feat: stop lifecycle dispatch after slicing cancellation

src/libslic3r/GCode.cpp

@@ -2482,6 +2482,7 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
         ctx.name = std::to_string(print->model().id().id);
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = path;
+        ctx.cancellation_check = [print]() { return print->canceled(); };
         fire_lifecycle_event(LifecycleEvent::GCodeExportStarted, ctx);
     }
 
@@ -2533,6 +2534,7 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
             ctx.name = std::to_string(print->model().id().id);
             ctx.code = LifecycleEvtCode::Error;
             ctx.msg  = std::string(path) + "\n" + err_msg;
+            ctx.cancellation_check = [print]() { return print->canceled(); };
             fire_lifecycle_event(LifecycleEvent::GCodeExportFinished, ctx);
         }
         throw Slic3r::RuntimeError(err_msg);
@@ -2556,6 +2558,7 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
             ctx.name = std::to_string(print->model().id().id);
             ctx.code = LifecycleEvtCode::Error;
             ctx.msg  = std::string(path) + "\n" + ex.what();
+            ctx.cancellation_check = [print]() { return print->canceled(); };
             fire_lifecycle_event(LifecycleEvent::GCodeExportFinished, ctx);
         }
         throw;
@@ -2668,6 +2671,7 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
             ctx.name = std::to_string(print->model().id().id);
             ctx.code = LifecycleEvtCode::Error;
             ctx.msg  = std::string(path) + "\nFailed to rename the output G-code file: " + ret.message();
+            ctx.cancellation_check = [print]() { return print->canceled(); };
             fire_lifecycle_event(LifecycleEvent::GCodeExportFinished, ctx);
         }
         throw Slic3r::RuntimeError(
@@ -2686,6 +2690,7 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
         ctx.name = std::to_string(print->model().id().id);
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = path;
+        ctx.cancellation_check = [print]() { return print->canceled(); };
         fire_lifecycle_event(LifecycleEvent::GCodeExportFinished, ctx);
     }
 

src/libslic3r/LifecycleEvents.hpp

@@ -104,6 +104,11 @@ namespace Slic3r
 
         // Aggregate project dirty state for ProjectDirtyChanged.
         bool dirty = false;
+
+        // Optional host-side cancellation probe. Background slicing and G-code export events set
+        // this to the originating Print's cancellation state so dispatch can stop before calling
+        // the next capability. It is intentionally not exposed through the Python payload API.
+        std::function<bool()> cancellation_check;
     };
 
     inline std::string lifecycle_event_to_string(LifecycleEvent event)

src/libslic3r/Print.cpp

@@ -2699,6 +2699,7 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
         LifecycleEventContext ctx;
         ctx.name = std::to_string(m_model.id().id);
         ctx.code = LifecycleEvtCode::Ok;
+        ctx.cancellation_check = [this]() { return canceled(); };
         fire_lifecycle_event(LifecycleEvent::SliceStarted, ctx);
     }
 
@@ -3325,6 +3326,7 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
         LifecycleEventContext ctx;
         ctx.name = std::to_string(m_model.id().id);
         ctx.code = LifecycleEvtCode::Ok;
+        ctx.cancellation_check = [this]() { return canceled(); };
         fire_lifecycle_event(LifecycleEvent::SliceGeometryFinished, ctx);
     }
 }
@@ -4931,6 +4933,7 @@ void Print::export_gcode_from_previous_file(const std::string& file, GCodeProces
         ctx.name = std::to_string(m_model.id().id);
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = file;
+        ctx.cancellation_check = [this]() { return canceled(); };
         fire_lifecycle_event(LifecycleEvent::GCodeExportStarted, ctx);
     }
 
@@ -4960,6 +4963,7 @@ void Print::export_gcode_from_previous_file(const std::string& file, GCodeProces
             ctx.name = std::to_string(m_model.id().id);
             ctx.code = LifecycleEvtCode::Error;
             ctx.msg  = file + "\n" + ex.what();
+            ctx.cancellation_check = [this]() { return canceled(); };
             fire_lifecycle_event(LifecycleEvent::GCodeExportFinished, ctx);
         }
         throw Slic3r::RuntimeError(
@@ -4973,6 +4977,7 @@ void Print::export_gcode_from_previous_file(const std::string& file, GCodeProces
         ctx.name = std::to_string(m_model.id().id);
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = file;
+        ctx.cancellation_check = [this]() { return canceled(); };
         fire_lifecycle_event(LifecycleEvent::GCodeExportFinished, ctx);
     }
 }

src/slic3r/plugin/PluginManager.cpp

@@ -2092,8 +2092,17 @@ ExecutionResult PluginManager::run_script_capability(const std::string& plugin_k
 }
 
 void PluginManager::dispatch_lifecycle_event(LifecycleEvent evt, const LifecycleEventContext& ctx) {
+    const auto is_canceled = [&ctx]() {
+        return ctx.cancellation_check && ctx.cancellation_check();
+    };
+
+    if (is_canceled())
+        return;
+
     for (const auto& cap : get_plugin_capabilities()) {
         if (!cap || !cap->is_enabled()) continue;
+        if (is_canceled())
+            break;
         try {
             cap->on_lifecycle_event(evt, ctx);
         } catch (const std::exception& ex) {