Add bulk fill and staggered retrofit at campus/cluster level

Campus level: "Fill All DCs" instantly fills all operational DCs with
selected SKU in one click. "Retrofit Campus" queues a staggered retrofit
with configurable concurrency (1/10%/25%/custom) so only a fraction of
DCs go offline at a time, preserving capacity during the upgrade.

Cluster level: "Fill All DCs" fills across all campuses in one action.

The game engine automatically advances the retrofit queue each tick,
promoting pending DCs as active ones complete.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/src/pages/InfrastructurePage.tsx

@@ -5,10 +5,11 @@ import {
   Rocket, Clock, Lock, Cpu,
   Activity, DollarSign, Globe, Building2, Layers,
   Network, ArrowLeft, RefreshCw, ChevronDown,
+  X, CheckCircle,
 } from 'lucide-react';
 import { TutorialHint } from '@/components/game/TutorialHint';
 import { ConfirmModal } from '@/components/common/ConfirmModal';
-import { useGameStore, type InfraNav } from '@/store';
+import { useGameStore, type InfraNav, computeFillForDC } from '@/store';
 import {
   formatMoney, formatNumber, formatPercent,
   LOCATION_CONFIGS, DC_TIER_CONFIGS, RACK_SKU_CONFIGS,
@@ -337,17 +338,132 @@ function BuildClusterModal({ onClose }: { onClose: () => void }) {
   );
 }
 
+// ─── Cluster Fill All Modal ─────────────────────────────────────
+
+function ClusterFillAllModal({ cluster, money, era, research, onConfirm, onClose }: {
+  cluster: Cluster;
+  money: number;
+  era: Era;
+  research: string[];
+  onConfirm: (skuId: RackSkuId) => void;
+  onClose: () => void;
+}) {
+  const availableSkus = Object.values(RACK_SKU_CONFIGS).filter(s => {
+    if (ERA_ORDER.indexOf(era) < ERA_ORDER.indexOf(s.era)) return false;
+    if (s.requiredResearch && !research.includes(s.requiredResearch)) return false;
+    return true;
+  });
+
+  const allDCs = cluster.campuses.flatMap(c => c.dataCenters);
+  const mostCommonSku = useMemo(() => {
+    const counts: Record<string, number> = {};
+    for (const dc of allDCs) {
+      if (dc.rackSkuId) counts[dc.rackSkuId] = (counts[dc.rackSkuId] || 0) + 1;
+    }
+    const entries = Object.entries(counts);
+    return entries.length > 0 ? entries.sort((a, b) => b[1] - a[1])[0][0] as RackSkuId : availableSkus[0]?.id ?? null;
+  }, [allDCs, availableSkus]);
+
+  const [selectedSku, setSelectedSku] = useState<RackSkuId | null>(mostCommonSku);
+
+  const preview = useMemo(() => {
+    if (!selectedSku) return { campuses: [], totalQty: 0, totalCost: 0 };
+    let remaining = money;
+    const campuses = cluster.campuses.map(campus => {
+      if (campus.status !== 'operational') return { campus, dcs: [], totalQty: 0, totalCost: 0 };
+      const dcs = campus.dataCenters.map(dc => {
+        const { qty, cost } = computeFillForDC(dc, selectedSku, remaining);
+        if (qty > 0) remaining -= cost;
+        return { dc, qty, cost };
+      });
+      return { campus, dcs, totalQty: dcs.reduce((s, d) => s + d.qty, 0), totalCost: dcs.reduce((s, d) => s + d.cost, 0) };
+    });
+    return {
+      campuses,
+      totalQty: campuses.reduce((s, c) => s + c.totalQty, 0),
+      totalCost: campuses.reduce((s, c) => s + c.totalCost, 0),
+    };
+  }, [selectedSku, money, cluster.campuses]);
+
+  const fillableDCCount = preview.campuses.reduce((s, c) => s + c.dcs.filter(d => d.qty > 0).length, 0);
+
+  return (
+    <div className="fixed inset-0 bg-black/60 flex items-center justify-center z-50" onClick={onClose}>
+      <div className="bg-surface-900 border border-surface-700 rounded-xl p-6 max-w-lg w-full mx-4 shadow-2xl max-h-[80vh] flex flex-col" onClick={e => e.stopPropagation()}>
+        <h3 className="text-lg font-bold mb-4 flex items-center gap-2"><Rocket size={18} className="text-accent" /> Fill All DCs — {cluster.name}</h3>
+
+        <div className="space-y-4 overflow-y-auto flex-1 min-h-0">
+          <div>
+            <label className="text-xs text-surface-400 mb-2 block">Rack SKU</label>
+            <div className="space-y-1.5">
+              {availableSkus.map(s => (
+                <label key={s.id} className={`flex items-center gap-3 p-2.5 rounded-lg cursor-pointer border text-sm ${selectedSku === s.id ? 'border-accent bg-accent/10' : 'border-surface-600 hover:border-surface-500'}`}>
+                  <input type="radio" name="clusterFillSku" checked={selectedSku === s.id} onChange={() => setSelectedSku(s.id)} className="accent-accent" />
+                  <span className="font-medium">{s.name}</span>
+                  <span className="text-xs text-surface-400 ml-auto">{formatMoney(s.baseCost)}/rack</span>
+                </label>
+              ))}
+            </div>
+          </div>
+
+          {selectedSku && (
+            <div>
+              <label className="text-xs text-surface-400 mb-2 block">Preview by campus</label>
+              <div className="space-y-2 max-h-48 overflow-y-auto">
+                {preview.campuses.map(({ campus, totalQty, totalCost }) => (
+                  <div key={campus.id} className="flex items-center justify-between text-xs px-2 py-1.5 rounded bg-surface-800">
+                    <span className="truncate flex-1 mr-2">{campus.name} ({campus.dataCenters.length} DCs)</span>
+                    {totalQty > 0 ? (
+                      <span className="text-green-400 font-mono shrink-0">+{totalQty} racks ({formatMoney(totalCost)})</span>
+                    ) : (
+                      <span className="text-surface-500 shrink-0">No change</span>
+                    )}
+                  </div>
+                ))}
+              </div>
+            </div>
+          )}
+
+          <div className="bg-surface-800 rounded-lg p-3 text-sm space-y-1">
+            <div className="flex justify-between"><span className="text-surface-400">Total racks:</span><span className="font-mono">{formatNumber(preview.totalQty)}</span></div>
+            <div className="flex justify-between"><span className="text-surface-400">Total cost:</span><span className="font-mono">{formatMoney(preview.totalCost)}</span></div>
+            <div className="flex justify-between"><span className="text-surface-400">Remaining budget:</span><span className="font-mono">{formatMoney(money - preview.totalCost)}</span></div>
+          </div>
+        </div>
+
+        <div className="flex gap-3 mt-4">
+          <button onClick={onClose} className="flex-1 bg-surface-700 hover:bg-surface-600 rounded-lg py-2 text-sm">Cancel</button>
+          <button
+            onClick={() => selectedSku && onConfirm(selectedSku)}
+            disabled={!selectedSku || preview.totalQty === 0}
+            className="flex-1 bg-accent hover:bg-accent-dark disabled:opacity-50 disabled:cursor-not-allowed text-white rounded-lg py-2 text-sm font-medium">
+            Fill {fillableDCCount} DCs ({formatNumber(preview.totalQty)} racks, {formatMoney(preview.totalCost)})
+          </button>
+        </div>
+      </div>
+    </div>
+  );
+}
+
 // ─── Cluster Detail View ────────────────────────────────────────
 
 function ClusterDetailView({ clusterId }: { clusterId: string }) {
   const cluster = useGameStore((s) => s.infrastructure.clusters.find(c => c.id === clusterId));
   const setNav = useGameStore((s) => s.setInfraNav);
+  const fillCluster = useGameStore((s) => s.fillClusterToCapacity);
+  const money = useGameStore((s) => s.economy.money);
+  const era = useGameStore((s) => s.meta.currentEra);
+  const research = useGameStore((s) => s.research.completedResearch);
   const [showBuild, setShowBuild] = useState(false);
+  const [showFillAll, setShowFillAll] = useState(false);
 
   if (!cluster) return <div className="text-surface-400">Cluster not found.</div>;
 
   const location = LOCATION_CONFIGS[cluster.locationId];
 
+  const allDCs = cluster.campuses.flatMap(c => c.dataCenters);
+  const hasOperationalDCs = allDCs.some(dc => dc.status === 'operational');
+
   return (
     <div className="space-y-6">
       <div className="flex items-center justify-between">
@@ -358,10 +474,18 @@ function ClusterDetailView({ clusterId }: { clusterId: string }) {
             <p className="text-sm text-surface-400">{location.name} — {location.energyCostMultiplier}x energy cost</p>
           </div>
         </div>
-        <button onClick={() => setShowBuild(true)}
+        <div className="flex gap-2">
-          className="flex items-center gap-1.5 bg-accent hover:bg-accent-dark text-white rounded-lg px-4 py-2 text-sm font-medium">
+          {hasOperationalDCs && (
-          <Plus size={16} /> New Campus
+            <button onClick={() => setShowFillAll(true)}
-        </button>
+              className="flex items-center gap-1.5 bg-surface-700 hover:bg-surface-600 text-white rounded-lg px-3 py-2 text-sm">
+              <Rocket size={14} /> Fill All DCs
+            </button>
+          )}
+          <button onClick={() => setShowBuild(true)}
+            className="flex items-center gap-1.5 bg-accent hover:bg-accent-dark text-white rounded-lg px-4 py-2 text-sm font-medium">
+            <Plus size={16} /> New Campus
+          </button>
+        </div>
       </div>
 
       {cluster.campuses.length === 0 && (
@@ -383,6 +507,9 @@ function ClusterDetailView({ clusterId }: { clusterId: string }) {
                 {campus.status === 'constructing' && (
                   <span className="text-xs bg-amber-500/20 text-amber-400 px-2 py-0.5 rounded">Building...</span>
                 )}
+                {campus.retrofitQueue && (
+                  <span className="text-xs bg-violet-500/20 text-violet-400 px-2 py-0.5 rounded">Retrofitting</span>
+                )}
               </div>
               <ChevronRight size={16} className="text-surface-400" />
             </div>
@@ -416,6 +543,17 @@ function ClusterDetailView({ clusterId }: { clusterId: string }) {
       </div>
 
       {showBuild && <BuildCampusModal clusterId={clusterId} onClose={() => setShowBuild(false)} />}
+
+      {showFillAll && (
+        <ClusterFillAllModal
+          cluster={cluster}
+          money={money}
+          era={era}
+          research={research}
+          onConfirm={(skuId) => { fillCluster(clusterId, skuId); setShowFillAll(false); }}
+          onClose={() => setShowFillAll(false)}
+        />
+      )}
     </div>
   );
 }
@@ -487,7 +625,283 @@ function BuildCampusModal({ clusterId, onClose }: { clusterId: string; onClose:
   );
 }
 
-// ─── Campus Detail View ─────────────────────────────────────────
+// ─── Campus Bulk Action Components ─────────────────────────────
+
+function FillAllDCsModal({ campus, money, era, research, onConfirm, onClose }: {
+  campus: Campus;
+  money: number;
+  era: Era;
+  research: string[];
+  onConfirm: (skuId: RackSkuId) => void;
+  onClose: () => void;
+}) {
+  const availableSkus = Object.values(RACK_SKU_CONFIGS).filter(s => {
+    if (ERA_ORDER.indexOf(era) < ERA_ORDER.indexOf(s.era)) return false;
+    if (s.requiredResearch && !research.includes(s.requiredResearch)) return false;
+    return true;
+  });
+
+  const mostCommonSku = useMemo(() => {
+    const counts: Record<string, number> = {};
+    for (const dc of campus.dataCenters) {
+      if (dc.rackSkuId) counts[dc.rackSkuId] = (counts[dc.rackSkuId] || 0) + 1;
+    }
+    const entries = Object.entries(counts);
+    return entries.length > 0 ? entries.sort((a, b) => b[1] - a[1])[0][0] as RackSkuId : availableSkus[0]?.id ?? null;
+  }, [campus.dataCenters, availableSkus]);
+
+  const [selectedSku, setSelectedSku] = useState<RackSkuId | null>(mostCommonSku);
+
+  const preview = useMemo(() => {
+    if (!selectedSku) return { dcs: [], totalQty: 0, totalCost: 0 };
+    let remaining = money;
+    const dcs = campus.dataCenters.map(dc => {
+      if (dc.status !== 'operational') return { dc, qty: 0, cost: 0, reason: dc.status === 'constructing' ? 'Constructing' : 'Retrofitting' as string | null };
+      if (dc.status === 'operational' && dc.rackSkuId && dc.rackSkuId !== selectedSku) return { dc, qty: 0, cost: 0, reason: `Different SKU (${RACK_SKU_CONFIGS[dc.rackSkuId].name})` };
+      const { qty, cost } = computeFillForDC(dc, selectedSku, remaining);
+      if (qty === 0) {
+        const tierConfig = DC_TIER_CONFIGS[dc.tier];
+        const maxCompute = maxComputeRacks(tierConfig.rackSlots);
+        const pipelineCount = dc.deploymentCohorts.filter(c => c.stage !== 'decommission').reduce((sum, c) => sum + c.count, 0);
+        const isFull = maxCompute - (dc.computeRacksOnline + pipelineCount) <= 0;
+        return { dc, qty: 0, cost: 0, reason: isFull ? 'Already full' : 'No budget' };
+      }
+      remaining -= cost;
+      return { dc, qty, cost, reason: null };
+    });
+    return { dcs, totalQty: dcs.reduce((s, d) => s + d.qty, 0), totalCost: dcs.reduce((s, d) => s + d.cost, 0) };
+  }, [selectedSku, money, campus.dataCenters]);
+
+  const fillableDCCount = preview.dcs.filter(d => d.qty > 0).length;
+
+  return (
+    <div className="fixed inset-0 bg-black/60 flex items-center justify-center z-50" onClick={onClose}>
+      <div className="bg-surface-900 border border-surface-700 rounded-xl p-6 max-w-lg w-full mx-4 shadow-2xl max-h-[80vh] flex flex-col" onClick={e => e.stopPropagation()}>
+        <h3 className="text-lg font-bold mb-4 flex items-center gap-2"><Rocket size={18} className="text-accent" /> Fill All DCs</h3>
+
+        <div className="space-y-4 overflow-y-auto flex-1 min-h-0">
+          <div>
+            <label className="text-xs text-surface-400 mb-2 block">Rack SKU</label>
+            <div className="space-y-1.5">
+              {availableSkus.map(s => (
+                <label key={s.id} className={`flex items-center gap-3 p-2.5 rounded-lg cursor-pointer border text-sm ${selectedSku === s.id ? 'border-accent bg-accent/10' : 'border-surface-600 hover:border-surface-500'}`}>
+                  <input type="radio" name="fillSku" checked={selectedSku === s.id} onChange={() => setSelectedSku(s.id)} className="accent-accent" />
+                  <span className="font-medium">{s.name}</span>
+                  <span className="text-xs text-surface-400 ml-auto">{formatMoney(s.baseCost)}/rack</span>
+                </label>
+              ))}
+            </div>
+          </div>
+
+          {selectedSku && (
+            <div>
+              <label className="text-xs text-surface-400 mb-2 block">Preview ({fillableDCCount} of {campus.dataCenters.length} DCs)</label>
+              <div className="space-y-1 max-h-48 overflow-y-auto">
+                {preview.dcs.map(({ dc, qty, cost, reason }) => (
+                  <div key={dc.id} className="flex items-center justify-between text-xs px-2 py-1.5 rounded bg-surface-800">
+                    <span className="truncate flex-1 mr-2">{dc.name}</span>
+                    {reason ? (
+                      <span className="text-surface-500 shrink-0">{reason}</span>
+                    ) : (
+                      <span className="text-green-400 font-mono shrink-0">+{qty} racks ({formatMoney(cost)})</span>
+                    )}
+                  </div>
+                ))}
+              </div>
+            </div>
+          )}
+
+          <div className="bg-surface-800 rounded-lg p-3 text-sm space-y-1">
+            <div className="flex justify-between"><span className="text-surface-400">Total racks:</span><span className="font-mono">{formatNumber(preview.totalQty)}</span></div>
+            <div className="flex justify-between"><span className="text-surface-400">Total cost:</span><span className="font-mono">{formatMoney(preview.totalCost)}</span></div>
+            <div className="flex justify-between"><span className="text-surface-400">Remaining budget:</span><span className="font-mono">{formatMoney(money - preview.totalCost)}</span></div>
+          </div>
+        </div>
+
+        <div className="flex gap-3 mt-4">
+          <button onClick={onClose} className="flex-1 bg-surface-700 hover:bg-surface-600 rounded-lg py-2 text-sm">Cancel</button>
+          <button
+            onClick={() => selectedSku && onConfirm(selectedSku)}
+            disabled={!selectedSku || preview.totalQty === 0}
+            className="flex-1 bg-accent hover:bg-accent-dark disabled:opacity-50 disabled:cursor-not-allowed text-white rounded-lg py-2 text-sm font-medium">
+            Fill {fillableDCCount} DCs ({formatNumber(preview.totalQty)} racks, {formatMoney(preview.totalCost)})
+          </button>
+        </div>
+      </div>
+    </div>
+  );
+}
+
+function RetrofitCampusModal({ campus, era, research, onConfirm, onClose }: {
+  campus: Campus;
+  era: Era;
+  research: string[];
+  onConfirm: (skuId: RackSkuId, maxConcurrent: number) => void;
+  onClose: () => void;
+}) {
+  const [selectedSku, setSelectedSku] = useState<RackSkuId | null>(null);
+  const [concurrencyMode, setConcurrencyMode] = useState<'1' | '10' | '25' | 'custom'>('10');
+  const [customCount, setCustomCount] = useState(1);
+
+  const currentSkuIds = [...new Set(campus.dataCenters.filter(dc => dc.rackSkuId).map(dc => dc.rackSkuId!))];
+
+  const targetSkus = Object.values(RACK_SKU_CONFIGS).filter(s => {
+    if (ERA_ORDER.indexOf(era) < ERA_ORDER.indexOf(s.era)) return false;
+    if (s.requiredResearch && !research.includes(s.requiredResearch)) return false;
+    return true;
+  });
+
+  const eligible = useMemo(() => {
+    if (!selectedSku) return { count: 0, skipped: 0 };
+    let count = 0;
+    let skipped = 0;
+    for (const dc of campus.dataCenters) {
+      if (dc.status !== 'operational' || !dc.rackSkuId || dc.rackSkuId === selectedSku) {
+        skipped++;
+        continue;
+      }
+      const pipelineCount = dc.deploymentCohorts.filter(c => c.stage !== 'decommission').reduce((sum, c) => sum + c.count, 0);
+      if (dc.computeRacksOnline + pipelineCount <= 0) { skipped++; continue; }
+      count++;
+    }
+    return { count, skipped };
+  }, [selectedSku, campus.dataCenters]);
+
+  const maxConcurrent = useMemo(() => {
+    if (eligible.count === 0) return 1;
+    switch (concurrencyMode) {
+      case '1': return 1;
+      case '10': return Math.max(1, Math.ceil(eligible.count * 0.1));
+      case '25': return Math.max(1, Math.ceil(eligible.count * 0.25));
+      case 'custom': return Math.max(1, Math.min(customCount, eligible.count));
+    }
+  }, [concurrencyMode, customCount, eligible.count]);
+
+  const capacityMaintained = eligible.count > 0 ? Math.round(((eligible.count - maxConcurrent) / eligible.count) * 100) : 100;
+
+  const estimatedBatches = eligible.count > 0 ? Math.ceil(eligible.count / maxConcurrent) : 0;
+
+  return (
+    <div className="fixed inset-0 bg-black/60 flex items-center justify-center z-50" onClick={onClose}>
+      <div className="bg-surface-900 border border-surface-700 rounded-xl p-6 max-w-lg w-full mx-4 shadow-2xl max-h-[80vh] flex flex-col" onClick={e => e.stopPropagation()}>
+        <h3 className="text-lg font-bold mb-4 flex items-center gap-2"><RefreshCw size={18} className="text-violet-400" /> Retrofit Campus</h3>
+
+        <div className="space-y-4 overflow-y-auto flex-1 min-h-0">
+          <div>
+            <label className="text-xs text-surface-400 mb-2 block">Target SKU</label>
+            <div className="space-y-1.5">
+              {targetSkus.map(s => {
+                const isCurrentOnly = currentSkuIds.length === 1 && currentSkuIds[0] === s.id;
+                return (
+                  <button key={s.id}
+                    onClick={() => !isCurrentOnly && setSelectedSku(s.id)}
+                    disabled={isCurrentOnly}
+                    className={`w-full flex items-center justify-between p-3 rounded-lg border text-left text-sm transition-colors ${
+                      selectedSku === s.id ? 'border-violet-500 bg-violet-500/10' :
+                      isCurrentOnly ? 'border-surface-700 opacity-40 cursor-not-allowed' :
+                      'border-surface-600 hover:border-surface-500 cursor-pointer'
+                    }`}>
+                    <div>
+                      <div className="font-medium">{s.name}</div>
+                      <div className="text-xs text-surface-400">{s.flopsPerRack} FLOPS | {s.powerDrawKW} kW | {formatMoney(s.baseCost)}/rack</div>
+                    </div>
+                    {isCurrentOnly && <span className="text-xs text-surface-500">Current</span>}
+                    {selectedSku === s.id && <CheckCircle size={16} className="text-violet-400" />}
+                  </button>
+                );
+              })}
+            </div>
+          </div>
+
+          {selectedSku && eligible.count > 0 && (
+            <>
+              <div>
+                <label className="text-xs text-surface-400 mb-2 block">Concurrency</label>
+                <div className="flex gap-1.5">
+                  {([
+                    { key: '1' as const, label: '1 at a time' },
+                    { key: '10' as const, label: `10% = ${Math.max(1, Math.ceil(eligible.count * 0.1))}` },
+                    { key: '25' as const, label: `25% = ${Math.max(1, Math.ceil(eligible.count * 0.25))}` },
+                    { key: 'custom' as const, label: 'Custom' },
+                  ]).map(opt => (
+                    <button key={opt.key} onClick={() => setConcurrencyMode(opt.key)}
+                      className={`flex-1 py-2 text-xs rounded-lg border transition-colors ${
+                        concurrencyMode === opt.key ? 'border-violet-500 bg-violet-500/10 text-violet-300' : 'border-surface-600 text-surface-400 hover:border-surface-500'
+                      }`}>
+                      {opt.label}
+                    </button>
+                  ))}
+                </div>
+                {concurrencyMode === 'custom' && (
+                  <input type="number" min={1} max={eligible.count} value={customCount}
+                    onChange={e => setCustomCount(Math.max(1, parseInt(e.target.value) || 1))}
+                    className="mt-2 w-full bg-surface-800 border border-surface-600 rounded-lg px-3 py-2 text-sm" />
+                )}
+              </div>
+
+              <div className="bg-surface-800 rounded-lg p-3 text-sm space-y-1.5">
+                <div className="flex justify-between"><span className="text-surface-400">DCs to retrofit:</span><span>{eligible.count} of {campus.dataCenters.length}</span></div>
+                <div className="flex justify-between"><span className="text-surface-400">Concurrent retrofits:</span><span>{maxConcurrent}</span></div>
+                <div className="flex justify-between"><span className="text-surface-400">Estimated batches:</span><span>{estimatedBatches}</span></div>
+                <div className="flex justify-between">
+                  <span className="text-surface-400">Capacity maintained:</span>
+                  <span className={capacityMaintained >= 75 ? 'text-green-400' : capacityMaintained >= 50 ? 'text-amber-400' : 'text-red-400'}>~{capacityMaintained}%</span>
+                </div>
+                {eligible.skipped > 0 && (
+                  <div className="text-xs text-surface-500 mt-1">{eligible.skipped} DCs skipped (constructing, empty, or already target SKU)</div>
+                )}
+              </div>
+            </>
+          )}
+        </div>
+
+        <div className="flex gap-3 mt-4">
+          <button onClick={onClose} className="flex-1 bg-surface-700 hover:bg-surface-600 rounded-lg py-2 text-sm">Cancel</button>
+          <button
+            onClick={() => selectedSku && onConfirm(selectedSku, maxConcurrent)}
+            disabled={!selectedSku || eligible.count === 0}
+            className="flex-1 bg-violet-600 hover:bg-violet-700 disabled:opacity-50 disabled:cursor-not-allowed text-white rounded-lg py-2 text-sm font-medium">
+            Start Campus Retrofit
+          </button>
+        </div>
+      </div>
+    </div>
+  );
+}
+
+function CampusRetrofitProgress({ campus, onCancel }: { campus: Campus; onCancel: () => void }) {
+  const queue = campus.retrofitQueue;
+  if (!queue) return null;
+
+  const total = queue.pendingDCIds.length + queue.activeDCIds.length + queue.completedDCIds.length;
+  const completed = queue.completedDCIds.length;
+  const active = queue.activeDCIds.length;
+  const pending = queue.pendingDCIds.length;
+  const pct = total > 0 ? (completed / total) * 100 : 0;
+
+  return (
+    <div className="bg-violet-500/10 border border-violet-500/30 rounded-xl p-4 space-y-3">
+      <div className="flex items-center justify-between">
+        <div className="flex items-center gap-2">
+          <RefreshCw size={16} className="text-violet-400 animate-spin" style={{ animationDuration: '3s' }} />
+          <span className="text-sm font-medium">Campus Retrofit — {RACK_SKU_CONFIGS[queue.targetSkuId].name}</span>
+        </div>
+        <button onClick={onCancel} className="flex items-center gap-1 text-xs text-surface-400 hover:text-red-400 transition-colors">
+          <X size={12} /> Cancel
+        </button>
+      </div>
+      <div className="h-2 bg-surface-700 rounded-full overflow-hidden">
+        <div className="h-full bg-violet-500 rounded-full transition-all" style={{ width: `${pct}%` }} />
+      </div>
+      <div className="flex justify-between text-xs text-surface-400">
+        <span>{completed} of {total} complete</span>
+        <span>{active} active | {pending} pending</span>
+      </div>
+    </div>
+  );
+}
+
+// ─── Campus Detail View ────────────────────────────────────────���
 
 function CampusDetailView({ clusterId, campusId }: { clusterId: string; campusId: string }) {
   const cluster = useGameStore((s) => s.infrastructure.clusters.find(c => c.id === clusterId));
@@ -495,15 +909,34 @@ function CampusDetailView({ clusterId, campusId }: { clusterId: string; campusId
   const setNav = useGameStore((s) => s.setInfraNav);
   const buildDC = useGameStore((s) => s.buildDataCenter);
   const addDCs = useGameStore((s) => s.addDCsToCampus);
+  const fillCampus = useGameStore((s) => s.fillCampusToCapacity);
+  const startRetrofit = useGameStore((s) => s.startCampusRetrofit);
+  const cancelRetrofit = useGameStore((s) => s.cancelCampusRetrofit);
   const money = useGameStore((s) => s.economy.money);
+  const era = useGameStore((s) => s.meta.currentEra);
+  const research = useGameStore((s) => s.research.completedResearch);
 
   const [showAddDC, setShowAddDC] = useState(false);
   const [dcName, setDcName] = useState('');
   const [bulkCount, setBulkCount] = useState(1);
+  const [showFillAll, setShowFillAll] = useState(false);
+  const [showRetrofit, setShowRetrofit] = useState(false);
 
   if (!campus || !cluster) return <div className="text-surface-400">Campus not found.</div>;
 
   const tierConfig = DC_TIER_CONFIGS[campus.dcTier];
+  const operationalDCs = campus.dataCenters.filter(dc => dc.status === 'operational');
+  const hasRetrofitQueue = !!campus.retrofitQueue;
+
+  const fillableDCs = operationalDCs.filter(dc => {
+    const maxCompute = maxComputeRacks(tierConfig.rackSlots);
+    const pipelineCount = dc.deploymentCohorts.filter(c => c.stage !== 'decommission').reduce((sum, c) => sum + c.count, 0);
+    return maxCompute - (dc.computeRacksOnline + pipelineCount) > 0;
+  });
+
+  const retrofitEligibleDCs = operationalDCs.filter(dc =>
+    dc.rackSkuId && (dc.computeRacksOnline + dc.deploymentCohorts.filter(c => c.stage !== 'decommission').reduce((sum, c) => sum + c.count, 0)) > 0,
+  );
 
   return (
     <div className="space-y-6">
@@ -516,6 +949,20 @@ function CampusDetailView({ clusterId, campusId }: { clusterId: string; campusId
           </div>
         </div>
         <div className="flex gap-2">
+          {operationalDCs.length > 0 && !hasRetrofitQueue && (
+            <>
+              <button onClick={() => setShowFillAll(true)}
+                disabled={fillableDCs.length === 0}
+                className="flex items-center gap-1.5 bg-surface-700 hover:bg-surface-600 disabled:opacity-50 disabled:cursor-not-allowed text-white rounded-lg px-3 py-2 text-sm">
+                <Rocket size={14} /> Fill All DCs
+              </button>
+              <button onClick={() => setShowRetrofit(true)}
+                disabled={retrofitEligibleDCs.length === 0}
+                className="flex items-center gap-1.5 bg-violet-600 hover:bg-violet-700 disabled:opacity-50 disabled:cursor-not-allowed text-white rounded-lg px-3 py-2 text-sm">
+                <RefreshCw size={14} /> Retrofit Campus
+              </button>
+            </>
+          )}
           <button onClick={() => setShowAddDC(true)}
             className="flex items-center gap-1.5 bg-accent hover:bg-accent-dark text-white rounded-lg px-4 py-2 text-sm font-medium">
             <Plus size={16} /> Add DC
@@ -523,6 +970,11 @@ function CampusDetailView({ clusterId, campusId }: { clusterId: string; campusId
         </div>
       </div>
 
+      {/* Campus Retrofit Progress Banner */}
+      {campus.retrofitQueue && (
+        <CampusRetrofitProgress campus={campus} onCancel={() => cancelRetrofit(campusId)} />
+      )}
+
       {campus.dataCenters.length === 0 && (
         <TutorialHint id="first-dc">
           Add a data center to this campus. Once built, you can deploy racks to start generating compute.
@@ -530,46 +982,56 @@ function CampusDetailView({ clusterId, campusId }: { clusterId: string; campusId
       )}
 
       <div className="grid grid-cols-1 lg:grid-cols-2 gap-4">
-        {campus.dataCenters.map(dc => (
+        {campus.dataCenters.map(dc => {
-          <button key={dc.id}
+          const queueStatus = campus.retrofitQueue
-            onClick={() => (dc.status === 'operational' || dc.status === 'retrofitting') && setNav({
+            ? campus.retrofitQueue.pendingDCIds.includes(dc.id) ? 'queued'
-              level: 'datacenter', clusterId, campusId, datacenterId: dc.id,
+            : campus.retrofitQueue.completedDCIds.includes(dc.id) ? 'retrofit-done'
-            })}
+            : null
-            className="bg-surface-800 border border-surface-700 rounded-xl p-4 text-left hover:border-accent/50 transition-colors">
+            : null;
-            <div className="flex items-center justify-between mb-3">
-              <div className="flex items-center gap-2">
-                <Server size={16} className="text-violet-400" />
-                <span className="font-bold">{dc.name}</span>
-                {dc.rackSkuId && <span className="text-xs bg-surface-700 text-surface-300 px-2 py-0.5 rounded">{RACK_SKU_CONFIGS[dc.rackSkuId].name}</span>}
-                {dc.status === 'constructing' && <span className="text-xs bg-amber-500/20 text-amber-400 px-2 py-0.5 rounded">Building</span>}
-                {dc.status === 'retrofitting' && <span className="text-xs bg-violet-500/20 text-violet-400 px-2 py-0.5 rounded">Retrofitting</span>}
-              </div>
-              <ChevronRight size={14} className="text-surface-500" />
-            </div>
 
-            {dc.status === 'constructing' ? (
+          return (
-              <div>
+            <button key={dc.id}
-                <div className="flex justify-between text-xs mb-1">
+              onClick={() => (dc.status === 'operational' || dc.status === 'retrofitting') && setNav({
-                  <span className="text-surface-400">Construction</span>
+                level: 'datacenter', clusterId, campusId, datacenterId: dc.id,
-                  <span className="font-mono">{Math.floor((dc.constructionProgress / dc.constructionTotal) * 100)}%</span>
+              })}
-                </div>
+              className="bg-surface-800 border border-surface-700 rounded-xl p-4 text-left hover:border-accent/50 transition-colors">
-                <div className="h-2 bg-surface-700 rounded-full overflow-hidden">
+              <div className="flex items-center justify-between mb-3">
-                  <div className="h-full bg-amber-500 rounded-full transition-all" style={{ width: `${(dc.constructionProgress / dc.constructionTotal) * 100}%` }} />
+                <div className="flex items-center gap-2">
+                  <Server size={16} className="text-violet-400" />
+                  <span className="font-bold">{dc.name}</span>
+                  {dc.rackSkuId && <span className="text-xs bg-surface-700 text-surface-300 px-2 py-0.5 rounded">{RACK_SKU_CONFIGS[dc.rackSkuId].name}</span>}
+                  {dc.status === 'constructing' && <span className="text-xs bg-amber-500/20 text-amber-400 px-2 py-0.5 rounded">Building</span>}
+                  {dc.status === 'retrofitting' && <span className="text-xs bg-violet-500/20 text-violet-400 px-2 py-0.5 rounded">Retrofitting</span>}
+                  {queueStatus === 'queued' && <span className="text-xs bg-surface-600 text-surface-300 px-2 py-0.5 rounded">Queued</span>}
+                  {queueStatus === 'retrofit-done' && <span className="text-xs bg-green-500/20 text-green-400 px-2 py-0.5 rounded flex items-center gap-1"><CheckCircle size={10} /> Done</span>}
                 </div>
+                <ChevronRight size={14} className="text-surface-500" />
               </div>
-            ) : (
+
-              <div className="space-y-2">
+              {dc.status === 'constructing' ? (
-                <DeploymentProgressBar dc={dc} />
+                <div>
-                <NetworkHealthIndicator dc={dc} />
+                  <div className="flex justify-between text-xs mb-1">
-                {dc.deploymentCohorts.length > 0 && <CohortStageBreakdown cohorts={dc.deploymentCohorts} />}
+                    <span className="text-surface-400">Construction</span>
-                <div className="flex justify-between text-xs text-surface-400">
+                    <span className="font-mono">{Math.floor((dc.constructionProgress / dc.constructionTotal) * 100)}%</span>
-                  <span>Uptime: {formatPercent(dc.currentUptime)}</span>
+                  </div>
-                  <span>Cost: {formatMoney(dc.energyCostPerTick + dc.maintenanceCostPerTick)}/s</span>
+                  <div className="h-2 bg-surface-700 rounded-full overflow-hidden">
+                    <div className="h-full bg-amber-500 rounded-full transition-all" style={{ width: `${(dc.constructionProgress / dc.constructionTotal) * 100}%` }} />
+                  </div>
                 </div>
-              </div>
+              ) : (
-            )}
+                <div className="space-y-2">
-          </button>
+                  <DeploymentProgressBar dc={dc} />
-        ))}
+                  <NetworkHealthIndicator dc={dc} />
+                  {dc.deploymentCohorts.length > 0 && <CohortStageBreakdown cohorts={dc.deploymentCohorts} />}
+                  <div className="flex justify-between text-xs text-surface-400">
+                    <span>Uptime: {formatPercent(dc.currentUptime)}</span>
+                    <span>Cost: {formatMoney(dc.energyCostPerTick + dc.maintenanceCostPerTick)}/s</span>
+                  </div>
+                </div>
+              )}
+            </button>
+          );
+        })}
       </div>
 
       {showAddDC && (
@@ -612,6 +1074,27 @@ function CampusDetailView({ clusterId, campusId }: { clusterId: string; campusId
           </div>
         </div>
       )}
+
+      {showFillAll && (
+        <FillAllDCsModal
+          campus={campus}
+          money={money}
+          era={era}
+          research={research}
+          onConfirm={(skuId) => { fillCampus(campusId, skuId); setShowFillAll(false); }}
+          onClose={() => setShowFillAll(false)}
+        />
+      )}
+
+      {showRetrofit && (
+        <RetrofitCampusModal
+          campus={campus}
+          era={era}
+          research={research}
+          onConfirm={(skuId, maxConcurrent) => { startRetrofit(campusId, skuId, maxConcurrent); setShowRetrofit(false); }}
+          onClose={() => setShowRetrofit(false)}
+        />
+      )}
     </div>
   );
 }

apps/web/src/store/index.ts

@@ -9,7 +9,7 @@ import type {
   Cluster, Campus, DataCenter, DCTier, RackSkuId, TrainingJob,
   ActiveResearch, OwnedDataset, LocationId,
   DeploymentCohort, PipelineStage,
-  NetworkHealthState,
+  NetworkHealthState, CampusRetrofitQueue,
 } from '@ai-tycoon/shared';
 import type { FundingRoundType, OverloadPolicy, TuningPreset, ModelTuning } from '@ai-tycoon/shared';
 import {
@@ -79,6 +79,10 @@ interface Actions {
   addDCsToCampus: (campusId: string, count: number) => void;
   retrofitDC: (dataCenterId: string, newSkuId: RackSkuId) => void;
   cancelRetrofit: (dataCenterId: string) => void;
+  fillCampusToCapacity: (campusId: string, skuId: RackSkuId) => void;
+  fillClusterToCapacity: (clusterId: string, skuId: RackSkuId) => void;
+  startCampusRetrofit: (campusId: string, targetSkuId: RackSkuId, maxConcurrent: number) => void;
+  cancelCampusRetrofit: (campusId: string) => void;
   upgradeDataCenter: (dataCenterId: string, upgrade: 'cooling' | 'redundancy') => void;
   startTraining: (job: Omit<TrainingJob, 'progressTicks'>) => void;
   deployModel: (modelId: string) => void;
@@ -166,6 +170,62 @@ function updateDCInInfra(infra: InfrastructureState, dcId: string, updater: (dc:
   };
 }
 
+function updateClusterInInfra(infra: InfrastructureState, clusterId: string, updater: (cluster: Cluster) => Cluster): InfrastructureState {
+  return {
+    ...infra,
+    clusters: infra.clusters.map(cluster =>
+      cluster.id === clusterId ? updater(cluster) : cluster,
+    ),
+  };
+}
+
+export function computeFillForDC(
+  dc: DataCenter,
+  skuId: RackSkuId,
+  availableMoney: number,
+): { qty: number; cost: number } {
+  if (dc.status !== 'operational') return { qty: 0, cost: 0 };
+  if (dc.rackSkuId !== null && dc.rackSkuId !== skuId) return { qty: 0, cost: 0 };
+
+  const sku = RACK_SKU_CONFIGS[skuId];
+  const tierConfig = DC_TIER_CONFIGS[dc.tier];
+  const maxCompute = maxComputeRacks(tierConfig.rackSlots);
+  const pipelineCount = dc.deploymentCohorts.filter(c => c.stage !== 'decommission').reduce((sum, c) => sum + c.count, 0);
+  const existingCompute = dc.computeRacksOnline + pipelineCount;
+  const available = maxCompute - existingCompute;
+  if (available <= 0) return { qty: 0, cost: 0 };
+
+  const affordableQty = Math.floor(availableMoney / sku.baseCost);
+  const powerLimit = Math.floor((tierConfig.powerBudgetKW - dc.computeRacksOnline * sku.powerDrawKW) / sku.powerDrawKW);
+  const qty = Math.min(available, affordableQty, Math.max(0, powerLimit));
+  if (qty <= 0) return { qty: 0, cost: 0 };
+
+  return { qty, cost: sku.baseCost * qty };
+}
+
+function startRetrofitOnDC(dc: DataCenter, targetSkuId: RackSkuId): DataCenter {
+  const pipelineCount = dc.deploymentCohorts.filter(c => c.stage !== 'decommission').reduce((sum, c) => sum + c.count, 0);
+  const totalRacks = dc.computeRacksOnline + pipelineCount;
+  if (totalRacks <= 0) return dc;
+
+  const oldSku = RACK_SKU_CONFIGS[dc.rackSkuId!];
+  const decommTicks = Math.ceil(oldSku.pipelineTimeTicks.installation * (1 + COHORT_SCALE_FACTOR * totalRacks));
+
+  return {
+    ...dc,
+    status: 'retrofitting' as const,
+    deploymentCohorts: [],
+    retrofitState: {
+      fromSkuId: dc.rackSkuId!,
+      toSkuId: targetSkuId,
+      phase: 'decommissioning' as const,
+      progress: 0,
+      total: decommTicks,
+      racksRemaining: totalRacks,
+    },
+  };
+}
+
 function updateCampusInInfra(infra: InfrastructureState, campusId: string, updater: (campus: Campus) => Campus): InfrastructureState {
   return {
     ...infra,
@@ -297,6 +357,7 @@ export const useGameStore = create<Store>()(
           status: 'constructing',
           constructionProgress: 0,
           constructionTotal: buildTime,
+          retrofitQueue: null,
         };
 
         return {
@@ -535,6 +596,179 @@ export const useGameStore = create<Store>()(
         };
       }),
 
+      // --- Infrastructure: Bulk Actions ---
+
+      fillCampusToCapacity: (campusId, skuId) => set((s) => {
+        const found = findCampus(s.infrastructure, campusId);
+        if (!found || found.campus.status !== 'operational') return s;
+
+        const sku = RACK_SKU_CONFIGS[skuId];
+        const eraOrder: Era[] = ['startup', 'scaleup', 'bigtech', 'agi'];
+        if (eraOrder.indexOf(s.meta.currentEra) < eraOrder.indexOf(sku.era)) return s;
+        if (sku.requiredResearch && !s.research.completedResearch.includes(sku.requiredResearch)) return s;
+
+        let remainingMoney = s.economy.money;
+        const dcUpdates = new Map<string, DeploymentCohort>();
+
+        for (const dc of found.campus.dataCenters) {
+          const { qty, cost } = computeFillForDC(dc, skuId, remainingMoney);
+          if (qty <= 0) continue;
+
+          const baseTicks = PIPELINE_ORDER_BASE_TICKS;
+          const scaledTicks = Math.ceil(baseTicks * (1 + COHORT_SCALE_FACTOR * qty));
+          dcUpdates.set(dc.id, {
+            id: uuid(),
+            count: qty,
+            skuId,
+            stage: 'ordered' as PipelineStage,
+            stageProgress: 0,
+            stageTotal: scaledTicks,
+            repairCount: 0,
+          });
+          remainingMoney -= cost;
+        }
+
+        if (dcUpdates.size === 0) return s;
+
+        return {
+          economy: { ...s.economy, money: remainingMoney },
+          infrastructure: updateCampusInInfra(s.infrastructure, campusId, (campus) => ({
+            ...campus,
+            dataCenters: campus.dataCenters.map(dc => {
+              const cohort = dcUpdates.get(dc.id);
+              if (!cohort) return dc;
+              return { ...dc, rackSkuId: skuId, deploymentCohorts: [...dc.deploymentCohorts, cohort] };
+            }),
+          })),
+        };
+      }),
+
+      fillClusterToCapacity: (clusterId, skuId) => set((s) => {
+        const cluster = findCluster(s.infrastructure, clusterId);
+        if (!cluster || cluster.status !== 'operational') return s;
+
+        const sku = RACK_SKU_CONFIGS[skuId];
+        const eraOrder: Era[] = ['startup', 'scaleup', 'bigtech', 'agi'];
+        if (eraOrder.indexOf(s.meta.currentEra) < eraOrder.indexOf(sku.era)) return s;
+        if (sku.requiredResearch && !s.research.completedResearch.includes(sku.requiredResearch)) return s;
+
+        let remainingMoney = s.economy.money;
+        const allDcUpdates = new Map<string, DeploymentCohort>();
+
+        for (const campus of cluster.campuses) {
+          if (campus.status !== 'operational') continue;
+          for (const dc of campus.dataCenters) {
+            const { qty, cost } = computeFillForDC(dc, skuId, remainingMoney);
+            if (qty <= 0) continue;
+
+            const baseTicks = PIPELINE_ORDER_BASE_TICKS;
+            const scaledTicks = Math.ceil(baseTicks * (1 + COHORT_SCALE_FACTOR * qty));
+            allDcUpdates.set(dc.id, {
+              id: uuid(),
+              count: qty,
+              skuId,
+              stage: 'ordered' as PipelineStage,
+              stageProgress: 0,
+              stageTotal: scaledTicks,
+              repairCount: 0,
+            });
+            remainingMoney -= cost;
+          }
+        }
+
+        if (allDcUpdates.size === 0) return s;
+
+        return {
+          economy: { ...s.economy, money: remainingMoney },
+          infrastructure: updateClusterInInfra(s.infrastructure, clusterId, (cl) => ({
+            ...cl,
+            campuses: cl.campuses.map(campus => ({
+              ...campus,
+              dataCenters: campus.dataCenters.map(dc => {
+                const cohort = allDcUpdates.get(dc.id);
+                if (!cohort) return dc;
+                return { ...dc, rackSkuId: skuId, deploymentCohorts: [...dc.deploymentCohorts, cohort] };
+              }),
+            })),
+          })),
+        };
+      }),
+
+      startCampusRetrofit: (campusId, targetSkuId, maxConcurrent) => set((s) => {
+        const found = findCampus(s.infrastructure, campusId);
+        if (!found || found.campus.status !== 'operational') return s;
+        if (found.campus.retrofitQueue) return s;
+
+        const sku = RACK_SKU_CONFIGS[targetSkuId];
+        const eraOrder: Era[] = ['startup', 'scaleup', 'bigtech', 'agi'];
+        if (eraOrder.indexOf(s.meta.currentEra) < eraOrder.indexOf(sku.era)) return s;
+        if (sku.requiredResearch && !s.research.completedResearch.includes(sku.requiredResearch)) return s;
+
+        const eligible: string[] = [];
+        const skipped: string[] = [];
+
+        for (const dc of found.campus.dataCenters) {
+          if (dc.status !== 'operational' || !dc.rackSkuId || dc.rackSkuId === targetSkuId) {
+            skipped.push(dc.id);
+            continue;
+          }
+          const pipelineCount = dc.deploymentCohorts.filter(c => c.stage !== 'decommission').reduce((sum, c) => sum + c.count, 0);
+          if (dc.computeRacksOnline + pipelineCount <= 0) {
+            skipped.push(dc.id);
+            continue;
+          }
+          eligible.push(dc.id);
+        }
+
+        if (eligible.length === 0) return s;
+
+        const concurrent = Math.max(1, Math.min(maxConcurrent, eligible.length));
+        const toStartNow = eligible.slice(0, concurrent);
+        const pending = eligible.slice(concurrent);
+
+        const queue: CampusRetrofitQueue = {
+          targetSkuId,
+          maxConcurrent: concurrent,
+          pendingDCIds: pending,
+          activeDCIds: toStartNow,
+          completedDCIds: [],
+          skippedDCIds: skipped,
+        };
+
+        return {
+          infrastructure: updateCampusInInfra(s.infrastructure, campusId, (campus) => ({
+            ...campus,
+            retrofitQueue: queue,
+            dataCenters: campus.dataCenters.map(dc => {
+              if (!toStartNow.includes(dc.id)) return dc;
+              return startRetrofitOnDC(dc, targetSkuId);
+            }),
+          })),
+        };
+      }),
+
+      cancelCampusRetrofit: (campusId) => set((s) => {
+        const found = findCampus(s.infrastructure, campusId);
+        if (!found || !found.campus.retrofitQueue) return s;
+
+        const queue = found.campus.retrofitQueue;
+        if (queue.activeDCIds.length === 0) {
+          return {
+            infrastructure: updateCampusInInfra(s.infrastructure, campusId, (campus) => ({
+              ...campus,
+              retrofitQueue: null,
+            })),
+          };
+        }
+
+        return {
+          infrastructure: updateCampusInInfra(s.infrastructure, campusId, (campus) => ({
+            ...campus,
+            retrofitQueue: { ...queue, pendingDCIds: [] },
+          })),
+        };
+      }),
+
       // --- Infrastructure: Upgrades ---
 
       upgradeDataCenter: (dataCenterId, upgrade) => set((s) => {

packages/game-engine/src/systems/infrastructureSystem.ts

@@ -1,6 +1,7 @@
 import type {
   GameState, InfrastructureState, Cluster, Campus, DataCenter,
-  DeploymentCohort, NetworkHealthState, PipelineStage,
+  DeploymentCohort, NetworkHealthState, PipelineStage, RackSkuId,
+  CampusRetrofitQueue,
 } from '@ai-tycoon/shared';
 import {
   LOCATION_CONFIGS,
@@ -442,7 +443,74 @@ export function processInfrastructure(state: GameState): InfraTickResult {
         };
       });
 
-      return { ...campus, dataCenters };
+      // Process campus retrofit queue
+      let finalDCs = dataCenters;
+      let updatedQueue: CampusRetrofitQueue | null = campus.retrofitQueue ?? null;
+
+      if (updatedQueue && updatedQueue.pendingDCIds.length + updatedQueue.activeDCIds.length > 0) {
+        updatedQueue = { ...updatedQueue };
+
+        // Detect DCs that just completed retrofit (were active, now operational)
+        const newlyCompleted = finalDCs.filter(
+          dc => updatedQueue!.activeDCIds.includes(dc.id) && dc.status === 'operational',
+        );
+
+        if (newlyCompleted.length > 0) {
+          updatedQueue.activeDCIds = updatedQueue.activeDCIds.filter(
+            id => !newlyCompleted.some(dc => dc.id === id),
+          );
+          updatedQueue.completedDCIds = [
+            ...updatedQueue.completedDCIds,
+            ...newlyCompleted.map(dc => dc.id),
+          ];
+        }
+
+        // Promote DCs from pending to active
+        const slotsAvailable = updatedQueue.maxConcurrent - updatedQueue.activeDCIds.length;
+        if (slotsAvailable > 0 && updatedQueue.pendingDCIds.length > 0) {
+          const toStart = updatedQueue.pendingDCIds.slice(0, slotsAvailable);
+          updatedQueue.pendingDCIds = updatedQueue.pendingDCIds.slice(toStart.length);
+          updatedQueue.activeDCIds = [...updatedQueue.activeDCIds, ...toStart];
+
+          finalDCs = finalDCs.map(dc => {
+            if (!toStart.includes(dc.id)) return dc;
+            if (dc.status !== 'operational' || !dc.rackSkuId) return dc;
+
+            const pipelineCount = dc.deploymentCohorts.filter(c => c.stage !== 'decommission').reduce((sum, c) => sum + c.count, 0);
+            const totalRacks = dc.computeRacksOnline + pipelineCount;
+            if (totalRacks <= 0) return dc;
+
+            const oldSku = RACK_SKU_CONFIGS[dc.rackSkuId as RackSkuId];
+            const decommTicks = Math.ceil(oldSku.pipelineTimeTicks.installation * (1 + COHORT_SCALE_FACTOR * totalRacks));
+
+            return {
+              ...dc,
+              status: 'retrofitting' as const,
+              deploymentCohorts: [],
+              retrofitState: {
+                fromSkuId: dc.rackSkuId as RackSkuId,
+                toSkuId: updatedQueue!.targetSkuId,
+                phase: 'decommissioning' as const,
+                progress: 0,
+                total: decommTicks,
+                racksRemaining: totalRacks,
+              },
+            };
+          });
+        }
+
+        // Check if queue is complete
+        if (updatedQueue.pendingDCIds.length === 0 && updatedQueue.activeDCIds.length === 0) {
+          notifications.push({
+            title: 'Campus Retrofit Complete',
+            message: `All DCs in ${campus.name} have been retrofitted to ${RACK_SKU_CONFIGS[updatedQueue.targetSkuId].name}!`,
+            type: 'success',
+          });
+          updatedQueue = null;
+        }
+      }
+
+      return { ...campus, dataCenters: finalDCs, retrofitQueue: updatedQueue };
     });
 
     return { ...cluster, campuses };

packages/shared/src/types/infrastructure.ts

@@ -18,6 +18,15 @@ export interface Cluster {
 
 export type CampusStatus = 'constructing' | 'operational';
 
+export interface CampusRetrofitQueue {
+  targetSkuId: RackSkuId;
+  maxConcurrent: number;
+  pendingDCIds: string[];
+  activeDCIds: string[];
+  completedDCIds: string[];
+  skippedDCIds: string[];
+}
+
 export interface Campus {
   id: string;
   name: string;
@@ -27,6 +36,7 @@ export interface Campus {
   status: CampusStatus;
   constructionProgress: number;
   constructionTotal: number;
+  retrofitQueue: CampusRetrofitQueue | null;
 }
 
 // --- Data Center ---