Built on #306's storage, serving and crop control — a layer, not a parallel
implementation. `resolveBranding` in shared is the ONE place that answers
"which asset applies here?", and both the sidebar logo and the favicon swap
read it.
The decision most likely to be "fixed" by accident, so it is pinned by name
in `branding.test.ts`: **a logo set belongs to one level and variants are
never mixed across levels.** A pond that uploaded only a light logo shows THAT
logo in dark mode; it does not borrow the instance's dark variant. Decided
2026-08-01 — a logo silently swapping to a different image when the viewer
switches theme is a change nobody ordered, and a design that looks wrong is
more honest than one that is quietly substituted. Only a pond with no logo at
all inherits the instance's set, again as a set. The settings screen warns
about a missing dark variant; it never blocks.
Consequences that fall out of that rule and are easy to get wrong:
- The serving route does NOT fall back when given a pond scope. The caller
already decided which level applies; a "helpful" fallback in the route
would mix variants across levels behind the resolver's back.
- The logo link's accessible name follows the LEVEL: a pond logo is named by
the pond, an instance logo by the instance. It is the link home, and a
link's name has to say where it goes.
- **Charged to the pond's storage quota**, before the write, like attachments.
Without it branding would be a way around the quota, and replacing a logo
repeatedly would consume disk with no ceiling. The replaced asset's bytes
are released FIRST, so re-uploading the same logo costs nothing — and a
refused upload puts the released reservation back, so a rejection cannot
leave the pond with more room than it had.
- **Purge removes the branding files.** The purge standard is absolute: after
it nothing referencing the pond survives, rows or files. Asserted against
the real purge path, not the new code alone.
- Security unchanged from #306 and not relaxed because the uploader is now an
ordinary Pond Admin: SVG refused, magic bytes and IHDR checked server-side,
size caps, content type pinned, no image parsing.
- The favicon swap is driven by the RESOLVED pond, never the raw route
parameter — an unreadable or unknown slug must not leave a stale icon in
the tab. That it happens after first paint is accepted and stated in the
code and the UI: avoiding it would mean server-rendering index.html, which
is #179's territory.
Same audit id as #306 (`branding.changed`) with `scope: 'pond'` — the catalogue
already carries the field, so no version bump.
Verified: api suite 105 files / 592 tests green; 5 pond-branding e2e tests
(pond scope serves the pond's bytes while the instance level still 404s, the
quota is charged and released exactly, SVG refused at pond level, a reader may
read but not change, purge deletes the files); 9 shared unit tests on the
resolution order including both mixing directions.
Claude Opus 5
90748b743e