feat: humanize MIDI timing and dynamics with reproducible seeded edits

docs/COMPOSITION_WORKFLOWS.md

@@ -26,3 +26,7 @@ The existing Split clip at cursor command (S) now handles MIDI as well as audio.
 ## Phase 63 — MIDI Clip Consolidation
 
 Edit/Consolidate MIDI clips merges two or more selected MIDI clips on one track. The new clip spans their full bounding range; gaps and overlapping notes remain. Notes outside visible trims are discarded and crossing notes are cropped to audible boundaries. IDs are fresh. Cropped notes start anew, so envelope/phase behavior can change. Audio or cross-track selections reject atomically.
+
+## Phase 64 — Deterministic MIDI Humanization
+
+Edit/MIDI tools/Humanize applies timing variation up to 960 ticks and velocity variation up to 127, using a 32-bit seed and stable note IDs. Repeating from the same original state reproduces results; applying repeatedly accumulates edits. All source notes are affected, including hidden trimmed notes. Timing outside source bounds rejects the entire edit; velocities clamp to 1..127. This is offline editing, not live randomness.

docs/ROADMAP.md

@@ -1587,12 +1587,12 @@ Implemented: transactional consolidation of selected same-track MIDI clips into
 Apply seeded timing and velocity variation to MIDI clip sources with reproducible results, bounds checks and undo.
 
 ### Tasks and acceptance criteria
-- [ ] Implement bounded C99 model/control APIs and accessible GUI commands.
+- [x] Implement bounded C99 model/control APIs and accessible GUI commands.
-- [ ] Preserve transactional errors, history, compatibility and callback safety.
+- [x] Preserve transactional errors, history, compatibility and callback safety.
-- [ ] Verify the feature with automated model/GUI tests and document limitations.
+- [x] Verify the feature with automated model/GUI tests and document limitations.
 
 ### Implementation status
-Planned.
+Implemented: seeded note-ID keyed timing/velocity humanization, independent of selection order. Timing overflow rejects atomically; velocity saturates to MIDI bounds. Core reproducibility/range/rollback and GUI undo tests pass.
 
 ---
 

include/xtc/xtc_editing.h

@@ -46,7 +46,7 @@ xtc_result xtc_project_merge_midi(xtc_project *project,const uint64_t *ids,size_
  * Swing durations stay fixed. LEGATO ends at the next strictly later onset in
  * the same clip/channel (chords stay together), or source end for the last onset.
  * Out-of-source results reject the complete operation. */
-typedef enum { XTC_MIDI_TRANSFORM_SWING, XTC_MIDI_TRANSFORM_GATE, XTC_MIDI_TRANSFORM_LEGATO, XTC_MIDI_TRANSFORM_SCALE, XTC_MIDI_TRANSFORM_VELOCITY } xtc_midi_transform_type;
+typedef enum { XTC_MIDI_TRANSFORM_SWING, XTC_MIDI_TRANSFORM_GATE, XTC_MIDI_TRANSFORM_LEGATO, XTC_MIDI_TRANSFORM_SCALE, XTC_MIDI_TRANSFORM_VELOCITY, XTC_MIDI_TRANSFORM_HUMANIZE } xtc_midi_transform_type;
 typedef struct {
     xtc_midi_transform_type type;
     uint64_t grid;
@@ -54,6 +54,8 @@ typedef struct {
     unsigned int velocity_percent; /* VELOCITY: 0..400, rounded scaling then offset, clamp to 1..127. */
     int velocity_offset; /* -127..127 */
     unsigned int root,scale; /* SCALE: root 0..11 (C..B), scale 0 chromatic, 1 major, 2 natural minor; nearest ties lower. */
+    unsigned int seed; /* HUMANIZE: stable note-ID keyed 32-bit PRNG seed. */
+    unsigned int timing_variation,velocity_variation; /* 0..960 ticks, 0..127 velocity; source overflow rejects, velocity clamps. */
     unsigned int gate_percent; /* GATE: 1..400, rounded length, minimum 1 tick. */
 } xtc_midi_transform;
 xtc_result xtc_project_transform_midi(xtc_project *project,const uint64_t *ids,size_t count,const xtc_midi_transform *edit);

src/gui/main_window.cpp

@@ -331,6 +331,7 @@ MainWindow::MainWindow(bool prompt_unsaved,const char *configuration)
     menu->add("Edit/Nudge selection right",0,[](Fl_Widget *,void *c){static_cast<SequencerWidget *>(c)->nudge_selection(1);},sequencer_);
     menu->add("Edit/Audio tools/Set boundary fades...",0,[](Fl_Widget *,void *c){static_cast<SequencerWidget *>(c)->fades_dialog();},sequencer_);
     menu->add("Edit/Audio tools/Remove boundary fades",0,[](Fl_Widget *,void *c){static_cast<SequencerWidget *>(c)->transform_selection(XTC_CLIPS_FADE,0);},sequencer_);
+    menu->add("Edit/MIDI tools/Humanize...",0,[](Fl_Widget *,void *c){static_cast<SequencerWidget *>(c)->humanize_dialog();},sequencer_);
     menu->add("Edit/MIDI tools/Shape velocities...",0,[](Fl_Widget *,void *c){static_cast<SequencerWidget *>(c)->velocity_dialog();},sequencer_);
     menu->add("Edit/MIDI tools/Correct to scale...",0,[](Fl_Widget *,void *c){static_cast<SequencerWidget *>(c)->scale_dialog();},sequencer_);
     menu->add("Edit/MIDI tools/Note gate...",0,[](Fl_Widget *,void *c){static_cast<SequencerWidget *>(c)->gate_dialog();},sequencer_);

src/gui/sequencer_widget.cpp

@@ -618,6 +618,13 @@ void SequencerWidget::fades_dialog()
     if(!(values>>ticks) || (values>>extra) || ticks<0 || ticks>static_cast<int64_t>(XTC_PROJECT_MAX_TICK)){fl_alert("Enter a valid nonnegative tick length.");return;}
     transform_selection(XTC_CLIPS_FADE,ticks);
 }
+void SequencerWidget::humanize_dialog()
+{
+    const char *input=fl_input("Timing variation ticks (0..960), velocity variation (0..127), seed","12 8 1");if(!input)return;
+    unsigned int timing=0,velocity=0,seed=0;char extra;std::istringstream values(input);
+    if(!(values>>timing>>velocity>>seed) || (values>>extra) || timing>960 || velocity>127){fl_alert("Enter bounded timing/velocity variation and a 32-bit seed.");return;}
+    xtc_midi_transform edit{};edit.type=XTC_MIDI_TRANSFORM_HUMANIZE;edit.timing_variation=timing;edit.velocity_variation=velocity;edit.seed=seed;transform_midi(edit);
+}
 void SequencerWidget::velocity_dialog()
 {
     const char *input=fl_input("Velocity percentage (0..400), then offset (-127..127)","100 0");if(!input)return;

src/gui/sequencer_widget.hpp

@@ -50,6 +50,7 @@ class SequencerWidget : public Fl_Group {
     void gate_dialog();
     void scale_dialog();
     void velocity_dialog();
+    void humanize_dialog();
     void fades_dialog();
     xtc_result repeat_selection(unsigned int copies);
     void repeat_dialog();

src/project/editing.c

@@ -137,8 +137,9 @@ xtc_result xtc_project_transform_midi(xtc_project *p,const uint64_t *ids,size_t
 {
     xtc_project *copy=NULL;size_t i,j,matched=0;xtc_result r=selection_valid(p,ids,count);
     if(r!=XTC_OK)return r;
-    if(!edit || edit->type<XTC_MIDI_TRANSFORM_SWING || edit->type>XTC_MIDI_TRANSFORM_VELOCITY)return XTC_ERR_INVALID_ARGUMENT;
+    if(!edit || edit->type<XTC_MIDI_TRANSFORM_SWING || edit->type>XTC_MIDI_TRANSFORM_HUMANIZE)return XTC_ERR_INVALID_ARGUMENT;
     if(edit->type==XTC_MIDI_TRANSFORM_SWING && (!edit->grid || edit->grid>3840 || edit->swing>100 || edit->strength>100))return XTC_ERR_INVALID_ARGUMENT;
+    if(edit->type==XTC_MIDI_TRANSFORM_HUMANIZE && (edit->timing_variation>960 || edit->velocity_variation>127))return XTC_ERR_INVALID_ARGUMENT;
     if(edit->type==XTC_MIDI_TRANSFORM_GATE && (!edit->gate_percent || edit->gate_percent>400))return XTC_ERR_INVALID_ARGUMENT;
     if(edit->type==XTC_MIDI_TRANSFORM_VELOCITY && (edit->velocity_percent>400 || edit->velocity_offset < -127 || edit->velocity_offset>127))return XTC_ERR_INVALID_ARGUMENT;
     if(edit->type==XTC_MIDI_TRANSFORM_SCALE && (edit->root>11 || edit->scale>2))return XTC_ERR_INVALID_ARGUMENT;
@@ -172,6 +173,16 @@ xtc_result xtc_project_transform_midi(xtc_project *p,const uint64_t *ids,size_t
             int velocity=(int)((n->velocity*edit->velocity_percent+50)/100)+edit->velocity_offset;
             n->velocity=(unsigned int)(velocity<1 ? 1 : velocity>127 ? 127 : velocity);
         }
+        if(edit->type==XTC_MIDI_TRANSFORM_HUMANIZE) {
+            uint32_t random=(uint32_t)(n->id^(n->id>>32))^(uint32_t)edit->seed^UINT32_C(0x9e3779b9);
+            int64_t start;int velocity;
+            random^=random<<13;random^=random>>17;random^=random<<5;
+            start=(int64_t)n->start_tick+(int64_t)(random%(2*edit->timing_variation+1))-(int64_t)edit->timing_variation;
+            random^=random<<13;random^=random>>17;random^=random<<5;
+            velocity=(int)n->velocity+(int)(random%(2*edit->velocity_variation+1))-(int)edit->velocity_variation;
+            if(start<0){r=XTC_ERR_INVALID_ARGUMENT;break;}
+            n->start_tick=(uint64_t)start;n->velocity=(unsigned int)(velocity<1 ? 1 : velocity>127 ? 127 : velocity);
+        }
         if(n->start_tick>=c.source_length_tick || n->length_tick>c.source_length_tick-n->start_tick)r=XTC_ERR_INVALID_ARGUMENT;
     }
     if(r==XTC_OK && !matched)r=XTC_ERR_NOT_FOUND;

tests/integration/test_gui.cpp

@@ -1385,6 +1385,9 @@ int main(int argc, char **argv)
         CHECK(s->select(0,0));CHECK(s->duplicate_selection()==XTC_OK);s->select_all_clips();CHECK(s->merge_midi()==XTC_OK);
         xtc_project_get_counts(s->project(),&tracks,&clips);CHECK(clips==1);
         CHECK(window.undo()==XTC_OK);xtc_project_get_counts(s->project(),&tracks,&clips);CHECK(clips==2);
+        CHECK(s->select(0,0));CHECK(window.open_piano_roll()==XTC_OK);CHECK(window.piano_roll()->add_note(480,240,60)==XTC_OK);
+        xtc_midi_transform human{};human.type=XTC_MIDI_TRANSFORM_HUMANIZE;human.seed=42;human.timing_variation=12;human.velocity_variation=8;
+        CHECK(s->transform_midi(human)==XTC_OK);CHECK(window.undo()==XTC_OK);
         window.do_callback();
     }
     if (failures != 0) return 1;

tests/unit/test_next_daw.c

@@ -111,4 +111,19 @@ static void merge_midi(void)
     assert(xtc_project_get_note(p,1,&note)==XTC_OK && note.start_tick==960 && note.length_tick==240 && note.pitch==67);
     xtc_project_destroy(p);
 }
-int main(void){markers();sections();ripple();duplicate_track();split_midi();merge_midi();puts("Next DAW workflow tests passed.");return 0;}
+static void humanize(void)
+{
+    xtc_project *p=NULL,*q=NULL;uint64_t t,c,n;xtc_note_info a,b;xtc_midi_transform edit={0};
+    assert(xtc_project_create(&p)==XTC_OK && xtc_project_add_track(p,"Track",&t)==XTC_OK);
+    assert(xtc_project_add_midi_clip(p,t,0,1920,&c)==XTC_OK && xtc_project_add_note(p,c,480,120,60,100,0,&n)==XTC_OK);
+    assert(xtc_project_clone(p,&q)==XTC_OK);
+    edit.type=XTC_MIDI_TRANSFORM_HUMANIZE;edit.seed=42;edit.timing_variation=30;edit.velocity_variation=12;
+    assert(xtc_project_transform_midi(p,&c,1,&edit)==XTC_OK && xtc_project_transform_midi(q,&c,1,&edit)==XTC_OK);
+    assert(xtc_project_get_note(p,0,&a)==XTC_OK && xtc_project_get_note(q,0,&b)==XTC_OK && !memcmp(&a,&b,sizeof(a)));
+    assert(a.start_tick>=450 && a.start_tick<=510 && a.velocity>=88 && a.velocity<=112 && a.id==n);
+    assert(xtc_project_edit_note(p,n,0,1920,60,100,0)==XTC_OK);edit.timing_variation=960;
+    assert(xtc_project_transform_midi(p,&c,1,&edit)==XTC_ERR_INVALID_ARGUMENT);
+    assert(xtc_project_get_note(p,0,&a)==XTC_OK && a.start_tick==0 && a.velocity==100);
+    xtc_project_destroy(p);xtc_project_destroy(q);
+}
+int main(void){markers();sections();ripple();duplicate_track();split_midi();merge_midi();humanize();puts("Next DAW workflow tests passed.");return 0;}