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The Liberation Engine

Things to make / Recipe 10 of 14 · Organize

Turn a receipt stack into a budget

See each purchase and check every total against its source.

What the agent made

Ran it for real with Claude Code 2.1.292 and OMP 18.8.5 on 2026-10-08, in an empty session with no saved memory. Your result will differ.

SAVED OUTPUT · spending.csv
datestoreitemamountcategorysource_filename
2025-05-05Pebble PantryOats4.50Groceriesreceipt-01.txt
2025-05-05Pebble PantryDried berries3.25Groceriesreceipt-01.txt
2025-05-05Pebble PantryLemon2.25Groceriesreceipt-01.txt
2025-05-06Lantern StationeryNotebook6.40Office Suppliesreceipt-02.txt
2025-05-06Lantern StationeryPencil1.60Office Suppliesreceipt-02.txt
2025-05-07Pebble PantryBread3.00Groceriesreceipt-03.txt
2025-05-07Pebble PantryMilk2.00Groceriesreceipt-03.txt
2025-05-07Pebble PantryApple1.50Groceriesreceipt-03.txt
2025-05-08Beacon HardwareBatteries9.00Hardwarereceipt-04.txt
2025-05-08Beacon HardwareTape4.00Hardwarereceipt-04.txt

The same prompt in OMP made its own version: open what OMP made. Two runs, two different results: that is normal.

Make your own

  1. Get the files

    Download the practice folder (ZIP)

    Unzip it: you get a folder called cli-practice with 4 fictional files. Download four fictional typed receipts in receipts/ with 10 priced lines total.

  2. Open your agent in that folder

    Open a terminal in cli-practice and type claude or omp --approval-mode always-ask. First time? Set up in about five minutes, with steps for Mac, Windows, and Linux.

  3. Paste this prompt

    Work only inside this practice folder. Read the text files in receipts/. Write spending.csv with date, store, item, amount, category, source filename: one row per priced item, including any explicitly listed tax or fee. Use two-decimal dollar amounts and no invented prices. Write totals.txt with totals by category and by receipt, a grand total, and any mismatch with printed subtotals or totals. Calculate using Python's standard library Decimal. Do not alter input files, use the network, install packages, send messages, or read outside this folder. Output must work offline.

    The prompt asks the agent to stay in this folder; it cannot enforce that. Read each file change and command before you approve it.

  4. Check it yourself

    Open cli-practice/spending.csv in a spreadsheet app or text editor, then:

    Human check: Add the three amounts on receipt-01.txt by hand, compare its receipt total in totals.txt, and match its three CSV rows.

    When we checked the recording above: Read receipt-01 and all three matching CSV rows: 4.50 + 3.25 + 2.25 = 10.00, agreeing with printed subtotal, printed total, and totals.txt; four receipt totals sum to 37.50. All input files unchanged.

Why an agent, not a chat window

An agent reads several local documents, extracts itemized rows, and writes a reconciled table you can open in a spreadsheet.