日次AI動画のコスト計算：30日間のAPI予算ガイド

ceil(0.016625 $ × 5 秒 × 1,000 クレジット/ドル)
= ceil(83.125 クレジット)
= 84 クレジット
= $0.084

30 日 × 84 クレジット = 2,520 クレジット = $2.52

月間生成コスト
= 日数 × 1 日あたりのビデオ × 受け入れられたビデオあたりの完了試行 × 試行あたりのコスト

export REAPI_API_KEY='replace-with-your-server-side-key'

curl --fail-with-body --silent --show-error \
  --request POST 'https://reapi.ai/api/v1/videos/generations' \
  --header "Authorization: Bearer $REAPI_API_KEY" \
  --header 'Content-Type: application/json' \
  --data '{
    "model": "seedance-2.0-mini",
    "prompt": "A handmade ceramic cup beside an open notebook, soft morning window light, one slow push-in shot, natural motion, no text",
    "resolution": "480p",
    "aspect_ratio": "9:16",
    "duration": 5,
    "generate_audio": false,
    "watermark": false
  }' \
  --output submit.json

TASK_ID="$(jq -r '.id' submit.json)"
test -n "$TASK_ID" && test "$TASK_ID" != 'null' || exit 1
printf '%s\n' "$TASK_ID" > task-id.txt

curl --fail-with-body --silent --show-error \
  --header "Authorization: Bearer $REAPI_API_KEY" \
  "https://reapi.ai/api/v1/tasks/$TASK_ID" \
  --output task.json
jq '{id, status, usage, output, error}' task.json

import { mkdir, readFile, rename, writeFile } from 'node:fs/promises';
import { join } from 'node:path';

const API_BASE = 'https://reapi.ai/api/v1';
const STORE_PATH = './daily-video-jobs.json';
const OUTPUT_DIR = './daily-video-output';
const POLL_MS = 5_000;
const POLL_LIMIT_MS = 30 * 60 * 1_000;
const POST_TIMEOUT_MS = 30_000;
const GET_TIMEOUT_MS = 20_000;
const DOWNLOAD_TIMEOUT_MS = 120_000;
const apiKey = process.env.REAPI_API_KEY;

if (!apiKey) {
  throw new Error('Set REAPI_API_KEY in the server environment.');
}

const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));

function retryAfterMs(value) {
  if (!value) return POLL_MS;
  const seconds = Number(value);
  if (Number.isFinite(seconds)) return Math.max(seconds * 1_000, 0);
  const date = Date.parse(value);
  return Number.isNaN(date) ? POLL_MS : Math.max(date - Date.now(), 0);
}

async function loadJobs() {
  try {
    return JSON.parse(await readFile(STORE_PATH, 'utf8'));
  } catch (error) {
    if (error.code === 'ENOENT') return {};
    throw error;
  }
}

async function saveJobs(jobs) {
  const temporaryPath = `${STORE_PATH}.tmp`;
  await writeFile(temporaryPath, `${JSON.stringify(jobs, null, 2)}\n`);
  await rename(temporaryPath, STORE_PATH);
}

async function requestJson(url, options) {
  const response = await fetch(url, options);
  const body = await response.text();
  let data;

  try {
    data = JSON.parse(body);
  } catch {
    data = { raw: body };
  }

  if (!response.ok) {
    const error = new Error(`HTTP ${response.status}: ${body.slice(0, 300)}`);
    error.status = response.status;
    error.retryAfterMs = retryAfterMs(response.headers.get('retry-after'));
    error.requestId = data?.error?.request_id ?? null;
    throw error;
  }

  return data;
}

async function archiveVideo(url, jobKey) {
  const response = await fetch(url, {
    signal: AbortSignal.timeout(DOWNLOAD_TIMEOUT_MS),
  });
  if (!response.ok) {
    throw new Error(`Video download failed with HTTP ${response.status}.`);
  }

  await mkdir(OUTPUT_DIR, { recursive: true });
  const safeName = jobKey.replace(/[^a-z0-9-]/gi, '_');
  const outputPath = join(OUTPUT_DIR, `${safeName}.mp4`);
  const bytes = Buffer.from(await response.arrayBuffer());
  await writeFile(outputPath, bytes);
  return outputPath;
}

async function main() {
  const utcDate = new Date().toISOString().slice(0, 10);
  const jobKey = `daily-short:${utcDate}`;
  const jobs = await loadJobs();

  if (!jobs[jobKey]) {
    // Persist intent before POST. A crash after this point must not cause an
    // automatic second submission on the next scheduler run.
    jobs[jobKey] = {
      state: 'submitting',
      createdAt: new Date().toISOString(),
      idempotencyKey: jobKey,
    };
    await saveJobs(jobs);

    try {
      const task = await requestJson(`${API_BASE}/videos/generations`, {
        method: 'POST',
        headers: {
          Authorization: `Bearer ${apiKey}`,
          'Content-Type': 'application/json',
          // Trace-only on reAPI. This header does not deduplicate the POST.
          'Idempotency-Key': jobKey,
        },
        signal: AbortSignal.timeout(POST_TIMEOUT_MS),
        body: JSON.stringify({
          model: 'seedance-2.0-mini',
          prompt:
            'A handmade ceramic cup beside an open notebook, soft morning ' +
            'window light, one slow push-in shot, natural motion, no text',
          resolution: '480p',
          aspect_ratio: '9:16',
          duration: 5,
          generate_audio: false,
          watermark: false,
        }),
      });

      if (!task.id) throw new Error('Submission returned no task ID.');

      jobs[jobKey] = {
        ...jobs[jobKey],
        state: 'processing',
        taskId: task.id,
        submittedAt: new Date().toISOString(),
      };
      await saveJobs(jobs);
    } catch (error) {
      const receivedHttpResponse = Number.isInteger(error.status);
      jobs[jobKey] = {
        ...jobs[jobKey],
        state: receivedHttpResponse ? 'submit_rejected' : 'submit_uncertain',
        error: error instanceof Error ? error.message : String(error),
        requestId: error.requestId ?? null,
      };
      await saveJobs(jobs);
      throw new Error(
        receivedHttpResponse
          ? `Submission for ${jobKey} was rejected. Review the HTTP error ` +
              'before creating a separately counted retry.'
          : `Submission for ${jobKey} is uncertain. Use ${jobKey} and the ` +
              'saved request ID, if present, to inspect logs or the dashboard. ' +
              'Do not submit again until a person reconciles the result.',
      );
    }
  }

  let job = jobs[jobKey];
  if (job.state === 'pending_review' || job.state === 'approved') {
    console.log(`${jobKey} already has an archived output: ${job.archivePath}`);
    return;
  }
  if (job.state === 'completed_no_output') {
    throw new Error(
      `${jobKey} completed without a video URL. Inspect ${job.taskId}; do not POST again.`,
    );
  }
  if (job.state === 'failed') {
    throw new Error(
      `${jobKey} failed. Review its settled usage before creating a new retry key.`,
    );
  }
  if (!job.taskId) {
    throw new Error(
      `${jobKey} has no task ID. Resolve ${job.state} manually; do not resubmit.`,
    );
  }

  if (!job.outputUrl) {
    const deadline = Date.now() + POLL_LIMIT_MS;
    let task;

    while (Date.now() < deadline) {
      try {
        task = await requestJson(`${API_BASE}/tasks/${job.taskId}`, {
          headers: { Authorization: `Bearer ${apiKey}` },
          signal: AbortSignal.timeout(GET_TIMEOUT_MS),
        });
      } catch (error) {
        const remainingMs = Math.max(deadline - Date.now(), 0);
        if (error.status === 429) {
          const waitMs = Math.min(error.retryAfterMs ?? POLL_MS, remainingMs);
          console.warn(`Rate limited; waiting ${waitMs} ms before another GET.`);
          if (waitMs > 0) await sleep(waitMs);
          continue;
        }
        const networkError = !Number.isInteger(error.status);
        const serverError = error.status >= 500 && error.status < 600;
        if (!networkError && !serverError) {
          throw error;
        }
        const waitMs = Math.min(POLL_MS, remainingMs);
        console.warn('Network or server error; retrying the same task GET.');
        if (waitMs > 0) await sleep(waitMs);
        continue;
      }

      if (task.status === 'completed' || task.status === 'failed') break;
      if (task.status !== 'processing') {
        throw new Error(`Unexpected task status: ${task.status}`);
      }
      await sleep(Math.min(POLL_MS, Math.max(deadline - Date.now(), 0)));
    }

    if (!task || (task.status !== 'completed' && task.status !== 'failed')) {
      jobs[jobKey] = { ...job, state: 'poll_timeout' };
      await saveJobs(jobs);
      throw new Error(
        'Polling timed out. The task may still be running; do not POST again.',
      );
    }

    if (task.status === 'failed') {
      jobs[jobKey] = {
        ...job,
        state: 'failed',
        usageCredits: task.usage?.credits ?? null,
        taskError: task.error ?? null,
      };
      await saveJobs(jobs);
      throw new Error(
        'Generation failed. Review settled usage before scheduling a retry.',
      );
    }

    const outputUrl = task.output?.video_urls?.[0];
    if (!outputUrl) {
      jobs[jobKey] = {
        ...job,
        state: 'completed_no_output',
        usageCredits: task.usage?.credits ?? null,
        completedAt: new Date().toISOString(),
      };
      await saveJobs(jobs);
      throw new Error('Completed task returned no video URL; do not POST again.');
    }

    // Save completion before downloading so storage trouble cannot trigger POST.
    jobs[jobKey] = {
      ...job,
      state: 'completed',
      outputUrl,
      usageCredits: task.usage?.credits ?? null,
      completedAt: new Date().toISOString(),
    };
    await saveJobs(jobs);
    job = jobs[jobKey];
  }

  try {
    const archivePath = await archiveVideo(job.outputUrl, jobKey);
    jobs[jobKey] = {
      ...job,
      state: 'pending_review',
      archivePath,
      archiveError: null,
    };
    await saveJobs(jobs);
    console.log(`Saved ${archivePath}. Review it before publishing.`);
  } catch (error) {
    jobs[jobKey] = {
      ...job,
      state: 'archive_failed',
      archiveError: error instanceof Error ? error.message : String(error),
    };
    await saveJobs(jobs);
    throw new Error(
      'Archiving failed. The task remains completed; rerun to retry only the download.',
    );
  }
}

await main();

node daily-video.mjs