A guide for sending and receiving messages with NATS, a system that lets services communicate by sending messages. It applies to the Self Serve Express backend-for-frontend, a server that connects the web app to other services.

Use it when publishing messages, subscribing to them, making request-and-reply calls, resolving project IDs, or investigating NATS connection and timeout problems.

It helps avoid incorrect message destinations, bypassed connection handling, and unclear timeout or connection failures. It also explains how errors should reach callers.

How linuxfoundation/lfx-self-serve configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to linuxfoundation/lfx-self-serve. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/linuxfoundation/lfx-self-serve/main/.claude/skills/nats/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/linuxfoundation/lfx-self-serve

Made for: Claude Code.

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/linuxfoundation/lfx-self-serve/nats/github.svg)](https://agentmods.dev/skills/linuxfoundation/lfx-self-serve/nats)

Your own site

<a href="https://agentmods.dev/skills/linuxfoundation/lfx-self-serve/nats"><img src="https://agentmods.dev/badge/skills/linuxfoundation/lfx-self-serve/nats/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/linuxfoundation/lfx-self-serve/nats"><img src="https://agentmods.dev/badge/skills/linuxfoundation/lfx-self-serve/nats.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 72 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 627 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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	$0.00072	$0.00627
Opus 5.5	$0.00029	$0.00251
Sonnet 5.5	$0.00014	$0.00125
Haiku 4.5	$0.00007	$0.00063

Measured 2mo ago against content hash 28df3c5a2767, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

nats 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 2mo 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.

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.

.claude/skills/nats/SKILL.md · 36 lines

How it starts

The opening of the file, as written. The whole thing — 36 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Self Serve NATS Skill

You are publishing, subscribing, or making NATS request/reply calls from the Self Serve Express BFF.

When to use

A backend endpoint needs to look up a resource via NATS request/reply (e.g., project RPC for ID resolution).
A backend service consumes a NATS subject (e.g., listening for indexer or persona updates).
A new server-side code path needs to publish to NATS.
Investigating "no responder" / timeout / connection errors in nats.service.ts.

Workflow

Re-read docs/architecture/backend/nats-integration.md (the reference linked below). It documents the singleton connection, request/reply timeout defaults, project resolution, and the subject conventions Self Serve consumes.
Do not bypass nats.service.ts — it is a protected file. Use the existing helper methods; add new methods through code-owner review.
Use the right subject vocabulary — subjects are owned by their producing service (per /lfx-skills:lfx). Do not invent new subjects from Self Serve; coordinate with the owning service repo first.
Set explicit timeouts on request/reply calls. Failures must surface as MicroserviceError (or equivalent) and route through next(error) — never res.status(500).json().
Log via the logger service (not serverLogger). Use logger.debug for subject + reply tracing, logger.error for failed requests.
Mock mode — for local dev without the full platform stack, follow docs/architecture/backend/nats-integration.md and the mock-mode setup in /setup. Do not introduce ad-hoc mocks inside production code paths.

Reference

docs/architecture/backend/nats-integration.md — the canonical NATS architecture doc. Treat this as the source of truth; do not maintain a separate copy under this skill.

Scope boundaries

This skill does NOT cover the platform NATS deployment (routes to lfx-v2-helm).
It does NOT cover indexer or FGA-sync subject contracts (routes to lfx-v2-indexer-service and lfx-v2-fga-sync via /lfx-skills:lfx).
It does NOT cover the upstream auth or persona NATS contracts (route to lfx-v2-auth-service / lfx-v2-persona-service).

Read the full file on GitHub · 36 lines

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.

2mo ago First seen · 36 lines · 72 tokens per session scan A 28df3c5a2767

Subscribe to this mod's changes

nats is a skill published in the GitHub repository linuxfoundation/lfx-self-serve (16 stars, last pushed today), licensed MIT. It adds 72 tokens to every session and 627 once invoked, about $0.0003 per session on Opus 5.5. 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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lfx-self-serve: Skill for Claude Code