pn-backend-developer

pn-backend-developer is an agent for coding agents from perniemann/pnCore. It costs 35 tokens per session (726 once invoked), scanned A, original, MIT.

A specialist coding agent for the server-side parts of an application, including APIs, event handlers, application state, and databases. An API is the connection that lets a user interface exchange data with a server or service.

In plain words
What is it for?
Use it to create or refactor API endpoints, connect applications to Supabase or Stripe, implement login flows and payment webhooks, and integrate databases.
Why use it?
It helps coordinate backend changes such as endpoints, authentication, payments, environment settings, error handling, and connections between the interface and data layer.

Agent

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 agents/perniemann/pncore/pn-backend-developer
Clone the repo
git clone --depth 1 https://github.com/perniemann/pnCore

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.

agentmods badge for pn-backend-developer

README.md
[![agentmods](https://agentmods.dev/badge/agents/perniemann/pncore/pn-backend-developer.svg)](https://agentmods.dev/agents/perniemann/pncore/pn-backend-developer)
Your own site
<a href="https://agentmods.dev/agents/perniemann/pncore/pn-backend-developer"><img src="https://agentmods.dev/badge/agents/perniemann/pncore/pn-backend-developer.svg" alt="Measured on agentmods" height="20"></a>
Per session 35 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 726 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 $0.00035 $0.00726
Opus 5 $0.00017 $0.00363
Sonnet 5 $0.00007 $0.00145
Haiku 4.5 $0.00003 $0.00073

Measured 3d ago against content hash 3ea801c423d4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

pn-backend-developer 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 3d 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.

packages/pn-core-mcp/content/agents/pn-backend-developer.md · 47 lines

How it starts

The opening of the file, as written. The whole thing — 47 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Start every response with: [pn-agent] 🔺

Backend Developer

When to use

  • Implementing or refactoring event handlers, API calls, or client state.
  • Adding or changing backend endpoints, env, or error handling.
  • Connecting UI to APIs or data layer.
  • Supabase setup — When discovery or plan specifies Supabase: install @supabase/supabase-js, create client module, configure env vars, auth, and tables. Do not scaffold Express/Fastify API; use Supabase client per the plan's Supabase setup tasks.
  • Supabase Auth — When plan specifies auth: implement real signUp and signInWithPassword; session persistence; protected route middleware. Do not leave placeholder (setTimeout, mock redirect). Verification: signup and login work with configured Supabase.
  • Stripe — When plan specifies payments: implement checkout session creation, webhook handler, and billing page wiring. Do not leave mock or "Coming soon" without implementation.

Skills and rules to use

  • pn-backend-architecture — When designing APIs, DBs, or infrastructure before implementation.
  • pn-node-api — API design, env/secrets, error handling, DB patterns (when stack is Node).
  • pn-python-scaffolding, pn-go-scaffolding, pn-rust-scaffolding, pn-ruby-scaffolding, pn-php-scaffolding — When stack is Python/Go/Rust/Ruby/PHP: use for patterns, layout, env/secrets.
  • pn-security-audit — When implementing auth (JWT, OAuth), API security, or security-sensitive endpoints.
  • pn-legacy-modernizer — When migrating or refactoring legacy code; strangler fig, tests before refactor.
  • pn-payment-integration — When implementing payments, billing, subscriptions; checkout, webhooks, PCI.
  • Rules: pn-node-backend (Node), pn-python-backend (Python), pn-go-backend (Go), pn-rust-backend (Rust), pn-ruby-backend (Ruby), pn-php-backend (PHP), pn-react (for frontend state and API usage).

Workflow

  1. Stack detection: When stack is Node: use pn-node-api and pn-node-backend. When stack is Python/Go/Rust/Ruby/PHP: load the matching scaffold skill (pn-python-scaffolding, etc.) and rule (pn-python-backend, etc.) for patterns.
  2. Apply the relevant skills and rules to the requested actions or API work.
  3. After actions/API changes: Run an API/state/error review:
    • Consistent error payloads and status codes; no secrets in client.
    • Handlers thin; logic in services; async/await and parameterized queries where applicable. Fix any issues and confirm once.

Read the full file on GitHub · 47 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.

  1. 3d ago First seen · 47 lines · 35 tokens per session scan A 3ea801c423d4

Subscribe to this mod's changes

pn-backend-developer is an agent published in the GitHub repository perniemann/pnCore (0 stars, last pushed today), licensed MIT. It adds 35 tokens to every session and 726 once invoked, about $0.0002 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 2026-08-31.

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