test: smoke-test proxy IT dispatch workflow (DO NOT MERGE)

[vikrantpuppala]

Purpose

End-to-end smoke test of the IT dispatch workflow added in #799. Not for merge — closing after the smoke test confirms the workflow behaves correctly.

Diff

A 5-line docstring addition in `src/databricks/sql/backend/kernel/init.py` — touches `src/` so the changed-paths filter in `trigger-tests-pr` fires.

Expected behaviour to verify

Phase 1 — PR opened (this commit)

• `skip-integration-tests-pr` runs and posts a synthetic `success` `Python Proxy Tests` check.
• `trigger-tests-pr` and `merge-queue-python` skip (no label, no merge_group).
• Verify `Python Proxy Tests` shows up as green in the check rollup.

Phase 2 — apply `integration-test` label

• `trigger-tests-pr` runs.
  • `Detect changed driver paths` → `python: true` (we touched `src/`).
  • `Sanitize PR title` → strips quote/newline/etc. from the title.
  • `Dispatch Python tests to internal repo` → either succeeds (if secrets are installed on the App + this repo) or fails with a 403/401 (if secrets aren't installed yet → expected, will be addressed separately).
• If dispatch succeeds: comment posted on PR; driver-test repo's `python-proxy-tests.yml` workflow runs against this branch's HEAD.
• If dispatch fails: `Fail check on dispatch error` step posts a `failure` check on `Python Proxy Tests` so we know the gate didn't silently pass.

Phase 3 — push a new commit

• `remove-label-on-new-commit` runs.
  • Removes the `integration-test` label.
  • Posts the "Integration test approval reset" comment.

Phase 4 — cleanup

• Close PR. No merge.

Out of scope

This PR doesn't verify the merge queue path (`merge-queue-python` job). That requires merge queue to be enabled on `main` branch protection (operational step, separate from this PR).

This pull request and its description were AI-assisted by Isaac.

[github-actions]

Integration test approval reset.

New commits were pushed to this PR. The integration-test label has been automatically removed for security.

A maintainer must re-review the changes and re-add the label to trigger tests again.

Latest commit: 9ed6916

[vikrantpuppala]

Smoke-test results

End-to-end exercise of the IT dispatch workflow added in #799. Results:

What worked ✅

• Phase 1 — PR opened
  • `skip-integration-tests-pr` ran and posted a synthetic `Python Proxy Tests: success` check.
  • `trigger-tests-pr` + `merge-queue-python` correctly skipped (no label, no merge_group).
• Phase 3 — push new commit (synchronize event)
  • `remove-label-on-new-commit` ran, removed the `integration-test` label, and posted the "Integration test approval reset" comment.
  • `skip-integration-tests-pr` re-ran on the new SHA and posted a fresh synthetic-success.
  • Verified: `gh pr view --json labels` returned empty; comment shows up in PR timeline from `github-actions[bot]`.

What broke (expected, secrets not installed) ⚠️

• Phase 2 — label applied, dispatch attempted
  • `trigger-tests-pr` ran but failed at "Generate GitHub App Token (internal repo)" because `INTEGRATION_TEST_APP_ID` / `INTEGRATION_TEST_PRIVATE_KEY` aren't installed on this repo yet.

Real bug found 🐛

While we expected dispatch to fail without the secrets, the failure handler (`Fail check on dispatch error`) also failed with `Input required and not supplied: github-token`. Reason: my failure step uses the App-token-generated public-repo token (`steps.public-token.outputs.token`), but `public-token` itself depends on the same App secrets that are missing. When the secrets are absent the failure handler can't post a check-run, so the gate just stays green from Phase 1's stale synthetic success — exactly the silent-pass anti-pattern we're trying to avoid.

Note this is the same shape as the canonical `adbc-drivers/databricks` workflow, so it's a latent issue there too. Fix is to fall back to `${{ github.token }}` (the default workflow token, which has `checks: write` because we already declared that permission) in the failure handler.

Follow-ups

1. Fix the failure handler in `trigger-integration-tests.yml` — change the `Fail check on dispatch error` step to use `${{ github.token }}` instead of `steps.public-token.outputs.token`. Will open a follow-up PR.
2. Install the App secrets (`INTEGRATION_TEST_APP_ID` / `INTEGRATION_TEST_PRIVATE_KEY`) on this repo + add `databricks-sql-python` to the App's installation. Operational task — already documented in ci: add label-gated proxy-test dispatch to databricks-driver-test #799's description.
3. Enable merge queue + mark `Python Proxy Tests` required on `main` branch protection. After [Cleanup] Move connector files to root #2.