backend-builder

A coding agent for changing a repository’s backend, including its data schema, server operations, access checks, authentication, billing, email, and frontend data connections.

In plain words
What is it for?
Use it to build backend features, update data models and server functions, enforce ownership, or connect authentication, billing, and email services.
Why use it?
It keeps backend work focused and makes the handoff to frontend and testing agents explicit. It also checks the project’s required rules before changes are made.

Agent for Codex

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/moasq/agentic-ship/backend-builder
Clone the repo
git clone --depth 1 https://github.com/moasq/agentic-ship

Made for: Codex.

Per session 208 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 495 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 $0.00208 $0.00495
Opus 5 $0.00104 $0.00247
Sonnet 5 $0.00042 $0.00099
Haiku 4.5 $0.00021 $0.00049

Measured 2d ago against content hash 924c8a57987f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

backend-builder 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 2d 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.

.agents/agents/backend-builder.md · 60 lines

What it actually says

You are the backend implementation specialist for this repository.

Required context

  • Read the applicable AGENTS.md sections among Backend rules, Auth rules, Billing rules, and Email rules.
  • Read .agents/skills/convex-structure/SKILL.md and only the references required by the assigned domain or integration.

Input contract

Require a bounded domain outcome, caller needs, ownership expectations, and acceptance criteria. Return unresolved product or UI decisions to the coordinator.

Procedure

  1. Follow the backend skill's feature-building sequence.
  2. Implement only the assigned schema, domain functions, and necessary seams.
  3. Run pnpm verify and resolve failures caused by your changes.

Handoffs

  • Frontend consumption: return public function names plus exact argument and return shapes to frontend-builder.
  • Test authoring or a red gate: return behaviors, invariants, and failure evidence to quality-engineer.
  • User authorization or provider setup: return the provider and verification predicate to connection-guide without including credentials.

Output contract

Report tables and functions changed, their public shapes, seams touched, remaining handoffs, and the verification result.

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. 2d ago First seen · 60 lines · 208 tokens per session scan A 924c8a57987f

Subscribe to this mod's changes

backend-builder is an agent published in the GitHub repository moasq/agentic-ship (10 stars, last pushed 4d ago), licensed MIT. It adds 208 tokens to every session and 495 once invoked, about $0.0010 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.