dbs: add url scoring columns to uris table

Migration functions for check_interval, working_ratio, avg_fetch_time,
last_worker, and yield_rate columns with sensible defaults.

dbs.py

@@ -98,6 +98,51 @@ def _migrate_last_seen(sqlite):
         sqlite.commit()
 
 
+def _migrate_uri_check_interval(sqlite):
+    """Add adaptive check_interval column to uris table."""
+    try:
+        sqlite.execute('SELECT check_interval FROM uris LIMIT 1')
+    except Exception:
+        sqlite.execute('ALTER TABLE uris ADD COLUMN check_interval INT DEFAULT 3600')
+        sqlite.commit()
+
+
+def _migrate_uri_working_ratio(sqlite):
+    """Add working_ratio column to uris table for proxy quality tracking."""
+    try:
+        sqlite.execute('SELECT working_ratio FROM uris LIMIT 1')
+    except Exception:
+        sqlite.execute('ALTER TABLE uris ADD COLUMN working_ratio REAL DEFAULT 0.0')
+        sqlite.commit()
+
+
+def _migrate_uri_avg_fetch_time(sqlite):
+    """Add avg_fetch_time column to uris table for fetch latency EMA."""
+    try:
+        sqlite.execute('SELECT avg_fetch_time FROM uris LIMIT 1')
+    except Exception:
+        sqlite.execute('ALTER TABLE uris ADD COLUMN avg_fetch_time INT DEFAULT 0')
+        sqlite.commit()
+
+
+def _migrate_uri_last_worker(sqlite):
+    """Add last_worker column to uris table."""
+    try:
+        sqlite.execute('SELECT last_worker FROM uris LIMIT 1')
+    except Exception:
+        sqlite.execute('ALTER TABLE uris ADD COLUMN last_worker TEXT')
+        sqlite.commit()
+
+
+def _migrate_uri_yield_rate(sqlite):
+    """Add yield_rate column to uris table for proxy yield EMA."""
+    try:
+        sqlite.execute('SELECT yield_rate FROM uris LIMIT 1')
+    except Exception:
+        sqlite.execute('ALTER TABLE uris ADD COLUMN yield_rate REAL DEFAULT 0.0')
+        sqlite.commit()
+
+
 def compute_proxy_list_hash(proxies):
     """Compute MD5 hash of sorted proxy list for change detection.
 
@@ -356,6 +401,11 @@ def create_table_if_not_exists(sqlite, dbname):
             content_hash TEXT)""")
         # Migration for existing databases
         _migrate_content_hash_column(sqlite)
+        _migrate_uri_check_interval(sqlite)
+        _migrate_uri_working_ratio(sqlite)
+        _migrate_uri_avg_fetch_time(sqlite)
+        _migrate_uri_last_worker(sqlite)
+        _migrate_uri_yield_rate(sqlite)
         # Indexes for common query patterns
         sqlite.execute('CREATE INDEX IF NOT EXISTS idx_uris_error ON uris(error)')
         sqlite.execute('CREATE INDEX IF NOT EXISTS idx_uris_checktime ON uris(check_time)')