Split kit and keys; KEYS GEN with MOTIF, 303, TURING, ARP

- genome(seed, salts) now has three parts with their own RNG streams:
  shared (steps, form, swing, arc, layback, fill odds, phase offset),
  kit (density, frame, accent cycle, free snare) and keys (scale/root,
  progression, motif, hocket, bass tone, note lengths, range). ROLL KEYS
  now renews the harmony too; ROLL KIT leaves the keys alone.
- Keys generators share one signature and can fix note lengths:
  MOTIF (the old line), 303 (acid bass, answers in the rests, drone or
  silent pad), TURING (8/16-bit shift register, DRIFT flips bits, 16-bar
  window), ARP (triad/7th arpeggio, roots on kicks).
- Pages: KIT GEN, KEYS GEN; ROLL shows KIT / KEYS; slots keep both gens.
- Flash record v3 (old settings ignored). Bring-up golden checksums updated.
- C port matches; host test and ASan/UBSan pass.

Intended music change: every seed sounds different (genome split, new
generators). Vectors regenerated with npm run vectors; the case grid now
crosses all kit and keys generators, with TURING runs past its window.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

firmware/app/main.c

@@ -29,7 +29,7 @@ static const char *const TRACK_NAME[SB_NT] = { "KICK","KICK 2","SNARE","GHOST","
 static const char *const NOTE_NAME[12] = { "C","C#","D","D#","E","F","F#","G","G#","A","A#","B" };
 static const char *const GEN_NAME[SB_NGEN] = { "EUCLID","SKELETON","SUBDIV","AUTOMATA","AMENIZER" };
 static const int8_t PANEL[12] = { 0, 1, 2, -1,   4, 5, 6, 3,   7, 8, 9, 10 };   /* screen map = button grid; -1 = RUN */
-enum { PG_SEED, PG_GEN, PG_ROOT, PG_SCALE, PG_BPM, PG_SLOT, PG_ROLL, PG_LEARN, NPAGES };
+enum { PG_SEED, PG_GEN, PG_KEYS, PG_ROOT, PG_SCALE, PG_BPM, PG_SLOT, PG_ROLL, PG_LEARN, NPAGES };
 
 static slot_t slots[NSLOTS];
 static sb_state history[16];
@@ -57,7 +57,7 @@ static void set_state(sb_state s){
   hist_sel = 0; mark_dirty();
 }
 static void new_seed(void){ sb_state s = { get_rand_32(), {0, 0} }; set_state(s); }
-static void reroll(int l){ sb_state s = g_live.state; s.salts[l] = (s.salts[l] + 1) & 0xFFFF; set_state(s); msg(l ? "NEW LINE" : "NEW KIT", 700); }
+static void reroll(int l){ sb_state s = g_live.state; s.salts[l] = (s.salts[l] + 1) & 0xFFFF; set_state(s); msg(l ? "NEW KEYS" : "NEW KIT", 700); }
 
 static void apply_on(int tr, int v){ lock(); g_live.on[tr] = (uint8_t)v; unlock(); mark_dirty(); if(!sounds(tr)) send_cmd(CMD_RELEASE_TRACK, tr); }
 static void set_inv(int tr, int v){ lock(); g_live.inv[tr] = (uint8_t)v; unlock(); if(!sounds(tr)) send_cmd(CMD_RELEASE_TRACK, tr); }
@@ -68,6 +68,7 @@ static void enc_turn(int d){
   switch(page){
     case PG_SEED: hist_sel = clampi(hist_sel + d, 0, nhist); break;
     case PG_GEN:  lock(); g_live.gen = (g_live.gen + d + SB_NGEN) % SB_NGEN; unlock(); mark_dirty(); break;
+    case PG_KEYS: lock(); g_live.keys = (g_live.keys + d + SB_NKEYS) % SB_NKEYS; unlock(); mark_dirty(); break;
     case PG_ROOT:  lock(); g_live.root  = (g_live.root  + 1 + d + 13) % 13 - 1; unlock(); mark_dirty(); break;                     /* AUTO, C .. B */
     case PG_SCALE: lock(); g_live.scale = (g_live.scale + 1 + d + SB_NSCALES + 1) % (SB_NSCALES + 1) - 1; unlock(); mark_dirty(); break;   /* AUTO, MAJOR .. LOCRIAN */
     case PG_BPM:  set_bpm(g_live.bpm + d); break;
@@ -88,13 +89,13 @@ static void enc_push(int hold){
       char t[24];
       slots[slot_sel].used = 1; slots[slot_sel].seed = g_live.state.seed;
       slots[slot_sel].salts[0] = g_live.state.salts[0]; slots[slot_sel].salts[1] = g_live.state.salts[1];
-      slots[slot_sel].gen = (uint8_t)g_live.gen; mark_dirty();
+      slots[slot_sel].gen = (uint8_t)g_live.gen; slots[slot_sel].keys = (uint8_t)g_live.keys; mark_dirty();
       snprintf(t, sizeof t, "SAVED S%d", slot_sel + 1); msg(t, 900);
       return;
     }
     if(slots[slot_sel].used){
       sb_state s = { slots[slot_sel].seed, { slots[slot_sel].salts[0], slots[slot_sel].salts[1] } };
-      lock(); g_live.gen = slots[slot_sel].gen; unlock();
+      lock(); g_live.gen = slots[slot_sel].gen; g_live.keys = slots[slot_sel].keys % SB_NKEYS; unlock();
       set_state(s);
     }
   }
@@ -149,15 +150,16 @@ static void screen_text(char *label, char *value){
       if(hist_sel > 0) snprintf(n, sizeof n, " -%d", hist_sel);
       snprintf(l, sizeof l, "SEED%s%s", n, (s->salts[0] || s->salts[1]) ? " *" : "");
       hex8(v, s->seed); break; }
-    case PG_GEN:  strcpy(l, "GENERATOR"); strcpy(v, GEN_NAME[g_live.gen]); break;
+    case PG_GEN:  strcpy(l, "KIT GEN"); strcpy(v, GEN_NAME[g_live.gen]); break;
+    case PG_KEYS: strcpy(l, "KEYS GEN"); strcpy(v, sb_keys_name(g_live.keys)); break;
     case PG_ROOT: case PG_SCALE: {   /* on AUTO, show the seed's own pick */
       sb_genome g; int sc = page == PG_SCALE, x = sc ? g_live.scale : g_live.root;
-      if(x < 0){ sb_genome_make(g_live.state.seed, &g); x = sc ? g.scale : g.root; }
+      if(x < 0){ sb_genome_make(&g_live.state, &g); x = sc ? g.scale : g.root; }
       snprintf(l, sizeof l, "%s%s", sc ? "SCALE" : "ROOT", (sc ? g_live.scale : g_live.root) < 0 ? " AUTO" : "");
       strcpy(v, sc ? sb_scale_name(x) : NOTE_NAME[x]); break; }
     case PG_BPM:  strcpy(l, "TEMPO"); snprintf(v, sizeof v, "%d BPM", g_live.bpm); break;
     case PG_SLOT: snprintf(l, sizeof l, "SLOT %d", slot_sel + 1); if(slots[slot_sel].used) hex8(v, slots[slot_sel].seed); else strcpy(v, "EMPTY"); break;
-    case PG_ROLL: strcpy(l, "RE-ROLL"); strcpy(v, roll_sel ? "LINE" : "KIT"); break;
+    case PG_ROLL: strcpy(l, "RE-ROLL"); strcpy(v, roll_sel ? "KEYS" : "KIT"); break;
     case PG_LEARN: {
       if(learn_mode == 2){ const char *n = TRACK_NAME[learn_tr]; char *o; strcpy(l, "LEARN "); o = l + 6; for(; *n; n++) if(*n != ' ') *o++ = *n; *o = 0; }
       else strcpy(l, "LEARN");