I was halfway through shipping a React refactor last Tuesday when my Cursor IDE threw this at me:
ConnectionError: Request timed out after 30000ms
at AnthropicProvider.streamChat (anthropic-provider.ts:142)
at CursorAgent.handleRequest (agent.ts:88)
code: 'ETIMEDOUT'If you have ever stared at a 30-second spinner while Cursor tried to reach Anthropic's official endpoint from mainland China, you know the pain. The cursor is frozen, the model dropdown is greyed out, and your sprint demo is in an hour. The fix is to switch the underlying provider to a relay that does the heavy lifting for you. After a weekend of testing three options, I settled on HolySheep AI as the relay, which cut my bill to roughly one third of the official rate while keeping the official Anthropic Claude plugin working inside Cursor with no code changes. This guide is the exact notes I wrote for my team.
What you are building
You will keep the official Anthropic plugin enabled inside Cursor IDE, but point it at a local OpenAI-compatible base URL. HolySheep's gateway normalizes Anthropic-format requests to the Claude API, so Cursor thinks it is talking to Anthropic while you are actually talking to HolySheep's edge. The end result: same Tab-completion quality, faster time-to-first-token, and a bill that is 70%+ lower.
Who this setup is for (and who it is not)
For
- Engineers in mainland China or Southeast Asia where api.anthropic.com is blocked or unstable.
- Solo developers and indie hackers who want Claude Sonnet 4.5 quality without the $15 per million output tokens burn rate.
- Bootstrapped teams that need predictable monthly costs in RMB.
- Anyone who wants WeChat or Alipay invoicing instead of a US credit card.
Not for
- Enterprises that require a signed BAA with Anthropic directly.
- Workflows that need zero data residency outside a US/EU region (verify HolySheep's data routing first).
- Users who only need GPT-4o-class quality and are happy paying OpenAI's rack rate.
Prerequisites
- Cursor IDE version 0.42 or newer.
- An active HolySheep account. Sign up here — registration comes with free credits, no card required.
- Your HolySheep API key (starts with
sk-hs-...). Generate it under Dashboard → API Keys. - Optional:
curlandopensslfor the smoke test in Step 4.
Step 1 — Install the official Anthropic plugin in Cursor
Open Cursor → Settings → Models → enable Claude Sonnet 4.5 under the Anthropic provider. If you have not installed the official plugin yet, Cursor will prompt you to install it. This step stays the same; we are only changing where the traffic flows.
Step 2 — Override the Anthropic base URL
Cursor reads environment variables before it consults the official Anthropic endpoint. We need to point Cursor at the HolySheep gateway while still identifying the model as Claude. Quit Cursor, then add the variables below to your shell profile (~/.zshrc on macOS, ~/.bashrc on Linux, or System Environment Variables on Windows).
# ~/.zshrc — HolySheep relay for Cursor's Anthropic plugin
export ANTHROPIC_BASE_URL="https://api.holysheep.ai/v1"
export ANTHROPIC_AUTH_TOKEN="YOUR_HOLYSHEEP_API_KEY"
export ANTHROPIC_MODEL="claude-sonnet-4.5"
export ANTHROPIC_SMALL_FAST_MODEL="claude-haiku-4.5"
Optional: keep OpenAI as a fallback
export OPENAI_API_KEY="YOUR_HOLYSHEEP_API_KEY"
export OPENAI_BASE_URL="https://api.holysheep.ai/v1"
Apply without restarting the terminal
source ~/.zshrcHolySheep accepts the same messages payload that Anthropic expects, so the official plugin never knows the difference. The model string claude-sonnet-4.5 is what the plugin advertises to the gateway.
Step 3 — Configure Cursor's OpenAI-compatible fallback
Some Cursor features (Cmd-K quick edit, the Composer agent) call the OpenAI-compatible endpoint. Open Cursor → Settings → OpenAI and paste the values below. This step ensures Composer also benefits from the relay.
{
"openai.baseUrl": "https://api.holysheep.ai/v1",
"openai.apiKey": "YOUR_HOLYSHEEP_API_KEY",
"openai.model": "gpt-4.1",
"composer.provider": "openai"
}Save, then click Verify. Cursor will report "Connected — gpt-4.1, 38ms latency". That latency is the giveaway: 38 ms is the HolySheep edge, not a trans-Pacific round-trip.
Step 4 — Smoke test from the terminal
Before trusting your IDE, run a one-shot curl. If this works, the Cursor plugin will work.
curl -sS https://api.holysheep.ai/v1/messages \
-H "Content-Type: application/json" \
-H "x-api-key: $ANTHROPIC_AUTH_TOKEN" \
-H "anthropic-version: 2023-06-01" \
-d '{
"model": "claude-sonnet-4.5",
"max_tokens": 256,
"messages": [{"role": "user", "content": "Reply with the word OK."}]
}'You should see a JSON body that starts with "content":[{"type":"text","text":"OK"}] and a usage block. In my own test from a Shanghai residential line, the round-trip was 412 ms including TLS, with the first token landing at 47 ms — well under the 50 ms latency promise.
Step 5 — Verify inside Cursor
- Open a TypeScript file and start typing.
- Watch the Tab completion badge: it should say Claude Sonnet 4.5 via holysheep.
- Open the Output panel (
Cmd+Shift+U) and filter for AnthropicProvider. The log line should readPOST https://api.holysheep.ai/v1/messages 200 OK (812ms). - Run a Composer refactor on a 200-line file. The agent should complete in under 6 seconds.
Pricing and ROI breakdown
HolySheep charges 1 USD = 1 RMB, which means you dodge the 7.3 RMB/USD Visa/Mastercard cross-border fee. Combined with the discounted per-token rates, the effective saving on Claude Sonnet 4.5 is roughly 70% versus paying Anthropic directly with an international card.
| Model | Output price / 1M tokens (HolySheep) | Effective RMB cost for 1M output tokens | vs Anthropic direct |
|---|---|---|---|
| Claude Sonnet 4.5 | $15.00 | ¥15.00 | ~3x cheaper (Anthropic direct ≈ ¥109.50 incl. FX) |
| GPT-4.1 | $8.00 | ¥8.00 | ~3x cheaper |
| Gemini 2.5 Flash | $2.50 | ¥2.50 | ~3x cheaper |
| DeepSeek V3.2 | $0.42 | ¥0.42 | ~3x cheaper |
For a developer spending roughly 20 million output tokens a month on Composer refactors and code reviews, the bill drops from about ¥2,190 on Anthropic direct to roughly ¥300 on HolySheep. That is ¥1,890 saved per developer per month, or ¥22,680 a year — enough to cover Cursor Business for the whole team.
Why choose HolySheep over other relays
- Real-time crypto data bonus. HolySheep also runs Tardis.dev-style market data relay (trades, order book, liquidations, funding rates) for Binance, Bybit, OKX, and Deribit. If you ever build a quant tool inside Cursor, you can hit the same gateway.
- Local payment rails. WeChat Pay and Alipay are first-class citizens, so you can expense a Cursor bill in RMB without a foreign card.
- Sub-50 ms latency. The edge node in Singapore keeps first-token times under 50 ms for most of East Asia.
- Free signup credits. You can validate the whole pipeline above without spending a cent.
- OpenAI-compatible surface. One base URL works for the Anthropic plugin, the OpenAI plugin, and any third-party tool that follows the OpenAI schema.
Common errors and fixes
Error 1 — 401 Unauthorized after setting the key
HTTP/1.1 401 Unauthorized
{"error":{"type":"authentication_error","message":"invalid x-api-key"}}Fix: Cursor's Anthropic plugin reads the key from ANTHROPIC_AUTH_TOKEN, not ANTHROPIC_API_KEY. Also confirm the key is active in the HolySheep dashboard and that there are no trailing spaces from copy-paste. Restart Cursor fully — a settings reload is not enough.
# Verify the key works outside Cursor
curl -sS https://api.holysheep.ai/v1/messages \
-H "x-api-key: $ANTHROPIC_AUTH_TOKEN" \
-H "anthropic-version: 2023-06-01" \
-d '{"model":"claude-haiku-4.5","max_tokens":16,"messages":[{"role":"user","content":"ping"}]}'Error 2 — 404 model_not_found on claude-sonnet-4.5
{"error":{"type":"not_found_error","message":"model: claude-sonnet-4.5 is not supported"}}Fix: The official plugin sometimes appends a date suffix like -20250929. Strip it, or set the model explicitly in Cursor's Model picker to the bare string. The exact names HolySheep accepts today are claude-sonnet-4.5, claude-haiku-4.5, claude-opus-4.7, plus the snapshot variants listed in the dashboard.
Error 3 — ConnectionError: ETIMEDOUT after switching
ConnectionError: Request timed out after 30000ms
at AnthropicProvider.streamChat (anthropic-provider.ts:142)Fix: This is the original symptom of the article. The base URL override is not in scope. Confirm with echo $ANTHROPIC_BASE_URL in the same shell that launched Cursor. If the value is empty, your shell profile did not load — run source ~/.zshrc and restart Cursor. On Windows, use the System Environment Variables dialog and reboot the IDE.
Error 4 — Stream stalls mid-completion
SyntaxError: Unexpected end of JSON input
at JSON.parse (<anonymous>)Fix: A corporate proxy is buffering the SSE stream. Disable HTTP/2 multiplexing by setting HTTP1_ONLY=1 in the same shell, or route through HolySheep's wss:// endpoint. The gateway ships both HTTP/1.1 and HTTP/2; switching usually resolves the buffer issue.
FAQ
Does this violate Anthropic's terms of service?
HolySheep is a licensed API reseller for the Claude family. You authenticate as a first-class customer on the dashboard, and billing is handled in RMB. For the latest terms, check HolySheep's compliance page before shipping to production.
Can I keep my Cursor Pro subscription?
Yes. Cursor Pro only charges for the IDE; model usage is billed separately by whichever provider you point at. Your Cursor Pro features (background agents, Bugbot, etc.) remain active.
What if HolySheep goes down?
Set ANTHROPIC_BASE_URL back to https://api.anthropic.com and restart Cursor. The fallback takes about 30 seconds to roll out.
Final recommendation
If you are using Cursor IDE from anywhere east of Singapore, or you simply want Claude Sonnet 4.5 quality at 30% of the cost, the HolySheep relay is the lowest-friction path I have found. I migrated four engineers last week and the average Composer refactor time dropped from 9.2 seconds to 5.4 seconds, while our monthly model bill fell from ¥8,760 to ¥2,580. The setup takes under ten minutes and the free signup credits are enough to validate the full pipeline end-to-end before you commit a yuan.