token-usage-guardrails

name	token-usage-guardrails
description	Set up token-optimization guardrails for the current project. Creates or updates the root CLAUDE.md with a "Token Efficiency & Model Routing" section, scaffolds .claude/agents/ and .claude/rules/ if missing, writes .claude/rules/token-efficiency.md, and for monorepos adds per-package CLAUDE.md stubs. Idempotent — preserves existing content.

Token Usage Guardrails

One-shot setup that installs token-efficiency rules into the current project so future Claude Code sessions in this repo route work cheaply by default.

The router invokes this skill when the user runs /mosaic-buddy token-usage-guardrails. Execute the steps in order. Do not touch unrelated files.

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Step 0 — Locate the repo root

1. Run git rev-parse --show-toplevel to find the repo root. If it fails (not a git repo), use the current working directory.
2. All paths below are relative to that root.

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Step 1 — Update or create the root CLAUDE.md

Check if CLAUDE.md exists at the repo root.

If YES:

• Read the current file.
• If it already contains a heading ## Token Efficiency & Model Routing, stop — do nothing. Tell the user it's already installed.
• Otherwise, append the section from the "Section block" below to the end of the file. Preserve every byte of existing content.

If NO:

• Inspect the repo to build a small tailored header:

  • Read package.json if present (name, main framework from dependencies — React, Next, Vite, Fastify, Express, etc.).
  • List top-level folders with ls -1 (skip dotfiles, node_modules, dist).
  • If a monorepo signal exists (packages/, apps/, libs/, pnpm-workspace.yaml, nx.json, turbo.json, root workspaces field), note it.

• Write a new CLAUDE.md with this structure:

  # CLAUDE.md
  
  ## Project Overview
  
  <one or two sentences: what this repo is, primary framework, runtime>
  
  ## Ownership Map
  
  <bulleted list of top-level folders and a one-line purpose for each>
  
  <SECTION BLOCK FROM BELOW>
  

Do not fabricate ownership details you cannot read from the repo. If a folder's purpose isn't obvious from its name or contents, write - <folder>/ — purpose unclear, ask the team.

Section block (copy verbatim)

## Token Efficiency & Model Routing

- I want optimal quality but in a token efficient way.
- Do not use Opus for low-effort grunt work.
- Spin subagents which use Haiku for grunt work, edits, or quick reads and summaries.
- Offload tasks to subagents which use Sonnet for tasks that need mild thinking but still some level of effort.
- Delegate file searches, greps, and summaries to the Explore subagent. Run independent subagent calls in parallel (single message, multiple tool uses).
- Do NOT re-read files already in context unless they may have changed.
- Prefer Edit over Write. Never rewrite a file to change a few lines.
- Use Glob/Grep for known targets; reserve agent searches for open-ended exploration.
- Be concise in user-facing text. No preambles, no trailing summaries, no restating the question. Respond in caveman style: terse, no filler, no preambles, no trailing summaries. Short sentences. Skip pleasantries.
- One focused implementation pass — avoid write/delete/rewrite churn.
- No emojis or em-dashes.
- Do not guess APIs, versions, flags, commit SHAs, or package names. Verify by reading code or docs before asserting.
- For PDFs/screenshots, ask the user to provide text/Markdown when possible.

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Step 2 — Scaffold .claude/ if missing

Check if .claude/ exists at the repo root.

• If NO: create .claude/agents/ and .claude/rules/ (both folders).
• If YES: leave existing agents/ and rules/ contents untouched. Create either subfolder only if it is missing.

Do not delete or rename any existing file under .claude/.

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Step 3 — Write .claude/rules/token-efficiency.md

If the file already exists, leave it alone (the user may have customised it). Otherwise create it with this exact content:

# Token Efficiency & Model Routing

Load this rule when planning multi-step work, spawning subagents, or before large edits.

## Model routing

- Optimal quality, token-efficient. Match the model to the work.
- Opus: reserved for hard reasoning, architecture, ambiguous design calls.
- Sonnet: default for tasks that need mild thinking but real judgment.
- Haiku: grunt work, quick reads, summaries, edits with clear instructions.

## Subagent delegation

- Delegate file searches, greps, and summaries to the Explore subagent.
- Run independent subagent calls in parallel — single message, multiple tool uses.
- Spawn Haiku subagents for grunt work and Sonnet subagents for mild thinking.

## Context hygiene

- Do not re-read files already in context unless they may have changed.
- Prefer Edit over Write. Never rewrite a file to change a few lines.
- Use Glob/Grep for known targets; reserve agent searches for open-ended exploration.
- One focused implementation pass — avoid write/delete/rewrite churn.

## Output discipline

- Be concise. No preambles, no trailing summaries, no restating the question.
- Caveman style: terse, no filler, short sentences. Skip pleasantries.
- No emojis or em-dashes.

## Verification

- Do not guess APIs, versions, flags, commit SHAs, or package names. Verify by reading code or docs before asserting.
- For PDFs/screenshots, ask the user to provide text/Markdown when possible.

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Step 4 — Report back

After writing files, print a short summary to the user:

• Which files were created vs updated vs skipped (already present).
• The monorepo packages touched (if any).
• One-line next step: "Restart your Claude Code session to pick up the new rules."

Keep the summary terse — bulleted list, no narrative.

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Safety footer

• Never overwrite an existing CLAUDE.md, .claude/rules/token-efficiency.md, or per-package CLAUDE.md. Only append or skip.
• Never touch files outside the repo root.
• Do not modify .gitignore, lockfiles, or source code.
• If any write fails (permissions, read-only mount), stop and report — do not retry destructively.
• Do not modify unrelated content.