opt: Enhance OpenAiHandler to diagnose request issues and handle empty streams (#1702)

.changeset/forty-timers-kick.md

@@ -0,0 +1,5 @@
+---
+"claude-dev": patch
+---
+
+opt: Enhance OpenAiHandler to diagnose request issues and handle empty streams

src/api/providers/openai.ts

@@ -28,6 +28,65 @@ export class OpenAiHandler implements ApiHandler {
 		}
 	}
 
+	private async diagnoseRequestProblem(
+		modelId: string,
+		messages: OpenAI.Chat.ChatCompletionMessageParam[],
+		apiKey: string,
+		baseURL: string,
+	) {
+		const url = `${baseURL}/chat/completions`
+
+		try {
+			const response = await fetch(url, {
+				method: "POST",
+				headers: {
+					"Content-Type": "application/json",
+					Authorization: `Bearer ${apiKey}`,
+				},
+				body: JSON.stringify({
+					model: modelId,
+					messages: messages,
+					temperature: 0,
+					stream: true,
+				}),
+			})
+
+			if (!response.ok) {
+				return `HTTP error! status: ${response.status}, statusText: ${response.statusText}`
+			}
+
+			const responseData = await response.json()
+			return responseData
+		} catch (error) {
+			return error instanceof Error ? error.message : String(error)
+		}
+	}
+
+	private async *handleChunk(chunk: OpenAI.Chat.Completions.ChatCompletionChunk): ApiStream {
+		const delta = chunk.choices[0]?.delta
+		if (delta?.content) {
+			yield {
+				type: "text",
+				text: delta.content,
+			}
+		}
+
+		if (delta && "reasoning_content" in delta && delta.reasoning_content) {
+			yield {
+				type: "reasoning",
+				reasoning: (delta.reasoning_content as string | undefined) || "",
+			}
+		}
+
+		if (chunk.usage) {
+			yield {
+				type: "usage",
+				inputTokens: chunk.usage.prompt_tokens || 0,
+				outputTokens: chunk.usage.completion_tokens || 0,
+			}
+		}
+	}
+
 	@withRetry()
 	async *createMessage(systemPrompt: string, messages: Anthropic.Messages.MessageParam[]): ApiStream {
 		const modelId = this.options.openAiModelId ?? ""
@@ -49,29 +108,30 @@ export class OpenAiHandler implements ApiHandler {
 			stream: true,
 			stream_options: { include_usage: true },
 		})
-		for await (const chunk of stream) {
-			const delta = chunk.choices[0]?.delta
-			if (delta?.content) {
-				yield {
-					type: "text",
-					text: delta.content,
-				}
-			}
 
-			if (delta && "reasoning_content" in delta && delta.reasoning_content) {
-				yield {
-					type: "reasoning",
-					reasoning: (delta.reasoning_content as string | undefined) || "",
-				}
-			}
+		const [validationStream, contentStream] = stream.tee()
 
-			if (chunk.usage) {
-				yield {
-					type: "usage",
-					inputTokens: chunk.usage.prompt_tokens || 0,
-					outputTokens: chunk.usage.completion_tokens || 0,
-				}
-			}
+		// Check the first chunk to detect potential stream issues early
+		// This helps to provide better error messages for cases like:
+		// https://github.com/cline/cline/issues/1662
+		// where the stream appears valid but contains no actual data
+		const firstChunk = await validationStream[Symbol.asyncIterator]().next()
+		if (firstChunk.done || !firstChunk.value) {
+			// Make an additional request to get detailed error information
+			// This gives us more context about what went wrong with the API call
+			const errorResponse = await this.diagnoseRequestProblem(
+				modelId,
+				openAiMessages,
+				this.client.apiKey,
+				this.client.baseURL,
+			)
+			throw new Error(`Stream empty. Error details: ${JSON.stringify(errorResponse)}`)
+		}
+
+		yield* this.handleChunk(firstChunk.value)
+
+		for await (const chunk of contentStream) {
+			yield* this.handleChunk(chunk)
 		}
 	}