condition_aggregator_nws 0.0.2

NOAA / NWS adapter for the condition_aggregator interface. Maps WinterAlert records from noaa_nws_adapter to the source-neutral Advisory typed event. Pure Dart, no Flutter dependency.

condition_aggregator_nws

NOAA / NWS adapter for the condition_aggregator interface. Wraps noaa_nws_adapter's NoaaNwsClient.fetchActiveWinterAlerts and maps each WinterAlert to the source-neutral Advisory typed event at the adapter boundary.

Phase: explore (publish_to: none in pubspec.yaml). Deploy graduation requires the FDD spike-to-package promotion gate.

Pure Dart. No Flutter dependency. Runtime dependencies: condition_aggregator (interface) + noaa_nws_adapter (raw NWS HTTP+ GeoJSON wrapper).

What this package is

The adapter defines:

• NwsAdvisoryProvider — implementation of AdvisoryProvider for use inside an AdvisoryAggregator. Two constructors: default (owns its own NoaaNwsClient) and withClient (test-injection).
• mapWinterAlertToAdvisory(WinterAlert) → Advisory — direct field mapping, exposed at top level for test invocation without HTTP.

What this package is not

• Not a re-implementation of NWS HTTP / GeoJSON parsing. Those live in noaa_nws_adapter. This package adds typed-event normalization on top.
• Not a multi-region adapter. NWS data is U.S.-region; Japanese-region drivers consume the JMA-class adapter (separate package) inside the same aggregator.
• Not a renderer. The package returns typed Advisory value objects; the integrator HMI surfaces them.

HER-trace (≤4-hop)

NWS api.weather.gov /alerts/active
  → noaa_nws_adapter NoaaNwsClient (HTTP + GeoJSON parse)
  → condition_aggregator_nws NwsAdvisoryProvider (typed mapping)
  → AdvisoryAggregator + integrator HMI surfaces the alert to the
    driver in unexpected snow

4 hops.

Driver-facing loom

When NWS has issued a winter alert for the driver's current point inside the U.S., the integrator HMI surfaces a typed Advisory event with severity / certainty / urgency / area / effective / expires normalized — as the driver's decision substrate, not as raw GeoJSON properties. The publisher's vocabulary is preserved verbatim: Advisory.eventClass carries Winter Storm Warning, Blizzard Warning, Ice Storm Warning, etc. — the words NWS published. areaDescription, headline, and description are passed through without app-class re-summarization. The driver always drives.

Mapping detail

Advisory field	source WinterAlert field
source	constant AdvisorySource.nwsUnitedStates
eventClass	event (verbatim publisher event-class)
severity	severity (CAP-class enum, direct mapping)
certainty	certainty (CAP-class enum, direct mapping)
urgency	urgency (CAP-class enum, direct mapping)
areaDescription	areaDesc (verbatim)
effective	effective (nullable, direct)
expires	expires (nullable, direct)
headline	headline (verbatim)
description	description (verbatim)

WinterAlert carries additional fields (instruction, status, messageType, senderName) that are not surfaced at the source-neutral Advisory boundary today; they are available to integrators that depend directly on noaa_nws_adapter if needed.

Usage

import 'package:condition_aggregator/condition_aggregator.dart';
import 'package:condition_aggregator_nws/condition_aggregator_nws.dart';

final agg = AdvisoryAggregator(providers: <AdvisoryProvider>[
  NwsAdvisoryProvider(
    userAgent: '(myapp.example, [e-mail])',
  ),
]);

await agg.init();

final result = await agg.fetchActiveAdvisoriesAtPoint(
  latitude: 47.9253,
  longitude: -97.0329,
);

for (final a in result.advisories) {
  print('[${a.source.name}] ${a.eventClass}: ${a.headline}');
}

Behaviours worth knowing

• init() is a no-op for this adapter. NWS publishes open public-domain data; no schema-version negotiation, no auth handshake. Configuration (User-Agent) is fully constructor-injected. Calling init() more than once is fine.
• Pass-through for transport / parse exceptions. Underlying noaa_nws_adapter raises NoaaNwsHttpException (transport) and NoaaNwsParseException (GeoJSON shape mismatch). At fan-out time inside AdvisoryAggregator, these are captured into result.providerErrors so the integrator surfaces staleness honestly.
• actualOnly filter is delegated to the underlying client. NoaaNwsClient defaults to actualOnly: true (Test / Exercise / System / Draft entries excluded). Production driver-facing flows inherit that default through this adapter.
• close() releases HTTP resources. Call provider.close() when finished; no-op when withClient(...) was used (caller owns the client).

Dependency posture

• Pure Dart. No Flutter dependency.
• Runtime: condition_aggregator (path), noaa_nws_adapter (path).
• Dev: test, lints.
• Strict-cast / strict-inference / strict-raw-types analyser settings.

License

BSD-3-Clause. See LICENSE (matches the rest of SNGNav).