chore: clarify bracket-head rule semantics

Agent-Logs-Url: https://github.com/microsoft/regorus/sessions/272a971a-ae52-45ae-8cb3-714e747599c4

Co-authored-by: anakrish <35780660+anakrish@users.noreply.github.com>

src/interpreter.rs

@@ -1757,6 +1757,8 @@ impl Interpreter {
 
         match expr.as_ref() {
             Expr::Var { span, .. } => {
+                // A variable that is not currently bound in local scope behaves like
+                // a stable global/package reference for this evaluation.
                 let scope = self
                     .scopes
                     .last()

src/languages/rego/compiler/rules.rs

@@ -56,6 +56,8 @@ impl<'a> Compiler<'a> {
                     match head {
                         RuleHead::Set { .. } => RuleType::PartialSet,
                         RuleHead::Compr { refr, assign, .. } => match refr.as_ref() {
+                            // Variable-key bracket heads emit one object entry per successful
+                            // binding, so they must compile as partial objects.
                             crate::ast::Expr::RefBrack { index, .. }
                                 if super::expressions::try_eval_const(index.as_ref()).is_none() =>
                             {

tests/rvm/vm/suites/object_operations.yaml

@@ -8,7 +8,7 @@
 cases:
   - note: object_key_collision_conflict
     description: Setting same key twice with different values should raise a rule output conflict
-    example_rego: "p[\"key\"] := value if { value := [1, 2][_] }"
+    example_rego: "p[\"key\"] = value { value := [1, 2][_] }"
     literals:
       - {}
       - "key"