[jessealama]

The "Exit if matching branch exists" step did exit 0, which only ends that step. Since a zero exit is a success, the job simply moved on and the subsequent steps ran. When no bump/v4.x.0 branch existed, the first of them threw, and the if: failure() Zulip warning could post a misleading message about a toolchain pattern mismatch, but the real reason was the non-existence of the proper branch.

This PR drops the no-op step and guards both fetch steps on the branch check, as other later step already are. Post a dedicated warning to Zulip when no bump/v4.x.0 branch is found, and only post the toolchain warning when the toolchain fetch step itself failed.

Also replace new Exception, which is a ReferenceError in JavaScript, with new Error. Exception doesn't exist in JS. So, curiously, running this code caused a different kind of exception to be thrown (a ReferenceError for referring to something that doesn't exist), which ended up killing the step as intended, but for the wrong reason.

[kim-em]

🤖 Claude says:

Narrowing if: failure() to steps.bump_version.outcome == 'failure' silences the steps that run before it. The old blanket warning sat just above Setup for automatic PR creation, so it only ever covered what preceded it: Generate app token, Checkout code, Update the nightly-testing-YYYY-MM-DD branch, Install Zulip API client, Check last message and post if necessary, and check_branch itself. Those got a misleading toolchain message before; now they get nothing. handle_failure doesn't pick them up either, since it keys off workflow_run.conclusion, which is the triggering CI run rather than this job.

Could you add a catch-all as the last step?

    - name: Send warning message on Zulip on any other failure
      if: >-
        (failure() || cancelled())
        && steps.latest_bump_branch.outcome != 'failure'
        && steps.bump_version.outcome != 'failure'

with a generic "the bump job failed before reaching PR creation" body and a link to the run. Skipped steps are fine here, since a skipped step's outcome is skipped and both comparisons hold.

Two things I noticed while reading, neither blocking:

• Both warnings are less cause-specific than their wording suggests. latest_bump_branch can fail because listBranches errored rather than because no branch matched, and bump_version can fail fetching the branch, fetching the file, or getting empty content, all of which report "pattern doesn't match". Narrowing the if is already an improvement on what was there; exposing a reason from the scripts would finish the job.
• Pre-existing and separate: handle_failure links ${{ github.sha }}, which on a workflow_run event is the default-branch commit, not the nightly-testing head that failed. It uses github.event.workflow_run.id correctly for the run link, so github.event.workflow_run.head_sha is presumably what was intended for the commit.

[jessealama]

@kim-em I've added a catch-all as the last step, with your condition as well as a generic message and link. It'll be worth keeping our eye on the message to make sure it's useful and doesn't become recurring spam.

I also take your second point. Both scripts now record a reason output at each point of failure, and the two warnings report it now instead of asserting a single cause.

Agreed the github.sha link in handle_failure should be github.event.workflow_run.head_sha; I'll do that in a separate PR. Thanks!

[chenson2018]

I'm somewhat inclined to not touch this, as it seems we could just go ahead and remove the "CSLib Status Updates" thread completely in favor of the downstrean-lean4 reporting. Would you have any objections to this? Is there any improvements in one of your open PRs that this would end up missing?

[jessealama]

I'm happy to drop this! I've also been watching the downstream-lean4 stuff and am happy to see things get consolidated.

[jessealama]

Converting to draft while we get acquainted with the new downsteam CI setup. I'll see whether the idea contained in this PR might apply in that setting.