diff --git a/simulation-client/src/config/index.js b/simulation-client/src/config/index.js
index 80fb317..bf473fd 100644
--- a/simulation-client/src/config/index.js
+++ b/simulation-client/src/config/index.js
@@ -64,6 +64,15 @@ const config = {
     errorInjection: {
       enabled: (process.env.ERROR_INJECTION_ENABLED || 'true') === 'true',
       probability: parseFloat(process.env.ERROR_INJECTION_PROBABILITY) || 0.05
+    },
+
+    // Scheduled error spikes: crank error probability at fixed minutes each hour
+    // so every 30-min demo window has a visible spike to investigate.
+    errorSpike: {
+      enabled: (process.env.ERROR_SPIKE_ENABLED || 'true') === 'true',
+      probability: parseFloat(process.env.ERROR_SPIKE_PROBABILITY) || 0.6,
+      minuteMarks: (process.env.ERROR_SPIKE_MINUTES || '10,40').split(',').map(Number),
+      durationMinutes: parseInt(process.env.ERROR_SPIKE_DURATION) || 2
     }
   },
 
diff --git a/simulation-client/src/workflows/SimulationManager.js b/simulation-client/src/workflows/SimulationManager.js
index 43b972e..2f17c85 100644
--- a/simulation-client/src/workflows/SimulationManager.js
+++ b/simulation-client/src/workflows/SimulationManager.js
@@ -295,6 +295,7 @@ class SimulationManager {
       runtimeMs: runtime,
       activeSessions: this.activeSessions.size,
       burstActive: this.burstActive,
+      errorSpikeActive: this.isErrorSpikeActive(),
       currentConcurrency: this.getCurrentConcurrency(),
       totalSessions: this.metrics.totalSessions,
       successfulSessions: this.metrics.successfulSessions,
@@ -311,6 +312,13 @@ class SimulationManager {
     };
   }
 
+  isErrorSpikeActive() {
+    const spike = config.simulation.errorSpike;
+    if (!spike.enabled) return false;
+    const minute = new Date().getMinutes();
+    return spike.minuteMarks.some(m => minute >= m && minute < m + spike.durationMinutes);
+  }
+
   delay(ms) {
     return new Promise(resolve => setTimeout(resolve, ms));
   }
diff --git a/simulation-client/src/workflows/UserWorkflow.js b/simulation-client/src/workflows/UserWorkflow.js
index d08aeaa..daf41a1 100644
--- a/simulation-client/src/workflows/UserWorkflow.js
+++ b/simulation-client/src/workflows/UserWorkflow.js
@@ -512,7 +512,16 @@ class UserWorkflow {
   // (The gateway FaultInjectionFilter adds independent 500/503 noise.)
   async generateErrorTraffic(user) {
     if (!config.simulation.errorInjection.enabled) return;
-    if (Math.random() >= config.simulation.errorInjection.probability) return;
+
+    let effectiveProbability = config.simulation.errorInjection.probability;
+    const spike = config.simulation.errorSpike;
+    if (spike.enabled) {
+      const minute = new Date().getMinutes();
+      if (spike.minuteMarks.some(m => minute >= m && minute < m + spike.durationMinutes)) {
+        effectiveProbability = spike.probability;
+      }
+    }
+    if (Math.random() >= effectiveProbability) return;
 
     const account = user.accounts && user.accounts.length > 0 ? user.accounts[0] : null;