claude-code-boilerplate: Agent for Claude Code

.claude/agents/principal-engineer.md

principal-engineer is an agent for Claude Code from levu304/claude-code-boilerplate. It costs 44 tokens per session (2,347 once invoked), scanned A, original, MIT.

A senior software-engineering reviewer for code quality, system design, and technical investigations.

In plain words
What is it for?
Use it to review architecture and implementation choices, investigate root causes, analyze errors and logs, and suggest focused improvements.
Why use it?
It helps identify hard-to-maintain code, design problems, hidden edge cases, technical debt, bugs, and performance issues.

Agent for Claude Code

Written for Claude Code: installed under .claude/. Also seen: model in frontmatter; mentions CLAUDE.md.

This is levu304/claude-code-boilerplate's own configuration. It tells Claude Code how to work on claude-code-boilerplate itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything claude-code-boilerplate configures →

Reuse

Borrowing it

Nothing to install: this file belongs to levu304/claude-code-boilerplate. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/levu304/claude-code-boilerplate/main/.claude/agents/principal-engineer.md
Clone the repo
git clone --depth 1 https://github.com/levu304/claude-code-boilerplate

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 principal-engineer

README.md
[![agentmods](https://agentmods.dev/badge/agents/levu304/claude-code-boilerplate/principal-engineer/github.svg)](https://agentmods.dev/agents/levu304/claude-code-boilerplate/principal-engineer)
Your own site
<a href="https://agentmods.dev/agents/levu304/claude-code-boilerplate/principal-engineer"><img src="https://agentmods.dev/badge/agents/levu304/claude-code-boilerplate/principal-engineer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for principal-engineer

Your own site · 80×15
<a href="https://agentmods.dev/agents/levu304/claude-code-boilerplate/principal-engineer"><img src="https://agentmods.dev/badge/agents/levu304/claude-code-boilerplate/principal-engineer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 44 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,347 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 $0.00044 $0.02347
Opus 5.5 $0.00018 $0.00939
Sonnet 5.5 $0.00009 $0.00469
Haiku 4.5 $0.00004 $0.00235

Measured 2mo ago against content hash c14afad5b0ac, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

principal-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 2mo 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/principal-engineer.md · 437 lines

How it starts

The opening of the file, as written. The whole thing — 437 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a principal software engineer with 15+ years of experience reviewing enterprise codebases and investigating complex technical issues.

STEP 1: Load Project Context (ALWAYS DO THIS FIRST)

Before any review or investigation:

  1. Read CLAUDE.md for project coding standards
  2. Read .claude/tech-stack.md (if exists) for technology reference
  3. Read .claude/docs/ for project-specific patterns
  4. Check the project's language and framework

Core Responsibilities

  1. Review code for quality, maintainability, and scalability
  2. Evaluate architecture and design patterns
  3. Check adherence to SOLID principles and clean code practices
  4. Identify technical debt and suggest refactoring opportunities
  5. Verify error handling and edge cases
  6. Assess code complexity and suggest simplifications
  7. Investigate technical issues, bugs, and performance problems
  8. Perform root cause analysis
  9. Debug complex issues across the stack
  10. Analyze logs, traces, and error reports

Investigation Process

1. Gather Information

Questions to Answer:

  • What is the exact issue or unexpected behavior?
  • When did it start occurring?
  • Is it reproducible? Steps to reproduce?
  • What is expected vs actual behavior?
  • Any error messages or stack traces?
  • Which environment(s) affected?

Commands to Run:

# Check recent changes
git log --oneline --since="3 days ago" --all

# Search for error messages in code
grep -r "error message" src/

# Check for related commits
git log --all --grep="related keyword"

2. Reproduce the Issue

# Run related tests
pnpm test -- "related-pattern"  # or pytest, go test, cargo test

# Run application locally
pnpm dev  # or python manage.py runserver, go run ., cargo run

# Document exact reproduction steps

3. Analyze Root Cause

For Backend Issues:

# Check API endpoint logic
grep -r "endpoint-path" src/

# Check database queries
grep -r "SELECT\|INSERT\|UPDATE" src/

# Check middleware/interceptors
grep -r "middleware\|interceptor" src/

# Check environment configuration
cat .env | grep "RELEVANT_VAR"

Read the full file on GitHub · 437 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. 2mo ago First seen · 437 lines · 44 tokens per session scan A c14afad5b0ac

Subscribe to this mod's changes

principal-engineer is an agent published in the GitHub repository levu304/claude-code-boilerplate (130 stars, last pushed 6mo ago), licensed MIT. It adds 44 tokens to every session and 2,347 once invoked, about $0.0002 per session on Opus 5.5. 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.

Related

Other agents, from other repositories

build-failure-analyst

Expert build-failure analyst for .NET / MSBuild repositories. Invoke when a build produced a binary log (.binlog) and you need to identify the root cause(s) of failure, group related errors, and propose concrete fixes. Queries the binlog live through the binlog-mcp MCP server (containerised — see the calling…

dotnet/skills · 108 tokens

swiftui-performance-analyzer

Use this agent when the user mentions SwiftUI performance, janky scrolling, slow animations, or view update issues — expensive bodies, formatters, whole-collection dependencies, and missing lazy containers.

CharlesWiltgen/Axiom · 45 tokens

review-obsidian-guidelines

Reviews a diff of obsidian-reminder against Obsidian's community plugin guidelines and directory review rules that ESLint does not already enforce — manifest metadata, command naming, settings UI, styling, mobile compatibility, vault access APIs. Used by the pr-review workflow; read-only.

uphy/obsidian-reminder · 63 tokens

predictive-analyst

Precognition agent. Analyzes code changes to predict impact, regressions, and conflicts BEFORE they happen. Uses dependency graphs and historical data.

softspark/ai-toolkit · 35 tokens

cognitive-judge

Code Review Court judge — debuggability at 3AM, naming, complexity, logs.

gonzalezpazmonica/savia · 23 tokens

silent-failure-hunter

Use this agent when reviewing code changes in a pull request to identify silent failures, inadequate error handling, and inappropriate fallback behavior. Invoke it after work involving error handling, catch blocks, fallback logic, or any code that could suppress errors. See "When to invoke" in the agent body for…

nota-america/forgecat-agent-profiles · 67 tokens