Two tightly-coupled bugs visible after the PUBLIC_BASE_URL fix landed:
1. Trigger URLs now correctly show :22784 (the host-exposed nginx port),
but opening one in the browser rendered the SPA's NotFound page instead
of hitting the backend trigger handler.
Root cause: dev.nginx only had `location /` → frontend_dev. No location
block for `/c/`, `/k/`, or even `/api/`. Every request went to the SPA;
only `/api/*` happened to work because vite's internal proxy caught it
on its way through frontend_dev → canary. /c/* and /k/* (the trigger
paths) just fell through to the SPA fallback.
Fix: add `upstream canary { server canary:8080 }` to nginx.conf and
three new location blocks in dev.nginx for /api/, /c/, /k/. Each one
proxy_passes directly to the canary upstream with X-Real-IP +
X-Forwarded-For + X-Forwarded-Proto set so middleware.RealIP() resolves
the actual visitor IP rather than the docker bridge. Mirrors what
spec §12.3 prescribes for prod nginx.
2. Manage URL in responses still showed :8080 even after PUBLIC_BASE_URL
was set to :22784. Two separate config keys: canary.base_url
(PUBLIC_BASE_URL → trigger_url) and canary.manage_url (CANARY_MANAGE_URL
→ manage_url). The latter has no env-name overlap with the spec's
PUBLIC_BASE_URL, so it kept its default literal "http://localhost:8080".
Fix: in config.Load(), after unmarshal, fall manage_url back to base_url
when it's empty or still equals the bare default. Operators setting one
env var (PUBLIC_BASE_URL) now get both URLs computed off it. Explicit
CANARY_MANAGE_URL still wins if set — preserves the prod ability to
serve manage at a different domain than triggers. Extracted the literal
to a `defaultCanaryBaseURL` const so the default and the fallback
sentinel reference the same string.
After this + the prior PUBLIC_BASE_URL alias, a fresh token from the form
should produce trigger_url + manage_url both pointing at
http://localhost:${NGINX_HOST_PORT}/... — clickable, reachable, and triggers
hitting /c/ now route to canary and record events.
Operator action: just dev-down && just dev-up to rebuild nginx + canary
containers with the new config.