backend-engineer

backend-engineer is a skill for Claude Code, Codex from wasintoh/toh-framework. It costs 75 tokens per session (3,661 once invoked), scanned A, original, MIT.

A specialist for connecting an existing user interface to Supabase, a hosted service for databases, user accounts, file storage and live data updates. It works after the interface has been built with sample data.

In plain words
What is it for?
Use it to add a database, login, real-time updates or storage to an existing UI, including the required client setup, database structure, queries and access policies.
Why use it?
It replaces sample data with real stored data without redesigning the interface or adding unrelated features. It also sets up access rules so users can only reach permitted data.

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/wasintoh/toh-framework/backend-engineer
Any agent
npx skills add wasintoh/toh-framework --skill backend-engineer
Clone the repo
git clone --depth 1 https://github.com/wasintoh/toh-framework

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.

agentmods badge for backend-engineer

README.md
[![agentmods](https://agentmods.dev/badge/skills/wasintoh/toh-framework/backend-engineer.svg)](https://agentmods.dev/skills/wasintoh/toh-framework/backend-engineer)
Your own site
<a href="https://agentmods.dev/skills/wasintoh/toh-framework/backend-engineer"><img src="https://agentmods.dev/badge/skills/wasintoh/toh-framework/backend-engineer.svg" alt="Measured on agentmods" height="20"></a>
Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,661 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 $0.00075 $0.03661
Opus 5 $0.00037 $0.01831
Sonnet 5 $0.00015 $0.00732
Haiku 4.5 $0.00007 $0.00366

Measured 4d ago against content hash bca4448d605e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

backend-engineer 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 4d 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.

src/skills/backend-engineer/SKILL.md · 617 lines

How it starts

The opening of the file, as written. The whole thing — 617 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Backend Engineer

Connect beautiful UI to real data. Supabase-first approach.

<core_principle>

The Integration Promise

Working UI with mock data → Connect Supabase → Real data flows automatically

We DON'T redesign. We DON'T add features. We connect what exists. </core_principle>

<default_to_action> NEVER ask:

  • "Which database should I use?" → Supabase (our standard)
  • "What's the schema?" → Derive from existing TypeScript types
  • "What type of auth do you need?" → Supabase Auth with social providers

ALWAYS do:

  • Create Supabase client configuration
  • Generate schema from existing types
  • Setup RLS policies
  • Replace mock API calls with Supabase queries </default_to_action>

<supabase_setup>

Initial Setup

1. Install Dependencies

npm install @supabase/supabase-js

2. Environment Variables

# .env.local
NEXT_PUBLIC_SUPABASE_URL=https://xxxxx.supabase.co
NEXT_PUBLIC_SUPABASE_ANON_KEY=eyJhbGc...

3. Client Configuration

// src/lib/supabase.ts
import { createClient } from '@supabase/supabase-js'
import { Database } from '@/types/supabase'

const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL!
const supabaseKey = process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!

export const supabase = createClient<Database>(supabaseUrl, supabaseKey)

4. Type Generation (after creating tables)

npx supabase gen types typescript --project-id xxxxx > src/types/supabase.ts

</supabase_setup>

<schema_patterns>

Database Schema Patterns

Derive from TypeScript Types

// Existing type from dev-engineer
interface Product {
  id: string
  name: string
  description: string
  price: number
  stock: number
  category: string
  isActive: boolean
  createdAt: Date
  updatedAt: Date
}

// Becomes SQL
-- SQL for Supabase
create table products (
  id uuid default gen_random_uuid() primary key,
  name text not null,
  description text,
  price decimal(10,2) not null default 0,
  stock integer not null default 0,
  category text not null,
  is_active boolean not null default true,
  created_at timestamp with time zone default now(),
  updated_at timestamp with time zone default now()
);

-- Auto-update updated_at
create or replace function update_updated_at()
returns trigger as $$
begin
  new.updated_at = now();
  return new;
end;
$$ language plpgsql;

create trigger products_updated_at
  before update on products
  for each row execute function update_updated_at();

Read the full file on GitHub · 617 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. 4d ago First seen · 617 lines · 75 tokens per session scan A bca4448d605e

Subscribe to this mod's changes

backend-engineer is a skill published in the GitHub repository wasintoh/toh-framework (95 stars, last pushed yesterday), licensed MIT. It adds 75 tokens to every session and 3,661 once invoked, about $0.0004 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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