diff --git a/packages/agent/src/server/agent-server.ts b/packages/agent/src/server/agent-server.ts
index 0d2a8fc48..f1b12dc2d 100644
--- a/packages/agent/src/server/agent-server.ts
+++ b/packages/agent/src/server/agent-server.ts
@@ -1629,7 +1629,7 @@ export class AgentServer {
     prUrl?: string | null,
     slackThreadUrl?: string | null,
   ): string | { append: string } {
-    const cloudAppend = this.buildCloudSystemPrompt(prUrl, slackThreadUrl);
+    const cloudAppend = `${this.buildCloudSystemPrompt(prUrl, slackThreadUrl)}\n${this.buildMemoryInstructions()}`;
     const userPrompt = this.config.claudeCode?.systemPrompt;
 
     // String override: combine user prompt with cloud instructions
@@ -1696,6 +1696,28 @@ export class AgentServer {
     );
   }
 
+  /**
+   * Guidance for the shared, semantically-searchable PostHog memory store exposed through the
+   * `memory` MCP tool. Appended to every cloud-run system prompt so cloud agents recall durable
+   * context across runs and persist new learnings — the same memory store Max/PostHog AI uses.
+   *
+   * Applies to both cloud runtimes: `_doInitializeSession` passes the PostHog MCP server (which
+   * carries the `memory` tool) via `newSession({ mcpServers })` for Claude and Codex alike, and
+   * the Codex adapter forwards those servers to the Codex CLI, so the tool is callable on both.
+   * `buildCodexInstructions` reusing this text for Codex runs is therefore intentional.
+   */
+  private buildMemoryInstructions(): string {
+    return `
+# Persistent Memory
+You have access to PostHog's persistent memory through the \`memory\` MCP tool — a shared,
+semantically-searchable store of durable facts about this user, their company, product, and
+preferences (the same memories used across PostHog AI). Memories persist across runs, so:
+- Before non-trivial work, recall context with the \`memory\` tool using \`action: "query"\` (semantic search) to surface durable facts, decisions, and prior discussions.
+- When you learn something durable — product setup, conventions, definitions, preferences, decisions — store it with \`action: "create"\`. Do this pre-emptively; you don't need to be asked. Query first to avoid duplicates.
+- Use \`action: "update"\`/\`"delete"\` to keep memories accurate, and \`action: "list_metadata_keys"\` to keep metadata tags consistent.
+- Memories are for durable facts, not transient task state. New memories become searchable once their embedding is processed.`;
+  }
+
   private buildCloudSystemPrompt(
     prUrl?: string | null,
     slackThreadUrl?: string | null,