diff --git a/README.md b/README.md
index 5af295d..98831af 100644
--- a/README.md
+++ b/README.md
@@ -72,7 +72,7 @@ Current coverage notes:
 - `LiteSVM` migration-flow suite covers `67` end-to-end cases
 - `Mollusk` lane covers `11` SBF-backed regression and fixture-replay cases
 - `Kani` lane covers `16` proof harnesses
-- SDK test suite covers `29` release and validator checks
+- SDK test suite covers `32` release and validator checks
 - `run-local-assurance-lane.sh` requires a clean worktree by default; verified-build is part of the release-grade path
 
 Important toolchain note:
diff --git a/sdk/package.json b/sdk/package.json
index 18d0b4f..b1b9dd9 100644
--- a/sdk/package.json
+++ b/sdk/package.json
@@ -4,6 +4,9 @@
   "private": true,
   "author": "Quantu Labs",
   "license": "MIT",
+  "engines": {
+    "node": ">=22"
+  },
   "type": "module",
   "main": "./src/index.ts",
   "types": "./src/index.ts",
diff --git a/sdk/src/index.test.ts b/sdk/src/index.test.ts
new file mode 100644
index 0000000..6aec245
--- /dev/null
+++ b/sdk/src/index.test.ts
@@ -0,0 +1,97 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { PublicKey } from "@solana/web3.js";
+
+import {
+  MIGRATION_CONFIG_DISCRIMINATOR,
+  MIGRATION_CONFIG_SIZE,
+  MIGRATION_CONFIG_VERSION,
+  TOKEN_PROGRAM_ID,
+  decodeMigrationConfig,
+  encodeInitializeConfigData,
+  encodeMigrateExactData,
+  encodeSetPauseData,
+  encodeWithdrawUnclaimedData,
+} from "./index.ts";
+
+test("instruction payloads use stable opcodes and little-endian scalars", () => {
+  const init = encodeInitializeConfigData(100n, 200n, 42n);
+  assert.equal(init[0], 0);
+  assert.equal(init.readBigInt64LE(1), 100n);
+  assert.equal(init.readBigInt64LE(9), 200n);
+  assert.equal(init.readBigUInt64LE(17), 42n);
+
+  assert.deepEqual(encodeSetPauseData(true), Buffer.from([1, 1]));
+  assert.deepEqual(encodeSetPauseData(false), Buffer.from([1, 0]));
+
+  const migrate = encodeMigrateExactData(999n);
+  assert.equal(migrate[0], 2);
+  assert.equal(migrate.readBigUInt64LE(1), 999n);
+
+  assert.deepEqual(encodeWithdrawUnclaimedData(), Buffer.from([3]));
+});
+
+test("decodeMigrationConfig rejects wrong size, discriminator, and version", () => {
+  assert.throws(
+    () => decodeMigrationConfig(Buffer.alloc(MIGRATION_CONFIG_SIZE - 1)),
+    /exactly 296 bytes/,
+  );
+  const wrongDisc = Buffer.alloc(MIGRATION_CONFIG_SIZE);
+  assert.throws(() => decodeMigrationConfig(wrongDisc), /discriminator/);
+
+  const wrongVer = Buffer.alloc(MIGRATION_CONFIG_SIZE);
+  MIGRATION_CONFIG_DISCRIMINATOR.copy(wrongVer, 0);
+  wrongVer[8] = 99;
+  assert.throws(() => decodeMigrationConfig(wrongVer), /Unsupported MigrationConfig version/);
+});
+
+test("decodeMigrationConfig reads on-chain layout including padding before total_migrated", () => {
+  const data = Buffer.alloc(MIGRATION_CONFIG_SIZE);
+  MIGRATION_CONFIG_DISCRIMINATOR.copy(data, 0);
+  data[8] = MIGRATION_CONFIG_VERSION;
+  data[9] = 7;
+  data[10] = 8;
+  data[11] = 1;
+
+  const admin = Buffer.alloc(32, 0x01);
+  const sourceMint = Buffer.alloc(32, 0x02);
+  const destMint = Buffer.alloc(32, 0x03);
+  const tokenProg = TOKEN_PROGRAM_ID.toBuffer();
+  const vaultAuth = Buffer.alloc(32, 0x04);
+  const reserve = Buffer.alloc(32, 0x05);
+
+  admin.copy(data, 12);
+  sourceMint.copy(data, 44);
+  destMint.copy(data, 76);
+  tokenProg.copy(data, 108);
+  vaultAuth.copy(data, 140);
+  reserve.copy(data, 172);
+
+  data.writeBigUInt64LE(12345n, 208);
+  data.writeBigInt64LE(1_700_000_000n, 216);
+  data.writeBigInt64LE(1_800_000_000n, 224);
+
+  data.writeBigUInt64LE(1_000_000n, 232);
+  const refund = PublicKey.unique();
+  refund.toBuffer().copy(data, 240);
+  data[272] = 1;
+
+  const parsed = decodeMigrationConfig(data);
+
+  assert.equal(parsed.version, MIGRATION_CONFIG_VERSION);
+  assert.equal(parsed.bump, 7);
+  assert.equal(parsed.vaultAuthorityBump, 8);
+  assert.equal(parsed.paused, true);
+  assert.ok(parsed.admin.equals(new PublicKey(admin)));
+  assert.ok(parsed.sourceMint.equals(new PublicKey(sourceMint)));
+  assert.ok(parsed.destinationMint.equals(new PublicKey(destMint)));
+  assert.ok(parsed.tokenProgramId.equals(TOKEN_PROGRAM_ID));
+  assert.ok(parsed.vaultAuthority.equals(new PublicKey(vaultAuth)));
+  assert.ok(parsed.reserveVault.equals(new PublicKey(reserve)));
+  assert.equal(parsed.totalMigrated, 12345n);
+  assert.equal(parsed.startTs, 1_700_000_000n);
+  assert.equal(parsed.endTs, 1_800_000_000n);
+  assert.equal(parsed.migrationCap, 1_000_000n);
+  assert.ok(parsed.refundRecipient.equals(refund));
+  assert.equal(parsed.unclaimedWithdrawn, true);
+});