ci: add reusable workflow to comment on first-time PRs #6

Workflow file for this run

.github/workflows/merge-conflict-detector.yml at 7432657

	name: Merge Conflict Detector

	on:
	workflow_call:

	pull_request_target:
	types: [opened, reopened, synchronize, ready_for_review]
	push:
	branches: [main, develop]


	jobs:

	detect-merge-conflicts:
	name: Check Open PRs for Conflicts
	runs-on: ubuntu-latest

	steps:
	- name: Checkout repository
	uses: actions/checkout@v4
	with:
	fetch-depth: 0

	- name: Get open PRs targeting this branch
	id: get-prs
	env:
	GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
	run: \|
	echo "[FETCH] ========================================"
	echo "[FETCH] Fetching open PRs targeting: ${{ github.ref_name }}"

	gh pr list \
	--base "${{ github.ref_name }}" \
	--state open \
	--json number \
	--jq '.[].number' > pr_numbers.txt

	PR_COUNT=$(wc -l < pr_numbers.txt \| tr -d ' ')
	echo "[FETCH] Found ${PR_COUNT} open PR(s)"

	if [ "${PR_COUNT}" -eq 0 ]; then
	echo "[FETCH] No open PRs to check"
	echo "has_prs=false" >> $GITHUB_OUTPUT
	else
	echo "has_prs=true" >> $GITHUB_OUTPUT
	echo "[FETCH] PRs to check:"
	cat pr_numbers.txt \| while read pr; do
	echo "[FETCH] - PR #${pr}"
	done
	fi
	echo "[FETCH] ========================================"

	- name: Check single PR for merge conflicts
	if: github.event_name == 'pull_request_target'
	env:
	GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
	run: \|
	set -euo pipefail

	echo "[CHECK] ========================================"
	echo "[CHECK] Checking PR #${{ github.event.pull_request.number }}"

	BASE_REF="${{ github.event.pull_request.base.ref }}"
	PR_NUMBER="${{ github.event.pull_request.number }}"

	echo "[CHECK] Fetching latest base branch: ${BASE_REF}"
	git fetch origin "${BASE_REF}"

	BASE_SHA=$(git rev-parse "origin/${BASE_REF}")
	echo "[CHECK] Latest base SHA: ${BASE_SHA}"

	PR_DATA=$(gh pr view "$PR_NUMBER" --json headRefName,headRefOid,title)

	PR_HEAD_REF=$(echo "$PR_DATA" \| jq -r '.headRefName')
	PR_HEAD_SHA=$(echo "$PR_DATA" \| jq -r '.headRefOid')
	PR_TITLE=$(echo "$PR_DATA" \| jq -r '.title')

	echo "[CHECK] Latest PR head: ${PR_HEAD_REF} @ ${PR_HEAD_SHA}"

	# Fetch PR commit directly (works for forks)
	git fetch origin "${PR_HEAD_SHA}"

	echo "[CHECK] Fetching changed files in PR"
	gh pr view "$PR_NUMBER" --json files --jq '.files[].path' > pr_files.txt

	FILE_COUNT=$(wc -l < pr_files.txt \| tr -d ' ')
	echo "[CHECK] Total files changed: ${FILE_COUNT}"

	if [ "$FILE_COUNT" -eq 0 ]; then
	echo "[CHECK] No files changed — exiting successfully"
	exit 0
	fi

	echo "[CHECK] Changed files:"
	sed 's/^/[CHECK] - /' pr_files.txt

	echo "[CHECK] Running merge-tree conflict analysis"

	set +e
	MERGE_OUTPUT=$(git merge-tree "$BASE_SHA" "$PR_HEAD_SHA" 2>&1)
	MERGE_EXIT_CODE=$?
	set -e

	echo "[RESULT] ========================================"
	echo "[RESULT] CONFLICT DETECTION SUMMARY"
	echo "[RESULT] ========================================"
	printf "[RESULT] PR #%s: %s\n" "$PR_NUMBER" "$PR_TITLE"
	echo "[RESULT] Base: ${BASE_REF} @ ${BASE_SHA}"
	echo "[RESULT] Head: ${PR_HEAD_REF} @ ${PR_HEAD_SHA}"
	echo "[RESULT] ----------------------------------------"
	echo "[RESULT] Total files changed: ${FILE_COUNT}"
	echo "[RESULT] ========================================"

	# Check for conflicts in merge-tree output
	if echo "$MERGE_OUTPUT" \| grep -q "CONFLICT"; then
	echo "[RESULT] ❌ STATUS: FAILED"
	echo "[RESULT] Merge conflicts detected with latest base branch"
	echo "$MERGE_OUTPUT" \| grep "CONFLICT" \| sed 's/^/[RESULT] /'
	exit 1
	elif [ "$MERGE_EXIT_CODE" -ne 0 ]; then
	echo "[RESULT] ⚠️ WARNING: Merge-tree exited with code ${MERGE_EXIT_CODE}"
	echo "[RESULT] This may indicate a conflict or error"
	exit 1
	else
	echo "[RESULT] ✅ STATUS: PASSED"
	echo "[RESULT] No merge conflicts detected"
	exit 0
	fi

	- name: Check all open PRs for conflicts
	if: steps.get-prs.outputs.has_prs == 'true' && github.event_name == 'push'
	env:
	GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
	run: \|
	set -euo pipefail
	echo "[CHECK-ALL] ========================================"
	echo "[CHECK-ALL] Checking all open PRs after merge to ${{ github.ref_name }}"

	FAILED=false
	CONFLICT_SUMMARY=""

	while IFS= read -r pr_number; do
	echo "[CHECK-ALL] ----------------------------------------"
	echo "[CHECK-ALL] Checking PR #${pr_number}"

	PR_DATA=$(gh pr view ${pr_number} --json headRefName,headRefOid,baseRefName,title)
	PR_HEAD_REF=$(echo "$PR_DATA" \| jq -r '.headRefName')
	PR_HEAD_SHA=$(echo "$PR_DATA" \| jq -r '.headRefOid')
	PR_BASE_REF=$(echo "$PR_DATA" \| jq -r '.baseRefName')
	PR_TITLE=$(echo "$PR_DATA" \| jq -r '.title')

	echo "[CHECK-ALL] PR #${pr_number}: ${PR_TITLE}"
	echo "[CHECK-ALL] Base: ${PR_BASE_REF}"
	echo "[CHECK-ALL] Head: ${PR_HEAD_REF} @ ${PR_HEAD_SHA}"

	echo "[CHECK-ALL] Fetching latest branches..."
	git fetch origin ${PR_BASE_REF} >/dev/null 2>&1

	# Fetch the PR head commit directly (works for forks)
	git fetch origin ${PR_HEAD_SHA} >/dev/null 2>&1

	# Get latest base SHA
	LATEST_BASE_SHA=$(git rev-parse origin/${PR_BASE_REF})
	echo "[CHECK-ALL] Latest base SHA: ${LATEST_BASE_SHA}"
	echo "[CHECK-ALL] PR head SHA: ${PR_HEAD_SHA}"

	# Use git merge-tree to check for conflicts
	echo "[CHECK-ALL] Running merge simulation..."
	set +e
	MERGE_OUTPUT=$(git merge-tree ${LATEST_BASE_SHA} ${PR_HEAD_SHA} 2>&1)
	MERGE_EXIT_CODE=$?
	set -e

	CHECK_NAME="Merge Conflict Detector"
	HAS_CONFLICT=false

	# Check for "CONFLICT" in the output (most reliable indicator)
	if echo "$MERGE_OUTPUT" \| grep -q "CONFLICT"; then
	HAS_CONFLICT=true
	echo "[CHECK-ALL] ❌ Conflict detected via merge-tree output"
	echo "$MERGE_OUTPUT" \| grep "CONFLICT" \| sed 's/^/[CHECK-ALL] /'
	# Exit code 1 from merge-tree also indicates conflicts
	elif [ "$MERGE_EXIT_CODE" -eq 1 ]; then
	HAS_CONFLICT=true
	echo "[CHECK-ALL] ❌ Conflict detected via merge-tree exit code"
	else
	echo "[CHECK-ALL] ✅ No conflicts detected"
	fi

	# Post check run status (suppress JSON output)
	if [ "$HAS_CONFLICT" = true ]; then
	echo "[CHECK-ALL] ❌ Posting failure status for PR #${pr_number}"

	gh api repos/${{ github.repository }}/check-runs \
	-X POST \
	-f name="${CHECK_NAME}" \
	-f head_sha="${PR_HEAD_SHA}" \
	-f status="completed" \
	-f conclusion="failure" \
	-f "output[title]=Merge conflicts detected" \
	-f "output[summary]=This PR has merge conflicts with ${PR_BASE_REF}. Please update your branch." \
	--silent

	FAILED=true
	CONFLICT_SUMMARY="${CONFLICT_SUMMARY}
	PR #${pr_number}: ${PR_TITLE}"
	else
	echo "[CHECK-ALL] ✅ Posting success status for PR #${pr_number}"

	gh api repos/${{ github.repository }}/check-runs \
	-X POST \
	-f name="${CHECK_NAME}" \
	-f head_sha="${PR_HEAD_SHA}" \
	-f status="completed" \
	-f conclusion="success" \
	-f "output[title]=No merge conflicts" \
	-f "output[summary]=This PR cleanly merges into ${PR_BASE_REF}" \
	--silent
	fi

	done < pr_numbers.txt

	echo "[CHECK-ALL] ========================================"
	if [ "$FAILED" = true ]; then
	echo "[CHECK-ALL] ⚠️ CONFLICTS DETECTED"
	echo "[CHECK-ALL] The following PRs have merge conflicts:"
	echo "${CONFLICT_SUMMARY}"
	echo "[CHECK-ALL] ========================================"
	echo "[CHECK-ALL] Check runs have been posted to each PR"
	echo "[CHECK-ALL] ========================================"
	exit 0
	else
	echo "[CHECK-ALL] ✅ ALL PRs CLEAN"
	echo "[CHECK-ALL] All open PRs merge cleanly into ${{ github.ref_name }}"
	echo "[CHECK-ALL] ========================================"
	exit 0
	fi

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ci: add reusable workflow to comment on first-time PRs #6

Workflow file

ci: add reusable workflow to comment on first-time PRs #6

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Workflow file for this run