pptx-html docs

pptx-html moves slides between HTML and PPTX by driving @shbernal/ts-pptx. It owns the HTML ⇄ ts-pptx link, in both directions. It does not emit OOXML itself, and it does not generate the HTML.

These pages are the design record: the why. The README is the introduction, and CONTRIBUTING is how to build, test and verify a change.

Page	What it answers
Invariant R and the round-trip oracle	What the project guarantees, and the harness that gates it
Architecture	The two lanes, the two models, and the rules each part is built on
Decisions that must not be undone	Two capabilities that were removed on purpose

The shape of it in one screen

.pptx  ──import──►  IR  ──render──►  HTML   (what a human sees / edits)
  ▲                  ▲                 │
  └────emit──────────┴─────parse───────┘   (what a machine reads back)

Four legs, one loop, over a paint model that is embedded in the rendered document as a JSON island. The return path parses that island, never getComputedStyle, which is what lets the visible SVG approximate freely without any of that approximation reaching the emitted deck.

A second, secondary lane (convertDeck / convertSlide) infers a model from a rendered DOM, for HTML this library did not produce. It is browser-only, best-effort, and shares no code path with the loop.