ゲーム向けAI画像生成：キャッシング戦略で効率化

日次生成コスト =
  クラフトイベント数
  × キャッシュミス率
  × 受理済み資産1件あたりの完了試行回数
  × 完了生成1件あたりの単価

$0.005 × キャッシュミス率 × 受理済み資産1件あたりの完了試行回数 <= $0.002
キャッシュミス率 × 受理済み資産1件あたりの完了試行回数 <= 0.4

レシピ識別子: v3 | fire | iron

資産識別子: ember-shield | inventory-icon-v1 | z-image | 1:1 | filtered

npm install postgres

CREATE TABLE game_recipes (
  recipe_key text PRIMARY KEY,
  result_item_id text NOT NULL,
  result_display_name text NOT NULL
);

CREATE TABLE game_asset_jobs (
  asset_key text PRIMARY KEY,
  origin_recipe_key text NOT NULL REFERENCES game_recipes(recipe_key),
  result_item_id text NOT NULL,
  state text NOT NULL CHECK (state IN (
    'submitting', 'submit_uncertain', 'processing', 'completed',
    'pending_review', 'ready', 'failed', 'rejected'
  )),
  submit_owner uuid NOT NULL,
  prompt text NOT NULL,
  task_id text UNIQUE,
  source_url text,
  durable_url text,
  usage_credits integer,
  error_message text,
  created_at timestamptz NOT NULL DEFAULT now(),
  updated_at timestamptz NOT NULL DEFAULT now()
);

CREATE TABLE game_generation_budgets (
  budget_day date PRIMARY KEY,
  submissions integer NOT NULL CHECK (submissions >= 0),
  submission_limit integer NOT NULL CHECK (submission_limit > 0)
);

import { createHash, randomUUID } from 'node:crypto';
import postgres from 'postgres';

const API_BASE = 'https://reapi.ai/api/v1';
const apiKey = process.env.REAPI_API_KEY;
const databaseUrl = process.env.DATABASE_URL;
const dailyLimit = Number(process.env.DAILY_NEW_ASSET_LIMIT ?? '100');

if (!apiKey) throw new Error('Set REAPI_API_KEY on the server');
if (!databaseUrl) throw new Error('Set DATABASE_URL on the server');
if (!Number.isInteger(dailyLimit) || dailyLimit < 1) {
  throw new Error('DAILY_NEW_ASSET_LIMIT must be a positive integer');
}

const sql = postgres(databaseUrl);
const localFlights = new Map(); // L1 only; PostgreSQL owns correctness.

function hashIdentity(value) {
  return createHash('sha256')
    .update(JSON.stringify(value), 'utf8')
    .digest('hex');
}

function canonicalId(value) {
  if (typeof value !== 'string' || value.length === 0 || value.length > 200) {
    throw new Error('Item IDs must be non-empty canonical server IDs');
  }
  return value; // Preserve the exact string; do not trim, slugify, or case-fold.
}

export function recipeKey(leftItemId, rightItemId) {
  const pair = [canonicalId(leftItemId), canonicalId(rightItemId)].sort(
    (a, b) => (a < b ? -1 : a > b ? 1 : 0),
  );
  return `recipe:v3:${hashIdentity({ rulesVersion: 'v3', itemIds: pair })}`;
}

function assetKey(resultItemId) {
  return `asset:${hashIdentity({
    resultItemId,
    styleVersion: 'inventory-icon-v1',
    model: 'z-image',
    aspectRatio: '1:1',
    contentFilter: true,
  })}`;
}

async function resolveRecipe(leftItemId, rightItemId) {
  const key = recipeKey(leftItemId, rightItemId);
  const [recipe] = await sql`
    SELECT result_item_id, result_display_name
    FROM game_recipes
    WHERE recipe_key = ${key}
  `;
  if (!recipe) throw new Error('Unknown recipe');
  if (recipe.result_display_name.length > 200) {
    throw new Error('Canonical display name is too long');
  }
  return { ...recipe, recipeKey: key };
}

function publicJob(job) {
  return {
    assetKey: job.asset_key,
    state: job.state,
    taskId: job.task_id ?? null,
    url: job.state === 'ready' ? job.durable_url : null,
    usageCredits: job.usage_credits ?? null,
  };
}

async function claimSharedJob(recipe, key, prompt) {
  const owner = randomUUID();

  return sql.begin(async (tx) => {
    const created = await tx`
      INSERT INTO game_asset_jobs (
        asset_key, origin_recipe_key, result_item_id,
        state, submit_owner, prompt
      ) VALUES (
        ${key}, ${recipe.recipeKey}, ${recipe.result_item_id},
        'submitting', ${owner}, ${prompt}
      )
      ON CONFLICT (asset_key) DO NOTHING
      RETURNING *
    `;

    if (created.length === 0) {
      const [existing] = await tx`
        SELECT * FROM game_asset_jobs WHERE asset_key = ${key}
      `;
      if (!existing) throw new Error('Concurrent job was not readable');
      return { ownsSubmit: false, job: existing };
    }

    const budget = await tx`
      INSERT INTO game_generation_budgets (
        budget_day, submissions, submission_limit
      ) VALUES (
        (now() AT TIME ZONE 'UTC')::date, 1, ${dailyLimit}
      )
      ON CONFLICT (budget_day) DO UPDATE SET
        submissions = game_generation_budgets.submissions + 1,
        submission_limit = EXCLUDED.submission_limit
      WHERE game_generation_budgets.submissions < EXCLUDED.submission_limit
      RETURNING submissions
    `;
    if (budget.length === 0) throw new Error('Shared daily budget reached');

    return { ownsSubmit: true, owner, job: created[0] };
  });
}

async function markSubmitUncertain(key, owner, message) {
  const [job] = await sql`
    UPDATE game_asset_jobs
    SET state = 'submit_uncertain', error_message = ${message},
        updated_at = now()
    WHERE asset_key = ${key} AND submit_owner = ${owner}
      AND state = 'submitting'
    RETURNING *
  `;
  return job;
}

async function submitClaimedJob(claim, key, prompt) {
  let response;
  let body = '';

  try {
    response = await fetch(`${API_BASE}/images/generations`, {
      method: 'POST',
      headers: {
        Authorization: `Bearer ${apiKey}`,
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        model: 'z-image',
        prompt,
        aspect_ratio: '1:1',
        content_filter: true,
      }),
    });
    body = await response.text();
  } catch (error) {
    const job = await markSubmitUncertain(
      key,
      claim.owner,
      error instanceof Error ? error.message : String(error),
    );
    return publicJob(job ?? claim.job);
  }

  let task;
  try {
    task = JSON.parse(body);
  } catch {
    task = null;
  }

  if (!response.ok || !task?.id) {
    const message = `Unconfirmed submit response: HTTP ${response.status}`;
    const job = await markSubmitUncertain(key, claim.owner, message);
    return publicJob(job ?? claim.job);
  }

  const [saved] = await sql`
    UPDATE game_asset_jobs
    SET state = 'processing', task_id = ${task.id}, updated_at = now()
    WHERE asset_key = ${key} AND submit_owner = ${claim.owner}
      AND state = 'submitting'
    RETURNING *
  `;
  if (!saved) {
    throw new Error(`Task ${task.id} was accepted but its ID was not persisted; do not resubmit`);
  }
  return publicJob(saved);
}

async function startOrRead(recipe, key) {
  const prompt = [
    `A clean 3D inventory icon of ${recipe.result_display_name}.`,
    'One centered object, readable silhouette, plain warm background,',
    'soft studio light, no text, no logo, no existing game character.',
  ].join(' ');

  const claim = await claimSharedJob(recipe, key, prompt);
  if (!claim.ownsSubmit) return publicJob(claim.job);
  return submitClaimedJob(claim, key, prompt);
}

export async function getOrCreateCraftAsset({ leftItemId, rightItemId }) {
  const recipe = await resolveRecipe(leftItemId, rightItemId);
  const key = assetKey(recipe.result_item_id);
  const existing = localFlights.get(key);
  if (existing) return existing;

  const work = startOrRead(recipe, key).finally(() => {
    if (localFlights.get(key) === work) localFlights.delete(key);
  });
  localFlights.set(key, work);
  return work;
}

export async function pollAsset(key) {
  const [job] = await sql`
    SELECT * FROM game_asset_jobs WHERE asset_key = ${key}
  `;
  if (!job) throw new Error('Unknown asset job');
  if (job.state !== 'processing' || !job.task_id) return publicJob(job);

  const response = await fetch(`${API_BASE}/tasks/${job.task_id}`, {
    headers: { Authorization: `Bearer ${apiKey}` },
  });
  if (response.status === 429) {
    const parsed = Number.parseInt(response.headers.get('retry-after') ?? '', 10);
    return {
      ...publicJob(job),
      retryAfterSeconds: Number.isFinite(parsed) ? Math.max(parsed, 1) : 5,
    };
  }
  if (!response.ok) {
    throw new Error(`GET task failed with HTTP ${response.status}; retry this GET, not the POST`);
  }

  const task = await response.json();
  if (task.status === 'processing') return publicJob(job);
  const credits = Number.isInteger(task.usage?.credits)
    ? task.usage.credits
    : null;

  if (task.status === 'failed') {
    const [failed] = await sql`
      UPDATE game_asset_jobs
      SET state = 'failed', usage_credits = ${credits},
          error_message = ${task.error?.message ?? 'Generation failed'},
          updated_at = now()
      WHERE asset_key = ${key} AND task_id = ${job.task_id}
      RETURNING *
    `;
    return publicJob(failed);
  }

  if (task.status !== 'completed') {
    throw new Error(`Unexpected task status: ${task.status}`);
  }

  const sourceUrl = task.output?.image_urls?.[0] ?? null;
  const [completed] = await sql`
    UPDATE game_asset_jobs
    SET state = 'completed', source_url = ${sourceUrl},
        usage_credits = ${credits},
        error_message = ${sourceUrl ? null : 'Completed task returned no image URL'},
        updated_at = now()
    WHERE asset_key = ${key} AND task_id = ${job.task_id}
    RETURNING *
  `;
  return publicJob(completed);
}

export async function stageForReview(key, durableUrl) {
  const [job] = await sql`
    UPDATE game_asset_jobs
    SET state = 'pending_review', durable_url = ${durableUrl},
        updated_at = now()
    WHERE asset_key = ${key} AND state = 'completed'
      AND source_url IS NOT NULL
    RETURNING *
  `;
  if (!job) throw new Error('Only an archived completed asset can enter review');
  return publicJob(job);
}

export async function reviewAsset(key, accepted, reason = null) {
  const nextState = accepted ? 'ready' : 'rejected';
  const [job] = await sql`
    UPDATE game_asset_jobs
    SET state = ${nextState}, error_message = ${reason}, updated_at = now()
    WHERE asset_key = ${key} AND state = 'pending_review'
    RETURNING *
  `;
  if (!job) throw new Error('Asset is not pending review');
  return publicJob(job);
}

受理済み資産1件あたりのコスト =
  確定生成クレジット合計×$0.001/受理済み資産