What is backend-building?

A backend add-on for an existing webapp-building frontend. It adds server routes, database support, authentication, and APIs using tRPC, Drizzle, Hono, MySQL, and OAuth 2.0.

Use it to add a database, API endpoints, authentication, and user management to a project already created with webapp-building.

It supplies the server-side parts a frontend needs to store data, expose API operations, and manage user sign-in. It is designed to add these parts without replacing the existing frontend files.

backend-building — Skill for Claude Code and Codex by serejaris

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo

git clone --depth 1 https://github.com/serejaris/kimi-skills

agentmods

npx agentmods add skills/serejaris/kimi-skills/backend-building

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/serejaris/kimi-skills/backend-building/github.svg)](https://agentmods.dev/skills/serejaris/kimi-skills/backend-building)

Your own site

<a href="https://agentmods.dev/skills/serejaris/kimi-skills/backend-building"><img src="https://agentmods.dev/badge/skills/serejaris/kimi-skills/backend-building/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/serejaris/kimi-skills/backend-building"><img src="https://agentmods.dev/badge/skills/serejaris/kimi-skills/backend-building.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 71 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 3,360 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	$0.00071	$0.03360
Opus 5.5	$0.00028	$0.01344
Sonnet 5.5	$0.00014	$0.00672
Haiku 4.5	$0.00007	$0.00336

Measured 2mo ago against content hash 0b50635dbd5f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

backend-building 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.

The scan reads SKILL.md. This mod also ships 37 executable files (scripts/.prepare-template.sh, scripts/init.sh, scripts/lib/merge-package-json.mjs, …), 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.

skills/backend-building/SKILL.md · 275 lines

How it starts

The opening of the file, as written. The whole thing — 275 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Backend Building

Stack: tRPC + Drizzle ORM + Hono + MySQL + OAuth 2.0

A backend-only skill that grafts onto an existing webapp-building project. It adds api/, contracts/ directories and optionally db/ — but never replaces or modifies existing frontend files.

Prerequisite: An existing project created by webapp-building.

Features

Features can be installed incrementally. Base infrastructure (Hono server, tRPC, contracts) is always installed automatically on first run.

Feature	What it provides	Dependencies
`db`	Drizzle ORM + MySQL — adds `db/`, `api/queries/connection.ts`, `drizzle.config.ts`	—
`auth`	Kimi OAuth + user management — adds `api/kimi/`, Login page, useAuth, AuthLayout	requires `db` (auto-included)

Default: init.sh "App" with no --features → defaults to auth (= db + auth), preserving backward compat.

Workflows

Frontend-first (recommended when UI is already built):

webapp-building init → develop UI pages and components
backend-building graft (this skill) — auto-wires tRPC providers and routes
Verify with npm run check, then add tRPC routers, database tables, wire frontend to API

Full-stack from scratch (recommended when backend is needed immediately):

webapp-building init → immediately graft backend-building
Verify with npm run check
Develop frontend and backend together

Incremental features (add capabilities over time):

Start with --features db for database only
Later add auth: init.sh "App" --features auth

Quick Start

1. Initialize Frontend First (webapp-building)

bash /app/.agents/skills/webapp-building/scripts/init-webapp.sh "My App"
cd /mnt/agents/output/app

2. Graft Backend

# Full stack with auth (default, same as before):
bash /app/.agents/skills/backend-building/scripts/init.sh "My App"

# Database only (no auth):
bash /app/.agents/skills/backend-building/scripts/init.sh "My App" --features db

# Add auth later:
bash /app/.agents/skills/backend-building/scripts/init.sh "My App" --features auth

Read the full file on GitHub · 275 lines

Files

What ships with it

60 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.

2mo ago First seen · 275 lines · 71 tokens per session scan A 0b50635dbd5f

Subscribe to this mod's changes

backend-building is a skill published in the GitHub repository serejaris/kimi-skills (11 stars, last pushed 3mo ago), licensed MIT. It adds 71 tokens to every session and 3,360 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 2026-08-31.

Backend and APIs Databases agent-skills ai-agents claude-skills kimi moonshot skills

backend-building next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
backend-buildingserejaris/kimi-skills	Skill	11	3mo ago	MIT	A	71	Claude Code, Codex
go-databasemuratmirgun/gophers	Skill	9	2mo ago	MIT	A	98	Claude Code
backend-setup-stackWESTsyre21/setup-backend-stack	Skill	4	4mo ago	MIT	A	155	Claude Code, Codex
backend-setup-stackWESTsyre21/setup-backend-stack	Skill	4	4mo ago	MIT	A	54	Claude Code, Codex
supabasesupabase/agent-skills	Skill	3.0k	yesterday	MIT	A	185	Claude Code, Codex
offensive-api-abuseSnailSploit/Claude-Red	Skill	10k	25d ago	MIT	B	184	Claude Code, Codex
511-frameworks-micronaut-jdbcjabrena/plinth	Skill	460	yesterday	Apache-2.0	A	118	Claude Code, Codex