Fix runner pause state overwritten by a stale list refetch

Miguel Rinconrequested to merge
fix/runner-pause-stale-list-refetch into master

What does this MR do and why?

(Hopefully) definitive fix for https://gitlab.com/gitlab-org/quality/test-failure-issues/-/work_items/44287.

The runner list queries (group and admin runner pages) use the Apollo cache-and-network fetch policy with no nextFetchPolicy, so every mutation that updates a runner also re-runs the list query over the network.

When a user pauses a runner and quickly resumes it (or the reverse), the resume-triggered refetch is absorbed into the still-in-flight pause-triggered refetch by Apollo query deduplication (on by default). That in-flight response carries a stale state before the resume. Nothing refetches after that, so the runner keeps a "Paused" badge until the page reloads. ❌

This caused a flaky test at spec/features/groups/runners/owner_manages_runners_spec.rb (and a tiny UI bug).

The fix adds context: { queryDeduplication: false } to both runner list smart queries.

It also adds documentation to teach folks how/when to use this feature.

Screenshots or screen recordings

No visual change in normal use. The bug being fixed is itself visual: a runner row that keeps a "Paused" badge after a successful resume.

How to set up and validate locally

This is hard to validate manually! It is revealed most by a flaky test, but to reproduce the bug manually in a browser, hold the list responses so the race window is easy to hit:

  1. Visit a group's runners page (Build > Runners) with at least one active runner.

  2. In the DevTools console, delay every runner list response by 2 seconds:

    const originalFetch = window.fetch;
window.fetch = async (...args) => {
  let operationName;
  try {
    operationName = JSON.parse(args[1]?.body || '{}').operationName;
  } catch {
    // not a GraphQL request
  }
  const response = await originalFetch(...args);
  if (operationName?.startsWith('getGroupRunners')) {
    await new Promise((resolve) => setTimeout(resolve, 2000));
  }
  return response;
};

  3. Click Pause on a runner, then click Resume within 2 seconds.

  4. Without this fix, the "Paused" badge comes back after ~2 seconds and stays until reload. With this fix, the badge clears and stays cleared.

References

Edited by Miguel Rincon

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