diff --git a/packages/sdk/src/actions/index.ts b/packages/sdk/src/actions/index.ts
index c378a6d6..b3ef94e3 100644
--- a/packages/sdk/src/actions/index.ts
+++ b/packages/sdk/src/actions/index.ts
@@ -38,6 +38,7 @@ export {
   type CompactionEvent,
   type CompactionStartEvent,
   type CompactionEndEvent,
+  type AgentErrorEvent,
   type ContentBlock,
   type TextContent,
   type ThinkingContent,
diff --git a/packages/sdk/src/actions/stream.ts b/packages/sdk/src/actions/stream.ts
index c0249353..19aa9482 100644
--- a/packages/sdk/src/actions/stream.ts
+++ b/packages/sdk/src/actions/stream.ts
@@ -45,16 +45,22 @@ export type CompactionEndEvent = {
 /** Union of all compaction events */
 export type CompactionEvent = CompactionStartEvent | CompactionEndEvent;
 
+/** Emitted when the agent encounters an error (LLM failure, quota exceeded, etc.) */
+export type AgentErrorEvent = {
+  type: "agent_error";
+  error: string;
+};
+
 // --- Stream event types ---
 
 /**
- * Hub forwards AgentEvent from pi-agent-core and CompactionEvent as-is.
- * StreamPayload wraps them with routing metadata.
+ * Hub forwards AgentEvent from pi-agent-core, CompactionEvent,
+ * and AgentErrorEvent as-is. StreamPayload wraps them with routing metadata.
  */
 export interface StreamPayload {
   streamId: string;
   agentId: string;
-  event: AgentEvent | CompactionEvent;
+  event: AgentEvent | CompactionEvent | AgentErrorEvent;
 }
 
 /** Extract thinking/reasoning content from an AgentEvent that carries a message */