Refactor tool execution to use event-based generator

Changed executeToolCalls to yield structured ToolExecutionEvent objects, separating 'update' and 'complete' events. Updated runMcpFlow to handle the new event types and improved error handling and logging for missing execution summaries.

Author: gary149

src/lib/server/textGeneration/mcp/runMcpFlow.ts

@@ -334,14 +334,19 @@ export async function* runMcpFlow({
 			});
 
 			let executionResult: ToolCallExecutionResult | undefined;
-			let iterResult = await executionGenerator.next();
-			while (!iterResult.done) {
-				yield iterResult.value;
-				iterResult = await executionGenerator.next();
+			for await (const event of executionGenerator) {
+				if (event.type === "update") {
+					yield event.update;
+				} else if (event.type === "complete") {
+					executionResult = event.summary;
+				}
 			}
-			executionResult = iterResult.value;
 
 			if (!executionResult) {
+				logger.warn(
+					{ serverCount: servers.length, callCount: normalizedCalls.length },
+					"[mcp] executeToolCalls completed without summary"
+				);
 				return false;
 			}
 

src/lib/server/textGeneration/mcp/toolInvocation.ts

@@ -40,6 +40,10 @@ export interface ToolCallExecutionResult {
 	finalAnswer?: { text: string; interrupted: boolean };
 }
 
+export type ToolExecutionEvent =
+	| { type: "update"; update: MessageUpdate }
+	| { type: "complete"; summary: ToolCallExecutionResult };
+
 const serverMap = (servers: McpServerConfig[]): Map<string, McpServerConfig> => {
 	const map = new Map<string, McpServerConfig>();
 	for (const server of servers) {
@@ -57,7 +61,7 @@ export async function* executeToolCalls({
 	parseArgs,
 	toPrimitive,
 	collectToolOutputSources,
-}: ExecuteToolCallsParams): AsyncGenerator<MessageUpdate, ToolCallExecutionResult, undefined> {
+}: ExecuteToolCallsParams): AsyncGenerator<ToolExecutionEvent, void, undefined> {
 	const toolMessages: ChatCompletionMessageParam[] = [];
 	const toolRuns: ToolRun[] = [];
 	const serverLookup = serverMap(servers);
@@ -75,48 +79,68 @@ export async function* executeToolCalls({
 		}
 
 		yield {
-			type: MessageUpdateType.Tool,
-			subtype: MessageToolUpdateType.Call,
-			uuid,
-			call: { name: call.name, parameters: parametersClean },
+			type: "update",
+			update: {
+				type: MessageUpdateType.Tool,
+				subtype: MessageToolUpdateType.Call,
+				uuid,
+				call: { name: call.name, parameters: parametersClean },
+			},
 		};
 
 		yield {
-			type: MessageUpdateType.Tool,
-			subtype: MessageToolUpdateType.ETA,
-			uuid,
-			eta: 10,
+			type: "update",
+			update: {
+				type: MessageUpdateType.Tool,
+				subtype: MessageToolUpdateType.ETA,
+				uuid,
+				eta: 10,
+			},
 		};
 
 		if (!mappingEntry) {
 			const message = `Unknown MCP function: ${call.name}`;
 			yield {
-				type: MessageUpdateType.Tool,
-				subtype: MessageToolUpdateType.Error,
-				uuid,
-				message,
+				type: "update",
+				update: {
+					type: MessageUpdateType.Tool,
+					subtype: MessageToolUpdateType.Error,
+					uuid,
+					message,
+				},
 			};
-			return {
-				toolMessages,
-				toolRuns,
-				finalAnswer: { text: message, interrupted: false },
+			yield {
+				type: "complete",
+				summary: {
+					toolMessages,
+					toolRuns,
+					finalAnswer: { text: message, interrupted: false },
+				},
 			};
+			return;
 		}
 
 		const serverConfig = serverLookup.get(mappingEntry.server);
 		if (!serverConfig) {
 			const message = `Unknown MCP server: ${mappingEntry.server}`;
 			yield {
-				type: MessageUpdateType.Tool,
-				subtype: MessageToolUpdateType.Error,
-				uuid,
-				message,
+				type: "update",
+				update: {
+					type: MessageUpdateType.Tool,
+					subtype: MessageToolUpdateType.Error,
+					uuid,
+					message,
+				},
 			};
-			return {
-				toolMessages,
-				toolRuns,
-				finalAnswer: { text: message, interrupted: false },
+			yield {
+				type: "complete",
+				summary: {
+					toolMessages,
+					toolRuns,
+					finalAnswer: { text: message, interrupted: false },
+				},
 			};
+			return;
 		}
 
 		try {
@@ -132,19 +156,22 @@ export async function* executeToolCalls({
 			);
 
 			yield {
-				type: MessageUpdateType.Tool,
-				subtype: MessageToolUpdateType.Result,
-				uuid,
-				result: {
-					status: ToolResultStatus.Success,
-					call: { name: call.name, parameters: parametersClean },
-					outputs: [
-						{
-							content: output,
-							sources: outputSources,
-						},
-					],
-					display: true,
+				type: "update",
+				update: {
+					type: MessageUpdateType.Tool,
+					subtype: MessageToolUpdateType.Result,
+					uuid,
+					result: {
+						status: ToolResultStatus.Success,
+						call: { name: call.name, parameters: parametersClean },
+						outputs: [
+							{
+								content: output,
+								sources: outputSources,
+							},
+						],
+						display: true,
+					},
 				},
 			};
 
@@ -157,18 +184,28 @@ export async function* executeToolCalls({
 				"[mcp] tool call failed"
 			);
 			yield {
-				type: MessageUpdateType.Tool,
-				subtype: MessageToolUpdateType.Error,
-				uuid,
-				message,
+				type: "update",
+				update: {
+					type: MessageUpdateType.Tool,
+					subtype: MessageToolUpdateType.Error,
+					uuid,
+					message,
+				},
 			};
-			return {
-				toolMessages,
-				toolRuns,
-				finalAnswer: { text: `MCP error: ${message}`, interrupted: false },
+			yield {
+				type: "complete",
+				summary: {
+					toolMessages,
+					toolRuns,
+					finalAnswer: { text: `MCP error: ${message}`, interrupted: false },
+				},
 			};
+			return;
 		}
 	}
 
-	return { toolMessages, toolRuns };
+	yield {
+		type: "complete",
+		summary: { toolMessages, toolRuns },
+	};
 }