build: split core/ from frontends/; prepare for multiple GUI/TUI targets

Reorganise the tree into business vs frontend as separate directories:
  src/core/{domain,imports,app}   (was system/, imports/, app/)
  src/frontends/tui/              (was tui/ + main.cpp)
  tests/tui/                      (the FTXUI-coupled helper test)
All cross-dir #include paths rewritten; same-dir includes untouched.

CMake: essim_core is the frontend-agnostic business library — links libzip,
pugixml and bsdl, NO GUI toolkit. Each frontend is a self-contained
src/frontends/<name>/ (own CMakeLists, toolkit, main.cpp) that links
essim_core, selected with -DESSIM_FRONTEND=<name> (default tui; 'none' = core +
tests only, no toolkit fetched). FTXUI moved into the tui frontend. Tests are
split: essim_tests links essim_core (no FTXUI), essim_tui_tests links essim_tui.

Verified: default tui build green (ctest 2/2); ESSIM_FRONTEND=none builds the
core + tests with FTXUI never fetched and no `essim` binary.

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

CMakeLists.txt

@@ -11,49 +11,54 @@ project(essim
 
 include(FetchContent)
 
-set(FTXUI_BUILD_DOCS OFF CACHE INTERNAL "")
-set(FTXUI_BUILD_EXAMPLES OFF CACHE INTERNAL "")
-set(FTXUI_BUILD_TESTS OFF CACHE INTERNAL "")
-set(FTXUI_ENABLE_INSTALL OFF CACHE INTERNAL "")
-
-FetchContent_Declare(ftxui
-  GIT_REPOSITORY https://github.com/ArthurSonzogni/FTXUI.git
-  GIT_TAG v6.1.9
-  GIT_SHALLOW TRUE
-)
-FetchContent_MakeAvailable(ftxui)
-
-find_package(libzip REQUIRED)
-find_package(pugixml REQUIRED)
-
-# libbsdl — standalone BSDL parser (LGPL-2.1), dynamically linked from essim
-# (EUPL-1.2, which the LGPL permits). Path overridable via -DBSDL_DIR=...;
-# its CLI and tests are not needed inside essim's build.
+# ----------------------------------------------------------------- core deps
+# libbsdl — standalone BSDL parser (LGPL-2.1), dynamically linked (EUPL-1.2,
+# which the LGPL permits). Override its path with -DBSDL_DIR=...
 set(BSDL_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../libbsdl" CACHE PATH "libbsdl source tree")
 set(BSDL_BUILD_CLI   OFF CACHE BOOL "" FORCE)
 set(BSDL_BUILD_TESTS OFF CACHE BOOL "" FORCE)
 add_subdirectory(${BSDL_DIR} ${CMAKE_BINARY_DIR}/libbsdl)
 
-# Library target = everything except main.cpp; reused by `essim` and `essim_tests`.
-file(GLOB_RECURSE LIB_SOURCES "src/*.cpp")
-list(REMOVE_ITEM LIB_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/src/main.cpp")
+find_package(libzip REQUIRED)
+find_package(pugixml REQUIRED)
 
-add_library(essim_lib STATIC ${LIB_SOURCES})
-target_include_directories(essim_lib PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/src)
-target_link_libraries(essim_lib
+# =============================================================== essim_core
+# All business logic — domain model, importers, application operations
+# (src/core/{domain,imports,app}). Frontend-agnostic: it links NO GUI/TUI
+# toolkit, so every frontend and the test suite share the exact same core.
+file(GLOB_RECURSE CORE_SOURCES "src/core/*.cpp")
+add_library(essim_core STATIC ${CORE_SOURCES})
+target_include_directories(essim_core PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/src)
+target_link_libraries(essim_core
   PUBLIC
-    ftxui::screen
-    ftxui::dom
-    ftxui::component
     libzip::zip
     pugixml::pugixml
     bsdl::bsdl
 )
 
-add_executable(essim src/main.cpp)
-target_link_libraries(essim PRIVATE essim_lib)
+# =============================================================== frontend(s)
+# Pick the GUI/TUI frontend to build the `essim` binary against. Each frontend
+# is a self-contained src/frontends/<name>/ (own CMakeLists, GUI toolkit, and
+# main.cpp) that links essim_core. "none" builds the core + tests only — no GUI
+# toolkit is fetched. To add a frontend (e.g. a Qt GUI), create
+# src/frontends/gui/ and configure with -DESSIM_FRONTEND=gui.
+set(ESSIM_FRONTEND "tui" CACHE STRING
+    "Frontend to build: a directory name under src/frontends/, or 'none'")
+set_property(CACHE ESSIM_FRONTEND PROPERTY STRINGS tui none)
 
-# Tests
+if(ESSIM_FRONTEND STREQUAL "none")
+  message(STATUS "essim: ESSIM_FRONTEND=none — core + tests only (no frontend, no GUI toolkit)")
+elseif(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/src/frontends/${ESSIM_FRONTEND}/CMakeLists.txt")
+  message(STATUS "essim: building frontend '${ESSIM_FRONTEND}'")
+  add_subdirectory(src/frontends/${ESSIM_FRONTEND})
+else()
+  message(FATAL_ERROR
+    "Unknown ESSIM_FRONTEND '${ESSIM_FRONTEND}' — expected "
+    "src/frontends/${ESSIM_FRONTEND}/CMakeLists.txt, or 'none'.")
+endif()
+
+# =============================================================== tests (core)
+# The suite exercises essim_core only — no frontend, no GUI toolkit.
 include(CTest)
 if(BUILD_TESTING)
   set(CMAKE_POLICY_VERSION_MINIMUM 3.5)
@@ -65,20 +70,35 @@ if(BUILD_TESTING)
   FetchContent_MakeAvailable(doctest)
   unset(CMAKE_POLICY_VERSION_MINIMUM)
 
+  # Core tests — exercise essim_core only (tests/*.cpp, non-recursive, so the
+  # per-frontend tests under tests/<frontend>/ are not pulled in here).
   file(GLOB TEST_SOURCES "tests/*.cpp")
   if(TEST_SOURCES)
     add_executable(essim_tests ${TEST_SOURCES})
-    target_link_libraries(essim_tests PRIVATE essim_lib doctest::doctest)
+    target_link_libraries(essim_tests PRIVATE essim_core doctest::doctest)
     add_test(NAME essim_tests COMMAND essim_tests)
   endif()
+
+  # Per-frontend tests — tests/<frontend>/*.cpp, built and linked against that
+  # frontend's library only when the frontend itself is built.
+  if(TARGET essim_tui)
+    file(GLOB TUI_TEST_SOURCES "tests/tui/*.cpp")
+    if(TUI_TEST_SOURCES)
+      add_executable(essim_tui_tests
+        "${CMAKE_CURRENT_SOURCE_DIR}/tests/doctest_main.cpp" ${TUI_TEST_SOURCES})
+      target_link_libraries(essim_tui_tests PRIVATE essim_tui doctest::doctest)
+      add_test(NAME essim_tui_tests COMMAND essim_tui_tests)
+    endif()
+  endif()
 endif()
 
-# Documentation: Doxygen → XML → custom Python script → doc/api/ (Markdown rendered by gitea).
-# Optional — `doc` target is only created if Doxygen and Python 3 are present.
+# =============================================================== documentation
+# Doxygen → XML → gen_api_md.py → doc/api/, plus `essim --commands-md`. Needs the
+# `essim` binary, so it's only wired when a frontend that provides one is built.
 find_package(Doxygen COMPONENTS doxygen)
 find_package(Python3 COMPONENTS Interpreter)
 
-if(DOXYGEN_FOUND AND Python3_Interpreter_FOUND)
+if(TARGET essim AND DOXYGEN_FOUND AND Python3_Interpreter_FOUND)
   set(DOXYGEN_OUTPUT_DIR "${CMAKE_BINARY_DIR}/doc")
   file(MAKE_DIRECTORY "${DOXYGEN_OUTPUT_DIR}")
   configure_file(
@@ -103,11 +123,10 @@ if(DOXYGEN_FOUND AND Python3_Interpreter_FOUND)
     WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"
     COMMENT "Generating documentation (doxygen → gen_api_md.py → doc/api/, essim --commands-md → doc/user/commands.md)"
     VERBATIM)
-elseif(NOT DOXYGEN_FOUND AND NOT Python3_Interpreter_FOUND)
-  message(STATUS "doc: Doxygen and Python 3 not found — `doc` target disabled.")
+elseif(NOT TARGET essim)
+  message(STATUS "doc: no `essim` binary (ESSIM_FRONTEND=none) — `doc` target disabled.")
 elseif(NOT DOXYGEN_FOUND)
-  message(STATUS "doc: Doxygen not found — `doc` target disabled "
-                 "(install via `pacman -S doxygen`).")
+  message(STATUS "doc: Doxygen not found — `doc` target disabled.")
 else()
   message(STATUS "doc: Python 3 interpreter not found — `doc` target disabled.")
 endif()

src/core/app/export.cpp

@@ -0,0 +1,190 @@
+#include "core/app/export.hpp"
+
+#include "core/imports/ods_writer.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signal_type.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
+
+#include <cctype>
+#include <fstream>
+#include <string>
+
+namespace app {
+
+namespace {
+
+std::string to_lower(std::string s)
+{
+    for (char &c : s) c = (char)std::tolower((unsigned char)c);
+    return s;
+}
+
+// Minimal CSV quoter — wraps in "…" and doubles internal quotes when the field
+// contains a comma, quote, or newline.
+std::string csv_quote(const std::string &s)
+{
+    if (s.find_first_of(",\"\n") == std::string::npos)
+        return s;
+    std::string out = "\"";
+    for (char c : s) { if (c == '"') out += '"'; out += c; }
+    out += '"';
+    return out;
+}
+
+// Flatten one pin into the string slots an export row uses.
+void pin_side(Pin *p, std::string &mod, std::string &part, std::string &pin,
+              std::string &sig, std::string &type, std::string &suspect)
+{
+    if (!p) { mod = part = pin = sig = type = suspect = ""; return; }
+    mod  = (p->prnt && p->prnt->prnt) ? p->prnt->prnt->name : "";
+    part = p->prnt ? p->prnt->name : "";
+    pin  = p->name;
+    Signal *s = p->signal();
+    if (!s) {
+        sig = ""; type = "(NC)"; suspect = "";
+    } else {
+        sig = s->name;
+        type = signal_type_name(s->type);
+        suspect = (infer_signal_type(s->name) == SignalType::Power
+                   && s->type == SignalType::Other) ? "yes" : "no";
+    }
+}
+
+// Excel rejects /\?*:[] in sheet names; ODS forbids < > & in raw table names.
+// Sanitise to underscores and clip to Excel's 31-char hard limit.
+std::string sanitise_sheet_name(std::string name)
+{
+    for (char &ch : name)
+        if (ch == '/' || ch == '\\' || ch == '?' || ch == '*' || ch == ':'
+            || ch == '[' || ch == ']' || ch == '<' || ch == '>' || ch == '&')
+            ch = '_';
+    if (name.size() > 31) name = name.substr(0, 31);
+    return name;
+}
+
+ExportResult write_ods(const System *sys, const std::string &path)
+{
+    ExportResult r;
+    OdsWriter w;
+    for (auto &ckv : *sys->connections()) {
+        Connection *c = ckv.second;
+        OdsSheet *s = w.add_sheet(sanitise_sheet_name(c->name));
+
+        std::string lmod = c->m1 ? c->m1->name : "";
+        std::string lprt = c->p1 ? c->p1->name : "";
+        std::string rmod = c->m2 ? c->m2->name : "";
+        std::string rprt = c->p2 ? c->p2->name : "";
+
+        // Meta header: label/value rows, a blank row, then the column headers.
+        auto meta = [&](int row, const std::string &k, const std::string &v) {
+            s->set(row, 0, k);
+            s->set(row, 1, v);
+        };
+        meta(0, "Connection", c->name);
+        meta(1, "Transform",  c->transform_name);
+        meta(2, "Left",       lmod + " / " + lprt);
+        meta(3, "Right",      rmod + " / " + rprt);
+        // Row 4 left blank by design.
+
+        const int HDR = 5;
+        s->set_header_row(HDR);
+        const char *hdr[] = {
+            "left_pin", "left_signal", "left_type", "left_suspect",
+            "right_pin", "right_signal", "right_type", "right_suspect",
+            "type_mismatch"};
+        for (int i = 0; i < 9; ++i) s->set(HDR, i, hdr[i]);
+
+        int row = HDR + 1;
+        for (auto &wp : c->pin_map) {
+            std::string lm, lp, ln, ls, lt, lsus;
+            std::string rm, rp, rn, rs, rt, rsus;
+            pin_side(wp.first,  lm, lp, ln, ls, lt, lsus);
+            pin_side(wp.second, rm, rp, rn, rs, rt, rsus);
+            std::string tm = (lt != "(NC)" && rt != "(NC)" && lt != rt) ? "yes" : "no";
+            s->set(row, 0, ln); s->set(row, 1, ls);
+            s->set(row, 2, lt); s->set(row, 3, lsus);
+            s->set(row, 4, rn); s->set(row, 5, rs);
+            s->set(row, 6, rt); s->set(row, 7, rsus);
+            s->set(row, 8, tm);
+            ++row; ++r.rows;
+        }
+    }
+
+    std::string err;
+    if (!w.save(path, err)) {
+        r.error = err;
+        return r;
+    }
+    r.ok = true;
+    r.sheets = (int)sys->connections()->size();
+    return r;
+}
+
+ExportResult write_csv(const System *sys, const std::string &path)
+{
+    ExportResult r;
+    std::ofstream f(path);
+    if (!f) {
+        r.error = "cannot open '" + path + "' for writing";
+        return r;
+    }
+
+    // One rectangular table: each row repeats the per-connection constants so
+    // the file stays parser-friendly (pandas / awk / spreadsheet).
+    f << "connection,transform,"
+         "left_module,left_part,"
+         "left_pin,left_signal,left_type,left_suspect,"
+         "right_module,right_part,"
+         "right_pin,right_signal,right_type,right_suspect,"
+         "type_mismatch\n";
+
+    for (auto &ckv : *sys->connections()) {
+        Connection *c = ckv.second;
+        for (auto &wp : c->pin_map) {
+            std::string lm, lp, ln, ls, lt, lsus;
+            std::string rm, rp, rn, rs, rt, rsus;
+            pin_side(wp.first,  lm, lp, ln, ls, lt, lsus);
+            pin_side(wp.second, rm, rp, rn, rs, rt, rsus);
+            std::string tm = (lt != "(NC)" && rt != "(NC)" && lt != rt) ? "yes" : "no";
+            f << csv_quote(c->name)           << ','
+              << csv_quote(c->transform_name) << ','
+              << csv_quote(lm) << ',' << csv_quote(lp) << ','
+              << csv_quote(ln) << ',' << csv_quote(ls) << ','
+              << csv_quote(lt) << ',' << csv_quote(lsus) << ','
+              << csv_quote(rm) << ',' << csv_quote(rp) << ','
+              << csv_quote(rn) << ',' << csv_quote(rs) << ','
+              << csv_quote(rt) << ',' << csv_quote(rsus) << ','
+              << tm << '\n';
+            ++r.rows;
+        }
+    }
+    r.ok = f.good();
+    if (!r.ok) r.error = "write error on '" + path + "'";
+    return r;
+}
+
+}  // namespace
+
+bool export_format_from_path(const std::string &path, ExportFormat &out)
+{
+    size_t dot = path.rfind('.');
+    std::string ext = (dot == std::string::npos) ? "" : to_lower(path.substr(dot));
+    if (ext == ".csv") { out = ExportFormat::Csv; return true; }
+    if (ext == ".ods") { out = ExportFormat::Ods; return true; }
+    return false;
+}
+
+ExportResult export_connections(const System *sys, const std::string &path,
+                                ExportFormat format)
+{
+    ExportResult r;
+    if (!sys) { r.error = "no system"; return r; }
+    return (format == ExportFormat::Ods) ? write_ods(sys, path)
+                                         : write_csv(sys, path);
+}
+
+}  // namespace app

src/core/app/export.hpp

@@ -0,0 +1,34 @@
+#ifndef _APP_EXPORT_HPP_
+#define _APP_EXPORT_HPP_
+
+#include <string>
+
+class System;
+
+// Application layer: UI-independent operations that any frontend (TUI, GUI, …)
+// can call. No console, no dialogs, no FTXUI — just System in, result out.
+namespace app {
+
+enum class ExportFormat { Csv, Ods };
+
+// Outcome of an export. The only side effect is writing the target file; the
+// caller renders `error` / the stats however it likes.
+struct ExportResult {
+    bool ok = false;
+    std::string error;  ///< human-readable, set when !ok
+    int sheets = 0;     ///< ODS: number of sheets (one per connection); 0 for CSV
+    int rows = 0;       ///< wires written
+};
+
+// Map a filename extension (.csv / .ods, case-insensitive) to a format.
+// Returns false if the extension is neither.
+bool export_format_from_path(const std::string &path, ExportFormat &out);
+
+// Export the system's connections to `path` in `format`. Builds the file and
+// returns stats or an error. Pure core — safe to call from any frontend.
+ExportResult export_connections(const System *sys, const std::string &path,
+                                ExportFormat format);
+
+}  // namespace app
+
+#endif  // _APP_EXPORT_HPP_

src/core/domain/component_kind.cpp

@@ -1,4 +1,4 @@
-#include "system/component_kind.hpp"
+#include "core/domain/component_kind.hpp"
 
 #include <cctype>
 #include <string>

src/core/domain/nets.cpp

@@ -1,11 +1,11 @@
-#include "system/nets.hpp"
+#include "core/domain/nets.hpp"
 
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <queue>
 #include <unordered_map>

src/core/domain/pin_name.cpp

@@ -1,4 +1,4 @@
-#include "system/pin_name.hpp"
+#include "core/domain/pin_name.hpp"
 
 #include <cstdio>
 #include <stdexcept>

src/core/domain/system.cpp

@@ -3,9 +3,9 @@
 
 #include "connect.hpp"
 #include "modules.hpp"
-#include "imports/import_altium.hpp"
-#include "imports/import_mentor.hpp"
-#include "imports/import_ods.hpp"
+#include "core/imports/import_altium.hpp"
+#include "core/imports/import_mentor.hpp"
+#include "core/imports/import_ods.hpp"
 
 System::System() : mods(nullptr), conns(nullptr)
 {

src/core/domain/system.hpp

@@ -1,7 +1,7 @@
 #ifndef _SYSTEM_HPP_
 #define _SYSTEM_HPP_
 
-#include "imports/import_base.hpp"
+#include "core/imports/import_base.hpp"
 
 #pragma once
 class Modules; ///< Forward declaration of the Modules class.

src/core/imports/import_altium.cpp

@@ -1,8 +1,8 @@
 #include "import_altium.hpp"
 
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
 
 #include <cctype>
 #include <string>

src/core/imports/import_base.hpp

@@ -4,8 +4,8 @@
 #include <string>
 #include <fstream>
 
-#include "system/parts.hpp"
-#include "system/signals.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/signals.hpp"
 
 /**
  * @brief Base class for importing data from a file.

src/core/imports/import_mentor.cpp

@@ -1,6 +1,6 @@
 #include "import_mentor.hpp"
-#include "system/pins.hpp"
-#include "system/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/parts.hpp"
 
 #include <cctype>
 #include <vector>

src/core/imports/import_ods.cpp

@@ -1,8 +1,8 @@
 #include "import_ods.hpp"
 
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
 
 #include <pugixml.hpp>
 #include <zip.h>

src/frontends/tui/CMakeLists.txt

@@ -0,0 +1,35 @@
+# TUI frontend (FTXUI). Builds the `essim` executable against essim_core.
+#
+# A frontend is self-contained here: it pulls its own GUI toolkit, compiles its
+# sources into a library that links essim_core, and produces the `essim` binary
+# from its own entry point (main.cpp). To add another frontend, create a sibling
+# src/frontends/<name>/ with the same shape and select it with
+# -DESSIM_FRONTEND=<name>.
+
+set(FTXUI_BUILD_DOCS OFF CACHE INTERNAL "")
+set(FTXUI_BUILD_EXAMPLES OFF CACHE INTERNAL "")
+set(FTXUI_BUILD_TESTS OFF CACHE INTERNAL "")
+set(FTXUI_ENABLE_INSTALL OFF CACHE INTERNAL "")
+
+FetchContent_Declare(ftxui
+  GIT_REPOSITORY https://github.com/ArthurSonzogni/FTXUI.git
+  GIT_TAG v6.1.9
+  GIT_SHALLOW TRUE
+)
+FetchContent_MakeAvailable(ftxui)
+
+# Frontend library = every .cpp here except the entry point.
+file(GLOB TUI_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/*.cpp")
+list(REMOVE_ITEM TUI_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/main.cpp")
+
+add_library(essim_tui STATIC ${TUI_SOURCES})
+target_link_libraries(essim_tui
+  PUBLIC
+    essim_core
+    ftxui::screen
+    ftxui::dom
+    ftxui::component
+)
+
+add_executable(essim "${CMAKE_CURRENT_SOURCE_DIR}/main.cpp")
+target_link_libraries(essim PRIVATE essim_tui)

src/frontends/tui/commands.cpp

@@ -1,21 +1,21 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/analysis.hpp"
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/nets.hpp"
-#include "system/parts.hpp"
-#include "system/persist.hpp"
-#include "system/pin_role.hpp"
-#include "system/pin_model.hpp"
-#include "system/bsdl_model.hpp"
-#include "system/bsdl_check.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
-#include "system/transform.hpp"
-#include "system/transform_vpx.hpp"
+#include "core/domain/analysis.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/nets.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/persist.hpp"
+#include "core/domain/pin_role.hpp"
+#include "core/domain/pin_model.hpp"
+#include "core/domain/bsdl_model.hpp"
+#include "core/domain/bsdl_check.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
+#include "core/domain/transform.hpp"
+#include "core/domain/transform_vpx.hpp"
 
 #include <algorithm>
 #include <cctype>

src/frontends/tui/commands_export.cpp

@@ -0,0 +1,70 @@
+#include "frontends/tui/tui.hpp"
+
+#include "core/app/export.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/system.hpp"
+
+#include <string>
+#include <vector>
+
+// Thin UI wrapper around app::export_connections — this file only resolves
+// arguments / the file dialog and renders the result. All the actual export
+// (CSV / ODS building, file writing) lives in src/app/export.cpp.
+void Tui::RegisterExportCommands() {
+    commands["export"] = {
+        {{"kind [connections]", Completion::None},
+         {"filename (.csv)",    Completion::Path}},
+        [this](const std::vector<std::string> &args) {
+            if (!sys) { Print("no system: run 'new' first."); return; }
+
+            if (args.empty()) {
+                // Bare → the generic file dialog. The CSV/ODS filter rewrites
+                // the extension; the action below dispatches on it.
+                OpenFileDialog(
+                    "Export — connections",
+                    "export.connections",
+                    "connections.csv",
+                    {{"CSV", ".csv"}, {"ODS", ".ods"}},
+                    [this](const std::string &path) {
+                        Dispatch("export connections " + path);
+                    });
+                return;
+            }
+            if (args.size() != 2) {
+                Print("usage: export <kind> <file>   (or no args for the dialog)");
+                return;
+            }
+            const std::string &kind = args[0];
+            const std::string &path = args[1];
+
+            if (kind != "connections") {
+                ShowError("export: unknown kind '" + kind + "'\n"
+                          "Known kinds: connections");
+                return;
+            }
+
+            app::ExportFormat fmt;
+            if (!app::export_format_from_path(path, fmt)) {
+                ShowError("export: unknown extension — accepted: .csv, .ods");
+                return;
+            }
+
+            app::ExportResult r = app::export_connections(sys.get(), path, fmt);
+            if (!r.ok) {
+                ShowError("export failed:\n" + r.error);
+                return;
+            }
+
+            const bool ods = (fmt == app::ExportFormat::Ods);
+            std::string msg = ods ? "export connections (.ods): "
+                                  : "export connections (.csv): ";
+            if (ods) msg += std::to_string(r.sheets) + " sheet(s), ";
+            Print(msg + std::to_string(r.rows) + " wire(s) → " + path);
+        },
+        /*prompt_for_missing=*/ false,
+        "export structured data to CSV / ODS (kinds: connections; "
+        "bare form opens the file-picker dialog)",
+        /*scriptable=*/ true,
+        /*interactive=*/ true,
+    };
+}

src/frontends/tui/completion.cpp

@@ -1,5 +1,5 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
 #include <cctype>
 #include <cstdlib>

src/frontends/tui/main.cpp

@@ -1,4 +1,4 @@
-#include "tui/tui.hpp"
+#include "frontends/tui/tui.hpp"
 
 #include <fstream>
 #include <iostream>

src/frontends/tui/screen_analyze.cpp

@@ -1,15 +1,15 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/analysis.hpp"
-#include "system/bsdl_check.hpp"
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/nets.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/analysis.hpp"
+#include "core/domain/bsdl_check.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/nets.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_confirm.cpp

@@ -1,4 +1,4 @@
-#include "tui/tui.hpp"
+#include "frontends/tui/tui.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/event.hpp>

src/frontends/tui/screen_connect.cpp

@@ -1,11 +1,11 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/system.hpp"
-#include "system/transform.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/system.hpp"
+#include "core/domain/transform.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_dashboard.cpp

@@ -1,15 +1,15 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/analysis.hpp"
-#include "system/bsdl_check.hpp"
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/nets.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/analysis.hpp"
+#include "core/domain/bsdl_check.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/nets.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/dom/elements.hpp>
@@ -44,6 +44,8 @@ Component Tui::BuildDashboardScreen() {
 
       Element early_help = RenderHelpPanel("dashboard", {
           {"c",      "console"},
+          {"o",      "open/run a script"},
+          {"r",      "restore a snapshot"},
           {"a",      "analyze"},
           {"h",      "help screen"},
           {"q",      "quit"},
@@ -56,8 +58,8 @@ Component Tui::BuildDashboardScreen() {
               separator(),
               hbox({
                   vbox({
-                      text("  no system loaded — run 'new' or 'restore <file>'") | dim,
-                      text("  (press 'c' for the console, or Ctrl-P for the palette)") | dim,
+                      text("  no system loaded") | dim,
+                      text("  (press 'o' open a script · 'r' restore a snapshot · 'c' console · Ctrl-P palette)") | dim,
                       filler(),
                   }) | flex,
                   separator(),
@@ -311,6 +313,7 @@ Component Tui::BuildDashboardScreen() {
           {"x",      "export"},
           {"o",      "open/run a script"},
           {"s",      "save system"},
+          {"r",      "restore a snapshot"},
           {"PgUp",   "scroll up"},
           {"PgDn",   "scroll down"},
           {"Home",   "scroll top"},

src/frontends/tui/screen_error.cpp

@@ -1,4 +1,4 @@
-#include "tui/tui.hpp"
+#include "frontends/tui/tui.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/event.hpp>

src/frontends/tui/screen_explore.cpp

@@ -1,13 +1,13 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/nets.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/nets.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_filedialog.cpp

@@ -1,5 +1,5 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>
@@ -54,11 +54,13 @@ void Tui::OpenFileDialog(std::string title,
                          std::string persist_key,
                          std::string default_filename,
                          std::vector<FilenameFilter> filters,
-                         std::function<void(const std::string &)> on_confirm) {
+                         std::function<void(const std::string &)> on_confirm,
+                         bool confirm_overwrite) {
     file_dialog.title       = std::move(title);
     file_dialog.persist_key = std::move(persist_key);
     file_dialog.on_confirm  = std::move(on_confirm);
     file_dialog.filters     = std::move(filters);
+    file_dialog.confirm_overwrite = confirm_overwrite;
     file_dialog.filter_labels.clear();
     for (const auto &f : file_dialog.filters)
         file_dialog.filter_labels.push_back(f.label);
@@ -122,7 +124,7 @@ void Tui::ConfirmFileDialog() {
     // Overwrite guard: if the file already exists, ask before letting
     // the action proceed. Esc / No cancels; Yes runs the action.
     std::error_code ec;
-    if (fs::exists(full, ec) && !ec) {
+    if (file_dialog.confirm_overwrite && fs::exists(full, ec) && !ec) {
         ShowConfirm("File '" + full.string() + "' already exists.\n"
                     "Overwrite?",
                     invoke);

src/frontends/tui/screen_help.cpp

@@ -1,5 +1,5 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_main.cpp

@@ -1,5 +1,5 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>
@@ -89,18 +89,8 @@ Component Tui::BuildMainScreen(ScreenInteractive &screen) {
             }) | flex,
         }) | border;
 
-        if (loading) {
-            int total = (int)loading_lines.size();
-            std::string progress = std::to_string(loading_executed) + " / "
-                                 + std::to_string(total) + " lines";
-            auto modal = vbox({
-                text(" Computing… ") | bold | center,
-                separator(),
-                text(loading_filename) | center,
-                text(progress) | center,
-            }) | borderDouble | size(WIDTH, GREATER_THAN, 40);
-            return dbox({base, modal | center});
-        }
+        // The "Computing…" overlay is rendered globally in Run(), so it shows
+        // on whatever screen is active while a script loads.
         return base;
     });
 }

src/frontends/tui/screen_palette.cpp

@@ -1,9 +1,9 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/modules.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_settype.cpp

@@ -1,13 +1,13 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/pin_model.hpp"
-#include "system/pin_role.hpp"
-#include "system/pins.hpp"
-#include "system/system.hpp"
-#include "system/transform_vpx.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pin_model.hpp"
+#include "core/domain/pin_role.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/system.hpp"
+#include "core/domain/transform_vpx.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/screen_sigtype_modal.cpp

@@ -1,8 +1,8 @@
-#include "tui/tui.hpp"
+#include "frontends/tui/tui.hpp"
 
-#include "system/modules.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>

src/frontends/tui/shell.cpp

@@ -1,9 +1,9 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
-#include "system/modules.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <cctype>
 #include <chrono>
@@ -296,8 +296,10 @@ void Tui::Source(const std::string &filename) {
     loading_executed = 0;
     loading_lineno = 0;
     loading_prev_in_source = in_source;
+    source_origin_screen = screen_idx;  // a sourced line that leaves this screen aborts
     in_source = true;
     loading = true;
+    computing_open = true;  // raise the global "Computing…" progress modal
 
     if (!screen_ptr) {
         // Headless fallback (e.g. tests): drain synchronously.
@@ -346,11 +348,12 @@ void Tui::ProcessNextSourceLine() {
         Submit();
         ++loading_executed;
 
-        if (screen_idx != 0) {
+        if (screen_idx != source_origin_screen) {
             Print("source: line " + std::to_string(loading_lineno)
                   + " is interactive (would open a screen) — aborting.");
-            screen_idx = 0;
+            screen_idx = source_origin_screen;
             loading.store(false);
+            computing_open = false;
             tick_in_flight.store(false);
             in_source = loading_prev_in_source;
             return;
@@ -363,6 +366,7 @@ void Tui::ProcessNextSourceLine() {
     Print("source: " + loading_filename
           + "  (" + std::to_string(loading_executed) + " line(s))");
     loading.store(false);
+    computing_open = false;
     tick_in_flight.store(false);
     in_source = loading_prev_in_source;
 }

src/frontends/tui/tui.cpp

@@ -1,10 +1,11 @@
-#include "tui/tui.hpp"
+#include "frontends/tui/tui.hpp"
 
-#include "system/system.hpp"
+#include "core/domain/system.hpp"
 
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/event.hpp>
 #include <ftxui/component/screen_interactive.hpp>
+#include <ftxui/dom/elements.hpp>
 
 using namespace ftxui;
 
@@ -58,10 +59,31 @@ void Tui::Run() {
     auto with_error   = with_confirm
                       | Modal(BuildErrorModal(), &error_open);
 
-    auto root = CatchEvent(with_error, [this](Event e) {
+    // Global "Computing…" progress modal while a script loads — a proper Modal
+    // (like the palette / file dialog), so it shows on any screen, e.g. when a
+    // script is opened from the dashboard. The Renderer re-reads the live
+    // progress every frame.
+    auto computing_modal = Renderer([this] {
+        std::string progress = std::to_string(loading_executed) + " / "
+                             + std::to_string((int)loading_lines.size()) + " lines";
+        return vbox({
+                   text(" Computing… ") | bold | center,
+                   separator(),
+                   text(loading_filename) | center,
+                   text(progress) | center,
+               }) | borderDouble | size(WIDTH, GREATER_THAN, 40);
+    });
+    auto with_loading = with_error | Modal(computing_modal, &computing_open);
+
+    auto root = CatchEvent(with_loading, [this](Event e) {
+        // Source ticks drive the line-by-line loader; handle them on ANY screen
+        // (and before the modal guard) so `source` keeps running while the
+        // Computing modal is up.
+        if (e == Event::Special("\x02tick")) { ProcessNextSourceLine(); return true; }
+
         // Modals own their events while open. Error modal sits on top.
         if (error_open || confirm_open || palette_open
-            || sigtype_dialog_open || file_dialog.open) return false;
+            || sigtype_dialog_open || file_dialog.open || computing_open) return false;
 
         // Ctrl-P opens the palette from any screen.
         if (e == Event::CtrlP) { OpenPalette(); return true; }
@@ -106,7 +128,8 @@ void Tui::Run() {
                                "dashboard.source", "", {},
                                [this](const std::string &path) {
                                    Dispatch("source " + path);
-                               });
+                               },
+                               /*confirm_overwrite=*/false);  // opening, not saving
                 return true;
             }
             if (e == Event::Character("s")) {   // save the system snapshot
@@ -118,6 +141,15 @@ void Tui::Run() {
                                    });
                 return true;
             }
+            if (e == Event::Character("r")) {   // restore a saved system
+                OpenFileDialog("Restore system — load a snapshot",
+                               "dashboard.restore", "", {},
+                               [this](const std::string &path) {
+                                   Dispatch("restore " + path);
+                               },
+                               /*confirm_overwrite=*/false);  // opening, not saving
+                return true;
+            }
             return false;
 
         case 3:  // explore
@@ -152,7 +184,6 @@ void Tui::Run() {
             return false;
 
         default:  // 0: main (console / log view)
-            if (e == Event::Special("\x02tick")) { ProcessNextSourceLine(); return true; }
             if (e == Event::Escape) {
                 if (!pending.empty()) { CancelPending(); return true; }
                 screen_idx = 4; return true;

src/frontends/tui/tui.hpp

@@ -103,6 +103,8 @@ class Tui {
     int loading_executed;
     int loading_lineno;
     bool loading_prev_in_source;
+    int source_origin_screen = 0;  ///< screen a `source` started from; a sourced line that navigates away (opens an interactive screen) aborts it.
+    bool computing_open = false;   ///< drives the global "Computing…" progress modal while a script loads.
     ftxui::ScreenInteractive *screen_ptr;  ///< set in Run() so Source() can post events.
 
     // ---- Dashboard scroll state (0 = top; grows as the user scrolls down) ----
@@ -149,6 +151,7 @@ private:
         std::vector<std::string> filter_labels;  ///< parallel to `filters`
         int filter_idx = 0;
         std::function<void(const std::string &)> on_confirm;
+        bool confirm_overwrite = true;  ///< false in "open" mode — skip the overwrite prompt.
     };
     FileDialogState file_dialog;
 
@@ -272,11 +275,14 @@ private:
     // dir + filename are stored (one tiny file per key under the user
     // data directory). `on_confirm` runs when the user presses Enter on
     // the action button — it receives the absolute path the user picked.
+    // `confirm_overwrite = false` puts the dialog in "open" mode: it skips the
+    // "file exists — overwrite?" prompt (you *want* an existing file to open).
     void OpenFileDialog(std::string title,
                         std::string persist_key,
                         std::string default_filename,
                         std::vector<FilenameFilter> filters,
-                        std::function<void(const std::string &)> on_confirm);
+                        std::function<void(const std::string &)> on_confirm,
+                        bool confirm_overwrite = true);
     void ConfirmFileDialog();
     ftxui::Component BuildSignalTypeModal();
     ftxui::Component BuildPaletteModal();

src/frontends/tui/tui_helpers.cpp

@@ -1,4 +1,4 @@
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
 #include <ftxui/dom/elements.hpp>
 

src/tui/commands_export.cpp

@@ -1,235 +0,0 @@
-#include "tui/tui.hpp"
-#include "tui/tui_helpers.hpp"
-
-#include "imports/ods_writer.hpp"
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signal_type.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
-
-#include <fstream>
-#include <string>
-#include <vector>
-
-namespace {
-
-// Minimal CSV quoter — wraps in `"…"` and doubles internal quotes when
-// the field contains a comma, quote, or newline. Local to this file.
-std::string csv_quote(const std::string &s) {
-    bool needs = s.find_first_of(",\"\n") != std::string::npos;
-    if (!needs) return s;
-    std::string out = "\"";
-    for (char c : s) { if (c == '"') out += '"'; out += c; }
-    out += '"';
-    return out;
-}
-
-// Flatten one pin into the 6 string slots the export row uses.
-void pin_side(Pin *p, std::string &mod, std::string &part,
-              std::string &pin, std::string &sig,
-              std::string &type, std::string &suspect) {
-    if (!p) { mod = part = pin = sig = type = suspect = ""; return; }
-    mod  = (p->prnt && p->prnt->prnt) ? p->prnt->prnt->name : "";
-    part = p->prnt ? p->prnt->name : "";
-    pin  = p->name;
-    Signal *s = p->signal();
-    if (!s) {
-        sig = ""; type = "(NC)"; suspect = "";
-    } else {
-        sig = s->name;
-        type = signal_type_name(s->type);
-        suspect = (infer_signal_type(s->name) == SignalType::Power
-                   && s->type == SignalType::Other) ? "yes" : "no";
-    }
-}
-
-}  // namespace
-
-void Tui::RegisterExportCommands() {
-    commands["export"] = {
-        {{"kind [connections]", Completion::None},
-         {"filename (.csv)",    Completion::Path}},
-        [this](const std::vector<std::string> &args) {
-            if (!sys) { Print("no system: run 'new' first."); return; }
-            if (args.empty()) {
-                // Bare → reuse the generic file dialog. Filters give a
-                // one-keystroke CSV/ODS toggle; picking either rewrites
-                // the filename's extension, and the action below
-                // dispatches on that extension.
-                OpenFileDialog(
-                    "Export — connections",
-                    "export.connections",
-                    "connections.csv",
-                    {{"CSV", ".csv"}, {"ODS", ".ods"}},
-                    [this](const std::string &path) {
-                        Dispatch("export connections " + path);
-                    });
-                return;
-            }
-            if (args.size() != 2) {
-                Print("usage: export <kind> <file>   (or no args for the dialog)");
-                return;
-            }
-            const std::string &kind = args[0];
-            const std::string &path = args[1];
-
-            if (kind == "connections") {
-                // Accepted extensions: `.csv` (flat file) and `.ods`
-                // (one sheet per connection). Anything else is an error.
-                std::string ext;
-                {
-                    size_t dot = path.rfind('.');
-                    if (dot != std::string::npos) ext = ToLower(path.substr(dot));
-                }
-                bool ods = (ext == ".ods");
-                bool csv = (ext == ".csv");
-                if (!ods && !csv) {
-                    ShowError("export: unknown extension '"
-                              + (ext.empty() ? std::string("(none)") : ext)
-                              + "'\nAccepted: .csv, .ods");
-                    return;
-                }
-
-                if (ods) {
-                    OdsWriter w;
-                    int total = 0;
-                    for (auto &ckv : *sys->connections()) {
-                        Connection *c = ckv.second;
-                        // Sheet names: Excel rejects /\?*:[] characters,
-                        // ODS forbids < > & in raw cell/table names.
-                        // Sanitise to underscores; clip to 31 chars
-                        // (Excel's hard limit).
-                        std::string sname = c->name;
-                        for (char &ch : sname)
-                            if (ch == '/' || ch == '\\' || ch == '?' || ch == '*'
-                                || ch == ':' || ch == '[' || ch == ']'
-                                || ch == '<' || ch == '>' || ch == '&') ch = '_';
-                        if (sname.size() > 31) sname = sname.substr(0, 31);
-                        OdsSheet *s = w.add_sheet(sname);
-
-                        // Pull the constants for this connection once.
-                        // `transform`, the left module/part, and the
-                        // right module/part don't vary across the wires
-                        // of a single connection — putting them in
-                        // every row was repetitive.
-                        std::string lmod, lprt;
-                        std::string rmod, rprt;
-                        if (c->m1) lmod = c->m1->name;
-                        if (c->p1) lprt = c->p1->name;
-                        if (c->m2) rmod = c->m2->name;
-                        if (c->p2) rprt = c->p2->name;
-
-                        // Meta header above the table: 5 rows of label /
-                        // value, then a blank, then the column headers
-                        // on row 6 (index 5).
-                        auto meta = [&](int r, const std::string &k,
-                                         const std::string &v) {
-                            s->set(r, 0, k);
-                            s->set(r, 1, v);
-                        };
-                        meta(0, "Connection", c->name);
-                        meta(1, "Transform",  c->transform_name);
-                        meta(2, "Left",       lmod + " / " + lprt);
-                        meta(3, "Right",      rmod + " / " + rprt);
-                        // Row 4 left blank by design.
-
-                        const int HDR = 5;
-                        s->set_header_row(HDR);
-                        const char *hdr[] = {
-                            "left_pin", "left_signal", "left_type", "left_suspect",
-                            "right_pin", "right_signal", "right_type", "right_suspect",
-                            "type_mismatch"};
-                        for (int i = 0; i < 9; ++i) s->set(HDR, i, hdr[i]);
-
-                        int row = HDR + 1;
-                        for (auto &wp : c->pin_map) {
-                            std::string lm, lp, ln, ls, lt, lsus;
-                            std::string rm, rp, rn, rs, rt, rsus;
-                            pin_side(wp.first,  lm, lp, ln, ls, lt, lsus);
-                            pin_side(wp.second, rm, rp, rn, rs, rt, rsus);
-                            // `type_mismatch = yes` when both sides have a
-                            // real signal AND their types disagree (e.g.
-                            // Power ↔ Gnd, or Power ↔ Other).
-                            std::string tm = (lt != "(NC)" && rt != "(NC)" && lt != rt)
-                                            ? "yes" : "no";
-                            s->set(row, 0, ln); s->set(row, 1, ls);
-                            s->set(row, 2, lt); s->set(row, 3, lsus);
-                            s->set(row, 4, rn); s->set(row, 5, rs);
-                            s->set(row, 6, rt); s->set(row, 7, rsus);
-                            s->set(row, 8, tm);
-                            ++row; ++total;
-                        }
-                    }
-                    std::string err;
-                    if (!w.save(path, err)) {
-                        ShowError("export (.ods) failed:\n" + err);
-                        return;
-                    }
-                    Print("export connections (.ods): "
-                          + std::to_string(sys->connections()->size())
-                          + " sheet(s), " + std::to_string(total)
-                          + " wire(s) → " + path);
-                    return;
-                }
-
-                // Classic flat CSV: a single rectangular table — one
-                // header line, N data rows, every row carries the per-
-                // connection constants too. The 9 right-most column
-                // names match the ODS sheet headers exactly; the 5
-                // leading ones (connection, transform, left_module,
-                // left_part, right_module, right_part) correspond to
-                // the ODS meta block (Connection, Transform, Left,
-                // Right). Repeating the constants per row keeps the
-                // file parser-friendly (pandas / awk / spreadsheet).
-                std::ofstream f(path);
-                if (!f) {
-                    ShowError("export: cannot open '" + path + "' for writing");
-                    return;
-                }
-                f << "connection,transform,"
-                     "left_module,left_part,"
-                     "left_pin,left_signal,left_type,left_suspect,"
-                     "right_module,right_part,"
-                     "right_pin,right_signal,right_type,right_suspect,"
-                     "type_mismatch\n";
-
-                int rows = 0;
-                for (auto &ckv : *sys->connections()) {
-                    Connection *c = ckv.second;
-                    for (auto &wp : c->pin_map) {
-                        std::string lm, lp, ln, ls, lt, lsus;
-                        std::string rm, rp, rn, rs, rt, rsus;
-                        pin_side(wp.first,  lm, lp, ln, ls, lt, lsus);
-                        pin_side(wp.second, rm, rp, rn, rs, rt, rsus);
-                        std::string tm = "no";
-                        if (lt != "(NC)" && rt != "(NC)" && lt != rt) tm = "yes";
-                        f << csv_quote(c->name)           << ','
-                          << csv_quote(c->transform_name) << ','
-                          << csv_quote(lm) << ',' << csv_quote(lp) << ','
-                          << csv_quote(ln) << ',' << csv_quote(ls) << ','
-                          << csv_quote(lt) << ',' << csv_quote(lsus) << ','
-                          << csv_quote(rm) << ',' << csv_quote(rp) << ','
-                          << csv_quote(rn) << ',' << csv_quote(rs) << ','
-                          << csv_quote(rt) << ',' << csv_quote(rsus) << ','
-                          << tm << '\n';
-                        ++rows;
-                    }
-                }
-                Print("export connections (.csv): " + std::to_string(rows)
-                      + " wire(s) → " + path);
-                return;
-            }
-
-            ShowError("export: unknown kind '" + kind + "'\n"
-                      "Known kinds: connections");
-        },
-        /*prompt_for_missing=*/ false,
-        "export structured data to CSV / ODS (kinds: connections; "
-        "bare form opens the file-picker dialog)",
-        /*scriptable=*/ true,
-        /*interactive=*/ true,
-    };
-}

tests/test_analysis.cpp

@@ -1,11 +1,11 @@
 #include <doctest/doctest.h>
 
-#include "system/analysis.hpp"
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/analysis.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <memory>
 #include <string>

tests/test_bsdl_apply.cpp

@@ -1,14 +1,14 @@
 #include <doctest/doctest.h>
 
-#include "system/analysis.hpp"
-#include "system/bsdl_check.hpp"
-#include "system/bsdl_model.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/pin_spec.hpp"
-#include "system/system.hpp"
-#include "system/modules.hpp"
-#include "system/persist.hpp"
+#include "core/domain/analysis.hpp"
+#include "core/domain/bsdl_check.hpp"
+#include "core/domain/bsdl_model.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/pin_spec.hpp"
+#include "core/domain/system.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/persist.hpp"
 
 #include <cstdio>
 #include <fstream>

tests/test_bsdl_check.cpp

@@ -1,13 +1,13 @@
 #include <doctest/doctest.h>
 
-#include "system/analysis.hpp"
-#include "system/bsdl_check.hpp"
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/pin_spec.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/analysis.hpp"
+#include "core/domain/bsdl_check.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pin_spec.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <algorithm>
 #include <vector>

tests/test_component_kind.cpp

@@ -1,7 +1,7 @@
 #include <doctest/doctest.h>
 
-#include "system/component_kind.hpp"
-#include "system/parts.hpp"
+#include "core/domain/component_kind.hpp"
+#include "core/domain/parts.hpp"
 
 #include <memory>
 

tests/test_export.cpp

@@ -0,0 +1,76 @@
+#include <doctest/doctest.h>
+
+#include "core/app/export.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
+
+#include <cstdio>
+#include <fstream>
+#include <sstream>
+#include <string>
+
+namespace {
+
+std::string slurp(const std::string &path)
+{
+    std::ifstream f(path);
+    std::stringstream ss;
+    ss << f.rdbuf();
+    return ss.str();
+}
+
+}  // namespace
+
+TEST_CASE("export_format_from_path maps extensions") {
+    app::ExportFormat f;
+    CHECK(app::export_format_from_path("a.csv", f));
+    CHECK(f == app::ExportFormat::Csv);
+    CHECK(app::export_format_from_path("a.ODS", f));
+    CHECK(f == app::ExportFormat::Ods);
+    CHECK_FALSE(app::export_format_from_path("a.txt", f));
+    CHECK_FALSE(app::export_format_from_path("noext", f));
+}
+
+TEST_CASE("export_connections writes a flat CSV (no UI needed)") {
+    // Two cards, one wired pin pair via a connection.
+    System sys;
+    Module *a = sys.modules()->merge("A");
+    Module *b = sys.modules()->merge("B");
+    Part *ja = new Part("J1"); a->add(ja);
+    Part *jb = new Part("P1"); b->add(jb);
+    Pin *pa = new Pin("1"); ja->add(pa);
+    Pin *pb = new Pin("1"); jb->add(pb);
+    Signal *sa = a->signals->merge("NETA"); sa->add(pa); pa->connect(sa);
+    Signal *sb = b->signals->merge("NETB"); sb->add(pb); pb->connect(sb);
+
+    Connection *c = new Connection("A.J1<->B.P1", a, ja, b, jb);
+    c->transform_name = "identity";
+    c->pin_map.emplace_back(pa, pb);
+    sys.connections()->add(c);
+
+    const char *path = "test_export_out.csv";
+    app::ExportResult r = app::export_connections(&sys, path, app::ExportFormat::Csv);
+    CHECK(r.ok);
+    CHECK(r.rows == 1);
+
+    std::string out = slurp(path);
+    CHECK(out.find("connection,transform,") == 0);           // header present
+    CHECK(out.find("A.J1<->B.P1") != std::string::npos);     // connection name
+    CHECK(out.find("identity") != std::string::npos);        // transform
+    CHECK(out.find("NETA") != std::string::npos);            // left signal
+    CHECK(out.find("NETB") != std::string::npos);            // right signal
+
+    std::remove(path);
+}
+
+TEST_CASE("export_connections reports a bad path instead of crashing") {
+    System sys;
+    app::ExportResult r = app::export_connections(
+        &sys, "/nonexistent-dir-xyz/out.csv", app::ExportFormat::Csv);
+    CHECK_FALSE(r.ok);
+    CHECK_FALSE(r.error.empty());
+}

tests/test_nc_origin.cpp

@@ -1,11 +1,11 @@
 #include <doctest/doctest.h>
 
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/persist.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/persist.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <filesystem>
 #include <memory>

tests/test_persist.cpp

@@ -1,12 +1,12 @@
 #include <doctest/doctest.h>
 
-#include "system/connect.hpp"
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/persist.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
+#include "core/domain/connect.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/persist.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
 
 #include <filesystem>
 #include <memory>

tests/test_pin_model.cpp

@@ -1,9 +1,9 @@
 #include <doctest/doctest.h>
 
-#include "system/parts.hpp"
-#include "system/pin_model.hpp"
-#include "system/pin_spec.hpp"
-#include "system/pins.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pin_model.hpp"
+#include "core/domain/pin_spec.hpp"
+#include "core/domain/pins.hpp"
 
 #include <string>
 #include <vector>

tests/test_pin_name.cpp

@@ -1,9 +1,9 @@
 #include <doctest/doctest.h>
 
-#include "system/parts.hpp"
-#include "system/pin_name.hpp"
-#include "system/pins.hpp"
-#include "system/transform.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pin_name.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/transform.hpp"
 
 #include <memory>
 

tests/test_signal_type.cpp

@@ -1,6 +1,6 @@
 #include <doctest/doctest.h>
 
-#include "system/signal_type.hpp"
+#include "core/domain/signal_type.hpp"
 
 TEST_CASE("signal_type_name round-trips with from_name") {
     SignalType t;

tests/test_vpx_transform.cpp

@@ -1,12 +1,12 @@
 #include <doctest/doctest.h>
 
-#include "system/modules.hpp"
-#include "system/parts.hpp"
-#include "system/pins.hpp"
-#include "system/signals.hpp"
-#include "system/system.hpp"
-#include "system/transform.hpp"
-#include "system/transform_vpx.hpp"
+#include "core/domain/modules.hpp"
+#include "core/domain/parts.hpp"
+#include "core/domain/pins.hpp"
+#include "core/domain/signals.hpp"
+#include "core/domain/system.hpp"
+#include "core/domain/transform.hpp"
+#include "core/domain/transform_vpx.hpp"
 
 #include <map>
 #include <memory>

tests/tui/test_helpers.cpp

@@ -1,6 +1,6 @@
 #include <doctest/doctest.h>
 
-#include "tui/tui_helpers.hpp"
+#include "frontends/tui/tui_helpers.hpp"
 
 #include <algorithm>
 #include <vector>