diff --git a/src/agents/system-prompt.ts b/src/agents/system-prompt.ts
index b1fde3732..71a34231c 100644
--- a/src/agents/system-prompt.ts
+++ b/src/agents/system-prompt.ts
@@ -166,6 +166,8 @@ export function buildAgentSystemPrompt(params: {
   defaultThinkLevel?: ThinkLevel;
   reasoningLevel?: ReasoningLevel;
   extraSystemPrompt?: string;
+  /** Event-sourced context from NATS (formatted text block). */
+  eventContextHint?: string;
   ownerNumbers?: string[];
   reasoningTagHint?: boolean;
   toolNames?: string[];
@@ -551,6 +553,11 @@ export function buildAgentSystemPrompt(params: {
     }
   }
 
+  // Event-sourced context (from NATS JetStream)
+  if (params.eventContextHint) {
+    lines.push("## Event-Sourced Memory", "", params.eventContextHint, "");
+  }
+
   // Skip silent replies for subagent/none modes
   if (!isMinimal) {
     lines.push(