skills/pptx-generator/references/editing.md

Editing Existing Presentations

Template-Based Workflow

When using an existing presentation as a template:

1. Copy and analyze:

   cp /path/to/user-provided.pptx template.pptx
   python -m markitdown template.pptx > template.md
   

   Review template.md to see placeholder text and slide structure.

2. Plan slide mapping: For each content section, choose a template slide.

   USE VARIED LAYOUTS — monotonous presentations are a common failure mode. Don't default to basic title + bullet slides. Actively seek out:

   • Multi-column layouts (2-column, 3-column)
   • Image + text combinations
   • Full-bleed images with text overlay
   • Quote or callout slides
   • Section dividers
   • Stat/number callouts
   • Icon grids or icon + text rows

   Avoid: Repeating the same text-heavy layout for every slide.

   Match content type to layout style (e.g., key points -> bullet slide, team info -> multi-column, testimonials -> quote slide).

3. Unpack: Extract the PPTX into an editable XML tree using Python's zipfile module. Pretty-print the XML for readability.

4. Build presentation (do this yourself, not with subagents):

   • Delete unwanted slides (remove from <p:sldIdLst>)
   • Duplicate slides you want to reuse (copy slide XML, relationships, and update Content_Types.xml and presentation.xml)
   • Reorder slides in <p:sldIdLst>
   • Complete all structural changes before step 5

5. Edit content: Update text in each slide{N}.xml. Use subagents here if available — slides are separate XML files, so subagents can edit in parallel.

6. Clean: Remove orphaned files — slides not in <p:sldIdLst>, unreferenced media, orphaned rels.

7. Pack: Repack the XML tree into a PPTX file. Validate, repair, condense XML, re-encode smart quotes.

   Always write to /tmp/ first, then copy to the final path. Python's zipfile module uses seek internally, which fails on some volume mounts (e.g. Docker bind mounts). Writing to a local temp path avoids this.

Output Structure

Copy the user-provided file to template.pptx in cwd. This preserves the original and gives a predictable name for all downstream operations.

cp /path/to/user-provided.pptx template.pptx

./
├── template.pptx               # Copy of user-provided file (never modified)
├── template.md                 # markitdown extraction
├── unpacked/                   # Editable XML tree
└── edited.pptx                 # Final repacked deck

Minimum expected deliverable: edited.pptx.

Slide Operations

Slide order is in ppt/presentation.xml -> <p:sldIdLst>.

Reorder: Rearrange <p:sldId> elements.

Delete: Remove <p:sldId>, then clean orphaned files.

Add: Copy the source slide's XML file, its .rels file, and update Content_Types.xml and presentation.xml. Never manually copy slide files without updating all references — this causes broken notes references and missing relationship IDs.

Editing Content

Subagents: If available, use them here (after completing step 4). Each slide is a separate XML file, so subagents can edit in parallel. In your prompt to subagents, include:

• The slide file path(s) to edit
• "Use the Edit tool for all changes"
• The formatting rules and common pitfalls below

For each slide:

1. Read the slide's XML
2. Identify ALL placeholder content — text, images, charts, icons, captions
3. Replace each placeholder with final content

Use the Edit tool, not sed or Python scripts. The Edit tool forces specificity about what to replace and where, yielding better reliability.

Formatting Rules

• Bold all headers, subheadings, and inline labels: Use b="1" on <a:rPr>. This includes:
  • Slide titles
  • Section headers within a slide
  • Inline labels like (e.g.: "Status:", "Description:") at the start of a line
• Never use unicode bullets: Use proper list formatting with <a:buChar> or <a:buAutoNum>
• Bullet consistency: Let bullets inherit from the layout. Only specify <a:buChar> or <a:buNone>.

Common Pitfalls — Template Editing

Template Adaptation

When source content has fewer items than the template:

• Remove excess elements entirely (images, shapes, text boxes), don't just clear text
• Check for orphaned visuals after clearing text content
• Run content QA with markitdown to catch mismatched counts

When replacing text with different length content:

• Shorter replacements: Usually safe
• Longer replacements: May overflow or wrap unexpectedly
• Verify with markitdown after text changes
• Consider truncating or splitting content to fit the template's design constraints

Template slots != Source items: If template has 4 team members but source has 3 users, delete the 4th member's entire group (image + text boxes), not just the text.

Multi-Item Content

If source has multiple items (numbered lists, multiple sections), create separate <a:p> elements for each — never concatenate into one string.

WRONG — all items in one paragraph:

<a:p>
  <a:r><a:rPr .../><a:t>Step 1: Do the first thing. Step 2: Do the second thing.</a:t></a:r>
</a:p>

CORRECT — separate paragraphs with bold headers:

<a:p>
  <a:pPr algn="l"><a:lnSpc><a:spcPts val="3919"/></a:lnSpc></a:pPr>
  <a:r><a:rPr lang="en-US" sz="2799" b="1" .../><a:t>Step 1</a:t></a:r>
</a:p>
<a:p>
  <a:pPr algn="l"><a:lnSpc><a:spcPts val="3919"/></a:lnSpc></a:pPr>
  <a:r><a:rPr lang="en-US" sz="2799" .../><a:t>Do the first thing.</a:t></a:r>
</a:p>
<a:p>
  <a:pPr algn="l"><a:lnSpc><a:spcPts val="3919"/></a:lnSpc></a:pPr>
  <a:r><a:rPr lang="en-US" sz="2799" b="1" .../><a:t>Step 2</a:t></a:r>
</a:p>
<!-- continue pattern -->

Copy <a:pPr> from the original paragraph to preserve line spacing. Use b="1" on headers.

Smart Quotes

The Edit tool converts smart quotes to ASCII. When adding new text with quotes, use XML entities:

<a:t>the &#x201C;Agreement&#x201D;</a:t>

Character	Name	Unicode	XML Entity
\u201c	Left double quote	U+201C	“
\u201d	Right double quote	U+201D	”
\u2018	Left single quote	U+2018	‘
\u2019	Right single quote	U+2019	’

Other

• Whitespace: Use xml:space="preserve" on <a:t> with leading/trailing spaces
• XML parsing: Use defusedxml.minidom, not xml.etree.ElementTree (corrupts namespaces)