Add --previous flag to find failures from recent commits

When you push a new commit, GitHub clears the previous failures.
The --previous flag searches through recent commits (2-5 commits back)
to find the most recent failures, making it easier to re-run tests
that failed before your fix.

Usage:
  bin/ci-rerun-failures           # Current commit (may be in-progress)
  bin/ci-rerun-failures --previous # Search recent commits for failures
  bin/ci-rerun-failures 1964      # Specific PR number

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

bin/ci-rerun-failures

@@ -1,7 +1,10 @@
 #!/usr/bin/env bash
 # CI Failure Re-runner
 # Automatically detects failed CI jobs and re-runs them locally
-# Usage: bin/ci-rerun-failures [pr-number]
+# Usage:
+#   bin/ci-rerun-failures          # Check current commit
+#   bin/ci-rerun-failures --previous  # Search recent commits for failures
+#   bin/ci-rerun-failures 1964     # Check specific PR
 
 set -euo pipefail
 
@@ -12,27 +15,77 @@ YELLOW='\033[1;33m'
 BLUE='\033[0;34m'
 NC='\033[0m' # No Color
 
-PR_NUMBER="${1:-}"
+# Parse arguments
+USE_PREVIOUS=false
+PR_NUMBER=""
+
+while [[ $# -gt 0 ]]; do
+  case $1 in
+    --previous|--prev|-p)
+      USE_PREVIOUS=true
+      shift
+      ;;
+    *)
+      PR_NUMBER="$1"
+      shift
+      ;;
+  esac
+done
 
 echo -e "${BLUE}=== CI Failure Re-runner ===${NC}"
 echo ""
 
-# Fetch PR status using gh CLI
+# Fetch PR info
 if [ -z "$PR_NUMBER" ]; then
-  echo "Fetching current PR status..."
-  if ! gh pr view --json statusCheckRollup >/dev/null 2>&1; then
+  if ! gh pr view --json number,commits >/dev/null 2>&1; then
     echo -e "${RED}Error: Not on a PR branch or gh CLI not authenticated${NC}"
-    echo "Usage: bin/ci-rerun-failures [pr-number]"
+    echo "Usage: bin/ci-rerun-failures [--previous] [pr-number]"
     exit 1
   fi
-  STATUS_JSON=$(gh pr view --json statusCheckRollup,number)
-  PR_NUMBER=$(echo "$STATUS_JSON" | jq -r '.number')
+  PR_INFO=$(gh pr view --json number,commits)
+  PR_NUMBER=$(echo "$PR_INFO" | jq -r '.number')
 else
-  echo "Fetching PR #$PR_NUMBER status..."
-  if ! gh pr view "$PR_NUMBER" --json statusCheckRollup >/dev/null 2>&1; then
+  if ! gh pr view "$PR_NUMBER" --json number,commits >/dev/null 2>&1; then
     echo -e "${RED}Error: PR #$PR_NUMBER not found${NC}"
     exit 1
   fi
+  PR_INFO=$(gh pr view "$PR_NUMBER" --json number,commits)
+fi
+
+# Determine which commit to check
+if [ "$USE_PREVIOUS" = true ]; then
+  # Show recent commits and let user see which had failures
+  echo -e "${BLUE}Recent commits on this PR:${NC}"
+  echo "$PR_INFO" | jq -r '.commits[-5:] | reverse | .[] | "  \(.oid[0:8]) - \(.messageHeadline)"'
+  echo ""
+
+  # Check each commit from newest to oldest for failures
+  FOUND_FAILURES=false
+  for i in 2 3 4 5; do
+    COMMIT_SHA=$(echo "$PR_INFO" | jq -r ".commits[-$i].oid // empty")
+    if [ -z "$COMMIT_SHA" ]; then
+      continue
+    fi
+
+    echo "Checking commit ${COMMIT_SHA:0:8}..."
+    CHECK_RUNS=$(gh api "repos/{owner}/{repo}/commits/$COMMIT_SHA/check-runs" --jq '.check_runs' 2>/dev/null || echo "[]")
+    FAILURE_COUNT=$(echo "$CHECK_RUNS" | jq '[.[] | select(.conclusion == "FAILURE")] | length')
+
+    if [ "$FAILURE_COUNT" -gt 0 ]; then
+      echo -e "${GREEN}Found $FAILURE_COUNT failed check(s) in commit ${COMMIT_SHA:0:8}${NC}"
+      STATUS_JSON=$(echo "$CHECK_RUNS" | jq '{statusCheckRollup: [.[] | {name: .name, conclusion: .conclusion, status: .status}], number: '$PR_NUMBER'}')
+      FOUND_FAILURES=true
+      break
+    fi
+  done
+
+  if [ "$FOUND_FAILURES" = false ]; then
+    echo -e "${YELLOW}No failures found in recent commits. Using current commit.${NC}"
+    STATUS_JSON=$(gh pr view "$PR_NUMBER" --json statusCheckRollup,number)
+  fi
+else
+  # Use current commit (HEAD of PR)
+  echo "Fetching current PR status..."
   STATUS_JSON=$(gh pr view "$PR_NUMBER" --json statusCheckRollup,number)
 fi