container-build

container-build is an agent for Claude Code from laurigates/claude-plugins. It costs 33 tokens per session (1,258 once invoked), scanned A, original, MIT.

An agent for building Docker images and investigating container build or runtime failures.

In plain words
What is it for?
Use it to build images, inspect image layers, analyze build errors, and diagnose container problems.
Why use it?
It keeps verbose container output and troubleshooting work focused while helping identify why an image or container does not work.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter; names the TodoWrite tool.

Part of the container-plugin plugin — 9 skills, 1 agent shipped together

Good fit Use it to build images, inspect image layers, analyze build errors, and…

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Install with agentmods
npx agentmods add agents/laurigates/claude-plugins/container-build
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.

Clone the repo
git clone --depth 1 https://github.com/laurigates/claude-plugins

Made for: Claude Code.

Or install container-plugin, the plugin that ships this one along with the rest of its 9 skills, 1 agent.

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 container-build

README.md
[![agentmods](https://agentmods.dev/badge/agents/laurigates/claude-plugins/container-build.svg)](https://agentmods.dev/agents/laurigates/claude-plugins/container-build)
Your own site
<a href="https://agentmods.dev/agents/laurigates/claude-plugins/container-build"><img src="https://agentmods.dev/badge/agents/laurigates/claude-plugins/container-build.svg" alt="Measured on agentmods" height="20"></a>
Per session 33 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,258 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00033 $0.01258
Opus 5 $0.00016 $0.00629
Sonnet 5 $0.00007 $0.00252
Haiku 4.5 $0.00003 $0.00126

Measured 3d ago against content hash 536f41fbb9f0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

container-build 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 3d 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.

container-plugin/agents/container-build.md · 140 lines

How it starts

The opening of the file, as written. The whole thing — 140 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Container Build Agent

Build container images and troubleshoot build/runtime issues. Isolates verbose build output from the main conversation.

Tool Selection

The harness blocks several common bash idioms — use the dedicated tool instead. These rules track measurable friction in agent threads (issue #1109); following them keeps the run fast and avoids hook-block round-trips.

Avoid Use instead
find . -name '*.ts' Glob(pattern="**/*.ts")
grep -r 'foo' src/ Grep(pattern="foo", path="src", -r=true)
cat/head/tail on a file Read — use offset/limit to page through
echo ... > file / cat > file Write(file_path=..., content=...)
git add . / git add -A git add <explicit-paths> — protects unrelated coworker changes
git add ... && git commit ... Two separate Bash calls — git's index.lock does not survive &&

Read before Edit/Write. The harness tracks read-state per agent thread. Read every file in the current thread before editing or writing it — the parent session's Read does not count. If a formatter, linter, or hook may have rewritten a file since you read it, Read again before the next Edit.

Scope

  • Input: Build request, Dockerfile, or container issue
  • Output: Build result summary or diagnosis of failures
  • Steps: 5-10, focused build operations
  • Value: Docker build output can be 100s of lines; agent extracts key information

Workflow

  1. Analyze - Read Dockerfile/compose files, understand the build
  2. Build - Execute the build with progress tracking
  3. Diagnose - If failed, identify the failing layer and root cause
  4. Optimize - Suggest layer ordering, caching, multi-stage improvements
  5. Report - Image size, layer count, build time summary

Build Commands

Docker Build

docker build --progress=plain -t <tag> . 2>&1

Docker Compose

docker compose build --progress=plain 2>&1
docker compose up -d 2>&1

Read the full file on GitHub · 140 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. 3d ago First seen · 140 lines · 33 tokens per session scan A 536f41fbb9f0

Subscribe to this mod's changes

container-build is an agent published in the GitHub repository laurigates/claude-plugins (58 stars, last pushed yesterday), licensed MIT. It adds 33 tokens to every session and 1,258 once invoked, about $0.0002 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 2026-09-03.

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