feat: crimson metronome lends ½ heart, repaid on a clean room clear

js/items.js

@@ -94,7 +94,7 @@ const ITEMS = {
   butchersoath:  { name: "Butcher's Oath",   desc: '+80% damage, but max HP set to 2', rarity: 'legendary', cap: 1, apply: (s, p) => { s.dmgMul *= 1.8; s.maxHp = Math.min(s.maxHp, 2); p.hp = Math.min(p.hp, s.maxHp); } },
   secondskin:    { name: 'Second Skin',      desc: 'Revive once per floor at ½ heart', rarity: 'legendary', cap: 1, apply: s => { s.secondSkin += 1; } },
   twinsidearm:   { name: 'Twin Sidearm',     desc: 'Bone Popper double-taps; specials burn 2× ammo', rarity: 'legendary', cap: 1, apply: s => { s.twinSidearm += 1; } },
-  crimsonmetronome:{ name: 'Crimson Metronome', desc: '+60% fire rate; every 8th shot costs ½ heart', rarity: 'legendary', cap: 1, apply: s => { s.rateMul *= 1.6; s.crimsonMetronome += 1; } },
+  crimsonmetronome:{ name: 'Crimson Metronome', desc: '+60% fire rate; every 8th shot lends ½ heart, repaid if you clear the room clean', rarity: 'legendary', cap: 1, apply: s => { s.rateMul *= 1.6; s.crimsonMetronome += 1; } },
   abattoirengine:{ name: 'Abattoir Engine',  desc: 'Pressure rises 2× faster; score and luck ×1.5', rarity: 'legendary', cap: 1, apply: s => { s.abattoirEngine += 1; s.luck += 0.5; } },
   gorecrown:     { name: 'Gore Crown',       desc: 'Free nova on every kill, −25% damage', rarity: 'legendary', cap: 1, apply: s => { s.goreCrown += 1; s.dmgMul *= 0.75; } },
   thousandteeth: { name: 'Thousand Teeth',   desc: '+6 shards that can crit, −40% base bullet damage', rarity: 'legendary', cap: 1, apply: s => { s.thousandTeeth += 1; s.dmgMul *= 0.6; } },

js/player.js

@@ -31,6 +31,7 @@ function initPlayer() {
     animT: 0, attackT: 0, actionT: 0, hitT: 0, deathT: 0,
     weapon: { id: 'bonepopper', ammo: Infinity },
     holstered: null,   // a special weapon set aside while the pistol is out
+    metronomeTmp: 0,   // ½-hearts lent by Crimson Metronome, repaid on a clean clear
     level: 1, xp: 0,
     items: {},         // iid -> quality tier (1..3)
     perks: [],         // perk ids drafted this run, in grant order
@@ -155,10 +156,16 @@ function updatePlayer(dt) {
         p.choirCount = (p.choirCount || 0) + 1;
         if (p.choirCount >= 4) { p.choirCount = 0; fireWeapon(p, w); }
       }
-      // Crimson Metronome: every 8th shot costs ½ heart
+      // Crimson Metronome: every 8th shot lends ½ heart, repaid when the room clears clean
       if (st.crimsonMetronome > 0) {
         p.metronomeCount = (p.metronomeCount || 0) + 1;
-        if (p.metronomeCount >= 8) { p.metronomeCount = 0; p.hp = Math.max(0.5, p.hp - 1); spawnText(p.x, p.y - 14, '-½', '#e2472f'); }
+        if (p.metronomeCount >= 8) {
+          p.metronomeCount = 0;
+          const loss = Math.min(1, Math.max(0, p.hp - 0.5));
+          p.hp = Math.max(0.5, p.hp - 1);
+          p.metronomeTmp += loss; // on loan: restored by a clean room clear
+          spawnText(p.x, p.y - 14, '-½', '#e2472f');
+        }
       }
       p.recoil = Math.min(1, p.recoil + (w.behavior === 'slam' ? 1 : 0.45));
       p.muzzleT = 0.07;

js/rooms.js

@@ -88,6 +88,7 @@ function enterRoom(gx, gy) {
   G.roomLayerKey = '';
   G.roomDamaged = false;
   G.roomEnterT = G.time;
+  if (G.player) G.player.metronomeTmp = 0; // fresh per-room Crimson-Metronome loan ledger
 
   const room = G.rooms[roomKey(gx, gy)];
   G.cur = room;
@@ -221,6 +222,13 @@ function recordRoomClear(room) {
   }
   // active items charge on room clears: +1 per combat room, +2 per boss
   const p = G.player;
+  // Crimson Metronome: a ½-heart loan is repaid when the room clears clean
+  if (!G.roomDamaged && p.metronomeTmp > 0) {
+    const back = Math.min(p.metronomeTmp, p.stats.maxHp - p.hp);
+    p.hp += back;
+    p.metronomeTmp = 0;
+    if (back > 0) spawnText(p.x, p.y - 26, 'LOAN REPAID +' + back, '#d98991');
+  }
   if (p && p.active) {
     const a = ACTIVES[p.active.iid];
     if (a) {