Module slots 

Generation slot markers («FILL: …» / «IMG: …») — render-time resolution.

Mako’s app generator marks brand-identity fields it cannot know as fill slots («FILL: what it is | a realistic default») and references images only as slots («IMG: description of the image»). The markers stay RAW in the committed site/index.surf so they remain editable; this module resolves them in the FINAL rendered HTML only (called from crate::render_html::render_site_page and crate::render_html::render_site_single_file).

The pass is a linear scanner over the rendered document with a small context state machine (text / inside-tag / script-style raw text). The output HTML is machine-generated and well-formed — escape_html bans raw < in text and attribute values — so the classification is sound:

• «FILL: label | default» → the default text (label when the default segment is missing or empty), in every context. | is the primary separator; when it is absent a spaced em-dash (label — default) is accepted as a fallback separator.
• «IMG: description» in text → <img class="surfdoc-img-slot" src=[IMG_SLOT_PLACEHOLDER_URI] alt="description" loading="lazy">.
• «IMG: description» inside a tag (src="…", style="…url('…')…") → the bare placeholder URI.
• «IMG: description» inside <script>/<style> content (JSON-LD etc.) → the description text only; never a tag.

Unterminated or malformed markers are left verbatim.

Constants

IMG_SLOT_PLACEHOLDER_URI

Placeholder image for unresolved «IMG:» slots: a self-contained SVG data URI (neutral surface, sun + mountains glyph).

Functions

resolve_slot_markers

Resolve generation slot markers in rendered HTML. See the module docs for the marker grammar and per-context behavior. Returns the input unchanged (no allocation beyond the move) when it contains no «.