tools-only XLSX Skill Analysis
Comprehensive analysis of the Excel spreadsheet generation skill.
Overview
The XLSX skill handles Excel spreadsheet generation through a validation-centric workflow. Unlike the DOCX skill which uses multiple tools and languages, XLSX relies primarily on Python plus openpyxl for creation, with a 77MB binary called KimiXlsx handling validation, PivotTable creation, and formula checking.
Technology Stack
Creation uses Python plus openpyxl plus pandas for spreadsheet structure, data, formulas, and styling.
Validation uses the KimiXlsx CLI, a 77MB binary, for formula checking, schema validation, and PivotTables.
The KimiXlsx Binary
At 77,001,601 bytes, KimiXlsx is the largest binary in the Kimi system.
Binary Details
$ file KimiXlsx
KimiXlsx: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV),
dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2,
for GNU/Linux 2.6.32, BuildID[sha1]=771f85eb041bea21c911f46511d0b9727b0b6f68,
stripped
The binary is an ELF 64-bit LSB PIE executable for x86-64 architecture. It is 77 MB and stripped. PIE is enabled.
Size breakdown:
- OpenXML SDK: ~30 MB
- PivotTable Engine: ~20 MB
- Chart Engine: ~15 MB
- Validation Logic: ~10 MB
- Runtime: ~2 MB
Commands
recheck detects formula errors like #VALUE! and #DIV/0!. Exit code 0 means pass. Exit code 1 means fail.
reference-check validates formula references for out-of-range or header inclusion errors. Exit code 0 means pass. Exit code 1 means fail.
validate checks OpenXML schema and forbidden functions. Exit code 0 means pass. Non-zero means fail.
pivot creates PivotTable with chart. Exit code varies.
chart-verify confirms charts have data. Exit code 0 means pass. Exit code 1 means fail.
inspect performs structure analysis with JSON output. Exit code 0 means pass.
Validation Workflow
Per-Sheet Validation (Zero Tolerance)
For each sheet:
1. PLAN → Design structure, formulas, references
2. CREATE → Write data, formulas, styling (ipython)
3. SAVE → wb.save()
4. CHECK → recheck + reference-check → Fix until 0 errors
5. NEXT → Proceed only when current sheet passes
After ALL sheets:
6. VALIDATE → validate command → Exit code 0 required
7. DELIVER → Only validated files
Key principle: Validation is interleaved with creation, not just post-processing. Shell commands act as circuit breakers between sheets.
Standard Workflow
Read SKILL.md (925 lines)
↓
Plan sheets (Cover, Data, Analysis, Pivot)
↓
Sheet 1 (Cover):
ipython: Create cover styling
ipython: Save
shell: recheck → 0 errors?
shell: reference-check → 0 errors?
Yes → Next sheet
↓
Sheet 2 (Data):
ipython: Add data + formulas
ipython: Add charts
ipython: Save
shell: recheck → 0?
shell: reference-check → 0?
Yes → Next sheet
↓
...
Final Validation:
shell: validate → Exit code 0?
Yes → Deliver
Formula Constraints
Forbidden Functions (Excel 365 Only)
These functions work in Excel 365 but crash in Excel 2019 and earlier:
FILTER() should be replaced with AutoFilter or SUMIF and COUNTIF.
UNIQUE() should be replaced with Remove Duplicates or COUNTIF helper.
XLOOKUP() should be replaced with INDEX plus MATCH.
XMATCH() should be replaced with MATCH.
LET() should be replaced with helper cells.
LAMBDA() should be replaced with named ranges.
SORT() and SORTBY() should be replaced with manual sorting.
The validate command specifically checks for these and rejects files that use them.
Formula Mandate
The skill requires Excel formulas, not calculated values:
# CORRECT - Formula
ws['C2'] = '=A2+B2'
# FORBIDDEN - Static value
result = value_a + value_b
ws['C2'] = result # Violates skill principles
Benefits:
- Enables user modification in Excel
- Self-updating when referenced data changes
- Professional spreadsheet standards
PivotTable Creation Protocol
PivotTables have strict workflow constraints.
Correct Order
openpyxl creates base.xlsx (all sheets except pivot)
↓
KimiXlsx pivot command (adds PivotTable)
↓
validate
↓
DELIVER (do NOT modify again!)
Wrong Order (Corrupts File)
pivot creates pivot.xlsx
↓
openpyxl opens to add Cover sheet ← CORRUPTS pivotCache!
↓
File broken
Critical rule: The pivot binary modifies Excel files in ways openpyxl does not understand, corrupting the pivotCache if subsequently opened.
Pivot Command
/app/.kimi/skills/xlsx/scripts/KimiXlsx pivot \
data.xlsx output.xlsx \
--source "Sales!A1:F100" \
--rows "Category" \
--values "Revenue:sum" \
--location "Summary!A3" \
--chart "bar"
IPython Usage Patterns
Workbook Construction
from openpyxl import Workbook
from openpyxl.styles import PatternFill, Font, Border, Alignment
from openpyxl.chart import BarChart, Reference
from openpyxl.formatting.rule import DataBarRule
# Create
wb = Workbook()
ws = wb.active
ws.title = "Data"
# Data with formulas
ws['C2'] = '=A2+B2' # Sum
ws['D2'] = '=C2/B2*100' # Percentage
ws['E2'] = '=SUM(A2:A100)' # Aggregation
# Styling
ws['A1'].font = Font(bold=True, color="FFFFFF")
ws['A1'].fill = PatternFill(start_color="333333", fill_type="solid")
# Conditional formatting
ws.conditional_formatting.add('C2:C100',
DataBarRule(start_type='min', end_type='max', color='4A90D9'))
# Charts
chart = BarChart()
chart.add_data(Reference(ws, min_col=2, min_row=1, max_row=4))
ws.add_chart(chart, "E2")
wb.save('/mnt/okcomputer/output/data.xlsx')
Cover Page Creation
# Cover sheet (always first)
cover = wb.create_sheet("Cover", 0)
cover.sheet_view.showGridLines = False
# Merged title
cover.merge_cells('B2:G2')
cover['B2'] = "Report Title"
cover['B2'].font = Font(size=20, bold=True)
# Metrics table with cross-sheet references
cover['B5'] = "Key Metrics"
cover['B6'] = "Total Revenue"
cover['C6'] = '=Data!E100' # Formula linking to data sheet
Cross-Sheet References
# VLOOKUP pattern
ws['D2'] = '=IFERROR(VLOOKUP(A2,Data!$G$2:$I$50,3,FALSE),"N/A")'
# Cross-sheet formula
summary['B2'] = '=SUM(Data!C2:C100)'
Visual Design System
Minimalist Monochrome (Default)
Base colors: White (#FFFFFF), Black (#000000), Grey shades
Accent: Blue only (#0066CC, #4A90D9, #E6F0FA)
Forbidden: All other colors
Professional Finance
Background: #ECF0F1 (light gray)
Header: #1F4E79 (dark blue)
Regional convention: China uses Red for Up and Green for Down. International uses Green for Up and Red for Down.
Key Insights
1. Validation-First Design
Unlike DOCX where validation is a final step, XLSX enforces per-sheet validation. Shell commands are invoked multiple times during creation.
2. Binary as "Secret Sauce"
The 77MB KimiXlsx binary parses Excel OpenXML natively. It detects formula errors openpyxl cannot catch. It validates Excel 365 versus 2019 compatibility. It creates PivotTables via pure OpenXML SDK.
3. Formula-Centric Philosophy
Formulas over values enable user modification. They are self-updating when data changes. They follow professional spreadsheet standards.
4. Python-Only Creation (Except Pivot)
Unlike DOCX which uses C# generation, XLSX uses Python and openpyxl for everything except PivotTable creation. This is because openpyxl handles styling and formulas well. There is no compilation step for faster iteration. PivotTable cache is too complex for openpyxl.
5. Validation-as-Gatekeeper
The agent has freedom to write any Python and openpyxl code. The binary validator enforces correctness. Per-sheet validation prevents error accumulation. Formula errors are blocking, not warnings.
Security Assessment
Network access: None. The binary operates offline for validation.
File system: Read-only for input, write for output.
Execution: Sandboxed.
Stripped: Yes, making it harder to reverse engineer.
The binary is completely offline. There are no package downloads or external service contacts.