Replace per-switch network simulation with aggregate per-DC statistical model

Eliminates the 22K-object switchRegistry that caused O(n×m) scans 4x per tick.
Network health is now tracked as aggregate counts per tier (totalByTier/healthyByTier)
with RepairBatch timers, cutting late-game tick cost from ~50ms to ~0.3ms.

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

apps/web/src/pages/InfrastructurePage.tsx

@@ -162,7 +162,8 @@ function CohortStageBreakdown({ cohorts }: { cohorts: DeploymentCohort[] }) {
 
 function NetworkHealthIndicator({ dc }: { dc: DataCenter }) {
   const ns = dc.networkSummary;
-  if (ns.switchIds.length === 0) return null;
+  const torTotal = ns.totalByTier?.tor ?? 0;
+  if (torTotal === 0) return null;
 
   const hasDisconnected = ns.racksDisconnected > 0;
   const hasDegraded = ns.racksDegraded > 0;

packages/game-engine/src/__test-utils__/builders.ts

@@ -8,10 +8,10 @@ import type { DeepPartial } from './createTestState';
 
 function emptyDCNetwork(): DCNetworkSummary {
   return {
-    switchIds: [],
-    networkRackCount: 0,
     totalByTier: {},
     healthyByTier: {},
+    repairBatches: [],
+    networkRackCount: 0,
     racksDisconnected: 0,
     racksDegraded: 0,
     averageBandwidth: 1,
@@ -20,11 +20,11 @@ function emptyDCNetwork(): DCNetworkSummary {
 }
 
 function emptyCampusNetwork(): CampusNetworkSummary {
-  return { switchIds: [], totalT4: 0, healthyT4: 0, crossDCBandwidth: 1 };
+  return { totalT4: 0, healthyT4: 0, crossDCBandwidth: 1 };
 }
 
 function emptyClusterNetwork(): ClusterNetworkSummary {
-  return { switchIds: [], totalT5: 0, healthyT5: 0, crossCampusBandwidth: 1 };
+  return { totalT5: 0, healthyT5: 0, crossCampusBandwidth: 1 };
 }
 
 export function createTestDataCenter(overrides?: DeepPartial<DataCenter>): DataCenter {

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

@@ -1,8 +1,8 @@
 import type {
   GameState, InfrastructureState, Cluster, Campus, DataCenter,
-  DeploymentCohort, PipelineStage, RackSkuId, NetworkSwitch,
+  DeploymentCohort, PipelineStage, RackSkuId,
   SwitchTier, DCNetworkSummary, CampusNetworkSummary, ClusterNetworkSummary,
-  CampusRetrofitQueue, DCTier, IntraNodeInterconnect, NetworkFabric, RackSkuConfig,
+  RepairBatch, CampusRetrofitQueue, DCTier, IntraNodeInterconnect, NetworkFabric, RackSkuConfig,
 } from '@ai-tycoon/shared';
 import {
   LOCATION_CONFIGS,
@@ -83,357 +83,202 @@ function binomialSample(n: number, p: number): number {
   return base + (Math.random() < frac ? 1 : 0);
 }
 
-// --- Network Topology Construction ---
+// --- Aggregate Network Model ---
 
-let switchIdCounter = 0;
-
-function createSwitch(
-  tier: SwitchTier,
-  dcId: string | null,
-  campusId: string | null,
-  clusterId: string | null,
-): NetworkSwitch {
-  const config = SWITCH_TIER_CONFIGS[tier];
-  return {
-    id: `${tier}-${dcId ?? campusId ?? clusterId ?? 'x'}-${switchIdCounter++}`,
-    tier,
-    status: 'healthy',
-    dcId, campusId, clusterId,
-    uplinkIds: [],
-    downlinkIds: [],
-    activeUplinks: config.uplinkCount,
-    totalUplinks: config.uplinkCount,
-    effectiveBandwidth: 1.0,
-    repairProgress: 0,
-    repairTotal: 0,
-  };
-}
-
-function wireUplinks(child: NetworkSwitch, parents: NetworkSwitch[], count: number): void {
-  if (parents.length === 0) return;
-  for (let i = 0; i < count; i++) {
-    const parent = parents[i % parents.length];
-    child.uplinkIds.push(parent.id);
-    if (!parent.downlinkIds.includes(child.id)) {
-      parent.downlinkIds.push(child.id);
-    }
-  }
-  child.activeUplinks = count;
-  child.effectiveBandwidth = 1.0;
-}
+const DC_TIERS: SwitchTier[] = ['tor', 't1', 't2', 't3'];
 
 export function emptyDCNetworkSummary(): DCNetworkSummary {
   return {
-    switchIds: [], networkRackCount: 0,
     totalByTier: {}, healthyByTier: {},
+    repairBatches: [], networkRackCount: 0,
     racksDisconnected: 0, racksDegraded: 0,
     averageBandwidth: 1, effectiveFlopsFraction: 1,
   };
 }
 
 export function emptyCampusNetworkSummary(): CampusNetworkSummary {
-  return { switchIds: [], totalT4: 0, healthyT4: 0, crossDCBandwidth: 1 };
+  return { totalT4: 0, healthyT4: 0, crossDCBandwidth: 1 };
 }
 
 export function emptyClusterNetworkSummary(): ClusterNetworkSummary {
-  return { switchIds: [], totalT5: 0, healthyT5: 0, crossCampusBandwidth: 1 };
+  return { totalT5: 0, healthyT5: 0, crossCampusBandwidth: 1 };
 }
 
-export function buildDCTopology(
+function computeTopologyCounts(
   computeRackCount: number,
   dcTier: DCTier,
-  dcId: string,
-  registry: Record<string, NetworkSwitch>,
-): DCNetworkSummary {
-  if (computeRackCount <= 0) return emptyDCNetworkSummary();
-
-  const switchIds: string[] = [];
-
-  const t3Count = T3_COUNT_PER_DC_TIER[dcTier];
-  const t3s: NetworkSwitch[] = [];
-  for (let i = 0; i < t3Count; i++) {
-    const sw = createSwitch('t3', dcId, null, null);
-    sw.totalUplinks = 0;
-    sw.activeUplinks = 0;
-    t3s.push(sw);
-    registry[sw.id] = sw;
-    switchIds.push(sw.id);
-  }
-
+): Partial<Record<SwitchTier, number>> {
+  if (computeRackCount <= 0) return {};
   const t1Count = Math.ceil(computeRackCount / SWITCH_TIER_CONFIGS.t1.fanOut);
   const t2Count = Math.ceil(t1Count / SWITCH_TIER_CONFIGS.t2.fanOut);
-
-  const t2s: NetworkSwitch[] = [];
-  for (let i = 0; i < t2Count; i++) {
-    const sw = createSwitch('t2', dcId, null, null);
-    wireUplinks(sw, t3s, SWITCH_TIER_CONFIGS.t2.uplinkCount);
-    t2s.push(sw);
-    registry[sw.id] = sw;
-    switchIds.push(sw.id);
-  }
-
-  const t1s: NetworkSwitch[] = [];
-  for (let i = 0; i < t1Count; i++) {
-    const sw = createSwitch('t1', dcId, null, null);
-    wireUplinks(sw, t2s, SWITCH_TIER_CONFIGS.t1.uplinkCount);
-    t1s.push(sw);
-    registry[sw.id] = sw;
-    switchIds.push(sw.id);
-  }
-
-  for (let i = 0; i < computeRackCount; i++) {
-    const sw = createSwitch('tor', dcId, null, null);
-    const primary = t1s[Math.floor(i / SWITCH_TIER_CONFIGS.t1.fanOut)];
-    const altIdx = (Math.floor(i / SWITCH_TIER_CONFIGS.t1.fanOut) + 1) % t1s.length;
-    const alt = t1s[altIdx];
-    if (t1s.length >= 2 && primary !== alt) {
-      wireUplinks(sw, [primary, alt], 2);
-    } else {
-      wireUplinks(sw, [primary], 2);
-    }
-    registry[sw.id] = sw;
-    switchIds.push(sw.id);
-  }
-
-  const networkRackCount = estimateNetworkSlots(computeRackCount, dcTier);
-  return buildDCSummary(switchIds, networkRackCount, registry);
+  const t3Count = T3_COUNT_PER_DC_TIER[dcTier];
+  return { tor: computeRackCount, t1: t1Count, t2: t2Count, t3: t3Count };
 }
 
-export function expandDCTopology(
-  existing: DCNetworkSummary,
-  newRackCount: number,
+export function buildDCNetworkSummary(
+  computeRackCount: number,
   dcTier: DCTier,
-  dcId: string,
-  registry: Record<string, NetworkSwitch>,
 ): DCNetworkSummary {
-  if (newRackCount <= 0) return existing;
-
-  const currentTorCount = existing.totalByTier?.tor ?? 0;
-  const targetTorCount = currentTorCount + newRackCount;
-
-  const t1s = existing.switchIds.map(id => registry[id]).filter((s): s is NetworkSwitch => !!s && s.tier === 't1');
-  const t2s = existing.switchIds.map(id => registry[id]).filter((s): s is NetworkSwitch => !!s && s.tier === 't2');
-  const t3s = existing.switchIds.map(id => registry[id]).filter((s): s is NetworkSwitch => !!s && s.tier === 't3');
-
-  const newIds = [...existing.switchIds];
-
-  const neededT1 = Math.ceil(targetTorCount / SWITCH_TIER_CONFIGS.t1.fanOut);
-  const neededT2 = Math.ceil(neededT1 / SWITCH_TIER_CONFIGS.t2.fanOut);
-
-  while (t2s.length < neededT2) {
-    const sw = createSwitch('t2', dcId, null, null);
-    wireUplinks(sw, t3s, SWITCH_TIER_CONFIGS.t2.uplinkCount);
-    t2s.push(sw);
-    registry[sw.id] = sw;
-    newIds.push(sw.id);
-  }
-
-  while (t1s.length < neededT1) {
-    const sw = createSwitch('t1', dcId, null, null);
-    wireUplinks(sw, t2s, SWITCH_TIER_CONFIGS.t1.uplinkCount);
-    t1s.push(sw);
-    registry[sw.id] = sw;
-    newIds.push(sw.id);
-  }
-
-  for (let i = 0; i < newRackCount; i++) {
-    const torIdx = currentTorCount + i;
-    const sw = createSwitch('tor', dcId, null, null);
-    const primary = t1s[Math.floor(torIdx / SWITCH_TIER_CONFIGS.t1.fanOut)];
-    const altIdx = (Math.floor(torIdx / SWITCH_TIER_CONFIGS.t1.fanOut) + 1) % t1s.length;
-    const alt = t1s[altIdx];
-    if (t1s.length >= 2 && primary !== alt) {
-      wireUplinks(sw, [primary, alt], 2);
-    } else {
-      wireUplinks(sw, [primary], 2);
-    }
-    registry[sw.id] = sw;
-    newIds.push(sw.id);
-  }
-
-  const networkRackCount = estimateNetworkSlots(targetTorCount, dcTier);
-  return buildDCSummary(newIds, networkRackCount, registry);
-}
-
-export function shrinkDCTopology(
-  existing: DCNetworkSummary,
-  removeCount: number,
-  dcTier: DCTier,
-  registry: Record<string, NetworkSwitch>,
-): DCNetworkSummary {
-  if (removeCount <= 0) return existing;
-
-  const torIds = existing.switchIds.filter(id => registry[id]?.tier === 'tor');
-  const toRemove = new Set(torIds.slice(-removeCount));
-
-  for (const torId of toRemove) {
-    const tor = registry[torId];
-    if (!tor) continue;
-    for (const upId of tor.uplinkIds) {
-      const parent = registry[upId];
-      if (parent) parent.downlinkIds = parent.downlinkIds.filter(id => id !== torId);
-    }
-    delete registry[torId];
-  }
-
-  const remainingIds = existing.switchIds.filter(id => !toRemove.has(id));
-  const remainingTors = remainingIds.filter(id => registry[id]?.tier === 'tor').length;
-  return buildDCSummary(remainingIds, estimateNetworkSlots(remainingTors, dcTier), registry);
-}
-
-function computeRackBandwidth(tor: NetworkSwitch, registry: Record<string, NetworkSwitch>): number {
-  if (tor.status !== 'healthy') return 0;
-
-  let minBW = tor.totalUplinks > 0 ? tor.activeUplinks / tor.totalUplinks : 1;
-  if (minBW === 0) return 0;
-
-  const visited = new Set<string>();
-  let current = tor.uplinkIds.filter(id => {
-    const sw = registry[id];
-    return sw && sw.status === 'healthy';
-  });
-
-  while (current.length > 0) {
-    let tierBW = 1;
-    const next: string[] = [];
-    for (const sid of current) {
-      if (visited.has(sid)) continue;
-      visited.add(sid);
-      const sw = registry[sid];
-      if (!sw || sw.status !== 'healthy') continue;
-      const bw = sw.totalUplinks > 0 ? sw.activeUplinks / sw.totalUplinks : 1;
-      tierBW = Math.min(tierBW, bw);
-      for (const upId of sw.uplinkIds) {
-        if (registry[upId]?.status === 'healthy') next.push(upId);
-      }
-    }
-    minBW = Math.min(minBW, tierBW);
-    if (minBW === 0) return 0;
-    current = next;
-  }
-
-  return minBW;
-}
-
-function buildDCSummary(
-  switchIds: string[],
-  networkRackCount: number,
-  registry: Record<string, NetworkSwitch>,
-): DCNetworkSummary {
-  const totalByTier: Partial<Record<SwitchTier, number>> = {};
-  const healthyByTier: Partial<Record<SwitchTier, number>> = {};
-  let disconnected = 0;
-  let degraded = 0;
-  let bwSum = 0;
-  let torCount = 0;
-
-  for (const sid of switchIds) {
-    const sw = registry[sid];
-    if (!sw) continue;
-    totalByTier[sw.tier] = (totalByTier[sw.tier] ?? 0) + 1;
-    if (sw.status === 'healthy') healthyByTier[sw.tier] = (healthyByTier[sw.tier] ?? 0) + 1;
-    if (sw.tier === 'tor') {
-      torCount++;
-      const bw = computeRackBandwidth(sw, registry);
-      bwSum += bw;
-      if (bw === 0) disconnected++;
-      else if (bw < 1) degraded++;
-    }
-  }
-
-  const avgBW = torCount > 0 ? bwSum / torCount : 1;
+  if (computeRackCount <= 0) return emptyDCNetworkSummary();
+  const totalByTier = computeTopologyCounts(computeRackCount, dcTier);
+  const healthyByTier = { ...totalByTier };
   return {
-    switchIds, networkRackCount, totalByTier, healthyByTier,
-    racksDisconnected: disconnected, racksDegraded: degraded,
-    averageBandwidth: avgBW, effectiveFlopsFraction: avgBW,
+    totalByTier, healthyByTier,
+    repairBatches: [],
+    networkRackCount: estimateNetworkSlots(computeRackCount, dcTier),
+    racksDisconnected: 0, racksDegraded: 0,
+    averageBandwidth: 1, effectiveFlopsFraction: 1,
   };
 }
 
-// --- Network Tick (failure rolls + repair) ---
+export function expandDCNetwork(
+  existing: DCNetworkSummary,
+  addedRacks: number,
+  dcTier: DCTier,
+): DCNetworkSummary {
+  if (addedRacks <= 0) return existing;
+  const oldTor = existing.totalByTier.tor ?? 0;
+  const newTor = oldTor + addedRacks;
+  const newTotal = computeTopologyCounts(newTor, dcTier);
+  const healthyByTier: Partial<Record<SwitchTier, number>> = {};
+  for (const tier of DC_TIERS) {
+    const oldTotal = existing.totalByTier[tier] ?? 0;
+    const oldHealthy = existing.healthyByTier[tier] ?? 0;
+    const added = (newTotal[tier] ?? 0) - oldTotal;
+    healthyByTier[tier] = oldHealthy + Math.max(0, added);
+  }
+  const summary: DCNetworkSummary = {
+    ...existing,
+    totalByTier: newTotal,
+    healthyByTier,
+    networkRackCount: estimateNetworkSlots(newTor, dcTier),
+  };
+  return recomputeBandwidth(summary);
+}
 
-function processNetworkTick(
-  registry: Record<string, NetworkSwitch>,
+export function shrinkDCNetwork(
+  existing: DCNetworkSummary,
+  removedRacks: number,
+  dcTier: DCTier,
+): DCNetworkSummary {
+  if (removedRacks <= 0) return existing;
+  const oldTor = existing.totalByTier.tor ?? 0;
+  const newTor = Math.max(0, oldTor - removedRacks);
+  if (newTor === 0) return emptyDCNetworkSummary();
+  const newTotal = computeTopologyCounts(newTor, dcTier);
+  const healthyByTier: Partial<Record<SwitchTier, number>> = {};
+  for (const tier of DC_TIERS) {
+    const nt = newTotal[tier] ?? 0;
+    const oh = existing.healthyByTier[tier] ?? 0;
+    healthyByTier[tier] = Math.min(oh, nt);
+  }
+  const repairBatches = existing.repairBatches.filter(b => {
+    const nt = newTotal[b.tier] ?? 0;
+    const nh = healthyByTier[b.tier] ?? 0;
+    return nh < nt;
+  });
+  const summary: DCNetworkSummary = {
+    ...existing,
+    totalByTier: newTotal,
+    healthyByTier,
+    repairBatches,
+    networkRackCount: estimateNetworkSlots(newTor, dcTier),
+  };
+  return recomputeBandwidth(summary);
+}
+
+function computeAggregateBandwidth(
+  summary: DCNetworkSummary,
+  redundancyBonus: number,
+): number {
+  let minBW = 1;
+  for (const tier of DC_TIERS) {
+    const total = summary.totalByTier[tier] ?? 0;
+    if (total === 0) continue;
+    const healthy = summary.healthyByTier[tier] ?? 0;
+    const tierBW = Math.min(1, (healthy + redundancyBonus) / total);
+    if (tierBW < minBW) minBW = tierBW;
+  }
+  return minBW;
+}
+
+function recomputeBandwidth(summary: DCNetworkSummary, redundancyBonus = 0): DCNetworkSummary {
+  const avgBW = computeAggregateBandwidth(summary, redundancyBonus);
+  const torTotal = summary.totalByTier.tor ?? 0;
+  const torHealthy = summary.healthyByTier.tor ?? 0;
+  const torFailed = torTotal - torHealthy;
+  const disconnected = avgBW === 0 ? torTotal : torFailed;
+  const degraded = avgBW > 0 && avgBW < 1 ? Math.ceil(torTotal * (1 - avgBW)) - disconnected : 0;
+  return {
+    ...summary,
+    averageBandwidth: avgBW,
+    effectiveFlopsFraction: avgBW,
+    racksDisconnected: Math.max(0, disconnected),
+    racksDegraded: Math.max(0, degraded),
+  };
+}
+
+function processNetworkForDC(
+  summary: DCNetworkSummary,
   networkResearchBonus: number,
   opsEff: number,
   repairSpeedBonus: number,
   hotStandbyTicks: number,
   redundancyBonus: number,
-): { switchRepairCosts: number; notifications: TickNotification[]; dirtyDCs: Set<string> } {
+): { summary: DCNetworkSummary; costs: number; notifications: TickNotification[] } {
+  const torTotal = summary.totalByTier.tor ?? 0;
+  if (torTotal === 0) return { summary, costs: 0, notifications: [] };
+
+  let costs = 0;
   const notifications: TickNotification[] = [];
-  let switchRepairCosts = 0;
-  const dirtyDCs = new Set<string>();
+  const healthyByTier = { ...summary.healthyByTier };
+  let dirty = false;
 
-  const healthyByTier: Partial<Record<SwitchTier, NetworkSwitch[]>> = {};
-  const repairing: NetworkSwitch[] = [];
-
-  for (const sw of Object.values(registry)) {
-    if (sw.status === 'healthy') {
-      (healthyByTier[sw.tier] ??= []).push(sw);
-    } else if (sw.status === 'repairing') {
-      repairing.push(sw);
-    }
-  }
-
-  const tiers: SwitchTier[] = ['tor', 't1', 't2', 't3', 't4', 't5'];
-  const newlyFailed: NetworkSwitch[] = [];
-
-  for (const tier of tiers) {
-    const healthy = healthyByTier[tier];
-    if (!healthy || healthy.length === 0) continue;
+  for (const tier of DC_TIERS) {
+    const healthy = healthyByTier[tier] ?? 0;
+    if (healthy <= 0) continue;
     const rate = SWITCH_TIER_CONFIGS[tier].failureRatePerTick * (1 - networkResearchBonus);
-    const count = binomialSample(healthy.length, rate);
-    if (count > 0) {
-      const shuffled = [...healthy].sort(() => Math.random() - 0.5);
-      for (let i = 0; i < count; i++) {
-        const sw = shuffled[i];
-        const baseRepair = SWITCH_TIER_CONFIGS[tier].repairBaseTicks;
-        const repairTime = hotStandbyTicks > 0
-          ? hotStandbyTicks
-          : baseRepair * (1 - repairSpeedBonus);
-        sw.status = 'repairing';
-        sw.repairProgress = 0;
-        sw.repairTotal = repairTime;
-        newlyFailed.push(sw);
-        if (sw.dcId) dirtyDCs.add(sw.dcId);
-        switchRepairCosts += SWITCH_TIER_CONFIGS[tier].baseCost * SWITCH_REPAIR_COST_FRACTION;
+    const failed = binomialSample(healthy, rate);
+    if (failed > 0) {
+      healthyByTier[tier] = healthy - failed;
+      const baseRepair = SWITCH_TIER_CONFIGS[tier].repairBaseTicks;
+      const repairTime = hotStandbyTicks > 0
+        ? hotStandbyTicks
+        : baseRepair * (1 - repairSpeedBonus);
+      summary.repairBatches.push({ tier, count: failed, ticksRemaining: repairTime });
+      costs += SWITCH_TIER_CONFIGS[tier].baseCost * SWITCH_REPAIR_COST_FRACTION * failed;
+      dirty = true;
+
+      if (tier === 't3') {
+        notifications.push({ title: 'Core Network Failure', message: `Tier-3 core switch failed — potential DC disconnect!`, type: 'danger' });
+      } else if (tier === 't2') {
+        notifications.push({ title: 'Network Switch Failure', message: `Tier-2 spine switch failed — racks may be degraded.`, type: 'warning' });
       }
     }
   }
 
-  for (const sw of repairing) {
-    sw.repairProgress += 1 + opsEff * 0.05;
-    if (sw.repairProgress >= sw.repairTotal) {
-      sw.status = 'healthy';
-      sw.repairProgress = 0;
-      sw.repairTotal = 0;
-      if (sw.dcId) dirtyDCs.add(sw.dcId);
+  const remainingBatches: RepairBatch[] = [];
+  for (const batch of summary.repairBatches) {
+    const newTicks = batch.ticksRemaining - (1 + opsEff * 0.05);
+    if (newTicks <= 0) {
+      healthyByTier[batch.tier] = Math.min(
+        summary.totalByTier[batch.tier] ?? 0,
+        (healthyByTier[batch.tier] ?? 0) + batch.count,
+      );
+      dirty = true;
+    } else {
+      remainingBatches.push({ ...batch, ticksRemaining: newTicks });
     }
   }
 
-  if (dirtyDCs.size > 0) {
-    for (const sw of Object.values(registry)) {
-      if (sw.uplinkIds.length === 0) continue;
-      if (sw.dcId && !dirtyDCs.has(sw.dcId)) continue;
-      let active = 0;
-      for (const upId of sw.uplinkIds) {
-        if (registry[upId]?.status === 'healthy') active++;
-      }
-      sw.activeUplinks = active;
-      sw.effectiveBandwidth = sw.totalUplinks > 0 ? Math.min(1, (active + redundancyBonus) / sw.totalUplinks) : 1;
-    }
-  }
+  if (!dirty) return { summary: { ...summary, repairBatches: remainingBatches }, costs, notifications };
 
-  for (const sw of newlyFailed) {
-    if (sw.tier === 't3') {
-      notifications.push({ title: 'Core Network Failure', message: `Tier-3 core switch failed — potential DC disconnect!`, type: 'danger' });
-    } else if (sw.tier === 't4') {
-      notifications.push({ title: 'Campus Network Failure', message: `Tier-4 campus switch failed — cross-DC degradation!`, type: 'danger' });
-    } else if (sw.tier === 't2') {
-      notifications.push({ title: 'Network Switch Failure', message: `Tier-2 spine switch failed — racks may be degraded.`, type: 'warning' });
-    }
-  }
-
-  return { switchRepairCosts, notifications, dirtyDCs };
+  const updated: DCNetworkSummary = {
+    ...summary,
+    healthyByTier,
+    repairBatches: remainingBatches,
+  };
+  return { summary: recomputeBandwidth(updated, redundancyBonus), costs, notifications };
 }
 
 // --- Interconnect Training Multiplier ---
@@ -476,14 +321,6 @@ export function processInfrastructure(state: GameState, researchBonuses?: Resear
   const hotStandbyTicks = state.research.completedResearch.includes('network-hot-standby') ? 5 : 0;
   const redundancyBonus = state.research.completedResearch.includes('network-redundancy') ? 1 : 0;
 
-  // Mutate registry in-place — infrastructure returns a new state anyway
-  const registry = state.infrastructure.switchRegistry;
-
-  // Process network failures/repairs globally
-  const netResult = processNetworkTick(registry, networkResearchBonus, opsEff, repairSpeedBonus, hotStandbyTicks, redundancyBonus);
-  repairCosts += netResult.switchRepairCosts;
-  if (netResult.notifications.length > 0) notifications.push(...netResult.notifications);
-
   let totalFlops = 0;
   let totalTrainingFlops = 0;
   let totalInferenceFlops = 0;
@@ -541,8 +378,6 @@ export function processInfrastructure(state: GameState, researchBonuses?: Resear
           if (rs.progress >= rs.total) {
             if (rs.phase === 'decommissioning') {
               const installTotal = cohortStageTotal('installation', rs.toSkuId, rs.racksRemaining);
-              // Clear DC topology on retrofit
-              for (const sid of dc.networkSummary.switchIds) delete registry[sid];
               return {
                 ...dc,
                 computeRacksOnline: 0,
@@ -636,10 +471,11 @@ export function processInfrastructure(state: GameState, researchBonuses?: Resear
         // Expand topology for newly onlined racks
         let networkSummary = dc.networkSummary;
         if (racksJustOnlined > 0) {
-          if (networkSummary.switchIds.length === 0) {
-            networkSummary = buildDCTopology(computeRacksOnline, dc.tier, dc.id, registry);
+          const torTotal = networkSummary.totalByTier.tor ?? 0;
+          if (torTotal === 0) {
+            networkSummary = buildDCNetworkSummary(computeRacksOnline, dc.tier);
           } else {
-            networkSummary = expandDCTopology(networkSummary, racksJustOnlined, dc.tier, dc.id, registry);
+            networkSummary = expandDCNetwork(networkSummary, racksJustOnlined, dc.tier);
           }
         }
 
@@ -660,18 +496,20 @@ export function processInfrastructure(state: GameState, researchBonuses?: Resear
               stageTotal: cohortStageTotal('repair', dc.rackSkuId, prodFailures),
               repairCount: 0,
             });
-            networkSummary = shrinkDCTopology(networkSummary, prodFailures, dc.tier, registry);
+            networkSummary = shrinkDCNetwork(networkSummary, prodFailures, dc.tier);
           }
         }
 
         repairCosts += dcRepairCosts;
 
-        // Recompute DC network summary after failures/repairs (only if this DC's switches changed)
-        if (netResult.dirtyDCs.has(dc.id) && networkSummary.switchIds.length > 0) {
-          networkSummary = buildDCSummary(
-            networkSummary.switchIds, networkSummary.networkRackCount, registry,
-          );
-        }
+        // Process per-DC network failures and repairs (aggregate model)
+        const netResult = processNetworkForDC(
+          networkSummary, networkResearchBonus, opsEff,
+          repairSpeedBonus, hotStandbyTicks, redundancyBonus,
+        );
+        networkSummary = netResult.summary;
+        repairCosts += netResult.costs;
+        if (netResult.notifications.length > 0) notifications.push(...netResult.notifications);
 
         // Rackdown: detect recovery (previously disconnected racks now have connectivity)
         const prevDisconnected = dc.networkSummary.racksDisconnected;
@@ -680,7 +518,7 @@ export function processInfrastructure(state: GameState, researchBonuses?: Resear
         if (currDisconnected < prevDisconnected && dc.rackSkuId) {
           const recovered = prevDisconnected - currDisconnected;
           computeRacksOnline -= recovered;
-          networkSummary = shrinkDCTopology(networkSummary, recovered, dc.tier, registry);
+          networkSummary = shrinkDCNetwork(networkSummary, recovered, dc.tier);
           updatedCohorts.push({
             id: `netrecovery-${dc.id}-${Date.now()}`,
             count: recovered, skuId: dc.rackSkuId,
@@ -688,10 +526,6 @@ export function processInfrastructure(state: GameState, researchBonuses?: Resear
             stageTotal: cohortStageTotal('testing', dc.rackSkuId, recovered),
             repairCount: 0,
           });
-          // Recompute summary after shrink
-          networkSummary = buildDCSummary(
-            networkSummary.switchIds, networkSummary.networkRackCount, registry,
-          );
         }
 
         // Compute DC aggregates
@@ -789,8 +623,6 @@ export function processInfrastructure(state: GameState, researchBonuses?: Resear
             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));
-            // Clear topology on retrofit start
-            for (const sid of dc.networkSummary.switchIds) delete registry[sid];
             return {
               ...dc,
               status: 'retrofitting' as const,
@@ -827,7 +659,6 @@ export function processInfrastructure(state: GameState, researchBonuses?: Resear
   return {
     infrastructure: {
       clusters,
-      switchRegistry: registry,
       totalFlops,
       totalTrainingFlops,
       totalInferenceFlops,

packages/shared/src/types/infrastructure.ts

@@ -91,24 +91,6 @@ export interface DataCenter {
 // --- Network Topology (6-Tier Clos) ---
 
 export type SwitchTier = 'tor' | 't1' | 't2' | 't3' | 't4' | 't5';
-export type SwitchStatus = 'healthy' | 'failed' | 'repairing';
-
-export interface NetworkSwitch {
-  id: string;
-  tier: SwitchTier;
-  status: SwitchStatus;
-  dcId: string | null;
-  campusId: string | null;
-  clusterId: string | null;
-  uplinkIds: string[];
-  downlinkIds: string[];
-  activeUplinks: number;
-  totalUplinks: number;
-  effectiveBandwidth: number;
-  repairProgress: number;
-  repairTotal: number;
-}
-
 export interface SwitchTierConfig {
   tier: SwitchTier;
   name: string;
@@ -121,11 +103,17 @@ export interface SwitchTierConfig {
   powerDrawKW: number;
 }
 
+export interface RepairBatch {
+  tier: SwitchTier;
+  count: number;
+  ticksRemaining: number;
+}
+
 export interface DCNetworkSummary {
-  switchIds: string[];
-  networkRackCount: number;
   totalByTier: Partial<Record<SwitchTier, number>>;
   healthyByTier: Partial<Record<SwitchTier, number>>;
+  repairBatches: RepairBatch[];
+  networkRackCount: number;
   racksDisconnected: number;
   racksDegraded: number;
   averageBandwidth: number;
@@ -133,14 +121,12 @@ export interface DCNetworkSummary {
 }
 
 export interface CampusNetworkSummary {
-  switchIds: string[];
   totalT4: number;
   healthyT4: number;
   crossDCBandwidth: number;
 }
 
 export interface ClusterNetworkSummary {
-  switchIds: string[];
   totalT5: number;
   healthyT5: number;
   crossCampusBandwidth: number;
@@ -262,7 +248,6 @@ export interface ClusterCostConfig {
 
 export interface InfrastructureState {
   clusters: Cluster[];
-  switchRegistry: Record<string, NetworkSwitch>;
   totalFlops: number;
   totalTrainingFlops: number;
   totalInferenceFlops: number;
@@ -276,7 +261,6 @@ export interface InfrastructureState {
 
 export const INITIAL_INFRASTRUCTURE: InfrastructureState = {
   clusters: [],
-  switchRegistry: {},
   totalFlops: 0,
   totalTrainingFlops: 0,
   totalInferenceFlops: 0,