diff --git a/TODO.md b/TODO.md
index 3d8835c..efebb95 100644
--- a/TODO.md
+++ b/TODO.md
@@ -116,7 +116,8 @@ untouched and the helpers are optional and swappable. This is the sibling of §2
 
 ## 3. Testing
 
-- [ ] `P1` Add JS integration tests for the script/Plutus paths — these are implemented in `wrappers/js/src/index.js` but have **zero** test coverage: `ScriptTxBuilder` validators + redeemers, `collectFromScript`, `mintPlutusAssets`, `readFrom` (reference inputs), and compose-with-`ScriptTx`. Python's `tests/` are the reference for what to assert.
+- [x] `P1` ~~Add JS integration tests for the script/Plutus paths.~~ **Done (and the item's premise was superseded by the TxPlan refactor):** the old fluent `ScriptTxBuilder` / `collectFromScript` / `mintPlutusAssets` / `readFrom` API was deleted — script/Plutus paths are now TxPlan YAML fixtures, covered at the build level in `test/intents.e2e.test.js`: all 20 top-level intents (incl. `reference_input`, `compose`, `native_script`) plus the three `plutus/` fixtures — **mint**, **spend**, and **lock** — each asserting non-empty CBOR + 64-char hash + positive fee, that mint/spend **require** caller-supplied exec units (build throws without them), and that `plutus.dataHash` reproduces the lock fixture's datum hash. Node-level (DevKit): a Plutus-mint **build → sign → submit → assert the minted asset landed on-chain** round-trip in `test/quicktx.integration.test.js`, mirroring Go's `TestIntegrationPlutusMint`.
+- [ ] `P1` **Fix JS cost-model key ordering for Plutus builds.** Surfaced while adding the JS Plutus-mint submit test: passing the cost models fetched from a Blockfrost-style provider (`/epochs/parameters` returns them as a map keyed by zero-padded indices `"000".."165"`) into a Plutus `build()` yields a tx the node rejects with `PPViewHashesDontMatch` — JS's JSON parse reorders the non-padded integer-like keys (`"100".."165"`) ahead of the padded ones, scrambling the cost-model order vs the ledger's canonical order and corrupting the script-integrity hash. (Go's `json.Marshal` sorts keys lexicographically, which for zero-padded keys equals numeric order, so the Go path is unaffected.) The integration test works around it by dropping the fetched cost models so the lib uses its built-in standard set; the real fix is to preserve canonical cost-model order in the JS wrapper before handing params to the native lib. Likely affects the §2c provider helpers, which will fetch and pass these params.
 - [ ] `P1` Raise Go and Rust test breadth toward Python's (~100 cases vs ~61); port Python's per-module unit tests.
 - [ ] `P1` Add a cross-wrapper parity test matrix asserting every `@CEntryPoint` is exercised in every language.
 - [ ] `P2` Run the Yaci DevKit integration tests in CI (containerized DevKit) instead of skip-if-not-running.
diff --git a/wrappers/js/test/intents.e2e.test.js b/wrappers/js/test/intents.e2e.test.js
index 02fe77c..4ccdf5d 100644
--- a/wrappers/js/test/intents.e2e.test.js
+++ b/wrappers/js/test/intents.e2e.test.js
@@ -40,6 +40,14 @@ function utxos() {
   ];
 }
 
+// A successfully built tx: non-empty CBOR, a 64-char hash, and a positive fee. Mirrors the Python
+// reference's _assert_built so the wrappers assert the same shape.
+function assertBuilt(result) {
+  expect(result.tx_cbor.length).toBeGreaterThan(0);
+  expect(result.tx_hash.length).toBe(64);
+  expect(Number(result.fee)).toBeGreaterThan(0);
+}
+
 describe("QuickTx intents E2E", () => {
   let bridge;
   beforeAll(() => { bridge = new CclBridge(); });
@@ -50,19 +58,18 @@ describe("QuickTx intents E2E", () => {
   for (const f of fixtures) {
     it(`builds ${f.replace(".yaml", "")}`, () => {
       const yaml = readFileSync(join(FIXTURES, f), "utf8");
-      const result = bridge.quicktx.build(yaml, utxos(), PROTOCOL_PARAMS);
-      expect(result.tx_cbor.length).toBeGreaterThan(0);
-      expect(result.tx_hash.length).toBe(64);
-      expect(Number(result.fee)).toBeGreaterThan(0);
+      assertBuilt(bridge.quicktx.build(yaml, utxos(), PROTOCOL_PARAMS));
     });
   }
 
+  // --- Plutus / script paths (the plutus/ sub-directory, not covered by the top-level loop) ---
+
   it("builds a Plutus mint with execution units", () => {
     const yaml = readFileSync(join(FIXTURES, "plutus", "script_minting.yaml"), "utf8");
     const u = [{ tx_hash: "a".repeat(64), output_index: 0, address: SENDER,
                  amount: [{ unit: "lovelace", quantity: "2000000000" }] }];
-    const result = bridge.quicktx.build(yaml, u, PROTOCOL_PARAMS, EXEC_UNITS);
-    expect(result.tx_hash.length).toBe(64);
+    assertBuilt(bridge.quicktx.build(yaml, u, PROTOCOL_PARAMS, EXEC_UNITS));
+    // The Plutus path requires caller-supplied exec units; without them the build is rejected.
     expect(() => bridge.quicktx.build(yaml, u, PROTOCOL_PARAMS)).toThrow();
   });
 
@@ -74,8 +81,21 @@ describe("QuickTx intents E2E", () => {
       { tx_hash: "a".repeat(64), output_index: 0, address: SENDER,
         amount: [{ unit: "lovelace", quantity: "2000000000" }] },
     ];
-    const result = bridge.quicktx.build(yaml, u, PROTOCOL_PARAMS, EXEC_UNITS);
-    expect(result.tx_hash.length).toBe(64);
+    assertBuilt(bridge.quicktx.build(yaml, u, PROTOCOL_PARAMS, EXEC_UNITS));
     expect(() => bridge.quicktx.build(yaml, u, PROTOCOL_PARAMS)).toThrow();
   });
+
+  it("builds a Plutus lock (pay to a script address with a datum hash)", () => {
+    // Locking funds at a script address is a plain payment carrying a datum hash — no script runs,
+    // so no exec units are required (unlike the spend that later unlocks it).
+    const yaml = readFileSync(join(FIXTURES, "plutus", "plutus_lock.yaml"), "utf8");
+    assertBuilt(bridge.quicktx.build(yaml, utxos(), PROTOCOL_PARAMS));
+  });
+
+  it("derives the datum hash the lock fixture commits to", () => {
+    // plutus_lock.yaml locks under datum_hash 9e1199… — the Plutus data hash of the integer 42
+    // (CBOR 182a). Assert the bridge computes the exact value the fixture embeds, tying the
+    // plutus.dataHash primitive to the on-fixture datum.
+    expect(bridge.plutus.dataHash("182a")).toBe(SCRIPT_DATUM_HASH);
+  });
 });
diff --git a/wrappers/js/test/quicktx.integration.test.js b/wrappers/js/test/quicktx.integration.test.js
index a112f82..3a7d5aa 100644
--- a/wrappers/js/test/quicktx.integration.test.js
+++ b/wrappers/js/test/quicktx.integration.test.js
@@ -11,9 +11,22 @@
 import { describe, it, expect, beforeAll, afterAll, setDefaultTimeout } from "bun:test";
 import { CclBridge, TESTNET } from "../src/index.js";
 import { DevKitHelper } from "./devkit-helper.js";
+import { readFileSync } from "fs";
+import { join, dirname } from "path";
+import { fileURLToPath } from "url";
 
 setDefaultTimeout(60_000);
 
+const FIXTURES = join(dirname(fileURLToPath(import.meta.url)), "../../../test-fixtures/quicktx-intents");
+
+// The fixed test account the quicktx-intents fixtures are derived from (account 0/0). A Plutus
+// fixture bakes this address in as the fee payer, so submitting it means funding and signing with
+// this exact account rather than a freshly-created one.
+const INTENT_MNEMONIC = "test walk nut penalty hip pave soap entry language right filter choice";
+const INTENT_SENDER = "addr_test1qz2fxv2umyhttkxyxp8x0dlpdt3k6cwng5pxj3jhsydzer3jcu5d8ps7zex2k2xt3uqxgjqnnj83ws8lhrn648jjxtwq2ytjqp";
+// The enterprise address the mint fixtures pay the freshly minted asset to.
+const MINT_RECEIVER = "addr_test1vz2fxv2umyhttkxyxp8x0dlpdt3k6cwng5pxj3jhsydzerspjrlsz";
+
 function paymentYaml(from, to, quantity) {
   return `
 version: 1.0
@@ -137,4 +150,48 @@ transaction:
     const yaml = paymentYaml(sender.base_address, receiver.base_address, "100000000");
     expect(() => bridge.quicktx.build(yaml, utxos, pp)).toThrow();
   });
+
+  // Plutus round-trip: build the script_minting fixture with caller-supplied exec units, sign with
+  // the fee payer's payment key, submit, and assert the minted asset landed on-chain. "Submit
+  // accepted" alone doesn't prove the script ran and minted — the receiver holding a non-lovelace
+  // asset does. Mirrors the Go TestIntegrationPlutusMint.
+  //
+  // We build WITHOUT the devnet's fetched cost models, so the native lib uses its built-in standard
+  // Conway cost models (which the devnet runs). Passing DevKit's fetched cost models instead is
+  // rejected with PPViewHashesDontMatch: /epochs/parameters returns them as a map keyed by
+  // zero-padded indices ("000".."165"), and JS's JSON parse reorders the non-padded integer-like
+  // keys ("100".."165") ahead of the padded ones, scrambling the cost-model order vs the ledger's
+  // canonical order and corrupting the script-integrity hash. Go's lexicographic map marshalling
+  // preserves the order, which is why its equivalent test passes with the fetched params. Threading
+  // fetched cost models through to Plutus builds needs an order-preserving fix in the wrapper —
+  // tracked as a follow-up in TODO.md §3.
+  it("should build, sign, and submit a Plutus mint", async () => {
+    if (skip) return;
+
+    await devkit.reset();
+    await devkit.waitForBlock(3000);
+    await devkit.topup(INTENT_SENDER, 6000);
+    await devkit.waitForBlock(3000);
+
+    const utxos = await devkit.getUtxos(INTENT_SENDER);
+    const pp = await devkit.getProtocolParams();
+    const yaml = readFileSync(join(FIXTURES, "plutus", "script_minting.yaml"), "utf8");
+
+    const ppForBuild = { ...pp };
+    for (const k of ["cost_models", "costModels", "cost_mdls", "costMdls"]) delete ppForBuild[k];
+
+    const result = bridge.quicktx.build(yaml, utxos, ppForBuild, [{ mem: 2000000, steps: 500000000 }]);
+    expect(result.tx_hash.length).toBe(64);
+
+    const signedTx = bridge.account.signTxWithKeys(INTENT_MNEMONIC, TESTNET, 0, 0, result.tx_cbor, ["payment"]);
+    // A successful submit returns the 64-char tx hash; a rejection returns an error body. Assert the
+    // hash so a failed Plutus validation surfaces here, not as a missing asset further down.
+    const submitResult = await devkit.submitTx(signedTx);
+    expect(submitResult).toMatch(/^[0-9a-f]{64}$/);
+
+    await devkit.waitForBlock(3000);
+    const receiverUtxos = await devkit.getUtxos(MINT_RECEIVER);
+    const hasMintedAsset = receiverUtxos.some((u) => u.amount.some((a) => a.unit !== "lovelace"));
+    expect(hasMintedAsset).toBe(true);
+  });
 });