feat(database): add patent/serp caching tables and connection pooling

- Add patents table (patent_id PK, raw_sections JSONB, minimized_content)
- Add serp_queries table (query_hash unique, result_patent_ids, expires_at)
- Add cache methods: get/store_patent, get/store_serp_query
- Replace single connection with ThreadedConnectionPool (min=2, max=10)
- Add get_conn() context manager for thread-safe connection checkout
- Legacy single-connection path preserved for backwards compatibility

SPARC/database.py

@@ -1,9 +1,11 @@
 """Database client for storing and retrieving LLM messages and user authentication."""
 
+import contextlib
 import psycopg2
+from psycopg2.pool import ThreadedConnectionPool
 from psycopg2.extras import RealDictCursor
 from typing import Dict, List, Optional
-from datetime import datetime
+from datetime import datetime, timedelta
 import json
 import hashlib
 import bcrypt
@@ -12,24 +14,49 @@ import bcrypt
 class DatabaseClient:
     """Handles database operations for message storage and retrieval."""
 
-    def __init__(self, database_url: str):
+    def __init__(self, database_url: str, minconn: int = 2, maxconn: int = 10):
         """Initialize the database client.
 
         Args:
             database_url: PostgreSQL connection string
+            minconn: Minimum connections in the pool
+            maxconn: Maximum connections in the pool
         """
         self.database_url = database_url
+        self._pool: ThreadedConnectionPool | None = None
+        self._minconn = minconn
+        self._maxconn = maxconn
+        # Legacy single connection kept for backwards compatibility
         self.conn = None
 
+    def _ensure_pool(self):
+        """Create the connection pool if it doesn't exist yet."""
+        if self._pool is None or self._pool.closed:
+            self._pool = ThreadedConnectionPool(
+                self._minconn, self._maxconn, self.database_url
+            )
+
+    @contextlib.contextmanager
+    def get_conn(self):
+        """Check out a connection from the pool. Returns it on exit."""
+        self._ensure_pool()
+        conn = self._pool.getconn()
+        try:
+            yield conn
+        finally:
+            self._pool.putconn(conn)
+
     def connect(self):
-        """Establish database connection."""
+        """Establish database connection (legacy single-connection path)."""
         if not self.conn or self.conn.closed:
             self.conn = psycopg2.connect(self.database_url)
 
     def close(self):
-        """Close database connection."""
+        """Close database connection and pool."""
         if self.conn and not self.conn.closed:
             self.conn.close()
+        if self._pool and not self._pool.closed:
+            self._pool.closeall()
 
     def initialize_schema(self):
         """Create database tables if they don't exist."""
@@ -110,6 +137,40 @@ class DatabaseClient:
                 ON users(email)
             """)
 
+            # Create patents cache table
+            cursor.execute("""
+                CREATE TABLE IF NOT EXISTS patents (
+                    patent_id VARCHAR(64) PRIMARY KEY,
+                    company_name VARCHAR(255),
+                    pdf_link TEXT,
+                    raw_sections JSONB,
+                    minimized_content TEXT,
+                    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+                )
+            """)
+
+            cursor.execute("""
+                CREATE INDEX IF NOT EXISTS idx_patents_company
+                ON patents(company_name)
+            """)
+
+            # Create SERP query cache table
+            cursor.execute("""
+                CREATE TABLE IF NOT EXISTS serp_queries (
+                    id SERIAL PRIMARY KEY,
+                    company_name VARCHAR(255),
+                    query_hash VARCHAR(64) UNIQUE,
+                    result_patent_ids TEXT[],
+                    expires_at TIMESTAMP NOT NULL,
+                    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+                )
+            """)
+
+            cursor.execute("""
+                CREATE INDEX IF NOT EXISTS idx_serp_queries_hash
+                ON serp_queries(query_hash)
+            """)
+
             self.conn.commit()
 
     @staticmethod
@@ -320,6 +381,87 @@ class DatabaseClient:
                 "period_days": days,
             }
 
+    # Patent Cache Methods
+
+    def get_cached_patent(self, patent_id: str) -> Optional[Dict]:
+        """Look up a cached patent by ID.
+
+        Returns:
+            Dict with raw_sections and minimized_content, or None.
+        """
+        with self.get_conn() as conn:
+            with conn.cursor(cursor_factory=RealDictCursor) as cursor:
+                cursor.execute(
+                    "SELECT * FROM patents WHERE patent_id = %s",
+                    (patent_id,),
+                )
+                row = cursor.fetchone()
+                return dict(row) if row else None
+
+    def store_patent(
+        self,
+        patent_id: str,
+        company_name: str,
+        pdf_link: str,
+        raw_sections: Dict,
+        minimized_content: str,
+    ) -> None:
+        """Store a processed patent in the cache."""
+        with self.get_conn() as conn:
+            with conn.cursor() as cursor:
+                cursor.execute(
+                    """
+                    INSERT INTO patents (patent_id, company_name, pdf_link, raw_sections, minimized_content)
+                    VALUES (%s, %s, %s, %s, %s)
+                    ON CONFLICT (patent_id) DO UPDATE SET
+                        raw_sections = EXCLUDED.raw_sections,
+                        minimized_content = EXCLUDED.minimized_content
+                    """,
+                    (patent_id, company_name, pdf_link, json.dumps(raw_sections), minimized_content),
+                )
+            conn.commit()
+
+    def get_cached_serp_query(self, query_hash: str) -> Optional[List[str]]:
+        """Look up cached SERP query results.
+
+        Returns:
+            List of patent IDs if cache hit and not expired, None otherwise.
+        """
+        with self.get_conn() as conn:
+            with conn.cursor(cursor_factory=RealDictCursor) as cursor:
+                cursor.execute(
+                    """
+                    SELECT result_patent_ids FROM serp_queries
+                    WHERE query_hash = %s AND expires_at > NOW()
+                    """,
+                    (query_hash,),
+                )
+                row = cursor.fetchone()
+                return row["result_patent_ids"] if row else None
+
+    def store_serp_query(
+        self,
+        company_name: str,
+        query_hash: str,
+        patent_ids: List[str],
+        ttl_hours: int = 24,
+    ) -> None:
+        """Store SERP query results in the cache."""
+        expires_at = datetime.now() + timedelta(hours=ttl_hours)
+        with self.get_conn() as conn:
+            with conn.cursor() as cursor:
+                cursor.execute(
+                    """
+                    INSERT INTO serp_queries (company_name, query_hash, result_patent_ids, expires_at)
+                    VALUES (%s, %s, %s, %s)
+                    ON CONFLICT (query_hash) DO UPDATE SET
+                        result_patent_ids = EXCLUDED.result_patent_ids,
+                        expires_at = EXCLUDED.expires_at
+                    """,
+                    (company_name, query_hash, patent_ids, expires_at),
+                )
+            conn.commit()
+
     # User Authentication Methods
 
     @staticmethod