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Retries & backoff ​

Failed attempts are retried according to a small, configurable policy. The policy is shared by the client and exported standalone as decideRetry / resolveRetryOptions.

Defaults ​

ts
{
  attempts: 3,            // max total attempts, including the first
  baseDelay: 1000,        // ms, base of the backoff series
  maxDelay: 30_000,       // ms, cap per attempt
  backoff: "exponential",
  jitter: true,           // smooth out thundering herds
  respectRetryAfter: true,// 429/503 honor the Retry-After header
}

Status table ​

StatusBehavior
408, 429, 500, 502, 503, 504retry
400, 401, 403, 404, 409, 422fail immediately
anything elsefail immediately

Customize with retryOn:

ts
const api = createClient({
  retry: {
    attempts: 5,
    retryOn: (status) => status === undefined || status >= 500, // network errors too
  },
});

retryOn fully replaces the built-in table.

Backoff ​

computeDelay({ attempts, baseDelay, maxDelay, backoff, jitter }):

  • exponential: min(baseDelay * 2^(attempts - 1), maxDelay) — with a single elementary jitter: a random factor drawn per attempt, distributed on max(baseDelay * 0.2, …) … delay.
  • fixed: constant min(baseDelay, maxDelay), also jittered when enabled.

Jittered delays cap at maxDelay. Delays shorter than 1s are floored to 0 (no artificial sleeping).

Retry-After ​

On 429 and 503, when respectRetryAfter is on and the response has a Retry-After header, the header wins and overrides the computed delay. Both HTTP-date and delta-seconds forms parse.

Lifecycle hooks ​

ts
api.on("retry", ({ key, tracker, attempts, delay, error }) => {
  console.log(`attempt ${attempts} failed; retrying in ${delay}ms`);
  expect(tracker.state).toBe("retrying");
});
api.on("success", ({ key, tracker }) => expect(tracker.state).toBe("success"));

The Tracker exposes state and the outcome is visible on success/error/cancel event payloads.

Standalone API ​

ts
import { decideRetry, resolveRetryOptions, computeDelay } from "@reqmind/core";

const options = resolveRetryOptions({ attempts: 4, baseDelay: 200 });
const decision = decideRetry({
  error,      // an HttpError, carries .status, .headers
  options,
  attempts: 2, // attempts already performed including the failed one
});
// { shouldRetry: true, delayMs: 400 }

Next: cancellation & timeouts.