Offer to pip install missing plugin dependencies instead of just warning

Builds on the previous branch's dependency check: the missing-deps
QMessageBox is now a Yes/No prompt. Yes runs a blocking
`sys.executable -m pip install <reqs>` (subprocess.run, output
captured), shows a result dialog, and on success proceeds straight to
enabling the plugin — no need to click Enable a second time.

Blocking is a deliberate simplification, not an oversight: this
codebase has no worker-thread/progress-dialog pattern for slow
operations anywhere else, so a threaded installer would be
inconsistent with everything else here. pip install is a one-time,
infrequent action, unlike e.g. a serial connect that runs constantly.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

1 files changed, 44 insertions, 7 deletions

diff --git a/ui/main_window.py b/ui/main_window.py
index 95cdb84..c04230c 100644
--- a/ui/main_window.py
+++ b/ui/main_window.py
@@ -299,20 +299,57 @@ class MainWindow(QMainWindow):
         missing = self._plugin_mgr.get_missing_dependencies(plugin_id)
         if missing:
             from PyQt6.QtWidgets import QMessageBox
-            QMessageBox.warning(
+            reply = QMessageBox.question(
                 self, "Missing Plugin Dependencies",
-                f"Can't enable this plugin — missing Python packages:\n\n"
+                f"This plugin needs packages that aren't installed:\n\n"
                 f"  {', '.join(missing)}\n\n"
-                f"Install with:\n  pip install {' '.join(missing)}"
+                f"Install them now with pip?",
+                QMessageBox.StandardButton.Yes | QMessageBox.StandardButton.No,
+                QMessageBox.StandardButton.No,
             )
+            if reply == QMessageBox.StandardButton.Yes:
+                if self._pip_install(missing):
+                    self._enable_plugin_now(plugin_id)
         else:
-            ctx = self._make_plugin_context()
-            plugin = self._plugin_mgr.enable(plugin_id, ctx)
-            if plugin:
-                self._install_plugin(plugin)
+            self._enable_plugin_now(plugin_id)
         if self._win_settings:
             self._win_settings.sync_plugin_button(plugin_id)
 
+    def _enable_plugin_now(self, plugin_id: str):
+        ctx = self._make_plugin_context()
+        plugin = self._plugin_mgr.enable(plugin_id, ctx)
+        if plugin:
+            self._install_plugin(plugin)
+
+    def _pip_install(self, requirements: list) -> bool:
+        """Blocking `pip install` of the given requirement strings.
+        Returns True on success; shows a result dialog either way."""
+        import subprocess
+        import sys
+        from PyQt6.QtWidgets import QMessageBox
+
+        QApplication.setOverrideCursor(Qt.CursorShape.WaitCursor)
+        try:
+            result = subprocess.run(
+                [sys.executable, "-m", "pip", "install", *requirements],
+                capture_output=True, text=True,
+            )
+        finally:
+            QApplication.restoreOverrideCursor()
+
+        if result.returncode == 0:
+            QMessageBox.information(
+                self, "Install Complete",
+                f"Installed: {', '.join(requirements)}"
+            )
+            return True
+        QMessageBox.critical(
+            self, "Install Failed",
+            f"pip install failed for: {', '.join(requirements)}\n\n"
+            f"{result.stderr.strip()[-1500:]}"
+        )
+        return False
+
     def plugin_disable(self, plugin_id: str):
         """Called by SettingsWindow when user disables a plugin."""
         self._uninstall_plugin(plugin_id)