PR Summary

Fixes the Verify Markdown Links workflow that has been failing every Sunday since October 2025. The underlying get-changed-files action only handles pull_request and push events but the workflow also uses schedule and workflow_dispatch triggers.

Fixes #27091.

Unsupported event type: schedule. Supported types: pull_request, push

What Changed

Event Routing

The existing pull_request and push code paths are completely untouched. The new path only activates for schedule and workflow_dispatch:

flowchart LR
    A["Trigger"] --> B{"Event type?"}
    B -->|pull_request| C["PR Files API\n(paginated)"]
    B -->|push| D["Commit\ncomparison"]
    B -->|schedule| E["Trees API\n(recursive)\n✨ NEW"]
    B -->|workflow_dispatch| E
    C --> F["Filter → check links"]
    D --> F
    E --> F

For schedule/workflow_dispatch events there is no diff to compare, so the new code path uses github.rest.git.getTree with recursive: 'true' to enumerate all blobs, then feeds them through the existing filter logic. A tree.truncated warning is logged if the repository exceeds GitHub's ~100K entry API limit.

PR Context

The get-changed-files composite action has code paths for pull_request (compare via PR files API with pagination) and push (compare via commit comparison), but no path for schedule or workflow_dispatch events. These events have no PR number and no before/after commit SHAs, so neither existing branch applies.

The workflow was introduced in #26219 (October 2025) with the schedule trigger, but the action was never updated to support it.

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
• This PR is ready to merge. If this PR is a work in progress, please open this as a Draft Pull Request and mark it as Ready to Review when it is ready to merge.
• Breaking changes
  • None
• User-facing changes
  • Not Applicable
• Testing - New and feature
  • N/A or can only be tested interactively