packages/ai: ignore null chunks in openai-completions streams (#2466)

packages/ai/src/providers/openai-completions.ts

@@ -127,6 +127,8 @@ export const streamOpenAICompletions: StreamFunction<"openai-completions", OpenA
 			};
 
 			for await (const chunk of openaiStream) {
+				if (!chunk || typeof chunk !== "object") continue;
+
 				// OpenAI documents ChatCompletionChunk.id as the unique chat completion identifier,
 				// and each chunk in a streamed completion carries the same id.
 				output.responseId ||= chunk.id;
@@ -134,7 +136,7 @@ export const streamOpenAICompletions: StreamFunction<"openai-completions", OpenA
 					output.usage = parseChunkUsage(chunk.usage, model);
 				}
 
-				const choice = chunk.choices?.[0];
+				const choice = Array.isArray(chunk.choices) ? chunk.choices[0] : undefined;
 				if (!choice) continue;
 
 				// Fallback: some providers (e.g., Moonshot) return usage

packages/ai/test/openai-completions-tool-choice.test.ts

@@ -7,15 +7,19 @@ import type { Tool } from "../src/types.js";
 const mockState = vi.hoisted(() => ({
 	lastParams: undefined as unknown,
 	chunks: undefined as
-		| Array<{
-				choices: Array<{ delta: Record<string, unknown>; finish_reason: string | null }>;
-				usage?: {
-					prompt_tokens: number;
-					completion_tokens: number;
-					prompt_tokens_details: { cached_tokens: number };
-					completion_tokens_details: { reasoning_tokens: number };
-				};
-		  }>
+		| Array<
+				| null
+				| {
+						id?: string;
+						choices?: Array<{ delta: Record<string, unknown>; finish_reason: string | null; usage?: unknown }>;
+						usage?: {
+							prompt_tokens: number;
+							completion_tokens: number;
+							prompt_tokens_details: { cached_tokens: number };
+							completion_tokens_details: { reasoning_tokens: number };
+						};
+				  }
+		  >
 		| undefined,
 }));
 
@@ -234,6 +238,48 @@ describe("openai-completions tool_choice", () => {
 		expect(response.errorMessage).toBe("Provider finish_reason: network_error");
 	});
 
+	it("ignores null stream chunks from openai-compatible providers", async () => {
+		mockState.chunks = [
+			null,
+			{
+				id: "chatcmpl-test",
+				choices: [{ delta: { content: "OK" }, finish_reason: null }],
+			},
+			{
+				id: "chatcmpl-test",
+				choices: [{ delta: {}, finish_reason: "stop" }],
+				usage: {
+					prompt_tokens: 3,
+					completion_tokens: 1,
+					prompt_tokens_details: { cached_tokens: 0 },
+					completion_tokens_details: { reasoning_tokens: 0 },
+				},
+			},
+		];
+
+		const { compat: _compat, ...baseModel } = getModel("openai", "gpt-4o-mini")!;
+		const model = { ...baseModel, api: "openai-completions" } as const;
+		const response = await streamSimple(
+			model,
+			{
+				messages: [
+					{
+						role: "user",
+						content: "Reply with exactly OK",
+						timestamp: Date.now(),
+					},
+				],
+			},
+			{ apiKey: "test" },
+		).result();
+
+		expect(response.stopReason).toBe("stop");
+		expect(response.errorMessage).toBeUndefined();
+		expect(response.responseId).toBe("chatcmpl-test");
+		expect(response.usage.totalTokens).toBe(4);
+		expect(response.content).toEqual([{ type: "text", text: "OK" }]);
+	});
+
 	it("uses OpenRouter reasoning object instead of reasoning_effort", async () => {
 		const model = getModel("openrouter", "deepseek/deepseek-r1")!;
 		let payload: unknown;