test: add fast-check property tests for Stellar scalar arithmetic

.github/workflows/ci.yml

@@ -4,6 +4,8 @@ on:
     branches: [main]
   pull_request:
     branches: [main]
+  schedule:
+    - cron: '0 2 * * *'
 jobs:
   test:
     runs-on: ubuntu-latest
@@ -20,3 +22,19 @@ jobs:
       - run: pnpm run format:check
       - run: pnpm build
       - run: pnpm test
+
+  slow-tests:
+    name: Property fuzz (nightly)
+    runs-on: ubuntu-latest
+    if: github.event_name == 'schedule'
+    steps:
+      - uses: actions/checkout@v4
+      - uses: pnpm/action-setup@v4
+        with:
+          version: 10
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+      - run: pnpm install --frozen-lockfile
+      - run: pnpm test:fuzz

README.md

@@ -265,6 +265,31 @@ const metaAddress = metaAddressFromNameData(cellData);
 // => "st:ckb:..."
 ```
 
+## Property tests
+
+The Stellar scalar module is covered by [fast-check](https://fast-check.dev/) property tests in `test/chains/stellar/properties.test.ts`. These go beyond fixed unit tests by generating thousands of random inputs and asserting mathematical invariants:
+
+| Property                    | What it checks                                                                        |
+| --------------------------- | ------------------------------------------------------------------------------------- |
+| Addition associativity      | `(a+b)+c == a+(b+c) mod L` for all scalars                                            |
+| Addition commutativity      | `a+b == b+a mod L`                                                                    |
+| Additive identity           | `a+0 == a mod L`                                                                      |
+| Reduction stability         | `bytesToScalar(scalarToBytes(a)) == a` round-trips losslessly                         |
+| `seedToScalar` determinism  | same seed → same scalar; distinct seeds → distinct scalars                            |
+| Stealth equation            | `(m + s_h)*G == m*G + s_h*G` — the homomorphism that makes stealth spending work      |
+| View-tag uniformity         | chi-square test over 10k inputs confirms `computeViewTag` output is uniform `[0,255]` |
+| `signWithScalar` round-trip | every `(scalar, message)` pair produces a verifiable ed25519 signature                |
+
+```bash
+# Standard run — 1 000 cases per property
+pnpm test
+
+# Thorough fuzz run — 100 000 cases per property
+pnpm test:fuzz
+```
+
+The nightly CI job (`slow-tests`) runs `pnpm test:fuzz` automatically at 02:00 UTC.
+
 ## Documentation
 
 Full protocol documentation, architecture details, and integration guides are available at [wraith-protocol/docs](https://github.com/wraith-protocol/docs).

package.json

@@ -39,16 +39,17 @@
     "clean": "rm -rf dist",
     "format": "prettier --write .",
     "format:check": "prettier --check .",
-    "prepare": "husky"
+    "prepare": "husky",
+    "test:fuzz": "FC_RUNS=100000 vitest run test/chains/stellar/properties.test.ts"
   },
   "dependencies": {
     "@noble/curves": "^1.8.0",
     "@noble/hashes": "^1.7.0",
     "viem": "^2.23.0"
   },
   "peerDependencies": {
-    "@stellar/stellar-sdk": "^13.1.0",
-    "@solana/web3.js": "^1.95.0"
+    "@solana/web3.js": "^1.95.0",
+    "@stellar/stellar-sdk": "^13.1.0"
   },
   "peerDependenciesMeta": {
     "@stellar/stellar-sdk": {
@@ -63,6 +64,7 @@
     "@commitlint/config-conventional": "^19.6.0",
     "@solana/web3.js": "^1.98.4",
     "@stellar/stellar-sdk": "^13.1.0",
+    "fast-check": "^4.8.0",
     "husky": "^9.1.0",
     "prettier": "^3.4.0",
     "tsup": "^8.4.0",