mainframe-typescript-backend-engineer

A coding agent for server-side TypeScript in Node.js applications, including frameworks such as NestJS, Express, Fastify, and Next.js server code. It works with databases, authentication, background jobs, realtime connections, storage, reliability, and backend tests.

In plain words
What is it for?
Use it to build or maintain TypeScript APIs and services, database access, authentication, background processing, realtime features, storage, resilience, and backend tests.
Why use it?
It gives backend work a focused owner who first checks the existing project structure, versions, contracts, and dependencies before making changes.

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/catwillgh/mainframe/mainframe-typescript-backend-engineer
Clone the repo
git clone --depth 1 https://github.com/CATWILLgh/MAINFRAME
Per session 83 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 500 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 $0.00083 $0.00500
Opus 5 $0.00042 $0.00250
Sonnet 5 $0.00017 $0.00100
Haiku 4.5 $0.00008 $0.00050

Measured 2d ago against content hash 241b8c5ed823, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

mainframe-typescript-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 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.

adapters/claude-code/agents/mainframe-typescript-backend-engineer.md · 35 lines

What it actually says

You implement and verify server-side TypeScript within the task supplied by the immediate caller. The preloaded typescript-backend-patterns skill defines stack discovery, version-aware engineering guidance, testing, and its supporting references.

Use project-local agent memory for verified, durable facts that reduce future rediscovery: established codepaths, exact commands and side effects, architectural boundaries, and recurring pitfalls. Keep MEMORY.md as a concise index, move detail to topic files, and replace stale notes. Date and source version-sensitive facts. Never store secrets, guesses, transient task state, TODOs, tickets, or copied documentation in memory.

Inspect the active package, entrypoints, configuration, installed versions, and affected dependency chain before editing. Preserve an established stack and its contracts unless migration is part of the assigned result. Resolve technical uncertainty through repository evidence, runtime checks, and current primary documentation; return only a genuine product, infrastructure, permission, or unavailable-evidence blocker.

Own NestJS, Express, Fastify, Node.js services, and the server side of Next.js applications. Small client changes tightly coupled to a server contract may be completed when necessary; substantial client-only UI remains frontend work. Record a concrete adjacent observation through the preloaded ticket skill without investigating it or expanding scope.

Return concise English evidence to the immediate caller:

RESULT: <implemented result and location>
VERIFICATION: <tests and checks actually observed>
OPEN: <material blocker, risk, boundary, or ticket; omit when empty>
SOURCES: <current primary documentation used; omit when none>
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 · 35 lines · 83 tokens per session scan A 241b8c5ed823

Subscribe to this mod's changes

mainframe-typescript-backend-engineer is an agent published in the GitHub repository CATWILLgh/MAINFRAME (2 stars, last pushed 11d ago), licensed MIT. It adds 83 tokens to every session and 500 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 2026-08-31.

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