The subscription notifier elects one leader via a host-local flock
(THERMOGRAPH_SINGLETON_LOCK) so multiple uvicorn workers on one host don't
each run it. Under multi-host Swarm that guard is insufficient: each host
would independently elect its own leader, multiplying Open-Meteo quota use
N-fold again.
Add claim_pg(key) alongside the existing claim(lock_path): a cluster-wide
Postgres advisory lock, visible to every host talking to the same database.
The holding connection is dedicated and kept for the process lifetime
(advisory locks are session-scoped); a dead connection is dropped and
re-election retried on the next call.
claim_leader() dispatches between the two mechanisms from env:
THERMOGRAPH_SINGLETON_PG (+ Postgres) -> claim_pg; else
THERMOGRAPH_SINGLETON_LOCK -> claim; else always leader, unchanged. Wired in
at web/app.py in place of the direct claim() call. Off by default, so
today's single-host behavior is unaffected.
* Centralize filesystem paths in a single module
Add paths.py, which resolves the repo root once and derives the cache,
accounts DB, logs, templates, frontend and bundled-city-data locations
from it. Replace the 13 per-module `dirname(__file__)/..` anchors with
references to it, so a module's location no longer determines where the
app reads its data. Env overrides (accounts DB, VAPID, IndexNow) are
unchanged; every resolved path is byte-identical to before.
Groundwork for moving modules into packages without re-pointing paths.
Claude-Session: https://claude.ai/code/session_01XXxmNFy9cZ6Gh8Y9thZn62
* Split the backend into domain packages
Group the flat backend modules into packages that mirror their concerns:
data/ climate, grading, scoring, grid, places, cities,
city_events, store
web/ app, views, homepage, content, schemas
notifications/ notify, digest, push, mailer, discord,
discord_interactions, discord_link
accounts/ models, users, api_accounts, db
core/ metrics, singleton, audit
Intra-project imports are rewritten to the package-qualified form. The
entry scripts (indexnow, warm_cities, migrate, gen_cities, gen_flavor)
and paths.py stay at the backend/ root, and backend/app.py becomes a
shim re-exporting web.app:app so the launch target stays `app:app` —
run.sh, the systemd units, and CI need no change.
Verified: full suite (318) passes, `uvicorn app:app` boots and serves
the home/SEO/static/API surfaces, and every root script imports clean.
Claude-Session: https://claude.ai/code/session_01XXxmNFy9cZ6Gh8Y9thZn62
