Handle AI SDK tool-call args

Author: Alex-yang00

src/api/transform/__tests__/ai-sdk.spec.ts

@@ -441,6 +441,25 @@ describe("AI SDK conversion utilities", () => {
 			})
 		})
 
+		it("processes complete tool-call chunks with args", () => {
+			const part = {
+				type: "tool-call" as const,
+				toolCallId: "call_1",
+				toolName: "attempt_completion",
+				input: undefined,
+				args: { result: "done" },
+			}
+			const chunks = [...processAiSdkStreamPart(part as any)]
+
+			expect(chunks).toHaveLength(1)
+			expect(chunks[0]).toEqual({
+				type: "tool_call",
+				id: "call_1",
+				name: "attempt_completion",
+				arguments: '{"result":"done"}',
+			})
+		})
+
 		it("processes source chunks with URL", () => {
 			const part = {
 				type: "source" as const,

src/api/transform/ai-sdk.ts

@@ -185,6 +185,17 @@ export function convertToolsForAiSdk(
  */
 type ExtendedStreamPart = TextStreamPart<any> | { type: "text"; text: string } | { type: "reasoning"; text: string }
 
+function stringifyToolInput(part: Extract<TextStreamPart<any>, { type: "tool-call" }>) {
+	const input =
+		"input" in part && part.input !== undefined
+			? part.input
+			: "args" in part
+				? (part as { args: unknown }).args
+				: {}
+
+	return typeof input === "string" ? input : JSON.stringify(input)
+}
+
 /**
  * Process a single AI SDK stream part and yield the appropriate ApiStreamChunk(s).
  * This generator handles all TextStreamPart types and converts them to the
@@ -234,7 +245,7 @@ export function* processAiSdkStreamPart(part: ExtendedStreamPart): Generator<Api
 				type: "tool_call",
 				id: part.toolCallId,
 				name: part.toolName,
-				arguments: typeof part.input === "string" ? part.input : JSON.stringify(part.input),
+				arguments: stringifyToolInput(part),
 			}
 			break