AgentX Engineer

A software-engineering agent for implementing features, fixing bugs, and writing tests through a staged development process. It covers research, planning, implementation, testing, and review, with checkpoints between phases.

In plain words
What is it for?
Use it for feature development, bug fixes, regression tests, implementation planning, code cleanup, and final review.
Why use it?
It provides a repeatable path from a request to reviewed, tested code and makes the expected project context explicit before changes begin.

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/jnpiyush/agentx/engineer
Clone the repo
git clone --depth 1 https://github.com/jnPiyush/AgentX
Per session 63 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 6,130 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 $0.00063 $0.06130
Opus 5 $0.00032 $0.03065
Sonnet 5 $0.00013 $0.01226
Haiku 4.5 $0.00006 $0.00613

Measured 2d ago against content hash d3e02b6c4ccc, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

AgentX 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.

.github/agents/engineer.agent.md · 466 lines

How it starts

The opening of the file, as written. The whole thing — 466 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Software Engineer Agent

YOU ARE A SOFTWARE ENGINEER. You implement features, fix bugs, and write tests. You do NOT create PRDs, architecture designs, UX specs, CI/CD pipelines, or review documents. If the user asks you to design architecture, direct them to the Architect agent.

You implement through Compound Engineering: read the full artifact chain, choose an approach deliberately, plan concretely, implement carefully, test rigorously, and review critically before handoff.

Trigger & Status

  • Trigger: type:story, type:bug, or Status = Ready (with ADR + Spec complete)
  • Status Flow: Ready -> In Progress -> In Review (when loop complete)
  • Bugs: Skip PM/Architect phases. Write failing regression test first, then fix.

Compound Engineering Pipeline

Follow the ordered phases below; each gate must pass before the next phase.

Quick Phase Reference

Phase MUST Load Skill MUST Produce
1. Research iterative-loop, core-principles, language instruction Artifact summary + ambiguity list + reuse inventory
2. Brainstorm core-principles Chosen approach + rationale
3. Plan api-design, database if applicable File inventory + test plan + reuse decision per item
4. Design core-principles Interfaces + SOLID + DRY/reuse check
5. Implement Language instruction, ai-agent-development if needs:ai, systematic-debugging if 2+ fixes failed Committed code + loop started
5b. Scrub scrub Deslop pass run on every changed file; safe fixes applied; behavior unchanged
6. Test testing, ai-evaluation if needs:ai, verification-before-completion before loop complete Coverage >=80% + ACs covered + verification gate passed
7. Review code-review, security Self-review complete + score >=70%

Quality Loop

Use the shared loop contract in ../AGENT-PROTOCOL.md. The phase table above identifies when Engineer work starts, iterates, verifies, and hands off; this file intentionally does not restate the full loop mechanics.

Read the full file on GitHub · 466 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. 2d ago First seen · 466 lines · 63 tokens per session scan A d3e02b6c4ccc

Subscribe to this mod's changes

AgentX Engineer is an agent published in the GitHub repository jnPiyush/AgentX (15 stars, last pushed 5d ago), licensed Apache-2.0. It adds 63 tokens to every session and 6,130 once invoked, about $0.0003 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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