A 12-Day Codex Run to Build an Excel Clone

Matthew Berman describes giving Codex a brief goal and manually stopping it after more than 12 days, then demonstrates the resulting spreadsheet.

MBMatthew BermanPonente · Forward Future
Canal
Matthew Berman
Publicado
24 jun 2026
Vídeo
0:52
Lectura
1 min
Diapositivas
3
Original
inglés
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RESUMEN

En 30 segundos

Matthew Berman says he asked Codex to clone Excel with full feature parity and let it run for more than 12 days before stopping it. He demonstrates a spreadsheet interface, a simple formula and sorting; the short video does not establish complete Excel compatibility.

  1. 1A long-running goalBerman says the Codex task ran for more than 12 days before he stopped it manually.
  2. 2Inspecting ExcelHe says Codex opened the desktop application and examined its features while building a clone.
  3. 3Spreadsheet demonstrationBerman demonstrates cell editing and a simple formula, and says columns can be adjusted and highlighted.
  4. 4SortingHe selects ascending order to demonstrate sorting, then asks how long the task might otherwise have continued.

Conclusiones

  1. Berman says a brief Excel-cloning goal ran for more than 12 days before he manually stopped it.
  2. He says Codex inspected features in the Excel desktop app while building its version.
  3. The demonstration shows a simple arithmetic formula and an ascending sort, but does not establish full feature parity.
TEXTO COMPLETO

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01

The prompt and the run

Berman gives Codex a goal of cloning Excel with full feature parity. He says the run continued for more than 12 days before he stopped it.

The Excel-cloning goal
DIAPOSITIVA 1 / 3The Excel-cloning goalThe on-screen prompt asks Codex to clone Excel with full feature parity.

I gave Codex a short goal: `/goal Clone excel, full feature parity`. It ran for more than 12 days before I manually stopped it. I was impressed by the result.

Codex opened Excel on my computer, looked at features in the real desktop app and built its own version, I say. The resulting spreadsheet looks like Excel to me.

02

The resulting spreadsheet

He shows the interface and demonstrates a simple formula and sorting. His broad claims about completeness go beyond the examples shown.

A simple formula in the spreadsheet
DIAPOSITIVA 2 / 3A simple formula in the spreadsheetThe demonstration displays the result of adding one and two.

I demonstrate adjustable columns and cell selection, then enter `=1+2` and show the result, 3. I describe the formulas and formatting as working and call the result feature-complete. The brief demonstration shows only a few examples, so it does not establish that all formulas and formatting work or that the clone matches every Excel feature.

Sorting options
DIAPOSITIVA 3 / 3Sorting optionsThe spreadsheet shows an ascending-sort option in its menu.

I select the sort button and choose ascending order, showing the values sorted. After stopping the run myself, I wonder how long it would have continued otherwise.

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