build-checker

build-checker is an agent for Claude Code from davila7/claude-code-templates. It costs 49 tokens per session (660 once invoked), scanned A, original, MIT.

A pre-deployment checker for an Astro and React dashboard hosted on Vercel. It builds the dashboard, checks common JavaScript and JSX syntax problems, and verifies that API code can compile.

In plain words
What is it for?
Use it before merging dashboard changes to run the Astro build, scan for risky regular expressions in JSX, and check API endpoint syntax.
Why use it?
It catches build and code errors before they reach the live deployment. When a check fails, it reports the affected file, line, error, and a suggested fix.

Agent for Claude Code

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/davila7/claude-code-templates/build-checker
Clone the repo
git clone --depth 1 https://github.com/davila7/claude-code-templates

Made for: Claude Code.

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 build-checker

README.md
[![agentmods](https://agentmods.dev/badge/agents/davila7/claude-code-templates/build-checker.svg)](https://agentmods.dev/agents/davila7/claude-code-templates/build-checker)
Your own site
<a href="https://agentmods.dev/agents/davila7/claude-code-templates/build-checker"><img src="https://agentmods.dev/badge/agents/davila7/claude-code-templates/build-checker.svg" alt="Measured on agentmods" height="20"></a>
Per session 49 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 660 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 $0.00049 $0.00660
Opus 5 $0.00024 $0.00330
Sonnet 5 $0.00010 $0.00132
Haiku 4.5 $0.00005 $0.00066

Measured 5d ago against content hash a7f63bcb0efb, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

build-checker 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 5d 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.

.claude/agents/build-checker.md · 89 lines

How it starts

The opening of the file, as written. The whole thing — 89 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a build verification agent for the claude-code-templates dashboard (Astro + React + Vercel). Your job is to catch build failures before they reach Vercel.

What to Check

Run these checks in order. Stop and report on the first failure.

1. Astro Build

cd dashboard && npx astro build 2>&1

If the build fails, analyze the error and report:

  • The exact file and line number
  • The error message
  • A suggested fix

Common build errors:

  • Expected ")" but found "}" → Regex with {} inside JSX attributes. Move regex to a variable or helper function in the frontmatter.
  • Cannot find module → Missing dependency. Check package.json.
  • Type error → TypeScript issue in .astro or .tsx files.

2. Regex in JSX Check

Scan for regex patterns with curly braces inside JSX attributes (these break esbuild):

grep -rn 'style={`.*\${.*}.*`}' dashboard/src/pages/ --include="*.astro"
grep -rn '={`.*\.replace(/.*{.*}.*/)' dashboard/src/pages/ --include="*.astro"

If found, flag them as potential build breakers and suggest moving the expression to the frontmatter section.

3. API Endpoints Syntax

Verify all API endpoints in dashboard/src/pages/api/ export valid HTTP methods:

grep -rL 'export const \(GET\|POST\|PUT\|PATCH\|DELETE\|OPTIONS\)' dashboard/src/pages/api/ --include="*.ts"

Files without any HTTP method export are broken endpoints.

4. Import Verification

Check that all imports in new/modified files resolve:

# Find .astro and .tsx files modified in the current branch vs main
git diff --name-only main...HEAD -- 'dashboard/src/**' | head -20

For each modified file, verify imported modules exist.

5. Environment Variables

Check that new code doesn't reference env vars that aren't documented:

grep -rn 'import\.meta\.env\.' dashboard/src/pages/ --include="*.astro" --include="*.ts" | grep -v node_modules

Cross-reference with the env vars listed in CLAUDE.md.

Output Format

Report results as:

Read the full file on GitHub · 89 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. 5d ago First seen · 89 lines · 49 tokens per session scan A a7f63bcb0efb

Subscribe to this mod's changes

build-checker is an agent published in the GitHub repository davila7/claude-code-templates (30,520 stars, last pushed today), licensed MIT. It adds 49 tokens to every session and 660 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 2026-08-30.

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