Feature/add cancellation support

[lewinpauli]

As needed since 6 years here is cancellation support #181

• Add CancellationToken class for operation cancellation
• Add CancelledException for cancelled operations
• Integrate cancellation into BaseOptions, QueryOptions, MutationOptions
• Implement cancellation handling in QueryManager
• Add queryCancellable() and mutateCancellable() convenience methods
• Add comprehensive test suite (7 tests)
• Add usage documentation

-> no breaking changes

-> all tests pass

[jorg1piano]

can't really see how it cancels the underlying request? can you explain?

[lewinpauli]

you are right i haven't noticed that the underlying http request wasn't actually cancelled, only the subscription was cancelled.

I now added true HTTP request cancellation to the graphql package.

• Created custom HttpLink with platform-specific cancellation support

• Web: Uses XMLHttpRequest.abort() → shows "(canceled)" in Chrome DevTools

• IO (Linux/Desktop/Mobile): Uses HttpClient.close(force: true) + request.abort() → terminates TCP connection

• Added CancellationContextEntry to pass the token through the Link chain

• Added web package dependency (replaces deprecated dart:html)

• Added additional tests for http cancellation

Result:

operation.cancel() now actually aborts the underlying HTTP request

Not just ignoring the response — the network connection is terminated

I verified it, in chrome and linux the http request gets actually cancelled

[jorg1piano]

You should run dart format --line-length=80 ./

There is quite a lot of irrelevant white space noise in this PR

[vincenzopalazzo]

Hi thanks for the contrinbution, this PR is not getting any review because I was not pinged by my internal review bot due that commits are not following the contribution guidelines. I suggest you add it to the claude.md or any other agent.md file because following the commit style is what get any PR merged in a couple of hours or delayed months.

Sorry

for commit style see https://github.com/zino-hofmann/graphql-flutter/blob/main/docs/dev/MAINTAINERS.md#commit-style

[jorg1piano]

I'm very skeptical of this approach.

It does not seem to consider how this would work with observables. It also does not really play well with the cache; any cancellation that does not know about the link and the cache will not work in a nice way when you throw streams into the mix.

It also makes me very skeptical because, when I looked at the original PR, it did not actually do what it claimed it did, which makes me think "AI slop" right away.