A pass over the content at startup writes three widths per picture into a cache
outside the site root, named by the source's content hash and the width (ADR-0042).
Idempotent by construction: a rerun stats and skips, an edited picture takes a new
name, and nothing stale can be served under an old one. Restarting the evidence
site made 0 derivatives the second time, as it should.
Ahead of the request rather than during it, because resampling is felt and there is
no page cache yet to hide it. Outside the site root, because the engine reads that
directory and must not leave generated files in somebody's content git — a lost
cache costs one startup pass and no correctness.
Markup now carries the original as src, the derivatives as srcset closed by the
original at its own width, and width/height from the original — which retires most
of the latent row about the output floor; only a gallery's alt is still empty, and
a filename cannot supply that.
Two things the work itself decided:
`Fragment.Items` became `Fragment.Pictures`, ADR-0037's own revisit trigger. Items
had one consumer, so widening it beat adding a second list beside it.
"A browser can show it" and "we can resample it" are different questions, and
conflating them nearly deleted content: an SVG has no decoder here, so a single
predicate would have dropped SVGs from galleries silently. Undecodable and
unsupported pictures are now rendered as they are, without a size or a srcset.
Every figure and gallery shipped so far emitted links a browser could not fetch: a
relative src resolves under the page's URL, and nothing answered there. Found by
fetching the pages' own links rather than by reading their markup — the evidence
runs had been checking that the right src appeared, never that it worked.
A directory bundle's files are now served under its URL. The bundle is looked up
first and the file is read only from the directory that bundle owns, never from a
path assembled out of the request: ADR-0024 requires that no route serve bundle
bytes by path alone, since every byte inside a bundle inherits its publish status.
When drafts arrive at queue 19 the filter belongs beside that lookup and nowhere
else, which is why the ordering is written down in the comment.
A single-file bundle owns nothing: its neighbours belong to the section, and its
slash-terminated URL has nothing beneath it. An author with assets writes a
directory bundle, now stated in content-model.md.
A .md inside a bundle directory is never an asset — it is a bundle with its own URL
or a fragment that was never addressable, and serving either raw would publish
source. http.ServeFileFS handles content type, conditional requests and ranges,
none of which is worth reimplementing here.
bdeshi