Fork PRs were failing the Chango / Create chango Fragment job because the action attempted to push to contributor forks, which is not permitted with repository credentials. This change gates auto-push to same-repo branches and documents the manual fragment command for fork contributors.

• Workflow behavior

  • Updated .github/workflows/chango.yml to disable commit-and-push when the PR head repo differs from the base repo.
  • Keeps automatic chango fragment commits for in-repo branches while preventing 403 push failures on forks.

• Contributor guidance

  • Updated .github/CONTRIBUTING.rst with explicit fork-PR guidance and the command to create a chango fragment manually.

commit-and-push: ${{ steps.check_title.outputs.COMMIT_AND_PUSH == 'true' && github.event.pull_request.head.repo.full_name == github.repository }}

uv run chango new --slug pr-1234-fix-telegram-api-error