Adopt the released reader: all four levels forward

docs/snippets/js/weather/reading/absent_values.ts

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+// Preamble, not shown on the page: a weather file the page's earlier step read.
+import { monthlyMeans, type WeatherFile } from '@idfkit/weather';
+declare const epw: WeatherFile;
+
+// --8<-- [start:example]
+// A measurement the file says was not taken is absent, not the number the format
+// reserves for it. Absence is NaN: no weather file can express one, so it is not
+// a value the column could otherwise have held.
+const albedo = epw.hours.albedo;
+Number.isNaN(albedo[0]); // true where the file wrote its missing value
+
+// How many hours of a column are present is carried rather than recomputed.
+epw.hours.presentCount.albedo;
+
+// A monthly mean excludes the absent hours from the sum AND from the divisor, so
+// it is the mean of the values that exist. The count says how many that was.
+const january = monthlyMeans(epw, 'dryBulbTemperature')[0]!;
+january.mean; // NaN when the month held no measurement at all
+january.count; // and 0 beside it, which says why
+// --8<-- [end:example]
+
+export { albedo, january };

docs/snippets/js/weather/reading/read_an_epw.ts

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+// Preamble, not shown on the page: the EPW text the page's earlier step retrieved.
+import { parseEpw } from '@idfkit/weather';
+declare const epwText: string;
+
+// --8<-- [start:example]
+// Reading takes the text you already hold. No network, no filesystem, nothing
+// asynchronous, so this runs in a browser tab as readily as in Node.
+const epw = parseEpw(epwText);
+
+epw.location.city; // 'Chicago Ohare Intl Ap'
+epw.hours.rowCount; // 8760, taken from the file's declared data period
+
+// Every numeric field is a named column, packed and the same length.
+const temperature = epw.hours.dryBulbTemperature; // Float64Array, degrees C
+temperature[0]; // the first hour of 1 January
+
+// The hour column runs 1 to 24, and hour 24 is the last hour of its OWN day
+// rather than hour 0 of the next.
+epw.hours.hour[23]; // 24
+epw.hours.day[23]; // still 1
+// --8<-- [end:example]
+
+export { epw, temperature };

docs/snippets/js/weather/station-search/filter_by_climate_zone.ts

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+// Preamble, not shown on the page: the index the page's earlier steps produced.
+import type { StationIndex } from '@idfkit/weather';
+declare const index: StationIndex;
+
+// --8<-- [start:example]
+// Ask for a zone by its code. The code is parsed out of the label rather than
+// read off the front of it, which matters: 2,162 of the 69,638 bundled records
+// are labelled '7A - ASHRAE Climate Zone could not be determined' or '8A - ...',
+// and neither 7A nor 8A is an ASHRAE zone, since zones 7 and 8 carry no suffix.
+const zone4a = index.filter({ climateZone: '4A' });
+
+// Combine with the other keys, which all narrow together.
+const seattleArea = index.filter({ climateZone: '4C', country: 'USA', state: 'WA' });
+
+// The stations whose zone upstream could not determine are reachable, and only
+// this way: no climateZone value returns them. Asking for them is a separate
+// question because the zone key's domain is already every real code, so a
+// reserved string could not be told apart from one.
+const undetermined = index.filter({ climateZoneDetermined: false });
+// --8<-- [end:example]
+
+export { zone4a, seattleArea, undetermined };