fix(client): cancel unused connection attempts

[ronag]

Summary

• adapt Cancel connection attempts after queued requests abort nodejs/undici#5662 to this reduced HTTP/1.1, request-only fork
• reject pre-aborted and queued requests immediately while a connector is pending
• give each connection attempt an abort signal and cancel it only when no queued request still depends on it
• ignore late connector callbacks, destroy stale sockets, and keep intentional preconnect attempts intact
• expose the attempt signal in the connector type contract

The upstream stream, pipeline, connect, upgrade, retry-interceptor, and HTTP/2 paths are not present in this fork and are intentionally excluded.

Upstream reference: nodejs#5662

Validation

Exact head: d4d6dc5259caf743c05b5e135580926e13e6a3a6 on Node.js v26.7.0

• focused connector-abort regression: 8 passed
• full unit matrix: 583 passed, 6 skipped
• full Node integration matrix: 151 passed
• TypeScript declaration tests: passed
• full npm run lint: passed
• git diff --check: passed

[Copilot]

Pull request overview

This PR adapts upstream undici behavior to cancel unused in-flight connection attempts by propagating an abort signal into connector calls and ensuring queued/pre-aborted requests are rejected promptly while a connection is still pending.

Changes:

• Adds request-driven connection-attempt cancellation via per-attempt AbortController, ignoring late connector callbacks and cleaning up stale sockets/contexts.
• Introduces an internal request-to-client abort hook (kRequestSignal) to reject pre-aborted and queued-aborted requests promptly during connecting.
• Updates connector typings/tests and adds targeted regression tests covering abort-while-connecting and shared-attempt cancellation behavior.

Reviewed changes

Copilot reviewed 7 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/types/index.test.ts	Extends type assertions to cover signal on connector options.
test/client-abort-while-connecting.js	Adds regression tests for aborting requests and cancelling unused connection attempts.
lib/dispatcher/client.js	Implements attempt-level aborting/cancellation and ignores late connector completions.
lib/core/symbols.js	Exports kRequestSignal for internal request abort wiring.
lib/core/request.js	Adds early-abort listener management/cleanup for queued requests.
lib/core/connect.js	Threads signal into the built-in connector and destroys sockets on attempt abort.
lib/api/api-request.js	Bridges API-layer abort handling into dispatcher via kRequestSignal.
index.d.ts	Exposes signal?: AbortSignal on buildConnector option contract.

Suppressed comments (1)

lib/core/connect.js:188

• signal-driven cancellation can be missed when the signal is already aborted before the abort listener is attached (not all EventTarget/AbortSignal-like implementations guarantee a late-added 'abort' listener will fire). Other parts of the codebase defensively check signal?.aborted before wiring listeners (e.g., lib/api/readable.js:331-333). Consider eagerly destroying the socket when signal.aborted is already true to ensure connection attempts are cancelled promptly in this case.

    socket
      .setNoDelay(true)
      .once(protocol === 'https:' ? 'secureConnect' : 'connect', function () {
        cleanup()

        if (callback) {
          const cb = callback
          callback = null
          cb(null, this)
        }
      })
      .on('error', function (err) {
        cleanup()

        if (callback) {
          const cb = callback
          callback = null
          cb(maybeNormalizeConnectError(err, this, { timeout, hostname, port }), null)
        }
      })

    return socket

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