feat: firmware-agnostic per-tool PA emission for IMEX parallel modes

Extends set_pressure_advance() with an optional tool index (default -1,
preserving existing behavior for all non-IMEX call sites). Per-firmware:
- Klipper: EXTRUDER=extruder[N] when tool >= 0, bare command otherwise
- RRF: M572 D<N> when tool >= 0, bare M572 otherwise (no D0 fallback)
- Marlin 2: M900 K<X> T<N> when tool >= 0, bare M900 otherwise
- Marlin Legacy / fallback: M900 K<X> always

Adds m_imex_parallel_mode to GCode, set once per export from the active
plate mode. PA and layer-transition temperature tool-qualification are
gated on this being a non-primary parallel mode — primary mode prints
use regular tool-change PA exactly like any non-IMEX printer. Secondary
active tools in parallel modes receive explicit per-tool PA at print
start since they never go through a tool-change sequence.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/libslic3r/GCode.cpp

@@ -3094,9 +3094,11 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
     std::string imex_active_mode;
     int         imex_active_mode_index = 0;
     std::string imex_active_mode_gcode;
+    m_imex_parallel_mode.clear();
     if (print.config().is_imex.value && !print.objects().empty()) {
         const std::string& raw = print.objects().front()->config().imex_parallel_mode.value;
         imex_active_mode = raw.empty() ? "primary" : raw;
+        m_imex_parallel_mode = imex_active_mode;
         const auto& mode_names  = print.config().imex_mode_names.values;
         const auto& mode_gcodes = print.config().imex_mode_gcodes.values;
         for (size_t i = 0; i < mode_names.size(); ++i) {
@@ -3161,13 +3163,6 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
             // mark the first filament used in print
             file.write_format(";VT%d\n", initial_extruder_id);
         }
-        // Orca: add missing PA settings for initial filament
-        if (m_config.enable_pressure_advance.get_at(initial_non_support_extruder_id)) {
-            file.write(m_writer.set_pressure_advance(m_config.pressure_advance.get_at(initial_non_support_extruder_id)));
-            // Orca: Adaptive PA
-            // Reset Adaptive PA processor last PA value
-            m_pa_processor->resetPreviousPA(m_config.pressure_advance.get_at(initial_non_support_extruder_id));
-        }
     }
 
     //flush FanMover buffer to avoid modifying the start gcode if it's manual.
@@ -3227,6 +3222,19 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
         // Set initial extruder only after custom start G-code.
         // Ugly hack: Do not set the initial extruder if the extruder is primed using the MMU priming towers at the edge of the print bed.
         file.write(this->set_extruder(initial_extruder_id, 0.));
+
+        // IMEX parallel modes only: emit PA for all secondary active tools.
+        // In primary mode, regular tool-change PA handles each tool as it becomes active.
+        // In parallel modes no tool changes occur, so every carriage must be addressed
+        // explicitly here before printing starts.
+        if (!m_imex_parallel_mode.empty() && m_imex_parallel_mode != "primary") {
+            for (int tool_idx : get_imex_active_tools(print)) {
+                if (tool_idx == (int)initial_extruder_id) continue;
+                if (!print.config().enable_pressure_advance.get_at(tool_idx)) continue;
+                file.write(m_writer.set_pressure_advance(
+                    print.config().pressure_advance.get_at(tool_idx), tool_idx));
+            }
+        }
     }
     // BBS: set that indicates objs with brim
     for (auto iter = print.m_brimMap.begin(); iter != print.m_brimMap.end(); ++iter) {
@@ -4678,7 +4686,8 @@ LayerResult GCode::process_layer(
         // IMEX parallel modes: secondary carriages (T1-T3) never receive tool-change commands,
         // so they're not in m_writer.extruders() and multiple_extruders==false (max id==0).
         // Use the static set_temperature path for IMEX so the T index is always emitted.
-        if (print.config().is_imex.value) {
+        // In primary mode, fall through to the standard path — tool changes handle temps normally.
+        if (!m_imex_parallel_mode.empty() && m_imex_parallel_mode != "primary") {
             // All active tools need explicit temps — none receive tool-change commands,
             // so we can't rely on the condition used for non-IMEX (temp != initial_layer_temp).
             // A tool whose initial and regular temps are the same still needs to be set here.
@@ -7550,7 +7559,12 @@ std::string GCode::set_extruder(unsigned int new_filament_id, double print_z, bo
         }
         
         if (m_config.enable_pressure_advance.get_at(new_filament_id)) {
-            gcode += m_writer.set_pressure_advance(m_config.pressure_advance.get_at(new_filament_id));
+            // In IMEX parallel modes each carriage needs an explicit tool address.
+            // In primary mode (single active tool) regular tool changes handle PA
+            // so no qualifier is needed — same as a non-IMEX printer.
+            const bool imex_parallel = !m_imex_parallel_mode.empty() && m_imex_parallel_mode != "primary";
+            const int pa_tool = imex_parallel ? (int)new_filament_id : -1;
+            gcode += m_writer.set_pressure_advance(m_config.pressure_advance.get_at(new_filament_id), pa_tool);
             // Orca: Adaptive PA
             // Reset Adaptive PA processor last PA value
             m_pa_processor->resetPreviousPA(m_config.pressure_advance.get_at(new_filament_id));
@@ -7849,7 +7863,9 @@ std::string GCode::set_extruder(unsigned int new_filament_id, double print_z, bo
         gcode += m_ooze_prevention.post_toolchange(*this);
 
     if (m_config.enable_pressure_advance.get_at(new_filament_id)) {
-        gcode += m_writer.set_pressure_advance(m_config.pressure_advance.get_at(new_filament_id));
+        const bool imex_parallel = !m_imex_parallel_mode.empty() && m_imex_parallel_mode != "primary";
+        const int pa_tool = imex_parallel ? (int)new_filament_id : -1;
+        gcode += m_writer.set_pressure_advance(m_config.pressure_advance.get_at(new_filament_id), pa_tool);
         // Orca: Adaptive PA
         // Reset Adaptive PA processor last PA value
         m_pa_processor->resetPreviousPA(m_config.pressure_advance.get_at(new_filament_id));

src/libslic3r/GCode.hpp

@@ -592,6 +592,11 @@ private:
     
     std::unique_ptr<AdaptivePAProcessor>      m_pa_processor;
 
+    // IMEX: active parallel mode name ("primary", "copy", "iq-copy", etc.).
+    // Set at the start of export. Empty string means non-IMEX or not yet set.
+    // PA and temperature tool-qualification is only applied when this is not "primary".
+    std::string m_imex_parallel_mode;
+
     std::unique_ptr<WipeTowerIntegration> m_wipe_tower;
 
     std::unique_ptr<SmallAreaInfillFlowCompensator> m_small_area_infill_flow_compensator;

src/libslic3r/GCodeWriter.cpp

@@ -351,22 +351,39 @@ std::string GCodeWriter::set_junction_deviation(double junction_deviation){
     return gcode.str();
 }
 
-std::string GCodeWriter::set_pressure_advance(double pa) const
+std::string GCodeWriter::set_pressure_advance(double pa, int tool) const
 {
     std::ostringstream gcode;
     if (pa < 0)
         return gcode.str();
-    if(m_is_bbl_printers){
+    if (m_is_bbl_printers) {
-        //SoftFever: set L1000 to use linear model
+        // SoftFever: set L1000 to use linear model
-        gcode << "M900 K" <<std::setprecision(4)<< pa << " L1000 M10 ; Override pressure advance value\n";
+        gcode << "M900 K" << std::setprecision(4) << pa << " L1000 M10 ; Override pressure advance value\n";
-    }
+    } else if (FLAVOR_IS(gcfKlipper)) {
-    else{
+        // Klipper routes PA by extruder name, not active tool.
-        if (FLAVOR_IS(gcfKlipper))
+        // Convention: first extruder is "extruder", subsequent are "extruder1", "extruder2", etc.
-            gcode << "SET_PRESSURE_ADVANCE ADVANCE=" << std::setprecision(4) << pa << "; Override pressure advance value\n";
+        gcode << "SET_PRESSURE_ADVANCE ADVANCE=" << std::setprecision(4) << pa;
-        else if(FLAVOR_IS(gcfRepRapFirmware))
+        if (tool > 0)
-            gcode << ("M572 D0 S") << std::setprecision(4) << pa << "; Override pressure advance value\n";
+            gcode << " EXTRUDER=extruder" << tool;
-        else
+        else if (tool == 0)
-            gcode << "M900 K" <<std::setprecision(4)<< pa << "; Override pressure advance value\n";
+            gcode << " EXTRUDER=extruder";
+        gcode << " ; Override pressure advance value\n";
+    } else if (FLAVOR_IS(gcfRepRapFirmware)) {
+        // RRF: M572 without D applies to the current tool; with D targets a specific extruder.
+        // Use D only when an explicit tool index is provided (IMEX parallel modes).
+        gcode << "M572";
+        if (tool >= 0)
+            gcode << " D" << tool;
+        gcode << " S" << std::setprecision(4) << pa << " ; Override pressure advance value\n";
+    } else if (FLAVOR_IS(gcfMarlinFirmware)) {
+        // Marlin 2.x supports T parameter for per-extruder LA
+        gcode << "M900 K" << std::setprecision(4) << pa;
+        if (tool >= 0)
+            gcode << " T" << tool;
+        gcode << " ; Override pressure advance value\n";
+    } else {
+        // Marlin Legacy and everything else: single-extruder M900, no tool parameter
+        gcode << "M900 K" << std::setprecision(4) << pa << " ; Override pressure advance value\n";
     }
     return gcode.str();
 }

src/libslic3r/GCodeWriter.hpp

@@ -57,7 +57,7 @@ public:
     // Orca: set acceleration and jerk in one command for Klipper
     std::string set_accel_and_jerk(unsigned int acceleration, double jerk);
     std::string set_junction_deviation(double junction_deviation); 
-    std::string set_pressure_advance(double pa) const;
+    std::string set_pressure_advance(double pa, int tool = -1) const;
     std::string set_input_shaping(char axis, float damp, float freq, std::string type) const;
     std::string reset_e(bool force = false);
     std::string update_progress(unsigned int num, unsigned int tot, bool allow_100 = false) const;