diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 727ec22..62bded4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -30,6 +30,10 @@ jobs:
       # test() bodies in this repo, so it cannot be trusted as a gate.
       - run: pnpm test:types
       - run: pnpm test
+      # Run a small fixed-seed sample of Stellar property tests on every PR
+      - name: Stellar property test sample
+        if: github.event_name == 'pull_request'
+        run: pnpm test:fuzz:sample
 
   entrypoints:
     name: Package entry point smoke tests
diff --git a/package.json b/package.json
index b3b896b..1ee548e 100644
--- a/package.json
+++ b/package.json
@@ -64,6 +64,8 @@
     "format:check": "prettier --check .",
     "prepare": "husky",
     "test:fuzz": "FC_RUNS=100000 vitest run test/chains/stellar/properties.test.ts",
+    "test:fuzz:sample": "FC_RUNS=100 FC_SEED=12345 vitest run test/chains/stellar/properties.test.ts",
+    "test:fuzz:proof": "FC_PROOF_TEST=1 vitest run test/chains/stellar/properties.test.ts",
     "test:leak": "node --expose-gc ./node_modules/vitest/vitest.mjs run test/leaks/scan-leak.test.ts --pool=threads",
     "test:heap-leak": "node --expose-gc ./node_modules/vitest/vitest.mjs run test/leaks/heap-snapshot.test.ts --pool=threads",
     "size": "size-limit",
diff --git a/test/chains/stellar/properties.test.ts b/test/chains/stellar/properties.test.ts
index 8299e8d..aff25eb 100644
--- a/test/chains/stellar/properties.test.ts
+++ b/test/chains/stellar/properties.test.ts
@@ -14,6 +14,38 @@ import {
 import { computeViewTag } from '../../../src/chains/stellar/stealth';
 
 const FC_RUNS = process.env.FC_RUNS ? parseInt(process.env.FC_RUNS, 10) : 1000;
+const FC_SEED = process.env.FC_SEED ? parseInt(process.env.FC_SEED, 10) : undefined;
+const FC_PATH = process.env.FC_PATH;
+
+// Configure fast-check with seed if provided
+const configure = () => {
+  if (FC_SEED !== undefined) {
+    console.log(`\n🔬 Using fixed seed: ${FC_SEED}`);
+    console.log(
+      `   Replay with: FC_SEED=${FC_SEED} FC_RUNS=${FC_RUNS} pnpm test test/chains/stellar/properties.test.ts\n`,
+    );
+    const config: Record<string, unknown> = { seed: FC_SEED };
+    if (FC_PATH !== undefined) {
+      config.path = FC_PATH;
+    }
+    return config;
+  }
+  return {};
+};
+
+// Custom reporter to print seed and path on failure
+const reporter = (runDetails: fc.RunDetails<unknown>) => {
+  if (runDetails.failed) {
+    const seed = runDetails.seed;
+    const path = runDetails.counterexamplePath;
+    console.error(`\n❌ Property test failed`);
+    console.error(`   Seed: ${seed}`);
+    console.error(`   Path: ${path}`);
+    const replayCmd = `FC_SEED=${seed} FC_PATH=${path} FC_RUNS=${FC_RUNS} pnpm test test/chains/stellar/properties.test.ts`;
+    console.error(`   Replay with: ${replayCmd}\n`);
+    throw new Error(fc.defaultReportMessage(runDetails));
+  }
+};
 
 // ─────────────────────────────────────────────────────────────
 // Helpers
@@ -48,7 +80,7 @@ describe('scalar algebra sanity', () => {
         const r2 = (b + a) % L;
         expect(r1).toBe(r2);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 
@@ -57,7 +89,7 @@ describe('scalar algebra sanity', () => {
       fc.property(scalarAnyArb, (a) => {
         expect((a + 0n) % L).toBe(a % L);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 });
@@ -73,7 +105,7 @@ describe('scalar encoding roundtrip', () => {
         const normalized = a % L;
         expect(bytesToScalar(scalarToBytes(normalized)) % L).toBe(normalized);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 
@@ -82,7 +114,7 @@ describe('scalar encoding roundtrip', () => {
       fc.property(scalarAnyArb, (a) => {
         expect(scalarToBytes(a)).toHaveLength(32);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 });
@@ -99,7 +131,7 @@ describe('seedToScalar stability', () => {
         const b = seedToScalar(seed);
         expect(a).toBe(b);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 
@@ -116,7 +148,7 @@ describe('seedToScalar stability', () => {
         // sanity: still a valid scalar space
         expect(s < 2n ** 256n).toBe(true);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 });
@@ -140,7 +172,7 @@ describe('stealth pubkey correctness', () => {
 
         expect(lhs.equals(rhs)).toBe(true);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 
@@ -159,7 +191,7 @@ describe('stealth pubkey correctness', () => {
 
         expect(derived).toEqual(expected);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 });
@@ -175,7 +207,7 @@ describe('view tag distribution sanity', () => {
         const tag = computeViewTag(secret);
         expect(tag >= 0 && tag <= 255).toBe(true);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 });
@@ -195,7 +227,7 @@ describe('signWithScalar correctness', () => {
         expect(sig).toHaveLength(64);
         expect(verifySignature(sig, msg, pub)).toBe(true);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 
@@ -210,7 +242,7 @@ describe('signWithScalar correctness', () => {
 
         expect(verifySignature(sig, m2, pub)).toBe(false);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 
@@ -227,7 +259,25 @@ describe('signWithScalar correctness', () => {
 
         expect(verifySignature(sig, msg, pub2)).toBe(false);
       }),
-      { numRuns: FC_RUNS },
+      { numRuns: FC_RUNS, ...configure(), reporter },
     );
   });
 });
+
+// ─────────────────────────────────────────────────────────────
+// 7. proof test: demonstrates replay output on failure
+// ─────────────────────────────────────────────────────────────
+
+if (process.env.FC_PROOF_TEST === '1') {
+  describe('replay output proof test', () => {
+    test('deliberately fails to prove replay output is emitted', () => {
+      fc.assert(
+        fc.property(scalarArb, (a: bigint) => {
+          // This will always fail
+          expect(a).toBe(0n);
+        }),
+        { numRuns: 10, seed: 42, reporter },
+      );
+    });
+  });
+}
diff --git a/vitest.config.ts b/vitest.config.ts
index 7e7bc32..a374b9c 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -31,7 +31,7 @@ export default defineConfig({
       'test/chains/evm/vectors.test.ts',
       'test/chains/solana/vectors.test.ts',
     ],
-    testTimeout: 1200000, // 20 minutes for high-run nightly fuzz tests
+    testTimeout: 3600000, // 60 minutes for high-run nightly fuzz tests (100k runs takes ~6.5min + reporting overhead)
   },
   benchmark: {
     include: ['test/chains/**/bench/**/*.bench.ts', 'test/bench/**/*.bench.ts'],