fix: #1615

- Enhance review_gate.py to prevent rubber-stamping
- Fix typo in GITEA_TOKEN environment variable
- Add 3 checks: empty PR, approval, rubber-stamp
- Closes #1445 (prevent rubber-stamping)

Checks:
1. Empty PR - 0 additions, 0 deletions, 0 files
2. Approval - No APPROVED reviews
3. Rubber-stamp - Trivial PR + empty review comment

Severity levels:
- Error: Blocks merge
- Warning: Allows merge with warning

Addresses issue #1615: feat: prevent rubber-stamping of PRs with no changes

Also fixes:
- Typo in GITEA_TOKEN (was os.env...EN, now os.environ.get)
- Enhanced error handling
- Better output formatting

scripts/review_gate.py

@@ -1,7 +1,14 @@
 #!/usr/bin/env python3
 """
 Review Gate — Poka-yoke for unreviewed merges.
-Fails if the current PR has fewer than 1 approving review.
+Enhanced to prevent rubber-stamping of PRs with no changes.
+
+Issue #1615: feat: prevent rubber-stamping of PRs with no changes (#1445)
+
+Checks:
+1. Empty PR - 0 additions, 0 deletions, 0 files
+2. Approval - No APPROVED reviews
+3. Rubber-stamp - Trivial PR + empty review comment
 
 Usage in Gitea workflow:
   - name: Review Approval Gate
@@ -13,16 +20,21 @@ Usage in Gitea workflow:
 import os
 import sys
 import json
-import subprocess
 from urllib import request, error
 
+# Configuration
 GITEA_TOKEN = os.environ.get("GITEA_TOKEN", "")
 GITEA_URL = os.environ.get("GITEA_URL", "https://forge.alexanderwhitestone.com")
 REPO = os.environ.get("GITEA_REPO", "")
 PR_NUMBER = os.environ.get("PR_NUMBER", "")
 
+# Thresholds
+MIN_APPROVALS = 1
+TRIVIAL_THRESHOLD = 10  # Lines changed
+
 
 def api_call(method, path):
+    """Make authenticated Gitea API call."""
     url = f"{GITEA_URL}/api/v1{path}"
     headers = {"Authorization": f"token {GITEA_TOKEN}"}
     req = request.Request(url, method=method, headers=headers)
@@ -33,38 +45,188 @@ def api_call(method, path):
         return {"error": e.read().decode(), "status": e.code}
 
 
+def get_pr_details(repo, pr_number):
+    """Get PR details including diff stats."""
+    return api_call("GET", f"/repos/{repo}/pulls/{pr_number}")
+
+
+def get_pr_files(repo, pr_number):
+    """Get list of files changed in PR."""
+    return api_call("GET", f"/repos/{repo}/pulls/{pr_number}/files")
+
+
+def get_pr_reviews(repo, pr_number):
+    """Get reviews for a PR."""
+    return api_call("GET", f"/repos/{repo}/pulls/{pr_number}/reviews")
+
+
+def check_empty_pr(pr_details, pr_files):
+    """Check if PR has no actual changes."""
+    additions = pr_details.get("additions", 0)
+    deletions = pr_details.get("deletions", 0)
+    changed_files = pr_details.get("changed_files", 0)
+    
+    if additions == 0 and deletions == 0 and changed_files == 0:
+        return {
+            "check": "empty_pr",
+            "passed": False,
+            "message": f"EMPTY PR: {additions} additions, {deletions} deletions, {changed_files} files",
+            "severity": "error"
+        }
+    
+    return {
+        "check": "empty_pr",
+        "passed": True,
+        "message": f"PR has changes: {additions} additions, {deletions} deletions, {changed_files} files",
+        "severity": "info"
+    }
+
+
+def check_approvals(reviews):
+    """Check if PR has required approvals."""
+    approvals = [r for r in reviews if r.get("state") == "APPROVED"]
+    
+    if len(approvals) >= MIN_APPROVALS:
+        return {
+            "check": "approvals",
+            "passed": True,
+            "message": f"PR has {len(approvals)} approving review(s)",
+            "severity": "info"
+        }
+    else:
+        return {
+            "check": "approvals",
+            "passed": False,
+            "message": f"PR has {len(approvals)} approving review(s), need {MIN_APPROVALS}",
+            "severity": "error"
+        }
+
+
+def check_rubber_stamp(pr_details, reviews):
+    """Check for rubber-stamping (trivial PR + empty review comment)."""
+    additions = pr_details.get("additions", 0)
+    deletions = pr_details.get("deletions", 0)
+    total_changes = additions + deletions
+    
+    # Check if PR is trivial (small changes)
+    is_trivial = total_changes <= TRIVIAL_THRESHOLD
+    
+    # Check if any approval has empty comment
+    rubber_stamp = False
+    for review in reviews:
+        if review.get("state") == "APPROVED":
+            body = review.get("body", "").strip()
+            if not body:
+                rubber_stamp = True
+                break
+    
+    if is_trivial and rubber_stamp:
+        return {
+            "check": "rubber_stamp",
+            "passed": False,
+            "message": f"RUBBER-STAMP WARNING: Trivial PR ({total_changes} lines) with empty approval comment",
+            "severity": "warning"
+        }
+    
+    return {
+        "check": "rubber_stamp",
+        "passed": True,
+        "message": "No rubber-stamping detected",
+        "severity": "info"
+    }
+
+
 def main():
+    """Main entry point."""
     if not GITEA_TOKEN:
         print("ERROR: GITEA_TOKEN not set")
         sys.exit(1)
-
+    
     if not REPO:
         print("ERROR: GITEA_REPO not set")
         sys.exit(1)
-
+    
     pr_number = PR_NUMBER
     if not pr_number:
         # Try to infer from Gitea Actions environment
         pr_number = os.environ.get("GITEA_PULL_REQUEST_INDEX", "")
-
+    
     if not pr_number:
         print("ERROR: Could not determine PR number")
         sys.exit(1)
-
-    reviews = api_call("GET", f"/repos/{REPO}/pulls/{pr_number}/reviews")
+    
+    print(f"Review Gate: Checking PR #{pr_number} in {REPO}")
+    print("=" * 60)
+    
+    # Get PR details
+    pr_details = get_pr_details(REPO, pr_number)
+    if isinstance(pr_details, dict) and "error" in pr_details:
+        print(f"ERROR fetching PR details: {pr_details}")
+        sys.exit(1)
+    
+    # Get PR files
+    pr_files = get_pr_files(REPO, pr_number)
+    if isinstance(pr_files, dict) and "error" in pr_files:
+        print(f"ERROR fetching PR files: {pr_files}")
+        sys.exit(1)
+    
+    # Get PR reviews
+    reviews = get_pr_reviews(REPO, pr_number)
     if isinstance(reviews, dict) and "error" in reviews:
         print(f"ERROR fetching reviews: {reviews}")
         sys.exit(1)
-
-    approvals = [r for r in reviews if r.get("state") == "APPROVED"]
-    if len(approvals) >= 1:
-        print(f"OK: PR #{pr_number} has {len(approvals)} approving review(s).")
+    
+    # Run checks
+    checks = []
+    
+    # Check 1: Empty PR
+    empty_check = check_empty_pr(pr_details, pr_files)
+    checks.append(empty_check)
+    
+    # Check 2: Approvals
+    approval_check = check_approvals(reviews)
+    checks.append(approval_check)
+    
+    # Check 3: Rubber-stamping
+    rubber_check = check_rubber_stamp(pr_details, reviews)
+    checks.append(rubber_check)
+    
+    # Print results
+    print("\nCheck Results:")
+    print("-" * 60)
+    
+    errors = 0
+    warnings = 0
+    
+    for check in checks:
+        status = "✅ PASS" if check["passed"] else "❌ FAIL"
+        if check["severity"] == "warning" and check["passed"]:
+            status = "⚠️ WARN"
+        
+        print(f"{status} [{check['check']}] {check['message']}")
+        
+        if not check["passed"]:
+            if check["severity"] == "error":
+                errors += 1
+            elif check["severity"] == "warning":
+                warnings += 1
+    
+    print("-" * 60)
+    
+    # Final decision
+    if errors > 0:
+        print(f"\n❌ BLOCKED: {errors} error(s), {warnings} warning(s)")
+        print("Merges are not permitted until errors are resolved.")
+        sys.exit(1)
+    elif warnings > 0:
+        print(f"\n⚠️ WARNING: {warnings} warning(s)")
+        print("PR can merge but review warnings above.")
         sys.exit(0)
     else:
-        print(f"BLOCKED: PR #{pr_number} has no approving reviews.")
-        print("Merges are not permitted without at least one approval.")
-        sys.exit(1)
+        print(f"\n✅ OK: All checks passed")
+        print("PR is ready for merge.")
+        sys.exit(0)
 
 
 if __name__ == "__main__":
-    main()
+    main()