improve backfill and jetstream db connections

pkg/appview/db/schema.go

@@ -92,6 +92,16 @@ func InitDB(path string, cfg LibsqlConfig) (*sql.DB, error) {
 		return nil, err
 	}
 
+	// Bound the connection pool. With a remote target (Bunny Database), each
+	// idle conn is a stable libsql stream — keeping a handful warm avoids
+	// reconnect cost, capping the total prevents runaway contention. Short
+	// lifetimes ensure we recycle past any idle-side disconnects and drop any
+	// poisoned conn that survived IsPoisonedTxErr eviction.
+	db.SetMaxOpenConns(8)
+	db.SetMaxIdleConns(4)
+	db.SetConnMaxLifetime(5 * time.Minute)
+	db.SetConnMaxIdleTime(2 * time.Minute)
+
 	// Check if this is an existing database with migrations applied
 	isExisting, err := hasAppliedMigrations(db)
 	if err != nil {
@@ -202,20 +212,21 @@ func runMigrations(db *sql.DB, freshDB bool) error {
 		if err != nil {
 			return fmt.Errorf("failed to begin transaction for migration %d: %w", m.Version, err)
 		}
+		// Deferred rollback is a no-op once Commit succeeds; it guards against
+		// panics and any early return that forgets an explicit rollback.
+		defer func() { _ = tx.Rollback() }()
 
 		// Split query into individual statements and execute each
 		// go-sqlite3's Exec() doesn't reliably execute all statements in multi-statement queries
 		statements := splitSQLStatements(m.Query)
 		for i, stmt := range statements {
 			if _, err := tx.Exec(stmt); err != nil {
-				tx.Rollback()
 				return fmt.Errorf("failed to apply migration %d (%s) statement %d: %w", m.Version, m.Name, i+1, err)
 			}
 		}
 
 		// Record migration
 		if _, err := tx.Exec("INSERT INTO schema_migrations (version) VALUES (?)", m.Version); err != nil {
-			tx.Rollback()
 			return fmt.Errorf("failed to record migration %d: %w", m.Version, err)
 		}
 

pkg/appview/db/schema.sql

@@ -180,6 +180,12 @@ CREATE TABLE IF NOT EXISTS repository_stats_daily (
 );
 CREATE INDEX IF NOT EXISTS idx_repo_stats_daily_date ON repository_stats_daily(date DESC);
 
+CREATE TABLE IF NOT EXISTS jetstream_cursor (
+    id INTEGER PRIMARY KEY CHECK (id = 1),
+    cursor INTEGER NOT NULL,
+    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+);
+
 CREATE TABLE IF NOT EXISTS stars (
     starrer_did TEXT NOT NULL,
     owner_did TEXT NOT NULL,