deckhand

name

deckhand

description

Use this skill any time a .pptx file is involved in any way — as input, output, or both. This includes reading, analyzing, or extracting content from presentations; editing text, images, styles, or layout of existing decks; creating new slides, shapes, tables, or pictures; reordering, duplicating, or merging slides across decks; and verifying decks visually. Trigger whenever the user mentions a deck, slides, a presentation, or a .pptx filename.

deckhand — agent-native PPTX manipulation

One tool does everything: scripts/deck.py. You write a JSON patch describing your edits; deck.py validates and executes it atomically, then lints the result. You never need to open slide XML for routine work.

Golden rules (the tool enforces and repeats these):

• ALL slide indices are 0-based, everywhere. Shapes are addressed by stable native ids (s12) or unique shape name.
• Positions and sizes are inches from the slide's top-left.
• Patches are atomic: every op is pre-validated (all errors reported at once, with the slide's real shape listing), then applied all-or-nothing.

Full reference: python scripts/deck.py docs — prints every op with semantics and recipes; needs no file. Read it before writing your first patch.

The edit loop

# 1. READ — cheap orientation first, full JSON only when about to write a patch
python scripts/deck.py deck.pptx inspect --slide 3 --brief   # one line per shape
python scripts/deck.py deck.pptx inspect --slide 3           # full JSON: text+formatting, image rIds, geometry, issues
python scripts/deck.py deck.pptx inspect --issues            # only shapes with geometric problems

# 2. WRITE — one patch, many ops, atomic; chain repair + render of touched slides
python scripts/deck.py deck.pptx apply patch.json -o out.pptx --fix --render img/

# 3. VERIFY — look at what you changed
#    (render names files slide-<0-based-index>.jpg to match inspect)
python scripts/deck.py deck.pptx diff out.pptx               # structural changelog, no rendering

--fix runs deterministic geometry repair on the slides you touched (grows/shrinks/nudges overflowing text; never auto-moves pictures). Its residue report lists what still needs judgment, with a suggested op. Always look at the rendered image before declaring success.

Patch ops at a glance

{"ops": [
  {"op":"set-text",    "slide":3, "shape":"s12", "text":["Title", "Subtitle"]},
  {"op":"swap-image",  "slide":3, "shape":"s9",  "image":"/abs/new.png"},
  {"op":"swap-image",  "media":"image13.png",    "image":"/abs/logo.png"},
  {"op":"replace-text","scope":"deck", "from":"Old Name", "to":"New Name"},
  {"op":"set-notes",   "slide":3, "notes":"speaker notes"},
  {"op":"move",        "slide":3, "shape":"s12", "to":[1.0,2.5]},
  {"op":"resize",      "slide":3, "shape":"s12", "size":[4.0,1.5]},
  {"op":"set-style",   "slide":3, "shape":"s12", "font_size":18, "fill":"0B3D3A", "rotation":6},
  {"op":"delete",      "slide":3, "shape":"s12"},
  {"op":"duplicate",   "slide":3, "shape":"s12", "offset":[0,1.2], "text":["Fourth pillar"]},
  {"op":"copy-shape",  "from_slide":8, "shape":"s12", "slide":3, "at":[1.0,2.0]},
  {"op":"reorder",     "slide":3, "shape":"s12", "z":"back"},
  {"op":"add-shape",   "slide":3, "kind":"textbox", "at":[1,2], "size":[4,1.5], "text":["…"], "name":"card"},
  {"op":"add-picture", "slide":3, "image":"/abs/img.png", "at":[1,2], "width":4},
  {"op":"add-table",   "slide":3, "at":[1,2], "size":[8,3], "rows":[["A","B"],["1","2"]]},
  {"op":"add-slide",   "layout":"Blank", "at":5},
  {"op":"add-row",     "slide":3, "shape":"s12", "cells":["a","b"]},
  {"op":"delete-col",  "slide":3, "shape":"s12", "col":1}
]}

Key semantics (details in docs):

• set-text inherits formatting: new paragraph i inherits ALL formatting of old paragraph i — pass plain strings for routine replacement. Pass objects to override ({"text":"Big","font_size":28}), or "runs" for mixed in-paragraph formatting. Table cells: add "cell":[row,col].
• Prefer duplicate/copy-shape over add-shape when a styled donor exists — new shapes start from PowerPoint defaults, not the deck's design language.
• add-shape "name" lets later ops in the same patch target the shape it creates.
• Keep new text comparable in length to the old, or let fix repair the overflow.

Creating slides from HTML (html2patch)

When a slide should be DESIGNED from scratch — free-form layout, no styled donor to duplicate — write it as HTML/CSS and compile it into a patch. The browser is used as a measuring engine; the output is ordinary deck.py ops.

Before writing any slide HTML, read designing-slides.md — how to design for this medium: subject-derived palettes, refusing the default AI-deck looks, the token plan, projection type sizes, and what survives compilation. The pipeline below is mechanical; that file is taste.

python scripts/html2patch.py slide.html --deck deck.pptx --layout Blank -o patch.json
python scripts/deck.py deck.pptx apply patch.json -o out.pptx --render img/

• The <body> is the slide at 96px/inch: 16:9 → width:1280px; height:720px. Content overflowing the body is a compile error.
• Text lives in <p>, <h1>–<h6>, <ul>/<ol> (numbered), <table>, or any element with inline-only content (figcaption, blockquote…). Divs with background / border / border-radius / linear-gradient become styled rects; <img> becomes a picture (local files only; object-fit: cover becomes a real crop); <table> becomes a real table with per-cell fills and measured column widths.
• Inline <b>/<i>/<u>/<span style> become formatted runs. CSS padding maps to text insets; text-transform, transform:rotate, and vertical writing-mode are honored. Use installed fonts (Arial, Georgia, …).
• By default each HTML file appends a new slide (add-slide, --layout picks the template layout); --slide N targets an existing slide instead. Multiple files compile into ONE atomic patch.
• Apply compiled patches WITHOUT --fix first — geometry is browser-measured, so trust the render and look at it; run fix only if the render shows a real problem.
• Extra dependency: pip install playwright && playwright install chromium.

Deck structure (subcommands, not patch ops)

python scripts/deck.py deck.pptx slides 0,3,3,5 -o out.pptx        # keep these, in this order; repeat = duplicate
python scripts/deck.py deck.pptx merge module.pptx --slides 0,2 --at 12 -o out.pptx
python scripts/deck.py deck.pptx merge --list-layouts              # choose a layout for imported slides

Building a deck from a template (the human workflow)

1. slides the template down to the target slide sequence (duplicating repeated layouts).
2. merge in any reusable modules.
3. One replace-text patch for global renames (scope master catches footers).
4. Per-slide patches: inspect --slide N for shape ids, then set-text / swap-image only what you name — nothing else is touched.
5. apply --fix --render img/ and look at every touched slide.

Verification

• render -o img/ --slide 3,7 — JPGs named slide-<index>.jpg; --crop l,t,w,h --scale 2 zooms a region (inches, same coordinates as inspect). Hidden slides render only when explicitly listed.
• diff other.pptx — text/geometry/media/notes changelog without rendering.
• Thumbnail grids for whole-deck review: python scripts/thumbnail.py deck.pptx --cols 4 (optional second arg = output filename prefix).

Escape hatch

When no op expresses the change (animations, exotic effects):

python scripts/deck.py deck.pptx xml get --slide 5 -o slide5.xml   # pretty-printed, editable
python scripts/deck.py deck.pptx xml set slide5.xml --slide 5 -o out.pptx   # parse-checked, lint-checked

Out of scope by design (use the escape hatch or PowerPoint itself): creating native charts, animations, transitions, embedded video/OLE, merged table cells.

Dependencies

• Python 3.9+ with python-pptx and Pillow (pip install python-pptx Pillow)
• For render and thumbnails: LibreOffice (soffice) and Poppler (pdftoppm)