We did not invent a latency or success-rate benchmark. Those values vary by account, queue, model configuration, and input. The sample records your real elapsed time, API usage, terminal status, and failure details so you can produce a defensible benchmark in your own environment.

Why a Character Reference Is Not Optional

The prompt tells the model what happens. The character reference tells it who the story is happening to.

For a recurring role, keep these fields stable:

• Name
• Age range and presentation
• Hair silhouette
• Signature clothing colors
• One distinctive prop
• Primary reference image
• Optional side and three-quarter references

In this example, the role is a courier with short dark hair, a yellow rain jacket, and a red messenger bag. Those details are compact enough to repeat and distinct enough to audit.

Step 1: Prepare the Server Environment

Use Node.js 20 or newer so fetch, FormData, and Blob are available. Keep the key in a server-only environment variable.

export LLAMAGEN_API_KEY="your_server_side_key"

Do not expose this key in a browser bundle, mobile application, public repository, or client-side request. If your product has a frontend, send the user's brief to your own backend and let that backend call LlamaGen.AI.

The workflow has four network operations:

Step 2: Run the TypeScript Quickstart

Save the following as comic-quickstart.ts, put a character image at ./courier-reference.png, and run it from your server environment.

import { basename } from "node:path";
import { readFile } from "node:fs/promises";
import { randomUUID } from "node:crypto";

const API_BASE = "https://api.llamagen.ai";
const API_KEY = process.env.LLAMAGEN_API_KEY;

if (!API_KEY) {
  throw new Error("Set LLAMAGEN_API_KEY before running this script.");
}

type UploadResponse = {
  code?: number;
  fileUrl: string;
};

type Usage = {
  total_comics?: number;
  redraw_panels?: number;
  amount?: number;
};

type Generation = {
  id: string;
  status: "LOADING" | "PROCESSED" | "FAILED" | "CANCELLED" | string;
  usage?: Usage;
  comics?: Array<{
    page?: number;
    panels?: Array<{
      panel?: number;
      image?: string;
      assetUrl?: string;
      caption?: string;
    }>;
  }>;
  error?: unknown;
};

async function api<T>(path: string, init: RequestInit = {}): Promise<T> {
  const response = await fetch(`${API_BASE}${path}`, {
    ...init,
    headers: {
      Authorization: `Bearer ${API_KEY}`,
      ...init.headers,
    },
  });

  const text = await response.text();
  const body = text ? JSON.parse(text) : null;

  if (!response.ok) {
    throw new Error(
      `Comic API ${response.status}: ${JSON.stringify(body)}`,
    );
  }

  return body as T;
}

async function uploadReference(filePath: string) {
  const bytes = await readFile(filePath);
  const form = new FormData();
  form.set("file", new Blob([bytes]), basename(filePath));

  return api<UploadResponse>("/v1/comics/upload", {
    method: "POST",
    body: form,
  });
}

async function waitForGeneration(
  generationId: string,
  timeoutMs = 10 * 60_000,
) {
  const startedAt = Date.now();

  while (Date.now() - startedAt < timeoutMs) {
    const job = await api<Generation>(
      `/v1/comics/generations/${generationId}`,
    );

    console.log(
      JSON.stringify({
        generationId,
        status: job.status,
        elapsedMs: Date.now() - startedAt,
        usage: job.usage,
      }),
    );

    if (job.status === "PROCESSED") return job;

    if (job.status === "FAILED" || job.status === "CANCELLED") {
      throw new Error(
        `Generation ended as ${job.status}: ${JSON.stringify(job.error)}`,
      );
    }

    await new Promise((resolve) => setTimeout(resolve, 4_000));
  }

  throw new Error(`Generation ${generationId} timed out.`);
}

async function main() {
  const startedAt = Date.now();

  try {
    const reference = await uploadReference("./courier-reference.png");

    const created = await api<Generation>("/v1/comics/generations", {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        "Idempotency-Key": randomUUID(),
      },
      body: JSON.stringify({
        prompt: [
          "Create one four-panel comic page in a restrained cinematic manga style.",
          "Panel 1: Ren enters a rain-soaked station and notices a golden key.",
          "Panel 2: Close view as Ren lifts the key and studies it.",
          "Panel 3: Ren runs toward an old locked service door.",
          "Panel 4: Ren opens the door and warm light spills into the station.",
          "Keep the same face, haircut, yellow jacket, and red messenger bag.",
          "Leave clean space for later lettering.",
        ].join("\n"),
        preset: "japanese_manga",
        size: "1024x1024",
        fixPanelNum: 4,
        language: "en",
        comicRoles: [
          {
            name: "Ren",
            age: 22,
            gender: "male",
            dress: "yellow rain jacket, black trousers, red messenger bag",
            image: reference.fileUrl,
          },
        ],
      }),
    });

    const firstPass = await waitForGeneration(created.id);
    console.log("first_pass_complete", {
      id: firstPass.id,
      elapsedMs: Date.now() - startedAt,
      usage: firstPass.usage,
      pages: firstPass.comics?.length ?? 0,
    });

    // Example review result: panel 3 lost the red bag.
    const repairQueued = await api<Generation>(
      `/v1/comics/generations/${created.id}`,
      {
        method: "PATCH",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({
          page: 0,
          panel: 2,
          panelPrompt:
            "Ren runs toward the service door. Preserve his exact face, short dark hair, yellow rain jacket, and visible red messenger bag.",
          images: [reference.fileUrl],
        }),
      },
    );

    console.log("repair_queued", {
      id: repairQueued.id,
      usage: repairQueued.usage,
    });

    const repaired = await waitForGeneration(created.id);
    console.log("workflow_complete", {
      id: repaired.id,
      totalElapsedMs: Date.now() - startedAt,
      finalStatus: repaired.status,
    });
  } catch (error) {
    console.error("comic_workflow_failed", {
      elapsedMs: Date.now() - startedAt,
      message: error instanceof Error ? error.message : String(error),
    });
    process.exitCode = 1;
  }
}

await main();

Run it with:

npx tsx comic-quickstart.ts

The sample intentionally logs structured objects. In production, send the same fields to your observability system and include your own request or project identifier.

Step 3: Review the Four Panels Like a Dataset

Do not approve a page because it looks attractive at thumbnail size. Audit each panel against the character lock:

Treat this as machine-readable quality control if you are building a larger pipeline. Store a pass/fail reason per panel, not just a page-level thumbs-up.

Step 4: Repair One Panel, Not the Whole Page

The fastest repair prompt names both the new action and the elements that may not change.

Panel 3 repair:
Ren runs toward the service door.
Preserve his exact face, short dark hair, yellow rain jacket,
and visible red messenger bag.
Keep the rainy station and left-to-right movement.

The panel indexes are zero-based, so the visible third panel is panel: 2. The update endpoint can accept panelPrompt, reference images, or a replacement caption.

This matters operationally. Rebuilding all four panels can introduce three new continuity risks while fixing one old one. Targeted repair narrows the review surface.

Production Hardening Checklist

Before shipping the integration, add these controls:

1. Use a unique idempotency key for each intended generation.
2. Store the generation ID immediately after creation.
3. Poll with a fixed interval or backoff and enforce a timeout.
4. Log status, elapsed time, usage, and failure payloads.
5. Keep uploaded reference URLs with the project record.
6. Validate that the returned panel count matches the request.
7. Review identity, costume, props, scene continuity, and lettering space separately.
8. Repair only the affected panel whenever possible.
9. Never expose the API key to client-side code.
10. Read current usage and pricing from the API response and documentation instead of hardcoding old assumptions.

For longer sequences, switch from fixPanelNum to pagination.totalPages and pagination.panelsPerPage. Do not send both modes in one create request.

When to Use the API Instead of the Editor

Use the Comic API when comics are generated inside your own product, batch job, educational tool, publishing pipeline, or customer workflow.

Use the visual editor when a creator wants to explore the story interactively, compare alternatives, or art-direct each page by hand. Many teams use both: the API creates and logs the repeatable first pass, while the editor handles exceptional revisions.

If your story structure is still changing, plan it before making finished panels. The next guide, Storyboard First or Comic Panels First?, shows how to measure the rework difference.

FAQ

Can I generate exactly four panels?

Yes. Send fixPanelNum: 4 for a single-page four-panel request. For multiple pages, use the pagination object instead.

How do I keep one character consistent?

Upload a clean reference image, pass its returned fileUrl in comicRoles[].image, keep the role name and costume description stable, and audit every returned panel before continuing the sequence.

Can I regenerate only one bad panel?

Yes. Send a PATCH request with the zero-based page and panel indexes plus a new panelPrompt, optional reference images, or caption.

Should I retry a failed create request with the same idempotency key?

Use the idempotency behavior documented by LlamaGen.AI so network retries do not accidentally create duplicate work. Use a new key only when you intentionally want a new generation.

Does this sample expose real benchmark numbers?

No. It exposes the instrumentation needed to capture your real numbers. Publish latency, usage, and failure rates only after running the same input repeatedly in your own account and recording the conditions.

Sources and Editorial Disclosure

• LlamaGen.AI Comic API documentation, checked October 10, 2026
• LlamaGen.AI Comic API
• Meta Model API consistency cookbook, consulted for the broader principle of anchoring an image series to stable visual references

Written by Jay and technically reviewed against the live endpoint contract by the LlamaGen.AI content team. Product behavior can change; the linked documentation is the source of truth.

Ready to build the workflow? Open the LlamaGen.AI Comic API, create a server-side key, and run the quickstart with your own character reference.

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