Caffeine Decay

{
  "asOf": "2026-10-12T01:41:12.828Z",
  "bedtimeClock": "10:00 PM",
  "belowThresholdAt": "5:00 AM",
  "belowThresholdDayOffset": 1,
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "doseMg": 200,
  "doseTimeClock": "2:00 PM",
  "halfLifeHours": 5,
  "halfLifeTable": [
    {
      "halfLives": 0,
      "hours": 0,
      "remainingMg": 200
    },
    {
      "halfLives": 1,
      "hours": 5,
      "remainingMg": 100
    }
  ],
  "hoursElapsed": 10,
  "hoursFromDoseToBedtime": 8,
  "hoursUntilBelowThreshold": 15,
  "notChecked": [
    "your own caffeine half-life (genetics, pregnancy, medicines, smoking and liver health change it)",
    "the real caffeine content of any drink",
    "…2 more"
  ],
  "percentRemaining": 25,
  "reasons": [
    "Each half-life halves the amount; remaining = dose x 0.5^(hours / half-life).",
    "A bedtime earlier on the clock than the dose time is read as the next day."
  ],
  "remainingAtBedtimeMg": 65.98,
  "remainingMg": 50,
  "source": "computed locally (first-order decay: dose x 0.5^(hours / half-life))",
  "summary": "50 mg of 200 mg remains after 10 h (half-life 5 h); 15 h until below 25 mg. Below 25 mg at 5:00 AM (+1 day). At bedtime 10:00 PM (8 h later) about 66 mg remains.",
  "thresholdMg": 25,
  "verdict": "COMPUTED"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://focus-sleep-calc.x402tookit.com/caffeine-decay?bedtime=10%3A00+PM&doseMg=200&doseTime=2%3A00+PM&halfLifeHours=5&hoursElapsed=10&thresholdMg=25'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://focus-sleep-calc.x402tookit.com/caffeine-decay?bedtime=10%3A00+PM&doseMg=200&doseTime=2%3A00+PM&halfLifeHours=5&hoursElapsed=10&thresholdMg=25' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Ffocus-sleep-calc.x402tookit.com%2Fcaffeine-decay
const res = await pay("https://focus-sleep-calc.x402tookit.com/caffeine-decay?bedtime=10%3A00+PM&doseMg=200&doseTime=2%3A00+PM&halfLifeHours=5&hoursElapsed=10&thresholdMg=25");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://focus-sleep-calc.x402tookit.com/caffeine-decay?bedtime=10%3A00+PM&doseMg=200&doseTime=2%3A00+PM&halfLifeHours=5&hoursElapsed=10&thresholdMg=25")
    print(res.status_code, res.text)