fix: port BBS NozzleStatusRecorder pattern for per-carousel-slot purge tracking

The upstream _make_wipe_tower() tracked purge volumes per-extruder (2 slots),
which collapsed all H2C carousel filaments into one slot and caused massive
redundant AMS flushing (~40g instead of ~0.4g).

Changes:
- Print.cpp: Replace per-extruder nozzle_cur_filament_ids with BBS
  NozzleStatusRecorder that tracks per group_id (carousel slot 0..6).
  Use get_nozzle_for_filament() to resolve physical slot per layer.
  Select filament_prime_volume_nc for nozzle changes, filament_prime_volume
  for filament changes (BBS pattern).
- PrintConfig.hpp/cpp: Register filament_prime_volume (per-filament EC prime
  volume, default 45mm³) matching BBS PrintConfig.
- Preset.cpp: Add filament_prime_volume to preset keys list.

Safe for non-carousel printers: group_id == extruder_id when each extruder
has one nozzle, so NozzleStatusRecorder behaves identically to the original
per-extruder tracking.

Reference to BBS: BambuStudio/src/libslic3r/Print.cpp _make_wipe_tower() L3341-3392

src/libslic3r/Preset.cpp

@@ -1372,7 +1372,7 @@ static std::vector<std::string> s_Preset_filament_options {/*"filament_colour",
     "filament_ramming_travel_time", "filament_ramming_travel_time_nc",
     "filament_pre_cooling_temperature", "filament_pre_cooling_temperature_nc",
     "filament_preheat_temperature_delta", "filament_retract_length_nc",
-    "filament_change_length_nc", "filament_prime_volume_nc",
+    "filament_change_length_nc", "filament_prime_volume", "filament_prime_volume_nc",
     "long_retractions_when_ec", "retraction_distances_when_ec",
     //ams chamber
     "filament_dev_ams_drying_ams_limitations", "filament_dev_ams_drying_temperature", "filament_dev_ams_drying_time", "filament_dev_ams_drying_heat_distortion_temperature",

src/libslic3r/Print.cpp

@@ -3975,14 +3975,27 @@ void Print::_make_wipe_tower()
             multi_extruder_flush.emplace_back(wipe_volumes);
         }
 
-        std::vector<int>filament_maps = get_filament_maps();
+        // Reference to BBS: BambuStudio/src/libslic3r/Print.cpp _make_wipe_tower()
+        // Use NozzleStatusRecorder for per-carousel-slot tracking (BBS pattern).
+        // The original Orca code tracked per-extruder (2 slots), which collapsed all
+        // carousel filaments into one slot and caused massive redundant AMS flushing.
+        auto group_result = get_layered_nozzle_group_result();
+        MultiNozzleUtils::NozzleStatusRecorder nozzle_recorder;
+
+        std::vector<int>filament_maps = get_filament_maps();
+        int layer_idx = -1;
 
-        std::vector<unsigned int> nozzle_cur_filament_ids(nozzle_nums, -1);
         unsigned int current_filament_id = m_wipe_tower_data.tool_ordering.first_extruder();
-        size_t cur_nozzle_id = filament_maps[current_filament_id] - 1;
+        // Initialize NozzleStatusRecorder with the first filament's carousel slot
-        nozzle_cur_filament_ids[cur_nozzle_id] = current_filament_id;
+        if (group_result) {
+            auto nozzle = group_result->get_nozzle_for_filament(current_filament_id, layer_idx);
+            if (nozzle)
+                nozzle_recorder.set_nozzle_status(nozzle->group_id, current_filament_id, nozzle->extruder_id);
+        }
 
         for (auto& layer_tools : m_wipe_tower_data.tool_ordering.layer_tools()) { // for all layers
+            ++layer_idx;
+
             if (!layer_tools.has_wipe_tower) continue;
             bool first_layer = &layer_tools == &m_wipe_tower_data.tool_ordering.front();
             wipe_tower.plan_toolchange((float)layer_tools.print_z, (float)layer_tools.wipe_tower_layer_height, current_filament_id, current_filament_id);
@@ -3993,30 +4006,73 @@ void Print::_make_wipe_tower()
                 if (filament_id == current_filament_id)
                     continue;
 
-                int          nozzle_id = filament_maps[filament_id] - 1;
-                unsigned int pre_filament_id = nozzle_cur_filament_ids[nozzle_id];
-
                 float volume_to_purge = 0;
-                if (pre_filament_id != (unsigned int)(-1) && pre_filament_id != filament_id) {
+
-                    volume_to_purge = multi_extruder_flush[nozzle_id][pre_filament_id][filament_id];
+                // Reference to BBS: BambuStudio/src/libslic3r/Print.cpp L3361-3392
-                    // Fast purge mode uses flush_multiplier_fast; Default is inert.
+                // Per-carousel-slot purge tracking via NozzleStatusRecorder
-                    float flush_multiplier = (m_config.prime_volume_mode == PrimeVolumeMode::pvmFast) ? m_config.flush_multiplier_fast.get_at(nozzle_id)
+                if (group_result) {
-                                                                                                      : m_config.flush_multiplier.get_at(nozzle_id);
+                    auto nozzle_info = group_result->get_nozzle_for_filament(filament_id, layer_idx);
+                    if (nozzle_info) {
+                        int extruder_id = nozzle_info->extruder_id;
+                        int nozzle_id   = nozzle_info->group_id;
+                        int prev_nozzle_filament = nozzle_recorder.get_filament_in_nozzle(nozzle_id);
+
+                        if (!nozzle_recorder.is_nozzle_empty(nozzle_id) &&
+                            static_cast<int>(filament_id) != prev_nozzle_filament) {
+                            volume_to_purge = multi_extruder_flush[extruder_id][prev_nozzle_filament][filament_id];
+                            // Fast purge mode uses flush_multiplier_fast; Default is inert.
+                            float flush_multiplier = (m_config.prime_volume_mode == PrimeVolumeMode::pvmFast)
+                                ? m_config.flush_multiplier_fast.get_at(extruder_id)
+                                : m_config.flush_multiplier.get_at(extruder_id);
+                            volume_to_purge *= flush_multiplier;
+                            volume_to_purge = layer_tools.wiping_extrusions().mark_wiping_extrusions(
+                                *this, current_filament_id, filament_id, volume_to_purge);
+                        }
+                        nozzle_recorder.set_nozzle_status(nozzle_id, filament_id, extruder_id);
+                    }
+                } else {
+                    // Fallback: original Orca per-extruder path (non-carousel printers)
+                    int nozzle_id = filament_maps[filament_id] - 1;
+                    volume_to_purge = multi_extruder_flush[nozzle_id][current_filament_id][filament_id];
+                    float flush_multiplier = (m_config.prime_volume_mode == PrimeVolumeMode::pvmFast)
+                        ? m_config.flush_multiplier_fast.get_at(nozzle_id)
+                        : m_config.flush_multiplier.get_at(nozzle_id);
                     volume_to_purge *= flush_multiplier;
-                    volume_to_purge = pre_filament_id == -1 ? 0 :
+                    volume_to_purge = layer_tools.wiping_extrusions().mark_wiping_extrusions(
-                        layer_tools.wiping_extrusions().mark_wiping_extrusions(*this, current_filament_id, filament_id, volume_to_purge);
+                        *this, current_filament_id, filament_id, volume_to_purge);
                 }
 
                 //During the filament change, the extruder will extrude an extra length of grab_length for the corresponding detection, so the purge can reduce this length.
-                float grab_purge_volume = m_config.grab_length.get_at(nozzle_id) * 2.4; //(diameter/2)^2*PI=2.4
+                int grab_extruder_id = filament_maps[filament_id] - 1;
+                float grab_purge_volume = m_config.grab_length.get_at(grab_extruder_id) * 2.4; //(diameter/2)^2*PI=2.4
                 volume_to_purge = std::max(0.f, volume_to_purge - grab_purge_volume);
 
-                // Saving mode reduces the prime volume to 15 mm3; Default is inert.
+                // Reference to BBS: BambuStudio/src/libslic3r/Print.cpp L3381-3387
-                float prime_volume = (m_config.prime_volume_mode == PrimeVolumeMode::pvmSaving) ? 15.f : (float) m_config.prime_volume;
+                // Select prime volume per-filament: nozzle change (carousel rotation) uses
+                // filament_prime_volume_nc, filament change (same nozzle slot) uses filament_prime_volume.
+                // BBS passes both to plan_toolchange (7 args), we select the right one here (6 args).
+                float wipe_volume_ec = filament_id < m_config.filament_prime_volume.values.size()
+                    ? m_config.filament_prime_volume.values[filament_id]
+                    : (float) m_config.prime_volume;
+                float wipe_volume_nc = filament_id < m_config.filament_prime_volume_nc.values.size()
+                    ? m_config.filament_prime_volume_nc.values[filament_id]
+                    : (float) m_config.prime_volume;
+
+                float prime_volume = wipe_volume_ec;
+                if (group_result) {
+                    bool is_nozzle_change = group_result->are_filaments_same_extruder(current_filament_id, filament_id, layer_idx) &&
+                                           !group_result->are_filaments_same_nozzle(current_filament_id, filament_id, layer_idx);
+                    if (is_nozzle_change) {
+                        prime_volume = wipe_volume_nc;
+                    }
+                }
+                if (m_config.prime_volume_mode == PrimeVolumeMode::pvmSaving) {
+                    prime_volume = 15.f;
+                }
+
                 wipe_tower.plan_toolchange((float)layer_tools.print_z, (float)layer_tools.wipe_tower_layer_height, current_filament_id, filament_id,
                     prime_volume, volume_to_purge);
                 current_filament_id = filament_id;
-                nozzle_cur_filament_ids[nozzle_id] = filament_id;
             }
             layer_tools.wiping_extrusions().ensure_perimeters_infills_order(*this);
 

src/libslic3r/PrintConfig.cpp

@@ -7995,6 +7995,15 @@ void PrintConfigDef::init_fff_params()
     def->mode = comDevelop;
     def->set_default_value(new ConfigOptionBool(false));
 
+    // Reference to BBS: BambuStudio/src/libslic3r/PrintConfig.cpp L2617-2624
+    def           = this->add("filament_prime_volume", coFloats);
+    def->label    = L("Filament change");
+    def->tooltip  = L("The volume of material required to prime the extruder on the tower, excluding a hotend change.");
+    def->sidetext = L("mm³");
+    def->min      = 1.0;
+    def->mode     = comSimple;
+    def->set_default_value(new ConfigOptionFloats{45.});
+
     def           = this->add("filament_prime_volume_nc", coFloats);
     def->label    = L("Hotend change");
     def->tooltip  = L("The volume of material required to prime the extruder for a hotend change on the tower.");

src/libslic3r/PrintConfig.hpp

@@ -1837,6 +1837,8 @@ PRINT_CONFIG_CLASS_DERIVED_DEFINE(
     // BBS: wipe tower is only used for priming
     ((ConfigOptionFloat,              prime_volume))
     // Nozzle-change (nc) prime volume + pre-heat delta
+    // Reference to BBS: BambuStudio/src/libslic3r/PrintConfig.hpp L1524-1525
+    ((ConfigOptionFloats,             filament_prime_volume))
     ((ConfigOptionFloats,             filament_prime_volume_nc))
     ((ConfigOptionFloatsNullable,     filament_preheat_temperature_delta))
     ((ConfigOptionFloats,             flush_multiplier))