BSDL: attach-bsdl command + persist the attached model

New `attach-bsdl <module> <part> <file.bsd>` command: parse via BsdlModel,
apply_bsdl() onto the part, store the path on Part::bsdl_path, report bound/
unbound. Persist a `B\t<path>` line under the part; on restore, re-parse and
re-apply each attached model (the .bsd path is persisted, not the derived
pin specs). Round-trip covered by test_bsdl_apply.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/system/parts.hpp

@@ -16,6 +16,7 @@ public:
     Module *prnt; ///< Pointer to the parent module.
     std::string connector_type; ///< Tag used by the transform registry; empty = untyped.
     ComponentKind kind; ///< Inferred from the part name's reference-designator prefix.
+    std::string bsdl_path; ///< Path to an attached BSDL (.bsd) model; "" if none. Re-applied on restore.
     void add(Pin *pin) override;
 };
 

src/system/persist.cpp

@@ -1,5 +1,6 @@
 #include "persist.hpp"
 
+#include "bsdl_model.hpp"
 #include "connect.hpp"
 #include "modules.hpp"
 #include "parts.hpp"
@@ -43,6 +44,8 @@ bool save_system(const System *sys, const std::string &filename, std::string &er
         for (auto &pkv : *mod) {
             Part *p = pkv.second;
             f << "P\t" << p->name << "\t" << p->connector_type << "\n";
+            if (!p->bsdl_path.empty())
+                f << "B\t" << p->bsdl_path << "\n";
             for (auto &nkv : *p) {
                 Pin *pin = nkv.second;
                 Signal *s = pin->signal();
@@ -161,6 +164,10 @@ System *restore_system(const std::string &filename, std::string &error)
                 Pin *pin1 = p1->get(fs[3]);
                 Pin *pin2 = p2->get(fs[6]);
                 cur_conn->pin_map.emplace_back(pin1, pin2);
+            } else if (tag == "B") {
+                if (!cur_part) return fail("B outside part");
+                if (fs.size() < 2) return fail("B needs <path>");
+                cur_part->bsdl_path = fs[1];
             } else {
                 return fail("unknown tag '" + tag + "'");
             }
@@ -169,5 +176,17 @@ System *restore_system(const std::string &filename, std::string &error)
         }
     }
 
+    // Re-derive BSDL-sourced pin specs from each attached model: we persisted the
+    // .bsd path (`B` tag), not the derived data, so re-parse and re-apply here.
+    // Models that no longer parse are skipped silently.
+    for (auto &mkv : *sys->modules()) {
+        for (auto &pkv : *mkv.second) {
+            Part *p = pkv.second;
+            if (p->bsdl_path.empty()) continue;
+            BsdlModel m = BsdlModel::from_file(p->bsdl_path);
+            if (m.valid()) apply_bsdl(p, m);
+        }
+    }
+
     return sys;
 }

src/tui/commands.cpp

@@ -8,6 +8,7 @@
 #include "system/parts.hpp"
 #include "system/persist.hpp"
 #include "system/pin_role.hpp"
+#include "system/bsdl_model.hpp"
 #include "system/pins.hpp"
 #include "system/signals.hpp"
 #include "system/system.hpp"
@@ -452,6 +453,57 @@ void Tui::RegisterCommands() {
         /*scriptable=*/ true,
         /*interactive=*/ true,
     };
+
+    commands["attach-bsdl"] = {
+        {{"module", Completion::None},
+         {"part (name or pattern)", Completion::None},
+         {"bsdl file (.bsd path)", Completion::None}},
+        [this](const std::vector<std::string> &args) {
+            if (!sys) { Print("no system: run 'new' first."); return; }
+            if (args.size() != 3) {
+                Print("usage: attach-bsdl <module> <part> <file.bsd>");
+                return;
+            }
+
+            Module *mod;
+            try { mod = sys->modules()->get(args[0]); }
+            catch (const std::exception &) {
+                Print("unknown module: " + args[0]); return;
+            }
+            Part *prt = nullptr;
+            try { prt = mod->get(args[1]); }
+            catch (const std::exception &) {
+                std::string needle = ToLower(args[1]);
+                std::vector<Part *> matches;
+                for (auto &p : *mod)
+                    if (ToLower(p.first).find(needle) != std::string::npos)
+                        matches.push_back(p.second);
+                if (matches.size() == 1) prt = matches[0];
+                else {
+                    Print(std::to_string(matches.size())
+                          + " match(es) for part '" + args[1] + "' in " + mod->name);
+                    return;
+                }
+            }
+
+            BsdlModel model = BsdlModel::from_file(args[2]);
+            if (!model.valid()) {
+                Print("attach-bsdl: cannot parse " + args[2]
+                      + (model.error().empty() ? "" : (": " + model.error())));
+                return;
+            }
+            BsdlApplyReport r = apply_bsdl(prt, model);
+            prt->bsdl_path = args[2];
+            Print(mod->name + "/" + prt->name + ": attached BSDL '" + model.entity()
+                  + "' — " + std::to_string(r.bound) + "/"
+                  + std::to_string((int)model.ports().size()) + " ports bound"
+                  + (r.unbound ? (", " + std::to_string(r.unbound) + " unbound") : ""));
+        },
+        /*prompt_for_missing=*/ false,
+        "attach a BSDL (.bsd) model to a part and populate pin specs",
+        /*scriptable=*/ true,
+        /*interactive=*/ false,
+    };
     commands["connect"] = {
         {{"module1", Completion::None},
          {"part1 (name or pattern)", Completion::None},