cost-audit

name	cost-audit
description	Analyzes the current session's token usage, pinpoints where tokens were wasted, and produces concrete optimization actions
user-invocable	true
allowed-tools	Bash(claude*), Read, Grep
effort	low

Goal

Make it visible where the tokens in this session actually went. Not guesses — evidence. Output: "do these 3 things next time and you save ~X%."

Step 1 — Capture current cost

/cost

Note the output: total tokens, input/output split, cache hit rate, total $.

Step 2 — Find the leaks

Scan the transcript for these signals:

Signal	How to detect it	Why it wastes tokens
Unnecessary file reads	Read calls touching node_modules/, dist/, *.lock, coverage/	Missing .claudeignore
Re-reading the same file	Same path appears in multiple Read calls	Context lost — /compact should have happened earlier
Reading entire large files	Read without limit on files >500 lines	Should have used offset/limit or Grep
Bash + grep/cat/find	Bash calls to grep, cat, find, ls -R	Dedicated tools (Grep/Glob/Read) are cheaper and more precise
Vague prompt → many tool calls	Single-word asks ("improve", "fix", "look") followed by 5+ tool calls	Prompt wasn't specific
Repeated onboarding research	Same concept re-discovered across sessions	Belongs in CLAUDE.md

Step 3 — Report

Give the user a report in this shape:

## Session summary
- Total: <tokens> (<$>)
- Cache hit: <%>

## Top 3 leaks
1. [Evidence]: X files under src/components/ were read in full; ~Y tokens combined
   Fix: add to .claudeignore → <lines>
   Estimated savings: ~Z%

2. ...

3. ...

## Action list
- [ ] Create .claudeignore with <lines>
- [ ] Add a "<topic>" section to CLAUDE.md
- [ ] Use `/compact <hint>` earlier in long sessions

Step 4 — Optional auto-fixes

If the user approves:

• Create .claudeignore if missing, add the detected paths
• Create a CLAUDE.md scaffold if missing, seed it with the repeated-research topics
• Suggest a specific /compact hint phrase for this project

Rules

• No guessing — only report what's in the transcript
• Always a number — not "a lot", but "12,400 tokens"
• Action-oriented — every finding ends with a concrete command or edit
• Keep it short — 3 top leaks is plenty; skip the long tail