diff --git a/src/vs/platform/agentHost/node/agentHostMain.ts b/src/vs/platform/agentHost/node/agentHostMain.ts
index 7df7461682c..04a779fc59e 100644
--- a/src/vs/platform/agentHost/node/agentHostMain.ts
+++ b/src/vs/platform/agentHost/node/agentHostMain.ts
@@ -173,6 +173,9 @@ async function startWebSocketServer(agentService: AgentService, logService: ILog
 		handleBrowseDirectory(uri) {
 			return agentService.browseDirectory(URI.parse(uri));
 		},
+		handleWriteFile(params) {
+			return agentService.writeFile(params);
+		},
 		async handleRestoreSession(session) {
 			return agentService.restoreSession(URI.parse(session));
 		},
diff --git a/src/vs/platform/agentHost/test/node/protocolServerHandler.test.ts b/src/vs/platform/agentHost/test/node/protocolServerHandler.test.ts
index 9a87a5edb02..f4e2fae680e 100644
--- a/src/vs/platform/agentHost/test/node/protocolServerHandler.test.ts
+++ b/src/vs/platform/agentHost/test/node/protocolServerHandler.test.ts
@@ -77,6 +77,7 @@ class MockSideEffectHandler implements IProtocolSideEffectHandler {
 	async handleListSessions(): Promise<ISessionSummary[]> { return []; }
 	async handleRestoreSession(_session: string): Promise<void> { }
 	handleGetResourceMetadata() { return { resources: [] }; }
+	handleWriteFile() { return Promise.resolve({}); }
 	async handleAuthenticate(_params: { resource: string; token: string }) { return { authenticated: true }; }
 	async handleBrowseDirectory(uri: string): Promise<{ entries: { name: string; type: 'file' | 'directory' }[] }> {
 		this.browsedUris.push(URI.parse(uri));