Detect Flaky Tests on CI Re-run and Open a Deflake Ticket

It catches the classic flaky-test signature: a CI job fails, someone hits "re-run," and the second attempt passes with no code change. The workflow compares the failed and passed runs for the same commit SHA, extracts the tests that flipped, and files a Linear ticket so the flake is tracked instead of silently re-run forever.

Use it when your team's habit is to re-run red CI until it goes green. That habit hides intermittent failures and erodes trust in the suite. This turns every "it passed the second time" into a logged, ownable task.

1. 1A GitHub `workflow_run` completed event fires when any CI run finishes.
2. 2A logic step checks whether this is a re-run (attempt > 1) that succeeded while a prior attempt for the same SHA failed.
3. 3If so, an action pulls both runs' job logs and diffs the failing test names to isolate which tests flipped red-to-green.
4. 4A logic step dedupes against open deflake tickets so repeat flakes append rather than spawn duplicates.
5. 5A Linear action creates or updates a ticket with the test names, run URLs, and commit.
6. 6A Slack message posts the new flake to the team channel.