# Validator parity probe — Rust :3100 vs Go :4110

**Date:** 2026-05-02T08:59:17Z
**Rust gateway:** `http://127.0.0.1:3100`  ·  **Go gateway:** `http://127.0.0.1:4110`

Identical `POST /v1/validate` request → both runtimes. Match
= identical HTTP status + identical body (modulo `elapsed_ms`).

| Case | Rust status | Go status | Status match | Body match |
|---|---:|---:|:---:|:---:|
| playbook_happy | 200 | 200 | ✓ | ✓ |
| playbook_missing_fingerprint | 422 | 422 | ✓ | ✗ |
| playbook_wrong_prefix | 422 | 422 | ✓ | ✗ |
| playbook_empty_endorsed | 422 | 422 | ✓ | ✗ |
| playbook_overfull | 422 | 422 | ✓ | ✗ |
| fill_phantom | 422 | 422 | ✓ | ✗ |

**Tally:** 1 match · 5 diff (out of 6 cases)

## Divergences

<details><summary>DIFF — `playbook_missing_fingerprint`</summary>

**Rust** (HTTP 422):
```json
{
  "Schema": {
    "field": "fingerprint",
    "reason": "missing — required for Phase 25 validity window"
  }
}
```

**Go** (HTTP 422):
```json
{
  "Field": "fingerprint",
  "Kind": "schema",
  "Reason": "missing — required for Phase 25 validity window"
}
```

</details>

<details><summary>DIFF — `playbook_wrong_prefix`</summary>

**Rust** (HTTP 422):
```json
{
  "Schema": {
    "field": "operation",
    "reason": "expected `fill: ...` prefix, got \"sms_draft: hello\""
  }
}
```

**Go** (HTTP 422):
```json
{
  "Field": "operation",
  "Kind": "schema",
  "Reason": "expected `fill: ...` prefix, got \"sms_draft: hello\""
}
```

</details>

<details><summary>DIFF — `playbook_empty_endorsed`</summary>

**Rust** (HTTP 422):
```json
{
  "Completeness": {
    "reason": "endorsed_names must be non-empty"
  }
}
```

**Go** (HTTP 422):
```json
{
  "Field": "",
  "Kind": "completeness",
  "Reason": "endorsed_names must be non-empty"
}
```

</details>

<details><summary>DIFF — `playbook_overfull`</summary>

**Rust** (HTTP 422):
```json
{
  "Completeness": {
    "reason": "endorsed_names (3) exceeds target_count × 2 (2)"
  }
}
```

**Go** (HTTP 422):
```json
{
  "Field": "",
  "Kind": "completeness",
  "Reason": "endorsed_names (3) exceeds target_count × 2 (2)"
}
```

</details>

<details><summary>DIFF — `fill_phantom`</summary>

**Rust** (HTTP 422):
```json
{
  "Consistency": {
    "reason": "fills[0].candidate_id \"W-PHANTOM-NEVER-EXISTS\" does not exist in worker roster"
  }
}
```

**Go** (HTTP 422):
```json
{
  "Field": "",
  "Kind": "consistency",
  "Reason": "fills[0].candidate_id \"W-PHANTOM-NEVER-EXISTS\" does not exist in worker roster"
}
```

</details>