cpp-build

A command for diagnosing and fixing C++ build failures, including CMake configuration problems and linker errors. CMake is a tool that generates and manages build files for C++ projects.

In plain words
What is it for?
Use it when CMake builds fail, symbols are missing or defined more than once, templates fail to compile, includes are wrong, or a pulled change breaks the build.
Why use it?
It breaks a large build failure into smaller issues, applies minimal fixes, and checks the build after each change. This makes it easier to see which problems remain.

Command

Part of the muggle-ai-teams plugin — 28 commands, 29 agents shipped together

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 commands/multiplex-ai/muggle-ai-teams/cpp-build
Clone the repo
git clone --depth 1 https://github.com/multiplex-ai/muggle-ai-teams

Or install muggle-ai-teams, the plugin that ships this one along with the rest of its 28 commands, 29 agents.

Per session 30 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,053 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 $0.00030 $0.01053
Opus 5 $0.00015 $0.00526
Sonnet 5 $0.00006 $0.00211
Haiku 4.5 $0.00003 $0.00105

Measured 2d ago against content hash 61706136a28c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cpp-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 2d 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.

commands/cpp-build.md · 174 lines

How it starts

The opening of the file, as written. The whole thing — 174 lines — stays where its author put it; the contents beside it link to each section on GitHub.

C++ Build and Fix

This command invokes the cpp-build-resolver agent to incrementally fix C++ build errors with minimal changes.

What This Command Does

  1. Run Diagnostics: Execute cmake --build, clang-tidy, cppcheck
  2. Parse Errors: Group by file and sort by severity
  3. Fix Incrementally: One error at a time
  4. Verify Each Fix: Re-run build after each change
  5. Report Summary: Show what was fixed and what remains

When to Use

Use /cpp-build when:

  • cmake --build build fails with errors
  • Linker errors (undefined references, multiple definitions)
  • Template instantiation failures
  • Include/dependency issues
  • After pulling changes that break the build

Diagnostic Commands Run

# CMake configure
cmake -B build -S .

# Build
cmake --build build 2>&1 | head -100

# Static analysis (if available)
clang-tidy src/*.cpp -- -std=c++17
cppcheck --enable=all src/

Example Session

User: /cpp-build

Agent:
# C++ Build Resolution

## Initial Diagnostics

```bash
$ cmake --build build
src/service/user.cpp:25:15: error: use of undeclared identifier 'UserRepository'
src/handler/api.cpp:42:9: error: no matching function for call to 'process'
src/handler/api.cpp:58:1: error: non-void function does not return a value

Errors found: 3

Fix 1: Undeclared Identifier

File: src/service/user.cpp:25 Error: use of undeclared identifier 'UserRepository' Cause: Missing include

// Added include
#include "repository/user_repository.hpp"
$ cmake --build build
# 2 errors remaining

Fix 2: No Matching Function

File: src/handler/api.cpp:42 Error: no matching function for call to 'process'

// Changed
process(params.get("count"));
// To
process(std::stoi(params.get("count")));
$ cmake --build build
# 1 error remaining

Fix 3: Missing Return

File: src/handler/api.cpp:58 Error: non-void function does not return a value

std::optional<User> getUser(const std::string& id) {
    if (id.empty()) {
        return std::nullopt;
    }
    auto user = findUser(id);
    // Added missing return
    return user;
}
$ cmake --build build

Read the full file on GitHub · 174 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. 2d ago First seen · 174 lines · 30 tokens per session scan A 61706136a28c

Subscribe to this mod's changes

cpp-build is a command published in the GitHub repository multiplex-ai/muggle-ai-teams (2 stars, last pushed 3mo ago), licensed MIT. It adds 30 tokens to every session and 1,053 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 2026-08-31.