一貫したキャラクター3D画像API $0.143で実現

CHARACTER: an original adult anthropomorphic warm orange fox explorer
FACE: cream muzzle, small notch in the left ear
CLOTHING: teal scarf with exactly two white stripes
ACCESSORIES: round brass goggles on forehead, navy cross-body satchel
ANCHORS: yellow triangle patch on satchel, two dark tail rings, cream tail tip
DO NOT CHANGE: warm orange fur, cream muzzle, ear-notch side, scarf pattern,
goggles, satchel patch, tail markings, compact athletic body proportions

curl https://reapi.ai/api/v1/images/generations \
  -H "Authorization: Bearer $REAPI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "wan2.7-image",
    "prompt": "Original stylized 3D cartoon character reference sheet for an adult anthropomorphic fox explorer. The same character shown in a clean front view and two three-quarter views. Identity anchors: a small notch in the left ear, teal scarf with exactly two white stripes, round brass goggles resting on the forehead, navy cross-body satchel with one yellow triangle patch, two dark rings on the tail and a cream tail tip. Warm orange fur, cream muzzle, compact athletic proportions, friendly alert expression. Neutral warm-gray studio background, soft even product lighting, full body visible, no text, no labels, no logo, no second character, no collage borders.",
    "size": "16:9",
    "resolution": "1K",
    "n": 1,
    "watermark": false
  }'

export MASTER_IMAGE_URL="https://your-temporary-or-hosted-url.example/master.png"

curl https://reapi.ai/api/v1/images/generations \
  -H "Authorization: Bearer $REAPI_API_KEY" \
  -H "Content-Type: application/json" \
  -d @- <<JSON
{
  "model": "wan2.7-image",
  "prompt": "Use the reference image only to preserve the identity of the original adult fox explorer. Create a connected five-image story sequence, one separate scene per output, in the same polished stylized 3D cartoon rendering language. Preserve all identity anchors exactly: left-ear notch, teal scarf with exactly two white stripes, round brass forehead goggles, navy cross-body satchel with one yellow triangle patch, two dark tail rings, cream tail tip, muzzle shape and body proportions. Scene 1: dawn railway platform, medium-wide view, holding one red paper ticket. Scene 2: sunlit workshop, medium view, repairing a small wooden toy airplane. Scene 3: rainy night market, full-body view, carrying one yellow umbrella. Scene 4: snowy wooden footbridge at dusk, three-quarter view, holding a small warm lantern. Scene 5: rooftop at blue hour, rear three-quarter view with face still visible, looking across the city. One fox only in every image. No text, no logo, no wardrobe change, no extra limbs, no duplicate character, and do not combine scenes into a collage.",
  "image_urls": ["$MASTER_IMAGE_URL"],
  "size": "16:9",
  "resolution": "1K",
  "n": 5,
  "enable_sequential": true,
  "watermark": false
}
JSON

import { appendFile } from 'node:fs/promises';

const baseUrl = 'https://reapi.ai';
const apiKey = process.env.REAPI_API_KEY;
const approvedMasterUrl = process.env.APPROVED_MASTER_URL?.trim();
const taskLogUrl = new URL(
  './character-series-task-ids.jsonl',
  import.meta.url,
);

const masterPrompt = process.env.MASTER_PROMPT ??
  'Original stylized 3D cartoon character reference sheet for an adult anthropomorphic fox explorer. The same character shown in a clean front view and two three-quarter views. Identity anchors: a small notch in the left ear, teal scarf with exactly two white stripes, round brass goggles resting on the forehead, navy cross-body satchel with one yellow triangle patch, two dark rings on the tail and a cream tail tip. Warm orange fur, cream muzzle, compact athletic proportions, friendly alert expression. Neutral warm-gray studio background, soft even product lighting, full body visible, no text, no labels, no logo, no second character, no collage borders.';

const groupPrompt = process.env.GROUP_PROMPT ??
  "Use the reference image only to preserve the identity of the original adult fox explorer. Create a connected five-image story sequence, one separate scene per output, in the same polished stylized 3D cartoon rendering language. Preserve all identity anchors exactly: left-ear notch, teal scarf with exactly two white stripes, round brass forehead goggles, navy cross-body satchel with one yellow triangle patch, two dark tail rings, cream tail tip, muzzle shape and body proportions. Scene 1: dawn railway platform, medium-wide view, holding one red paper ticket. Scene 2: sunlit workshop, medium view, repairing a small wooden toy airplane. Scene 3: rainy night market, full-body view, carrying one yellow umbrella. Scene 4: snowy wooden footbridge at dusk, three-quarter view, holding a small warm lantern. Scene 5: rooftop at blue hour, rear three-quarter view with face still visible, looking across the city. One fox only in every image. No text, no logo, no wardrobe change, no extra limbs, no duplicate character, and do not combine scenes into a collage.";

if (!apiKey) {
  throw new Error('Set REAPI_API_KEY before running this script.');
}

for (const [name, value] of [
  ['MASTER_PROMPT', masterPrompt],
  ['GROUP_PROMPT', groupPrompt],
]) {
  if (!value.trim()) throw new Error(`${name} cannot be empty.`);
}

const headers = {
  Authorization: `Bearer ${apiKey}`,
  'Content-Type': 'application/json',
};

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

async function readJson(response) {
  const text = await response.text();
  if (!text) return {};
  try {
    return JSON.parse(text);
  } catch {
    return { raw: text };
  }
}

async function submitGeneration(body) {
  let response;

  try {
    response = await fetch(`${baseUrl}/api/v1/images/generations`, {
      method: 'POST',
      headers,
      body: JSON.stringify(body),
    });
  } catch (error) {
    const detail = error instanceof Error ? error.message : String(error);
    throw new Error(
      `POST outcome is uncertain; do not submit it again automatically. ${detail}`,
    );
  }

  const result = await readJson(response);
  if (!response.ok) {
    throw new Error(`${response.status}: ${JSON.stringify(result)}`);
  }
  if (!result.id) {
    throw new Error(
      'POST returned no task ID; do not resubmit automatically until checked.',
    );
  }
  return result;
}

function retryDelayMs(response, attempt) {
  const retryAfter = response?.headers.get('retry-after');
  if (retryAfter) {
    const seconds = Number(retryAfter);
    if (Number.isFinite(seconds)) return Math.max(0, seconds * 1000);

    const retryAt = Date.parse(retryAfter);
    if (Number.isFinite(retryAt)) return Math.max(0, retryAt - Date.now());
  }
  return Math.min(1000 * (2 ** Math.min(attempt, 5)), 30000);
}

async function getTaskWithRetry(id, attempt) {
  let response;

  try {
    response = await fetch(`${baseUrl}/api/v1/tasks/${id}`, { headers });
  } catch (error) {
    const delay = retryDelayMs(null, attempt);
    console.warn(`Task GET failed; retrying in ${delay}ms.`);
    await sleep(delay);
    return null;
  }

  if (response.status === 429 || response.status >= 500) {
    const delay = retryDelayMs(response, attempt);
    await response.text();
    console.warn(`Task GET returned ${response.status}; retrying in ${delay}ms.`);
    await sleep(delay);
    return null;
  }

  const task = await readJson(response);
  if (!response.ok) {
    throw new Error(`${response.status}: ${JSON.stringify(task)}`);
  }
  return task;
}

async function waitForTask(id, timeoutMs = 10 * 60 * 1000) {
  const deadline = Date.now() + timeoutMs;
  let transientAttempt = 0;

  while (Date.now() < deadline) {
    const task = await getTaskWithRetry(id, transientAttempt);
    if (!task) {
      transientAttempt += 1;
      continue;
    }
    transientAttempt = 0;

    if (task.status === 'completed') return task;
    if (task.status === 'failed') {
      console.error(JSON.stringify({
        taskId: id,
        status: task.status,
        usageCredits: task.usage?.credits ?? null,
        error: task.error ?? null,
      }, null, 2));
      throw new Error(`Task ${id} failed; see the record above.`);
    }

    await sleep(5000);
  }

  throw new Error(
    `Polling timed out for ${id}. The task was not cancelled; resume GET polling instead of submitting another POST.`,
  );
}

async function recordSubmission(stage, taskId) {
  const record = {
    stage,
    taskId,
    submittedAt: new Date().toISOString(),
  };
  console.log(`Submitted ${stage}: ${taskId}`);

  try {
    await appendFile(taskLogUrl, `${JSON.stringify(record)}\n`, 'utf8');
  } catch (error) {
    console.warn(`Could not write ${taskLogUrl.pathname}; keep task ID ${taskId}.`);
  }
}

function requirePublicHttpsUrl(value) {
  let parsed;
  try {
    parsed = new URL(value);
  } catch {
    throw new Error('APPROVED_MASTER_URL must be a valid public HTTPS URL.');
  }
  if (parsed.protocol !== 'https:') {
    throw new Error('APPROVED_MASTER_URL must use HTTPS.');
  }
}

async function main() {
  if (!approvedMasterUrl) {
    const submission = await submitGeneration({
      model: 'wan2.7-image',
      prompt: masterPrompt,
      size: '16:9',
      resolution: '1K',
      n: 1,
      watermark: false,
    });
    await recordSubmission('character_master', submission.id);

    const task = await waitForTask(submission.id);
    const masterUrl = task.output?.image_urls?.[0];
    if (!masterUrl) throw new Error('Master task returned no image URL.');

    console.log(JSON.stringify({
      nextStep: 'Review this master. Rerun only after setting APPROVED_MASTER_URL.',
      masterTaskId: task.id,
      usageCredits: task.usage?.credits ?? null,
      masterUrl,
    }, null, 2));
    return;
  }

  requirePublicHttpsUrl(approvedMasterUrl);
  const submission = await submitGeneration({
    model: 'wan2.7-image',
    prompt: groupPrompt,
    image_urls: [approvedMasterUrl],
    size: '16:9',
    resolution: '1K',
    n: 5,
    enable_sequential: true,
    watermark: false,
  });
  await recordSubmission('five_scene_group', submission.id);

  const task = await waitForTask(submission.id);
  const sceneUrls = task.output?.image_urls ?? [];

  console.log(JSON.stringify({
    groupTaskId: task.id,
    usageCredits: task.usage?.credits ?? null,
    returnedSceneCount: sceneUrls.length,
    sceneUrls,
  }, null, 2));
}

main().catch((error) => {
  console.error(error instanceof Error ? error.message : error);
  process.exitCode = 1;
});

group candidate cost = $0.119 / 5 = $0.0238
project cost          = $0.024 + $0.119 = $0.143
accepted-image cost   = $0.143 / accepted scene count