excel-automation

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

AGENTS.md

Audit 0.4.1 · source sha 8e06d16644df · 31 Oct 2026Report an issue or request a re-scan

• Publisherdaymade GitHub userOwner of the repository this skill is read from
• Source folderdaymade/claude-code-skills/daymade-docs/excel-automationThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdict8e06d16644dfA new audit runs when the source changes
• Repository statusNot archivedPushed today
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Creates formatted Excel reports with openpyxl, parses complex xlsm financial models with stdlib zipfile+xml when openpyxl fails, and controls Excel windows on macOS via AppleScript. Reconstructs images or scans of paper…

---
name: excel-automation
disable-model-invocation: true
description: >-
  Creates formatted Excel reports with openpyxl, parses complex xlsm financial
  models with stdlib zipfile+xml when openpyxl fails, and controls Excel windows
  on macOS via AppleScript. Reconstructs images or scans of paper forms as
  editable XLSX files with printable layouts.
---

# Excel Automation

Create professional Excel files, parse complex financial models, and control Excel on macOS.

For an image or scan of a paper form that needs editable cells and a printable
layout, load [Printable forms](references/printable-forms.md) before creating the
workbook. Follow the host's designated spreadsheet authoring tool; use the
openpyxl examples below only when that tool is permitted.

## Quick Start

Before a command brings Excel forward or changes its visible window, check user
activity and other agents' occupancy. Use only foreground operations covered by
the current task's authorization. If the surface is in use, occupancy is unknown,
or unexpected input occurs, stop input and continue independent background work.

```bash
# Create a formatted Excel report
uv run --with openpyxl scripts/create_formatted_excel.py output.xlsx

# Parse a complex xlsm that openpyxl can't handle
uv run scripts/parse_complex_excel.py model.xlsm              # List sheets
uv run scripts/parse_complex_excel.py model.xlsm "DCF"        # Extract a sheet
uv run scripts/parse_complex_excel.py model.xlsm --fix        # Fix corrupted names

# Control Excel via AppleScript (with timeout to prevent hangs)
timeout 5 osascript -e 'tell application "Microsoft Excel" to activate'
```

## Overview

| Capability | Tool | When to Use |
|-----------|------|-------------|
| **Create** formatted Excel | `openpyxl` | Reports, mockups, dashboards |
| **Parse** complex xlsm/xlsx | `zipfile` + `xml.etree` | Financial models, VBA workbooks, >1MB files |
| **Control** Excel window | AppleScript (`osascript`) | Zoom, scroll, select cells programmatically |

## Tool Selection Decision Tree

```
Is the file simple (data export, no VBA, <1MB)?
├─ YES → openpyxl or pandas
└─ NO
   ├─ Is it .xlsm or from investment bank / >1MB?
   │   └─ YES → zipfile + xml.etree.ElementTree (stdlib)
   └─ Is it truly .xls (BIFF format)?
       └─ YES → xlrd
```

**Signals of "complex" Excel**: file >1MB, `.xlsm` extension, from investment bank/broker, contains VBA macros.

**IMPORTANT**: Always run `file <path>` first — extensions lie. A `.xls` file may actually be a ZIP-based xlsx.

## Creating Excel Files (openpyxl)

### Professional Color Convention (Investment Banking Standard)

Apply these colors to financial reports using that convention. For a paper form,
preserve its intended print appearance; do not add input colors by default.

| Color | RGB Code | Meaning |
|-------|----------|---------|
| Blue | `0000FF` | User input / assumption |
| Black | `000000` | Calculated value |
| Green | `008000` | Cross-sheet reference |
| White on dark blue | `FFFFFF` on `4472C4` | Section headers |
| Dark blue text | `1F4E79` | Title |

### Core Formatting Patterns

```python
from openpyxl.styles import Font, PatternFill, Border, Side, Alignment

# Fonts
BLUE_FONT = Font(color="0000FF", size=10, name="Calibri")
BLACK_FONT_BOLD = Font(color="000000", size=10, name="Calibri", bold=True)
GREEN_FONT = Font(color="008000", size=10, name="Calibri")
HEADER_FONT = Font(color="FFFFFF", size=12, name="Calibri", bold=True)

# Fills
DARK_BLUE_FILL = PatternFill("solid", fgColor="4472C4")
LIGHT_BLUE_FILL = PatternFill("solid", fgColor="D9E1F2")
INPUT_GREEN_FILL = PatternFill("solid", fgColor="E2EFDA")
LIGHT_GRAY_FILL = PatternFill("solid", fgColor="F2F2F2")

# Borders
THIN_BORDER = Border(bottom=Side(style="thin", color="B2B2B2"))
BOTTOM_DOUBLE = Border(bottom=Side(style="double", color="000000"))
```

### Number Format Codes

| Format | Code | Example |
|--------|------|---------|
| Currency | `'$#,##0'` | $1,234 |
| Currency with decimals | `'$#,##0.00'` | $1,234.56 |
| Percentage | `'0.0%'` | 12.3% |
| Percentage (2 decimal) | `'0.00%'` | 12.34% |
| Number with commas | `'#,##0'` | 1,234 |
| Multiplier | `'0.0x'` | 1.5x |

### Conditional Formatting (Sensitivity Tables)

Red-to-green gradient for sensitivity analysis:

```python
from openpyxl.formatting.rule import ColorScaleRule

rule = ColorScaleRule(
    start_type="min", start_color="F8696B",   # Red (low)
    mid_type="percentile", mid_value=50, mid_color="FFEB84",  # Yellow (mid)
    end_type="max", end_color="63BE7B"         # Green (high)
)
ws.conditional_formatting.add(f"B2:F6", rule)
```

### Execution

```bash
uv run --with openpyxl scripts/create_formatted_excel.py
```

Full template script: See `scripts/create_formatted_excel.py`

## Parsing Complex Excel (zipfile + xml)

When openpyxl fails on complex xlsm files (corrupted DefinedNames, complex VBA), use stdlib directly.

### XLSX Internal ZIP Structure

```
file.xlsx (ZIP archive)
├── [Content_Types].xml
├── xl/
│   ├── workbook.xml          ← Sheet names + order
│   ├── sharedStrings.xml     ← All text values (lookup table)
│   ├── worksheets/
│   │   ├── sheet1.xml        ← Cell data for sheet 1
│   │   ├── sheet2.xml        ← Cell data for sheet 2
│   │   └── ...
│   └── _rels/
│       └── workbook.xml.rels ← Maps rId → sheetN.xml
└── _rels/.rels
```

### Sheet Name Resolution

Sheet names in `workbook.xml` link to physical files via `_rels/workbook.xml.rels`:

```python
import zipfile
import xml.etree.ElementTree as ET

MAIN_NS = 'http://schemas.openxmlformats.org/spreadsheetml/2006/main'
REL_NS = 'http://schemas.openxmlformats.org/officeDocument/2006/relationships'
RELS_NS = 'http://schemas.openxmlformats.org/package/2006/relationships'

def get_sheet_path(zf, sheet_name):
    """Resolve sheet name to physical XML file path inside ZIP."""
    # Step 1: workbook.xml → find rId for the sheet name
    wb_xml = ET.fromstring(zf.read('xl/workbook.xml'))
    sheets = wb_xml.findall(f'.

Excerpt, first 6,000 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

uv run --with openpyxl scripts/create_formatted_excel.py output.xlsx
uv run scripts/parse_complex_excel.py model.xlsm              # List sheets
uv run scripts/parse_complex_excel.py model.xlsm "DCF"        # Extract a sheet
uv run scripts/parse_complex_excel.py model.xlsm --fix        # Fix corrupted names
uv run --with openpyxl scripts/create_formatted_excel.py

git clone https://github.com/daymade/claude-code-skills
git -C claude-code-skills checkout 8e06d16644df

Works in

1. 2026-10-31
   ✓SAFE B 89 / 100

   first audit · source 8e06d16644df

Questions about excel-automation

• github.com/daymade/claude-code-skills/tree/main/daymade-docs/exc — the audited source at commit 8e06d16644df and every finding aboveObserved · 31 Oct 2026

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