Load the CAD recipe from projects saved before it was renamed

The recipe's 3MF entry moved from Metadata/SnapOrca_cad.bin to
Metadata/orca_cad.bin, so projects saved by earlier builds opened with an
empty Design tab. Both 3MF backends now read either name and write only the
new one; the recipe version advances to 6 to mark the move.

src/libslic3r/CAD/CadDocument.cpp

@@ -3808,7 +3808,13 @@ bool CadDocument::deserialize_recipe(const std::string& blob)
                   + std::to_string(ORCA_CAD_RECIPE_VERSION) + ")";
             return false;
         }
-        if (v == 5) {
+        // The framed layout has been byte-identical since v5 (v6 advanced the stamp without
+        // touching the bytes), so every version from 5 up is read below. A future bump that DOES
+        // change the framing must exclude itself there — this is what forces that decision
+        // instead of letting a v7 blob be silently misread by the v5 reader.
+        static_assert(ORCA_CAD_RECIPE_VERSION <= 6,
+                      "recipe version bumped: confirm the new version still uses the v5 framing");
+        if (v >= 5) {
             // Framed path: every feature is a length-prefixed self-contained cereal stream, so
             // the same four lines handle BOTH directions of mismatch. Older file, newer build:
             // the sub-stream ends early, fa(f) throws, and the fields already assigned are kept

src/libslic3r/CAD/CadDocument.hpp

@@ -639,8 +639,10 @@ public:
     // v5: every feature is length-framed, so a reader can stop early on an older file and skip
     // the tail of a newer one. This is the LAST version that has to break anything — from here a
     // new field only needs appending to save/load, with no bump and no orphaned projects.
-    // v4 is still read, by the pre-framing flat path, so existing projects keep opening.
-    static constexpr uint32_t ORCA_CAD_RECIPE_VERSION = 5;
+    // v6: no wire-format change — the bytes are v5's, and both are read by the same framed path.
+    // The stamp advances only to put a project-container change on the record; the 3MF backends
+    // own that story. v4 still opens through the pre-framing flat path.
+    static constexpr uint32_t ORCA_CAD_RECIPE_VERSION = 6;
     std::string serialize_recipe() const;
     bool deserialize_recipe(const std::string& blob);
 

src/libslic3r/Format/3mf.cpp

@@ -74,6 +74,9 @@ const std::string PRINT_CONFIG_FILE = "Metadata/Slic3r_PE.config";
 const std::string MODEL_CONFIG_FILE = "Metadata/Slic3r_PE_model.config";
 const std::string LAYER_HEIGHTS_PROFILE_FILE = "Metadata/Slic3r_PE_layer_heights_profile.txt";
 const std::string CAD_RECIPE_FILE = "Metadata/orca_cad.bin";
+// Read-only: the recipe entry's pre-rename name. A reader that knows only the new one drops the
+// feature tree of every project written before the move, without a word. Never written.
+const std::string LEGACY_CAD_RECIPE_FILE = "Metadata/SnapOrca_cad.bin";
 const std::string LAYER_CONFIG_RANGES_FILE = "Metadata/Prusa_Slicer_layer_config_ranges.xml";
 const std::string SLA_SUPPORT_POINTS_FILE = "Metadata/Slic3r_PE_sla_support_points.txt";
 const std::string SLA_DRAIN_HOLES_FILE = "Metadata/Slic3r_PE_sla_drain_holes.txt";
@@ -806,7 +809,8 @@ ModelVolumeType type_from_string(const std::string &s)
                         return false;
                     }
                 }
-                if (boost::algorithm::iequals(name, CAD_RECIPE_FILE)) {
+                if (boost::algorithm::iequals(name, CAD_RECIPE_FILE)
+                 || boost::algorithm::iequals(name, LEGACY_CAD_RECIPE_FILE)) {
                     if (stat.m_uncomp_size > 0) {
                         std::string buffer((size_t)stat.m_uncomp_size, 0);
                         if (mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename,

src/libslic3r/Format/bbs_3mf.cpp

@@ -215,6 +215,9 @@ const std::string SLICE_INFO_CONFIG_FILE = "Metadata/slice_info.config";
 const std::string FILAMENT_SEQUENCE_FILE = "Metadata/filament_sequence.json";
 const std::string BBS_LAYER_HEIGHTS_PROFILE_FILE = "Metadata/layer_heights_profile.txt";
 const std::string ORCA_CAD_RECIPE_FILE = "Metadata/orca_cad.bin";
+// Read-only: the recipe entry's pre-rename name. A reader that knows only the new one drops the
+// feature tree of every project written before the move, without a word. Never written.
+const std::string LEGACY_CAD_RECIPE_FILE = "Metadata/SnapOrca_cad.bin";
 const std::string LAYER_CONFIG_RANGES_FILE = "Metadata/layer_config_ranges.xml";
 const std::string BRIM_EAR_POINTS_FILE = "Metadata/brim_ear_points.txt";
 /*const std::string SLA_SUPPORT_POINTS_FILE = "Metadata/Slic3r_PE_sla_support_points.txt";
@@ -1971,7 +1974,8 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
                     // extract slic3r print config file
                     _extract_project_config_from_archive(archive, stat, config, config_substitutions, model);
                 }
-                else if (boost::algorithm::iequals(name, ORCA_CAD_RECIPE_FILE)) {
+                else if (boost::algorithm::iequals(name, ORCA_CAD_RECIPE_FILE)
+                      || boost::algorithm::iequals(name, LEGACY_CAD_RECIPE_FILE)) {
                     // Restore the editable CAD recipe (optional; absent in non-CAD projects).
                     if (stat.m_uncomp_size > 0) {
                         std::string buf((size_t)stat.m_uncomp_size, '\0');