Polling lives in internal/ext/watch, per the human's call to keep core under its
ceiling rather than raise it a second time — which is what ADR-0041 said a second
raise would mean. It is a poller, deletable without trace, and core stayed at
2671/2800.
A settled change calls the same `rebuilder` that startup calls, because a reload
path that differs from the startup path is a reload path that drifts. The index is
an atomic.Pointer swapped whole, so a request reads the site that was current when
it arrived instead of one being rebuilt underneath it — the alternative, mutating in
place, is a data race with every in-flight request.
Names, sizes and modification times, not contents: reading every file to detect a
change costs more than the rebuild it triggers. Editor droppings are excluded,
because saving in vim writes a swap file, a backup and the number 4913, and each
would otherwise look like a change. A change must hold still for a moment first,
since one save is often several operations.
Verified against the running binary: a page 404s, the file appears, and five seconds
later it serves — one "site root changed" in the log. Then three droppings written
at once produced no rebuild at all.
Two warnings fired and were fixed rather than silenced: `runServe` gave up the
rebuild closure to `rebuilder`, and the fingerprint walk gave up its body to
`record`, where three exclusions read as a list instead of as nesting.
The Dockerfile ships the binary alone. The site root arrives as a volume and is
never copied in — it is somebody's content repository with its own history
(ADR-0011), so the image is the same for every site.
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.
Two exact paths a crawler asks for by name, so they are mux entries rather than
resolver cases — no bundle can collide, since a key always sits under a section.
robots.txt at the site root is served verbatim, because a site that ships one has
said something deliberate; otherwise the engine emits the minimum that is true and
points at the sitemap. The sitemap lists every bundle in every language it exists
in, since each variant is separately reachable, with lastmod only where a bundle
has a date. Every URL comes from content.URL like every other path the engine
emits, so a sitemap cannot disagree with what is actually served.
Both need a declared base. Without one the sitemap answers 404 rather than listing
paths no crawler can resolve, and robots omits the Sitemap line rather than
writing a relative one.
write() was setting text/html for every caller, and headers only go out with the
first byte — so a handler setting its own type would have had it silently replaced,
which is how a sitemap gets served as a web page. It now splits into write and
writeAs, and the tests assert the content types rather than only the bodies.
bdeshi