test(builder): hermetic pin for script-witness preservation; tighten non-owner and submit assertions

Closes an Opus review round on Task 5's registry integration work.

Adds packages/builder/test/sign-helper.test.ts (top-level test/, picked up
by the unit glob) as the first hermetic gate that would fail if
signWithMnemonic's witness-preservation fix regressed. Before this, the
fix had zero coverage under any required gate: sign-helper.ts lives under
test/integration/, outside the unit glob; run.test.ts's
assertSuccessOrKnownError swallows the resulting "Failed to submit
transaction" as an indistinguishable known error; and the E2E's
hash-equality check can't catch it either, since dropping witnesses never
changes the transaction body hash - only the ledger tells the two apart,
and this test never talks to it. The new test builds a synthetic,
fully-offline script-bearing transaction directly via CML (one input/
output, a witness set carrying one PlutusV3 script, one map-form redeemer,
one datum), signs it with a public, well-known, never-funded BIP39 test
vector (computed from the installed bip39 package rather than transcribed
from memory - the first guess had the wrong checksum word and failed
loudly), and asserts every witness category plus the vkey witness survive
signing with the body hash unchanged. Proved it's load-bearing: reverted
the fix to the buggy from-scratch witness set, watched the test fail
naming the exact lost witness, reverted back (byte-identical, zero diff),
re-ran green.

registry-keyless.test.ts: the non-owner-update assertion drops its second
regex alternative (`Failed to build agent update`), which was a superset
match able to hide a real, unrelated build failure behind the same
"ownership was correctly refused" label. Now asserts the specific
`Ownership check failed` message only.

run.test.ts: buildSignSubmit now hard-asserts `Transaction Submitted` on
the submit leg when walletHasAda is true, instead of routing through the
tolerant assertSuccessOrKnownError - on a funded wallet a submit failure
is a real regression, not indistinguishable from an unfunded wallet, and
should fail the test rather than pass silently as a "known error". The
graceful path is kept for the unfunded case. Also documents, in a comment,
the known/accepted risk that a register-succeeds/deregister-fails run in
this file leaves the 10 AP3X test deposit locked on-chain (same shape as
the pre-keyless suite).

Hermetic only this round, per instruction: no live network calls, no
transaction submissions, no real secrets. Full account in
.superpowers/sdd/task-5-report.md's Addendum section.

Gates: typecheck 0, unit 351/351 (350 + 1 new), smoke 26/26, auth 12/12,
boundary 4/4 (confirms the new test's mnemonic constant sits outside the
custody scan by design, same as the rest of test/, and is labeled
TEST_ONLY_PUBLIC_MNEMONIC regardless per public-repo hygiene).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/builder/test/sign-helper.test.ts

@@ -0,0 +1,113 @@
+// packages/builder/test/sign-helper.test.ts
+//
+// Hermetic pin for signWithMnemonic's witness-preservation fix
+// (test/integration/sign-helper.ts). Proves offline, with zero network
+// access and zero real secrets, that signing a script-bearing transaction
+// preserves its existing plutus_v3_scripts/redeemers/plutus_datums instead
+// of discarding them - the defect found live during Task 5's gated E2E run
+// (see task-5-report.md, "Bug #1").
+//
+// Why this needs its own test: none of the existing gates catch this
+// mutant. sign-helper.ts lives under test/integration/, outside every unit
+// test glob (packages/*/test/*.test.ts is non-recursive). run.test.ts's
+// assertSuccessOrKnownError treats the resulting "Failed to submit
+// transaction" as a tolerated known error (indistinguishable from an
+// unfunded wallet) rather than a hard failure. And registry-e2e.test.ts's
+// hash-equality check (`assert.equal(submittedHash, txHash, ...)`) cannot
+// catch it either: dropping witnesses never changes the transaction BODY,
+// so the mutant computes the exact same body hash as the fix - only the
+// ledger, which this test never talks to, rejects the mutant's CBOR. This
+// file is the only gate that would fail if the fix regressed.
+import { describe, test } from 'node:test';
+import assert from 'node:assert/strict';
+import { CML, walletFromSeed } from '@lucid-evolution/lucid';
+import { signWithMnemonic } from './integration/sign-helper.ts';
+
+// Public BIP39 test vector: 23x "abandon" + the checksum word "art" (the
+// 24-word encoding of all-zero, 256-bit entropy - verified directly against
+// the `bip39` package's own entropyToMnemonic(), not transcribed from
+// memory: `bip39.entropyToMnemonic('00'.repeat(32))`). This is the
+// canonical example mnemonic used throughout the crypto tooling ecosystem
+// specifically because it is universally known, was never funded, and
+// holds nothing on any network. TEST-ONLY - used here purely to exercise
+// signing logic offline; never use it, or any mnemonic like it, for
+// anything that touches real funds.
+const TEST_ONLY_PUBLIC_MNEMONIC =
+  'abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon ' +
+  'abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon art';
+
+/**
+ * Builds a synthetic, offline, script-bearing unsigned transaction: one
+ * input, one output, and a witness set carrying one PlutusV3 script, one
+ * redeemer, and one datum - enough to exercise every witness-set category
+ * signWithMnemonic must preserve, without a live network, a real validator,
+ * or Lucid's TransactionBuilder (whose min-UTxO/fee rules this probe has no
+ * reason to satisfy: these are raw CML data containers, hashed and
+ * re-serialized, never evaluated or submitted anywhere).
+ */
+function buildSyntheticScriptBearingTx(): string {
+  const { address } = walletFromSeed(TEST_ONLY_PUBLIC_MNEMONIC, { network: 'Mainnet', accountIndex: 0 });
+  const addr = CML.Address.from_bech32(address);
+
+  const inputs = CML.TransactionInputList.new();
+  inputs.add(CML.TransactionInput.new(CML.TransactionHash.from_hex('00'.repeat(32)), 0n));
+
+  const outputs = CML.TransactionOutputList.new();
+  outputs.add(CML.TransactionOutput.new(addr, CML.Value.from_coin(2_000_000n)));
+
+  const body = CML.TransactionBody.new(inputs, outputs, 200_000n);
+
+  const witnessSet = CML.TransactionWitnessSet.new();
+
+  const scripts = CML.PlutusV3ScriptList.new();
+  scripts.add(CML.PlutusV3Script.from_hex('4e4d01000033222220051200120011'));
+  witnessSet.set_plutus_v3_scripts(scripts);
+
+  const redeemerMap = CML.MapRedeemerKeyToRedeemerVal.new();
+  redeemerMap.insert(
+    CML.RedeemerKey.new(CML.RedeemerTag.Mint, 0n),
+    CML.RedeemerVal.new(CML.PlutusData.new_bytes(new Uint8Array([1, 2, 3])), CML.ExUnits.new(1_000n, 1_000n)),
+  );
+  witnessSet.set_redeemers(CML.Redeemers.new_map_redeemer_key_to_redeemer_val(redeemerMap));
+
+  const datums = CML.PlutusDataList.new();
+  datums.add(CML.PlutusData.new_bytes(new Uint8Array([9, 9, 9])));
+  witnessSet.set_plutus_datums(datums);
+
+  return CML.Transaction.new(body, witnessSet, true).to_cbor_hex();
+}
+
+describe('signWithMnemonic preserves an existing script witness set (hermetic pin, task-5-report.md Bug #1)', () => {
+  test('signing a script-bearing tx keeps the vkey witness AND the original scripts/redeemers/datums, and leaves the body hash unchanged', () => {
+    const unsignedCborHex = buildSyntheticScriptBearingTx();
+    const unsignedBodyHashHex = CML.hash_transaction(CML.Transaction.from_cbor_hex(unsignedCborHex).body()).to_hex();
+
+    const { signedCborHex, txHash } = signWithMnemonic(unsignedCborHex, TEST_ONLY_PUBLIC_MNEMONIC);
+
+    assert.equal(txHash, unsignedBodyHashHex, 'signing must not change the transaction body hash');
+
+    const signed = CML.Transaction.from_cbor_hex(signedCborHex);
+    assert.equal(
+      CML.hash_transaction(signed.body()).to_hex(), unsignedBodyHashHex,
+      'the signed tx body hash must still match the unsigned one',
+    );
+
+    const ws = signed.witness_set();
+
+    const vkeys = ws.vkeywitnesses();
+    assert.ok(vkeys && vkeys.len() === 1, `expected exactly 1 vkey witness after signing, got ${vkeys?.len() ?? 0}`);
+
+    const scripts = ws.plutus_v3_scripts();
+    assert.ok(scripts && scripts.len() === 1, `expected the original plutus_v3 script to survive signing, got ${scripts?.len() ?? 0}`);
+
+    const redeemers = ws.redeemers();
+    assert.ok(redeemers, 'expected the original redeemers to survive signing (got none)');
+    assert.equal(
+      redeemers!.as_map_redeemer_key_to_redeemer_val()?.len(), 1,
+      'expected exactly 1 redeemer to survive signing',
+    );
+
+    const datums = ws.plutus_datums();
+    assert.ok(datums && datums.len() === 1, `expected the original plutus datum to survive signing, got ${datums?.len() ?? 0}`);
+  });
+});