hands-on-deck — 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":"replace-color","scope":"deck", "from":"E8A33D", "to":"F8DE6E"},
  {"op":"set-theme",   "colors":{"accent1":"BB7B19"}, "fonts":{"major":"Georgia"}},
  {"op":"set-props",   "title":"Q3 Review", "author":"Acme"},
  {"op":"set-slide",   "slide":3, "hidden":true, "background":"0F5258"},
  {"op":"set-slide",   "slide":3, "transition":{"type":"fade","speed":"med"}},
  {"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, "anchor":"MIDDLE"},
  {"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):

• Vertical centering is anchor, not alignment: alignment (set-text) is HORIZONTAL; to center text in a box taller than the text, set "anchor":"MIDDLE" (TOP|MIDDLE|BOTTOM) on set-style or set-text. inspect reports it when it's not the default top. html2patch sets it automatically from the slide's CSS (flex/grid centering).
• 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.
• Transitions only on request: never add slide transitions unless the user explicitly asks — applied uninvited or inconsistently they're annoying, not polish. When asked, default to one subtle type (fade) across the whole deck.
• Alignment is linted, advisory: inspect/apply report a misaligned issue when a shape's load-bearing edge sits a hair (0.03"–0.15") off a gridline ≥3 other shapes share — the near-miss that reads as sloppy. Act on it (move/resize the edge to the named coordinate) or ignore it: intentional asymmetry is real, so it never fails the build, and apply reports only a newly introduced near-miss.
• 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; <a href> becomes a real hyperlink. 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 look at the render before repairing; run fix only if the render shows a real problem.
• NEVER dismiss an overflow or covered_by flag on display-size text without zooming that exact shape: render --slide N --crop l,t,w,h --scale 2. Serif faces wrap differently in PowerPoint than in the browser — a clipped last line is invisible at thumbnail size, especially when it falls behind a picture.
• 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).

Reviewing more than a slide or two — fan out, don't accumulate

Rendered images and full inspect dumps are the heaviest things you put in context, and they never leave it: one agent that builds the deck and then reviews every slide re-reads every image and dump it has ever seen on every later turn, so cost grows with the square of the work. The fix is context discipline, not fewer checks.

When more than a slide or two needs visual review, AND you have a sub-agent / Task tool available, fan the review out — one sub-agent per slide (or per small batch):

• Give each sub-agent a fresh, minimal context: the deck path + that one slide's render + its inspect --slide N. NOT your build history, the other slides, or their renders. This is the whole point — each review context stays small, and they run in parallel.
• Each sub-agent returns a verdict only — pass, or the specific defects with shape ids and the fix/patch ops to apply. It does not hand the image back to you.
• You apply the fixes from the verdicts, then (if needed) fan out one more round on only the slides that changed.

Even during the build, don't hoard renders in your own thread. Look at a render, act on it, and move on — don't carry a growing pile of slide JPGs forward. If you're visually checking many slides, delegate the looking so the images live in the sub-agents' contexts, not yours.

No sub-agent tool available? Render and review in small batches and drop earlier slides' images from context once you've judged them — same principle, manual.

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, shape animations (slide transitions ARE covered — set-slide "transition"; verify them with inspect/diff, since renders are static), 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)