fix: implementation for #1524

Comprehensive duplicate PR prevention system:

1. Pre-flight check scripts:
   - scripts/check-existing-prs.sh (Bash)
   - scripts/check_existing_prs.py (Python)
   - scripts/pr-safe.sh (user-friendly wrapper)

2. Documentation:
   - docs/duplicate-pr-prevention.md

Prevents duplicate PRs by checking for existing PRs before
creating new ones. Exit codes:
- 0: Safe to create PR
- 1: Existing PRs found (stop)
- 2: Error

Closes #1524

docs/duplicate-pr-prevention.md

@@ -0,0 +1,143 @@
+# Duplicate PR Prevention System
+
+Comprehensive system to prevent duplicate PRs from being created for the same issue.
+
+## Problem
+
+Despite having tools to detect and clean up duplicate PRs, agents were still creating duplicate PRs for the same issue. This was incredibly ironic, especially for issue #1128 which was about cleaning up duplicate PRs.
+
+## Solution
+
+### 1. Pre-flight Check Scripts
+
+#### `scripts/check-existing-prs.sh` (Bash)
+
+Check if an issue already has open PRs before creating a new one.
+
+```bash
+./scripts/check-existing-prs.sh 1524
+```
+
+**Exit codes:**
+- `0`: No existing PRs found (safe to create new PR)
+- `1`: Existing PRs found (do not create new PR)
+- `2`: Error (API failure, missing parameters, etc.)
+
+#### `scripts/check_existing_prs.py` (Python)
+
+Python version of the check with more features:
+
+```bash
+python scripts/check_existing_prs.py 1524
+python scripts/check_existing_prs.py --issue 1524
+```
+
+#### `scripts/pr-safe.sh` (User-friendly wrapper)
+
+Guides you through safe PR creation:
+
+```bash
+./scripts/pr-safe.sh 1524
+./scripts/pr-safe.sh 1524 fix/my-branch
+```
+
+### 2. Fixed Existing Script
+
+Fixed syntax error in `scripts/cleanup-duplicate-prs.sh` (line 21) and AUTH header format.
+
+### 3. Prevention Strategy
+
+1. **Pre-flight Checks**: Always check before creating a PR
+2. **Agent Discipline**: Add to agent instructions to check before creating PRs
+3. **Tooling Integration**: Integrate into existing workflows
+
+## Usage
+
+### Before Creating a PR
+
+```bash
+# Check if issue already has PRs
+./scripts/check-existing-prs.sh <issue_number>
+
+# If exit code is 0, safe to proceed
+# If exit code is 1, review existing PRs first
+```
+
+### In Agent Instructions
+
+Add to your agent instructions:
+
+```
+Before creating a PR for any issue:
+1. Run: ./scripts/check-existing-prs.sh <issue_number>
+2. If exit code is 1, STOP and review existing PRs
+3. Only proceed if exit code is 0
+```
+
+### Cleanup Existing Duplicates
+
+```bash
+# Show what would be done
+./scripts/cleanup-duplicate-prs.sh --dry-run
+
+# Actually close duplicates
+./scripts/cleanup-duplicate-prs.sh --close
+```
+
+## Integration
+
+### CI/CD
+
+Add to your CI pipeline:
+
+```yaml
+- name: Check for duplicate PRs
+  run: ./scripts/check-existing-prs.sh ${{ github.event.pull_request.number }}
+```
+
+### Git Hooks
+
+Add to `.git/hooks/pre-push`:
+
+```bash
+#!/bin/bash
+# Extract issue number from branch name
+ISSUE=$(git branch --show-current | grep -oE '[0-9]+$')
+if [ -n "$ISSUE" ]; then
+    ./scripts/check-existing-prs.sh "$ISSUE"
+fi
+```
+
+## Best Practices
+
+1. **Always check before creating PRs** — use the pre-flight check
+2. **Close duplicates promptly** — don't let them accumulate
+3. **Reference issues in PRs** — makes duplicate detection possible
+4. **Use descriptive branch names** — helps identify purpose
+5. **Review existing PRs first** — don't assume you're the first
+
+## Troubleshooting
+
+### "Duplicate PR detected" error
+
+This means a PR already exists for the issue. Options:
+1. Review the existing PR and contribute to it
+2. Close your PR if it's truly a duplicate
+3. Update your PR to address a different aspect
+
+### Pre-flight check not working
+
+Check that:
+1. Gitea token is configured at `~/.config/gitea/token`
+2. You have network access to the Gitea instance
+3. The repository name is correct in the script
+
+### False positives
+
+The check looks for issue numbers in PR body. If you're referencing an issue without intending to fix it, use "Refs #" instead of "Fixes #".
+
+## Related Issues
+
+- #1474: [META] Still creating duplicate PRs for issue #1128 despite cleanup
+- #1128: Original duplicate PR cleanup issue
+- #1500: observation: #1474 already has 2 open PRs — prevented another duplicate

scripts/check-existing-prs.sh

@@ -0,0 +1,95 @@
+#!/bin/bash
+# check-existing-prs.sh — Pre-flight check for duplicate PRs
+# Usage: ./scripts/check-existing-prs.sh <issue_number>
+#
+# Exit codes:
+#   0: No existing PRs found (safe to create new PR)
+#   1: Existing PRs found (do not create new PR)
+#   2: Error (API failure, missing parameters, etc.)
+
+set -euo pipefail
+
+# Configuration
+GITEA_URL="${GITEA_URL:-https://forge.alexanderwhitestone.com}"
+REPO="${GITEA_REPO:-Timmy_Foundation/the-nexus}"
+TOKEN_FILE="${HOME}/.config/gitea/token"
+
+# Colors
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m'
+
+usage() {
+    echo "Usage: $0 <issue_number>"
+    echo ""
+    echo "Check if a Gitea issue already has open PRs before creating a new one."
+    echo ""
+    echo "Exit codes:"
+    echo "  0: No existing PRs found (safe to create new PR)"
+    echo "  1: Existing PRs found (do not create new PR)"
+    echo "  2: Error (API failure, missing parameters, etc.)"
+    exit 2
+}
+
+# Parse arguments
+if [ $# -lt 1 ]; then
+    usage
+fi
+
+ISSUE_NUMBER="$1"
+
+# Validate issue number
+if ! [[ "$ISSUE_NUMBER" =~ ^[0-9]+$ ]]; then
+    echo -e "${RED}Error: Invalid issue number: $ISSUE_NUMBER${NC}" >&2
+    exit 2
+fi
+
+# Load token
+if [ ! -f "$TOKEN_FILE" ]; then
+    echo -e "${RED}Error: Gitea token not found at $TOKEN_FILE${NC}" >&2
+    exit 2
+fi
+TOKEN=$(cat "$TOKEN_FILE" | tr -d '[:space:]')
+
+# Fetch open PRs
+echo -e "${YELLOW}Checking for existing PRs referencing issue #$ISSUE_NUMBER...${NC}"
+
+RESPONSE=$(curl -s -w "\n%{http_code}" \
+    -H "Authorization: token $TOKEN" \
+    -H "Accept: application/json" \
+    "${GITEA_URL}/api/v1/repos/${REPO}/pulls?state=open" 2>/dev/null)
+
+HTTP_CODE=$(echo "$RESPONSE" | tail -1)
+BODY=$(echo "$RESPONSE" | sed '$d')
+
+if [ "$HTTP_CODE" != "200" ]; then
+    echo -e "${RED}Error: API request failed with HTTP $HTTP_CODE${NC}" >&2
+    exit 2
+fi
+
+# Check for existing PRs referencing this issue
+EXISTING_PRS=$(echo "$BODY" | python3 -c "
+import json, sys
+prs = json.load(sys.stdin)
+issue = '#$ISSUE_NUMBER'
+found = []
+for pr in prs:
+    body = (pr.get('body') or '') + ' ' + (pr.get('title') or '')
+    if issue in body:
+        found.append(f\"  #{pr['number']}: {pr['title']} ({pr['head']['ref']})\")
+if found:
+    print('\\n'.join(found))
+" 2>/dev/null)
+
+if [ -n "$EXISTING_PRS" ]; then
+    echo -e "${RED}✗ Found existing PRs for issue #$ISSUE_NUMBER:${NC}"
+    echo "$EXISTING_PRS"
+    echo ""
+    echo -e "${YELLOW}Do not create another PR. Review existing PRs instead.${NC}"
+    exit 1
+else
+    echo -e "${GREEN}✓ No existing PRs found for issue #$ISSUE_NUMBER${NC}"
+    echo -e "${GREEN}Safe to create new PR.${NC}"
+    exit 0
+fi

scripts/check_existing_prs.py

@@ -0,0 +1,111 @@
+#!/usr/bin/env python3
+"""
+check_existing_prs.py — Pre-flight check for duplicate PRs (Python version)
+
+Usage:
+    python scripts/check_existing_prs.py <issue_number>
+    python scripts/check_existing_prs.py --issue 1524
+
+Exit codes:
+    0: No existing PRs found (safe to create new PR)
+    1: Existing PRs found (do not create new PR)
+    2: Error (API failure, missing parameters, etc.)
+"""
+
+import argparse
+import json
+import os
+import sys
+import urllib.request
+import urllib.error
+from pathlib import Path
+
+# Configuration
+GITEA_URL = os.environ.get("GITEA_URL", "https://forge.alexanderwhitestone.com")
+REPO = os.environ.get("GITEA_REPO", "Timmy_Foundation/the-nexus")
+TOKEN_PATH = Path.home() / ".config" / "gitea" / "token"
+
+# ANSI colors
+RED = "\033[0;31m"
+GREEN = "\033[0;32m"
+YELLOW = "\033[1;33m"
+NC = "\033[0m"
+
+
+def load_token() -> str:
+    """Load Gitea API token."""
+    if TOKEN_PATH.exists():
+        return TOKEN_PATH.read_text().strip()
+    return os.environ.get("GITEA_TOKEN", "")
+
+
+def check_existing_prs(issue_number: int, token: str) -> list:
+    """Check if issue already has open PRs.
+    
+    Returns list of existing PR dicts, or empty list if none found.
+    """
+    url = f"{GITEA_URL}/api/v1/repos/{REPO}/pulls?state=open"
+    headers = {
+        "Authorization": f"token {token}",
+        "Accept": "application/json",
+    }
+    
+    try:
+        req = urllib.request.Request(url, headers=headers)
+        with urllib.request.urlopen(req, timeout=30) as resp:
+            prs = json.loads(resp.read())
+    except urllib.error.HTTPError as e:
+        print(f"{RED}Error: API request failed with HTTP {e.code}{NC}", file=sys.stderr)
+        return []
+    except Exception as e:
+        print(f"{RED}Error: {e}{NC}", file=sys.stderr)
+        return []
+    
+    # Find PRs referencing this issue
+    issue_ref = f"#{issue_number}"
+    existing = []
+    for pr in prs:
+        body = (pr.get("body") or "") + " " + (pr.get("title") or "")
+        if issue_ref in body:
+            existing.append(pr)
+    
+    return existing
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Check for existing PRs before creating new one")
+    parser.add_argument("issue_number", nargs="?", type=int, help="Issue number to check")
+    parser.add_argument("--issue", "-i", type=int, help="Issue number (alternative syntax)")
+    args = parser.parse_args()
+    
+    issue_number = args.issue_number or args.issue
+    if not issue_number:
+        print(f"{RED}Error: Issue number required{NC}", file=sys.stderr)
+        print("Usage: python check_existing_prs.py <issue_number>", file=sys.stderr)
+        sys.exit(2)
+    
+    # Load token
+    token = load_token()
+    if not token:
+        print(f"{RED}Error: Gitea token not found{NC}", file=sys.stderr)
+        sys.exit(2)
+    
+    # Check for existing PRs
+    print(f"{YELLOW}Checking for existing PRs referencing issue #{issue_number}...{NC}")
+    existing = check_existing_prs(issue_number, token)
+    
+    if existing:
+        print(f"{RED}✗ Found existing PRs for issue #{issue_number}:{NC}")
+        for pr in existing:
+            print(f"  #{pr['number']}: {pr['title']} ({pr['head']['ref']})")
+        print()
+        print(f"{YELLOW}Do not create another PR. Review existing PRs instead.{NC}")
+        sys.exit(1)
+    else:
+        print(f"{GREEN}✓ No existing PRs found for issue #{issue_number}{NC}")
+        print(f"{GREEN}Safe to create new PR.{NC}")
+        sys.exit(0)
+
+
+if __name__ == "__main__":
+    main()

scripts/pr-safe.sh

@@ -0,0 +1,80 @@
+#!/bin/bash
+# pr-safe.sh — User-friendly wrapper for PR creation with duplicate prevention
+# Usage: ./scripts/pr-safe.sh <issue_number> [branch_name]
+#
+# This script:
+# 1. Checks for existing PRs
+# 2. Guides you through safe PR creation
+# 3. Prevents duplicate PRs
+
+set -euo pipefail
+
+# Colors
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+NC='\033[0m'
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+usage() {
+    echo "Usage: $0 <issue_number> [branch_name]"
+    echo ""
+    echo "Safe PR creation with duplicate prevention."
+    echo ""
+    echo "Examples:"
+    echo "  $0 1524                    # Create PR for issue #1524"
+    echo "  $0 1524 fix/my-branch      # Create PR with specific branch name"
+    echo ""
+    exit 1
+}
+
+# Parse arguments
+if [ $# -lt 1 ]; then
+    usage
+fi
+
+ISSUE_NUMBER="$1"
+BRANCH_NAME="${2:-fix/issue-${ISSUE_NUMBER}-$(date +%s)}"
+
+echo -e "${BLUE}╔════════════════════════════════════════════════════════════╗${NC}"
+echo -e "${BLUE}║  Safe PR Creation for Issue #${ISSUE_NUMBER}${NC}"
+echo -e "${BLUE}╚════════════════════════════════════════════════════════════╝${NC}"
+echo ""
+
+# Step 1: Check for existing PRs
+echo -e "${YELLOW}Step 1: Checking for existing PRs...${NC}"
+if ! "${SCRIPT_DIR}/check-existing-prs.sh" "$ISSUE_NUMBER"; then
+    echo ""
+    echo -e "${RED}Cannot create PR — existing PRs found.${NC}"
+    echo -e "${YELLOW}Options:${NC}"
+    echo "  1. Review and contribute to existing PRs"
+    echo "  2. Close your local changes if truly duplicate"
+    echo "  3. Update your PR to address a different aspect"
+    exit 1
+fi
+
+echo ""
+
+# Step 2: Create branch
+echo -e "${YELLOW}Step 2: Creating branch ${BRANCH_NAME}...${NC}"
+git checkout -b "$BRANCH_NAME" 2>/dev/null || {
+    echo -e "${YELLOW}Branch already exists, switching to it.${NC}"
+    git checkout "$BRANCH_NAME"
+}
+
+echo ""
+
+# Step 3: Guide through commit
+echo -e "${YELLOW}Step 3: Make your changes and commit.${NC}"
+echo "  git add -A"
+echo "  git commit -m 'fix: implementation for #${ISSUE_NUMBER}'"
+echo ""
+
+# Step 4: Push and create PR
+echo -e "${YELLOW}Step 4: Push and create PR.${NC}"
+echo "  git push -u origin ${BRANCH_NAME}"
+echo ""
+
+echo -e "${GREEN}✓ Ready to create PR safely!${NC}"