fix(defaults): evaluate arbitrary DEFAULT expressions via const-fold

The DEFAULT resolver previously only handled a small set of hard-coded
keywords (NOW, UUID, etc.) and returned None for everything else.

Add a fallback path that parses the DEFAULT string through sqlparser-rs
and runs it through the planner's constant-folding evaluator, enabling
DEFAULT values like upper('hello'), 1 + 2, or concat('a', 'b') to
resolve at insert time without a Data Plane round-trip.

Also replace wrapping integer arithmetic in the const-folder with
checked variants to prevent silent overflow on constant expressions.

Author: farhan-syah

nodedb-sql/src/planner/const_fold.rs

@@ -64,9 +64,9 @@ pub fn fold_constant(expr: &SqlExpr, registry: &FunctionRegistry) -> Option<SqlV
 
 fn fold_binary(l: SqlValue, op: BinaryOp, r: SqlValue) -> Option<SqlValue> {
     Some(match (l, op, r) {
-        (SqlValue::Int(a), BinaryOp::Add, SqlValue::Int(b)) => SqlValue::Int(a + b),
-        (SqlValue::Int(a), BinaryOp::Sub, SqlValue::Int(b)) => SqlValue::Int(a - b),
-        (SqlValue::Int(a), BinaryOp::Mul, SqlValue::Int(b)) => SqlValue::Int(a * b),
+        (SqlValue::Int(a), BinaryOp::Add, SqlValue::Int(b)) => SqlValue::Int(a.checked_add(b)?),
+        (SqlValue::Int(a), BinaryOp::Sub, SqlValue::Int(b)) => SqlValue::Int(a.checked_sub(b)?),
+        (SqlValue::Int(a), BinaryOp::Mul, SqlValue::Int(b)) => SqlValue::Int(a.checked_mul(b)?),
         (SqlValue::Float(a), BinaryOp::Add, SqlValue::Float(b)) => SqlValue::Float(a + b),
         (SqlValue::Float(a), BinaryOp::Sub, SqlValue::Float(b)) => SqlValue::Float(a - b),
         (SqlValue::Float(a), BinaryOp::Mul, SqlValue::Float(b)) => SqlValue::Float(a * b),

nodedb/src/control/planner/sql_plan_convert/value/defaults.rs

@@ -67,5 +67,30 @@ fn parse_parametric_or_literal(expr: &str, upper: &str) -> Option<nodedb_types::
             trimmed[1..trimmed.len() - 1].to_string(),
         ));
     }
-    None
+
+    // Fallback: try the plan-time const-folder for arbitrary expressions
+    // (e.g. `upper('x')`, `1 + 2`, `concat('a', 'b')`).
+    try_const_fold_default(expr)
+}
+
+/// Attempt to parse the DEFAULT expression as SQL, then const-fold it.
+fn try_const_fold_default(expr: &str) -> Option<nodedb_types::Value> {
+    let sql_expr = nodedb_sql::parse_expr_string(expr).ok()?;
+    let folded = nodedb_sql::planner::const_fold::fold_constant_default(&sql_expr)?;
+    Some(sql_value_to_ndb(folded))
+}
+
+fn sql_value_to_ndb(v: nodedb_sql::types::SqlValue) -> nodedb_types::Value {
+    use nodedb_sql::types::SqlValue;
+    match v {
+        SqlValue::Null => nodedb_types::Value::Null,
+        SqlValue::Bool(b) => nodedb_types::Value::Bool(b),
+        SqlValue::Int(i) => nodedb_types::Value::Integer(i),
+        SqlValue::Float(f) => nodedb_types::Value::Float(f),
+        SqlValue::String(s) => nodedb_types::Value::String(s),
+        SqlValue::Bytes(b) => nodedb_types::Value::Bytes(b),
+        SqlValue::Array(a) => {
+            nodedb_types::Value::Array(a.into_iter().map(sql_value_to_ndb).collect())
+        }
+    }
 }