African government auctions, as JSON

• History calls (/tbills/{market}, /bonds/{market} and the CSV files under /api/data/) return rows dated in the latest 12 months, by auction or settlement date, up to 100 a call. Nothing is cut silently: whenever a key would have returned more, the response says "truncated": true with an upgrade link. It also carries a free_tier note, with free_tier.next for the next page inside the free window, and every keyless response has the header X-Afronomics-Free-Tier: true. CSV files say the same in the # lines at the top.
• Send a key as Authorization: Bearer afk_… (or X-API-Key: afk_…) for the full history and up to 5,000 rows a call; a CSV file with a key is the whole file. Keyed calls are served fresh and counted per key.
• In a browser, where a link cannot send a header, sign in once at /downloads with your key: for 12 hours the site's CSV links give the full history, counted against the key. The key never goes into a link. Analyst keys work for CSV files only, not the JSON API.
• A key that is unknown, revoked or expired is not an error: the call gets the free tier, with "key_status": "not_recognised" and the header X-Afronomics-Key: not-recognised.

Team and API and Enterprise licences can receive an auction.published event at an https address of their choice, once per market, tenor and auction date, within minutes of the result reaching the site. Ask the desk to set it up; you receive a signing secret. Every request carries X-Afronomics-Signature: t=<unix seconds>,v1=<hex>, the HMAC-SHA256 of <t>.<body> with your secret. Reject a timestamp more than five minutes old, and answer 2xx within ten seconds; anything else is retried on the next run for up to four days.

import hashlib, hmac, time

def verify(secret: str, header: str, body: bytes) -> bool:
    parts = dict(p.split("=", 1) for p in header.split(","))
    t = int(parts["t"])
    if abs(time.time() - t) > 300:
        return False
    want = hmac.new(secret.encode(), f"{t}.".encode() + body, hashlib.sha256).hexdigest()
    return hmac.compare_digest(want, parts["v1"])

# Body: {"id": "kenya:tbill:91:2026-10-26", "type": "auction.published", "market": "kenya",
#  "instrument": "tbill", "tenor_days": 91, "value_date": "2026-10-26", "rate_pct": 8.7478,
#  "offered_m": 8000, "received_m": 14336.6, "accepted_m": 14334.2, "source_url": "https://..."}