http_server_lua_demo

A small Lua-hosted web page with a “Hello World” message and a browser switch that reports changes back to Lua.

In plain words
What is it for?
Use it to demonstrate a simple Lua HTTP server, static web files, and a browser control that calls into Lua.
Why use it?
It provides a ready-made example for testing how a Lua program can serve a web page and receive browser actions.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/espressif/esp-claw/http_server_lua_demo
Any agent
npx skills add espressif/esp-claw --skill http_server_lua_demo
Clone the repo
git clone --depth 1 https://github.com/espressif/esp-claw

Made for: Claude Code, Codex.

Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 688 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00027 $0.00688
Opus 5 $0.00014 $0.00344
Sonnet 5 $0.00005 $0.00138
Haiku 4.5 $0.00003 $0.00069

Measured 2d ago against content hash ca45e4c2b8d2, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

http_server_lua_demo scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (assets/app.js), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

components/lua_modules/lua_module_http_server/skills/http_server_lua_demo/SKILL.md · 115 lines

How it starts

The opening of the file, as written. The whole thing — 115 lines — stays where its author put it; the contents beside it link to each section on GitHub.

HTTP Server Lua Demo

Use this skill when the user wants a simple Lua HTTP server demo page, a Hello World web UI, or a browser switch that calls back into Lua.

Run exactly one bundled Lua script asynchronously with the Lua script execution capability.

If script execution returns an error, report that error directly to the user.

Script Args Schema

{
  "type": "object",
  "properties": {
    "app_id": {
      "type": "string",
      "description": "Optional URL-safe app id. Defaults to lua_demo."
    },
    "web_root": {
      "type": "string",
      "description": "Optional absolute directory for static web files. Defaults to {CUR_SKILL_DIR}/assets."
    }
  }
}

Tool Call Inputs

Default action:

{
  "path": "{CUR_SKILL_DIR}/scripts/lua_demo_server.lua",
  "args": {
    "app_id": "lua_demo",
    "web_root": "{CUR_SKILL_DIR}/assets"
  }
}

Run the bundled Lua script asynchronously so the HTTP callbacks stay alive:

  • Script: {CUR_SKILL_DIR}/scripts/lua_demo_server.lua
  • Capability: lua_run_script_async
  • Timeout: 0
  • Name: http_server_lua_demo
  • Exclusive: http_server_lua_demo
  • Replace: true
  • Args: optional object

Example args:

{
  "app_id": "lua_demo",
  "web_root": "{CUR_SKILL_DIR}/assets"
}

After the script starts, open:

/lua/lua_demo/

Keep the trailing slash. Opening /lua/lua_demo without the trailing slash can make browsers resolve relative assets under /lua/ instead of /lua/lua_demo/. The bundled page uses absolute asset paths for the default lua_demo app id; if app_id is changed, update the HTML asset URLs or keep using the exact trailing-slash URL.

Behavior

The script mounts the bundled assets/ directory with http_server and registers:

  • GET /api/lua/lua_demo/state
  • POST /api/lua/lua_demo/toggle

The page displays "Hello World" and a switch. When the switch changes, the browser posts the new state to Lua, and Lua logs:

[http_server_lua_demo] {"enabled":true,"event":"switch_toggled"}

Read the full file on GitHub · 115 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 115 lines · 27 tokens per session scan A ca45e4c2b8d2

Subscribe to this mod's changes

http_server_lua_demo is a skill published in the GitHub repository espressif/esp-claw (2,069 stars, last pushed yesterday), licensed Apache-2.0. It adds 27 tokens to every session and 688 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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