ci(metadata): Add merge method labels and description-based auto-labeling

[tintinhamans]

This pull request updates the validate-pull-request.yml workflow to recognise labels "Squash" and "Rebase". It also detects and applies labels from the PR description.

• Added labeled and unlabeled events workflow triggers.
• Added steps to detect and apply "Squash" or "Rebase" labels based on PR description content, and to check for conflicting labels (workflow fails if both labels are present).
• Skips commit validation if the "Squash" label is present

[greptile-apps]

Greptile Summary

This PR enhances the validate-pull-request.yml workflow to support Squash and Rebase merge-method labels: it adds a description-scanning step that automatically applies the appropriate label from PR body keywords, a live label-detection step (via the GitHub API) that gates commit validation for Squash PRs, and a central result aggregation step that replaces the previous ad-hoc always() && … chain with structured infra/validation failure separation.

Key changes and observations:

• New apply-merge-labels step: Uses an ERR trap + exit 0 to guarantee the step never fails hard; label-edit failures are surfaced via autolabel-warning=true output and propagated to the PR comment as an infra warning. This design choice is intentional and documented inline.
• New labels step: Fetches labels via the GitHub API with an explicit fallback (squash=false/rebase=false/conflict=false + exit 1) on API failure, correctly propagating an infra failure through the rest of the pipeline.
• result step: Centralises failure detection logic including unexpected step skips, infra failures, and validation errors; downstream steps (post-comment, delete-stale, fail) all key off result.outputs.failed and result.outcome, giving clean single-source-of-truth semantics.
• Comment ordering corrected: The new code posts the failure comment first (post-comment step) and then deletes stale ones using IDs captured before posting, eliminating the "newly posted comment immediately deleted" race that existed in any implementation where the delete ran before the post.
• Dead env var: LABELS_OUTCOME is declared in the post-comment step's env: block but is never referenced in the run script — minor cleanup opportunity (see inline comment).
• Timeout reduction: The timeout was reduced from 3 to 2 minutes while the workflow gained two new API-calling steps (apply-merge-labels and labels). This is likely fine on ubuntu-slim but worth monitoring on busy queues.

Confidence Score: 3/5

• The core logic is sound and well-defended, but the PR has accumulated many edge-case interactions (infra-failure propagation, cancellation windows, stale-comment cleanup races) that have been flagged and partly addressed across a long review thread — careful regression testing on the full event matrix is advisable before merging.
• The structural design (ERR-trap guaranteeing exit 0 on apply-merge-labels, explicit API fallback on labels, result aggregation keyed off by all downstream steps) is solid and the ordering fix (post before delete) resolves a real prior bug. However, the number of outstanding edge-case concerns raised in previous threads — label-conflict infra message conflation, stale-comment deletion under skipped result, unexpected skip detection gaps, timeout reduction with added API calls — leaves meaningful residual risk. The one new finding (unused LABELS_OUTCOME env var) is minor.
• .github/workflows/validate-pull-request.yml — specifically the result step (lines 315–389) and post-comment / delete-stale interaction (lines 391–487) deserve the most scrutiny given the complexity of their combined conditional logic.

Important Files Changed

Filename	Overview
.github/workflows/validate-pull-request.yml	Significant rework adding description-based auto-labeling, per-label merge method detection (Squash/Rebase), and a central result-aggregation step; overall logic is sound but contains a dead LABELS_OUTCOME env var in the post-comment step and has several edge-case interactions documented across previous review threads.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[PR Event\nopened/edited/synchronize/reopened/labeled/unlabeled] --> B[apply-merge-labels]
    B -->|labeled/unlabeled event| C[Skip – manual label event]
    B -->|synchronize + label already present| D[Skip – respect manual override]
    B -->|Description matches squash/rebase pattern| E[gh pr edit: add/swap label]
    B -->|No matching pattern| F[No label change]
    C & D & E & F --> G[Detect merge method labels\nvia GitHub API]
    G -->|API failure| H[squash=false, rebase=false, conflict=false\nexit 1 → INFRA_FAILED]
    G -->|Both Squash + Rebase| I[conflict=true\nexit 1 → validation failure]
    G -->|Squash only| J[squash=true]
    G -->|Rebase or no label| K[squash=false]
    J & K --> L[Checkout base branch]
    I & H --> L
    L --> M[Fetch PR head\nSkipped if squash=true or conflict]
    L --> N[Load valid tags]
    N --> O[Validate PR title\nAlways runs when tags loaded]
    M --> P[Validate PR commits\nSkipped if squash=true, conflict, or labels failed]
    O & P --> Q[Determine validation result\naggregates infra + validation failures]
    Q -->|failed=true| R[Post failure comment]
    Q -->|failed=false| S[Skip comment]
    R --> T[Delete stale bot comments\nusing OLD_COMMENT_IDS captured before posting]
    S --> T
    T --> U{failed?}
    U -->|true| V[exit 1 – job fails]
    U -->|false| W[Job passes]

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Prompt To Fix All With AI

This is a comment left during a code review.
Path: .github/workflows/validate-pull-request.yml
Line: 405

Comment:
**Unused `LABELS_OUTCOME` env var**

`LABELS_OUTCOME` is declared in the step's `env:` block but is never referenced anywhere inside the `run:` script (lines 408–463). The post-comment body is constructed using `IS_CONFLICT`, `IS_SQUASH`, `IS_REBASE`, `INFRA_FAILED`, and `AUTOLABEL_WARNING` — `LABELS_OUTCOME` contributes nothing. Removing it avoids confusion for future maintainers who might assume it drives some conditional logic.

```suggestion
          AUTOLABEL_WARNING: ${{ steps.apply-merge-labels.outputs.autolabel-warning }}
          VALID_TAGS: ${{ steps.load-tags.outputs.valid-tags }}
          IS_SQUASH: ${{ steps.labels.outputs.squash }}
          IS_REBASE: ${{ steps.labels.outputs.rebase }}
          IS_CONFLICT: ${{ steps.labels.outputs.conflict }}
          INFRA_FAILED: ${{ steps.result.outputs.infra_failed }}
          RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
```

How can I resolve this? If you propose a fix, please make it concise.

_{Last reviewed commit: f12a758}

[xezon]

Can you also add a way to disable conventional commit tags check for the commits? For example by placing a keyword into the Pull description. Then only check it on the Pull Request title.

[Mauller]

Can you also add a way to disable conventional commit tags check for the commits? For example by placing a keyword into the Pull description. Then only check it on the Pull Request title.

Maybe check to see if the PR description contains "merge by rebase"

[xezon]

The described functionality looks good to me. Does it work?

[tintinhamans]

The described functionality looks good to me. Does it work?

I have merged this to main on my fork https://github.com/tintinhamans/GeneralsGameCode, feel free to submit a test PR there to test.

[xezon]

Can you test it? I trust you if you say it works.

[Mauller]

Had to unsubscribe to this, it was blowing up my phone too much, munkee needs his sleep! lol