workers-ai-provider: Workers AI rate-limit error 3021 is classified as non-retryable

[scott-edwards]

Workers AI binding error 3021 is treated as non-retryable despite HTTP 429

workers-ai-provider@4.0.0 does not recognize Workers AI inference RPM-limit code 3021. The native binding throws Error("3021: rate limiting: inference request per min rate reached"). normalizeBindingError constructs an APICallError without statusCode, with isRetryable: false, so native AI SDK retries stop immediately.

The corresponding stored Workers AI Gateway response was HTTP 429 with httpCode: 429, internalCode: 3021, name: "AiError", and the same description. No customer identifiers or private prompts are included here.

Reproduction

import { createWorkersAI } from "workers-ai-provider";

const model = createWorkersAI({
  binding: {
    run: async () => {
      throw new Error("3021: rate limiting: inference request per min rate reached");
    },
  },
})("@cf/zai-org/glm-5.3-flash");

try {
  await model.doStream({
    prompt: [{ role: "user", content: [{ type: "text", text: "Welcome" }] }],
  });
} catch (error) {
  console.log(error.statusCode, error.isRetryable);
  // Actual: undefined, false. Expected: 429, true.
}

Proposed correction

Add 3021: 429 to WORKERS_AI_ERROR_CODE_TO_STATUS in packages/gateway-core/src/workers-ai-errors.ts. This also lets the existing parser recognize the error code. No custom retry loop is required.

Validation

An isolated copy of the released package fails four rate-limit tests before the correction and passes all seven tests after it:

• Streaming and non-streaming binding errors retain their cause and map to retryable HTTP 429.
• Native AI SDK streamText and generateText each recover after two simulated 3021 errors, using the SDK's existing increasing delays (approximately 2 and 4 seconds).
• Invalid input, unknown errors, and cancellation do not retry.

This is controlled local validation, not a production load test. The numeric model/account RPM limit is not established by this report.