receipts: show a sample receipt in the README

You can't tell what this produces from a description, and the obvious
way to show it — screenshot a real run — would put someone's actual
repo names in a public README.

So the sample is generated: assets/make-sample.mjs builds a throwaway
HOME of invented repos, invented files and invented sessions, and the
real miner runs against that. The picture is what the tool genuinely
produces, from data that never existed. Checked the output and the
generator for anything real; the PNG carries no metadata chunks.

Keeping the generator next to the asset so the next person can
regenerate it rather than hand-editing a screenshot.

No-Verification-Needed: docs asset + dev-only generator, no plugin runtime surface

plugins/receipts/README.md

@@ -4,6 +4,12 @@ Generate a personal Claude Code impact report — "receipts" — from your own
 session transcripts, for the conversation where someone asks what all this
 Claude Code usage is actually buying.
 
+<img src="assets/sample-receipt.png" width="400"
+  alt="A printed-receipt-styled report headed 'Claude Code — usage receipt, Morgan Lunt', covering 2026-06-21 to 2026-07-20, active on 28 of 30 days. It lists 40 sessions, 64 prompts, 14 files touched, 3,120 lines touched, 12 commits carrying that work and 7 PRs opened, headlined as 19 commits and PRs shipped. A by-project table gives 'Research and investigation (no project)' 53% of spend with no files touched, then acme-api 29%, acme-web 10%, billing-service 5%, infra-terraform 3%, and a plain ~/notes directory 1%. Footnotes explain which columns do not sum, and an Export CSV button sits above a barcode.">
+
+*Sample output — the projects and numbers are invented. It's rendered from a
+synthetic corpus, not from anyone's real usage.*
+
 ## Install
 
 ```

plugins/receipts/assets/make-sample.mjs

@@ -0,0 +1,183 @@
+// make-sample.mjs — regenerate assets/sample-receipt.png for the README.
+//
+// The README's sample must never contain anyone's real projects, so it isn't a
+// screenshot of a real run. This builds a throwaway HOME with invented repos,
+// invented files and invented sessions, then points the real miner at it — the
+// picture is genuinely what the tool produces, from data that never existed.
+//
+//   node assets/make-sample.mjs ~/receipts-sample
+//   HOME=~/receipts-sample/home node skills/receipts/scripts/mine-transcripts.mjs \
+//     --days 30 --html /tmp/sample.html
+//   # screenshot /tmp/sample.html at 620px wide, crop to the receipt
+//
+// Build it somewhere with no symlink above it — NOT /tmp, which on macOS is a
+// symlink to /private/tmp. `git rev-parse --show-toplevel` resolves symlinks
+// and these transcripts don't, so under /tmp every repo reports zero commits
+// and the sample comes out silently wrong.
+//
+// Keep the invented names obviously fake (acme-*, example.com).
+
+import fs from 'node:fs';
+import path from 'node:path';
+import { execFileSync } from 'node:child_process';
+
+const ROOT = process.argv[2];
+const HOME = path.join(ROOT, 'home');
+fs.rmSync(ROOT, { recursive: true, force: true });
+
+const NAME = 'Morgan Lunt';
+const EMAIL = 'morgan@example.com';
+
+const git = (cwd, ...a) => execFileSync('git', ['-C', cwd, ...a], { stdio: ['ignore', 'pipe', 'ignore'] });
+
+// --- invented projects -------------------------------------------------------
+const REPOS = {
+  'acme-api': ['src/routes/orders.ts', 'src/routes/refunds.ts', 'src/db/schema.sql', 'src/lib/auth.ts', 'tests/orders.test.ts'],
+  'acme-web': ['app/checkout/page.tsx', 'app/cart/state.ts', 'components/PriceTag.tsx'],
+  'billing-service': ['internal/invoice/render.go', 'internal/tax/rates.go'],
+  'infra-terraform': ['envs/prod/main.tf', 'modules/rds/variables.tf'],
+};
+const NOTES = ['migration-plan.md', 'oncall-runbook.md'];
+
+fs.mkdirSync(path.join(HOME, 'notes'), { recursive: true });
+fs.writeFileSync(path.join(HOME, '.gitconfig'), `[user]\n\tname = ${NAME}\n\temail = ${EMAIL}\n`);
+for (const f of NOTES) fs.writeFileSync(path.join(HOME, 'notes', f), 'note\n'.repeat(40));
+
+for (const [repo, files] of Object.entries(REPOS)) {
+  const dir = path.join(HOME, 'code', repo);
+  fs.mkdirSync(dir, { recursive: true });
+  git(dir, 'init', '-q', '-b', 'main');
+  git(dir, 'config', 'user.name', NAME);
+  git(dir, 'config', 'user.email', EMAIL);
+  git(dir, 'config', 'commit.gpgsign', 'false');
+  for (const f of files) {
+    fs.mkdirSync(path.dirname(path.join(dir, f)), { recursive: true });
+    fs.writeFileSync(path.join(dir, f), 'x\n'.repeat(60));
+  }
+  git(dir, 'add', '-A');
+  git(dir, 'commit', '-qm', 'initial');
+}
+
+// --- invented transcripts ----------------------------------------------------
+const PROJ = path.join(HOME, '.claude', 'projects', 'sample');
+fs.mkdirSync(PROJ, { recursive: true });
+
+let uid = 0;
+const U = () => `u${++uid}`;
+const day = (back) => {
+  const d = new Date();
+  d.setDate(d.getDate() - back);
+  d.setHours(10 + (back % 6), 15, 0, 0);
+  return d.toISOString();
+};
+const usage = (out) => ({
+  input_tokens: 900,
+  output_tokens: out,
+  cache_creation: { ephemeral_5m_input_tokens: 4000, ephemeral_1h_input_tokens: 0 },
+  cache_read_input_tokens: 30000,
+});
+const asst = (sid, ts, cwd, blocks, out = 300) => ({
+  type: 'assistant', sessionId: sid, uuid: U(), requestId: `r${uid}`, timestamp: ts, cwd,
+  message: { usage: usage(out), content: blocks },
+});
+const user = (sid, ts, cwd, text) => ({
+  type: 'user', sessionId: sid, uuid: U(), promptId: `p${uid}`, timestamp: ts, cwd,
+  message: { content: text },
+});
+const tool = (name, input) => ({ type: 'tool_use', id: `t${++uid}`, name, input });
+
+// One .jsonl per session, the way Claude Code actually lays them out.
+const bySession = new Map();
+const emit = (o) => {
+  const k = o.sessionId;
+  if (!bySession.has(k)) bySession.set(k, []);
+  bySession.get(k).push(JSON.stringify(o));
+};
+
+// Sessions that build things, spread across the invented repos.
+const plan = [
+  { repo: 'acme-api', sessions: 9, daysBack: [2, 3, 5, 6, 9, 12, 16, 20, 24], edits: 5, writes: 2 },
+  { repo: 'acme-web', sessions: 5, daysBack: [4, 7, 11, 18, 22], edits: 3, writes: 1 },
+  { repo: 'billing-service', sessions: 3, daysBack: [8, 15, 26], edits: 2, writes: 1 },
+  { repo: 'infra-terraform', sessions: 2, daysBack: [13, 19], edits: 2, writes: 0 },
+];
+let sid = 0;
+for (const p of plan) {
+  const dir = path.join(HOME, 'code', p.repo);
+  const files = REPOS[p.repo];
+  for (let i = 0; i < p.sessions; i++) {
+    const S = `s-${p.repo}-${++sid}`;
+    const ts = day(p.daysBack[i % p.daysBack.length]);
+    emit(user(S, ts, dir, 'add the thing'));
+    for (let e = 0; e < p.edits; e++) {
+      const f = path.join(dir, files[e % files.length]);
+      emit(asst(S, ts, dir, [tool('Read', { file_path: f })], 120));
+      emit(asst(S, ts, dir, [tool('Edit', { file_path: f, old_string: 'x\n'.repeat(9), new_string: 'y\n'.repeat(14) })], 400));
+    }
+    for (let w = 0; w < p.writes; w++) {
+      const f = path.join(dir, files[(w + 1) % files.length]);
+      emit(asst(S, ts, dir, [tool('Write', { file_path: f, content: 'z\n'.repeat(70) })], 700));
+    }
+    emit(asst(S, ts, dir, [tool('Bash', { command: 'npm test' })], 200));
+    if (i % 3 === 0) {
+      emit(user(S, ts, dir, 'open the PR'));
+      emit(asst(S, ts, dir, [tool('Bash', { command: 'gh pr create --fill' })], 150));
+    }
+  }
+}
+
+// Work in a plain directory — no repo.
+for (let i = 0; i < 4; i++) {
+  const S = `s-notes-${i}`;
+  const ts = day([6, 10, 17, 23][i]);
+  const dir = path.join(HOME, 'notes');
+  emit(user(S, ts, dir, 'draft the migration plan'));
+  emit(asst(S, ts, dir, [tool('Write', { file_path: path.join(dir, NOTES[i % 2]), content: 'n\n'.repeat(55) })], 900));
+}
+
+// Research: no files touched, not in a repo. The row that surprises people.
+for (let i = 0; i < 17; i++) {
+  const S = `s-res-${i}`;
+  const ts = day([1, 2, 3, 5, 7, 8, 9, 11, 12, 14, 16, 18, 20, 21, 25, 27, 28][i]);
+  emit(user(S, ts, HOME, 'what changed in the pricing API?'));
+  for (let k = 0; k < 6; k++) {
+    emit(asst(S, ts, HOME, [tool('WebFetch', { url: 'https://example.com/docs' })], 350));
+    emit(asst(S, ts, HOME, [tool('WebSearch', { query: 'pricing api changelog' })], 250));
+  }
+  emit(user(S, ts, HOME, 'and the rate limits?'));
+  emit(asst(S, ts, HOME, [tool('WebFetch', { url: 'https://example.com/limits' })], 400));
+}
+
+for (const [k, ls] of bySession) fs.writeFileSync(path.join(PROJ, `${k}.jsonl`), ls.join('\n') + '\n');
+
+// --- commits carrying that work ---------------------------------------------
+const COMMITS = {
+  'acme-api': [
+    ['src/routes/orders.ts', 'orders: handle partial refunds', 2],
+    ['src/lib/auth.ts', 'auth: rotate signing keys', 5],
+    ['src/db/schema.sql', 'schema: add refund_reason', 9],
+    ['tests/orders.test.ts', 'tests: cover partial refunds', 16],
+  ],
+  'acme-web': [
+    ['app/checkout/page.tsx', 'checkout: inline tax breakdown', 4],
+    ['app/cart/state.ts', 'cart: fix stale totals', 11],
+  ],
+  'billing-service': [['internal/invoice/render.go', 'invoice: round to minor units', 8]],
+  'infra-terraform': [['envs/prod/main.tf', 'prod: bump rds instance class', 13]],
+};
+// Date each commit to the day the session that produced it ran, so the
+// "N of your M active days ended in a commit" line reflects a real rhythm
+// rather than a fixture written all at once.
+for (const [repo, cs] of Object.entries(COMMITS)) {
+  const dir = path.join(HOME, 'code', repo);
+  for (const [f, msg, back] of cs) {
+    fs.appendFileSync(path.join(dir, f), 'changed\n');
+    const when = day(back);
+    execFileSync('git', ['-C', dir, 'add', '-A'], { stdio: 'ignore' });
+    execFileSync('git', ['-C', dir, 'commit', '-qm', msg], {
+      stdio: 'ignore',
+      env: { ...process.env, GIT_AUTHOR_DATE: when, GIT_COMMITTER_DATE: when },
+    });
+  }
+}
+console.log(HOME);