Fix: wait-for-workflow should fail immediately when workflow does not exist

[Copilot]

The wait-for-workflow action did not fail immediately when given a non-existent workflow. The listWorkflowRuns GitHub API returns 200 with an empty array for unknown workflow filenames, so the action would silently poll until timeout instead of erroring fast.

Changes

• actions/wait-for-workflow/action.yml: Adds a getWorkflow pre-flight call before the polling loop. This endpoint returns 404 reliably for non-existent workflows, allowing the action to call core.setFailed() and return immediately rather than exhausting the timeout. Also changes the default value of fail-on-timeout from false to true.
• .github/workflows/_test-wait-for-workflow-action.yml: Adds a test workflow that:
  • Triggers only on pull_request for paths actions/wait-for-workflow/** and .github/workflows/_lint.yml
  • Uses actions/checkout@v6
  • Verifies the action fails when given a non-existent workflow ID
  • Verifies the action works correctly for an existing workflow (_lint.yml) using default timeout and polling interval, failing on timeout

Checklist

• I have added or updated appropriate labels to this PR
• I have tested my changes
• I have updated the documentation if needed

Original prompt

The wait for workflow action should always fail if the workflow does not exist

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[FidelusAleksander]

@copilot Few things

For the test workflow:

1. Make sure you use all the latest action versions (e.g actions/checkout@v6)
2. Trigger only on pull request, remove the push trigger
3. Test an existing workflow as well - use the _lint.yml workflow

[Copilot]

@copilot Few things

For the test workflow:...

Done in 75d7bd2:

1. Updated to actions/checkout@v6
2. Removed the push trigger — now only runs on pull_request
3. Added a test-existing-workflow job that uses _lint.yml to verify the action doesn't fail for a workflow that exists

[FidelusAleksander]

@copilot In the test workflow for existing workflow (lint) you should fail on timeout, and use the default timeout duration/interval

Also let's change the default setting of fail-on-timeout to true

[Copilot]

Pull request overview

This PR updates the wait-for-workflow composite action to fail fast when given a workflow filename/ID that doesn’t exist, avoiding silent polling until timeout caused by listWorkflowRuns returning 200 with an empty result for unknown workflow filenames.

Changes:

• Added a pre-flight actions.getWorkflow call in wait-for-workflow to reliably detect non-existent workflows (404) before entering the polling loop.
• Added a PR-only workflow to exercise both the non-existent-workflow failure case and an existing-workflow non-failure smoke case.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
actions/wait-for-workflow/action.yml	Adds a getWorkflow pre-check to error immediately on unknown workflows.
.github/workflows/_test-wait-for-workflow-action.yml	Adds a CI workflow to validate the new fail-fast behavior and a basic existing-workflow path.

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