plugins: surface plugin name and Python exception on init failure

"plugin failed to initialize" with no name and no exception text is
the canonical first-line indicator for a Python plugin that didn't
register — but it tells the user nothing about *which* plugin or
*why*. Encountered while diagnosing a flaky first-launch failure
where a Python plugin's init() silently returned False on cold
boot and succeeded on the next run, plus a Ready or Not instance
that wouldn't open.

Wrap the IPlugin::init trampoline in pyplugins.h manually instead
of relying on PYBIND11_OVERRIDE_PURE so we can:
  - log the plugin's name and the surrounding hint when init()
    returns False (typically a plugin swallowing an exception in
    its own try/except);
  - catch pybind11::error_already_set and log the Python exception
    text + traceback before returning False to the C++ caller.

plugincontainer.cpp's "plugin failed to initialize" line now also
prints the plugin name so the proxied-candidate context is clear.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2 files changed, 54 insertions, 2 deletions

diff --git a/libs/plugin_python/src/mobase/wrappers/pyplugins.h b/libs/plugin_python/src/mobase/wrappers/pyplugins.h
index ce9a911..1480690 100644
--- a/libs/plugin_python/src/mobase/wrappers/pyplugins.h
+++ b/libs/plugin_python/src/mobase/wrappers/pyplugins.h
@@ -16,6 +16,8 @@
 #include <uibase/ipluginpreview.h>
 #include <uibase/iplugintool.h>
 
+#include <log.h>
+
 // these needs to be defined in a header file for automoc - this file is included only
 // in pyplugins.cpp
 namespace mo2::python {
@@ -35,7 +37,50 @@ namespace mo2::python {
 
         bool init(IOrganizer* organizer) override
         {
-            PYBIND11_OVERRIDE_PURE(bool, PluginBase, init, organizer);
+            // Wrap the override manually so we can surface diagnostics when a
+            // Python plugin's init() silently returns False (the common case
+            // when a plugin's own try/except eats the exception) or raises
+            // an exception that would otherwise bubble up as a cryptic
+            // "plugin failed to initialize" in plugincontainer.
+            try {
+                pybind11::gil_scoped_acquire gil;
+                pybind11::function override_fn = pybind11::get_override(
+                    static_cast<const PluginBase*>(this), "init");
+                if (!override_fn) {
+                    pybind11::pybind11_fail(
+                        "Tried to call pure virtual function \"PluginBase::init\"");
+                }
+                pybind11::object result = override_fn(organizer);
+                const bool ok = pybind11::cast<bool>(result);
+                if (!ok) {
+                    QString pluginName;
+                    try {
+                        pluginName = this->name();
+                    } catch (...) {
+                    }
+                    MOBase::log::warn(
+                        "Python plugin init() returned False (plugin: '{}'). "
+                        "The plugin is probably swallowing an exception in "
+                        "its own try/except — check the plugin source for "
+                        "details.",
+                        pluginName.isEmpty() ? std::string("<unknown>")
+                                             : pluginName.toStdString());
+                }
+                return ok;
+            } catch (const pybind11::error_already_set& e) {
+                QString pluginName;
+                try {
+                    pluginName = this->name();
+                } catch (...) {
+                }
+                MOBase::log::error(
+                    "Python plugin init() raised an exception (plugin: '{}'): "
+                    "{}",
+                    pluginName.isEmpty() ? std::string("<unknown>")
+                                         : pluginName.toStdString(),
+                    e.what());
+                return false;
+            }
         }
         QString name() const override
         {
diff --git a/src/src/plugincontainer.cpp b/src/src/plugincontainer.cpp
index 99e8ddb..9aa15a2 100644
--- a/src/src/plugincontainer.cpp
+++ b/src/src/plugincontainer.cpp
@@ -485,7 +485,14 @@ bool PluginContainer::initPlugin(IPlugin* plugin, IPluginProxy* pluginProxy,
   }
 
   if (!plugin->init(proxy)) {
-    log::warn("plugin failed to initialize");
+    QString pluginName;
+    try {
+      pluginName = plugin->name();
+    } catch (...) {
+    }
+    log::warn("plugin failed to initialize: {}",
+              pluginName.isEmpty() ? std::string("<unnamed>")
+                                   : pluginName.toStdString());
     return false;
   }