docx

$npx skills add anthropics/skills --skill docx
SKILL.md

Docx

A .docx file is a ZIP archive containing XML files. Task Approach

DOCX creation, editing, and analysis

Overview

A .docx file is a ZIP archive containing XML files.

Quick Reference

Task
Approach
Read/analyze content
pandoc or unpack for raw XML
Create new document
Use docx-js - see Creating New Documents below
Edit existing document
Unpack → edit XML → repack - see Editing Existing Documents below

Converting .doc to .docx

Legacy .doc files must be converted before editing:
python scripts/office/soffice.py --headless --convert-to docx document.doc

Reading Content

# Text extraction with tracked changes
pandoc --track-changes=all document.docx -o output.md

# Raw XML access
python scripts/office/unpack.py document.docx unpacked/
`### Converting to Images`
python scripts/office/soffice.py --headless --convert-to pdf document.docx
pdftoppm -jpeg -r 150 document.pdf page

Accepting Tracked Changes

To produce a clean document with all tracked changes accepted (requires LibreOffice):
python scripts/accept_changes.py input.docx output.docx

Creating New Documents

Generate .docx files with JavaScript, then validate. Install: npm install -g docx

Setup

const { Document, Packer, Paragraph, TextRun, Table, TableRow, TableCell, ImageRun,
        Header, Footer, AlignmentType, PageOrientation, LevelFormat, ExternalHyperlink,
        TableOfContents, HeadingLevel, BorderStyle, WidthType, ShadingType,
        VerticalAlign, PageNumber, PageBreak } = require('docx');

const doc = new Document({ sections: [{ children: [/* content */] }] });
Packer.toBuffer(doc).then(buffer => fs.writeFileSync("doc.docx", buffer));

Validation

After creating the file, validate it. If validation fails, unpack, fix the XML, and repack.
python scripts/office/validate.py doc.docx

Page Size

// CRITICAL: docx-js defaults to A4, not US Letter
// Always set page size explicitly for consistent results
sections: [{
  properties: {
    page: {
      size: {
        width: 12240,   // 8.5 inches in DXA
        height: 15840   // 11 inches in DXA
      },
      margin: { top: 1440, right: 1440, bottom: 1440, left: 1440 } // 1 inch margins
    }
  },
  children: [/* content */]
}]
Common page sizes (DXA units, 1440 DXA = 1 inch):
Paper
Width
Height
Content Width (1" margins)
US Letter
12,240
15,840
9,360
A4 (default)
11,906
16,838
9,026
Landscape orientation: docx-js swaps width/height internally, so pass portrait dimensions and let it handle the swap:
size: {
  width: 12240,   // Pass SHORT edge as width
  height: 15840,  // Pass LONG edge as height
  orientation: PageOrientation.LANDSCAPE  // docx-js swaps them in the XML
},
// Content width = 15840 - left margin - right margin (uses the long edge)

Styles (Override Built-in Headings)

Use Arial as the default font (universally supported). Keep titles black for readability.
const doc = new Document({
  styles: {
    default: { document: { run: { font: "Arial", size: 24 } } }, // 12pt default
    paragraphStyles: [
      // IMPORTANT: Use exact IDs to override built-in styles
      { id: "Heading1", name: "Heading 1", basedOn: "Normal", next: "Normal", quickFormat: true,
        run: { size: 32, bold: true, font: "Arial" },
        paragraph: { spacing: { before: 240, after: 240 }, outlineLevel: 0 } }, // outlineLevel required for TOC
      { id: "Heading2", name: "Heading 2", basedOn: "Normal", next: "Normal", quickFormat: true,
        run: { size: 28, bold: true, font: "Arial" },
        paragraph: { spacing: { before: 180, after: 180 }, outlineLevel: 1 } },
    ]
  },
  sections: [{
    children: [
      new Paragraph({ heading: HeadingLevel.HEADING_1, children: [new TextRun("Title")] }),
    ]
  }]
});
`### Lists (NEVER use unicode bullets)`
// ❌ WRONG - never manually insert bullet characters
new Paragraph({ children: [new TextRun("• Item")] })  // BAD
new Paragraph({ children: [new TextRun("\u2022 Item")] })  // BAD

// ✅ CORRECT - use numbering config with LevelFormat.BULLET
const doc = new Document({
  numbering: {
    config: [
      { reference: "bullets",
        levels: [{ level: 0, format: LevelFormat.BULLET, text: "•", alignment: AlignmentType.LEFT,
          style: { paragraph: { indent: { left: 720, hanging: 360 } } } }] },
      { reference: "numbers",
        levels: [{ level: 0, format: LevelFormat.DECIMAL, text: "%1.", alignment: AlignmentType.LEFT,
          style: { paragraph: { indent: { left: 720, hanging: 360 } } } }] },
    ]
  },
  sections: [{
    children: [
      new Paragraph({ numbering: { reference: "bullets", level: 0 },
        children: [new TextRun("Bullet item")] }),
      new Paragraph({ numbering: { reference: "numbers", level: 0 },
        children: [new TextRun("Numbered item")] }),
    ]
  }]
});

// ⚠️ Each reference creates INDEPENDENT numbering
// Same reference = continues (1,2,3 then 4,5,6)
// Different reference = restarts (1,2,3 then 1,2,3)

Tables

CRITICAL: Tables need dual widths - set both columnWidths on the table AND width on each cell. Without both, tables render incorrectly on some platforms.
// CRITICAL: Always set table width for consistent rendering
// CRITICAL: Use ShadingType.CLEAR (not SOLID) to prevent black backgrounds
const border = { style: BorderStyle.SINGLE, size: 1, color: "CCCCCC" };
const borders = { top: border, bottom: border, left: border, right: border };

new Table({
  width: { size: 9360, type: WidthType.DXA }, // Always use DXA (percentages break in Google Docs)
  columnWidths: [4680, 4680], // Must sum to table width (DXA: 1440 = 1 inch)
  rows: [
    new TableRow({
      children: [
        new TableCell({
          borders,
          width: { size: 4680, type: WidthType.DXA }, // Also set on each cell
          shading: { fill: "D5E8F0", type: ShadingType.CLEAR }, // CLEAR not SOLID
          margins: { top: 80, bottom: 80, left: 120, right: 120 }, // Cell padding (internal, not added to width)
          children: [new Paragraph({ children: [new TextRun("Cell")] })]
        })
      ]
    })
  ]
})
Table width calculation:
Always use WidthType.DXA — WidthType.PERCENTAGE breaks in Google Docs.
// Table width = sum of columnWidths = content width
// US Letter with 1" margins: 12240 - 2880 = 9360 DXA
width: { size: 9360, type: WidthType.DXA },
columnWidths: [7000, 2360]  // Must sum to table width
Width rules:
  • Always use WidthType.DXA — never WidthType.PERCENTAGE (incompatible with Google Docs)
  • Table width must equal the sum of columnWidths
  • Cell width must match corresponding columnWidth
  • Cell margins are internal padding - they reduce content area, not add to cell width
  • For full-width tables: use content width (page width minus left and right margins)

Images

// CRITICAL: type parameter is REQUIRED
new Paragraph({
  children: [new ImageRun({
    type: "png", // Required: png, jpg, jpeg, gif, bmp, svg
    data: fs.readFileSync("image.png"),
    transformation: { width: 200, height: 150 },
    altText: { title: "Title", description: "Desc", name: "Name" } // All three required
  })]
})
`### Page Breaks`
// CRITICAL: PageBreak must be inside a Paragraph
new Paragraph({ children: [new PageBreak()] })

// Or use pageBreakBefore
new Paragraph({ pageBreakBefore: true, children: [new TextRun("New page")] })
`### Table of Contents`
// CRITICAL: Headings must use HeadingLevel ONLY - no custom styles
new TableOfContents("Table of Contents", { hyperlink: true, headingStyleRange: "1-3" })
`### Headers/Footers`
sections: [{
  properties: {
    page: { margin: { top: 1440, right: 1440, bottom: 1440, left: 1440 } } // 1440 = 1 inch
  },
  headers: {
    default: new Header({ children: [new Paragraph({ children: [new TextRun("Header")] })] })
  },
  footers: {
    default: new Footer({ children: [new Paragraph({
      children: [new TextRun("Page "), new TextRun({ children: [PageNumber.CURRENT] })]
    })] })
  },
  children: [/* content */]
}]

Critical Rules for docx-js

  • Set page size explicitly - docx-js defaults to A4; use US Letter (12240 x 15840 DXA) for US documents
  • Landscape: pass portrait dimensions - docx-js swaps width/height internally; pass short edge as width, long edge as height, and set orientation: PageOrientation.LANDSCAPE
  • Never use \n - use separate Paragraph elements
  • Never use unicode bullets - use LevelFormat.BULLET with numbering config
  • PageBreak must be in Paragraph - standalone creates invalid XML
  • ImageRun requires type - always specify png/jpg/etc
  • Always set table width with DXA - never use WidthType.PERCENTAGE (breaks in Google Docs)
  • Tables need dual widths - columnWidths array AND cell width, both must match
  • Table width = sum of columnWidths - for DXA, ensure they add up exactly
  • Always add cell margins - use margins: { top: 80, bottom: 80, left: 120, right: 120 } for readable padding
  • Use ShadingType.CLEAR - never SOLID for table shading
  • TOC requires HeadingLevel only - no custom styles on heading paragraphs
  • Override built-in styles - use exact IDs: "Heading1", "Heading2", etc.
  • Include outlineLevel - required for TOC (0 for H1, 1 for H2, etc.)

Editing Existing Documents

Follow all 3 steps in order.

Step 1: Unpack

python scripts/office/unpack.py document.docx unpacked/
Extracts XML, pretty-prints, merges adjacent runs, and converts smart quotes to XML entities (“ etc.) so they survive editing. Use --merge-runs false to skip run merging.

Step 2: Edit XML

Edit files in unpacked/word/. See XML Reference below for patterns.
Use "Claude" as the author for tracked changes and comments, unless the user explicitly requests use of a different name.
Use the Edit tool directly for string replacement. Do not write Python scripts. Scripts introduce unnecessary complexity. The Edit tool shows exactly what is being replaced.
CRITICAL: Use smart quotes for new content. When adding text with apostrophes or quotes, use XML entities to produce smart quotes:
<!-- Use these entities for professional typography -->
<w:t>Here&#x2019;s a quote: &#x201C;Hello&#x201D;</w:t>
Entity
Character
&#x2018;
‘ (left single)
&#x2019;
’ (right single / apostrophe)
&#x201C;
“ (left double)
&#x201D;
” (right double)
Adding comments: Use comment.py to handle boilerplate across multiple XML files (text must be pre-escaped XML):
python scripts/comment.py unpacked/ 0 "Comment text with &amp; and &#x2019;"
python scripts/comment.py unpacked/ 1 "Reply text" --parent 0  # reply to comment 0
python scripts/comment.py unpacked/ 0 "Text" --author "Custom Author"  # custom author name
Then add markers to document.xml (see Comments in XML Reference).

Step 3: Pack

python scripts/office/pack.py unpacked/ output.docx --original document.docx
Validates with auto-repair, condenses XML, and creates DOCX. Use --validate false to skip.
Auto-repair will fix:
  • durableId >= 0x7FFFFFFF (regenerates valid ID)
  • Missing xml:space="preserve" on <w:t> with whitespace
Auto-repair won't fix:
  • Malformed XML, invalid element nesting, missing relationships, schema violations

Common Pitfalls

  • Replace entire <w:r> elements: When adding tracked changes, replace the whole <w:r>...</w:r> block with <w:del>...<w:ins>... as siblings. Don't inject tracked change tags inside a run.
  • Preserve <w:rPr> formatting: Copy the original run's <w:rPr> block into your tracked change runs to maintain bold, font size, etc.

XML Reference

Schema Compliance

  • Element order in <w:pPr>: <w:pStyle>, <w:numPr>, <w:spacing>, <w:ind>, <w:jc>, <w:rPr> last
  • Whitespace: Add xml:space="preserve" to <w:t> with leading/trailing spaces
  • RSIDs: Must be 8-digit hex (e.g., 00AB1234)

Tracked Changes

Insertion:
<w:ins w:id="1" w:author="Claude" w:date="2025-01-01T00:00:00Z">
  <w:r><w:t>inserted text</w:t></w:r>
</w:ins>
`**Deletion:**`
<w:del w:id="2" w:author="Claude" w:date="2025-01-01T00:00:00Z">
  <w:r><w:delText>deleted text</w:delText></w:r>
</w:del>
Inside <w:del>: Use <w:delText> instead of <w:t>, and <w:delInstrText> instead of <w:instrText>.
Minimal edits - only mark what changes:
<!-- Change "30 days" to "60 days" -->
<w:r><w:t>The term is </w:t></w:r>
<w:del w:id="1" w:author="Claude" w:date="...">
  <w:r><w:delText>30</w:delText></w:r>
</w:del>
<w:ins w:id="2" w:author="Claude" w:date="...">
  <w:r><w:t>60</w:t></w:r>
</w:ins>
<w:r><w:t> days.</w:t></w:r>
`**Deleting entire paragraphs/list items** - when removing ALL content from a paragraph, also mark the paragraph mark as deleted so it merges with the next paragraph. Add `<w:del/>` inside `<w:pPr><w:rPr>`:`
<w:p>
  <w:pPr>
    <w:numPr>...</w:numPr>  <!-- list numbering if present -->
    <w:rPr>
      <w:del w:id="1" w:author="Claude" w:date="2025-01-01T00:00:00Z"/>
    </w:rPr>
  </w:pPr>
  <w:del w:id="2" w:author="Claude" w:date="2025-01-01T00:00:00Z">
    <w:r><w:delText>Entire paragraph content being deleted...</w:delText></w:r>
  </w:del>
</w:p>
Without the <w:del/> in <w:pPr><w:rPr>, accepting changes leaves an empty paragraph/list item.
Rejecting another author's insertion - nest deletion inside their insertion:
<w:ins w:author="Jane" w:id="5">
  <w:del w:author="Claude" w:id="10">
    <w:r><w:delText>their inserted text</w:delText></w:r>
  </w:del>
</w:ins>
`**Restoring another author's deletion** - add insertion after (don't modify their deletion):`
<w:del w:author="Jane" w:id="5">
  <w:r><w:delText>deleted text</w:delText></w:r>
</w:del>
<w:ins w:author="Claude" w:id="10">
  <w:r><w:t>deleted text</w:t></w:r>
</w:ins>

Comments

After running comment.py (see Step 2), add markers to document.xml. For replies, use --parent flag and nest markers inside the parent's.
CRITICAL: <w:commentRangeStart> and <w:commentRangeEnd> are siblings of <w:r>, never inside <w:r>.
<!-- Comment markers are direct children of w:p, never inside w:r -->
<w:commentRangeStart w:id="0"/>
<w:del w:id="1" w:author="Claude" w:date="2025-01-01T00:00:00Z">
  <w:r><w:delText>deleted</w:delText></w:r>
</w:del>
<w:r><w:t> more text</w:t></w:r>
<w:commentRangeEnd w:id="0"/>
<w:r><w:rPr><w:rStyle w:val="CommentReference"/></w:rPr><w:commentReference w:id="0"/></w:r>

<!-- Comment 0 with reply 1 nested inside -->
<w:commentRangeStart w:id="0"/>
  <w:commentRangeStart w:id="1"/>
  <w:r><w:t>text</w:t></w:r>
  <w:commentRangeEnd w:id="1"/>
<w:commentRangeEnd w:id="0"/>
<w:r><w:rPr><w:rStyle w:val="CommentReference"/></w:rPr><w:commentReference w:id="0"/></w:r>
<w:r><w:rPr><w:rStyle w:val="CommentReference"/></w:rPr><w:commentReference w:id="1"/></w:r>

Images

  1. Add image file to word/media/
  2. Add relationship to word/_rels/document.xml.rels:
<Relationship Id="rId5" Type=".../image" Target="media/image1.png"/>
  1. Add content type to [Content_Types].xml:
<Default Extension="png" ContentType="image/png"/>
  1. Reference in document.xml:
<w:drawing>
  <wp:inline>
    <wp:extent cx="914400" cy="914400"/>  <!-- EMUs: 914400 = 1 inch -->
    <a:graphic>
      <a:graphicData uri=".../picture">
        <pic:pic>
          <pic:blipFill><a:blip r:embed="rId5"/></pic:blipFill>
        </pic:pic>
      </a:graphicData>
    </a:graphic>
  </wp:inline>
</w:drawing>

Dependencies

  • pandoc: Text extraction
  • docx: npm install -g docx (new documents)
  • LibreOffice: PDF conversion (auto-configured for sandboxed environments via scripts/office/soffice.py)
  • Poppler: pdftoppm for images