feat: plan modern editing phases and add arrangement multi-selection

docs/MODERN_EDITING.md

@@ -0,0 +1,9 @@
+# Modern editing workflows
+
+These control-thread edits preserve project format 15. Session selections,
+clipboard and comparison snapshots are not saved in projects. Audio callbacks
+continue to consume prepared plans; edits use the existing stop/history workflow.
+
+## Phase 47
+
+Shift-click clips to toggle selection; Ctrl+A in the sequencer or Edit/Select all clips selects every clip. Plain clicking replaces the selection. Selection is session UI state; no marquee selection yet.

docs/ROADMAP.md

@@ -1312,6 +1312,171 @@ BUILTIN_DEVICES.md. Application project format is now 15, reading versions 1–1
 
 ---
 
+## Phase 47 — Arrangement Multi-selection
+
+### Goal
+Select clips across tracks with additive selection and Select all; preserve stable IDs across refresh and docking.
+
+### Tasks and acceptance criteria
+- [x] Provide the control/model behavior and accessible GUI commands.
+- [x] Validate bounds and failure rollback; preserve existing project compatibility and callback safety.
+- [x] Test the new workflow and document scope and limitations.
+
+### Implementation status
+Implemented: additive Shift-click selection, Ctrl+A/Select all and selected clip outlines across tracks. Stable IDs survive refresh and panel reparenting. Core build/tests and GUI selection/docking tests pass.
+
+---
+
+## Phase 48 — Transactional Group Editing
+
+### Goal
+Move, duplicate and delete selected clips atomically, preserving relative positions and a single undo step.
+
+### Tasks and acceptance criteria
+- [ ] Provide the control/model behavior and accessible GUI commands.
+- [ ] Validate bounds and failure rollback; preserve existing project compatibility and callback safety.
+- [ ] Test the new workflow and document scope and limitations.
+
+### Implementation status
+Planned.
+
+---
+
+## Phase 49 — Arrangement Clipboard
+
+### Goal
+Copy selected clips into an independent session clipboard and paste at the cursor with fresh IDs, notes and media references.
+
+### Tasks and acceptance criteria
+- [ ] Provide the control/model behavior and accessible GUI commands.
+- [ ] Validate bounds and failure rollback; preserve existing project compatibility and callback safety.
+- [ ] Test the new workflow and document scope and limitations.
+
+### Implementation status
+Planned.
+
+---
+
+## Phase 50 — Repeat Arrangement Patterns
+
+### Goal
+Repeat a selected phrase by its complete bounding span with bounded copy counts and all-or-nothing capacity validation.
+
+### Tasks and acceptance criteria
+- [ ] Provide the control/model behavior and accessible GUI commands.
+- [ ] Validate bounds and failure rollback; preserve existing project compatibility and callback safety.
+- [ ] Test the new workflow and document scope and limitations.
+
+### Implementation status
+Planned.
+
+---
+
+## Phase 51 — Align and Slip Editing
+
+### Goal
+Align selected clip starts to the cursor and slip source offsets without moving timeline boundaries.
+
+### Tasks and acceptance criteria
+- [ ] Provide the control/model behavior and accessible GUI commands.
+- [ ] Validate bounds and failure rollback; preserve existing project compatibility and callback safety.
+- [ ] Test the new workflow and document scope and limitations.
+
+### Implementation status
+Planned.
+
+---
+
+## Phase 52 — MIDI Swing Quantization
+
+### Goal
+Apply bounded swing and quantize strength to source note starts with deterministic rounding and source-bound checks.
+
+### Tasks and acceptance criteria
+- [ ] Provide the control/model behavior and accessible GUI commands.
+- [ ] Validate bounds and failure rollback; preserve existing project compatibility and callback safety.
+- [ ] Test the new workflow and document scope and limitations.
+
+### Implementation status
+Planned.
+
+---
+
+## Phase 53 — MIDI Legato and Gate Tools
+
+### Goal
+Set note gates or extend notes to the next onset on the same channel, preserving IDs and validating all notes before publication.
+
+### Tasks and acceptance criteria
+- [ ] Provide the control/model behavior and accessible GUI commands.
+- [ ] Validate bounds and failure rollback; preserve existing project compatibility and callback safety.
+- [ ] Test the new workflow and document scope and limitations.
+
+### Implementation status
+Planned.
+
+---
+
+## Phase 54 — MIDI Scale Correction
+
+### Goal
+Snap notes to a chosen root and chromatic, major or minor scale with deterministic nearest-pitch ties.
+
+### Tasks and acceptance criteria
+- [ ] Provide the control/model behavior and accessible GUI commands.
+- [ ] Validate bounds and failure rollback; preserve existing project compatibility and callback safety.
+- [ ] Test the new workflow and document scope and limitations.
+
+### Implementation status
+Planned.
+
+---
+
+## Phase 55 — MIDI Velocity Shaping
+
+### Goal
+Apply bounded velocity scaling and offsets to selected MIDI clips, with explicit clipping to valid MIDI velocities.
+
+### Tasks and acceptance criteria
+- [ ] Provide the control/model behavior and accessible GUI commands.
+- [ ] Validate bounds and failure rollback; preserve existing project compatibility and callback safety.
+- [ ] Test the new workflow and document scope and limitations.
+
+### Implementation status
+Planned.
+
+---
+
+## Phase 56 — Batch Audio Fade Tools
+
+### Goal
+Apply symmetric boundary fades or remove fades on selected audio clips, preserving clip gain, media and timing.
+
+### Tasks and acceptance criteria
+- [ ] Provide the control/model behavior and accessible GUI commands.
+- [ ] Validate bounds and failure rollback; preserve existing project compatibility and callback safety.
+- [ ] Test the new workflow and document scope and limitations.
+
+### Implementation status
+Planned.
+
+---
+
+## Phase 57 — Mixer A/B Comparison
+
+### Goal
+Capture and recall two session mixer snapshots by stable track ID, with transactional validation, undo and explicit automation limitations.
+
+### Tasks and acceptance criteria
+- [ ] Provide the control/model behavior and accessible GUI commands.
+- [ ] Validate bounds and failure rollback; preserve existing project compatibility and callback safety.
+- [ ] Test the new workflow and document scope and limitations.
+
+### Implementation status
+Planned.
+
+---
+
 ## Recommended Execution Order
 
 Reorder the phases when the audit reveals a blocking dependency. Do not mark a phase complete merely because code exists: its acceptance criteria must be demonstrated by builds, tests, or documented manual verification.

src/gui/main_window.cpp

@@ -320,6 +320,7 @@ MainWindow::MainWindow(bool prompt_unsaved,const char *configuration)
             (void)static_cast<MainWindow *>(c)->sequencer_->grid(xtc_ui::snap_ticks[value]);
     },this);
     Fl_Group::current(parent);
+    menu->add("Edit/Select all clips",0,[](Fl_Widget *,void *c){static_cast<SequencerWidget *>(c)->select_all_clips();},sequencer_);
     menu->add("Edit/Duplicate clip",FL_CTRL+'d',[](Fl_Widget *, void *c) { (void)static_cast<SequencerWidget *>(c)->duplicate_selection(); },sequencer_);
     menu->add("Edit/Split audio at cursor", 0, [](Fl_Widget *, void *c) { (void)static_cast<SequencerWidget *>(c)->split_selection(); }, sequencer_);
     menu->add("Edit/Audio clip gain and fades", 0, [](Fl_Widget *, void *c) { static_cast<SequencerWidget *>(c)->audio_properties_dialog(); }, sequencer_);

src/gui/sequencer_widget.cpp

@@ -50,6 +50,7 @@ bool SequencerWidget::select(uint64_t track, uint64_t clip)
         xtc_clip_info info{};
         if (xtc_project_find_clip(project_,clip,&info) != XTC_OK || info.track_id != track) return false;
     }
+    selection_.clear();
     track_ = track; clip_ = clip; mode_ = 0; redraw();
     return true;
 }
@@ -59,6 +60,7 @@ void SequencerWidget::set_project(xtc_project *project, bool reset)
     project_ = project;
     if (reset) {
         waves_.clear();
+        selection_.clear();
         track_ = clip_ = UINT64_MAX;
         cursor_ = 0;
         mode_ = 0;
@@ -281,9 +283,9 @@ void SequencerWidget::draw()
             int right = left+std::max(4,static_cast<int>(c.length_tick*static_cast<unsigned int>(scale_)/960U));
             int a = std::max(left,cx), b = std::min(right,cx+cw);
             if (b <= a) continue;
-            fl_color(fl_color_average(color,xtc_ui::background(),c.id == clip_ ? .75f : .45f));
+            fl_color(fl_color_average(color,xtc_ui::background(),clip_selected(c.id) ? .75f : .45f));
             fl_rectf(a,py+5,b-a,46);
-            fl_color(c.id == clip_ ? xtc_ui::text() : color); fl_rect(a,py+5,b-a,46);
+            fl_color(clip_selected(c.id) ? xtc_ui::text() : color); fl_rect(a,py+5,b-a,46);
             fl_push_clip(a+1,py+6,std::max(0,b-a-2),44);
             if (c.midi) {
                 /* Real note positions, pitch and duration; no placeholder waveform. */
@@ -405,6 +407,7 @@ int SequencerWidget::handle(int event)
             return 1;
         xtc_track_info t{};
         xtc_project_get_track(project_, static_cast<size_t>(row), &t);
+        uint64_t previous_clip=clip_;
         track_ = t.id;
         clip_ = UINT64_MAX;
         for (size_t j = clips; j > 0 && Fl::event_x()>=header_left()+header_width_; --j) {
@@ -420,6 +423,10 @@ int SequencerWidget::handle(int event)
                 break;
             }
         }
+        if (Fl::event_state(FL_SHIFT) && clip_ != UINT64_MAX) {
+            uint64_t hit=clip_;clip_=previous_clip;toggle_clip(hit);mode_=0;return 1;
+        }
+        selection_.clear();
         if (Fl::event_button() == FL_LEFT_MOUSE && Fl::event_clicks() && clip_ != UINT64_MAX && original_.midi) {
             mode_ = 0;
             if (open_clip) open_clip(context_);
@@ -490,6 +497,7 @@ int SequencerWidget::handle(int event)
         if (Fl::event_key() == 's') { split_selection(); return 1; }
         if (Fl::event_key() == 'a') { audio_properties_dialog(); return 1; }
     }
+    if (event == FL_KEYDOWN && Fl::event_state(FL_CTRL) && Fl::event_key() == 'a') {select_all_clips();return 1;}
     if (event == FL_KEYDOWN && Fl::event_state(FL_CTRL) && Fl::event_key() == 'd') { duplicate_selection(); return 1; }
     if (event == FL_KEYDOWN && Fl::event_key() == FL_F+2) {
         const char *name = fl_input("Name (1..63 UTF-8 bytes)",""); if (name) rename_selection(name); return 1;
@@ -509,6 +517,32 @@ int SequencerWidget::handle(int event)
     return Fl_Group::handle(event);
 }
 
+std::vector<uint64_t> SequencerWidget::selected_clips() const
+{
+    std::vector<uint64_t> ids;xtc_clip_info c{};
+    for(auto id:selection_)if(xtc_project_find_clip(project_,id,&c)==XTC_OK)ids.push_back(id);
+    if(ids.empty() && clip_!=UINT64_MAX && xtc_project_find_clip(project_,clip_,&c)==XTC_OK)ids.push_back(clip_);
+    return ids;
+}
+bool SequencerWidget::clip_selected(uint64_t id) const
+{
+    return selection_.empty() ? id==clip_ : std::find(selection_.begin(),selection_.end(),id)!=selection_.end();
+}
+bool SequencerWidget::toggle_clip(uint64_t id)
+{
+    xtc_clip_info c{};if(xtc_project_find_clip(project_,id,&c)!=XTC_OK)return false;
+    if(selection_.empty() && clip_!=UINT64_MAX)selection_.push_back(clip_);
+    auto found=std::find(selection_.begin(),selection_.end(),id);
+    if(found==selection_.end())selection_.push_back(id);else selection_.erase(found);
+    clip_=selection_.empty() ? UINT64_MAX : selection_.back();track_=c.track_id;redraw();return true;
+}
+void SequencerWidget::select_all_clips()
+{
+    selection_.clear();size_t tracks=0,clips=0;xtc_project_get_counts(project_,&tracks,&clips);
+    for(size_t i=0;i<clips;++i){xtc_clip_info c{};xtc_project_get_clip(project_,i,&c);selection_.push_back(c.id);}
+    if(!selection_.empty())clip_=selection_.back();
+    redraw();
+}
 xtc_result SequencerWidget::grid(uint64_t ticks)
 {
     if (xtc_ui::snap_index(ticks) < 0) return XTC_ERR_INVALID_ARGUMENT;

src/gui/sequencer_widget.hpp

@@ -32,6 +32,10 @@ class SequencerWidget : public Fl_Group {
     Fl_Choice *instrument_choice(uint64_t track) const;
     void refresh_instruments();
     bool select(uint64_t track, uint64_t clip = UINT64_MAX);
+    bool toggle_clip(uint64_t clip);
+    void select_all_clips();
+    bool clip_selected(uint64_t clip) const;
+    std::vector<uint64_t> selected_clips() const;
     xtc_result duplicate_selection();
     xtc_result split_selection();
     xtc_result audio_properties(float gain, uint64_t fade_in, uint64_t fade_out);
@@ -168,6 +172,7 @@ class SequencerWidget : public Fl_Group {
         std::unique_ptr<xtc_waveform, decltype(&xtc_waveform_destroy)> data{nullptr, xtc_waveform_destroy};
     };
     std::vector<Wave> waves_;
+    std::vector<uint64_t> selection_;
     void draw_waveform(const xtc_clip_info &clip, int left, int top);
     xtc_project *project_;
     Seek seek_;

tests/integration/test_gui.cpp

@@ -1307,6 +1307,16 @@ int main(int argc, char **argv)
         }
         unlink(path.c_str());
     }
+    reset();
+    {
+        MainWindow window(false,"");window.show();CHECK(window.create_track(true)==XTC_OK);
+        auto *s=timeline(&window);uint64_t first=s->selected_clip();CHECK(s->duplicate_selection()==XTC_OK);
+        uint64_t second=s->selected_clip();CHECK(s->toggle_clip(first));CHECK(s->selected_clips().size()==2);
+        CHECK(s->clip_selected(first) && s->clip_selected(second));CHECK(!s->toggle_clip(UINT64_MAX));
+        window.detach_editor(0,true);CHECK(s->selected_clips().size()==2);window.detach_editor(0,false);
+        CHECK(s->toggle_clip(first) && !s->clip_selected(first));s->select_all_clips();CHECK(s->selected_clips().size()==2);
+        window.do_callback();
+    }
     if (failures != 0) return 1;
     std::printf("GUI controls/errors/views/timers/cleanup passed: %u opens, %u closes.\n", opens, closes);
     return 0;