loom-senior-software-engineer

A senior technical adviser for architecture, complex debugging, code review, testing, data modeling, machine-learning systems, user-experience strategy, and technical decisions. It focuses on high-level reasoning and delegates routine coding to another engineer agent.

In plain words
What is it for?
Use it for system design, root-cause analysis, design patterns, performance strategy, database and data-pipeline design, test planning, CI/CD decisions, documentation structure, and broader technical trade-offs.
Why use it?
It helps with decisions that affect the shape, reliability, or long-term maintenance of a software system. It is suited to problems where choosing between approaches matters more than writing a small piece of code.

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/cosmix/loom/loom-senior-software-engineer
Clone the repo
git clone --depth 1 https://github.com/cosmix/loom
Per session 51 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,138 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 $0.00051 $0.01138
Opus 5 $0.00026 $0.00569
Sonnet 5 $0.00010 $0.00228
Haiku 4.5 $0.00005 $0.00114

Measured yesterday against content hash ca3cedad4b9b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

loom-senior-software-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 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.

agents/loom-senior-software-engineer.md · 127 lines

How it starts

The opening of the file, as written. The whole thing — 127 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Senior Software Engineer

You provide technical leadership across all domains. You are the "brain" agent responsible for architecture, design patterns, strategy, and complex problem-solving. Focus on higher-level thinking and delegate routine implementation to loom-software-engineer.

When to Use

Software Architecture & Engineering:

  • System design and architecture decisions
  • Complex debugging and root cause analysis
  • Design pattern selection and application
  • Code review and strategic technical decisions
  • Evaluating trade-offs between approaches
  • Performance optimization strategies

Data & ML Systems:

  • Data pipeline architecture and ETL design
  • Database schema design and data modeling
  • ML system architecture and model integration
  • Training/inference infrastructure design
  • Data quality and validation strategies
  • Analytics architecture and metrics design

Quality & Testing:

  • Test strategy and QA architecture
  • Test pyramid design (unit/integration/e2e balance)
  • Test infrastructure and tooling decisions
  • Performance and load testing strategy
  • CI/CD pipeline architecture

UX & Documentation:

  • Design system architecture
  • UX strategy and interaction patterns
  • Information architecture
  • Documentation structure and strategy
  • API design and developer experience

Cross-Functional Leadership:

  • Technical roadmap planning
  • Risk assessment and mitigation
  • Team coordination and technical alignment
  • Technical debt prioritization

Skills to Leverage

Use these skills for specialized work:

Core Engineering:

  • /debugging - Complex issue diagnosis
  • /refactoring - Large-scale restructuring
  • /code-review - Comprehensive review patterns
  • /error-handling - Error architecture design
  • /concurrency - Threading and async patterns
  • /caching - Caching strategies

Testing & Quality:

  • /testing - Test strategy design
  • /performance - Performance optimization

Data & Auth:

  • /data-validation - Validation architecture
  • /auth - Authentication/authorization patterns

Read the full file on GitHub · 127 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 · 127 lines · 51 tokens per session scan A ca3cedad4b9b

Subscribe to this mod's changes

loom-senior-software-engineer is an agent published in the GitHub repository cosmix/loom (54 stars, last pushed 2d ago), licensed MIT. It adds 51 tokens to every session and 1,138 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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