The code behind Vantage, open for reading.

def make_state(self, secret_key: str) -> str:
    """Format: <nonce>~<unix_ts>.<HMAC-SHA256("<nonce>~<ts>", secret_key)>

    The timestamp is part of the signed payload, so it cannot be forged
    independently — verify_state() can therefore reject stale tokens."""
    nonce = secrets.token_urlsafe(24)
    payload = f"{nonce}~{int(time.time())}"
    mac = hmac.new(secret_key.encode(), payload.encode(), hashlib.sha256).hexdigest()
    return f"{payload}.{mac}"

def verify_state(self, state: str, secret_key: str, max_age_seconds: int | None = None) -> bool:
    try:
        payload, mac = state.rsplit(".", 1)
        expected = hmac.new(secret_key.encode(), payload.encode(), hashlib.sha256).hexdigest()
        if not hmac.compare_digest(expected, mac):          # constant-time compare
            return False
        if max_age_seconds is not None:
            if "~" not in payload:                          # reject legacy tokens w/o a timestamp
                return False
            _nonce, ts_str = payload.rsplit("~", 1)
            if time.time() - int(ts_str) > max_age_seconds:  # reject stale/replayed tokens
                return False
        return True
    except Exception:
        return False

mine = {"pid": os.getpid(), "name": func.__name__}
acquired = bool(cache.add(_LOCK_KEY, mine, expire=_LOCK_TTL_S))   # atomic: writes only if absent
if not acquired:
    # Slot busy — but is the holder still alive? A holder that died without
    # releasing (OOM/SIGKILL) must not wedge the slot; reclaim it.
    holder = cache.get(_LOCK_KEY) or {}
    hpid = holder.get("pid") if isinstance(holder, dict) else None
    if hpid is not None and not _pid_alive(hpid):
        cache.set(_LOCK_KEY, mine, expire=_LOCK_TTL_S)
        acquired = True

SELECT
    vpp.issuer_id                                                 AS issuer_id,
    vpp.service_area_external_id                                  AS service_area_external_id,
    mbs.audience                                                  AS audience,
    array_agg(DISTINCT concat(zc.fips_code, '|', zc.county_name)) AS counties,
    array_agg(DISTINCT zc.zip_code)                              AS zips,
    array_agg(DISTINCT zc.state_code)                            AS states,
    array_agg(DISTINCT mbs.hios_id)                             AS hios_ids
-- … joins …
GROUP BY vpp.issuer_id, vpp.service_area_external_id, mbs.audience

def apply_event(agg: dict, ev: dict) -> None:
    """Fold one approval event into ``agg`` in place. Blank-fills are tallied but not counted."""
    if is_blank_fill(ev):
        agg["excluded_blank_fills"] = int(agg.get("excluded_blank_fills", 0)) + 1
        return

    agg["counted"] = int(agg.get("counted", 0)) + 1
    hios = str(ev.get("hios_id") or "").strip()
    if hios:
        agg["plans"][hios] = agg["plans"].get(hios, 0) + 1
        if iss := issuer_prefix(hios):
            agg["by_carrier"][iss] = agg["by_carrier"].get(iss, 0) + 1
    if fld := str(ev.get("field") or "").strip():
        agg["by_field"][fld] = agg["by_field"].get(fld, 0) + 1
    # … by_approver, by_day, per-run rollups …

def uhc_post_effective_date(quarter, year=None, today=None) -> str:
    """The requestEffectiveDate to send UHC — a date the API will accept.

    UHC rejects a past effective date, so a past quarter is bumped to the earliest 1st/15th of a
    month still inside the quarter that hasn't passed yet; a current/future quarter is unchanged."""
    eff = uhc_quarter_effective_date(quarter, year)
    if not eff:
        return ""
    today_iso = (today or date.today()).isoformat()
    if eff >= today_iso:                      # current/future quarter -> unchanged
        return eff
    y = str(year) if year is not None else PLAN_YEAR
    candidates = [f"{y}-{mm}-{dd}" for mm in _UHC_QUARTER_MONTHS.get(quarter, ()) for dd in ("01", "15")]
    for cand in candidates:                   # earliest in-quarter 1st/15th that hasn't passed
        if cand >= today_iso:
            return cand
    return eff                                # quarter fully past -> best-effort true start

def execute_athena_query(
    query: str,
    timeout_minutes: int | None = 5,
    progress_callback: Callable[[], None] | None = None,
    max_rows: int | None = None,          # abort the fetch if the result exceeds this many rows
) -> pd.DataFrame:
    tagged_query = f"{_BW_TAG}\n{query}"  # /* source=vantage-bw */ — CloudWatch cost attribution
    athena_client = boto3.client(
        "athena",
        config=BotocoreConfig(connect_timeout=900, read_timeout=900, retries={"max_attempts": 3}),
    )
    # … start_query_execution(WorkGroup=…), poll to completion honoring timeout_seconds …