xl-extract

name	xl-extract
description	Extract Excel worksheets as CSV-formatted .txt files from workbooks or folders

Excel Extract

Extract each worksheet from Excel workbooks as a CSV-formatted .txt file, placed alongside the source file. Accepts a folder (recursive) or a single .xlsx/.xls file.

Instructions

When the user asks to extract or convert Excel spreadsheets to CSV or text, run the following command:

dotnet run "${CLAUDE_SKILL_DIR}/xl-extract.cs" <rootFolder|file.xlsx>

${CLAUDE_SKILL_DIR} resolves to this skill's directory regardless of where it's installed. Replace the argument with the absolute or relative path to a directory or a single Excel file.

Behaviour

• Folder mode: recursively finds every .xlsx and .xls file under the given directory and all subfolders.
• Single-file mode: processes the specified workbook directly.
• For each worksheet, creates a sidecar file named <workbookname>-<sheetname>.txt in the same directory as the source workbook.
• Output is RFC 4180-compliant CSV: cells containing commas, double-quotes, or newlines are wrapped in double-quotes, and embedded double-quotes are escaped as "".
• Skips any sheet whose output file already exists (idempotent — safe to re-run).
• Logs one tagged line per sheet: [OK], [SKIP], or [ERROR].
• Prints a summary at the end: total workbooks found, sheets processed, skipped, and errors.

Output Example

Scanning: /data/spreadsheets

[OK]    /data/spreadsheets/Budget.xlsx :: Q1 Sales
[OK]    /data/spreadsheets/Budget.xlsx :: Q2 Sales
[SKIP]  /data/spreadsheets/Budget.xlsx :: Summary
[ERROR] /data/spreadsheets/Locked.xlsx :: Sheet1
        InvalidOperationException: The workbook is password protected.

Done. Total: 2 | Processed: 2 | Skipped: 1 | Errors: 1

When to Use

• Bulk ingestion pipelines where spreadsheet data is needed as structured text for indexing or analysis.
• Pre-processing step before feeding tabular data to Claude.
• Any workflow requiring plaintext CSV versions of Excel sheets without manual export.

Prerequisites

• .NET 10 SDK installed and dotnet available on the PATH.
• The ClosedXML@0.102.3 NuGet package is restored automatically on first run.
• Write access to the directories containing the workbooks (for creating .txt output files).

Limitations

• .xlsm macro-enabled workbooks are opened in read-only mode; macros are not executed.
• Charts, images, and other embedded objects are ignored — only cell values are exported.
• Formula results use the cached values stored in the workbook; formulas are not recalculated.
• Password-protected workbooks will produce an [ERROR] entry and be skipped.