route_condition_forecast 0.2.0

Per-segment weather and hazard forecasting along a planned route. Projects driving_weather + fleet_hazard onto route segments. Pure Dart.

Changelog

0.2.0

Safety defect in 0.1.5 and earlier — please read

Up to and including 0.1.5, a route whose weather was never measured reported itself as CLEAR.

RouteForecast.hasAnyHazard and SegmentConditionForecast.isHazardous were bool. A bool cannot say "I do not know", so it resolved absence to false — and for a hazard question, false is the "clear road" branch. Concretely:

• driving_weather up to 0.4.4 could hand us a WeatherCondition full of fabricated values (+5.0 °C, visibility 10000 m, iceRisk: false) whenever a feed came back empty;
• every segment carrying it answered isHazardous == false;
• hasAnyHazard therefore answered false — the route is clear;
• and adaptive_reroute turned that into RerouteDecision.clear() with confidence: 1.0.

A route nobody had looked at was presented to the driver as verified safe, with total certainty. An empty forecast (zero segments) also answered hasAnyHazard == false, and minimumConfidence returned 1.0 — perfect confidence, derived from nothing.

pub.dev versions are immutable. This note is the recall.

Breaking: hazard verdicts are tri-state

• SegmentConditionForecast.isHazardous (bool) → hazard (SafetyVerdict).
• SegmentConditionForecast.hasWeatherHazard (bool) → weatherHazard (SafetyVerdict).
• RouteForecast.hasAnyHazard (bool) → hazard (SafetyVerdict).
• RouteForecast.hasWeatherHazard (bool) → weatherHazard (SafetyVerdict).
• RouteForecast.minimumConfidence (double) → double? (null for an empty forecast; it used to return a fabricated 1.0).

if (forecast.hasAnyHazard) no longer compiles. You must now handle SafetyVerdict.unknown explicitly, and Dart's exhaustive switch will refuse code that does not. Do not write == SafetyVerdict.hazardous ? warn() : allClear() — that puts unknown back in the all-clear branch, which is the defect.

Resolution order (the contract's asymmetry):

• ANY hazardous segment ⇒ hazardous — positive evidence fires even when the rest of the route is unknown;
• else incomplete coverage or ANY unknown segment ⇒ unknown — a route is only as assessed as its least-assessed segment;
• else notHazardous.

An empty forecast is unknown, not clear. Forecasting nothing is not the same as forecasting good news.

New: the forecast admits where it could not look

• SegmentConditionForecast.isUnassessed
• RouteForecast.firstUnassessedSegment, unassessedSegmentCount
• RouteForecast.unlocatableManeuverCount, coversWholeRoute

routing_engine 0.6.0 makes RouteManeuver.position nullable (null = the engine returned no usable coordinate; up to 0.5.0 it silently substituted const LatLng(0, 0) — Null Island, a real place in the Gulf of Guinea). RouteSegmenter.byManeuver now skips a maneuver with no position rather than anchoring a segment to a fabricated coordinate — which would have queried the weather in the Atlantic and attributed the answer to a road in Akita.

Skipping is itself an absence, so it is reported, not hidden: a route with any unlocatable maneuver has coversWholeRoute == false and its hazard is unknown even if every segment we could forecast came back benign. A silently short forecast reads exactly like a clear one.

Migration

0.1.5	0.2.0	On unknown
forecast.hasAnyHazard (bool)	forecast.hazard (SafetyVerdict)	Tell the driver the route could not be assessed. Do not proceed as if clear.
segment.isHazardous (bool)	segment.hazard (SafetyVerdict)	—
segment.hasWeatherHazard	segment.weatherHazard	—
forecast.minimumConfidence (double)	double?	null = no segments; there is no confidence to report.

firstHazardSegment == null does not mean the route is clear — it means no segment carried positive evidence of a hazard. Check hazard and firstUnassessedSegment before saying anything reassuring.

Also

• Requires driving_weather: ^0.5.0 and routing_engine: >=0.6.0 <0.7.0.
• One pre-existing test certified the defect and has been inverted: it asserted that an empty forecast reports hasAnyHazard == false. It now asserts hazard == SafetyVerdict.unknown.
• Behaviour on fully measured, fully located routes is unchanged.

0.1.5

• Widen the routing_engine constraint to >=0.4.0 <0.6.0 so consumers can take routing_engine 0.5.0 (language-honoring turn-by-turn narration) alongside route_condition_forecast — this pin was the last CATALOG link blocking the Android reach vehicle (sngnav-app) from resolving the Japanese narration. Reach itself is still OPEN at this publish: the app must additionally widen its own routing_engine pin and take voice_guidance ^0.7.x, and the narration must be verified ON DEVICE before any reach claim (publish ≠ reach). No library code change (lib/ is byte-identical to 0.1.4). Consumers who prefer English instructions with default requests can pin routing_engine: ^0.4.0 or pass language: 'en' (see routing_engine 0.5.0's changelog).

0.1.4

• deps: require fleet_hazard: ^0.5.0 (the anonymized aggregate — HazardZone no longer retains a re-identifiable per-vehicle trail). No API change here; this package reads only zone center/severity/vehicleCount/confidence, all preserved. Tests updated to the ZoneObservation element type.

0.1.3

• Republish from the embedded-target Dart 3.10.1 SDK (Flutter 3.38.3) to correct a stale ^3.11.0 SDK floor in the previously-published artifact. No source or behavior change; the source already declared sdk: ^3.10.0. Restores pub get for embedded/automotive Dart consumers on Dart 3.10.x.

0.1.2 — 2026-05-10 — Pana score recovery (Theme α P3)

• Trim pubspec description to within the pana 60–180 character target.
• Add minimal example/main.dart for pana documentation scoring.
• Apply dart format to clear any formatter findings.
• No SDK source changes; metadata + format pass only.

0.1.1 — 2026-05-10 — Refresh cascade-stale dependency constraints

• driving_weather: ^0.3.0 → ^0.4.0 (consumer-side refresh after driving_weather 0.4.0 release earlier the same day).
• fleet_hazard: ^0.3.0 → ^0.4.0.
• routing_engine: ^0.3.0 → ^0.4.0.
• No source changes; pubspec dep-constraint refresh only.

0.1.0 — 2026-04-27

Initial release.

Per-segment weather and hazard forecasting along a planned route. Projects current driving_weather conditions and fleet_hazard zones onto route segments with time-of-arrival weighting.

Exports:

• RouteForecast, RouteSegment, SegmentConditionForecast models
• ForecastProvider interface + CurrentConditionsForecastProvider (uses current weather as best estimate when no time-series source is available)
• RouteConditionForecaster service
• RouteSegmenter service

Pure Dart. No Flutter dependency.