用 n8n + OpenAI Vision 分析竞品 YouTube 缩略图并交付审批后的 ThumbCanvas 方案

收集视频简报与竞品 URL → 提取公开元数据与视觉证据 → AI 生成三个原创方向 → 人工审核门 → ThumbCanvas 链接 + Google Sheets 审计

给谁

YouTube 创作者、缩略图设计师和内容团队，希望基于可见证据获得原创方向，而非直接复制竞品或依赖虚假的 CTR 预测

你会得到

输入竞品 YouTube URL 和计划视频简报，经 OpenAI Vision 分析缩略图视觉证据后生成三个原创方向，人工审核批准后生成 ThumbCanvas 深度链接并追加 Google Sheets 审计行

你需要

n8n, Google Sheets

步骤

1. 收集并验证简报

   在 n8n Form Trigger 页面填写计划视频标题、承诺、受众、目标关键词、品牌色板、可选缩略图文字（最多4词）和 2–3 个竞品 YouTube URL。提交后由 Normalize and Validate Brief 代码节点规范化字段、提取 11 位视频 ID、去重并验证；不符合条件时返回 HTTP 400 错误页面，提示修正。

   搭建指导 · 来源原文。「Overview Setup and Safety」粘性说明节点的 content 字段（总览与安全，逐字保留）

   复制提示词

   ## Analyze competitor YouTube thumbnails with OpenAI and save approved briefs to Google Sheets
   
   ### Who this is for
   YouTube creators, thumbnail designers, and content teams who want evidence-informed creative directions without copying competitors or pretending that visual analysis guarantees click-through rate.
   
   ### What it does
   This workflow collects a planned-video brief plus two or three public competitor YouTube URLs. It validates and deduplicates the links, retrieves public oEmbed metadata, and sends each public thumbnail to OpenAI for a schema-validated visual analysis. It then aggregates the usable evidence and produces exactly three original thumbnail concepts.
   
   A human review page shows the public sources, the analysis, and all three concepts. Only an approved concept becomes a pre-filled [ThumbCanvas](https://thumbcanvas.com/create-thumbs) link. The approved decision is then appended to Google Sheets as an audit row. Rejected concepts create neither a ThumbCanvas link nor a sheet row.
   
   ### Setup
   1. Add an OpenAI credential to both OpenAI nodes. The default model is `gpt-4.1-mini`; change it in **Set Template Configuration** if your account uses another vision-capable model.
   2. Connect Google Sheets OAuth in **Append Approved Brief to Google Sheets**. Select a spreadsheet and a sheet. Use these header names: `approved_at`, `planned_video_title`, `target_keyword`, `audience`, `competitor_urls`, `approved_concept`, `concept_evidence`, `thumbcanvas_url`, `openai_model`, `analysis_status`, `review_notes`, `workflow_version`.
   3. Publish the workflow, open the production form URL, and submit a brief.
   
   ### Important boundaries
   OpenAI vision can misread small text or visual details, so the workflow exposes sources and limitations for human checking. It never predicts CTR. Enter only public competitor links and non-confidential brief data. OpenAI receives the thumbnail URL and brief context; Google Sheets stores only the approved row. n8n may retain execution data according to your instance settings.
   
   ThumbCanvas generation happens only when the reviewer opens the final link. No image is auto-published.

2. 获取公开证据与视觉分析

   每个竞品生成一个 n8n 项目。HTTP Request 节点调用 YouTube 公开 oEmbed 端点获取标题和作者（无需 YouTube API 密钥）。OpenAI Vision 节点以 high image detail 分析公开缩略图 URL，返回包含主体、文字、构图、对比、情绪、钩子、可迁移模式、复制风险、置信度和局限性的严格 JSON Schema。Validate Structured Visual Analysis 节点检查 schema 完整性；失败项目保留并标记，汇总状态为 complete / partial / failed，不静默丢弃。

   运行提示词 · 来源原文。Analyze Each Thumbnail with OpenAI Vision 节点的 System Message 字段

   复制提示词

   You are a conservative visual analyst. Describe only visible thumbnail evidence. Do not infer views, click-through rate, audience response, or creator intent. Return the required JSON schema.

   运行提示词 · 来源原文。Analyze Each Thumbnail with OpenAI Vision 节点的 User Message 字段（表达式）

   复制提示词

   ={{ 'Analyze this public YouTube thumbnail. Video ID: ' + $json.video_id + '. Public title: ' + $json.source_title + '. Channel: ' + $json.author_name + '. Identify the focal subject, visible text, composition, contrast, emotion, visual hook, transferable design patterns, copy risks, confidence from 0 to 1, and limitations. Small or uncertain text must be marked uncertain.' }}

3. 生成概念并人工审核

   第二个 OpenAI 调用接收简报与已验证视觉证据，严格结构化输出恰好三个原创方向（好奇心缺口、高风险、前后对比），每个含来源视频 ID、依据、构图、色板、生产提示词和风险。工作流在 n8n 表单审核页面暂停最多七天，审核员可查看公开来源、对比证据、批准一个概念、添加备注或全部拒绝。未获批准不生成 ThumbCanvas 链接，也不写入 Google Sheets。

   运行提示词 · 来源原文。Generate Three Evidence-Linked Concepts 节点的 System Message 字段

   复制提示词

   You are a YouTube thumbnail art director. Produce original concepts grounded in supplied evidence, avoid copying protected expression, and never claim guaranteed performance. Return the required JSON schema.

   运行提示词 · 来源原文。Generate Three Evidence-Linked Concepts 节点的 User Message 字段（表达式，运行时引用上游构建的 concept_prompt）

   复制提示词

   ={{ $json.concept_prompt }}

4. 交付 ThumbCanvas 并审计

   人工批准后，Resolve Human Approval 代码节点将选定方案的生产提示词和 16:9 宽高比编码为 ThumbCanvas 创建 URL。打开该 URL 是独立操作，可能消耗审核者的 ThumbCanvas 额度。Map Approved Brief to Audit Columns 节点将结果映射为 12 列固定形状，由 Google Sheets 节点自动追加到匹配表头的表格。最终 Verify Audit Write Result 检查区分成功写入与凭证/目标失败；若 Sheets 写入失败，ThumbCanvas 链接仍保留，但明确标记审计失败，需修复后重跑。

n8n 工作流：收集简报 → 视觉分析 → 生成概念 → 人工审核 → ThumbCanvas 交付与审计