A single result can have several representations
A notebook display output can contain a MIME bundle: a PNG picture, HTML table and plain text may all describe the same result. This publisher chooses one supported representation in a fixed order to avoid printing the same result several times. The manifest keeps the available types and the chosen type for each output.
PNG and JPEG bytes are checked for recognizable format and bounded dimensions before they are decoded. A saved HTML table becomes plain table values. CSS, links, scripts and merged-cell geometry are not preserved. Stream output and saved errors remain text, including the original error message rather than an invented successful result.
A safe preview is not a notebook runtime
Raw HTML embedded in Markdown is displayed as literal source. Rich HTML output is reduced to new text and table structures; it is not inserted as an original document. External images, stylesheets, iframes, JavaScript, SVG and widget runtimes are never requested or executed because a file asks for them.
An interactive chart may still have a useful saved PNG alternative. If it does not, export a static chart in the notebook and save again. The converter cannot reconstruct a widget state by guessing what the original Python code would have produced. Missing representations are visible omissions and appear in the export notes.
Inspect privacy separately from execution safety
Preventing scripts from running does not make the contents suitable for public sharing. A code cell can contain access tokens, a traceback can reveal a local path, and a table can contain personal records. Use the preview to remove the relevant cells before generating the final selection.
The exported HTML is self-contained and contains no executable notebook scripts. It still contains the selected report data and embedded images. Treat the PDF, HTML and manifest as potentially sensitive documents. The original notebook is never modified, and withdrawing a cell from a later export does not erase an earlier downloaded file.