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10. Redirect · Retry · Cookie

These three features aren't provided by undici's request, so they're implemented directly in the wrapper.

Redirect

Enabled with followRedirects(max). undici is kept at maxRedirections: 0, and the wrapper repeats the redirect handling.

  • Tracked statuses: 301, 302, 303, 307, 308 + Location header.
  • Method rewrite: 303, or 301/302 + POST, is rewritten to GET with the body removed.
  • Authorization preservation rule: Authorization is preserved on a same-origin redirect (identical scheme+host+port) and removed cross-origin.
  • Exceeding the max count fails with requestFailed.
  • Supported locations: absolute (http(s)://...) and path-absolute (/...).

Retry

retry(attempts) retries transport failures (exponential backoff + full jitter interval — default 50ms, doubling per attempt, capped at 1 second, randomized between 0 and the cap).

  • Retried target: retriable transport failures (connection errors, timeout, etc.). Status codes (4xx/5xx) themselves are not retried.
  • Streaming (a download sink or upload provider) can't be rewound, so it's excluded from retry.

Enabled with cookies(). Since fetch/undici has no server-side persistent cookie jar, the wrapper owns its own jar. It follows narrow semantics:

  • Stored by exact host match (the Domain attribute is not supported).
  • Default Path=/. Only the Path/Secure/Max-Age attributes are interpreted; Domain/Expires are ignored.
  • Deleted if Max-Age<=0.
  • A secure cookie is sent only on a secure (https) request.
  • Up to 128 per host; oldest removed first once exceeded.

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