Merge branch 'main' into feat/deps-mold-flag

* CLI: --inspect-paint — dump per-facet paint state as JSON

Reads the per-facet enforcer/blocker/extruder/fuzzy-skin state stored
on every ModelVolume (supported_facets / seam_facets /
mmu_segmentation_facets / fuzzy_skin_facets) and emits a structured
JSON summary to stdout. Machine-readable alternative to opening the
paint gizmos.

Per (object, volume, layer, state): facet count, surface area in
mm², and mesh-local bounding box. Empty layers collapse to
{"empty": true}. Summary at the top level rolls up totals.

One correctness detail worth calling out: FacetsAnnotation::
get_facets_strict returns an indexed_triangle_set whose `vertices`
array is the whole source mesh — only `indices` are filtered to the
painted triangles. A naive bounding_box(its) would report the whole
mesh's bbox even when only a few facets are painted. The helper
its_referenced_bbox() walks only the vertices actually indexed by
the painted triangles, so `bbox` correctly localizes the painted
region.

Rationale: every paint-driven workflow — GUI-painted .3mf verified
in CI, AI agents planning support enforcers, MMU color layout checks
— needs to know what's already painted on a model. Today that's a
GUI-only read. --inspect-paint closes that loop for scripted callers.

New file src/slic3r/Utils/PaintCLI.{hpp,cpp} (~215 lines). Depends
only on Model, TriangleMesh, TriangleSelector, FacetsAnnotation, and
nlohmann::json — all already in tree. No new dependencies, no
signature changes, no behavior change when the flag is absent.

Registered as an action (parallel to --info) so it satisfies the
"needs an action" check and bypasses the GUI fallback; control falls
through the normal post-action path to a clean exit 0.

Verification:
  unpainted STL:     every layer {"empty": true}, summary zero
  GUI-painted .3mf:  enforcer count / area / bbox match painter
  clean JSON:        parseable via jq

* CLI --inspect-paint: exit after printing, reject conflicting actions

- Finish like the end of CLI::run once the JSON is written, as the
  tooltip says. The callback manager is Linux-only, so its use is
  guarded.
- Reject actions that would otherwise be skipped without notice
  (--slice, --export-3mf, ...) before loading. Load-time options such as
  --uptodate are still accepted.
- Replace invalid UTF-8 in object names and paths instead of throwing.
- Report every input file as sources; inputs are merged into one model
  before actions run.

* CLI --inspect-paint: reject a run without input

Without an input file or --load-assemble-list there is nothing to
inspect, and the run printed nothing and exited 0. Reject it up front
with CLI_INVALID_PARAMS, next to the other invalid-parameter checks.

.github/workflows/build_orca.yml

@@ -85,6 +85,15 @@ jobs:
         shell: bash
         run: |
           leg="${{ runner.os }}-${{ inputs.arch || 'amd64' }}${{ runner.os == 'Windows' && format('-{0}', inputs.compiler) || '' }}"
+          # clang-cl refuses a precompiled header from another cl.exe build and ccache
+          # does not hash that build, so each one gets its own cache. The build number
+          # is read from cl.exe itself; the toolset directory keeps its name across patches.
+          if [ "${{ runner.os }}" = Windows ]; then
+            vswhere='/c/Program Files (x86)/Microsoft Visual Studio/Installer/vswhere.exe'
+            toolset=$(tr -d '\r\n' < "$("$vswhere" -latest -products '*' -find 'VC\Auxiliary\Build\Microsoft.VCToolsVersion.default.txt' | tr -d '\r')")
+            cl=$("$vswhere" -latest -products '*' -find 'VC\Tools\MSVC\'"$toolset"'\**\cl.exe' | tr -d '\r' | head -1)
+            leg="$leg-vc$("$cl" 2>&1 | grep -o -E 'Version [0-9.]+' | cut -d' ' -f2)"
+          fi
           echo "CCACHE_LEG=$leg" >> "$GITHUB_ENV"
           echo "CCACHE_ENTRY=ccache-$leg-${{ github.run_id }}-${{ github.run_attempt }}" >> "$GITHUB_ENV"
 

build_linux.sh

@@ -8,7 +8,7 @@ SCRIPT_PATH=$(dirname "$(readlink -f "${0}")")
 pushd "${SCRIPT_PATH}" > /dev/null
 
 function usage() {
-    echo "Usage: ./${SCRIPT_NAME} [-1][-b][-c][-d][-D][-e][-F][-g][-h][-i][-j N][-p][-r][-s][-t][-u][-l][-L]"
+    echo "Usage: ./${SCRIPT_NAME} [-1][-b][-c][-d][-D][-e][-F][-g][-h][-i][-j N][-p][-r][-s][-t][-u][-l][-L [lld|mold]]"
     echo "   -1: limit builds to one core (where possible)"
     echo "   -j N: limit builds to N cores (where possible)"
     echo "   -b: build in Debug mode"
@@ -27,7 +27,7 @@ function usage() {
     echo "   -t: build tests (optional), requires -s flag"
     echo "   -u: install system dependencies (asks for sudo password; build prerequisite)"
     echo "   -l: use Clang instead of GCC (default: GCC)"
-    echo "   -L: use ld.lld as linker (if available)"
+    echo "   -L [lld|mold]: use an alternate linker (if available) (default: lld)"
     echo "For a first use, you want to './${SCRIPT_NAME} -u'"
     echo "   and then './${SCRIPT_NAME} -dsi'"
     echo "For a GitHub Actions-like Linux build locally, use './${SCRIPT_NAME} -g -istrlL'"
@@ -115,8 +115,24 @@ while getopts ":1j:bcCdDeFghiprstulL" opt ; do
         FORWARDED_ARGS+=("-l")
         ;;
     L )
-        USE_LLD="1"
-        FORWARDED_ARGS+=("-L")
+        # -L takes an optional argument. getopts has no native support for
+        # this, so L is declared bare (no ':') in the optstring above, and we
+        # manually peek at the next unconsumed argv token via ${!OPTIND}. If
+        # it's a bare 'lld' or 'mold' (not another option, i.e. doesn't start
+        # with '-'), consume it as the explicit choice and advance OPTIND so
+        # getopts doesn't reprocess it as a new flag. Otherwise, leave it
+        # alone (it isn't meant for -L) and default to lld.
+        LINKER_NAME="lld"
+        next_arg="${!OPTIND-}"
+        if [[ -n "${next_arg}" ]] && [[ "${next_arg}" != -* ]] ; then
+            case "${next_arg}" in
+                lld|mold )
+                    LINKER_NAME="${next_arg}"
+                    OPTIND=$((OPTIND + 1))
+                    ;;
+            esac
+        fi
+        FORWARDED_ARGS+=("-L" "${LINKER_NAME}")
         ;;
     * )
 	echo "Unknown argument '${opt}', aborting."
@@ -130,11 +146,23 @@ if [ ${OPTIND} -eq 1 ] ; then
     exit 1
 fi
 
+shift $((OPTIND - 1))
+if [ $# -ne 0 ] ; then
+    echo "Unknown argument '$1', aborting."
+    exit 1
+fi
+
 if [[ -n "${CLEAN_DOCKER_IMAGE}" ]] && [[ -z "${USE_DOCKER}" ]] ; then
     echo "Error: -F requires -g."
     exit 1
 fi
 
+if [[ -n "${USE_DOCKER}" ]] && [[ "${LINKER_NAME}" == "mold" ]] ; then
+    echo "Error: -L mold is not available in the Docker/Podman build image, so -g and -L mold cannot be combined."
+    echo "Omit -L mold when using -g (the container build defaults to GCC without mold), or drop -g and build with -L mold directly on a host with mold installed."
+    exit 1
+fi
+
 function check_available_memory_and_disk() {
     FREE_MEM_GB=$(free --gibi --total | grep 'Mem' | rev | cut --delimiter=" " --fields=1 | rev)
     MIN_MEM_GB=10
@@ -492,14 +520,49 @@ if [[ -n "${USE_CLANG}" ]] ; then
     export CMAKE_C_CXX_COMPILER_CLANG=(-DCMAKE_C_COMPILER=/usr/bin/clang -DCMAKE_CXX_COMPILER=/usr/bin/clang++)
 fi
 
-# Configure use of ld.lld as the linker when requested
-export CMAKE_LLD_LINKER_ARGS=()
-if [[ -n "${USE_LLD}" ]] ; then
-    if command -v ld.lld >/dev/null 2>&1 ; then
-        LLD_BIN=$(command -v ld.lld)
-        export CMAKE_LLD_LINKER_ARGS=(-DCMAKE_LINKER="${LLD_BIN}" -DCMAKE_EXE_LINKER_FLAGS=-fuse-ld=lld -DCMAKE_SHARED_LINKER_FLAGS=-fuse-ld=lld -DCMAKE_MODULE_LINKER_FLAGS=-fuse-ld=lld)
+# Configure use of an alternate linker (-L lld or -L mold) when requested
+export CMAKE_LINKER_ARGS=()
+if [[ -n "${LINKER_NAME}" ]] ; then
+    case "${LINKER_NAME}" in
+        lld )
+            LINKER_BIN_NAME="ld.lld"
+            ;;
+        mold )
+            LINKER_BIN_NAME="mold"
+            # -fuse-ld=mold requires GCC 12.1+. Older GCC (e.g. GCC 11, shipped
+            # for Ubuntu 22.x via scripts/linux.d/debian) doesn't understand the
+            # flag, and cmake's compiler check then fails with a confusing
+            # generic "is not able to compile a simple test program" error
+            # instead of naming the real cause. Catch it here instead.
+            if [[ -z "${USE_CLANG}" ]] ; then
+                GCC_BIN="${CC:-gcc}"
+                if ! command -v "${GCC_BIN}" >/dev/null 2>&1 ; then
+                    GCC_BIN="cc"
+                fi
+                if command -v "${GCC_BIN}" >/dev/null 2>&1 ; then
+                    GCC_VERSION=$("${GCC_BIN}" -dumpfullversion 2>/dev/null)
+                    if [[ -n "${GCC_VERSION}" ]] && [[ "$(printf '%s\n%s\n' "${GCC_VERSION}" "12.1" | sort -V | head -n1)" != "12.1" ]] ; then
+                        echo "Error: -L mold requires GCC 12.1 or newer to support -fuse-ld=mold (found GCC ${GCC_VERSION} via '${GCC_BIN}')."
+                        echo "Use -l to build with Clang instead, upgrade your GCC toolchain, or omit -L mold."
+                        exit 1
+                    fi
+                fi
+            fi
+            ;;
+    esac
+
+    if command -v "${LINKER_BIN_NAME}" >/dev/null 2>&1 ; then
+        LINKER_BIN=$(command -v "${LINKER_BIN_NAME}")
+        export CMAKE_LINKER_ARGS=(-DCMAKE_LINKER="${LINKER_BIN}" "-DCMAKE_EXE_LINKER_FLAGS=-fuse-ld=${LINKER_NAME}" "-DCMAKE_SHARED_LINKER_FLAGS=-fuse-ld=${LINKER_NAME}" "-DCMAKE_MODULE_LINKER_FLAGS=-fuse-ld=${LINKER_NAME}")
     else
-        echo "Error: ld.lld not found. Please install the 'lld' package (e.g., sudo apt install lld) or omit -L."
+        case "${LINKER_NAME}" in
+            lld )
+                echo "Error: ld.lld not found. Please install the 'lld' package (e.g., sudo apt install lld) or omit -L lld."
+                ;;
+            mold )
+                echo "Error: mold not found. Please install the 'mold' package or omit -L mold."
+                ;;
+        esac
         exit 1
     fi
 fi
@@ -536,7 +599,7 @@ if [[ -n "${BUILD_DEPS}" ]] ; then
         BUILD_ARGS+=(-DCMAKE_BUILD_TYPE="${BUILD_CONFIG}")
     fi
 
-    print_and_run cmake -S deps -B deps/$BUILD_DIR "${CMAKE_C_CXX_COMPILER_CLANG[@]}" "${CMAKE_LLD_LINKER_ARGS[@]}" "${CMAKE_CCACHE_ARGS[@]}" -G Ninja "${COLORED_OUTPUT}" "${BUILD_ARGS[@]}"
+    print_and_run cmake -S deps -B deps/$BUILD_DIR "${CMAKE_C_CXX_COMPILER_CLANG[@]}" "${CMAKE_LINKER_ARGS[@]}" "${CMAKE_CCACHE_ARGS[@]}" -G Ninja "${COLORED_OUTPUT}" "${BUILD_ARGS[@]}"
     print_and_run cmake --build deps/$BUILD_DIR -j1
 fi
 
@@ -556,7 +619,7 @@ if [[ -n "${BUILD_ORCA}" ]] || [[ -n "${BUILD_TESTS}" ]] ; then
         BUILD_ARGS+=(-DORCA_UPDATER_SIG_KEY="${ORCA_UPDATER_SIG_KEY}")
     fi
 
-    print_and_run cmake -S . -B $BUILD_DIR "${CMAKE_C_CXX_COMPILER_CLANG[@]}" "${CMAKE_LLD_LINKER_ARGS[@]}" "${CMAKE_CCACHE_ARGS[@]}" -G "Ninja Multi-Config" \
+    print_and_run cmake -S . -B $BUILD_DIR "${CMAKE_C_CXX_COMPILER_CLANG[@]}" "${CMAKE_LINKER_ARGS[@]}" "${CMAKE_CCACHE_ARGS[@]}" -G "Ninja Multi-Config" \
 -DSLIC3R_PCH=${SLIC3R_PRECOMPILED_HEADERS} \
 -DORCA_TOOLS=ON \
 "${COLORED_OUTPUT}" \

deps/Boost/Boost.cmake

@@ -27,8 +27,15 @@ endif ()
 # Boost.Container's bundled dlmalloc passes int* where the Win32 Interlocked API
 # takes volatile long*; cl compiles that with a warning, clang errors out.
 set(_boost_c_flags_line "")
+set(_boost_cxx_flags_line "")
 if (MSVC AND CMAKE_C_COMPILER_ID STREQUAL "Clang")
     set(_boost_c_flags_line "-DCMAKE_C_FLAGS:STRING=-Wno-incompatible-pointer-types")
+    # The Visual Studio generator applies only the link language's flags to a
+    # project, and boost_container links as C++, so its C file never sees
+    # CMAKE_C_FLAGS. The C++ flags reach every file; keep CMake's defaults.
+    if (CMAKE_GENERATOR MATCHES "Visual Studio")
+        set(_boost_cxx_flags_line "-DCMAKE_CXX_FLAGS:STRING=${CMAKE_CXX_FLAGS} -Wno-incompatible-pointer-types")
+    endif ()
 endif ()
 
 orcaslicer_add_cmake_project(Boost
@@ -46,6 +53,7 @@ orcaslicer_add_cmake_project(Boost
         "${_context_arch_line}"
         "${_context_impl_line}"
         "${_boost_c_flags_line}"
+        "${_boost_cxx_flags_line}"
 )
 
 set(DEP_Boost_DEPENDS ZLIB)

deps/CMakeLists.txt

@@ -184,6 +184,11 @@ function(orcaslicer_add_cmake_project projectname)
 
     if (_dep_msvc_gen)
       set(_gen CMAKE_GENERATOR "${DEP_MSVC_GEN}" CMAKE_GENERATOR_PLATFORM "${DEP_PLATFORM}")
+      # The toolset picks the compiler here, not the CMAKE_<LANG>_COMPILER
+      # forwarded below, so without it a clang-cl superbuild builds with cl.
+      if (CMAKE_GENERATOR_TOOLSET)
+        list(APPEND _gen CMAKE_GENERATOR_TOOLSET "${CMAKE_GENERATOR_TOOLSET}")
+      endif ()
     else()
       set(_gen "")
     endif()

deps/Draco/Draco.cmake

@@ -7,4 +7,7 @@ orcaslicer_add_cmake_project(Draco
     ${_options}
     URL https://github.com/google/draco/archive/refs/tags/1.5.7.zip
     URL_HASH SHA256=27b72ba2d5ff3d0a9814ad40d4cb88f8dc89a35491c0866d952473f8f9416b77
+    CMAKE_ARGS
+        # The encoder and decoder tools duplicate draco.lib; see deps-windows.cmake.
+        "${DEP_LLD_FORCE_MULTIPLE}"
 )

deps/NLopt/NLopt.cmake

@@ -8,6 +8,8 @@ orcaslicer_add_cmake_project(NLopt
     -DNLOPT_GUILE:BOOL=OFF
     -DNLOPT_SWIG:BOOL=OFF
     -DNLOPT_TESTS:BOOL=OFF
+    # testopt is built regardless of NLOPT_TESTS; see deps-windows.cmake.
+    "${DEP_LLD_FORCE_MULTIPLE}"
 )
 
 if (MSVC)

deps/OpenSSL/OpenSSL.cmake

@@ -80,6 +80,12 @@ ExternalProject_Add(dep_OpenSSL
     INSTALL_COMMAND ${_install_cmd}
 )
 
+if (CMAKE_GENERATOR MATCHES "Visual Studio")
+    # OpenSSL builds with cl, but MSBuild runs nmake in this project's toolset
+    # environment, and ClangCL's puts clang's headers first. Use the default.
+    set_target_properties(dep_OpenSSL PROPERTIES VS_PLATFORM_TOOLSET "$(DefaultPlatformToolset)")
+endif ()
+
 ExternalProject_Add_Step(dep_OpenSSL install_cmake_files
     DEPENDEES install
 

deps/deps-windows.cmake

@@ -42,6 +42,15 @@ else ()
     message(FATAL_ERROR "Unsupported OS architecture: ${DEPS_ARCH}")
 endif ()
 
+# Draco's tools and NLopt's testopt compile sources that are also in their
+# static library. MSBuild passes the library before the objects and lld-link
+# resolves as it goes, so the library's copy wins and the object then reads as
+# a duplicate. Nothing uses those executables, so let lld keep the first one.
+set(DEP_LLD_FORCE_MULTIPLE "")
+if (CMAKE_GENERATOR MATCHES "Visual Studio" AND CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    set(DEP_LLD_FORCE_MULTIPLE "-DCMAKE_EXE_LINKER_FLAGS:STRING=${CMAKE_EXE_LINKER_FLAGS} /FORCE:MULTIPLE")
+endif ()
+
 if (${DEP_DEBUG})
     set(DEP_BOOST_DEBUG "debug")
 else ()

src/OrcaSlicer.cpp

@@ -87,6 +87,7 @@ using namespace nlohmann;
 #include "dev-utils/BaseException.h"
 #endif
 #include "slic3r/Utils/MeshInspect.hpp"
+#include "slic3r/Utils/PaintCLI.hpp"
 #include "slic3r/GUI/PartPlate.hpp"
 #include "slic3r/GUI/BitmapCache.hpp"
 #include "slic3r/GUI/OpenGLManager.hpp"
@@ -1443,6 +1444,29 @@ int CLI::run(int argc, char **argv)
         }
     }
 
+    // --inspect-paint prints its JSON and exits, so any action that does work of its
+    // own (slicing, exporting) would be skipped without notice. Reject those up front;
+    // only options that merely tune how the input is loaded may come along.
+    if (std::find(m_actions.begin(), m_actions.end(), "inspect_paint") != m_actions.end()) {
+        static const std::set<std::string> inspect_compatible = { "inspect_paint", "uptodate", "load_defaultfila", "min_save",
+                                                                  "mtcpp", "mstpp", "no_check", "normative_check", "pipe" };
+        for (const std::string &action : m_actions) {
+            if (inspect_compatible.count(action) == 0) {
+                std::string flag = action;
+                std::replace(flag.begin(), flag.end(), '_', '-');
+                boost::nowide::cerr << "--inspect-paint cannot be combined with --" << flag << std::endl;
+                record_exit_reson(outfile_dir, CLI_INVALID_PARAMS, 0, cli_errors[CLI_INVALID_PARAMS], sliced_info);
+                flush_and_exit(CLI_INVALID_PARAMS);
+            }
+        }
+        // Without input there is nothing to inspect; fail rather than print nothing and exit 0.
+        if (m_input_files.empty() && m_config.opt_string("load_assemble_list").empty()) {
+            boost::nowide::cerr << "--inspect-paint needs an input file or --load-assemble-list" << std::endl;
+            record_exit_reson(outfile_dir, CLI_INVALID_PARAMS, 0, cli_errors[CLI_INVALID_PARAMS], sliced_info);
+            flush_and_exit(CLI_INVALID_PARAMS);
+        }
+    }
+
     // --export-settings - writes its JSON to stdout, so reject every action or transform that may write there
     // too (--info, --help, --orient, slicing and exporting). The allowed ones do nothing when nothing is
     // sliced or exported.
@@ -6100,6 +6124,30 @@ int CLI::run(int argc, char **argv)
                 cli_status_callback(slicing_status);
             }
             g_cli_callback_mgr.stop();
+#endif
+            for (Model &m : m_models)
+                m.remove_backup_path_if_exist();
+            record_exit_reson(outfile_dir, CLI_SUCCESS, plate_to_slice, cli_errors[CLI_SUCCESS], sliced_info);
+            boost::nowide::cerr.flush();
+            return CLI_SUCCESS;
+        } else if (opt_key == "inspect_paint") {
+            // --inspect-paint — read the per-facet enforcer/blocker/extruder/
+            // fuzzy state from the loaded model and emit a JSON summary.
+            // Machine-readable alternative to opening the paint gizmos.
+            for (Model &model : m_models) {
+                model.add_default_instances();
+                Slic3r::PaintCLI::inspect_to_json(model, m_input_files, boost::nowide::cout);
+            }
+            boost::nowide::cout.flush();
+            // The tooltip promises "then exit"; conflicting actions were rejected before
+            // loading. Finish like the end of run(). flush_and_exit() is not usable here:
+            // it prints "found error ..." to stdout, which would corrupt the JSON.
+#if defined(__linux__) || defined(__LINUX__)
+            if (g_cli_callback_mgr.is_started()) {
+                PrintBase::SlicingStatus slicing_status{100, "All done, Success"};
+                cli_status_callback(slicing_status);
+            }
+            g_cli_callback_mgr.stop();
 #endif
             for (Model &m : m_models)
                 m.remove_backup_path_if_exist();

src/libslic3r/GCode/ToolOrdering.cpp

@@ -2735,6 +2735,28 @@ void ToolOrdering::enforce_mixed_component_order()
     }
 }
 
+// Declared in ToolOrdering.hpp (exposed for unit testing).
+std::vector<unsigned int> parse_cyclic_order(const std::string& str, unsigned int number_of_extruders)
+{
+    std::vector<unsigned int> order;
+    for (const std::string& token : split_string(str, ',')) {
+        try {
+            size_t pos      = 0;
+            int    filament = std::stoi(token, &pos); // stoi skips leading whitespace by itself
+            // stoi stops at the first non-digit, so "2x" would parse as 2. Require the whole token to be
+            // consumed (bar trailing whitespace) to drop it like any other garbage.
+            if (token.find_first_not_of(" \t\r\n", pos) != std::string::npos)
+                continue;
+            if (filament >= 1 && (unsigned int)filament <= number_of_extruders
+                && std::find(order.begin(), order.end(), (unsigned int)(filament - 1)) == order.end())
+                order.emplace_back((unsigned int)(filament - 1));
+        } catch (const std::exception&) {
+            // Not a number, ignore it.
+        }
+    }
+    return order;
+}
+
 void ToolOrdering::reorder_extruders_for_minimum_flush_volume(bool reorder_first_layer)
 {
     const PrintConfig* print_config = m_print_config_ptr;
@@ -2832,11 +2854,41 @@ void ToolOrdering::reorder_extruders_for_minimum_flush_volume(bool reorder_first
     const bool use_cyclic_ordering =
         (print_config->toolchange_ordering == ToolChangeOrderingType::Cyclic);
 
+    // By default the first layer keeps its adhesion-optimized order (and any custom first layer
+    // sequence); the cyclic sequence is only forced onto it when the user opts in.
+    const bool cyclic_first_layer = use_cyclic_ordering && print_config->toolchange_cyclic_first_layer.value;
+
+    // Optional user defined cyclic sequence, given as 1-based filament numbers ("3,2,1,4"). Filaments
+    // missing from it keep their ascending order after the listed ones, so a partial or bogus entry
+    // still yields the default cyclic order.
+    const std::vector<unsigned int> cyclic_order =
+        use_cyclic_ordering ? parse_cyclic_order(print_config->toolchange_cyclic_order.value, number_of_extruders)
+                            : std::vector<unsigned int>();
+
+    // Reorder a layer's filaments (0-based) for cyclic ordering: ascending by default, or following the
+    // user defined sequence when one was given. Filaments absent from the sequence keep ascending order
+    // after the listed ones.
+    auto apply_cyclic_order = [&cyclic_order](std::vector<unsigned int>& filaments) {
+        std::sort(filaments.begin(), filaments.end());
+        if (!cyclic_order.empty())
+            std::stable_sort(filaments.begin(), filaments.end(), [&cyclic_order](unsigned int lhs, unsigned int rhs) {
+                auto rank = [&cyclic_order](unsigned int filament) {
+                    return size_t(std::find(cyclic_order.begin(), cyclic_order.end(), filament) - cyclic_order.begin());
+                };
+                return rank(lhs) < rank(rhs);
+            });
+    };
+
     // other_layers_seq: the layer_idx and extruder_idx are base on 1
-    auto get_custom_seq = [&other_layers_seqs, &reorder_first_layer, &first_layer_filaments, &layer_filaments, use_cyclic_ordering](int layer_idx, std::vector<int>& out_seq) -> bool {
+    auto get_custom_seq = [&other_layers_seqs, &reorder_first_layer, &first_layer_filaments, &layer_filaments, use_cyclic_ordering, cyclic_first_layer, &apply_cyclic_order](int layer_idx, std::vector<int>& out_seq) -> bool {
         if (!reorder_first_layer && layer_idx == 0) {
-            out_seq.resize(first_layer_filaments.size());
-            std::transform(first_layer_filaments.begin(), first_layer_filaments.end(), out_seq.begin(), [](auto item) {return item + 1; });
+            // The first layer tool order is already decided (adhesion-optimized, plus any custom first
+            // layer sequence). Only override it with the cyclic sequence when the user opted in.
+            std::vector<unsigned int> ordered = first_layer_filaments;
+            if (cyclic_first_layer)
+                apply_cyclic_order(ordered);
+            out_seq.resize(ordered.size());
+            std::transform(ordered.begin(), ordered.end(), out_seq.begin(), [](auto item) {return int(item) + 1; });
             return true;
         }
         for (size_t idx = other_layers_seqs.size() - 1; idx != size_t(-1); --idx) {
@@ -2847,9 +2899,12 @@ void ToolOrdering::reorder_extruders_for_minimum_flush_volume(bool reorder_first
             }
         }
 
-        if (use_cyclic_ordering && layer_idx >= 0 && size_t(layer_idx) < layer_filaments.size()) {
+        // Skip the first layer here (layer_idx == 0 only reaches this point on the reorder_first_layer
+        // path) unless the user asked for cyclic order on it, so it keeps the default flush ordering.
+        if (use_cyclic_ordering && layer_idx >= 0 && (layer_idx != 0 || cyclic_first_layer)
+            && size_t(layer_idx) < layer_filaments.size()) {
             std::vector<unsigned int> ordered = layer_filaments[size_t(layer_idx)];
-            std::sort(ordered.begin(), ordered.end());
+            apply_cyclic_order(ordered);
             out_seq.resize(ordered.size());
             std::transform(ordered.begin(), ordered.end(), out_seq.begin(), [](auto item) { return int(item) + 1; });
             return true;

src/libslic3r/GCode/ToolOrdering.hpp

@@ -417,6 +417,11 @@ private:
     int                        most_used_extruder;
 };
 
+// Parse the user defined cyclic toolchange sequence ("3,2 , 1 , 4") into 0-based filament indices.
+// Out-of-range entries, duplicates and non-numeric tokens are dropped, so a partially valid string
+// still orders the filaments it does name. Exposed for unit testing.
+std::vector<unsigned int> parse_cyclic_order(const std::string& str, unsigned int number_of_extruders);
+
 } // namespace SLic3r
 
 #endif /* slic3r_ToolOrdering_hpp_ */

src/libslic3r/Preset.cpp

@@ -1320,6 +1320,8 @@ static std::vector<std::string> s_Preset_print_options{
     "wipe_tower_extra_flow",
     "single_extruder_multi_material_priming",
     "toolchange_ordering",
+    "toolchange_cyclic_order",
+    "toolchange_cyclic_first_layer",
     "wipe_tower_rotation_angle",
     "tree_support_branch_distance_organic",
     "tree_support_branch_diameter_organic",

src/libslic3r/Print.cpp

@@ -360,6 +360,8 @@ bool Print::invalidate_state_by_config_options(const ConfigOptionResolver & /* n
             || opt_key == "other_layers_print_sequence"
             || opt_key == "other_layers_print_sequence_nums" 
             || opt_key == "toolchange_ordering"
+            || opt_key == "toolchange_cyclic_order"
+            || opt_key == "toolchange_cyclic_first_layer"
             || opt_key == "extruder_ams_count"
             || opt_key == "extruder_nozzle_stats"
             || opt_key == "filament_map_mode"

src/libslic3r/PrintConfig.cpp

@@ -6700,6 +6700,34 @@ void PrintConfigDef::init_fff_params()
     def->enum_labels.emplace_back(L("Cyclic"));
     def->set_default_value(new ConfigOptionEnum<ToolChangeOrderingType>(ToolChangeOrderingType::Default));
 
+    def = this->add("toolchange_cyclic_order", coString);
+    def->label = L("Cyclic order");
+    def->category = L("Advanced");
+    def->tooltip = L(
+        "Custom filament sequence used by the cyclic toolchange ordering, as filament numbers separated by commas (e.g. \"3,2,1,4\").\n"
+        "Each layer prints its filaments following this sequence; filaments not listed are printed last, in ascending order.\n"
+        "Leave empty to cycle through the filaments in ascending order."
+    );
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionString(""));
+
+    def = this->add("toolchange_cyclic_first_layer", coBool);
+    def->label = L("Apply cyclic order to first layer");
+    def->category = L("Advanced");
+    def->tooltip = L(
+        "Applies the cyclic toolchange order to the first layer as well.\n"
+        "By default this is disabled, because the first layer is instead ordered for the best bed "
+        "adhesion: filaments that print small, fragile first-layer features are printed last, so the "
+        "following tool changes and travel moves are less likely to knock those weakly anchored parts "
+        "loose. This first-layer order also honors a custom first layer filament sequence when one is set. "
+        "The cyclic order's benefit (extra tool changes give each layer more time to cool) does not apply "
+        "to the first layer, which is printed slowly and hot for adhesion.\n"
+        "Enable this only if you need the exact same tool sequence on every layer, including the first, at "
+        "the cost of that adhesion optimization."
+    );
+    def->mode = comExpert;
+    def->set_default_value(new ConfigOptionBool(false));
+
     def = this->add("slice_closing_radius", coFloat);
     def->label = L("Slice gap closing radius");
     def->category = L("Quality");
@@ -11963,6 +11991,19 @@ CLIActionsConfigDef::CLIActionsConfigDef()
                      "the --ground-* options choose from. Machine-readable alternative to --info.");
     def->set_default_value(new ConfigOptionBool(false));
 
+    // --inspect-paint \u2014 dump the per-facet enforcer/blocker/extruder/fuzzy
+    // paint state stored on the loaded model (supports, seam, MMU color,
+    // fuzzy-skin) as JSON. Read-only; lets CI / scripted / AI tooling
+    // reason about existing paint on a .3mf without loading the GUI.
+    def = this->add("inspect_paint", coBool);
+    def->label = L("Inspect paint (JSON to stdout)");
+    def->tooltip = L("Print a structured JSON summary of every painted layer "
+                     "(supports, seam, MMU color, fuzzy-skin) already stored on "
+                     "the loaded model \u2014 per-state facet count, surface area, "
+                     "and mesh-local bounding box \u2014 then exit. Machine-readable "
+                     "alternative to opening the paint gizmos in the GUI.");
+    def->set_default_value(new ConfigOptionBool(false));
+
     def = this->add("export_settings", coString);
     def->label = L("Export Settings");
     def->tooltip = L("This exports settings to a file. Use - to write them to stdout.");

src/libslic3r/PrintConfig.hpp

@@ -1627,6 +1627,8 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionBool,                manual_filament_change))
     ((ConfigOptionBool,                single_extruder_multi_material_priming))
     ((ConfigOptionEnum<ToolChangeOrderingType>, toolchange_ordering))
+    ((ConfigOptionString,              toolchange_cyclic_order))
+    ((ConfigOptionBool,                toolchange_cyclic_first_layer))
     ((ConfigOptionBool,                wipe_tower_no_sparse_layers))
     ((ConfigOptionString,              change_filament_gcode))
     ((ConfigOptionString,              change_extrusion_role_gcode))

src/slic3r/CMakeLists.txt

@@ -682,6 +682,8 @@ set(SLIC3R_GUI_SOURCES
     Utils/Bonjour.hpp
     Utils/MeshInspect.cpp
     Utils/MeshInspect.hpp
+    Utils/PaintCLI.cpp
+    Utils/PaintCLI.hpp
     Utils/CalibUtils.cpp
     Utils/CalibUtils.hpp
     Utils/ColorSpaceConvert.cpp

src/slic3r/GUI/ConfigManipulation.cpp

@@ -1055,6 +1055,10 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig *config, in
 
     toggle_line("single_extruder_multi_material_priming", !bSEMM && have_prime_tower && supports_wipe_tower_2);
 
+    bool use_cyclic_ordering = config->opt_enum<ToolChangeOrderingType>("toolchange_ordering") == ToolChangeOrderingType::Cyclic;
+    toggle_line("toolchange_cyclic_order", use_cyclic_ordering);
+    toggle_line("toolchange_cyclic_first_layer", use_cyclic_ordering);
+
     toggle_line("prime_volume",have_prime_tower && (!purge_in_primetower || !bSEMM));
 
     for (auto el : {"flush_into_infill", "flush_into_support", "flush_into_objects"})

src/slic3r/GUI/Tab.cpp

@@ -3026,6 +3026,8 @@ void TabPrint::build()
         optgroup = page->new_optgroup(L("Advanced"), L"advanced");
         optgroup->append_single_option_line("interlocking_beam", "multimaterial_settings_advanced#interlocking-beam");
         optgroup->append_single_option_line("toolchange_ordering", "multimaterial_settings_advanced#toolchange-ordering");
+        optgroup->append_single_option_line("toolchange_cyclic_order", "multimaterial_settings_advanced#toolchange-order");
+        optgroup->append_single_option_line("toolchange_cyclic_first_layer", "multimaterial_settings_advanced#toolchange-order");
         optgroup->append_single_option_line("interface_shells", "multimaterial_settings_advanced#interface-shells");
         optgroup->append_single_option_line("mmu_segmented_region_max_width", "multimaterial_settings_advanced#maximum-width-of-segmented-region");
         optgroup->append_single_option_line("mmu_segmented_region_interlocking_depth", "multimaterial_settings_advanced#interlocking-depth-of-segmented-region");

src/slic3r/Utils/PaintCLI.cpp

@@ -0,0 +1,204 @@
+// PaintCLI.cpp — CLI paint-inspection primitives. See PaintCLI.hpp.
+#include "PaintCLI.hpp"
+
+#include "libslic3r/Model.hpp"
+#include "libslic3r/TriangleMesh.hpp"
+#include "libslic3r/TriangleSelector.hpp"
+
+#include <nlohmann/json.hpp>
+
+#include <cmath>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace Slic3r {
+namespace PaintCLI {
+
+namespace {
+
+using json = nlohmann::json;
+
+double its_surface_area(const indexed_triangle_set &its)
+{
+    double total = 0.0;
+    for (const stl_triangle_vertex_indices &t : its.indices) {
+        const Vec3f &a = its.vertices[t(0)];
+        const Vec3f &b = its.vertices[t(1)];
+        const Vec3f &c = its.vertices[t(2)];
+        total += 0.5 * (b - a).cross(c - a).norm();
+    }
+    return total;
+}
+
+// Bbox over triangle-referenced vertices only. get_facets_strict() returns
+// an itset with the full source vertex list — using bounding_box() on it
+// would report the whole mesh's bbox even when only a few facets are painted.
+BoundingBoxf3 its_referenced_bbox(const indexed_triangle_set &its)
+{
+    BoundingBoxf3 bb;
+    bool first = true;
+    for (const stl_triangle_vertex_indices &t : its.indices) {
+        for (int k = 0; k < 3; ++k) {
+            const Vec3d v = its.vertices[t(k)].cast<double>();
+            if (first) { bb.min = bb.max = v; first = false; }
+            else       bb.merge(v);
+        }
+    }
+    return bb;
+}
+
+json vec3_to_json(const Vec3d &v)
+{
+    return json::array({ v.x(), v.y(), v.z() });
+}
+
+json bbox_to_json(const BoundingBoxf3 &bb)
+{
+    return {
+        { "min",  vec3_to_json(bb.min) },
+        { "max",  vec3_to_json(bb.max) },
+        { "size", vec3_to_json(Vec3d(bb.max - bb.min)) },
+    };
+}
+
+// One (layer, state) row — empty ones are omitted at the caller level.
+json state_entry(const std::string &label, const indexed_triangle_set &its)
+{
+    return {
+        { "state",    label },
+        { "facets",   its.indices.size() },
+        { "area_mm2", its_surface_area(its) },
+        { "bbox",     bbox_to_json(its_referenced_bbox(its)) },
+    };
+}
+
+// Iterate the states relevant to one FacetsAnnotation kind, collecting
+// non-empty entries. Empty layer → {"empty": true}. `n_facets_out` is the
+// running total of painted facets — bumped for the summary.
+json inspect_layer(const ModelVolume &mv, const FacetsAnnotation &fa,
+                   const std::vector<std::pair<EnforcerBlockerType, std::string>> &states,
+                   size_t &n_facets_out)
+{
+    if (fa.empty())
+        return { { "empty", true } };
+
+    json entries = json::array();
+    for (const auto &st : states) {
+        if (!fa.has_facets(mv, st.first))
+            continue;
+        indexed_triangle_set its = fa.get_facets_strict(mv, st.first);
+        if (its.indices.empty())
+            continue;
+        n_facets_out += its.indices.size();
+        entries.push_back(state_entry(st.second, its));
+    }
+    return {
+        { "empty",  entries.empty() },
+        { "states", std::move(entries) },
+    };
+}
+
+const std::vector<std::pair<EnforcerBlockerType, std::string>> &supports_states()
+{
+    static const std::vector<std::pair<EnforcerBlockerType, std::string>> s = {
+        { EnforcerBlockerType::ENFORCER, "ENFORCER" },
+        { EnforcerBlockerType::BLOCKER,  "BLOCKER"  },
+    };
+    return s;
+}
+
+const std::vector<std::pair<EnforcerBlockerType, std::string>> &fuzzy_states()
+{
+    // FUZZY_SKIN is an enum alias for ENFORCER; the layer is single-state.
+    static const std::vector<std::pair<EnforcerBlockerType, std::string>> s = {
+        { EnforcerBlockerType::FUZZY_SKIN, "FUZZY_SKIN" },
+    };
+    return s;
+}
+
+const std::vector<std::pair<EnforcerBlockerType, std::string>> &mmu_states()
+{
+    static std::vector<std::pair<EnforcerBlockerType, std::string>> s = []{
+        std::vector<std::pair<EnforcerBlockerType, std::string>> v;
+        for (int i = 1; i <= int(EnforcerBlockerType::ExtruderMax); ++i)
+            v.emplace_back(EnforcerBlockerType(i), "extruder_" + std::to_string(i));
+        return v;
+    }();
+    return s;
+}
+
+} // namespace
+
+void inspect_to_json(const Model &model, const std::vector<std::string> &source_paths,
+                     std::ostream &out)
+{
+    json root;
+    root["sources"] = source_paths;
+    root["frame"]  = "mesh_local";
+    root["note"]   = "Coordinates are mesh-local (each volume's own frame). "
+                     "Paint gizmos operate in this frame.";
+
+    json objects = json::array();
+    size_t total_objects = 0, total_volumes = 0, total_painted = 0, total_facets = 0;
+
+    for (size_t oi = 0; oi < model.objects.size(); ++oi) {
+        const ModelObject *mo = model.objects[oi];
+        if (!mo) continue;
+        ++total_objects;
+
+        json obj;
+        obj["index"] = oi;
+        obj["name"]  = mo->name;
+
+        json volumes = json::array();
+        for (size_t vi = 0; vi < mo->volumes.size(); ++vi) {
+            const ModelVolume *mv = mo->volumes[vi];
+            if (!mv) continue;
+            ++total_volumes;
+
+            const indexed_triangle_set &its = mv->mesh().its;
+            json vol;
+            vol["index"]    = vi;
+            vol["name"]     = mv->name;
+            vol["n_facets"] = its.indices.size();
+            vol["is_model_part"] = mv->is_model_part();
+            vol["bbox_mesh_local"] = bbox_to_json(bounding_box(its));
+
+            size_t vol_painted = 0;
+            json paints;
+            paints["supports"]         = inspect_layer(*mv, mv->supported_facets,
+                                                      supports_states(),  vol_painted);
+            paints["seam"]             = inspect_layer(*mv, mv->seam_facets,
+                                                      supports_states(),  vol_painted);
+            paints["mmu_segmentation"] = inspect_layer(*mv, mv->mmu_segmentation_facets,
+                                                      mmu_states(),       vol_painted);
+            paints["fuzzy_skin"]       = inspect_layer(*mv, mv->fuzzy_skin_facets,
+                                                      fuzzy_states(),     vol_painted);
+            vol["paints"] = std::move(paints);
+            vol["painted_facets_total"] = vol_painted;
+
+            if (vol_painted > 0) ++total_painted;
+            total_facets += vol_painted;
+
+            volumes.push_back(std::move(vol));
+        }
+        obj["volumes"] = std::move(volumes);
+        objects.push_back(std::move(obj));
+    }
+    root["objects"] = std::move(objects);
+    root["summary"] = {
+        { "objects",                    total_objects },
+        { "volumes",                    total_volumes },
+        { "volumes_with_paint",         total_painted },
+        { "painted_facets_total",       total_facets  },
+    };
+
+    // Object names and file paths are arbitrary bytes, and dump() throws on invalid
+    // UTF-8 by default. Replace such sequences with U+FFFD so the output is always
+    // valid JSON rather than an exception out of the CLI.
+    out << root.dump(2, ' ', false, json::error_handler_t::replace) << std::endl;
+}
+
+} // namespace PaintCLI
+} // namespace Slic3r

src/slic3r/Utils/PaintCLI.hpp

@@ -0,0 +1,31 @@
+// PaintCLI.hpp — CLI paint-inspection primitives.
+//
+// Backs the --inspect-paint CLI action. Reads the per-facet enforcer /
+// blocker / extruder / fuzzy-skin state that OrcaSlicer stores on every
+// ModelVolume (supports, seam, MMU color, fuzzy-skin) and emits a
+// structured JSON summary — facet count, surface area, and mesh-local
+// bounding box per state — so CI / scripted / AI tooling can reason
+// about existing paint on a .3mf without opening the GUI.
+//
+// Coordinates are mesh-local (each volume's own frame), matching the
+// frame that the paint gizmos operate in.
+#ifndef slic3r_PaintCLI_hpp_
+#define slic3r_PaintCLI_hpp_
+
+#include <iosfwd>
+#include <string>
+#include <vector>
+
+namespace Slic3r {
+class Model;
+
+namespace PaintCLI {
+
+// `source_paths` lists every input file; the CLI merges them into one Model.
+void inspect_to_json(const Model &model, const std::vector<std::string> &source_paths,
+                     std::ostream &out);
+
+} // namespace PaintCLI
+} // namespace Slic3r
+
+#endif

tests/libslic3r/test_toolordering_nozzle_group.cpp

@@ -1025,3 +1025,41 @@ TEST_CASE("Selector slicing keeps the result valid across re-apply", "[Print][H2
     REQUIRE(status != PrintBase::APPLY_STATUS_INVALIDATED);
     REQUIRE(print.is_step_done(psSlicingFinished));
 }
+
+TEST_CASE("parse_cyclic_order parses user cyclic toolchange sequences", "[ToolOrdering][Cyclic]")
+{
+    // Filament numbers are 1-based in the UI; the parser returns 0-based indices.
+    SECTION("well-formed sequence") {
+        REQUIRE(parse_cyclic_order("3,2,1,4", 4) == std::vector<unsigned int>({2, 1, 0, 3}));
+    }
+
+    SECTION("surrounding whitespace is tolerated") {
+        REQUIRE(parse_cyclic_order(" 3 , 2 ,1, 4 ", 4) == std::vector<unsigned int>({2, 1, 0, 3}));
+    }
+
+    SECTION("out-of-range and non-positive entries are dropped") {
+        // 0 is below the 1-based range, 5 is above it for a 4-filament setup, -1 is invalid.
+        REQUIRE(parse_cyclic_order("0,5,-1,2", 4) == std::vector<unsigned int>({1}));
+    }
+
+    SECTION("duplicates keep only the first occurrence") {
+        REQUIRE(parse_cyclic_order("2,2,1,2", 4) == std::vector<unsigned int>({1, 0}));
+    }
+
+    SECTION("garbage tokens are ignored") {
+        REQUIRE(parse_cyclic_order("3,abc,,2,x1", 4) == std::vector<unsigned int>({2, 1}));
+    }
+
+    SECTION("tokens that only start with a number are ignored") {
+        // "2x" must be dropped rather than parsed as filament 2.
+        REQUIRE(parse_cyclic_order("3,2x,1", 4) == std::vector<unsigned int>({2, 0}));
+    }
+
+    SECTION("empty string yields an empty order") {
+        REQUIRE(parse_cyclic_order("", 4).empty());
+    }
+
+    SECTION("a partial sequence only names the filaments it lists") {
+        REQUIRE(parse_cyclic_order("3,1", 4) == std::vector<unsigned int>({2, 0}));
+    }
+}