fix: add is_dummy and is_last_layer constraints

Author: shuklaayush

crates/recursion/src/gkr/layer/air.rs

@@ -138,6 +138,11 @@ where
         let is_transition = LoopSubAir::local_is_transition(next.is_enabled, next.is_first);
         let is_last = LoopSubAir::local_is_last(local.is_enabled, next.is_enabled, next.is_first);
 
+        // A proof can't contribute both dummy and non-dummy rows
+        builder
+            .when(is_transition.clone())
+            .assert_eq(next.is_dummy, local.is_dummy);
+
         // Layer index starts from 0
         builder.when(local.is_first).assert_zero(local.layer_idx);
         // Layer index increments by 1

crates/recursion/src/gkr/sumcheck/air.rs

@@ -151,9 +151,19 @@ where
             LoopSubAir::local_is_transition(next.is_enabled, next.is_first_round);
         let is_last_round =
             LoopSubAir::local_is_last(local.is_enabled, next.is_enabled, next.is_first_round);
+        let is_transition_proof = next.is_enabled - next.is_proof_start;
+
+        // A proof can't contribute both dummy and non-dummy rows
+        builder
+            .when(is_transition_proof)
+            .assert_eq(next.is_dummy, local.is_dummy);
 
         // Sumcheck round flag starts at 0
         builder.when(local.is_first_round).assert_zero(local.round);
+        // Layer metadata must remain same
+        builder
+            .when(is_transition_round.clone())
+            .assert_eq(next.is_last_layer, local.is_last_layer);
         // Sumcheck round flag increments by 1
         builder
             .when(is_transition_round.clone())

crates/recursion/src/gkr/xi_sampler/air.rs

@@ -103,6 +103,11 @@ where
         let is_last_challenge =
             LoopSubAir::local_is_last(local.is_enabled, next.is_enabled, next.is_first_challenge);
 
+        // A proof can't contribute both dummy and non-dummy rows
+        builder
+            .when(is_transition_challenge.clone())
+            .assert_eq(next.is_dummy, local.is_dummy);
+
         // Challenge index increments by 1
         builder
             .when(is_transition_challenge.clone())