Weixin Long Image

Turn Weixin/Wechat replies into readable image cards by rendering HTML into long PNG screenshots. Use when a Weixin direct-chat reply would exceed 150 Chines...

Security Scan

The skill's purpose (render HTML to a long PNG for Weixin) matches its code and instructions, but there are coherence gaps — notably no declared runtime dependency (Playwright/Chromium/Python) or install steps — that you should understand before using it.

Purpose & Capability

The name/description match the shipped assets and script: templates + a renderer that produces full-page PNG screenshots. However, the package metadata declares no required binaries or dependencies while the included script clearly needs Python and the Playwright library (and a Chromium browser). That mismatch is an omission/oversight rather than direct maliciousness, but it is disproportionate to claim 'no required binaries'.

Instruction Scope

SKILL.md limits the agent to composing HTML, rendering it with scripts/render_long_image.py, sending the PNG via the message tool (channel=openclaw-weixin), and deleting temp files afterward. Those actions align with the stated purpose. One runtime nuance: the renderer opens the HTML in a real browser and will load any resources referenced by that page (remote images, CSS, or file:// URLs), which the instructions do not explicitly constrain.

Install Mechanism

There is no install spec, but the script requires Playwright and a Chromium runtime. Playwright often involves fetching browser binaries at install/run time; the skill provides no guidance about installing Playwright, pinning versions, or where the browser will come from. The lack of an install declaration is a coherence/operational risk: the skill will fail or cause unreviewed downloads in some environments.

Credentials

The skill requests no environment variables or external credentials and does not touch unrelated config paths. That is proportionate for its rendering task.

Persistence & Privilege

The skill is not always-enabled and does not request persistent elevated privileges. It writes temporary HTML/PNG files per run and instructs to delete them; that behavior is consistent with its purpose.

What to consider before installing

This skill appears to do what it says (turn HTML into long PNGs), but before installing or running it you should: 1) Ensure the agent environment has Python 3 and Playwright (and Chromium) installed from trusted sources — the repository does not declare these dependencies. 2) Be cautious with untrusted HTML: the renderer opens pages in a real browser and will fetch remote resources (images/CSS/JS) or follow file:// references; malicious or private content could be exfiltrated via network requests or cause unexpected behavior. 3) Confirm your runtime will auto-download browser binaries (Playwright behavior) or install them explicitly to avoid silent network downloads. 4) If you need stricter safety, run the renderer in a sandboxed environment, audit the HTML before rendering, and ensure temporary outputs are cleaned (SKILL.md recommends deleting them). If you want, I can: list exact installation steps for Playwright + Chromium, or propose a hardened invocation that disables network access during rendering.

Use this skill to turn rich HTML layouts into long PNGs for Weixin delivery.

Core Rule

In Weixin direct chats, if the reply body for the user would exceed 150 Chinese characters, treat this as a hard rule: prefer this skill over a long plain-text message.

When To Use

Use this skill when any of these is true:

• The Weixin reply would be long and hard to read as plain chat text.
• The user asks for a card, poster, beautiful layout, or visually polished output.
• The content needs HTML rendering power, such as:
  • charts
  • tables
  • timelines
  • curves / trend visuals
  • relation diagrams
  • dashboards
  • mixed text + image layouts
• You want stable final presentation rather than chat-native formatting.

Default Visual Standard

Unless the user explicitly wants a poster/card/dashboard style, default to a WeChat public-article layout, not a centered floating card.

Night Rule

In Asia/Shanghai time, if the image is being prepared at 22:00 or later, default to a dark-mode article template to reduce eye strain, unless the user explicitly asks for a light theme.

Default article layout

• Use a plain white page background.
• Keep only moderate side margins for readability.
• Do not wrap the whole article in a large rounded card with heavy shadow.
• Prefer continuous reading flow, like a WeChat public account article.
• Use readable typography, generous line height, and responsive images.

Default dark article layout after 22:00

• Use a dark page background with softened contrast.
• Keep the same article flow and margins as the daytime template.
• Avoid excessive glow, neon accents, or dashboard-style visuals unless explicitly requested.
• Preserve readability first: muted metadata, bright headings, comfortable code blocks, and responsive images.

Use card style only when appropriate

Reserve card/poster/dashboard styling for cases like:

• cover cards
• poster-like announcements
• KPI / dashboard views
• side-by-side comparison blocks
• highly visual share cards

For ordinary long articles, analysis notes, translated writeups, and image-heavy explanations, prefer article layout.

Reusable Templates

Use assets/wechat-article-template.html as the default starting point for daytime article-style pages. Use assets/wechat-article-template-dark.html as the default starting point for article-style pages prepared at or after 22:00 Asia/Shanghai.

They provide:

• WeChat-like article spacing
• narrower side margins
• no outer card shell
• responsive images
• readable tables
• wrapped code blocks
• simple note/tip blocks
• matched light/dark article styles

Workflow

1. Write a complete HTML document first.
2. For article-like content, choose the template by time:
   • before 22:00 Asia/Shanghai → assets/wechat-article-template.html
   • at or after 22:00 Asia/Shanghai → assets/wechat-article-template-dark.html
3. Render the HTML with scripts/render_long_image.py.
4. Send the PNG with the message tool using an absolute local path.
5. After the message send succeeds, immediately delete temporary render artifacts (.png and temporary .html) unless the user explicitly asked to keep them.
6. In Weixin direct chats, use message for any progress update; do not rely on multi-part assistant text arriving in order.

Quick Start

python3 scripts/render_long_image.py \
  --input /absolute/path/to/page.html \
  --png-out /absolute/path/to/output.png

You may also pass raw HTML via --input or stdin.

Input Rules

• The script accepts complete HTML only.
• --input can be a file path or inline HTML.
• If --input is omitted, read HTML from stdin.
• --html-out is optional.
  • If provided, persist the rendered HTML there.
  • If omitted and --input is an existing HTML file, reuse that file.
  • If omitted and the source is inline HTML or stdin, create a temporary HTML file and auto-delete it after rendering.
• If the source content starts as text, convert it into HTML first.

Rendering Guidance

• Build for phone reading first.
• For long-form articles, prefer article layout over card layout.
• For tables, charts, diagrams, and mixed media, define layout explicitly in CSS instead of relying on browser defaults.
• If images are embedded in the HTML, make them responsive with max-width: 100% unless overflow is intentional.
• Use absolute output paths so the PNG can be delivered reliably.
• If the content is sensitive, write outputs inside the workspace or /tmp, send the PNG, then remove temporary files if appropriate.

Sending

Use message with the generated PNG path.

• action=send
• channel=openclaw-weixin
• media=/absolute/path/to/output.png
• message=一句很短的说明

Post-send cleanup

For temporary outputs, once message reports success, delete the local render artifacts immediately.

Typical cleanup:

rm -f /absolute/path/to/output.png /absolute/path/to/output.html

Rules:

• Prefer writing temporary outputs under /tmp.
• Delete the PNG after a successful send unless the user asked to keep the file.
• Delete the HTML too when it is only an intermediate artifact.
• If render_long_image.py used inline HTML or stdin without --html-out, the script already auto-deletes its temporary HTML file; you still need to delete the PNG after send.

After a user-visible message send, reply with NO_REPLY to avoid duplicates.

Troubleshooting

• If Playwright cannot launch Chromium, verify the local Playwright browser runtime is installed.
• If the screenshot looks clipped, increase --width or fix the HTML/CSS layout first.
• If the result is too tall, split the content into multiple HTML pages and render multiple images.
• If the content is short and visually simple, skip this skill and reply normally.

Assets

• assets/wechat-article-template.html: Default daytime HTML template for WeChat-article-style long images.
• assets/wechat-article-template-dark.html: Default night-mode HTML template for WeChat-article-style long images after 22:00 Asia/Shanghai.

Script

• scripts/render_long_image.py: Render complete HTML into a long PNG screenshot.