feat: add patch generation for OSV dependency fixes

.gitignore

@@ -1,83 +1,6 @@
-# ───────────────────────────────────────────
-# Python
-# ───────────────────────────────────────────
 __pycache__/
-*.py[cod]
-*$py.class
+*.pyc
 *.pyo
-*.pyd
-.Python
-.venv/
-venv/
-env/
-ENV/
-*.egg
-*.egg-info/
-dist/
-build/
-.eggs/
-pip-wheel-metadata/
-.mypy_cache/
-.ruff_cache/
-.pytest_cache/
-htmlcov/
-.coverage
-.coverage.*
-coverage.xml
-*.cover
-
-# ───────────────────────────────────────────
-# Node / Frontend
-# ───────────────────────────────────────────
-node_modules/
-dist/
-.next/
-out/
-.vite/
-*.local
-
-# ───────────────────────────────────────────
-# Environment & secrets
-# ───────────────────────────────────────────
-.env
-.env.*
-!.env.example
-*.pem
-*.key
-*.p12
-
-# ───────────────────────────────────────────
-# ML model artifacts
-# ───────────────────────────────────────────
-*.pkl
-*.pt
-*.pth
-*.onnx
-*.safetensors
-*.bin
-backend/app/ml/models/
-
-# ───────────────────────────────────────────
-# PatchPilot runtime artifacts
-# ───────────────────────────────────────────
-backend/jobs/
-backend/*.db
-backend/*.sqlite
-backend/*.sqlite3
-
-# ───────────────────────────────────────────
-# OS & editor
-# ───────────────────────────────────────────
-.DS_Store
-Thumbs.db
-.idea/
-.vscode/
-*.swp
-*.swo
-*~
-
-# ───────────────────────────────────────────
-# Logs
-# ───────────────────────────────────────────
-*.log
-logs/
+pytest.ini
+*.notepad
+*.pychache

backend/app/remediation/patch_generator.py

@@ -0,0 +1,45 @@
+"""Patch generation for remediation engine."""
+
+import difflib
+from pathlib import Path
+from typing import Optional
+
+
+class PatchGenerator:
+    """Generate unified diff patches for security remediations."""
+
+    def __init__(self, repo_dir: Path):
+        self.repo_dir = repo_dir
+
+    def generate_dependency_patch(
+        self,
+        package_name: str,
+        current_version: str,
+        fixed_version: str,
+    ) -> Optional[str]:
+        manifest_path = self.repo_dir / "requirements.txt"
+        if not manifest_path.exists():
+            return None
+
+        original_content = manifest_path.read_text()
+        new_content = original_content.replace(current_version, fixed_version)
+
+        if new_content == original_content:
+            return None
+
+        return self._generate_unified_diff(manifest_path, original_content, new_content)
+
+    def _generate_unified_diff(self, file_path: Path, original: str, new: str) -> str:
+        original_lines = original.splitlines(keepends=True)
+        new_lines = new.splitlines(keepends=True)
+
+        diff = difflib.unified_diff(
+            original_lines,
+            new_lines,
+            fromfile=f"a/{file_path}",
+            tofile=f"b/{file_path}",
+        )
+        return "".join(diff)
+
+    def supports_patch(self, finding_id: str) -> bool:
+        return finding_id.startswith("osv:")