closed-loop-development

closed-loop-development is a skill for Claude Code, Codex from Kevin-Liu-01/Agent-Machines. It costs 52 tokens per session (619 once invoked), scanned A, original, MIT.

A development workflow where the coding agent builds, runs, and checks software inside the same machine. It uses real services, endpoints, logs, browser behavior, databases, and tests to verify changes.

In plain words
What is it for?
Use it when building or debugging applications, testing APIs and user interfaces, checking database migrations, inspecting logs, and verifying that a change works end to end.
Why use it?
It removes the need for the user to act as the test harness by clicking through screens or copying back results. Failures can be observed and fixed in repeated development loops.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when building or debugging applications, testing APIs and user interfaces, checking database migrations, inspecting logs, and verifying that a change works end to end.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/kevin-liu-01/agent-machines/closed-loop-development
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.

Any agent
npx skills add Kevin-Liu-01/Agent-Machines --skill closed-loop-development
Clone the repo
git clone --depth 1 https://github.com/Kevin-Liu-01/Agent-Machines

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for closed-loop-development

README.md
[![agentmods](https://agentmods.dev/badge/skills/kevin-liu-01/agent-machines/closed-loop-development.svg)](https://agentmods.dev/skills/kevin-liu-01/agent-machines/closed-loop-development)
Your own site
<a href="https://agentmods.dev/skills/kevin-liu-01/agent-machines/closed-loop-development"><img src="https://agentmods.dev/badge/skills/kevin-liu-01/agent-machines/closed-loop-development.svg" alt="Measured on agentmods" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 619 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 2 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Excessive Agency · line 3
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
  • medium Rogue Agent · line 3
    Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.
    Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
How audits are shown
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 5.1 $0.00052 $0.00619
Opus 5 $0.00026 $0.00309
Sonnet 5 $0.00010 $0.00124
Haiku 4.5 $0.00005 $0.00062

Measured 8d ago against content hash bdcbafac4146, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

closed-loop-development scanned grade A with 1 finding 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 8d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- API: use `curl`, `httpx`, and `jq`. Hit the actual route. Save the exact response shape before changing client code around it.
knowledge/skills/closed-loop-development/SKILL.md · 46 lines

How it starts

The opening of the file, as written. The whole thing — 46 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Closed-Loop Development

Agent Machines are built so I can verify my own work. I should not ask the operator to click around, paste logs, or tell me what an endpoint returned when the machine can observe those things directly.

Default loop

  1. Read the repo instructions and identify the narrow behavior to change.
  2. Make the smallest useful edit.
  3. Start the relevant server, worker, or test target.
  4. Exercise the real surface with the right tool.
  5. Read failures from stdout, service logs, browser console, network traces, or database state.
  6. Fix the root cause and repeat until the observed behavior matches the requested behavior.

Tool choices

  • Browser/UI: use agent-browser or the browser_* toolset to navigate, snapshot, interact, screenshot, and inspect rendered UI. Snapshot before refs, and snapshot again after navigation or DOM changes.
  • API: use curl, httpx, and jq. Hit the actual route. Save the exact response shape before changing client code around it.
  • Database: use sqlite3 for local SQLite files and migration checks. Query the schema after running migrations.
  • Tests: use the repo-native runner first: node --test, npm test, pytest, go test, cargo test, or the project script.
  • Logs: inspect /.machine/logs/services/ first, then the runtime originals under /home/machine such as ~/.agent-machines/logs/gateway.log.
  • Network: use ss -tlnp, dig, curl -v, and nc to check listeners, DNS, and connection failures.
  • Runtime docs: read /.agent/llm.txt and /.agent/docs/agent-context.md before assuming which machine tools exist.

When to stop

Stop and report only when the blocker requires human ownership: missing credentials, captcha/passkey, destructive confirmation, provider outage, or an unavailable external system. Include what I tried, what I observed, and the next concrete manual step.

Anti-patterns

  • Asking "can you check the console?" when service logs or browser console tools exist.
  • Declaring success because code compiles while the endpoint or UI flow was never exercised.
  • Adding retries or fallbacks before proving the root cause.
  • Reinventing browser automation instead of using the installed browser tools.

Read the full file on GitHub · 46 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. 8d ago First seen · 46 lines · 52 tokens per session scan A bdcbafac4146

Subscribe to this mod's changes

closed-loop-development is a skill published in the GitHub repository Kevin-Liu-01/Agent-Machines (26 stars, last pushed 7d ago), licensed MIT. It adds 52 tokens to every session and 619 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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