A shared units module in nav.js holds the active unit (persisted), converts
Fahrenheit API values for display, and notifies pages to repaint on a switch.
A segmented °F/°C control is injected into the top-right of every header
(left of the view tabs); Weekly, Day and Calendar convert every temperature —
cards, dense timeline, trend chart axis/labels, tooltips and the PNG export —
while wind, humidity and precip stay as-is. Compare keeps its Fahrenheit
comfort slider, so the toggle is hidden there.
* Compress API responses and revalidate static assets instead of re-downloading
- Add GZipMiddleware (min 1 KB): the 2-year calendar JSON shrinks ~6-8x.
- Serve pages/assets with Cache-Control: no-cache instead of no-store, so
browsers revalidate via the ETag/Last-Modified that FileResponse and
StaticFiles already emit. Unchanged assets now cost an empty 304 rather
than a full transfer on every page navigation, while deploys still show
up immediately.
* Persist derived responses in SQLite so grading is computed once per cell, not per request
New data/thermograph.sqlite (WAL) holds what's derived from the raw parquet
records — finished grade/calendar/day/forecast payloads and reverse-geocode
labels — so the expensive work (notably the 2-year calendar grade_range, ~270ms)
becomes a ~5ms database read that survives restarts and is shared across views.
Raw parquet stays the source of truth; the store is a pure accelerator (every
reader falls back to recomputing on a miss, and deleting the db is a safe reset).
Freshness is token-driven, not clock-driven: each cached payload is validated by
a token encoding what it was computed from (payload schema version, the archive
record's end date, the recent-fetch stamp). The existing freshness drivers are
untouched — get_history still tops up the tail hourly and get_recent_forecast
still refetches hourly — and tokens are derived from what they return, so cached
payloads expire exactly when their inputs change. The same tokens double as weak
ETags: If-None-Match answers with an empty 304 without touching the payload.
- backend/store.py: derived-payload + revgeo tables, thread-local WAL conns,
every helper fail-soft.
- app.py: endpoints split into pure payload builders + HTTP/caching shells; the
in-memory 10-minute _CAL_CACHE is retired (superseded by the persistent store).
- climate.py: revgeo persisted through the store; recent_stamp() and
load_cached_history() (no-network read) helpers.
- backend/migrate.py + make migrate: idempotent, resumable backfill of the store
from existing parquet caches (default calendar span + latest-day detail +
revgeo, ≤1 throttled Nominatim call per unlabeled cell). Never fetches weather.
- grid.from_id(): rebuild a cell from its cache filename (migrate tooling).
* Add /api/v2/cell: one bundle carrying every view's payload
GET /api/v2/cell?lat&lon returns the grade, forecast, calendar (last 24 months)
and day (today) payloads in one response, each the exact payload its per-view
endpoint returns — built by the same builders and cached under the same
derived-store keys/tokens — paired with the etag that endpoint would emit. The
frontend can warm all views with a single request, seed its per-view cache from
the slices, and later revalidate each view individually with If-None-Match. The
bundle's own etag combines the slices', so an unchanged bundle is an empty 304.
prefetch=1 is a warm-only mode for neighbor-cell prefetching with a hard
guarantee: it never spends weather-API quota. A cell with no cached archive
answers 204, and only the history-derived slices (calendar + latest-day detail)
are built. At most one Nominatim lookup for a never-labeled cell.
* Frontend: IndexedDB response cache with stale-while-revalidate + bundle prefetch
The per-URL response cache moves from localStorage/sessionStorage (~5 MB quota,
which multi-year calendar payloads regularly blew through) to IndexedDB, with an
in-memory map in front. Entries carry the server's ETag, so anything stale
revalidates conditionally — unchanged data costs an empty 304 and a re-stamp,
never a re-transfer. On network failure the stale copy is served over an error.
getJSON gains an optional onUpdate callback opting into stale-while-revalidate:
the three views (weekly, day, calendar) now render a cached copy immediately —
spinners are delayed 150ms so warm loads never flash-blank — and repaint only if
background revalidation finds changed data. New data shows up the moment it
exists instead of waiting out a TTL.
Cross-view prefetch collapses from one request per view to a single /api/v2/cell
bundle, whose slices (exact per-view payloads + their etags) are seeded under the
URLs each view actually requests; the bundle call itself is conditional via a
remembered etag. Afterwards the 8 surrounding grid cells are warmed server-side
with prefetch=1 (never spends weather-API quota; staggered ≥1.1s for the one
possible Nominatim lookup each), so tapping nearby lands on already-graded data.
Legacy tg:* storage entries are cleared once; cache entries untouched for two
weeks are pruned on page load.
Two related client-cache improvements in nav.js:
- Day-of-fetch freshness: every cached API response is now tagged with
the viewer's local calendar day, and a cache hit requires both the TTL
AND a same-day tag. A cache stored yesterday is refetched today, so a
new day's data (and the calendar's "days shown") can't stay hidden
behind an otherwise-fresh cache across a midnight rollover.
- Cross-view prefetch now covers the Day page (api/v2/day), which it
previously never warmed, and skips any view that already has a fresh
same-day cache — so it only fetches the pages actually missing one.
Claude-Session: https://claude.ai/code/session_019VP23wKmjS2ozk1g5a9g1Z
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
