[dolfim-ibm]

Summary

While openpyxl loads a worksheet, it creates one MergedCell object for each covered cell of a merged range, and one cell with its own Hyperlink copy for each cell of a hyperlink range. A hyperlink also sets its target as the value of each empty cell, so these cells become table data. One short element such as <mergeCell ref="A1:XFD1048576"/> or <hyperlink ref="A1:J100000"/> makes openpyxl and the table detection do work for millions of cells.

Changes

• Load workbooks through openpyxl's ExcelReader, with per-workbook budgets of 100,000 merged cells and 10,000 hyperlink cells.
• Ranges within the budget load unchanged. A range that does not fit is clipped to the cells with values in its worksheet, and to its top-left cell if it still does not fit. A warning is logged.
• The hooks (_clean_merge_range, iter_rows, iter_cols) are set on the worksheet instances of this load only and removed afterwards. No openpyxl class or module attribute changes.

Review note

The hooks rely on openpyxl 3.1.x internals (ExcelReader.read_worksheets, Workbook.create_sheet, Worksheet._clean_merge_range). The tests with a whole-sheet merged range and a large hyperlink range measure the memory, so they fail if a future openpyxl version stops calling these hooks.

Tests

• A whole-sheet merged range converts with bounded memory and keeps the merged content.
• A merged range partly beyond the data is clipped; normal merged cells keep their spans.
• A large hyperlink range converts with bounded memory and keeps the link on its top-left cell; small hyperlink ranges are unchanged.
• The existing XLSX ground-truth tests are unchanged.

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Checked commit 9f4f486398. The analysis read the diff only. It did not run code from this pull request.

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Topic labels added: bug, xlsx.

CI safety: not assessed.

Possibly related pull requests

PR	State	Signal	Assessment
#4977	open	changes the same code	not assessed

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[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 14 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
docling/backend/msexcel_backend.py	85.71%	9 Missing and 5 partials ⚠️

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