ci: fix release pipeline race condition in PR lookup after squash merge

[Copilot]

Fix release pipeline race condition: add retry logic and commit-message fallback for PR lookup after squash merges.

Problem

PR #3's squash merge triggered the release workflow within 3 seconds. The gh api commits/{sha}/pulls call returned empty — GitHub hadn't indexed the commit→PR association yet. This set bump_type=none, skipping all release steps (version bump, changelog, GitHub Release creation).

Fix

Three resilience mechanisms added to the "Determine version bump" step:

• Retry with backoff — commits/pulls API retries 3× with increasing delay (5s, 10s), skipping the sleep after the final attempt
• Commit-message fallback — if retries exhaust, extracts PR number from the squash-merge commit subject (Title (#N), using the last match to avoid picking up issue references) and looks up the PR directly by number
• API error surfacing — gh api errors are now captured and logged as ::warning:: annotations (retryable calls) or ::error:: with immediate job failure (direct PR lookup), instead of being silently swallowed via 2>/dev/null || echo ""

# Retry with error surfacing
GH_ERR_FILE="$RUNNER_TEMP/gh_api_err_$$"
PR_DATA=$(gh api "repos/.../commits/$SHA/pulls" \
  --jq '.[0] // empty' 2>"$GH_ERR_FILE") || API_ERR=$(cat "$GH_ERR_FILE")

# Fallback: extract PR number from squash-merge commit message "(#N)"
if [ -z "$PR_DATA" ]; then
  PR_NUMBER=$(git log -1 --format=%s "$COMMIT_SHA" | grep -oE '\(#[0-9]+\)' | tail -1 | tr -d '(#)')
  if [ -n "$PR_NUMBER" ]; then
    PR_DATA=$(gh api "repos/.../pulls/$PR_NUMBER" 2>"$GH_ERR_FILE") || API_ERR=$(cat "$GH_ERR_FILE")
    if [ -n "$API_ERR" ]; then
      echo "::error::Failed to fetch PR #$PR_NUMBER: $API_ERR"
      exit 1
    fi
  fi
fi

Type of Change

• Major – Breaking change (requires a new major version bump)
• Minor – New feature, backward-compatible (requires a new minor version bump)
• Patch – Bug fix or internal improvement, backward-compatible (requires a new patch version bump)

Next steps

Merging this PR serves as the initial release trigger — the fixed pipeline will bump 1.0.0 → 1.0.1 and create the first GitHub Release. Edit the checkbox above to Minor before merge if v1.1.0 is preferred.

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[Copilot]

Pull request overview

This PR improves the GitHub Actions release workflow’s ability to reliably find the merged PR associated with a push to main, addressing GitHub’s delayed commit→PR indexing after squash merges so releases aren’t skipped.

Changes:

• Add retry logic with increasing delays for the commits/{sha}/pulls PR lookup.
• Add a commit-subject fallback that extracts (#N) and fetches the PR directly when the commits/pulls lookup remains empty.