VerifyGate — evidence record

AI proposes. Deterministic checks dispose. The evidence record proves it.

Repair report

spec: cart-total-tax-fix · mode: real · LLM adapter: nebius-token-factory

final verdict: PASS · repair rounds used: 1 / 3 · stopped: passed

LLM usage total: 2 call(s), 6390 total token(s)

Attempt 0 — FAIL

Hash chain verified at render time — this record is intact and tamper-evident.

Replay

python3 -m verifygate run --spec samples-js/spec.json --candidate samples-js/failing --mode real

spec hash: f9c36f2a2918c790004ce548874522d08990927bd12c4d1f0baa85d36539c1b7
candidate tree hash: b057a49e108268e29a5ce2f1e3984fdd9acff344cac55ca7ce1233d3ef79dfa7
record hash: 28963e7eafdbbe6f207767e8d4ace6aa8187707d2708be16edcf298e526b3bee
signature: 58efa4242f69fab99a0ade592074d62c…

Signed with the labelled public development key (demonstrates the mechanism; not production key management).

unit_tests FAIL

node --test

exit code: 1 · duration: 482 ms · timed out: False

stdout tail

✔ subtotal sums price * qty (1.1794ms)
✖ total applies the tax rate (6.020064ms)
✖ total rounds to cents (0.531748ms)
✔ total with zero tax equals the subtotal (0.35979ms)
ℹ tests 4
ℹ suites 0
ℹ pass 2
ℹ fail 2
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 209.752246

✖ failing tests:

test at cart.test.js:18:1
✖ total applies the tax rate (6.020064ms)
  AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:
  
  25.5 !== 30.6
  
      at TestContext.<anonymous> (/tmp/verifygate-reoopdez/cart.test.js:19:10)
      at Test.runInAsyncScope (node:async_hooks:227:14)
      at Test.run (node:internal/test_runner/test:1397:25)
      at Test.processPendingSubtests (node:internal/test_runner/test:969:18)
      at Test.postRun (node:internal/test_runner/test:1537:19)
      at Test.run (node:internal/test_runner/test:1462:12)
      at async startSubtestAfterBootstrap (node:internal/test_runner/harness:387:3) {
    generatedMessage: true,
    code: 'ERR_ASSERTION',
    actual: 25.5,
    expected: 30.6,
    operator: 'strictEqual',
    diff: 'simple'
  }

test at cart.test.js:22:1
✖ total rounds to cents (0.531748ms)
  AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:
  
  29.97 !== 32.07
  
      at TestContext.<anonymous> (/tmp/verifygate-reoopdez/cart.test.js:23:10)
      at Test.runInAsyncScope (node:async_hooks:227:14)
      at Test.run (node:internal/test_runner/test:1397:25)
      at Test.processPendingSubtests (node:internal/test_runner/test:969:18)
      at Test.postRun (node:internal/test_runner/test:1537:19)
      at Test.run (node:internal/test_runner/test:1462:12)
      at async Test.processPendingSubtests (node:internal/test_runner/test:969:7) {
    generatedMessage: true,
    code: 'ERR_ASSERTION',
    actual: 29.97,
    expected: 32.07,
    operator: 'strictEqual',
    diff: 'simple'
  }

entry hash: 18ba171dcb1574aa…

repro_script FAIL

node repro.js

exit code: 1 · duration: 118 ms · timed out: False

stderr tail

node:assert:152
  throw new AssertionError(obj);
  ^

AssertionError [ERR_ASSERTION]: cart repro failed: got 20

20 !== 24

    at Object.<anonymous> (/tmp/verifygate-reoopdez/repro.js:7:8)
    at Module._compile (node:internal/modules/cjs/loader:1929:14)
    at Object..js (node:internal/modules/cjs/loader:2060:10)
    at Module.load (node:internal/modules/cjs/loader:1651:32)
    at Module._load (node:internal/modules/cjs/loader:1443:12)
    at wrapModuleLoad (node:internal/modules/cjs/loader:261:19)
    at Module.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:154:5)
    at node:internal/main/run_main_module:33:47 {
  generatedMessage: false,
  code: 'ERR_ASSERTION',
  actual: 20,
  expected: 24,
  operator: 'strictEqual',
  diff: 'simple'
}

Node.js v24.20.0

entry hash: 646c09da5a6153d3…

Diagnosis commentary — never a verdict input


**Diagnosis**

| Check | What failed | Observed output | Expected |
|-------|-------------|-----------------|----------|
| `unit_tests` – *total applies the tax rate* | `total` returned **25.5** instead of **30.6** | 25.5 | 30.6 |
| `unit_tests` – *total rounds to cents* | `total` returned **29.97** instead of **32.07** | 29.97 | 32.07 |
| `repro_script` | `cart repro` returned **20** instead of **24** | 20 | 24 |

**Most likely cause**  
All three failures show the function that computes the cart total is returning the **subtotal only** – the tax component is missing.  
- In the first test, `25.5 × 1.20 = 30.6` (20 % tax).  
- In the second test, `29.97 × 1.07 ≈ 32.07` (≈7 % tax, matching the test’s tax rate).  
- In the repro script, `20 × 1.20 = 24` (again 20 % tax).

Thus the bug is likely a missing multiplication by `(1 + taxRate)` (or forgetting to convert a percentage tax rate to a decimal) inside the `total` calculation logic.

**Smallest next fix to try**  
Locate the function that calculates the cart total (probably in `cart.js` or a similar module) and ensure it applies the tax correctly, e.g.:

```javascript
// before (buggy)
function total(subtotal, taxRate) {
  return subtotal;          // ← tax omitted
}

// after (fixed)
function total(subtotal, taxRate) {
  // assuming taxRate is expressed as a percent (e.g., 20 for 20%)
  return subtotal * (1 + taxRate / 100);
}
```

Make the change, re‑run `node --test` and `node repro.js`. Both should now pass. If the tax rate is already stored as a decimal (0.20), simply use `subtotal * (1 + taxRate)`. After the fix, verify that the previously failing tests show a ✔️ and the repro script exits with code 0.

LLM adapter: nebius-token-factory · reference source: tavily

References unavailable: TAVILY_API_KEY is not set; references skipped (diagnosis proceeds without them) The verdict above does not depend on references.

LLM usage sealed in the hash chain

purpose	model	prompt	completion	total
explain_failure	nvidia/nemotron-3-super-120b-a12b	1296	1532	2828

Total tokens: 2828

Attempt 1 — PASS

Patch from previous attempt applied to: cart.js

Hash chain verified at render time — this record is intact and tamper-evident.

Replay

python3 -m verifygate replay --record samples-js/evidence_real_repair.json --spec samples-js/spec.json --candidate samples-js/failing --mode real # attempt 1: patched copy, reconstructed from the report's recorded patch

spec hash: f9c36f2a2918c790004ce548874522d08990927bd12c4d1f0baa85d36539c1b7
candidate tree hash: e13787416362ddb2a5f1a4ba6e662100b2da60e27ac014fe7c3b6b32254516fc
record hash: 51e0d72c66795709c7699d78aec6bb5558d6e80004cdd0408b559f2e5e6411f4
signature: 514563e74df596c8ace76ebebecb30c5…

Signed with the labelled public development key (demonstrates the mechanism; not production key management).

unit_tests PASS

node --test

exit code: 0 · duration: 315 ms · timed out: False

stdout tail

✔ subtotal sums price * qty (1.157177ms)
✔ total applies the tax rate (0.226189ms)
✔ total rounds to cents (0.150316ms)
✔ total with zero tax equals the subtotal (0.196214ms)
ℹ tests 4
ℹ suites 0
ℹ pass 4
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 114.462484

entry hash: 1024c22d39701b49…

repro_script PASS

node repro.js

exit code: 0 · duration: 64 ms · timed out: False

stdout tail

repro OK: 24

entry hash: 5037e37c86c2e9f7…

LLM usage sealed in the hash chain

purpose	model	prompt	completion	total
generate_patch	nvidia/nemotron-3-super-120b-a12b	2005	1557	3562

Total tokens: 3562