What is langbot-plugin-dev?

A development and debugging guide for LangBot plugins. Plugins are add-ons that can respond to events, handle commands, or provide tools inside LangBot.

It helps build plugin manifests and Python components, use LangBot features such as messaging and language-model calls, test plugins over WebSocket, and control a running LangBot instance through MCP.

It explains the plugin structure and the available LangBot software interface, reducing uncertainty when creating or fixing an add-on.

langbot-plugin-dev — Skill for Claude Code and Codex by langbot-app

About the project

LangBot is an open-source platform for connecting language models to instant-messaging services so developers can build chatbots that converse, use tools, and execute tasks. It supports bot management, knowledge bases, plugins, and multiple chat platforms, and the catalogue entries provide skills, MCP tools, and instructions for working with it.

langbot-app/LangBot · 18,213 stars · on GitHub · space.langbot.app

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.

Any agent

npx skills add langbot-app/LangBot --skill langbot-plugin-dev

Clone the repo

git clone --depth 1 https://github.com/langbot-app/LangBot

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/langbot-app/langbot/langbot-plugin-dev/github.svg)](https://agentmods.dev/skills/langbot-app/langbot/langbot-plugin-dev)

Your own site

<a href="https://agentmods.dev/skills/langbot-app/langbot/langbot-plugin-dev"><img src="https://agentmods.dev/badge/skills/langbot-app/langbot/langbot-plugin-dev/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/langbot-app/langbot/langbot-plugin-dev"><img src="https://agentmods.dev/badge/skills/langbot-app/langbot/langbot-plugin-dev.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 110 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 3,940 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

Snyk pass 7 Sept 2026
NVIDIA SkillSpector warn 7 Sept 2026

SkillSpector: 3 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

high Privilege Escalation · line 17
Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.

Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
medium Data Exfiltration · line 314
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
medium Data Exfiltration · line 332
Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.

How audits are shown

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.

Model	Per session	Once invoked
Fable 5.1	$0.00110	$0.03940
Opus 5.5	$0.00044	$0.01576
Sonnet 5.5	$0.00022	$0.00788
Haiku 4.5	$0.00011	$0.00394

Measured 23d ago against content hash 7d38fc01859e, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

langbot-plugin-dev scanned grade A with 1 finding 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 23d ago.

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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -X POST $BASE/api/v1/user/init \

skills/skills/langbot-plugin-dev/SKILL.md · 485 lines

How it starts

The opening of the file, as written. The whole thing — 485 lines — stays where its author put it; the contents beside it link to each section on GitHub.

LangBot Plugin Development & Debugging

Controlling a running instance via MCP

Beyond writing code, you can drive a live LangBot instance over MCP — no raw HTTP needed. Two MCP servers exist (both reuse existing API keys; see AGENTS.md):

LangBot instance — http://<host>:5300/mcp (auth: web-UI lbk_ key or the api.global_api_key from config.yaml). Manage bots, pipelines, models, knowledge bases, and skills. See the langbot-mcp-ops skill.
LangBot Space marketplace — https://space.langbot.app/mcp (auth: Personal Access Token). Search plugins / MCP servers / skills. See the langbot-space-ops skill.

Any change to an agent-accessible HTTP API endpoint must keep the matching MCP tool and these skills in sync.

Plugin Architecture

A LangBot plugin consists of:

MyPlugin/
├── manifest.yaml          # Plugin metadata, config schema
├── main.py                # BasePlugin subclass (entry point, shared state)
├── components/
│   ├── event_listener/    # Hook pipeline events
│   │   ├── collector.yaml
│   │   └── collector.py
│   ├── commands/          # !command handlers
│   │   ├── mycommand.yaml
│   │   └── mycommand.py
│   └── tools/             # LLM function-call tools
│       ├── mytool.yaml
│       └── mytool.py

Each component has a .yaml (metadata) and .py (implementation).

README & i18n convention (enforced on the marketplace)

A plugin published to LangBot Space serves a localized README on its detail page. The resolver (langbot-space PluginService.GetPluginREADME) works like this:

Root README.md MUST be in English. It is the default and the fallback — when no per-language README matches the viewer's locale, the page serves the root README.md. A non-English root README makes the English/default view show the wrong language.
All other languages live under readme/README_{lang}.md — e.g. readme/README_zh_Hans.md, readme/README_ja_JP.md. The 8 supported locales: en_US, zh_Hans, zh_Hant, ja_JP, th_TH, vi_VN, es_ES, ru_RU.
manifest.yaml metadata.label / metadata.description should carry the same 8-locale i18n set (repository must be a real, alive URL).

Read the full file on GitHub · 485 lines

Files

What ships with it

1 file 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.

references/test-env-setup.md 2.9 KB

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.

23d ago Changed 7d38fc01859e
1mo ago First seen · 485 lines · 110 tokens per session scan A 2b92d4ba9e36

Subscribe to this mod's changes

langbot-plugin-dev is a skill published in the GitHub repository langbot-app/LangBot (18,213 stars, last pushed today), licensed Apache-2.0. It adds 110 tokens to every session and 3,940 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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langbot-plugin-dev