of their
+   * own) without fighting the global tooltip portal (z-index: 1000+). */
+  position: relative;
+  z-index: 5;
 }
 .install-log-summary {
   cursor: pointer;
diff --git a/tests/test_extras_path.py b/tests/test_extras_path.py
new file mode 100644
index 0000000..aac78ab
--- /dev/null
+++ b/tests/test_extras_path.py
@@ -0,0 +1,63 @@
+"""Pin the persistent GPU extras path on Windows / Linux / macOS.
+
+The desktop installer is configured to leave this directory alone on
+uninstall (``src-tauri/installer.nsh`` on Windows; macOS uninstall is
+``rm /Applications/ChaosEngineAI.app`` which doesn't touch
+``~/Library/Application Support``). If the path computed by
+``_extras_site_packages`` ever drifts from what the installer hooks
+expect, the uninstall safety net breaks.
+
+The tests below pin both halves of the contract — the parent directory
+and the ABI tag layout — so any future move is loud.
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+import unittest
+from pathlib import Path
+from unittest import mock
+
+from backend_service.routes import setup as setup_routes
+
+
+class ExtrasSitePackagesTests(unittest.TestCase):
+    def setUp(self) -> None:
+        self._env_patcher = mock.patch.dict(os.environ, {}, clear=False)
+        self._env_patcher.start()
+        # Drop the override knob — the explicit env path is for tests
+        # that pin a custom location, not for the cross-OS shape check.
+        os.environ.pop("CHAOSENGINE_EXTRAS_SITE_PACKAGES", None)
+
+    def tearDown(self) -> None:
+        self._env_patcher.stop()
+
+    def test_path_includes_chaosengine_extras_namespace(self) -> None:
+        path = setup_routes._extras_site_packages()
+        self.assertIsNotNone(path)
+        assert path is not None  # type narrow
+        parts = path.parts
+        # 'ChaosEngineAI/extras/cp{maj}{min}/site-packages' suffix.
+        # The tree above (LOCALAPPDATA / Library/Application Support /
+        # XDG_DATA_HOME) is platform-specific; we only assert the tail.
+        self.assertEqual(parts[-4], "ChaosEngineAI")
+        self.assertEqual(parts[-3], "extras")
+        self.assertTrue(parts[-2].startswith("cp"))
+        self.assertEqual(parts[-1], "site-packages")
+
+    def test_python_abi_tag_matches_runtime(self) -> None:
+        path = setup_routes._extras_site_packages()
+        assert path is not None
+        expected_tag = f"cp{sys.version_info.major}{sys.version_info.minor}"
+        self.assertEqual(path.parts[-2], expected_tag)
+
+    def test_env_override_wins(self) -> None:
+        override = "/tmp/chaosengine-extras-override"
+        os.environ["CHAOSENGINE_EXTRAS_SITE_PACKAGES"] = override
+        path = setup_routes._extras_site_packages()
+        self.assertEqual(path, Path(override))
+
+
+if __name__ == "__main__":
+    unittest.main()