Architecture

flowchart LR
    P[points of all flights] --> E[Enricher: plan per time interval and tile group]
    E --> S[Source.fetch]
    S --> ST[stores: partial reads]
    ST --> RC{range cache}
    RC -- on disk --> ST
    RC -- missing ranges --> N[network]
    S --> K[kernel: vertical, horizontal, time]
    K --> R[values + flags + stats]

• Sources (GridSource for ARCO-ERA5, ArpegeSource, OpenMeteoSource, SourceChain) implement one contract: a time step, the two cube keys bracketing an interval (with a forecast run when relevant), a coverage period, and fetch returning a regional cube (levels × lat × lon).
• Stores read bytes: HttpStore (range requests, retries, per-host caps, redirect learning), FileStore for local mirrors, and format readers on top (zarr-v2 with Blosc block reads, GRIB2 message index, Open-Meteo .om tiles).
• Enricher groups points by interval, splits each time slice along the source's tiling (Source.tiling, see baro.met.tiling), fetches each cube once with bounded look-ahead, and frees it after its last use.
• Kernel interpolates a cube at points (see vertical interpolation).
• Range cache (baro.met.rangecache) keeps every immutable byte range read, below the format readers (Source.use_cache): later requests of any shape only download the missing ranges.