fix: feed a valid sha-truncated inHash in bb_prover_parity test

ParityPublicInputs requires inHash to be a 31-byte (top-byte-zero) sha frontier
root; the InboxParity circuit passes in_hash through unconstrained, so a raw
Fr.random() input reappears in the output and fails the constructor check.
Compute inHash from the messages instead.

Author: spalladino

yarn-project/prover-client/src/test/bb_prover_parity.test.ts

@@ -5,7 +5,7 @@ import { createLogger } from '@aztec/foundation/log';
 import type { ServerProtocolArtifact } from '@aztec/noir-protocol-circuits-types/server';
 import { ServerCircuitVks } from '@aztec/noir-protocol-circuits-types/server/vks';
 import { getVKTreeRoot } from '@aztec/noir-protocol-circuits-types/vk-tree';
-import { L1ToL2MessageSponge } from '@aztec/stdlib/messaging';
+import { L1ToL2MessageSponge, computeInHashFromL1ToL2Messages } from '@aztec/stdlib/messaging';
 import { INBOX_PARITY_SIZES, InboxParityPrivateInputs, type InboxParitySize } from '@aztec/stdlib/parity';
 
 import { TestContext } from '../mocks/test_context.js';
@@ -48,7 +48,9 @@ describe('prover/bb_prover/parity', () => {
       // Fill the rung with real messages so `numMessages === size` (the largest circuit for that rung).
       const messages = Array.from({ length: size }, () => Fr.random());
       const proverId = Fr.random();
-      const inHash = Fr.random();
+      // The in_hash is a sha256 frontier root (top byte zeroed to fit the field), which `ParityPublicInputs` enforces;
+      // compute it from the messages rather than using a raw random field.
+      const inHash = computeInHashFromL1ToL2Messages(messages);
 
       const inputs = InboxParityPrivateInputs.fromMessages(
         messages,