diff --git a/packages/coding-agent/src/core/extensions/loader.ts b/packages/coding-agent/src/core/extensions/loader.ts
index afc23069..03042a87 100644
--- a/packages/coding-agent/src/core/extensions/loader.ts
+++ b/packages/coding-agent/src/core/extensions/loader.ts
@@ -313,7 +313,7 @@ async function loadExtensionWithBun(
 			setFlagValue,
 		} = createExtensionAPI(handlers, tools, cwd, extensionPath, eventBus, sharedUI);
 
-		factory(api);
+		await factory(api);
 
 		return {
 			extension: {
@@ -401,7 +401,7 @@ async function loadExtension(
 			setFlagValue,
 		} = createExtensionAPI(handlers, tools, cwd, extensionPath, eventBus, sharedUI);
 
-		factory(api);
+		await factory(api);
 
 		return {
 			extension: {
@@ -436,13 +436,13 @@ async function loadExtension(
 /**
  * Create a LoadedExtension from an inline factory function.
  */
-export function loadExtensionFromFactory(
+export async function loadExtensionFromFactory(
 	factory: ExtensionFactory,
 	cwd: string,
 	eventBus: EventBus,
 	sharedUI: { ui: ExtensionUIContext; hasUI: boolean },
 	name = "<inline>",
-): LoadedExtension {
+): Promise<LoadedExtension> {
 	const handlers = new Map<string, HandlerFn[]>();
 	const tools = new Map<string, RegisteredTool>();
 	const {
@@ -464,7 +464,7 @@ export function loadExtensionFromFactory(
 		setFlagValue,
 	} = createExtensionAPI(handlers, tools, cwd, name, eventBus, sharedUI);
 
-	factory(api);
+	await factory(api);
 
 	return {
 		path: name,
diff --git a/packages/coding-agent/src/core/extensions/types.ts b/packages/coding-agent/src/core/extensions/types.ts
index ad7b8540..96e095d2 100644
--- a/packages/coding-agent/src/core/extensions/types.ts
+++ b/packages/coding-agent/src/core/extensions/types.ts
@@ -641,8 +641,8 @@ export interface ExtensionAPI {
 	events: EventBus;
 }
 
-/** Extension factory function type. */
-export type ExtensionFactory = (pi: ExtensionAPI) => void;
+/** Extension factory function type. Supports both sync and async initialization. */
+export type ExtensionFactory = (pi: ExtensionAPI) => void | Promise<void>;
 
 // ============================================================================
 // Loaded Extension Types
diff --git a/packages/coding-agent/src/core/sdk.ts b/packages/coding-agent/src/core/sdk.ts
index 6440415a..34b456ad 100644
--- a/packages/coding-agent/src/core/sdk.ts
+++ b/packages/coding-agent/src/core/sdk.ts
@@ -488,7 +488,7 @@ export async function createAgentSession(options: CreateAgentSessionOptions = {}
 		};
 		for (let i = 0; i < options.extensions.length; i++) {
 			const factory = options.extensions[i];
-			const loaded = loadExtensionFromFactory(factory, cwd, eventBus, uiHolder, `<inline-${i}>`);
+			const loaded = await loadExtensionFromFactory(factory, cwd, eventBus, uiHolder, `<inline-${i}>`);
 			extensionsResult.extensions.push(loaded);
 		}
 		// Extend setUIContext to update inline extensions too