| name | lumen-slides-export |
| description | Export a generated lumen slide deck HTML to editable PowerPoint (.pptx). Invoked after lumen-slides produces a deck, or standalone via lumen-export-slides CLI. Preserves vector SVGs and native text boxes. |
| version | 0.1.7 |
lumen-slides-export
Export a lumen slide deck HTML to a fully editable .pptx file using Playwright + dom-to-pptx.
Tier: capability (atomic) — does not invoke other lumen skills. Composites and playbooks may invoke it.
When to invoke
Trigger phrases: export slides, slides to pptx, pptx export, powerpoint export, deck to pptx.
Pipeline
- Verify HTML exists — confirm the slide deck HTML file path is valid.
- Run CLI — invoke
lumen-export-slides <html-path> (or npx lumen-export-slides <html-path> if local bin is not on PATH).
- Report path — return the generated
.pptx file path to the user.
Quality checks
- PPTX file is non-empty and readable by PowerPoint / Keynote / LibreOffice
- SVG diagrams (Mermaid, fgraph) are preserved as vectors when possible
- All slides from the HTML are represented in the PPTX
Validation (M02-S03)
The export pipeline now runs automatic validation in headless Chromium before conversion. Validation detects:
- Overflow — any element's bounding rect exceeds the 1280×720 slide bounds.
- Descender clipping — text nodes where bottom edge exceeds slide bottom with non-zero line-height variance.
- Unwrapped text nodes — bare text nodes directly inside
.slide (not inside <p>, <span>, <h*>, <li>).
- Emoji usage — unicode emoji ranges in text content (PPTX compatibility risk).
Validation warnings are logged to stderr; export proceeds regardless (best-effort fidelity). Structural issues are reported immediately without retry. Transient failures (font loading, Mermaid rendering timeouts) retry up to 3 times with a 2-second delay.
CSS-to-PPTX bridging
- CSS scoping per slide — all stylesheet rules are prefixed with a slide-specific
[data-slide-index="N"] selector before export to prevent class bleed across slides.
- Pseudo-element materialization —
::before and ::after pseudo-elements with non-empty content are converted into real DOM nodes with cloned computed styles before export.
- Canvas normalization — slides are forced to exactly 1280×720 pixels,
100vh/100dvh units are overridden, and scroll-snap/animations are disabled.
Known fidelity limits
The following features are deferred to future work:
- Google Fonts base64 embedding — current templates use system-font fallbacks.
- Baking CSS
filter / opacity to canvas — niche use case, lossy, very complex.
- Auto-regeneration of slides on validation failure — validation reports issues; fixing them is the author's responsibility.
Output
Single .pptx file written alongside the HTML (or to --output if specified). Automatic versioning: if deck.pptx exists, creates deck_v2.pptx, etc.
Notes
- Playwright Chromium browser is downloaded on first run (~3 MB). If browser is missing, the CLI emits:
run "npx playwright install chromium".
