native_duct.rs is the Rust side of HrrrNativeClient.fetch_native_duct_grid:
fetch native-level HRRR idx → select duct byte ranges (TMP/SPFH/HGT/PRES
× 50 hybrid levels = 200 messages, ~300 MB subset) → wgrib2 decode via
the existing decoder::extract_grid plumbing → per-cell build_native_profile
→ duct::analyze → HashMap<(lat, lon), DuctMetrics>.
build_native_profile keeps the Elixir semantics intact: drop cells that
don't reach 3 levels, sort by ascending height, tolerate missing SPFH/PRES
as zero (the duct math handles zeros gracefully). merge_duct_grid gives
the pipeline.rs caller a drop-in replacement for Elixir's apply_duct_grid.
claim_next_analysis is the analysis-lane companion to claim_next: selects
kind='analysis' rows only, same SKIP LOCKED + newest-first ordering. Kept
on a separate claim function so the forecast lane can keep running
unaffected during cutover; the analysis pipeline wiring lands next.
9 pure unit tests cover message generation, URL builder, profile-sort,
min-level filter, and merge-into-base behaviour. Network-live golden
against a real native GRIB2 deferred to the cutover commit.
Graham McIntire
22f5828b7e