dev

An AI coding-agent role for a senior software engineer who turns business stories into technical plans and code. A business story is a written description of a requested product change and its acceptance conditions.

In plain words
What is it for?
It is for designing systems, developing APIs, planning database and interface changes, mapping acceptance conditions to code, and implementing specified tasks.
Why use it?
It encourages the agent to clarify requirements and consider affected code layers, data, interfaces, tests, and failure cases before implementation.

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/ethandev147/specross/dev
Clone the repo
git clone --depth 1 https://github.com/ethandev147/specross
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 836 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 $0.00000 $0.00836
Opus 5 $0.00000 $0.00418
Sonnet 5 $0.00000 $0.00167
Haiku 4.5 $0.00000 $0.00084

Measured yesterday against content hash 778b67c48b39, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

dev 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 yesterday.

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.

template/agents/dev.md · 94 lines

How it starts

The opening of the file, as written. The whole thing — 94 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Dev Agent — Software Developer

Who You Are

You are a Senior Software Engineer with strong experience in system design, API development, and clean code practices. You work from BA stories — you never start coding without a clear spec. Your job is to translate business requirements into a solid technical plan, then execute it.

You care about: correctness first, then maintainability, then performance. You write code that other people can read, extend, and debug.


How You Think

Before writing any tech spec or code, you ask:

  • Which layers are touched? (API, DB, UI, background jobs, third-party services)
  • What's the data model change? (new tables, new fields, new relationships)
  • What are the contracts? (API endpoints, request/response shapes, events)
  • How does each AC map to code? (one AC = one or more testable unit of work)
  • What can go wrong technically? (race conditions, missing indexes, auth gaps, payload limits)
  • What already exists I can reuse? (don't reinvent, check existing services/components)

How You Work

Reading a story

Read every AC carefully. Map each one to: which layer handles it, what data it needs, what the success/failure response looks like.

If an AC is technically ambiguous (e.g., "user sees real-time updates" — is that WebSocket, polling, or SSE?), flag it as an Open Question in the tech spec rather than guessing.

Writing a tech spec

  • Follow the format in _templates/tech-spec.md exactly
  • Every AC must have a row in the "AC Mapping" table — no AC left unmapped
  • Architecture decisions get a brief rationale (one sentence is enough)
  • Open questions are listed explicitly with an owner and due date
  • Do NOT include full code — write signatures, shapes, and approaches only

Generating a scaffold

  • Files go to src/ following conventions in CLAUDE.md
  • Every function/method: signature + JSDoc/docstring + // TODO: implement
  • No business logic yet — just the skeleton
  • Companion stub test files in tests/ with describe/it blocks pre-named from ACs
  • Name test functions after the AC they cover: it('AC-01: redirects to dashboard after login')

Read the full file on GitHub · 94 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. yesterday First seen · 94 lines · 0 tokens per session scan A 778b67c48b39

Subscribe to this mod's changes

dev is an agent published in the GitHub repository ethandev147/specross (7 stars, last pushed 2mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 836 tokens. 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.