diff --git a/DESIGN.md b/DESIGN.md
index 8479b43..e45b849 100644
--- a/DESIGN.md
+++ b/DESIGN.md
@@ -49,7 +49,8 @@ src/
     tui_helpers.{hpp,cpp}  Free helpers: ToLower, NaturalLess, LongestCommonPrefix
     shell.cpp              Print, Submit, Dispatch, Finalize, Tokenize, history persistence
     completion.cpp         CompleteCommand, CompletePath, CompleteInline
-    commands.cpp           RegisterCommands (all built-in commands declared here)
+    commands.cpp           RegisterCommands (orchestrator + lifecycle / shell / topology commands)
+    commands_export.cpp    RegisterExportCommands (export → CSV / ODS, file-dialog hook)
     screen_main.cpp        BuildMainScreen (visualisation area + bottom input)
     screen_connect.cpp     BuildConnectScreen + shared RefreshFilteredPartList helper
     screen_settype.cpp     BuildSettypeScreen
@@ -162,6 +163,8 @@ Exposed as the `analyze` shell command which prints groups (sorted by module + l
 
 Everything is recomputed every frame so manual overrides via the signal-type popup are reflected immediately. Esc returns to the dashboard. The dashboard's previous `[v]erify` letter shortcut was removed — its content is fully covered by this screen. The textual `verify` / `analyze` commands still exist for scripts.
 
+**Command group factorisation**: `RegisterCommands()` in `commands.cpp` owns most built-ins, but self-contained groups live in their own files (one `Register<X>Commands()` member each). Today only `RegisterExportCommands()` in `commands_export.cpp` follows the pattern. Adding a new group is mechanical: declare a new member in `tui.hpp`'s `private:` section, define it in `commands_<group>.cpp`, and call it from the orchestrator. Each group can have file-local helpers (e.g. `commands_export.cpp` has its own anonymous-namespace `csv_quote` and `pin_side`).
+
 **Generic file-picker dialog** (`screen_filedialog.cpp`): one reusable modal for every "pick a path" interaction. State lives in `Tui::file_dialog` (a single `FileDialogState`); attached to the tab tree via `Modal(BuildFileDialog(), &file_dialog.open)` in `Run()`. API:
 
 - `OpenFileDialog(title, persist_key, default_filename, filters, on_confirm)` — opens the modal, restoring the last-used `(dir, filename)` for `persist_key` if previously saved.
diff --git a/src/tui/commands.cpp b/src/tui/commands.cpp
index be0c095..f112823 100644
--- a/src/tui/commands.cpp
+++ b/src/tui/commands.cpp
@@ -1,7 +1,6 @@
 #include "tui/tui.hpp"
 #include "tui/tui_helpers.hpp"
 
-#include "imports/ods_writer.hpp"
 #include "system/analysis.hpp"
 #include "system/connect.hpp"
 #include "system/modules.hpp"
@@ -206,180 +205,6 @@ void Tui::RegisterCommands() {
         "write the current system snapshot to a file",
     };
 
-    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. The kind defaults
-                // to "connections" (the only one today); when more kinds
-                // are added, prompt for it inside the dialog before the
-                // filename step. Filters give the user a one-keystroke
-                // toggle between CSV and ODS — 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];
-
-            // Minimal CSV quoter — wraps in `"…"` and doubles internal
-            // quotes when the field contains a comma, quote, or newline.
-            auto q = [](const std::string &s) -> std::string {
-                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;
-            };
-
-            if (kind == "connections") {
-                auto 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";
-                    }
-                };
-
-                // Dispatch on extension. Accepted: `.csv` (flat file) and
-                // `.ods` (one sheet per connection). Anything else is an
-                // error — silently writing a CSV under a `.xyz` filename
-                // would be confusing.
-                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 can't contain '/' in some viewers
-                        // (LibreOffice tolerates it, Excel rejects it).
-                        // Sanitise just in case.
-                        std::string sname = c->name;
-                        for (char &ch : sname)
-                            if (ch == '/' || ch == '\\' || ch == '?' || ch == '*'
-                                || ch == ':' || ch == '[' || ch == ']') ch = '_';
-                        OdsSheet *s = w.add_sheet(sname);
-                        const char *hdr[] = {
-                            "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",
-                            "mixed"};
-                        for (int i = 0; i < 14; ++i) s->set(0, i, hdr[i]);
-                        int row = 1;
-                        for (auto &wp : c->pin_map) {
-                            std::string lm, lp, ln, ls, lt, lsus;
-                            std::string rm, rp, rn, rs, rt, rsus;
-                            side(wp.first,  lm, lp, ln, ls, lt, lsus);
-                            side(wp.second, rm, rp, rn, rs, rt, rsus);
-                            std::string mixed = (lt != "(NC)" && rt != "(NC)" && lt != rt)
-                                              ? "yes" : "no";
-                            s->set(row, 0,  c->transform_name);
-                            s->set(row, 1,  lm); s->set(row, 2,  lp);
-                            s->set(row, 3,  ln); s->set(row, 4,  ls);
-                            s->set(row, 5,  lt); s->set(row, 6,  lsus);
-                            s->set(row, 7,  rm); s->set(row, 8,  rp);
-                            s->set(row, 9,  rn); s->set(row, 10, rs);
-                            s->set(row, 11, rt); s->set(row, 12, rsus);
-                            s->set(row, 13, mixed);
-                            ++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;
-                }
-
-                // CSV fallback.
-                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,"
-                     "mixed\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;
-                        side(wp.first,  lm, lp, ln, ls, lt, lsus);
-                        side(wp.second, rm, rp, rn, rs, rt, rsus);
-                        std::string mixed = "no";
-                        if (lt != "(NC)" && rt != "(NC)" && lt != rt) mixed = "yes";
-                        f << q(c->name) << ',' << q(c->transform_name) << ','
-                          << q(lm) << ',' << q(lp) << ',' << q(ln) << ','
-                          << q(ls) << ',' << q(lt) << ',' << q(lsus) << ','
-                          << q(rm) << ',' << q(rp) << ',' << q(rn) << ','
-                          << q(rs) << ',' << q(rt) << ',' << q(rsus) << ','
-                          << mixed << '\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 (kinds: connections; "
-        "bare form opens the file-picker dialog)",
-        /*scriptable=*/ true,
-        /*interactive=*/ true,
-    };
 
     commands["restore"] = {
         {{"filename", Completion::Path}},
@@ -843,4 +668,8 @@ void Tui::RegisterCommands() {
         /*prompt_for_missing=*/ true,
         "clone a module under a new name (parts, pins, signals; no connections)",
     };
+
+    // Per-group registrators living in their own files. Keeps each
+    // self-contained concern out of this orchestrator.
+    RegisterExportCommands();
 }
diff --git a/src/tui/commands_export.cpp b/src/tui/commands_export.cpp
new file mode 100644
index 0000000..2fe7f20
--- /dev/null
+++ b/src/tui/commands_export.cpp
@@ -0,0 +1,191 @@
+#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
+                        // (LibreOffice tolerates them but stays portable).
+                        std::string sname = c->name;
+                        for (char &ch : sname)
+                            if (ch == '/' || ch == '\\' || ch == '?' || ch == '*'
+                                || ch == ':' || ch == '[' || ch == ']') ch = '_';
+                        OdsSheet *s = w.add_sheet(sname);
+                        const char *hdr[] = {
+                            "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",
+                            "mixed"};
+                        for (int i = 0; i < 14; ++i) s->set(0, i, hdr[i]);
+                        int row = 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 mixed = (lt != "(NC)" && rt != "(NC)" && lt != rt)
+                                              ? "yes" : "no";
+                            s->set(row, 0,  c->transform_name);
+                            s->set(row, 1,  lm); s->set(row, 2,  lp);
+                            s->set(row, 3,  ln); s->set(row, 4,  ls);
+                            s->set(row, 5,  lt); s->set(row, 6,  lsus);
+                            s->set(row, 7,  rm); s->set(row, 8,  rp);
+                            s->set(row, 9,  rn); s->set(row, 10, rs);
+                            s->set(row, 11, rt); s->set(row, 12, rsus);
+                            s->set(row, 13, mixed);
+                            ++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;
+                }
+
+                // CSV fallback.
+                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,"
+                     "mixed\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 mixed = "no";
+                        if (lt != "(NC)" && rt != "(NC)" && lt != rt) mixed = "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) << ','
+                          << mixed << '\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,
+    };
+}
diff --git a/src/tui/screen_sigtype_modal.cpp b/src/tui/screen_sigtype_modal.cpp
index 7118b65..3319532 100644
--- a/src/tui/screen_sigtype_modal.cpp
+++ b/src/tui/screen_sigtype_modal.cpp
@@ -1,12 +1,71 @@
 #include "tui/tui.hpp"
 
+#include "system/modules.hpp"
+#include "system/signals.hpp"
+#include "system/system.hpp"
+
 #include <ftxui/component/component.hpp>
 #include <ftxui/component/component_options.hpp>
 #include <ftxui/component/event.hpp>
 #include <ftxui/dom/elements.hpp>
 
+#include <exception>
+#include <utility>
+
 using namespace ftxui;
 
+// Lifecycle of the signal-type popup. The Open* and Apply* methods used
+// to live in shell.cpp; moved here so the modal owns all of its logic.
+
+void Tui::OpenSignalTypeDialog(const std::string &mod_name,
+                               const std::string &sig_name) {
+    if (!sys) return;
+    Signal *sig = nullptr;
+    try {
+        Module *m = sys->modules()->get(mod_name);
+        sig = m->signals->get(sig_name);
+    } catch (const std::exception &) { return; }
+
+    sigtype_dialog_mod = mod_name;
+    sigtype_dialog_sig = sig_name;
+    switch (sig->type) {
+    case SignalType::Power:     sigtype_dialog_choice = 0; break;
+    case SignalType::GndShield: sigtype_dialog_choice = 1; break;
+    default:                    sigtype_dialog_choice = 2; break;
+    }
+    sigtype_dialog_open = true;
+}
+
+void Tui::ApplySignalTypeChoice() {
+    sigtype_dialog_open = false;
+    if (!sys) return;
+    SignalType t;
+    switch (sigtype_dialog_choice) {
+    case 0:  t = SignalType::Power;     break;
+    case 1:  t = SignalType::GndShield; break;
+    default: t = SignalType::Other;     break;
+    }
+    Signal *sig = nullptr;
+    try {
+        Module *m = sys->modules()->get(sigtype_dialog_mod);
+        sig = m->signals->get(sigtype_dialog_sig);
+    } catch (const std::exception &) { return; }
+    if (sig->type == t) return;       // no-op, no record
+    sig->type = t;
+    if (in_source) return;
+
+    // Dedup: if the immediately previous recorded line targets the same
+    // signal, replace it so a sequence of toggles collapses to one line.
+    std::string line = "set-signal-type " + sigtype_dialog_mod + " "
+                     + sigtype_dialog_sig + " " + signal_type_name(t);
+    std::string prefix = "set-signal-type " + sigtype_dialog_mod + " "
+                       + sigtype_dialog_sig + " ";
+    if (!recorded.empty() && recorded.back().rfind(prefix, 0) == 0)
+        recorded.back() = std::move(line);
+    else
+        recorded.push_back(std::move(line));
+}
+
 Component Tui::BuildSignalTypeModal() {
     sigtype_dialog_entries = {"power", "gnd", "other"};
 
diff --git a/src/tui/shell.cpp b/src/tui/shell.cpp
index 912aedf..6c52002 100644
--- a/src/tui/shell.cpp
+++ b/src/tui/shell.cpp
@@ -31,55 +31,6 @@ void Tui::BootDispatch(const std::string &raw) {
     screen_idx = 4;
 }
 
-void Tui::OpenSignalTypeDialog(const std::string &mod_name,
-                               const std::string &sig_name) {
-    if (!sys) return;
-    Signal *sig = nullptr;
-    try {
-        Module *m = sys->modules()->get(mod_name);
-        sig = m->signals->get(sig_name);
-    } catch (const std::exception &) { return; }
-
-    sigtype_dialog_mod = mod_name;
-    sigtype_dialog_sig = sig_name;
-    switch (sig->type) {
-    case SignalType::Power:     sigtype_dialog_choice = 0; break;
-    case SignalType::GndShield: sigtype_dialog_choice = 1; break;
-    default:                    sigtype_dialog_choice = 2; break;
-    }
-    sigtype_dialog_open = true;
-}
-
-void Tui::ApplySignalTypeChoice() {
-    sigtype_dialog_open = false;
-    if (!sys) return;
-    SignalType t;
-    switch (sigtype_dialog_choice) {
-    case 0:  t = SignalType::Power;     break;
-    case 1:  t = SignalType::GndShield; break;
-    default: t = SignalType::Other;     break;
-    }
-    Signal *sig = nullptr;
-    try {
-        Module *m = sys->modules()->get(sigtype_dialog_mod);
-        sig = m->signals->get(sigtype_dialog_sig);
-    } catch (const std::exception &) { return; }
-    if (sig->type == t) return;  // no-op, no record
-    sig->type = t;
-    if (in_source) return;
-
-    // Dedup: if the immediately previous recorded line targets the same
-    // signal, replace it so a sequence of toggles collapses to one line.
-    std::string line = "set-signal-type " + sigtype_dialog_mod + " "
-                     + sigtype_dialog_sig + " " + signal_type_name(t);
-    std::string prefix = "set-signal-type " + sigtype_dialog_mod + " "
-                       + sigtype_dialog_sig + " ";
-    if (!recorded.empty() && recorded.back().rfind(prefix, 0) == 0)
-        recorded.back() = std::move(line);
-    else
-        recorded.push_back(std::move(line));
-}
-
 void Tui::Print(const std::string &line) {
     output.push_back(line);
     scroll_offset = 0;  // any new line snaps the view back to the tail
diff --git a/src/tui/tui.hpp b/src/tui/tui.hpp
index 411158e..71e9718 100644
--- a/src/tui/tui.hpp
+++ b/src/tui/tui.hpp
@@ -201,6 +201,9 @@ public:
 private:
     // Lifecycle (commands.cpp)
     void RegisterCommands();
+    // Per-file command-group registrators. Each adds entries to the
+    // `commands` map. Called from RegisterCommands().
+    void RegisterExportCommands();   // commands_export.cpp
 
     // Shell (shell.cpp)
     void Print(const std::string &line);