commit db1a5c21dbfdf524d3790b667d0e08cb38b9e6a4
parent d4c4c11ae42e56bab40e1b3b6ea79fb9486942a5
Author: Erik Loualiche <eloualic@umn.edu>
Date: Fri, 13 Mar 2026 19:23:51 -0500
docs: add README with usage examples for xlcat and xlset
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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+# llm-excel
+
+Command-line tools for viewing and editing Excel files, designed for use with LLMs and Claude Code.
+
+Two binaries, no runtime dependencies:
+
+- **`xlcat`** — view xlsx/xls files as markdown tables or CSV
+- **`xlset`** — modify cells in existing xlsx files, preserving formatting
+
+## Install
+
+```bash
+cargo build --release
+cp target/release/xlcat target/release/xlset ~/.local/bin/
+```
+
+Requires Rust 1.85+.
+
+## xlcat — View Excel Files
+
+```bash
+# Overview: metadata, schema, first/last 25 rows
+xlcat report.xlsx
+
+# Column names and types only
+xlcat report.xlsx --schema
+
+# Summary statistics (count, mean, std, min, max, median)
+xlcat report.xlsx --describe
+
+# Pick a sheet in a multi-sheet workbook
+xlcat report.xlsx --sheet Revenue
+
+# First 10 rows
+xlcat report.xlsx --head 10
+
+# Last 5 rows
+xlcat report.xlsx --tail 5
+
+# Both
+xlcat report.xlsx --head 10 --tail 5
+
+# All rows (overrides large-file gate)
+xlcat report.xlsx --all
+
+# CSV output for piping
+xlcat report.xlsx --csv
+xlcat report.xlsx --csv --head 100 > subset.csv
+```
+
+### Example output
+
+```
+# File: sales.xlsx (245 KB)
+# Sheets: 1
+
+## Sheet: Q1 (1240 rows x 4 cols)
+
+| Column | Type |
+|---------|--------|
+| date | Date |
+| region | String |
+| amount | Float |
+| units | Int |
+
+| date | region | amount | units |
+|---|---|---|---|
+| 2024-01-01 | East | 1234.56 | 100 |
+| 2024-01-02 | West | 987.00 | 75 |
+...
+... (1190 rows omitted) ...
+| 2024-12-30 | East | 1100.00 | 92 |
+| 2024-12-31 | West | 1250.75 | 110 |
+```
+
+### Adaptive defaults
+
+- **Single sheet, <=50 rows:** shows all data
+- **Single sheet, >50 rows:** first 25 + last 25 rows
+- **Multiple sheets:** lists schemas, pick one with `--sheet`
+- **Large file (>1MB):** schema + first 25 rows (override with `--max-size 5M`)
+
+## xlset — Edit Excel Cells
+
+```bash
+# Set a single cell
+xlset report.xlsx A2=42
+
+# Set multiple cells
+xlset report.xlsx A2=42 B2="hello world" C2=true
+
+# Preserve leading zeros with type tag
+xlset report.xlsx A2:str=07401
+
+# Target a specific sheet
+xlset report.xlsx --sheet Revenue A2=42
+
+# Write to a new file (don't modify original)
+xlset report.xlsx --output modified.xlsx A2=42
+
+# Bulk update from CSV
+xlset report.xlsx --from updates.csv
+
+# Bulk from stdin
+echo "A1,42" | xlset report.xlsx --from -
+```
+
+### Type inference
+
+Values are auto-detected: `42` becomes a number, `true` becomes boolean, `2024-01-15` becomes a date. Override with tags when needed:
+
+| Tag | Effect |
+|-----|--------|
+| `:str` | Force string (`A1:str=07401` preserves leading zero) |
+| `:num` | Force number |
+| `:bool` | Force boolean |
+| `:date` | Force date |
+
+### CSV format for `--from`
+
+```csv
+cell,value
+A1,42
+B2,hello world
+C3:str,07401
+D4,"value with, comma"
+```
+
+### What gets preserved
+
+xlset modifies only the cells you specify. Everything else is untouched: formatting, formulas, charts, conditional formatting, data validation, merged cells, images.
+
+## Claude Code integration
+
+Both tools include Claude Code skills (`/xls` and `/xlset`) for seamless use in conversations. Claude can view spreadsheets, analyze data, and make targeted edits.
+
+## Exit codes
+
+| Code | xlcat | xlset |
+|------|-------|-------|
+| 0 | Success | Success |
+| 1 | Runtime error | Runtime error |
+| 2 | Invalid arguments | Invalid arguments |
+
+## Tech
+
+- **xlcat:** calamine (Excel reading) + polars (DataFrames, statistics) + clap
+- **xlset:** umya-spreadsheet (round-trip Excel editing) + clap
+- Both compile to single static binaries with no runtime dependencies
