Python でプロジェクト別の API 支出を追跡し、予算アラートを受け取る

import json, os, time
from openai import OpenAI

client = OpenAI(base_url="https://api.cheaptokens.dev/v1",
                api_key=os.environ["CHEAPTOKENS_API_KEY"])

def ask(project, model, messages):
    r = client.chat.completions.create(model=model, messages=messages)
    with open(time.strftime("usage-%Y-%m.jsonl"), "a") as f:
        f.write(json.dumps({"project": project, "model": model,
                            "prompt_tokens": r.usage.prompt_tokens,
                            "completion_tokens": r.usage.completion_tokens}) + "\n")
    return r

ask("support-bot", "zai-org/GLM-5.3-Flash",
    [{"role": "user", "content": "Where is my order?"}])

import json, os, sys, time
from collections import defaultdict

LOG = time.strftime("usage-%Y-%m.jsonl")
BUDGET = float(os.environ.get("BUDGET_USD", "10"))  # example, substitute your own
STATE = LOG + ".alert"
LEVELS = [50, 75, 95, 100]
PRICES = {  # USD per 1M tokens (input, output): example, substitute current prices
    "deepseek-ai/DeepSeek-V4-Flash-0731": (1.0, 2.0),
    "zai-org/GLM-5.3-Flash": (1.0, 2.0),
}

spend = defaultdict(float)
with open(LOG) as f:
    for line in f:
        r = json.loads(line)
        p_in, p_out = PRICES[r["model"]]
        spend[r["project"]] += (r["prompt_tokens"] * p_in
                                + r["completion_tokens"] * p_out) / 1_000_000

total = sum(spend.values())
if total == 0:
    sys.exit("log is empty")

for name, usd in sorted(spend.items(), key=lambda kv: -kv[1]):
    print(f"{name:<8} ${usd:6.2f} {usd / total:5.0%}")
print(f"{'total':<8} ${total:6.2f} of ${BUDGET:.2f} ({total / BUDGET:.0%})")

last = int(open(STATE).read()) if os.path.exists(STATE) else 0
crossed = [l for l in LEVELS if total >= BUDGET * l / 100 and l > last]
if crossed:
    print(f"WARNING: budget passed {crossed[-1]}%")
    open(STATE, "w").write(str(crossed[-1]))

{"project": "agent", "model": "deepseek-ai/DeepSeek-V4-Flash-0731", "prompt_tokens": 2400000, "completion_tokens": 300000}
{"project": "agent", "model": "deepseek-ai/DeepSeek-V4-Flash-0731", "prompt_tokens": 1000000, "completion_tokens": 100000}
{"project": "blog", "model": "zai-org/GLM-5.3-Flash", "prompt_tokens": 800000, "completion_tokens": 400000}
{"project": "bot", "model": "zai-org/GLM-5.3-Flash", "prompt_tokens": 500000, "completion_tokens": 100000}

agent    $  4.20   65%
blog     $  1.60   25%
bot      $  0.70   11%
total    $  6.50 of $10.00 (65%)
WARNING: budget passed 50%