Docx authoring

docx-authoring

Wing-1 engineering skill for writing Word documents — the generation half of the read→write cycle whose read side is markitdown. Ships zero runtime in this package: the agent drives a library the consumer already has (python-docx, or a zip+XML toolchain), exactly as markitdown wraps a consumer-installed converter. Re-implements the pattern, never any proprietary source.

When to use

• "Generate a .docx report / letter / contract from this content."
• "Fill this Word template with these values."
• "Edit the body of this .docx" (a heading, a table cell, a style).

Do NOT use for: reading a docx → Markdown (that is markitdown); slide decks (html-deck, or the gated pptx surface); PDFs (pdf-tools).

Procedure

1. Pick the path by task

Task	Path
Create from scratch / structured content	Library create (python-docx Document()) — build paragraphs, tables, styles programmatically
Fill a supplied template	Open the template, replace placeholder runs in place, save a copy — never mutate the original
Surgical edit of existing body	unpack → edit XML → pack-with-validate: a .docx is a ZIP of XML; unzip, edit word/document.xml, re-zip preserving the archive structure

2. Honor the hard-won gotchas (encode as rules, not hope)

• Page size defaults to US Letter in most libraries — set A4 explicitly when the locale needs it; never assume.
• Table columns need dual widths — set BOTH the table grid width and each cell width, or renderers ignore one and collapse the layout.
• No Unicode bullet glyphs as literal characters (•, ‣) — use the list-style paragraph, or the document loses its list semantics and screen readers skip it.
• Runs, not paragraphs, carry formatting — a placeholder that spans two runs will not match a naive whole-paragraph replace; split/merge runs first.

3. Validate — round-trip, do not trust the write

1. Re-open the generated file with the SAME library; assert it parses (a corrupt ZIP or malformed XML throws here).
2. Read back one written value (a heading text, a table cell) and assert it equals what was written.
3. For the unpack→pack path: confirm the archive still contains [Content_Types].xml and word/document.xml (dropping either produces a file Word refuses to open).

Output format

1. The generated/edited .docx path.
2. The validation result: parses ✅, read-back value matched ✅, required parts present ✅.
3. Any gotcha that applied (e.g. "set A4 explicitly; template used Letter").

Gotcha

The most common silent failure is a file that saves without error but Word refuses to open: an unpack→pack cycle that re-zipped with a directory entry, wrong compression, or a dropped [Content_Types].xml. The round-trip re-open in step 3 is the only check that catches it — a green "file written" line does not.

• Silent corruption: an unpack→pack cycle re-zipped with a directory entry or a dropped [Content_Types].xml → saves fine, Word shows "file is corrupt". Only the round-trip re-open catches it.

Do NOT

• Do NOT bundle or ship a Python toolkit in this package — drive the consumer's library (zero-runtime posture, like markitdown).
• Do NOT mutate a supplied template in place — always write a copy.
• Do NOT claim success on "file written"; claim it only after the round-trip re-open.
• Do NOT reach for LibreOffice/soffice — that dependency is gated (pptx surface).

Related Skills

WHEN to use this

• The target artifact is a Word .docx — a report, letter, contract, or a filled template.
• A .docx body needs a surgical edit (heading, table cell, style) via the unpack→edit→pack path.

WHEN NOT to use this

• Reading a docx into the conversation → markitdown.
• PDFs → pdf-tools; spreadsheets → spreadsheet-authoring; slide decks → html-deck.
• The task needs LibreOffice-backed rendering (pptx) — that surface is gated, do not reach for it here.

When the agent should load this

• "Generate a Word report from this content."
• "Fill this .docx template with these values."
• "Edit the heading / a table cell in this .docx."
• "Produce a contract as a .docx."

Output

1. Generated document — the .docx path. Cite as docx-output.
2. Validation receipt — parses on re-open ✅, read-back value matched ✅, required OOXML parts present ✅. Cite as docx-validation.
3. Gotcha log — present only when a gotcha applied (page-size override, run-split for a template placeholder). Cite as docx-gotchas.