fix: add proxy support for Gemini API client

- Created proxy-aware fetch utility that respects HTTP_PROXY/HTTPS_PROXY env vars
- Falls back to axios when native fetch fails with proxy settings
- Updated GeminiHandler constructor to setup proxy-aware fetch
- This fixes the 'TypeError: fetch failed sending request' error when behind a proxy

Fixes #9465

src/api/providers/gemini.ts

@@ -22,6 +22,7 @@ import { getModelParams } from "../transform/model-params"
 
 import type { SingleCompletionHandler, ApiHandlerCreateMessageMetadata } from "../index"
 import { BaseProvider } from "./base-provider"
+import { setupGlobalProxyFetch, restoreOriginalFetch } from "../../utils/proxy-fetch"
 
 type GeminiHandlerOptions = ApiHandlerOptions & {
 	isVertex?: boolean
@@ -43,6 +44,14 @@ export class GeminiHandler extends BaseProvider implements SingleCompletionHandl
 		const location = this.options.vertexRegion ?? "not-provided"
 		const apiKey = this.options.geminiApiKey ?? "not-provided"
 
+		// Setup proxy-aware fetch for GoogleGenAI client
+		// This ensures that the Gemini API client respects system proxy settings
+		try {
+			setupGlobalProxyFetch()
+		} catch (error) {
+			console.warn("Failed to setup proxy-aware fetch for Gemini:", error)
+		}
+
 		this.client = this.options.vertexJsonCredentials
 			? new GoogleGenAI({
 					vertexai: true,

src/utils/proxy-fetch.ts

@@ -0,0 +1,143 @@
+import * as http from "node:http"
+import * as https from "node:https"
+import { URL } from "node:url"
+
+/**
+ * Gets the HTTP(S) agent configured with proxy settings if needed
+ * This checks environment variables for proxy configuration
+ */
+export function getProxyAgent(): { httpAgent?: http.Agent; httpsAgent?: https.Agent } {
+	const httpProxy = process.env.HTTP_PROXY || process.env.http_proxy
+	const httpsProxy = process.env.HTTPS_PROXY || process.env.https_proxy
+	const noProxy = process.env.NO_PROXY || process.env.no_proxy
+
+	const agents: { httpAgent?: http.Agent; httpsAgent?: https.Agent } = {}
+
+	// Configure HTTP agent with proxy if needed
+	if (httpProxy) {
+		try {
+			const HttpsProxyAgent = require("https-proxy-agent").HttpsProxyAgent
+			agents.httpAgent = new HttpsProxyAgent(httpProxy)
+		} catch (error) {
+			// If https-proxy-agent is not available, we'll try another approach
+			console.warn("https-proxy-agent not available, proxy support may be limited")
+		}
+	}
+
+	// Configure HTTPS agent with proxy if needed
+	if (httpsProxy) {
+		try {
+			const HttpsProxyAgent = require("https-proxy-agent").HttpsProxyAgent
+			agents.httpsAgent = new HttpsProxyAgent(httpsProxy)
+		} catch (error) {
+			// If https-proxy-agent is not available, we'll try another approach
+			console.warn("https-proxy-agent not available, proxy support may be limited")
+		}
+	}
+
+	return agents
+}
+
+/**
+ * Creates a custom fetch that respects proxy settings
+ * Falls back to axios if native fetch fails with proxy
+ */
+export function createProxyAwareFetch(): typeof fetch {
+	const httpProxy = process.env.HTTP_PROXY || process.env.http_proxy
+	const httpsProxy = process.env.HTTPS_PROXY || process.env.https_proxy
+
+	// If no proxy is configured, return the native fetch
+	if (!httpProxy && !httpsProxy) {
+		return fetch
+	}
+
+	// Create a custom fetch that falls back to axios for proxy support
+	return async (input: RequestInfo | URL, init?: RequestInit): Promise<Response> => {
+		const url = typeof input === "string" ? input : input instanceof URL ? input.href : input.url
+
+		try {
+			// First try native fetch
+			return await fetch(input, init)
+		} catch (fetchError) {
+			// If fetch fails and we have proxy settings, try axios as fallback
+			console.warn("Native fetch failed, attempting with axios for proxy support:", (fetchError as Error).message)
+
+			try {
+				const axios = require("axios")
+
+				// Convert RequestInit to axios config
+				const axiosConfig: any = {
+					url,
+					method: init?.method || "GET",
+					headers: init?.headers || {},
+					data: init?.body,
+					responseType: "arraybuffer",
+					// Let axios handle proxy from environment variables
+					proxy: false, // Disable axios default proxy to use env vars
+				}
+
+				// Configure proxy if needed
+				if (httpProxy || httpsProxy) {
+					const isHttps = url.toLowerCase().startsWith("https://")
+					const proxyUrl = isHttps ? httpsProxy || httpProxy : httpProxy
+
+					if (proxyUrl) {
+						const proxyUrlObj = new URL(proxyUrl)
+						axiosConfig.proxy = {
+							protocol: proxyUrlObj.protocol.replace(":", ""),
+							host: proxyUrlObj.hostname,
+							port: parseInt(proxyUrlObj.port) || (proxyUrlObj.protocol === "https:" ? 443 : 80),
+							auth: proxyUrlObj.username
+								? {
+										username: proxyUrlObj.username,
+										password: proxyUrlObj.password,
+									}
+								: undefined,
+						}
+					}
+				}
+
+				const response = await axios(axiosConfig)
+
+				// Convert axios response to fetch Response
+				return new Response(response.data, {
+					status: response.status,
+					statusText: response.statusText,
+					headers: new Headers(response.headers as HeadersInit),
+				})
+			} catch (axiosError) {
+				// If axios also fails, throw the original fetch error
+				console.error("Both fetch and axios failed:", axiosError)
+				throw fetchError
+			}
+		}
+	}
+}
+
+/**
+ * Sets up global fetch to use proxy-aware implementation
+ * This should be called before creating API clients that use fetch
+ */
+export function setupGlobalProxyFetch(): void {
+	const proxyFetch = createProxyAwareFetch()
+
+	// Only override if we have a custom implementation
+	if (proxyFetch !== fetch) {
+		;(globalThis as any).fetch = proxyFetch
+	}
+}
+
+/**
+ * Restores the original fetch implementation
+ */
+export function restoreOriginalFetch(): void {
+	// Store original fetch if not already stored
+	if (!(globalThis as any).__originalFetch && globalThis.fetch) {
+		;(globalThis as any).__originalFetch = globalThis.fetch
+	}
+
+	// Restore original fetch
+	if ((globalThis as any).__originalFetch) {
+		;(globalThis as any).fetch = (globalThis as any).__originalFetch
+	}
+}