Load a CLI Project's Printer and Process Settings as the GUI Does

The CLI filled only the keys a project lacked from its system preset.
The GUI builds a project preset differently: the project's values go
over the default preset, without the print-host keys, and every key
the project does not list in different_settings_to_system is refreshed
to its base system preset's current value. After a profile update the
two sliced the same project differently.

That step now lives in Preset::load_external_config, which takes plain
configs and gets the base preset from a callback, so the collection
lookup stays in PresetCollection. PresetBundle::project_different_keys
builds the kept-key set from a project's escaped entry, adding the
preset bookkeeping keys, and is used by both the GUI and the CLI.
PresetCollection::load_external_preset calls the shared step with no
change in behaviour.

The CLI now builds the project's printer and process configs with the
same step, passing the system preset from resolve_system_preset. That
drops the hand-kept skip list for print-host and variant-layout keys
and the legacy-key check: the shared step already excludes print-host
keys and maps per-variant values onto the base preset's variant layout.
The --uptodate path and a printer or process given on the command line
are left as they were.

Because the GUI's kept-key set always holds the bookkeeping keys, the
refresh runs for every project that names a system preset, so the CLI
now loads that preset's vendor on every such run.

src/OrcaSlicer.cpp

@@ -2116,7 +2116,12 @@ int CLI::run(int argc, char **argv)
 
     // One resolver for the whole run, so presets from the same vendor tree share its load.
     std::unique_ptr<PresetBundle> system_preset_resolver;
-    auto resolve_preset = [&ensure_cli_preset_bundle, &system_preset_resolver](const std::string &file, DynamicPrintConfig &config,
+    auto ensure_system_preset_resolver = [&system_preset_resolver]() -> PresetBundle & {
+        if (!system_preset_resolver)
+            system_preset_resolver = std::make_unique<PresetBundle>();
+        return *system_preset_resolver;
+    };
+    auto resolve_preset = [&ensure_cli_preset_bundle, &ensure_system_preset_resolver](const std::string &file, DynamicPrintConfig &config,
                                                                                       std::string &config_type, const std::string &config_from,
                                                                                       bool probe_type, std::string &error) {
         const auto *inherits = config.option<ConfigOptionString>(BBL_JSON_KEY_INHERITS);
@@ -2126,9 +2131,7 @@ int CLI::run(int argc, char **argv)
         PresetBundle                 *bundle = nullptr;
         bool                          allow_source_manifest = false;
         if (config_from == "system") {
-            if (!system_preset_resolver)
-                system_preset_resolver = std::make_unique<PresetBundle>();
-            bundle                = system_preset_resolver.get();
+            bundle                = &ensure_system_preset_resolver();
             allow_source_manifest = true;
         } else {
             bundle = ensure_cli_preset_bundle(error);
@@ -3120,6 +3123,44 @@ int CLI::run(int argc, char **argv)
         return 0;
     };
 
+    // Load the project's printer and process settings as the GUI loads its presets: over the default preset,
+    // with every key the project does not list as changed, including keys saved before an option existed,
+    // taken from its current system preset.
+    auto load_project_preset = [this, &ensure_system_preset_resolver, &current_different_settings, filament_count](const std::string &system_name, Preset::Type type) {
+        if (system_name.empty())
+            return;
+        // Preset bookkeeping the CLI keeps in its own groups, e.g. inherits_group and print_compatible_printers.
+        static const std::set<std::string> bookkeeping_keys = {"inherits", "compatible_printers", "compatible_prints", "compatible_printers_condition",
+                                                               "compatible_prints_condition", "print_settings_id", "printer_settings_id"};
+        const size_t       index = type == Preset::TYPE_PRINTER ? filament_count + 1 : 0;
+        PresetBundle      &resolver = ensure_system_preset_resolver();
+        DynamicPrintConfig system_config;
+        t_config_option_keys keys;
+        const DynamicPrintConfig config = Preset::load_external_config(type,
+            type == Preset::TYPE_PRINTER ? resolver.printers.default_preset_for(m_print_config).config : resolver.prints.default_preset().config,
+            m_print_config, PresetBundle::project_different_keys(index < current_different_settings.size() ? current_different_settings[index] : std::string()),
+            [&](const std::string &) -> DynamicPrintConfig * {
+                std::string error;
+                if (resolver.resolve_system_preset(system_config, type, system_name, config_substitution_rule, error))
+                    return &system_config;
+                BOOST_LOG_TRIVIAL(warning) << boost::format("CLI: system preset '%1%' not resolved (%2%); the project keeps its values") % system_name % error;
+                return nullptr;
+            }, &keys);
+        for (const std::string &key : keys) {
+            const ConfigOption *opt = config.option(key);
+            const ConfigOption *old = m_print_config.option(key);
+            if (bookkeeping_keys.count(key) != 0 || opt == nullptr || (old != nullptr && *old == *opt))
+                continue;
+            BOOST_LOG_TRIVIAL(info) << boost::format("CLI: %1% from '%2%': %3% -> %4%") % key % system_name % (old ? old->serialize() : std::string("(missing)")) % opt->serialize();
+            m_print_config.set_key_value(key, opt->clone());
+        }
+    };
+    // The --uptodate path refreshes the project from its own system configs.
+    if (new_printer_name.empty() && load_machine_config.empty())
+        load_project_preset(current_printer_system_name, Preset::TYPE_PRINTER);
+    if (new_process_name.empty() && load_process_config.empty())
+        load_project_preset(current_process_system_name, Preset::TYPE_PRINT);
+
     std::vector<std::string>& different_settings = m_print_config.option<ConfigOptionStrings>("different_settings_to_system", true)->values;
     std::vector<std::string>& inherits_group = m_print_config.option<ConfigOptionStrings>("inherits_group", true)->values;
     inherits_group.resize(filament_count + 2, std::string());

src/libslic3r/Format/3mf.cpp

@@ -307,17 +307,14 @@ bool PrusaFileParser::check_3mf_from_prusa(const std::string filename)
 
             mz_zip_archive_file_stat stat;
             if (!mz_zip_reader_file_stat(&archive, model_file_index, &stat)) goto EXIT;
-            // expat sizes its buffer with an int, so a larger entry cannot be parsed in one piece.
-            if (stat.m_uncomp_size > static_cast<mz_uint64>(std::numeric_limits<int>::max())) goto EXIT;
 
-            const int xml_size = static_cast<int>(stat.m_uncomp_size);
-            void *parser_buffer = XML_GetBuffer(m_parser, xml_size);
+            void *parser_buffer = XML_GetBuffer(m_parser, (int) stat.m_uncomp_size);
             if (parser_buffer == nullptr) goto EXIT;
 
-            mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, static_cast<size_t>(xml_size), 0);
+            mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, (size_t) stat.m_uncomp_size, 0);
             if (res == 0) goto EXIT;
 
-            XML_ParseBuffer(m_parser, xml_size, 1);
+            XML_ParseBuffer(m_parser, (int) stat.m_uncomp_size, 1);
         }
     }
 
@@ -1349,26 +1346,19 @@ ModelVolumeType type_from_string(const std::string &s)
         XML_SetUserData(m_xml_parser, (void*)this);
         XML_SetElementHandler(m_xml_parser, _3MF_Importer::_handle_start_config_xml_element, _3MF_Importer::_handle_end_config_xml_element);
 
-        // expat sizes its buffer with an int, so a larger entry cannot be parsed in one piece.
-        if (stat.m_uncomp_size > static_cast<mz_uint64>(std::numeric_limits<int>::max())) {
-            add_error("Found invalid size");
-            return false;
-        }
-        const int xml_size = static_cast<int>(stat.m_uncomp_size);
-
-        void* parser_buffer = XML_GetBuffer(m_xml_parser, xml_size);
+        void* parser_buffer = XML_GetBuffer(m_xml_parser, (int)stat.m_uncomp_size);
         if (parser_buffer == nullptr) {
             add_error("Unable to create buffer");
             return false;
         }
 
-        mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, static_cast<size_t>(xml_size), 0);
+        mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, (size_t)stat.m_uncomp_size, 0);
         if (res == 0) {
             add_error("Error while reading config data to buffer");
             return false;
         }
 
-        if (!XML_ParseBuffer(m_xml_parser, xml_size, 1)) {
+        if (!XML_ParseBuffer(m_xml_parser, (int)stat.m_uncomp_size, 1)) {
             char error_buf[1024];
             ::sprintf(error_buf, "Error (%s) while parsing xml file at line %d", XML_ErrorString(XML_GetErrorCode(m_xml_parser)), (int)XML_GetCurrentLineNumber(m_xml_parser));
             add_error(error_buf);

src/libslic3r/Format/bbs_3mf.cpp

@@ -2508,26 +2508,19 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
         XML_SetEntityDeclHandler(m_xml_parser, nullptr);
         XML_SetExternalEntityRefHandler(m_xml_parser, nullptr);
 
-        // expat sizes its buffer with an int, so a larger entry cannot be parsed in one piece.
-        if (stat.m_uncomp_size > static_cast<mz_uint64>(std::numeric_limits<int>::max())) {
-            add_error("Found invalid size");
-            return false;
-        }
-        const int xml_size = static_cast<int>(stat.m_uncomp_size);
-
-        void* parser_buffer = XML_GetBuffer(m_xml_parser, xml_size);
+        void* parser_buffer = XML_GetBuffer(m_xml_parser, (int)stat.m_uncomp_size);
         if (parser_buffer == nullptr) {
             add_error("Unable to create buffer");
             return false;
         }
 
-        mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, static_cast<size_t>(xml_size), 0);
+        mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, (size_t)stat.m_uncomp_size, 0);
         if (res == 0) {
             add_error("Error while reading config data to buffer");
             return false;
         }
 
-        if (!XML_ParseBuffer(m_xml_parser, xml_size, 1)) {
+        if (!XML_ParseBuffer(m_xml_parser, (int)stat.m_uncomp_size, 1)) {
             char error_buf[1024];
             ::snprintf(error_buf, 1024, "Error (%s) while parsing xml file at line %d", XML_ErrorString(XML_GetErrorCode(m_xml_parser)), (int)XML_GetCurrentLineNumber(m_xml_parser));
             add_error(error_buf);

src/libslic3r/GCode.cpp

@@ -2504,7 +2504,8 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
 
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(print->model().id().id);
+        ctx.id = std::to_string(print->model().id().id);
+        ctx.name = print->get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = path;
         ctx.cancellation_check = [print]() { return print->canceled(); };
@@ -2556,7 +2557,8 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
         }
         {
             LifecycleEventContext ctx;
-            ctx.name = std::to_string(print->model().id().id);
+            ctx.id = std::to_string(print->model().id().id);
+            ctx.name = print->get_model_name();
             ctx.code = LifecycleEvtCode::Error;
             ctx.msg  = std::string(path) + "\n" + err_msg;
             ctx.cancellation_check = [print]() { return print->canceled(); };
@@ -2580,7 +2582,8 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
         boost::nowide::remove(path_tmp.c_str());
         {
             LifecycleEventContext ctx;
-            ctx.name = std::to_string(print->model().id().id);
+            ctx.id = std::to_string(print->model().id().id);
+            ctx.name = print->get_model_name();
             ctx.code = LifecycleEvtCode::Error;
             ctx.msg  = std::string(path) + "\n" + ex.what();
             ctx.cancellation_check = [print]() { return print->canceled(); };
@@ -2693,7 +2696,8 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
     if (ret) {
         {
             LifecycleEventContext ctx;
-            ctx.name = std::to_string(print->model().id().id);
+            ctx.id = std::to_string(print->model().id().id);
+            ctx.name = print->get_model_name();
             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(); };
@@ -2712,7 +2716,8 @@ void GCode::do_export(Print* print, const char* path, GCodeProcessorResult* resu
 
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(print->model().id().id);
+        ctx.id = std::to_string(print->model().id().id);
+        ctx.name = print->get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = path;
         ctx.cancellation_check = [print]() { return print->canceled(); };

src/libslic3r/Preset.cpp

@@ -974,6 +974,37 @@ void Preset::get_extruder_names_and_keysets(Type type, std::string& extruder_id_
     }
 }
 
+DynamicPrintConfig Preset::load_external_config(Type type, const DynamicPrintConfig &default_config, const DynamicPrintConfig &project_config,
+                                                const std::set<std::string> &different_settings_list,
+                                                const std::function<DynamicPrintConfig *(const std::string &inherits)> &find_base,
+                                                t_config_option_keys *keys)
+{
+    // Load the preset over a default preset, so that the missing fields are filled in from the default preset.
+    DynamicPrintConfig cfg(default_config);
+    // SoftFever: ignore print connection info from project
+    auto        cfg_keys = cfg.keys();
+    cfg_keys.erase(std::remove_if(cfg_keys.begin(), cfg_keys.end(),
+                              [](std::string &val) {
+                                return val == "print_host" || val == "print_host_webui" || val == "printhost_apikey" ||
+                                       val == "printhost_cafile" || val == "printhost_user" || val == "printhost_password" || val == "printhost_port";
+                              }),
+               cfg_keys.end());
+    cfg.apply_only(project_config, cfg_keys, true);
+
+    //add different settings check logic, replace the old system preset's default value with new system preset's default values
+    if (!different_settings_list.empty()) {
+        if (DynamicPrintConfig *base_config = find_base(Preset::inherits(cfg))) {
+            std::string extruder_id_name, extruder_variant_name;
+            std::set<std::string> *key_set1 = nullptr, *key_set2 = nullptr;
+            Preset::get_extruder_names_and_keysets(type, extruder_id_name, extruder_variant_name, &key_set1, &key_set2);
+            cfg.update_non_diff_values_to_base_config(*base_config, cfg_keys, different_settings_list, extruder_id_name, extruder_variant_name, *key_set1, *key_set2);
+        }
+    }
+    if (keys)
+        *keys = std::move(cfg_keys);
+    return cfg;
+}
+
 bool Preset::has_lidar(PresetBundle *preset_bundle)
 {
     bool has_lidar = false;
@@ -2596,20 +2627,6 @@ std::pair<Preset*, bool> PresetCollection::load_external_preset(
     const Semver                file_version,
     const std::string           filament_id)
 {
-    // Load the preset over a default preset, so that the missing fields are filled in from the default preset.
-    DynamicPrintConfig cfg(this->default_preset_for(combined_config).config);
-    // SoftFever: ignore print connection info from project
-    auto        keys = cfg.keys();
-    keys.erase(std::remove_if(keys.begin(), keys.end(),
-                              [](std::string &val) {
-                                return val == "print_host" || val == "print_host_webui" || val == "printhost_apikey" ||
-                                       val == "printhost_cafile" || val == "printhost_user" || val == "printhost_password" || val == "printhost_port";
-                              }),
-               keys.end());
-    cfg.apply_only(combined_config, keys, true);
-    std::string                 &inherits = Preset::inherits(cfg);
-
-    //add different settings check logic, replace the old system preset's default value with new system preset's default values
     std::deque<Preset>::iterator it       = this->find_preset_internal(original_name);
     bool                         found    = it != m_presets.end() && it->name == original_name;
     if (! found) {
@@ -2618,24 +2635,25 @@ std::pair<Preset*, bool> PresetCollection::load_external_preset(
         found = it != m_presets.end();
     }
 
-    std::string extruder_id_name, extruder_variant_name;
-    std::set<std::string> *key_set1 = nullptr, *key_set2 = nullptr;
-    Preset::get_extruder_names_and_keysets(m_type, extruder_id_name, extruder_variant_name, &key_set1, &key_set2);
-
-    if (!inherits.empty() && (different_settings_list.size() > 0)) {
+    t_config_option_keys keys;
+    DynamicPrintConfig cfg = Preset::load_external_config(m_type, this->default_preset_for(combined_config).config, combined_config, different_settings_list,
+        [this, &original_name, &path, found, it](const std::string &inherits) -> DynamicPrintConfig * {
+            if (!inherits.empty()) {
                 auto iter = this->find_preset_internal(inherits);
                 if (iter == m_presets.end() || iter->name != inherits)
                     iter = this->find_preset_renamed(inherits);
-        if (iter != m_presets.end()) {
-            //std::vector<std::string> dirty_options = cfg.diff(iter->config);
-            BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(": change preset %1% inherit %2% 's value to %3% 's values")%original_name %inherits %path;
-            cfg.update_non_diff_values_to_base_config(iter->config, keys, different_settings_list, extruder_id_name, extruder_variant_name, *key_set1, *key_set2);
+                if (iter == m_presets.end())
+                    return nullptr;
+                BOOST_LOG_TRIVIAL(info) << "load_external_preset" << boost::format(": change preset %1% inherit %2% 's value to %3% 's values")%original_name %inherits %path;
+                return &iter->config;
             }
+            if (found && it->is_system) {
+                BOOST_LOG_TRIVIAL(info) << "load_external_preset" << boost::format(": change preset %1% 's value to %2% 's values")%original_name %path;
+                return &it->config;
             }
-    else if (found && it->is_system && (different_settings_list.size() > 0)) {
-        BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(": change preset %1% 's value to %2% 's values")%original_name %path;
-        cfg.update_non_diff_values_to_base_config(it->config, keys, different_settings_list, extruder_id_name, extruder_variant_name, *key_set1, *key_set2);
-    }
+            return nullptr;
+        }, &keys);
+    std::string                 &inherits = Preset::inherits(cfg);
 
     //BBS: add config related logs
     BOOST_LOG_TRIVIAL(debug) << __FUNCTION__ << boost::format(" enter, type %1% , path %2%, name %3%, original_name %4%, inherits %5%")%Preset::get_type_string(m_type) %path %name %original_name %inherits;

src/libslic3r/Preset.hpp

@@ -403,6 +403,15 @@ public:
     std::string get_current_printer_type(PresetBundle *preset_bundle); // get current preset type
 
     static void get_extruder_names_and_keysets(Type type, std::string& extruder_id_name, std::string& extruder_variant_name, std::set<std::string>** p_key_set1, std::set<std::string>** p_key_set2);
+    // Config of a preset loaded from a project or config file: the project's values over the type's
+    // default preset config, without the print-host keys. When different_settings_list is not empty,
+    // every key not listed in it is then refreshed from the base system preset, which find_base returns
+    // for the project's "inherits" (nullptr when there is none), with the listed per-variant values
+    // mapped onto the base's extruder variants. keys, if given, receives the keys taken from the project.
+    static DynamicPrintConfig load_external_config(Type type, const DynamicPrintConfig &default_config, const DynamicPrintConfig &project_config,
+                                                   const std::set<std::string> &different_settings_list,
+                                                   const std::function<DynamicPrintConfig *(const std::string &inherits)> &find_base,
+                                                   t_config_option_keys *keys = nullptr);
     std::string get_printer_id() const { return vendor ? vendor->id : ""; }
 
     bool has_lidar(PresetBundle *preset_bundle);

src/libslic3r/PresetBundle.cpp

@@ -575,18 +575,20 @@ bool PresetBundle::resolve_preset_config(DynamicPrintConfig &config, Preset::Typ
 const PresetBundle *PresetBundle::load_source_vendor(const boost::filesystem::path &root_dir,
                                                     const std::string &vendor_id,
                                                     ForwardCompatibilitySubstitutionRule compatibility_rule,
-                                                    std::string &error)
+                                                    std::string &error, bool allow_cache)
 {
-    auto key = std::make_tuple(root_dir.string(), vendor_id, compatibility_rule);
+    auto key = std::make_tuple(root_dir.string(), vendor_id, compatibility_rule, allow_cache);
     if (auto it = m_source_vendor_bundles.find(key); it != m_source_vendor_bundles.end())
         return it->second.get();
 
     // The library loads with no base of its own, so the tree a vendor inherits from
     // is the same one that resolves the library's own presets.
+    const std::string   library_file = std::string(ORCA_FILAMENT_LIBRARY);
     const PresetBundle *library      = nullptr;
     if (vendor_id != ORCA_FILAMENT_LIBRARY &&
-        boost::filesystem::is_regular_file(root_dir / (std::string(ORCA_FILAMENT_LIBRARY) + ".json"))) {
-        library = load_source_vendor(root_dir, ORCA_FILAMENT_LIBRARY, compatibility_rule, error);
+        (boost::filesystem::is_regular_file(root_dir / (library_file + ".json")) ||
+         (allow_cache && boost::filesystem::is_regular_file(root_dir / (library_file + ".opc"))))) {
+        library = load_source_vendor(root_dir, ORCA_FILAMENT_LIBRARY, compatibility_rule, error, allow_cache);
         if (library == nullptr) {
             error = "OrcaFilamentLibrary contains invalid presets";
             return nullptr;
@@ -595,7 +597,7 @@ const PresetBundle *PresetBundle::load_source_vendor(const boost::filesystem::pa
 
     auto bundle = std::make_unique<PresetBundle>();
     bundle->m_preserve_vendor_source_paths = true;
-    bundle->load_vendor_configs_from_json(root_dir.string(), vendor_id, LoadSystem, compatibility_rule, library, false);
+    bundle->load_vendor_configs_from_json(root_dir.string(), vendor_id, LoadSystem, compatibility_rule, library, allow_cache);
     if (bundle->error_count() != 0) {
         error = "Vendor bundle contains invalid presets";
         return nullptr;
@@ -638,6 +640,43 @@ bool PresetBundle::resolve_preset_config_type(DynamicPrintConfig &config, Preset
     return true;
 }
 
+bool PresetBundle::resolve_system_preset(DynamicPrintConfig &config, Preset::Type type, const std::string &name,
+                                         ForwardCompatibilitySubstitutionRule compatibility_rule, std::string &error)
+{
+    const std::string vendor_id = find_preset_vendor(name, type);
+    if (vendor_id.empty()) {
+        error = "No vendor lists the preset";
+        return false;
+    }
+    // Release builds ship a vendor as its preset cache alone, without the profile JSONs.
+    auto installed = [&vendor_id](const fs::path &root) {
+        return fs::is_regular_file(root / (vendor_id + ".json")) || fs::is_regular_file(root / (vendor_id + ".opc"));
+    };
+    fs::path root_dir = fs::path(data_dir()) / PRESET_SYSTEM_DIR;
+    if (!installed(root_dir))
+        root_dir = fs::path(resources_dir()) / PRESET_PROFILES_DIR;
+    const bool cache_only = !fs::is_regular_file(root_dir / (vendor_id + ".json"));
+
+    try {
+        const PresetBundle *vendor = load_source_vendor(root_dir, vendor_id, compatibility_rule, error, cache_only);
+        if (vendor == nullptr)
+            return false;
+        const PresetCollection &collection = type == Preset::TYPE_PRINTER ? vendor->printers :
+                                             type == Preset::TYPE_PRINT   ? vendor->prints : vendor->filaments;
+        const Preset *preset = collection.find_preset(name, false);
+        if (preset == nullptr) {
+            error = "Preset was not found in its vendor bundle";
+            return false;
+        }
+        config = preset->config;
+    } catch (const std::exception &ex) {
+        error = ex.what();
+        return false;
+    }
+    error.clear();
+    return true;
+}
+
 PresetBundle::PresetBundle(const PresetBundle &rhs)
 {
     *this = rhs;
@@ -4574,6 +4613,15 @@ const std::set<std::string> ignore_settings_list ={
     "print_settings_id", "filament_settings_id", "printer_settings_id"
 };
 
+std::set<std::string> PresetBundle::project_different_keys(const std::string &different_settings)
+{
+    std::vector<std::string> keys;
+    Slic3r::unescape_strings_cstyle(different_settings, keys);
+    std::set<std::string> keys_set(keys.begin(), keys.end());
+    keys_set.insert(ignore_settings_list.begin(), ignore_settings_list.end());
+    return keys_set;
+}
+
 DynamicPrintConfig PresetBundle::full_fff_config(bool apply_extruder, std::optional<std::vector<int>> filament_maps_new, std::optional<std::vector<int>> filament_volume_maps_new) const
 {
     DynamicPrintConfig out;
@@ -5279,15 +5327,7 @@ void PresetBundle::load_config_file_config(const std::string &name_or_path, bool
         if (!is_published) {
             //BBS: add different settings logic
             BOOST_LOG_TRIVIAL(debug) << __FUNCTION__ << boost::format(": load print preset from print_settings_id");
-            std::vector<std::string> print_different_keys_vector;
-            std::string print_different_settings = different_values[0];
-            Slic3r::unescape_strings_cstyle(print_different_settings, print_different_keys_vector);
-            std::set<std::string> print_different_keys_set(print_different_keys_vector.begin(), print_different_keys_vector.end());
-            //if (!has_different_settings_to_system) {
-            //    print_different_keys_set.clear();
-            //}
-            //else
-                print_different_keys_set.insert(ignore_settings_list.begin(), ignore_settings_list.end());
+            std::set<std::string> print_different_keys_set = project_different_keys(different_values[0]);
             if (!print_compatible_printers.empty()) {
                 ConfigOptionStrings* compatible_printers = config.option<ConfigOptionStrings>("compatible_printers", true);
                 compatible_printers->values = print_compatible_printers;
@@ -5298,15 +5338,7 @@ void PresetBundle::load_config_file_config(const std::string &name_or_path, bool
             //clear compatible printers
             clear_compatible_printers(config);
 
-            std::vector<std::string> printer_different_keys_vector;
-            std::string printer_different_settings = different_values[num_filaments + 1];
-            Slic3r::unescape_strings_cstyle(printer_different_settings, printer_different_keys_vector);
-            std::set<std::string> printer_different_keys_set(printer_different_keys_vector.begin(), printer_different_keys_vector.end());
-            //if (!has_different_settings_to_system) {
-            //    printer_different_keys_set.clear();
-            //}
-            //else
-                printer_different_keys_set.insert(ignore_settings_list.begin(), ignore_settings_list.end());
+            std::set<std::string> printer_different_keys_set = project_different_keys(different_values[num_filaments + 1]);
             //BBS: add config related logs
             BOOST_LOG_TRIVIAL(debug) << __FUNCTION__ << boost::format(": load printer preset from printer_settings_id");
             load_preset(this->printers, num_filaments + 1, "printer_settings_id", printer_different_keys_set, std::string());
@@ -5325,15 +5357,7 @@ void PresetBundle::load_config_file_config(const std::string &name_or_path, bool
     			Preset                *loaded = nullptr;
 
                 //BBS: add different settings logic
-                std::vector<std::string> filament_different_keys_vector;
-                std::string filament_different_settings = different_values[1];
-                Slic3r::unescape_strings_cstyle(filament_different_settings, filament_different_keys_vector);
-                std::set<std::string> filament_different_keys_set(filament_different_keys_vector.begin(), filament_different_keys_vector.end());
-                //if (!has_different_settings_to_system) {
-                //    filament_different_keys_set.clear();
-                //}
-                //else
-                    filament_different_keys_set.insert(ignore_settings_list.begin(), ignore_settings_list.end());
+                std::set<std::string> filament_different_keys_set = project_different_keys(different_values[1]);
 
                 std::string filament_id = filament_ids[0];
                 //BBS: add config related logs
@@ -5396,15 +5420,7 @@ void PresetBundle::load_config_file_config(const std::string &name_or_path, bool
                     cfg.opt_string("inherits", true)                      = inherits_values[i + 1];
 
                     //BBS: add different settings logic
-                    std::vector<std::string> filament_different_keys_vector;
-                    std::string filament_different_settings = different_values[i+1];
-                    Slic3r::unescape_strings_cstyle(filament_different_settings, filament_different_keys_vector);
-                    std::set<std::string> filament_different_keys_set(filament_different_keys_vector.begin(), filament_different_keys_vector.end());
-                    //if (!has_different_settings_to_system) {
-                    //    filament_different_keys_set.clear();
-                    //}
-                    //else
-                        filament_different_keys_set.insert(ignore_settings_list.begin(), ignore_settings_list.end());
+                    std::set<std::string> filament_different_keys_set = project_different_keys(different_values[i+1]);
 
                     std::string filament_id = filament_ids[i];
 

src/libslic3r/PresetBundle.hpp

@@ -234,6 +234,9 @@ public:
 
     // ORCA: utility function to find the vendor for a given preset name
     static std::string find_preset_vendor(const std::string& preset_name, Preset::Type type);
+    // Keys a project keeps when its presets are loaded: those listed in its escaped
+    // "different_settings_to_system" entry for the preset, plus the preset bookkeeping keys.
+    static std::set<std::string> project_different_keys(const std::string &different_settings);
 
     PresetBundle();
     PresetBundle(const PresetBundle &rhs);
@@ -273,6 +276,10 @@ public:
                                     const std::string &source_file,
                                     ForwardCompatibilitySubstitutionRule compatibility_rule,
                                     std::string &error, bool allow_source_manifest = true);
+    // Resolve a system preset by name. The vendor tree is read from data_dir()/system when installed
+    // there, as the GUI reads it, and from the bundled profiles otherwise.
+    bool resolve_system_preset(DynamicPrintConfig &config, Preset::Type type, const std::string &name,
+                               ForwardCompatibilitySubstitutionRule compatibility_rule, std::string &error);
 
     // Load selections (current print, current filaments, current printer) from config.ini
     // This is done just once on application start up.
@@ -663,13 +670,14 @@ private:
     // Vendor trees loaded by resolve_preset_config's manifest path, so every preset
     // resolved through this bundle shares one load per source root and vendor. The
     // filament library is one such tree, shared by every vendor under its root.
-    std::map<std::tuple<std::string, std::string, ForwardCompatibilitySubstitutionRule>, std::unique_ptr<PresetBundle>>
+    // A tree read from its preset cache is kept apart: its presets carry no source file.
+    std::map<std::tuple<std::string, std::string, ForwardCompatibilitySubstitutionRule, bool>, std::unique_ptr<PresetBundle>>
         m_source_vendor_bundles;
 
     const PresetBundle *load_source_vendor(const boost::filesystem::path &root_dir,
                                            const std::string &vendor_id,
                                            ForwardCompatibilitySubstitutionRule compatibility_rule,
-                                           std::string &error);
+                                           std::string &error, bool allow_cache = false);
 
     // Orca: validation only - flag any printer with two or more compatible
     // filament presets sharing one filament_id (ambiguous AMS subtype match).

src/libslic3r/Print.cpp

@@ -2717,7 +2717,8 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
 
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(m_model.id().id);
+        ctx.id = std::to_string(m_model.id().id);
+        ctx.name = get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.cancellation_check = [this]() { return canceled(); };
         fire_lifecycle_event(LifecycleEvent::SliceStarted, ctx);
@@ -3344,7 +3345,8 @@ void Print::process(long long *time_cost_with_cache, bool use_cache)
 
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(m_model.id().id);
+        ctx.id = std::to_string(m_model.id().id);
+        ctx.name = get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.cancellation_check = [this]() { return canceled(); };
         fire_lifecycle_event(LifecycleEvent::SliceGeometryFinished, ctx);
@@ -4950,7 +4952,8 @@ void Print::export_gcode_from_previous_file(const std::string& file, GCodeProces
 {
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(m_model.id().id);
+        ctx.id = std::to_string(m_model.id().id);
+        ctx.name = get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = file;
         ctx.cancellation_check = [this]() { return canceled(); };
@@ -4980,7 +4983,8 @@ void Print::export_gcode_from_previous_file(const std::string& file, GCodeProces
         BOOST_LOG_TRIVIAL(error) << __FUNCTION__ <<  boost::format(": found errors when process gcode file %1%") %file.c_str();
         {
             LifecycleEventContext ctx;
-            ctx.name = std::to_string(m_model.id().id);
+            ctx.id = std::to_string(m_model.id().id);
+            ctx.name = get_model_name();
             ctx.code = LifecycleEvtCode::Error;
             ctx.msg  = file + "\n" + ex.what();
             ctx.cancellation_check = [this]() { return canceled(); };
@@ -4994,7 +4998,8 @@ void Print::export_gcode_from_previous_file(const std::string& file, GCodeProces
 
     {
         LifecycleEventContext ctx;
-        ctx.name = std::to_string(m_model.id().id);
+        ctx.id = std::to_string(m_model.id().id);
+        ctx.name = get_model_name();
         ctx.code = LifecycleEvtCode::Ok;
         ctx.msg  = file;
         ctx.cancellation_check = [this]() { return canceled(); };

src/libvgcode/src/Shaders.hpp

@@ -34,6 +34,10 @@ static const char* Segments_Vertex_Shader =
 // ORCA: 0 during the shadow caster pass - the bias below shifts eye_position but not
 // world_position, so the caster would write a depth the receiver never looks up.
 "uniform float bias_scale;\n"
+// draw the instances last to first, top layers before the ones they hide, so that early depth
+// rejection discards most of the hidden fragments; set when the camera looks down on the print
+"uniform int reverse_order;\n"
+"uniform int instance_count;\n"
 "in int vertex_id;\n"
 "out vec3 color;\n"
 "// ORCA: realistic view - the light the shadow map is able to block, kept apart from the\n"
@@ -59,7 +63,8 @@ static const char* Segments_Vertex_Shader =
 "  return top_diffuse + front_diffuse + top_specular;\n"
 "}\n"
 "void main() {\n"
-"  int id_a = int(texelFetch(segment_index_tex, gl_InstanceID).r);\n"
+"  int instance = (reverse_order != 0) ? instance_count - 1 - gl_InstanceID : gl_InstanceID;\n"
+"  int id_a = int(texelFetch(segment_index_tex, instance).r);\n"
 "  int id_b = id_a + 1;\n"
 "  vec3 pos_a = texelFetch(position_tex, id_a).xyz;\n"
 "  vec3 pos_b = texelFetch(position_tex, id_b).xyz;\n"

src/libvgcode/src/ViewerImpl.cpp

@@ -763,6 +763,8 @@ void ViewerImpl::init(const std::string& opengl_context_version)
     m_uni_segments_height_width_angle_tex_id = glGetUniformLocation(m_segments_shader_id, "height_width_angle_tex");
     m_uni_segments_colors_tex_id             = glGetUniformLocation(m_segments_shader_id, "color_tex");
     m_uni_segments_segment_index_tex_id      = glGetUniformLocation(m_segments_shader_id, "segment_index_tex");
+    m_uni_segments_reverse_order_id          = glGetUniformLocation(m_segments_shader_id, "reverse_order");
+    m_uni_segments_instance_count_id         = glGetUniformLocation(m_segments_shader_id, "instance_count");
     // ORCA: realistic view
     m_uni_segments_shadow_map_id             = glGetUniformLocation(m_segments_shader_id, "shadow_map");
     m_uni_segments_shadow_light_vp_id        = glGetUniformLocation(m_segments_shader_id, "shadow_light_vp");
@@ -2090,6 +2092,15 @@ void ViewerImpl::render_segments(const Mat4x4& view_matrix, const Mat4x4& projec
     glsafe(glUniformMatrix4fv(m_uni_segments_view_matrix_id, 1, GL_FALSE, view_matrix.data()));
     glsafe(glUniformMatrix4fv(m_uni_segments_projection_matrix_id, 1, GL_FALSE, projection_matrix.data()));
     glsafe(glUniform3fv(m_uni_segments_camera_position_id, 1, camera_position.data()));
+    // The segments come in print order, bottom layer first. Seen from above, that is back to front,
+    // and every hidden fragment is shaded before the one that covers it. Drawing them last to first
+    // lets the depth test reject the hidden ones instead. The camera looks down when the world's
+    // up axis points towards it, which is the view matrix's (2, 2) entry being positive.
+    const bool top_down = !m_rendering_shadow_casters && view_matrix[10] > 0.0f;
+    glsafe(glUniform1i(m_uni_segments_reverse_order_id, top_down ? 1 : 0));
+#ifndef ENABLE_OPENGL_ES
+    glsafe(glUniform1i(m_uni_segments_instance_count_id, static_cast<int>(m_enabled_segments_count)));
+#endif // ENABLE_OPENGL_ES
     // ORCA: realistic view. The depth pass writes the map it would otherwise read, so it shades
     // with the lookup off.
     glsafe(glUniform1i(m_uni_segments_shadow_map_id, m_shadow_map_texture_unit));

src/libvgcode/src/ViewerImpl.hpp

@@ -362,6 +362,8 @@ private:
     int m_uni_segments_height_width_angle_tex_id{ -1 };
     int m_uni_segments_colors_tex_id{ -1 };
     int m_uni_segments_segment_index_tex_id{ -1 };
+    int m_uni_segments_reverse_order_id{ -1 };
+    int m_uni_segments_instance_count_id{ -1 };
     int m_uni_segments_shadow_map_id{ -1 };
     int m_uni_segments_shadow_light_vp_id{ -1 };
     int m_uni_segments_shadow_intensity_id{ -1 };

src/slic3r/GUI/Plater.cpp

@@ -12800,8 +12800,6 @@ void Plater::priv::on_process_completed(SlicingProcessCompletedEvent &evt)
     notification_manager->set_slicing_progress_export_possible();
 
     // Reset the "export G-code path" name, so that the automatic background processing will be enabled again.
-    const std::string lifecycle_job_name = this->background_process.fff_print() ?
-        this->background_process.fff_print()->output_filename() : std::string();
     this->background_process.reset_export();
     // This bool stops showing export finished notification even when process_completed_with_error is false
     bool has_error = false;
@@ -12848,8 +12846,18 @@ void Plater::priv::on_process_completed(SlicingProcessCompletedEvent &evt)
 
     {
         Slic3r::LifecycleEventContext ctx;
-        ctx.name = lifecycle_job_name;
-        ctx.code = evt.cancelled() ? Slic3r::LifecycleEvtCode::Warn : (has_error ? Slic3r::LifecycleEvtCode::Error : Slic3r::LifecycleEvtCode::Ok);
+        if (const PrintBase* print = this->background_process.current_print()) {
+            const Model& model = print->model();
+            ctx.id             = std::to_string(model.id().id);
+            if (model.model_info)
+                ctx.name = model.model_info->model_name;
+        } else {
+            // Realistically Printbase* print will never be null because select_technology already asserts an active print
+            // and the worker thread asserts it before processing.
+            BOOST_LOG_TRIVIAL(warning) << __FUNCTION__ << ": slicing completed without an active print; lifecycle event has no model ID";
+        }
+        ctx.code = evt.cancelled() ? Slic3r::LifecycleEvtCode::Warn :
+                                     (has_error ? Slic3r::LifecycleEvtCode::Error : Slic3r::LifecycleEvtCode::Ok);
         ctx.msg  = evt.cancelled() ? "cancelled" : (has_error ? lifecycle_error_msg : std::string());
         Slic3r::fire_lifecycle_event(Slic3r::LifecycleEvent::SlicingJobComplete, ctx);
     }

src/slic3r/Utils/PrintHost.cpp

@@ -6,6 +6,7 @@
 #include <boost/optional.hpp>
 #include <boost/log/trivial.hpp>
 #include <boost/filesystem.hpp>
+#include <nlohmann/json.hpp>
 
 #include <wx/string.h>
 #include <wx/app.h>
@@ -115,10 +116,67 @@ std::string PrintHost::get_print_host_webui(DynamicPrintConfig* config)
     return webui_url;
 }
 
+namespace {
+
+// Moonraker (Klipper's API server) reports a raised exception as { "error": { "code", "message", "traceback" } }
+// under every host type that connects to it, often with the cause only in the traceback. Returns the reason to show,
+// or empty for any other body.
+std::string moonraker_error_reason(const std::string &body)
+{
+    const auto root = nlohmann::json::parse(body, nullptr, false);
+    const auto err  = root.find("error");
+    if (err == root.end())
+        return {};
+    const auto message   = err->find("message");
+    const auto traceback = err->find("traceback");
+    if (message == err->end() || traceback == err->end() || !message->is_string() || !traceback->is_string())
+        return {};
+
+    const auto &msg = message->get_ref<const std::string &>();
+    const auto &tb  = traceback->get_ref<const std::string &>();
+    if (msg.empty())
+        return {};
+    const auto end = tb.find_last_not_of(" \t\r\n");
+    if (end == std::string::npos)
+        return msg;
+
+    // Chained exceptions each start a new traceback; the one that failed the request is the last.
+    const auto header = tb.rfind("Traceback (most recent call last):", end);
+
+    // Tornado renders a raised HTTPError as "HTTP <code>: <reason>[ (<detail>)]", and the detail may span lines.
+    const auto code = err->find("code");
+    if (code != err->end() && code->is_number_integer()) {
+        const std::string marker = "HTTP " + std::to_string(code->get<int>()) + ": ";
+        const auto        pos    = tb.rfind(marker, end);
+        if (pos != std::string::npos && (header == std::string::npos || pos > header) && pos + marker.size() <= end) {
+            const std::string reason = tb.substr(pos + marker.size(), end + 1 - pos - marker.size());
+            // An HTTPError whose detail equals its reason, like HTTPError(401, "Unauthorized"), renders the phrase twice.
+            return reason == msg + " (" + msg + ")" ? msg : reason;
+        }
+    }
+
+    // Any other exception's type and message are everything from the first unindented line after its frames.
+    auto begin = (header == std::string::npos) ? std::string::npos : tb.find('\n', header);
+    while (begin != std::string::npos && begin < end) {
+        ++begin;
+        if (tb[begin] != ' ' && tb[begin] != '\r' && tb[begin] != '\n')
+            break;
+        begin = tb.find('\n', begin);
+    }
+    if (begin == std::string::npos || begin > end) {
+        const auto nl = tb.rfind('\n', end);
+        begin         = (nl == std::string::npos) ? 0 : nl + 1;
+    }
+    return msg + " (" + tb.substr(begin, end + 1 - begin) + ")";
+}
+
+} // namespace
+
 wxString PrintHost::format_error(const std::string &body, const std::string &error, unsigned status) const
 {
     if (status != 0) {
-        auto wxbody = wxString::FromUTF8(body.data());
+        const std::string reason = moonraker_error_reason(body);
+        auto wxbody = wxString::FromUTF8(reason.empty() ? body : reason);
         return wxString::Format("HTTP %u: %s", status, wxbody);
     } else {
         if (error.find("curl:Timeout was reached") != std::string::npos) {

tests/cli/CMakeLists.txt

@@ -15,3 +15,11 @@ set_tests_properties(cli_strict_mode PROPERTIES
     LABELS "CLI;RequiresApp"
     SKIP_RETURN_CODE 77
     TIMEOUT 900)
+
+add_test(NAME cli_project_missing_keys
+    COMMAND bash ${CMAKE_CURRENT_SOURCE_DIR}/test_cli_project_missing_keys.sh $<TARGET_FILE:OrcaSlicer> ${ORCA_CLI_TEST_PYTHON}
+        ${CMAKE_SOURCE_DIR}/resources/profiles/BBL)
+set_tests_properties(cli_project_missing_keys PROPERTIES
+    LABELS "CLI;RequiresApp"
+    SKIP_RETURN_CODE 77
+    TIMEOUT 900)

tests/cli/test_cli_project_missing_keys.sh

@@ -0,0 +1,96 @@
+#!/usr/bin/env bash
+# End-to-end check that the CLI loads a project's printer and process settings as the GUI does.
+#
+# The GUI takes every key a project does not list as changed from the project's current system preset:
+# keys saved before an option existed, and keys holding an older system value. Keys the project lists
+# in different_settings_to_system keep the project's value. A project is exported from the shipped
+# Bambu Lab P1S presets; one printer key and one process key are removed, one printer key and one
+# process key are changed without being listed, one key is changed and listed, and it is sliced again.
+#
+# usage: test_cli_project_missing_keys.sh <orca-slicer binary> <python3> <resources/profiles/BBL>
+set -u
+
+BIN="${1:-}"
+PY="${2:-python3}"
+PROFILES="${3:-}"
+# 77 is the test's SKIP_RETURN_CODE.
+[ -x "$BIN" ] || { echo "SKIP: orca-slicer binary not found: $BIN"; exit 77; }
+[ -d "$PROFILES" ] || { echo "FAIL: profiles directory not found: $PROFILES"; exit 1; }
+
+WORK="$(mktemp -d "${TMPDIR:-/tmp}/orca-cli-missing-keys.XXXXXX")"
+trap 'rm -rf "$WORK"' EXIT
+
+"$PY" - "$WORK/cube.stl" <<'EOF'
+import sys
+
+v = [(x, y, z) for z in (0, 10) for y in (0, 10) for x in (0, 10)]
+with open(sys.argv[1], "w") as f:
+    f.write("solid cube\n")
+    for a, b, c, d in ((0, 2, 3, 1), (4, 5, 7, 6), (0, 1, 5, 4), (2, 6, 7, 3), (0, 4, 6, 2), (1, 3, 7, 5)):
+        for tri in ((v[a], v[b], v[c]), (v[a], v[c], v[d])):
+            f.write("facet normal 0 0 0\nouter loop\n")
+            for p in tri:
+                f.write("vertex %g %g %g\n" % p)
+            f.write("endloop\nendfacet\n")
+    f.write("endsolid cube\n")
+EOF
+
+# slice <tag> <input> [option...]: slice into $WORK/<tag>/out.3mf with a fresh data directory.
+slice() {
+    local out="$WORK/$1" input="$2"; shift 2
+    mkdir -p "$out"
+    timeout 300 "$BIN" --datadir "$out/datadir" "$@" --slice 0 --outputdir "$out" --export-3mf out.3mf "$input" \
+        > "$out/log" 2>&1 || { echo "FAIL: $1: orca-slicer exited $?"; tail -n 40 "$out/log"; exit 1; }
+}
+
+slice base "$WORK/cube.stl" \
+    --load-settings "$PROFILES/machine/Bambu Lab P1S 0.4 nozzle.json;$PROFILES/process/0.20mm Standard @BBL X1C.json" \
+    --load-filaments "$PROFILES/filament/Bambu PLA Basic @BBL P1S 0.4 nozzle.json"
+
+# The removed keys, with their option defaults from PrintConfig.cpp; stale keys changed without being
+# listed as different, which must come back with the system value; and a listed key the project keeps.
+"$PY" - "$WORK/base/out.3mf" "$WORK/old.3mf" <<'EOF' || exit $?
+import json, sys, zipfile
+
+src, dst = sys.argv[1], sys.argv[2]
+missing = {"extruder_clearance_dist_to_rod": "40", "sparse_infill_density": "20%"}
+with zipfile.ZipFile(src) as zin, zipfile.ZipFile(dst, "w", zipfile.ZIP_DEFLATED) as zout:
+    for item in zin.infolist():
+        data = zin.read(item.filename)
+        if item.filename == "Metadata/project_settings.config":
+            config = json.loads(data)
+            for key, default in missing.items():
+                if config[key] == default:
+                    print("SKIP: %s is %s in the system preset, the option default, so the test cannot tell them apart" % (key, default))
+                    sys.exit(77)
+            expected = {key: config.pop(key) for key in missing}
+            for key in ("top_shell_layers", "extruder_clearance_height_to_rod"):
+                expected[key] = config[key]
+                config[key] = str(int(float(config[key])) + 1)
+            expected["wall_loops"] = str(int(config["wall_loops"]) + 1)
+            config["wall_loops"] = expected["wall_loops"]
+            different = config["different_settings_to_system"]
+            different[0] = ";".join([k for k in different[0].split(";") if k] + ["wall_loops"])
+            data = json.dumps(config, indent=4)
+        zout.writestr(item, data)
+with open(dst + ".expected.json", "w") as f:
+    json.dump(expected, f)
+EOF
+
+slice project "$WORK/old.3mf"
+
+"$PY" - "$WORK/project/out.3mf" "$WORK/old.3mf.expected.json" <<'EOF'
+import json, sys, zipfile
+
+with zipfile.ZipFile(sys.argv[1]) as z:
+    config = json.loads(z.read("Metadata/project_settings.config"))
+with open(sys.argv[2]) as f:
+    expected = json.load(f)
+errors = ["%s is %r, want %r" % (key, config.get(key), want) for key, want in expected.items() if config.get(key) != want]
+for e in errors:
+    print("FAIL: " + e)
+sys.exit(1 if errors else 0)
+EOF
+status=$?
+[ "$status" -eq 0 ] || { tail -n 40 "$WORK/project/log"; exit 1; }
+echo "PASS"

tests/fff_print/test_print.cpp

@@ -15,6 +15,9 @@
 #include "libslic3r/Layer.hpp"
 #include "libslic3r/Model.hpp"
 #include "libslic3r/GCodeReader.hpp"
+#include "libslic3r/GCode/GCodeProcessor.hpp"
+#include "libslic3r/Exception.hpp"
+#include "libslic3r/LifecycleEvents.hpp"
 
 #include "test_helpers.hpp"
 #include "test_utils.hpp"
@@ -22,7 +25,10 @@
 #include <algorithm>
 #include <fstream>
 #include <iterator>
+#include <memory>
 #include <string_view>
+#include <utility>
+#include <vector>
 
 using namespace Slic3r;
 using namespace Slic3r::Test;
@@ -224,8 +230,88 @@ std::string resolved_output_name(Model& model, const std::string& format, const
     return print.output_filename(filename_base);
 }
 
+struct ScopedLifecycleHook
+{
+    explicit ScopedLifecycleHook(LifecycleHookFn hook) { set_lifecycle_hook_fn(std::move(hook)); }
+    ~ScopedLifecycleHook() { set_lifecycle_hook_fn(nullptr); }
+};
+
 } // namespace
 
+TEST_CASE("Slicing lifecycle events identify the model", "[Print][LifecycleEvents]")
+{
+    struct ObservedEvent {
+        LifecycleEvent event;
+        std::string id;
+        std::string name;
+    };
+    std::vector<ObservedEvent> events;
+    ScopedLifecycleHook hook([&](LifecycleEvent event, const LifecycleEventContext& ctx) {
+        events.push_back({ event, ctx.id, ctx.name });
+    });
+
+    Print print;
+    Model model;
+    ModelInfo info;
+    info.model_name = "Lifecycle test model";
+    model.model_info = std::make_shared<ModelInfo>(std::move(info));
+    init_print({cube(20)}, print, model);
+
+    print.process();
+    ScopedTemporaryFile temp(".gcode");
+    print.export_gcode(temp.string(), nullptr, nullptr);
+    GCodeProcessorResult result;
+    print.export_gcode_from_previous_file(temp.string(), &result);
+
+    const std::string expected_id = std::to_string(print.model().id().id);
+    const std::vector<LifecycleEvent> expected_events = {
+        LifecycleEvent::SliceStarted,
+        LifecycleEvent::SliceGeometryFinished,
+        LifecycleEvent::GCodeExportStarted,
+        LifecycleEvent::GCodeExportFinished,
+        LifecycleEvent::GCodeExportStarted,
+        LifecycleEvent::GCodeExportFinished,
+    };
+    REQUIRE(events.size() == expected_events.size());
+    for (size_t i = 0; i < expected_events.size(); ++i) {
+        CHECK(events[i].event == expected_events[i]);
+        CHECK(events[i].id == expected_id);
+        CHECK(events[i].name == "Lifecycle test model");
+    }
+}
+
+TEST_CASE("Slicing lifecycle event name is empty without model metadata", "[Print][LifecycleEvents]")
+{
+    std::string event_id;
+    std::string event_name = "unset";
+    ScopedLifecycleHook hook([&](LifecycleEvent event, const LifecycleEventContext& ctx) {
+        if (event == LifecycleEvent::SliceStarted) {
+            event_id = ctx.id;
+            event_name = ctx.name;
+        }
+    });
+
+    Print print;
+    Model model;
+    init_print({cube(20)}, print, model);
+    print.process();
+
+    CHECK(event_id == std::to_string(print.model().id().id));
+    CHECK(event_name.empty());
+}
+
+TEST_CASE("Output filenames with numeric statistics fail before slicing finishes", "[Print][Regression]")
+{
+    DynamicPrintConfig config = DynamicPrintConfig::full_print_config();
+    config.set_key_value("filename_format", new ConfigOptionString("{int(total_weight*10) / 10.0}"));
+
+    Print print;
+    Model model;
+    init_print({cube(20)}, print, model, config);
+
+    CHECK_THROWS_AS(print.output_filename(), PlaceholderParserError);
+}
+
 TEST_CASE("Print: {first_object_name} names the first printable object on the plate", "[Print]")
 {
     Model model;

tests/libslic3r/test_3mf.cpp

@@ -17,7 +17,6 @@
 #include <nlohmann/json.hpp>
 
 #include <boost/filesystem/operations.hpp>
-#include <boost/nowide/fstream.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <algorithm>
 
@@ -1462,79 +1461,3 @@ SCENARIO("bbs_3mf_is_published detects only genuinely published 3MFs", "[3mf]")
     }
 }
 
-// Writes a single-entry zip whose central directory carries a zip64 record declaring an
-// uncompressed size beyond what the 32-bit expat buffer API can take, while the deflated
-// payload inflates to only ~64 KiB. Built by hand because miniz never writes a size that
-// disagrees with the data.
-static void write_zip_with_oversized_entry(const std::string& path, const std::string& entry)
-{
-    const std::string xml = "<?xml version=\"1.0\"?><!--" + std::string(65536, 'A') + "--><a/>";
-    size_t comp_len = 0;
-    void*  comp     = tdefl_compress_mem_to_heap(xml.data(), xml.size(), &comp_len, TDEFL_DEFAULT_MAX_PROBES);
-    REQUIRE(comp != nullptr);
-    const std::string deflated(static_cast<const char*>(comp), comp_len);
-    mz_free(comp);
-    const uint32_t crc = static_cast<uint32_t>(mz_crc32(MZ_CRC32_INIT, reinterpret_cast<const unsigned char*>(xml.data()), xml.size()));
-    const uint64_t claimed_size = (uint64_t(1) << 32) + 16;
-
-    std::string out;
-    auto put = [&out](uint64_t v, int bytes) {
-        for (int i = 0; i < bytes; ++i)
-            out.push_back(static_cast<char>((v >> (8 * i)) & 0xFF));
-    };
-    // local file header, with the true sizes
-    put(0x04034b50, 4); put(45, 2); put(0, 2); put(8, 2); put(0, 2); put(0, 2);
-    put(crc, 4); put(deflated.size(), 4); put(xml.size(), 4); put(entry.size(), 2); put(0, 2);
-    out += entry + deflated;
-    // central directory header, sizes deferred to the zip64 extra field
-    const size_t cd_offset = out.size();
-    put(0x02014b50, 4); put(45, 2); put(45, 2); put(0, 2); put(8, 2); put(0, 2); put(0, 2);
-    put(crc, 4); put(0xFFFFFFFF, 4); put(0xFFFFFFFF, 4); put(entry.size(), 2); put(20, 2);
-    put(0, 2); put(0, 2); put(0, 2); put(0, 4); put(0, 4);
-    out += entry;
-    put(0x0001, 2); put(16, 2); put(claimed_size, 8); put(deflated.size(), 8);
-    const size_t cd_size = out.size() - cd_offset;
-    // end of central directory
-    put(0x06054b50, 4); put(0, 2); put(0, 2); put(1, 2); put(1, 2);
-    put(cd_size, 4); put(cd_offset, 4); put(0, 2);
-
-    boost::nowide::ofstream f(path, std::ios::binary);
-    REQUIRE(f.good());
-    f.write(out.data(), static_cast<std::streamsize>(out.size()));
-    REQUIRE(f.good());
-}
-
-TEST_CASE("3MF XML entries declaring more than an int can hold fail to load", "[3mf]") {
-    ScopedTemporaryFile temp(".3mf");
-    const std::string   path = temp.string();
-
-    SECTION("BBS importer") {
-        write_zip_with_oversized_entry(path, "_rels/.rels");
-        Model                     model;
-        DynamicPrintConfig        config;
-        ConfigSubstitutionContext ctxt{ForwardCompatibilitySubstitutionRule::Enable};
-        PlateDataPtrs             plates;
-        std::vector<Preset*>      project_presets;
-        bool                      is_bbl_3mf = false, is_orca_3mf = false;
-        Semver                    file_version;
-        bool                      loaded = true;
-        REQUIRE_NOTHROW(loaded = load_bbs_3mf(path.c_str(), &config, &ctxt, &model, &plates, &project_presets, &is_bbl_3mf,
-                                              &is_orca_3mf, &file_version, nullptr, LoadStrategy::LoadModel | LoadStrategy::LoadConfig));
-        CHECK_FALSE(loaded);
-        release_PlateData_list(plates);
-    }
-    SECTION("PrusaSlicer importer") {
-        write_zip_with_oversized_entry(path, "Metadata/Slic3r_PE_model.config");
-        Model                     model;
-        DynamicPrintConfig        config;
-        ConfigSubstitutionContext ctxt{ForwardCompatibilitySubstitutionRule::Disable};
-        bool                      loaded = true;
-        REQUIRE_NOTHROW(loaded = load_3mf(path.c_str(), config, ctxt, &model, false));
-        CHECK_FALSE(loaded);
-    }
-    SECTION("PrusaSlicer fingerprint probe") {
-        write_zip_with_oversized_entry(path, "3D/3dmodel.model");
-        PrusaFileParser parser;
-        CHECK_FALSE(parser.check_3mf_from_prusa(path));
-    }
-}

tests/libslic3r/test_preset_bundle_loading.cpp

@@ -5405,6 +5405,35 @@ struct ScopedDataDir
     ~ScopedDataDir() { set_data_dir(previous); }
 };
 
+// resources_dir() is process-wide too; system preset lookups scan its profiles directory.
+struct ScopedResourcesDir
+{
+    std::string previous = resources_dir();
+    explicit ScopedResourcesDir(const fs::path &dir) { set_resources_dir(dir.string()); }
+    ~ScopedResourcesDir() { set_resources_dir(previous); }
+};
+
+// An "Acme" vendor under root whose "Acme Printer" inherits extruder_clearance_dist_to_rod from an
+// abstract base, with the printer in a nested sub_path so the name cannot be derived from the file.
+void write_acme_printer_vendor(const fs::path &root, double dist_to_rod)
+{
+    const fs::path machine_dir = root / "Acme" / "machine";
+    fs::create_directories(machine_dir / "nested");
+    std::ofstream((root / "Acme.json").string())
+        << R"({"version":"1.0.0","name":"Acme",)"
+        << R"("machine_model_list":[{"name":"Acme One","sub_path":"machine/model.json"}],"machine_list":[)"
+        << R"({"name":"fdm_acme_common","sub_path":"machine/base.json"},)"
+        << R"({"name":"Acme Printer","sub_path":"machine/nested/printer.json"}]})";
+    std::ofstream((machine_dir / "model.json").string())
+        << R"({"type":"machine_model","name":"Acme One","nozzle_diameter":"0.4"})";
+    std::ofstream((machine_dir / "base.json").string())
+        << R"({"type":"machine","name":"fdm_acme_common","from":"system","instantiation":"false",)"
+        << R"("extruder_clearance_dist_to_rod":")" << dist_to_rod << R"("})";
+    std::ofstream((machine_dir / "nested" / "printer.json").string())
+        << R"({"type":"machine","name":"Acme Printer","from":"system","instantiation":"true","inherits":"fdm_acme_common",)"
+        << R"("printer_model":"Acme One","printer_variant":"0.4"})";
+}
+
 std::string read_file(const fs::path &file)
 {
     std::ifstream in(file.string(), std::ios::binary);
@@ -5482,3 +5511,230 @@ TEST_CASE("Config import confines zip entries, preset names and bundle ids to th
         CHECK_FALSE(any_filename_contains(temp_dir.path(), "bundle-escape"));
     }
 }
+
+TEST_CASE("A system preset resolves by name from the bundled profiles", "[Preset][Bundle]")
+{
+    ScopedTemporaryDir temp_dir;
+    ScopedDataDir      data(temp_dir.path() / "data");
+    ScopedResourcesDir resources(temp_dir.path() / "resources");
+    write_acme_printer_vendor(temp_dir.path() / "resources" / "profiles", 33.);
+
+    PresetBundle       bundle;
+    DynamicPrintConfig config;
+    std::string        error;
+    REQUIRE(bundle.resolve_system_preset(config, Preset::TYPE_PRINTER, "Acme Printer",
+                                         ForwardCompatibilitySubstitutionRule::EnableSilent, error));
+    CHECK(error.empty());
+    CHECK_THAT(config.opt_float("extruder_clearance_dist_to_rod"), Catch::Matchers::WithinAbs(33., 1e-6));
+}
+
+TEST_CASE("A system preset resolves from the data directory copy of its vendor", "[Preset][Bundle]")
+{
+    ScopedTemporaryDir temp_dir;
+    ScopedDataDir      data(temp_dir.path() / "data");
+    ScopedResourcesDir resources(temp_dir.path() / "resources");
+    write_acme_printer_vendor(temp_dir.path() / "resources" / "profiles", 33.);
+    write_acme_printer_vendor(temp_dir.path() / "data" / PRESET_SYSTEM_DIR, 35.);
+
+    PresetBundle       bundle;
+    DynamicPrintConfig config;
+    std::string        error;
+    REQUIRE(bundle.resolve_system_preset(config, Preset::TYPE_PRINTER, "Acme Printer",
+                                         ForwardCompatibilitySubstitutionRule::EnableSilent, error));
+    CHECK_THAT(config.opt_float("extruder_clearance_dist_to_rod"), Catch::Matchers::WithinAbs(35., 1e-6));
+}
+
+TEST_CASE("A system preset resolves from a vendor shipped as its preset cache alone", "[Preset][Bundle]")
+{
+    ScopedTemporaryDir temp_dir;
+    ScopedDataDir      data(temp_dir.path() / "data");
+    ScopedResourcesDir resources(temp_dir.path() / "resources");
+    const fs::path     profiles = temp_dir.path() / "resources" / "profiles";
+    write_acme_printer_vendor(profiles, 33.);
+
+    PresetBundle writer;
+    writer.set_generate_vendor_caches(true);
+    writer.load_vendor_configs_from_json(profiles.string(), "Acme", PresetBundle::LoadSystem,
+                                         ForwardCompatibilitySubstitutionRule::EnableSilent);
+    REQUIRE(fs::exists(profiles / "Acme.opc"));
+    // Release builds ship the cache and drop the profile JSONs, manifest included.
+    fs::remove(profiles / "Acme.json");
+    fs::remove_all(profiles / "Acme");
+
+    PresetBundle       bundle;
+    DynamicPrintConfig config;
+    std::string        error;
+    REQUIRE(bundle.resolve_system_preset(config, Preset::TYPE_PRINTER, "Acme Printer",
+                                         ForwardCompatibilitySubstitutionRule::EnableSilent, error));
+    CHECK_THAT(config.opt_float("extruder_clearance_dist_to_rod"), Catch::Matchers::WithinAbs(33., 1e-6));
+}
+
+TEST_CASE("A system preset no vendor lists is not resolved", "[Preset][Bundle]")
+{
+    ScopedTemporaryDir temp_dir;
+    ScopedDataDir      data(temp_dir.path() / "data");
+    ScopedResourcesDir resources(temp_dir.path() / "resources");
+    write_acme_printer_vendor(temp_dir.path() / "resources" / "profiles", 33.);
+
+    PresetBundle       bundle;
+    DynamicPrintConfig config;
+    std::string        error;
+    CHECK_FALSE(bundle.resolve_system_preset(config, Preset::TYPE_PRINTER, "Unknown Printer",
+                                             ForwardCompatibilitySubstitutionRule::EnableSilent, error));
+    CHECK_FALSE(error.empty());
+}
+
+namespace {
+
+// A default preset config for type, built the way PresetBundle builds its default presets.
+DynamicPrintConfig external_default_config(Preset::Type type)
+{
+    DynamicPrintConfig config;
+    config.apply_only(static_cast<const PrintRegionConfig &>(FullPrintConfig::defaults()),
+                      type == Preset::TYPE_PRINTER ? Preset::printer_options() : Preset::print_options());
+    Preset::inherits(config);
+    return config;
+}
+
+// A find_base callback that counts its calls and returns base.
+auto base_finder(DynamicPrintConfig *base, int &calls)
+{
+    return [base, &calls](const std::string &) {
+        ++calls;
+        return base;
+    };
+}
+
+} // namespace
+
+TEST_CASE("A key missing from a project takes the default preset value when there is no base", "[Preset][ExternalPreset]")
+{
+    DynamicPrintConfig defaults = external_default_config(Preset::TYPE_PRINT);
+    defaults.set("wall_loops", 7, true);
+    const DynamicPrintConfig project;
+    int calls = 0;
+
+    const DynamicPrintConfig config = Preset::load_external_config(Preset::TYPE_PRINT, defaults, project, {"sparse_infill_density"},
+                                                                   base_finder(nullptr, calls));
+    CHECK(calls == 1);
+    CHECK(config.opt_int("wall_loops") == 7);
+}
+
+TEST_CASE("A key missing from a project takes its base preset value", "[Preset][ExternalPreset]")
+{
+    DynamicPrintConfig defaults = external_default_config(Preset::TYPE_PRINT);
+    defaults.set("wall_loops", 7, true);
+    DynamicPrintConfig base = defaults;
+    base.set("wall_loops", 5, true);
+    const DynamicPrintConfig project;
+    int calls = 0;
+
+    const DynamicPrintConfig config = Preset::load_external_config(Preset::TYPE_PRINT, defaults, project, {"sparse_infill_density"},
+                                                                   base_finder(&base, calls));
+    CHECK(config.opt_int("wall_loops") == 5);
+}
+
+TEST_CASE("A project key listed as different keeps the project value", "[Preset][ExternalPreset]")
+{
+    const DynamicPrintConfig defaults = external_default_config(Preset::TYPE_PRINT);
+    DynamicPrintConfig       base     = defaults;
+    base.set("wall_loops", 5, true);
+    DynamicPrintConfig project;
+    project.set("wall_loops", 4, true);
+    int calls = 0;
+
+    const DynamicPrintConfig config = Preset::load_external_config(Preset::TYPE_PRINT, defaults, project, {"wall_loops"},
+                                                                   base_finder(&base, calls));
+    CHECK(config.opt_int("wall_loops") == 4);
+}
+
+TEST_CASE("A project key not listed as different is refreshed to the base value", "[Preset][ExternalPreset]")
+{
+    const DynamicPrintConfig defaults = external_default_config(Preset::TYPE_PRINT);
+    DynamicPrintConfig       base     = defaults;
+    base.set("wall_loops", 5, true);
+    DynamicPrintConfig project;
+    project.set("wall_loops", 4, true);
+    project.set("inherits", "Base Process", true);
+    std::string inherits;
+
+    const DynamicPrintConfig config = Preset::load_external_config(Preset::TYPE_PRINT, defaults, project, {"sparse_infill_density"},
+                                                                   [&base, &inherits](const std::string &name) {
+                                                                       inherits = name;
+                                                                       return &base;
+                                                                   });
+    CHECK(inherits == "Base Process");
+    CHECK(config.opt_int("wall_loops") == 5);
+}
+
+TEST_CASE("An empty different settings list keeps the project values without a base", "[Preset][ExternalPreset]")
+{
+    DynamicPrintConfig defaults = external_default_config(Preset::TYPE_PRINT);
+    defaults.set("top_shell_layers", 7, true);
+    DynamicPrintConfig base = defaults;
+    base.set("wall_loops", 5, true);
+    base.set("top_shell_layers", 9, true);
+    DynamicPrintConfig project;
+    project.set("wall_loops", 4, true);
+    int calls = 0;
+
+    const DynamicPrintConfig config = Preset::load_external_config(Preset::TYPE_PRINT, defaults, project, {}, base_finder(&base, calls));
+    CHECK(calls == 0);
+    CHECK(config.opt_int("wall_loops") == 4);
+    CHECK(config.opt_int("top_shell_layers") == 7);
+}
+
+TEST_CASE("Print-host keys are never taken from a project", "[Preset][ExternalPreset]")
+{
+    DynamicPrintConfig defaults = external_default_config(Preset::TYPE_PRINTER);
+    defaults.set("print_host", "", true);
+    defaults.set("printhost_apikey", "", true);
+    DynamicPrintConfig project;
+    project.set("print_host", "http://project-host", true);
+    project.set("printhost_apikey", "project-key", true);
+    project.set("printer_notes", "project notes", true);
+    t_config_option_keys keys;
+    int calls = 0;
+
+    const DynamicPrintConfig config = Preset::load_external_config(Preset::TYPE_PRINTER, defaults, project, {"printer_notes"},
+                                                                   base_finder(nullptr, calls), &keys);
+    CHECK(config.opt_string("print_host").empty());
+    CHECK(config.opt_string("printhost_apikey").empty());
+    CHECK(config.opt_string("printer_notes") == "project notes");
+    CHECK_FALSE(contains_key(keys, "print_host"));
+    CHECK_FALSE(contains_key(keys, "printhost_apikey"));
+    CHECK(contains_key(keys, "printer_notes"));
+}
+
+TEST_CASE("A per-variant project value maps onto its base preset's variant layout", "[Preset][ExternalPreset]")
+{
+    const DynamicPrintConfig defaults = external_default_config(Preset::TYPE_PRINT);
+    DynamicPrintConfig       base     = defaults;
+    base.set_key_value("print_extruder_id", new ConfigOptionInts({1, 1}));
+    base.set_key_value("print_extruder_variant", new ConfigOptionStrings({"Direct Drive Standard", "Direct Drive High Flow"}));
+    base.set_key_value("outer_wall_speed", new ConfigOptionFloats({200., 300.}));
+    base.set_key_value("inner_wall_speed", new ConfigOptionFloats({250., 350.}));
+    // A project saved before its printer had a High Flow variant.
+    DynamicPrintConfig project;
+    project.set_key_value("print_extruder_id", new ConfigOptionInts({1}));
+    project.set_key_value("print_extruder_variant", new ConfigOptionStrings({"Direct Drive Standard"}));
+    project.set_key_value("outer_wall_speed", new ConfigOptionFloats({100.}));
+    project.set_key_value("inner_wall_speed", new ConfigOptionFloats({150.}));
+    int calls = 0;
+
+    const DynamicPrintConfig config = Preset::load_external_config(Preset::TYPE_PRINT, defaults, project, {"outer_wall_speed"},
+                                                                   base_finder(&base, calls));
+    CHECK(config.option<ConfigOptionStrings>("print_extruder_variant")->values ==
+          std::vector<std::string>{"Direct Drive Standard", "Direct Drive High Flow"});
+    // The listed key keeps the project's Standard value and takes High Flow from the base.
+    check_double_vector(config.option<ConfigOptionFloats>("outer_wall_speed")->values, {100., 300.});
+    check_double_vector(config.option<ConfigOptionFloats>("inner_wall_speed")->values, {250., 350.});
+}
+
+TEST_CASE("A project's different settings always keep the preset bookkeeping keys", "[Preset][ExternalPreset]")
+{
+    const std::set<std::string> keys = PresetBundle::project_different_keys(escape_strings_cstyle({"wall_loops", "top_shell_layers"}));
+    for (const char *key : {"wall_loops", "top_shell_layers", "inherits", "print_settings_id", "filament_settings_id", "printer_settings_id"})
+        CHECK(keys.count(key) == 1);
+    CHECK(PresetBundle::project_different_keys(std::string()).count("inherits") == 1);
+}

tests/slic3rutils/CMakeLists.txt

@@ -18,6 +18,7 @@ add_executable(${_TEST_NAME}_tests
     test_plugin_install.cpp
     test_plugin_lifecycle.cpp
     test_plugin_printer_agent.cpp
+    test_printhost.cpp
     test_slicing_pipeline_bindings.cpp
     test_slicing_pipeline_config.cpp
     test_plugin_sort.cpp

tests/slic3rutils/test_printhost.cpp

@@ -0,0 +1,213 @@
+#include <catch2/catch_all.hpp>
+
+#include <nlohmann/json.hpp>
+
+#include "slic3r/Utils/PrintHost.hpp"
+
+using namespace Slic3r;
+
+namespace {
+
+class TestPrintHost : public PrintHost
+{
+public:
+    using PrintHost::format_error;
+
+    const char* get_name() const override { return "Test"; }
+    bool test(wxString&) const override { return true; }
+    wxString get_test_ok_msg() const override { return {}; }
+    wxString get_test_failed_msg(wxString&) const override { return {}; }
+    bool upload(PrintHostUpload, ProgressFn, ErrorFn, InfoFn) const override { return true; }
+    bool has_auto_discovery() const override { return false; }
+    bool can_test() const override { return false; }
+    PrintHostPostUploadActions get_post_upload_actions() const override { return {}; }
+    std::string get_host() const override { return {}; }
+};
+
+std::string format_error(const std::string& body, const std::string& error, unsigned status)
+{
+    return TestPrintHost().format_error(body, error, status).ToStdString();
+}
+
+std::string envelope(int code, const std::string& message, const std::string& traceback)
+{
+    return nlohmann::json{{"error", {{"code", code}, {"message", message}, {"traceback", traceback}}}}.dump();
+}
+
+std::string moonraker_error(int code, const std::string& message, const std::string& detail = {})
+{
+    std::string line = "tornado.web.HTTPError: HTTP " + std::to_string(code) + ": " + message;
+    if (!detail.empty())
+        line += " (" + detail + ")";
+    return envelope(code, message, "Traceback (most recent call last):\n  ...\n" + line + "\n");
+}
+
+// A real Moonraker body for uploading a file that is being printed.
+constexpr const char* k_busy_file_403 =
+    R"JSON({"error": {"code": 403, "message": "Forbidden", "traceback": "Traceback (most recent call last):\n\n  File \"/home/lava/moonraker/moonraker/components/file_manager/file_manager.py\", line 1017, in _finish_gcode_upload\n    can_start = self._handle_operation_check(check_path)\n                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\nmoonraker.utils.exceptions.ServerError: File currently in use\n\nDuring handling of the above exception, another exception occurred:\n\nTraceback (most recent call last):\n\n  File \"/home/lava/moonraker/moonraker/components/application.py\", line 1069, in post\n    raise tornado.web.HTTPError(\ntornado.web.HTTPError: HTTP 403: Forbidden (File is loaded, upload not permitted)\n"}})JSON";
+
+} // namespace
+
+TEST_CASE("A Klipper upload error shows its reason instead of a Python traceback", "[PrintHost][Regression]")
+{
+    const std::string msg = format_error(k_busy_file_403, "", 403);
+    INFO("actual: " << msg);
+
+    CHECK(msg == "HTTP 403: Forbidden (File is loaded, upload not permitted)");
+    CHECK_THAT(msg, !Catch::Matchers::ContainsSubstring("Traceback"));
+    CHECK_THAT(msg, !Catch::Matchers::ContainsSubstring("file_manager.py"));
+}
+
+TEST_CASE("The specific cause is recovered from a file endpoint's traceback", "[PrintHost]")
+{
+    SECTION("a plain detail")
+    {
+        const std::string body = moonraker_error(403, "Forbidden", "File is loaded, upload not permitted");
+        CHECK(format_error(body, "", 403) == "HTTP 403: Forbidden (File is loaded, upload not permitted)");
+    }
+
+    SECTION("a detail whose own parentheses nest (a filename)")
+    {
+        const std::string detail = "Directory does not exist (/home/pi/gcodes/plate (1).gcode)";
+        const std::string body   = moonraker_error(400, "Bad Request", detail);
+        CHECK(format_error(body, "", 400) == "HTTP 400: Bad Request (" + detail + ")");
+    }
+
+    SECTION("a detail that contains the reason phrase")
+    {
+        const std::string body = moonraker_error(403, "Forbidden", "Forbidden zone: access denied");
+        CHECK(format_error(body, "", 403) == "HTTP 403: Forbidden (Forbidden zone: access denied)");
+    }
+
+    SECTION("a detail that spans lines")
+    {
+        const std::string detail = "Move out of range\nX=250.000 Y=10.000";
+        const std::string body   = moonraker_error(400, "Bad Request", detail);
+        CHECK(format_error(body, "", 400) == "HTTP 400: Bad Request (" + detail + ")");
+    }
+
+    SECTION("a detail that only repeats the reason phrase is dropped")
+    {
+        const std::string body = moonraker_error(401, "Unauthorized", "Unauthorized");
+        CHECK(format_error(body, "", 401) == "HTTP 401: Unauthorized");
+    }
+}
+
+TEST_CASE("An unhandled exception shows its type and message", "[PrintHost]")
+{
+    const std::string frame = "Traceback (most recent call last):\n"
+                              "  File \"/home/pi/moonraker/moonraker/components/file_manager/file_manager.py\", line 1, in write\n"
+                              "    self._write(data)\n";
+
+    SECTION("a one-line message")
+    {
+        const std::string body = envelope(500, "Internal Server Error", frame + "OSError: [Errno 28] No space left on device\n");
+        CHECK(format_error(body, "", 500) == "HTTP 500: Internal Server Error (OSError: [Errno 28] No space left on device)");
+    }
+
+    SECTION("a message that spans lines")
+    {
+        const std::string body = envelope(500, "Internal Server Error", frame + "ServerError: Klippy request failed\n  see klippy.log\n");
+        CHECK(format_error(body, "", 500) == "HTTP 500: Internal Server Error (ServerError: Klippy request failed\n  see klippy.log)");
+    }
+
+    SECTION("raised while handling an HTTPError with the same code")
+    {
+        const std::string traceback = frame + "tornado.web.HTTPError: HTTP 500: Internal Server Error (Database locked)\n\n"
+                                              "During handling of the above exception, another exception occurred:\n\n" +
+                                      frame + "OSError: [Errno 5] Input/output error\n";
+        const std::string body      = envelope(500, "Internal Server Error", traceback);
+        CHECK(format_error(body, "", 500) == "HTTP 500: Internal Server Error (OSError: [Errno 5] Input/output error)");
+    }
+
+    SECTION("a traceback with no header")
+    {
+        const std::string body = envelope(500, "Internal Server Error", "OSError: [Errno 5] Input/output error");
+        CHECK(format_error(body, "", 500) == "HTTP 500: Internal Server Error (OSError: [Errno 5] Input/output error)");
+    }
+}
+
+TEST_CASE("A reason already complete in message is shown unchanged", "[PrintHost]")
+{
+    SECTION("message is the whole reason, no trailing detail")
+    {
+        const std::string body = moonraker_error(503, "Klippy is not ready");
+        CHECK(format_error(body, "", 503) == "HTTP 503: Klippy is not ready");
+    }
+
+    SECTION("a message that itself contains parentheses is not duplicated")
+    {
+        const std::string reason = "Requested blocks (0-5) are unavailable";
+        const std::string body   = moonraker_error(400, reason);
+        CHECK(format_error(body, "", 400) == "HTTP 400: " + reason);
+    }
+}
+
+TEST_CASE("A Moonraker error with no usable detail shows just the reason phrase", "[PrintHost]")
+{
+    struct Case
+    {
+        const char* name;
+        const char* body;
+        unsigned status;
+        const char* expected;
+    };
+
+    const auto c = GENERATE(
+        Case{"an empty traceback", R"JSON({"error": {"code": 500, "message": "Internal Server Error", "traceback": ""}})JSON", 500,
+             "HTTP 500: Internal Server Error"},
+        Case{"a traceback of only whitespace", R"JSON({"error": {"code": 500, "message": "Internal Server Error", "traceback": "\n \n"}})JSON",
+             500, "HTTP 500: Internal Server Error"});
+
+    DYNAMIC_SECTION(c.name) { CHECK(format_error(c.body, "", c.status) == c.expected); }
+}
+
+TEST_CASE("A percent sign in the reason is not a format specifier", "[PrintHost]")
+{
+    const std::string body = moonraker_error(507, "Insufficient Storage", "disk 100% full");
+    CHECK(format_error(body, "", 507) == "HTTP 507: Insufficient Storage (disk 100% full)");
+}
+
+TEST_CASE("Error bodies that are not a Moonraker envelope are left unchanged", "[PrintHost]")
+{
+    SECTION("OctoPrint's string-valued error member")
+    {
+        const std::string body = R"JSON({"error": "File not found"})JSON";
+        CHECK(format_error(body, "", 404) == "HTTP 404: " + body);
+    }
+
+    SECTION("PrusaLink's top-level message, not under error")
+    {
+        const std::string body = R"JSON({"title": "Conflict", "message": "Printer is printing"})JSON";
+        CHECK(format_error(body, "", 409) == "HTTP 409: " + body);
+    }
+
+    SECTION("a body that is not JSON")
+    {
+        const std::string html = "<html><head><title>502 Bad Gateway</title></head></html>";
+        CHECK(format_error(html, "", 502) == "HTTP 502: " + html);
+    }
+
+    SECTION("an error object with no traceback")
+    {
+        const std::string body = R"JSON({"error": {"code": 500, "message": "Internal Server Error"}})JSON";
+        CHECK(format_error(body, "", 500) == "HTTP 500: " + body);
+    }
+
+    SECTION("an error object whose traceback is null")
+    {
+        const std::string body = R"JSON({"error": {"code": 500, "message": "Internal Server Error", "traceback": null}})JSON";
+        CHECK(format_error(body, "", 500) == "HTTP 500: " + body);
+    }
+
+    SECTION("an envelope whose reason phrase is empty")
+    {
+        const std::string body = envelope(403, "", "Traceback (most recent call last):\nOSError: denied\n");
+        CHECK(format_error(body, "", 403) == "HTTP 403: " + body);
+    }
+
+    SECTION("a transport error with no HTTP status")
+    {
+        CHECK(format_error("", "curl:Could not connect", 0) == "curl:Could not connect");
+    }
+}