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Agent skill

Openpyxl Merged Cell Safe Write

by HKUDS in HKUDS/OpenSpace

Safe pattern for writing values to merged cells in openpyxl spreadsheets

MITAuto-check passedDocuments & Office

Install Openpyxl Merged Cell Safe Write

skills CLI
$ npx skills add HKUDS/OpenSpace --skill openpyxl-merged-cell-safe-write -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install HKUDS/OpenSpace openpyxl-merged-cell-safe-write --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/HKUDS/OpenSpace.git skills-src && mkdir -p .claude/skills && cp -r skills-src/benchmarks/gdpval/skills/openpyxl-merged-cell-safe-write .claude/skills/openpyxl-merged-cell-safe-write && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
openpyxl-merged-cell-safe-write
GitHub stars
7.8k
Token cost
~852 tokens
SKILL.md length
204 words
Files
2
Skills in repo
199
Repo updated
First seen
Licence
MIT

At a glance

Safe pattern for writing values to merged cells in openpyxl spreadsheets

  • Works in 5 steps: Identify merge ranges you need for… → Write values to the top-left cell of… → Apply the merge using ws.merge_cells() → …
  • Tasks that involve Excel spreadsheets
  • SKILL.md covers Problem, Core Rule, Correct Pattern and Incorrect Pattern (Causes…, plus 5 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Openpyxl Merged Cell Safe Write is an agent skill from HKUDS/OpenSpace. Safe pattern for writing values to merged cells in openpyxl spreadsheets

Its SKILL.md is about 850 tokens, which your agent loads only when the skill is triggered. The skill folder holds 1 other file.

It sits in Documents & Office, covering Excel spreadsheets. It works with openpyxl. The repository describes itself as: "OpenSpace: The Skill Management Layer for AI Agents" -- https://open-space.cloud/. The licence is MIT.

When your agent uses it

  • Tasks that involve Excel spreadsheets

Example prompts

  • “/openpyxl-merged-cell-safe-write”

Requirements

  • Python 3

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

  1. Identify merge ranges you need for headers, titles, or grouped data
  2. Write values to the top-left cell of each range before merging
  3. Apply the merge using ws.merge_cells()
  4. Apply formatting (font, alignment, borders) to the top-left cell
  5. Verify by checking that only the top-left cell holds the value

What it can do on your machine

Read from SKILL.md and the folder at commit 3827781. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are python).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Openpyxl Merged Cell Safe Write loads about 852 tokens when it runs. Until then it costs about 26 tokens; SKILL.md has 204 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~26
When it runs · the whole SKILL.md, loaded when a task matches
~852

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from HKUDS/OpenSpace at commit 3827781, republished under its MIT licence (© HKUDS). 204 words, ~852 tokens.

Download SKILL.mdSave it as .claude/skills/openpyxl-merged-cell-safe-write/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
openpyxl-merged-cell-safe-write
description
Safe pattern for writing values to merged cells in openpyxl spreadsheets

OpenPyXL Merged Cell Safe Write Pattern

Problem

When creating formatted spreadsheets with openpyxl, merging cells and then assigning values to them causes MergedCell errors. This is a common pitfall that can consume multiple failed iterations.

Core Rule

Always assign values to the top-left cell of a merge range BEFORE applying the merge, or avoid assigning to merged cells entirely after the merge is applied.

Correct Pattern

python
from openpyxl import Workbook

wb = Workbook()
ws = wb.active

# CORRECT: Set value first, then merge
ws['A1'] = 'Quarterly Revenue Report'  # Assign to top-left cell first
ws.merge_cells('A1:D1')                # Then apply merge

# Also set formatting after merge
ws['A1'].font = Font(bold=True, size=16)
ws['A1'].alignment = Alignment(horizontal='center')

Incorrect Pattern (Causes MergedCell Error)

python
# WRONG: Merge first, then assign value
ws.merge_cells('A1:D1')
ws['A1'] = 'Quarterly Revenue Report'  # This raises MergedCell error!

Step-by-Step Procedure

  1. Identify merge ranges you need for headers, titles, or grouped data
  2. Write values to the top-left cell of each range before merging
  3. Apply the merge using ws.merge_cells()
  4. Apply formatting (font, alignment, borders) to the top-left cell
  5. Verify by checking that only the top-left cell holds the value

Additional Guidelines

For Multiple Merged Regions
python
# Define all merges with their values
merges = [
    ('A1', 'D1', 'Quarterly Revenue Report'),
    ('A3', 'B3', 'Product'),
    ('C3', 'D3', 'Sales Data'),
]

for start_col, end_col, value in merges:
    cell_ref = f'{start_col}'  # Top-left cell
    ws[cell_ref] = value       # Set value first
    ws.merge_cells(f'{start_col}:{end_col}')  # Then merge
When Modifying Existing Merged Cells

If you need to update a value in an already-merged range:

python
# Get the top-left cell of the merged range
top_left = 'A1'  # Know your merge structure
ws[top_left] = 'New Value'  # Only modify the top-left cell
Checking for Merged Cells
python
# Check if a cell is within a merged range
def is_cell_merged(ws, cell_ref):
    for merged_range in ws.merged_cells.ranges:
        if cell_ref in merged_range:
            return True
    return False

# Or check before writing
if not is_cell_merged(ws, 'A1'):
    ws['A1'] = 'Value'
    ws.merge_cells('A1:D1')

Common Use Cases

Use CasePattern
Title headersWrite to A1, then merge A1:D1
Section headersWrite to first cell, then merge across columns
Grouped labelsWrite to top-left, merge the group range
Centered contentWrite, merge, then apply center alignment

Quick Reference

python
# ✅ DO: Value → Merge → Format
ws['A1'] = 'Title'
ws.merge_cells('A1:E1')
ws['A1'].alignment = Alignment(horizontal='center')

# ❌ DON'T: Merge → Value
ws.merge_cells('A1:E1')
ws['A1'] = 'Title'  # Error!

Testing Your Spreadsheet

After creation, verify merged cells work correctly:

python
# Save and reload to confirm no errors
wb.save('test.xlsx')

# Reload and check
wb2 = load_workbook('test.xlsx')
ws2 = wb2.active
print(ws2['A1'].value)  # Should show the title value

© HKUDS, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file in benchmarks/gdpval/skills/openpyxl-merged-cell-safe-write of HKUDS/OpenSpace.

  • SKILL.md
  • .skill_id

Open the folder on GitHubat commit 3827781

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Openpyxl Merged Cell Safe Write compared with similar skills
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Works with

Categories

Questions about Openpyxl Merged Cell Safe Write

What does Openpyxl Merged Cell Safe Write do?

Safe pattern for writing values to merged cells in openpyxl spreadsheets. Openpyxl Merged Cell Safe Write is an agent skill from HKUDS/OpenSpace.

When should I use Openpyxl Merged Cell Safe Write?

Openpyxl Merged Cell Safe Write fits situations like: tasks that involve Excel spreadsheets.

How do I install Openpyxl Merged Cell Safe Write in Claude Code?

Run `npx skills add HKUDS/OpenSpace --skill openpyxl-merged-cell-safe-write -a claude-code`. Or copy the skill folder (benchmarks/gdpval/skills/openpyxl-merged-cell-safe-write in HKUDS/OpenSpace) into .claude/skills/openpyxl-merged-cell-safe-write in your project. Claude Code loads it when a task matches its description.

How do I install Openpyxl Merged Cell Safe Write in Codex?

Run `npx skills add HKUDS/OpenSpace --skill openpyxl-merged-cell-safe-write -a codex`. Or copy the skill folder (benchmarks/gdpval/skills/openpyxl-merged-cell-safe-write in HKUDS/OpenSpace) into .agents/skills/openpyxl-merged-cell-safe-write in your project. Codex loads it when a task matches its description.

Can I use Openpyxl Merged Cell Safe Write in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add HKUDS/OpenSpace --skill openpyxl-merged-cell-safe-write -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/openpyxl-merged-cell-safe-write, .gemini/skills/openpyxl-merged-cell-safe-write, .github/skills/openpyxl-merged-cell-safe-write and .opencode/skills/openpyxl-merged-cell-safe-write in your project.

What does Openpyxl Merged Cell Safe Write need to run?

SKILL.md names no scripts, command-line tools or credentials: Openpyxl Merged Cell Safe Write is instructions for the agent only. Our summary lists: Python 3.

Does Openpyxl Merged Cell Safe Write access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Openpyxl Merged Cell Safe Write safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Openpyxl Merged Cell Safe Write use?

Openpyxl Merged Cell Safe Write is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Openpyxl Merged Cell Safe Write use?

About 852 tokens (SKILL.md is roughly 3.4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Openpyxl Merged Cell Safe Write?

Skills that share tags, products or a category with Openpyxl Merged Cell Safe Write: XLSX (NousResearch/hermes-agent, 253k stars), Z Md Excel (tjxj/z-skills, 548 stars), Sn Da Large File Analysis (MichaelYang-lyx/AIDABench, 111 stars) and XLSX (prapaa-ai/agav, 168 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Openpyxl Merged Cell Safe Write?

HKUDS (a GitHub organization) maintains it in HKUDS/OpenSpace, which has 7,754 GitHub stars. The repository holds 199 skills in this directory. The repository was last updated on August 12, 2026.

Source: HKUDS/OpenSpace on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.