94% fewer tokens: where Headroom wins (and where it doesn't)

# Generates the scratch shop-api bench (run inside the repo dir). Seeded, deterministic.
import json, random, datetime, math, os
for d in ('config', 'test', 'logs', 'src'): os.makedirs(d, exist_ok=True)
random.seed(7)
words=["SPRING","SUMMER","FALL","WINTER","VIP","WELCOME","FLASH","CYBER","BLACK","LOYAL","STUDENT","BDAY","FRIEND","APP","EMAIL","HOLIDAY","NEW","BACK","TEAM","GIFT"]
pcts=[5,10,15,20,25,30,40,50]; sufx=["","A","B","X","26","NY","LA"]
allc=[w+str(p)+s for w in words for p in pcts for s in sufx]
random.shuffle(allc)
codes=[]
for c in allc[:900]:
    if c=="FALL25": continue
    codes.append({"code":c,"percent":random.choice(pcts),"active":random.random()>0.25,
      "created":f"2026-{random.randint(1,9):02d}-{random.randint(1,28):02d}","owner":random.choice(["growth","crm","retail","partnerships","support"]),
      "min_subtotal":random.choice([0,0,25,50,100]),"max_uses":random.choice([100,500,1000,5000,None]),"uses":random.randint(0,4000),
      "channels":random.sample(["web","ios","android","pos","email"],k=random.randint(1,4)),"notes":random.choice(["","seasonal","partner campaign","do not extend","migrated from v1"])})
codes.insert(617,{"code":"FALL25","percent":"25%","active":True,"created":"2026-10-14","owner":"growth","min_subtotal":0,"max_uses":5000,"uses":1843,"channels":["web","ios","android"],"notes":"fall campaign, imported from sheet"})
json.dump({"version":42,"updated":"2026-10-14T09:12:44Z","codes":codes},open("config/discounts.json","w"),indent=2)
act=[c for c in codes if c["active"] and c["code"]!="FALL25"]
L=["import { test } from 'node:test';","import assert from 'node:assert/strict';","import { checkoutTotal, applyDiscount } from '../src/pricing.js';",""]
for i in range(600):
    c=random.choice(act); sub=round(random.uniform(5,400),2)
    exp=math.floor(sub*(1-c["percent"]/100)*100+0.5)/100
    L.append(f"test('discount {c['code']} on {sub}', () => {{ assert.equal(applyDiscount({sub}, '{c['code']}'), {exp}); }});")
L+=["test('checkout with FALL25 (fall campaign)', () => {","  const total = checkoutTotal([{ price: 40, qty: 2 }, { price: 19.99, qty: 1 }], 'FALL25');","  assert.equal(total, 80.99);","});"]
for i in range(40):
    c=random.choice(act)
    L.append(f"test('checkout {i} with {c['code']}', () => {{ assert.ok(checkoutTotal([{{ price: 10, qty: {i+1} }}], '{c['code']}') > 0); }});")
open("test/pricing.test.js","w").write("\n".join(L)+"\n")
t=datetime.datetime(2026,10,14,6,0,0); out=[]
paths=["/api/cart","/api/products","/api/checkout","/api/user","/api/search","/healthz"]
for i in range(20000):
    t+=datetime.timedelta(milliseconds=random.randint(200,1500))
    rid="%08x"%random.getrandbits(32); p=random.choice(paths)
    if p=="/api/checkout" and t>datetime.datetime(2026,10,14,9,13) and random.random()<0.35:
        out.append(f"{t.isoformat()}Z ERROR req={rid} POST /api/checkout 500 code=FALL25 err=\"checkout total is NaN\" ms={random.randint(3,30)}")
    else:
        lvl=random.choices(["INFO","DEBUG","WARN"],[70,25,5])[0]
        st=200 if lvl!="WARN" else random.choice([404,429])
        out.append(f"{t.isoformat()}Z {lvl} req={rid} {random.choice(['GET','POST'])} {p} {st} ms={random.randint(2,400)} ua=\"{random.choice(['ios/5.2','android/5.1','web/chrome','web/safari'])}\" region={random.choice(['us-east','us-west','eu-west'])}")
open("logs/app.log","w").write("\n".join(out)+"\n")

import { readFileSync } from 'node:fs';

const discounts = JSON.parse(readFileSync(new URL('../config/discounts.json', import.meta.url)));

export function findDiscount(code) {
  if (!code) return null;
  return discounts.codes.find((d) => d.code === code.toUpperCase() && d.active) || null;
}

export function applyDiscount(subtotal, code) {
  const d = findDiscount(code);
  if (!d) return subtotal;
  const pct = Number(d.percent);
  return Math.round(subtotal * (1 - pct / 100) * 100) / 100;
}

export function checkoutTotal(items, code, taxRate = 0.08) {
  const subtotal = items.reduce((s, it) => s + it.price * it.qty, 0);
  const discounted = applyDiscount(subtotal, code);
  const total = Math.round(discounted * (1 + taxRate) * 100) / 100;
  if (Number.isNaN(total)) throw new Error('checkout total is NaN');
  return total;
}

{
  "name": "shop-api",
  "version": "1.4.2",
  "private": true,
  "type": "module",
  "scripts": { "test": "node --test --test-reporter=spec" }
}

#!/bin/bash
# A/B: plain Claude Code vs `headroom wrap claude`, 3 runs each, interleaved, same prompt.
# Needs: claude (Claude Code), headroom (uv tool install --python 3.13 "headroom-ai[all]"), node, a pristine copy of the bench in ./pristine
Q='Checkout has been failing for some customers since Oct 14 and npm test is red. Use the test output and logs/app.log to find the root cause, fix it properly, and make npm test pass. Finish with a two-line summary of the cause and the fix.'
export HEADROOM_BEACON=off DO_NOT_TRACK=1
for n in 1 2 3; do
  rm -rf runs/direct-$n runs/wrap-$n; mkdir -p runs
  cp -R pristine runs/direct-$n; (cd runs/direct-$n && claude -p --model claude-sonnet-5-5 --allowedTools "Bash Read Edit Write Grep Glob" --output-format json "$Q" < /dev/null > ../direct-$n.json)
  cp -R pristine runs/wrap-$n;   (cd runs/wrap-$n && headroom wrap claude --code-memory none -- -p --model claude-sonnet-5-5 --allowedTools "Bash Read Edit Write Grep Glob mcp__headroom__headroom_retrieve" --output-format json "$Q" < /dev/null > ../wrap-$n.json)
done
# input tokens = usage.input_tokens + cache_creation_input_tokens + cache_read_input_tokens; cost = total_cost_usd
headroom unwrap claude

# pip install "headroom-ai[all]"   (run with HEADROOM_BEACON=off)
from headroom import compress
log = open('slice.log').read()          # 2,500 lines around the first error in logs/app.log
msgs = [{"role": "user", "content": "why did checkout fail?"},
        {"role": "assistant", "content": [{"type": "tool_use", "id": "t1", "name": "Bash", "input": {"command": "cat slice.log"}}]},
        {"role": "user", "content": [{"type": "tool_result", "tool_use_id": "t1", "content": log}]}]
r = compress(msgs, model="claude-sonnet-5-5")
print(r.tokens_before, '->', r.tokens_before - r.tokens_saved)   # we got 112,029 -> 4,310