chore: T8937: retire check-pr-conflict.yml reusable (eps1lon conflict labeler)

[andamasov]

Deletes the eps1lon-based check-pr-conflict.yml reusable — the last deferred follow-up of the T8937 Mergify-replaceable GHA retirement. It was preserved in vyos/.github#146 pending its sole consumer's migration.

Why it's now safe

The only consumer, vyos/vyos-documentation, migrated to Mergify in vyos/vyos-documentation#2103 (merged): conflict labeling is the inherited central Label conflicting pull requests rule + a new local Comment on conflicting pull requests rule. The reusable has no remaining live consumer — verified via the authoritative git-tree API: rolling clean, sagitta clean.

Preserved (NOT this PR)

• check-pr-merge-conflict.yml — the T8934 committed-conflict-marker case (scans file content for <<<<<<<; Mergify's conflict predicate only sees mergeable_state, not committed text). Untouched.

Remaining reference (exempt)

vyos/vyos-documentation@current (1c compat alias — write-protected, frozen since 2026-05-30, scheduled for 1c-Task-7 deletion) still pins @production. No auto-trigger (frozen, no pushes); clears on the alias deletion. Same disposition as the EXEMPT-1C-COMPAT-ALIAS stragglers in the main retirement. vyos/vyos-documentation@circinus references a different (check-open-prs-conflict.yml@current) already-broken reusable — pre-existing, unrelated to this file.

Advances: T8937

🤖 Generated by robots

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository YAML (base), Central YAML (inherited), Organization UI (inherited)

Review profile: CHILL

Plan: Pro

Run ID: 39afb43a-23ba-4e04-a162-fef630d51ba1

📥 Commits

Reviewing files that changed from the base of the PR and between b9d5d38 and d36f317.

📒 Files selected for processing (2)

• .github/workflows/check-pr-conflict.yml
• AGENTS.md

🔗 Linked repositories identified

CodeRabbit considers these linked repositories for cross-repo context during reviews:

• ansible/ansible (manual)

💤 Files with no reviewable changes (1)

• .github/workflows/check-pr-conflict.yml

✅ Files skipped from review due to trivial changes (1)

• AGENTS.md

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📝 Walkthrough

Summary by CodeRabbit

• Chores
  • Removed the automated pull-request merge-conflict checking workflow; merge conflict detection is no longer run automatically during PR review.
  • Updated documentation to reflect the workflow retirement and clarify that the retained merge-conflict check covers committed-conflict-marker scenarios.

Walkthrough

Removes the .github/workflows/check-pr-conflict.yml workflow and updates AGENTS.md to list check-pr-merge-conflict (notes it covers committed-conflict-marker/T8934). No code exports changed.

Changes

Workflow retirement and docs update

Layer / File(s)	Summary
Workflow file deletion .github/workflows/check-pr-conflict.yml	Removed the check-pr-conflict.yml workflow (28 lines deleted). Previously used bullfrogsec/bullfrog@v0.8.4 and eps1lon/actions-label-merge-conflict@v3.
Docs update AGENTS.md	Reworded repository workflow listing: replaced check-pr-conflict with check-pr-merge-conflict and added clarifying text about coverage of committed-conflict-marker (change at AGENTS.md line 29).

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	Title clearly summarizes the primary change: removal of the check-pr-conflict.yml workflow file as part of T8937 retirement.
Description check	✅ Passed	Description is directly related to the changeset, explaining the rationale for removing check-pr-conflict.yml, its replacement by Mergify, and verification of no remaining consumers.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch chore/T8937-retire-check-pr-conflict

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_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[andamasov]

Adversarial review — b9d5d38 (+ doc-fix d36f317) — Codex + Gemini parallel

Gemini: APPROVE, NO FINDINGS. Codex: REQUEST CHANGES (1 low) → fixed.

Both confirmed the load-bearing checks:

• Correct file deleted: check-pr-conflict.yml (eps1lon) removed; check-pr-merge-conflict.yml (T8934 committed-marker case) preserved/untouched — verified by both.
• No live consumer 404: the only remaining reference is vyos/vyos-documentation@current (frozen 1c compat alias, write-protected, scheduled for deletion) — both judged the exemption sound.

1. [low][single-source: Codex] AGENTS.md:29 — repo-layout list still named check-pr-conflict after deletion → fixed in d36f317 (removed from the list; check-pr-merge-conflict kept with a note on why it's preserved). The script check-pr-conflicts.py and check-pr-merge-conflict.yml references elsewhere are different artifacts, correctly retained.

Doc-only fix commit d36f317 is covered by this review (no workflow-file delta beyond the reviewed deletion).

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Codex finding fixed; Gemini APPROVE. See /audit-pr-threads for resolution mechanics.