feat(tx): live CBOR builder for Release - Submitted strays become resolvable

Release was the one escrow spend path still hardwired to the synthetic
testTxBody backend, so suppliers had no way to resolve Submitted escrows
past the accept window on mainnet (the sweeper parks them 'for supplier
Release'). Adds buildLiveTxForRelease mirroring the Reclaim builder
(supplier payout, Constr4/tag 125 redeemer, Ogmios UPLC eval) and the
detectCborBackend dispatch in buildReleaseTx, reclaim.ts-style.

validFrom clamps to submitted_at + ACCEPT_WINDOW rather than tip-60s
alone: the back-pad by itself violates the validator whenever the tip is
less than 60s past the window.

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

tests/unit/tx-release-live-dispatch.test.ts

@@ -0,0 +1,83 @@
+/**
+ * tx-release-live-dispatch.test.ts — buildReleaseTx() must route to the live
+ * CBOR builder when the chain is a LiveOgmiosProvider, mirroring reclaim.ts.
+ *
+ * Parity gap under test: Release is the one escrow spend path still hardwired
+ * to the synthetic testTxBody backend, which leaves Submitted-past-accept-window
+ * escrows unresolvable on mainnet (sweeper parks them "for supplier Release").
+ *
+ * The live builder itself needs a real wallet + Ogmios and is exercised by the
+ * mainnet fleet scripts like the other six builders; here it is mocked at the
+ * module boundary and only the dispatch contract is asserted.
+ */
+
+import { describe, it, expect, vi } from "vitest";
+
+vi.mock("../../packages/shared/src/tx/internal/liveCbor.js", () => ({
+  buildLiveTxForRelease: vi.fn(async () => ({
+    txCborHex: "live-cbor-sentinel",
+    expectedTxHash: "live-hash-sentinel",
+  })),
+}));
+
+import { buildReleaseTx } from "../../packages/shared/src/tx/escrow/release.js";
+import { LiveOgmiosProvider } from "../../packages/shared/src/chain/LiveOgmiosProvider.js";
+import { ACCEPT_WINDOW_MS } from "../../packages/shared/src/tx/escrow/accept.js";
+import * as liveCbor from "../../packages/shared/src/tx/internal/liveCbor.js";
+import { buildSupplierWalletKey } from "../fixtures/supplier-side/wallet-keys.js";
+import {
+  buildSubmittedEscrowUtxo,
+  SUBMITTED_AT,
+} from "../fixtures/buyer-side/sample-escrow-utxos.js";
+
+const RELEASE_THRESHOLD = SUBMITTED_AT + ACCEPT_WINDOW_MS;
+
+/**
+ * A stub that passes the `instanceof LiveOgmiosProvider` backend check without
+ * opening any connection. Only the methods buildReleaseTx touches pre-dispatch
+ * are provided. Tip slot is set past the accept window so that, while the
+ * dispatch gap exists, the mock path completes and returns synthetic CBOR
+ * (a clean assertion failure) instead of erroring on the window check.
+ */
+function fakeLiveChain(): LiveOgmiosProvider {
+  const utxo = buildSubmittedEscrowUtxo();
+  const fake = Object.create(LiveOgmiosProvider.prototype) as LiveOgmiosProvider;
+  Object.assign(fake, {
+    queryUtxo: async () => utxo,
+    tip: async () => Math.floor((RELEASE_THRESHOLD + 60_000) / 1000),
+    submitTx: async () => undefined,
+  });
+  return fake;
+}
+
+describe("buildReleaseTx() — live backend dispatch", () => {
+  it("routes to buildLiveTxForRelease when chain is a LiveOgmiosProvider", async () => {
+    const chain = fakeLiveChain();
+    const supplier = buildSupplierWalletKey();
+    const utxo = buildSubmittedEscrowUtxo();
+
+    const result = await buildReleaseTx({ chain, supplierKey: supplier, escrowRef: utxo.ref });
+
+    expect(result.txCborHex).toBe("live-cbor-sentinel");
+    expect(result.expectedTxHash).toBe("live-hash-sentinel");
+    expect(liveCbor.buildLiveTxForRelease).toHaveBeenCalledTimes(1);
+  });
+
+  it("passes the escrow UTxO, decoded datum, and a real-clock tipMs to the live builder", async () => {
+    const chain = fakeLiveChain();
+    const supplier = buildSupplierWalletKey();
+    const utxo = buildSubmittedEscrowUtxo();
+    const before = Date.now();
+
+    await buildReleaseTx({ chain, supplierKey: supplier, escrowRef: utxo.ref });
+
+    const mockFn = liveCbor.buildLiveTxForRelease as unknown as ReturnType<typeof vi.fn>;
+    const args = mockFn.mock.calls.at(-1)?.[0] as Record<string, unknown>;
+    expect(args.escrowUtxo).toEqual(utxo);
+    expect((args.datum as { state: string }).state).toBe("Submitted");
+    expect(args.supplierKey).toBe(supplier);
+    // Live path derives tipMs from the real clock (reclaim.ts parity), not
+    // from the mock slot→ms mapping.
+    expect(args.tipMs as number).toBeGreaterThanOrEqual(before);
+  });
+});