Generic (non-5e) ruleset mode: negative HP, down status, mark dead/revive

New campaign/encounter ruleset toggle: 5e (default, unchanged) vs generic.

Generic mode:
- No death saves (deathSave/stabilize throw)
- Negative HP allowed (no clamp at 0)
- <=0 HP = status 'down' (no pips, no unconscious auto-condition)
- Monster death = dead + inactive (same as 5e)
- markDead button: DM sets dead manually (both modes)
- revive: dead->conscious (generic), dead->stable (5e)

5e mode: zero behavior change.

shared/turn.js:
- applyHpChangeGeneric: negative HP, down status, no death-save logic
- markDead: status dead, monster auto-inactive
- reviveParticipant: ruleset-aware (generic=conscious, 5e=stable)
- deathSave/stabilize: throw in generic
- expandUndo: mark_dead case added

UI (src/App.js):
- CreateCampaignForm + CreateEncounterForm: ruleset radio toggle
- handleCreateCampaign/handleCreateEncounter: store ruleset field
- EncounterManager: fetch campaignDoc for default ruleset inheritance
- DM participant: down/dead labels, Mark Dead button (generic), Revive both
- death-save pips/buttons gated 5e-only
- DisplayView: down label, generic status derivation

Tests: 15 generic cases (turn.generic.test.js). 186 shared total.

src/App.js

@@ -125,6 +125,7 @@ const {
   deathSave: combatDeathSave,
   stabilizeParticipant,
   reviveParticipant,
+  markDead,
   toggleCondition: combatToggleCondition,
   reorderParticipants,
 } = shared;
@@ -448,11 +449,12 @@ function ErrorDisplay({ message, critical = false }) {
 function CreateCampaignForm({ onCreate, onCancel }) {
   const [name, setName] = useState('');
   const [backgroundUrl, setBackgroundUrl] = useState('');
+  const [ruleset, setRuleset] = useState('5e');
 
   const handleSubmit = (e) => {
     e.preventDefault();
     if (name.trim()) {
-      onCreate(name, backgroundUrl);
+      onCreate(name, backgroundUrl, ruleset);
     }
   };
 
@@ -484,6 +486,19 @@ function CreateCampaignForm({ onCreate, onCancel }) {
           className="mt-1 block w-full px-3 py-2 bg-stone-800 border border-stone-700 rounded-md shadow-sm focus:outline-none focus:ring-amber-600 focus:border-amber-600 sm:text-sm text-white"
         />
       </div>
+      <div>
+        <label className="block text-sm font-medium text-stone-300 mb-1">Ruleset</label>
+        <div className="flex gap-4">
+          <label className="flex items-center gap-2 text-sm text-stone-200">
+            <input type="radio" value="5e" checked={ruleset === '5e'} onChange={() => setRuleset('5e')} />
+            D&D 5e (death saves)
+          </label>
+          <label className="flex items-center gap-2 text-sm text-stone-200">
+            <input type="radio" value="generic" checked={ruleset === 'generic'} onChange={() => setRuleset('generic')} />
+            Generic (no death saves, negative HP)
+          </label>
+        </div>
+      </div>
       <div className="flex justify-end space-x-3">
         <button
           type="button"
@@ -503,13 +518,14 @@ function CreateCampaignForm({ onCreate, onCancel }) {
   );
 }
 
-function CreateEncounterForm({ onCreate, onCancel }) {
+function CreateEncounterForm({ onCreate, onCancel, defaultRuleset = '5e' }) {
   const [name, setName] = useState('');
+  const [ruleset, setRuleset] = useState(defaultRuleset);
 
   const handleSubmit = (e) => {
     e.preventDefault();
     if (name.trim()) {
-      onCreate(name);
+      onCreate(name, ruleset);
     }
   };
 
@@ -528,6 +544,19 @@ function CreateEncounterForm({ onCreate, onCancel }) {
           required
         />
       </div>
+      <div>
+        <label className="block text-sm font-medium text-stone-300 mb-1">Ruleset</label>
+        <div className="flex gap-4">
+          <label className="flex items-center gap-2 text-sm text-stone-200">
+            <input type="radio" value="5e" checked={ruleset === '5e'} onChange={() => setRuleset('5e')} />
+            D&D 5e (death saves)
+          </label>
+          <label className="flex items-center gap-2 text-sm text-stone-200">
+            <input type="radio" value="generic" checked={ruleset === 'generic'} onChange={() => setRuleset('generic')} />
+            Generic (no death saves, negative HP)
+          </label>
+        </div>
+      </div>
       <div className="flex justify-end space-x-3">
         <button
           type="button"
@@ -1153,6 +1182,15 @@ function ParticipantManager({ encounter, encounterPath, campaignCharacters, camp
     }
   };
 
+  const handleMarkDead = async (participantId) => {
+    if (!db) return;
+    try {
+      await markDead(encounter, participantId, buildCtx(encounterPath));
+    } catch (err) {
+      showToast(err.message);
+    }
+  };
+
   const handleCritDamage = async (participantId) => {
     if (!db) return;
     try {
@@ -1414,14 +1452,18 @@ function ParticipantManager({ encounter, encounterPath, campaignCharacters, camp
             const isCurrentTurn = encounter.isStarted && p.id === encounter.currentTurnParticipantId;
             const isDraggable = (!encounter.isStarted || encounter.isPaused) && tiedInitiatives.includes(Number(p.initiative));
             const participantDisplayType = p.type === 'npc' ? 'NPC' : (p.type === 'monster' ? 'Monster' : 'Character');
-            const hasDeathSaves = p.type === 'character' || p.type === 'npc';
+            const isGeneric = (encounter.ruleset || '5e') === 'generic';
+            const hasDeathSaves = !isGeneric && (p.type === 'character' || p.type === 'npc');
 
             let bgColor = p.type === 'character' ? 'bg-indigo-950' : 'bg-[#8e351c]';
             if (isCurrentTurn && !encounter.isPaused) bgColor = 'bg-green-600';
 
-            const participantStatus = p.status || (p.currentHp === 0 ? (p.type === 'monster' ? 'dead' : 'dying') : 'conscious');
-            const isZeroHp = p.currentHp === 0;
+            const participantStatus = p.status || (isGeneric
+              ? (p.currentHp <= 0 ? 'down' : 'conscious')
+              : (p.currentHp === 0 ? (p.type === 'monster' ? 'dead' : 'dying') : 'conscious'));
+            const isZeroHp = p.currentHp <= 0;
             const isDead = participantStatus === 'dead';
+            const isDown = participantStatus === 'down';
 
             return (
               <li
@@ -1452,6 +1494,7 @@ function ParticipantManager({ encounter, encounterPath, campaignCharacters, camp
                       )}
                       {hasDeathSaves && participantStatus === 'dying' && <span className="ml-2 text-xs text-red-300 font-semibold animate-pulse">(Dying)</span>}
                       {hasDeathSaves && participantStatus === 'stable' && (p.conditions || []).includes('unconscious') && <span className="ml-2 text-xs text-emerald-300 font-semibold">(Unconscious)</span>}
+                      {isDown && <span className="ml-2 text-xs text-red-300 font-semibold animate-pulse">(Down)</span>}
                       {isDead && <span className="ml-2 px-2 py-0.5 rounded bg-red-950 border border-red-500 text-red-200 text-xs font-bold">DEAD</span>}
                     </p>
                     <div className={`text-sm ${isCurrentTurn && !encounter.isPaused ? 'text-green-100' : 'text-stone-200'} flex items-center gap-2`}>
@@ -1477,11 +1520,17 @@ function ParticipantManager({ encounter, encounterPath, campaignCharacters, camp
                     </div>
                     
                     {participantStatus === 'dead' && (
-                      <button onClick={() => handleRevive(p.id)} className="mt-2 inline-flex items-center gap-1 self-start px-2.5 py-1 text-xs rounded bg-emerald-800 hover:bg-emerald-700 text-white" title="Revive to 0 HP, stable and unconscious">
+                      <button onClick={() => handleRevive(p.id)} className="mt-2 inline-flex items-center gap-1 self-start px-2.5 py-1 text-xs rounded bg-emerald-800 hover:bg-emerald-700 text-white" title="Revive (clear dead status)">
                         <HeartPulse size={14} /> Revive
                       </button>
                     )}
 
+                    {isGeneric && !isDead && (
+                      <button onClick={() => handleMarkDead(p.id)} className="mt-2 inline-flex items-center gap-1 self-start px-2.5 py-1 text-xs rounded bg-red-900 hover:bg-red-800 text-white" title="Mark dead">
+                        <HeartCrack size={14} /> Mark Dead
+                      </button>
+                    )}
+
                     {hasDeathSaves && participantStatus === 'stable' && (
                       <div className="mt-2 text-xs text-emerald-300/80 italic">Stable — regains 1 HP after 1d4 hours</div>
                     )}
@@ -1950,6 +1999,7 @@ function EncounterManager({ campaignId, initialActiveEncounterId, campaignCharac
     campaignId ? getPath.encounters(campaignId) : null
   );
   const { data: activeDisplayInfo } = useFirestoreDocument(getPath.activeDisplay());
+  const { data: campaignDoc } = useFirestoreDocument(campaignId ? getPath.campaign(campaignId) : null);
 
   const [encounters, setEncounters] = useState([]);
   const [selectedEncounterId, setSelectedEncounterId] = useState(null);
@@ -1992,7 +2042,7 @@ function EncounterManager({ campaignId, initialActiveEncounterId, campaignCharac
     }
   }, [campaignId, initialActiveEncounterId, activeDisplayInfo, encounters]);
 
-  const handleCreateEncounter = async (name) => {
+  const handleCreateEncounter = async (name, ruleset = '5e') => {
     if (!db || !name.trim() || !campaignId) return;
 
     const newEncounterId = generateId();
@@ -2005,7 +2055,8 @@ function EncounterManager({ campaignId, initialActiveEncounterId, campaignCharac
         round: 0,
         currentTurnParticipantId: null,
         isStarted: false,
-        isPaused: false
+        isPaused: false,
+        ruleset: ruleset || '5e',
       });
 
       setShowCreateModal(false);
@@ -2153,8 +2204,10 @@ function EncounterManager({ campaignId, initialActiveEncounterId, campaignCharac
         {showCreateModal && (
           <Modal onClose={() => setShowCreateModal(false)} title="Create New Encounter">
             <CreateEncounterForm
+              key={campaignId}
               onCreate={handleCreateEncounter}
               onCancel={() => setShowCreateModal(false)}
+              defaultRuleset={campaignDoc?.ruleset || '5e'}
             />
           </Modal>
         )}
@@ -2283,7 +2336,7 @@ function AdminView({ userId }) {
     }
   }, [initialActiveInfo, campaignsWithDetails, selectedCampaignId]);
 
-  const handleCreateCampaign = async (name, backgroundUrl) => {
+  const handleCreateCampaign = async (name, backgroundUrl, ruleset = '5e') => {
     if (!db || !name.trim()) return;
 
     const newCampaignId = generateId();
@@ -2295,6 +2348,7 @@ function AdminView({ userId }) {
         ownerId: userId,
         createdAt: new Date().toISOString(),
         players: [],
+        ruleset: ruleset || '5e',
       });
 
       setShowCreateModal(false);
@@ -2478,6 +2532,12 @@ function AdminView({ userId }) {
                     >
                       <Trash2 size={14} className="mr-1" /> Delete
                     </button>
+                    <span
+                      className={`absolute bottom-2 right-2 z-20 px-2 py-0.5 rounded text-xs font-bold tracking-wide ${campaign.ruleset === 'generic' ? 'bg-purple-900/80 text-purple-200 border border-purple-500' : 'bg-amber-900/80 text-amber-200 border border-amber-500'}`}
+                      title={campaign.ruleset === 'generic' ? 'Generic ruleset' : 'D&D 5e ruleset'}
+                    >
+                      {campaign.ruleset === 'generic' ? 'GEN' : '5e'}
+                    </span>
                   </div>
                 </div>
               );
@@ -2847,8 +2907,9 @@ function DisplayView() {
 
         <div className="space-y-4 max-w-3xl mx-auto">
           {participantsToRender.map(p => {
-            const status = p.status || (p.currentHp === 0 ? 'dying' : 'conscious');
-            const isZeroHp = p.currentHp === 0;
+            const isGeneric = (activeEncounterData.ruleset || '5e') === 'generic';
+            const status = p.status || (isGeneric ? (p.currentHp <= 0 ? 'down' : 'conscious') : (p.currentHp === 0 ? 'dying' : 'conscious'));
+            const isZeroHp = p.currentHp <= 0;
             let participantBgColor = p.type === 'monster' || p.type === 'npc'
               ? 'bg-[#8e351c]'
               : 'bg-indigo-950';
@@ -2882,6 +2943,7 @@ function DisplayView() {
                     )}
                     {status === 'dying' && <span className="text-red-300 text-lg ml-2">(Dying)</span>}
                     {status === 'stable' && (p.conditions || []).includes('unconscious') && <span className="text-emerald-300 text-lg ml-2">(Unconscious)</span>}
+                    {status === 'down' && <span className="text-red-300 text-lg ml-2 animate-pulse">(Down)</span>}
                     {status === 'dead' && <span className="text-red-300 text-lg ml-2">(Dead)</span>}
                   </h3>
                   <span