Skill: slide-edit

Edit an existing generated presentation. Reads the current PPTXGenJS code, applies the requested changes, and regenerates the PPTX file.

Prerequisite: The presentation must be generated first using the slide-generate skill.

Workflow

Step 1 — Accept Input

Gather from the user (ask if not provided):

• Presentation name: Which presentation to edit (list available presentations in slide-workspace/presentations/ if unsure)
• Edit description: What changes to make (e.g., "change title font to red", "add a chart on slide 3", "remove slide 5")

Step 2 — Verify Presentation Workspace

Check that the presentation workspace exists and contains the required files:

slide-workspace/presentations/{presentation-name}/
  code.js      ← required (current code to edit)
  outline.md   ← reference for slide structure

If missing, inform the user to run slide-generate first.

Step 3 — Identify Template Used

Determine which template was used for this presentation:

1. Check preamble.js (if exists) for comments like // Template: template-name
2. Check code.js for defineSlideMaster calls or image references that match a template name
3. If still unclear, ask the user which template was used

The template workspace is at: slide-workspace/templates/{template-name}/

Step 4 — Read Current State

Read from the presentation workspace:

• code.js — the current complete PPTXGenJS code
• outline.md — slide structure reference

Read from the template workspace:

• context.json — template structure data
• guideline.md — design rules
• sample_code.js — style reference

List all files in slide-workspace/templates/{template-name}/images/ to get available image filenames.

Step 5 — Read Prompt Rules

Read prompt rules from:

• shared/prompts/edit-rules.md — editing-specific rules
• shared/prompts/shared-pptxgenjs-rules.md — shared generation rules

Read the API reference from shared/docs/pptxgenjs-api.md.

Step 6 — Apply Edit

Using edit-rules.md as system instructions, generate the COMPLETE updated PPTXGenJS code:

Provide as context:

• Current code.js content
• User's edit description
• Template guideline.md
• Template context.json (with background_color fields)
• sample_code.js reference
• Available image filenames

Key editing rules:

• Output the COMPLETE updated code (not a diff or partial code)
• Preserve the overall template style unless user asks to change it
• Make ONLY the requested changes
• Keep pptx.writeFile({ fileName: 'output.pptx' }) at the end
• Preserve fill.transparency values
• Never re-declare the images variable

Step 7 — Save Updated Code

Back up the old code first:

slide-workspace/presentations/{presentation-name}/code.js.bak

Write the updated code to:

slide-workspace/presentations/{presentation-name}/code.js

Step 8 — Check Dependencies

Check that pptxgenjs is available:

node -e "require('pptxgenjs')" 2>/dev/null

If it fails, run the setup script:

• Unix/macOS: bash shared/scripts/setup_deps.sh
• Windows: powershell -ExecutionPolicy Bypass -File shared/scripts/setup_deps.ps1

Step 9 — Regenerate PPTX

Generate a timestamped output filename in output-YYYYMMDD-HHmmss.pptx format (use the current date/time):

Execute the updated code:

node shared/scripts/run_pptxgenjs.js \
  "slide-workspace/presentations/{presentation-name}/code.js" \
  "slide-workspace/templates/{template-name}/images" \
  "slide-workspace/presentations/{presentation-name}/output-{timestamp}.pptx"

Step 10 — Report Result

Report to the user:

• Changes made (brief summary)
• Output file: slide-workspace/presentations/{presentation-name}/output-{timestamp}.pptx
• Any warnings from the runner
• Note: previous code backed up to code.js.bak

Error Handling

• Presentation not found: Prompt user to run slide-generate first
• Template not identifiable: Ask user which template was used
• Runner exits with code 3: JavaScript error in generated code — inspect the error and offer to fix
• Runner exits with code 4: No .pptx produced — check that pptx.writeFile() is present
• Revert needed: User can restore from code.js.bak if the edit made things worse

Multiple Edits

For multiple sequential edits:

• Each edit reads the CURRENT code.js (already incorporating previous edits)
• The backup (code.js.bak) always reflects the PREVIOUS state before the latest edit
• The outline.md is not automatically updated — if slide structure changes significantly, update it manually or ask the user if they want the outline updated

Notes

• The images variable is pre-injected by run_pptxgenjs.js — never re-declare it
• Each slide's background_color from context.json is the definitive background — always set it explicitly
• Layout images from slide_layouts[layout_index].images must be present on every slide using that layout
• Preserve fill.transparency values — do not drop transparency when editing shapes