rb:compound

A Ruby and Rails knowledge-capture tool for recording how a difficult problem was solved in a reusable YAML document.

In plain words
What is it for?
It is for documenting complex, multi-file problems, their causes, solutions, and reusable patterns.
Why use it?
It preserves debugging lessons and proven fixes so future work can reuse them instead of starting from scratch.

Skill for Claude CodeCodex

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 skills/slbug/claude-ruby-grape-rails/compound
Any agent
npx skills add slbug/claude-ruby-grape-rails --skill compound
Clone the repo
git clone --depth 1 https://github.com/slbug/claude-ruby-grape-rails

Made for: Claude Code, Codex.

Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,964 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 $0.00039 $0.01964
Opus 5 $0.00019 $0.00982
Sonnet 5 $0.00008 $0.00393
Haiku 4.5 $0.00004 $0.00196

Measured 2d ago against content hash 82e58b9c8c5e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

rb:compound 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.

plugins/ruby-grape-rails/skills/compound/SKILL.md · 283 lines

How it starts

The opening of the file, as written. The whole thing — 283 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Compound Knowledge

Capture a solved problem as reusable knowledge. This creates a knowledge base that helps future sessions solve similar problems faster.

What to Compound

Compound problems that:

  • Took significant time to solve (> 30 minutes)
  • Involved multiple files or systems
  • Required debugging or root cause analysis
  • Have reusable patterns or lessons
  • Others might encounter

Don't compound:

  • Trivial syntax errors
  • One-line fixes
  • Problems specific to unique project state
  • Already well-documented issues

Compound Process

START ──▶ VALIDATE AGAINST SCHEMA ──▶ USE RESOLUTION TEMPLATE ──▶ WRITE DOC
                                               │
                                               ▼
                                        UPDATE INDEX
                                               │
                                               ▼
                                             DONE

Document Structure

Solution documents use YAML frontmatter defined in ${CLAUDE_SKILL_DIR}/references/schema.md and follow the template in ${CLAUDE_SKILL_DIR}/references/resolution-template.md.

Required Frontmatter Fields

  • module: Ruby module or context area (e.g., "Accounts", "Hotwire/Turbo.UserList")
  • date: Creation date in YYYY-MM-DD format
  • problem_type: Category of problem (build_error, test_failure, runtime_error, etc.)
  • component: Affected component area (active_record_model, hotwire_mount, sidekiq_job, etc.)
  • symptoms: Array of 1-5 observable symptoms (error messages, unexpected behavior)
  • root_cause: Detailed explanation of WHY this happened
  • severity: critical, high, medium, or low
  • tags: Array of up to 8 searchable keywords (lowercase, hyphen-separated)

Optional Fields

  • ruby_version / rails_version: Specific version pattern X.Y.Z
  • iron_law_number: Integer (1-22) indicating which Iron Law was violated
  • related_solutions: Array of file paths to related solutions

Example Compound Document

Read the full file on GitHub · 283 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 283 lines · 39 tokens per session scan A 82e58b9c8c5e

Subscribe to this mod's changes

rb:compound is a skill published in the GitHub repository slbug/claude-ruby-grape-rails (7 stars, last pushed 3d ago), licensed MIT. It adds 39 tokens to every session and 1,964 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.