refactor(radar): typed status fields + soft-fail GenState parser (fixes #129)

[jacaudi]

Summary

Fixes #129. Refactors radar.Data's discrete-value fields onto named string types per go-standards.md §4.1/§4.3, and replaces simplifyGeneratorState with a soft-failing ParseGeneratorState so a degraded NWS payload no longer aborts the 5-minute poll cycle.

Combines Option 5 (typed enums + comparator skip-Unknown) and Option E (symmetric refactor of all status fields) from the design discussion. Option 2's sentinel-error pattern is folded into ParseGeneratorState, and Option 3's token-set parsing lives inside it so the soft-fail is rare in practice.

Changes

Typed enums (§4.1 / §4.3)

Six named string types with const blocks, Stringer methods, and <Type>Unknown sentinels:

Type	Knowns	Sentinel
VCP	VCPR12 / R31 / R35 / R112 / R212 / R215	VCPUnknown
RadarMode	ModeClearAir, ModePrecipitation	ModeUnknown
RadarStatus	StatusOperate / Standby / Test / OfflineOperate	StatusUnknown
OperabilityStatus	OpStatusOnline / Maintenance / Offline / Standby / Coasting	OpStatusUnknown
PowerSource	PowerSourceUtility / Generator	PowerSourceUnknown
GeneratorState	GenStateOn / Off	GenStateUnknown

The underlying string type still accepts arbitrary NWS-supplied values — a surprise input is preserved verbatim for forensic logging rather than squashed into the Unknown bucket. Const blocks document the value space we've actually observed in the wild (per the API survey, though that doc isn't committed in this branch).

Parse<X> constructors

• ParseVCP / ParseRadarStatus / ParseOperabilityStatus / ParsePowerSource — empty input → <Type>Unknown, non-empty passes through verbatim. No error possible.
• ParseGeneratorState — semantic token-set parser. Generator On ∈ pipe-tokens → GenStateOn; only Utility PWR Available → GenStateOff; everything else (including empty) → GenStateUnknown plus an error wrapping ErrUnknownGeneratorState.

FetchData soft-fail (the actual #129 fix)

Mirrors the ErrUnknownVCP shape from #121 (PR #123). When ParseGeneratorState reports ErrUnknownGeneratorState, FetchData logs at WARN with the raw input + station ID and continues with GenState = GenStateUnknown. The previous implementation returned ("", "unknown input") and the caller aborted the entire poll — three of five aborted polls observed in v2.13.1 production logs over 8 days hit that path.

Comparator skip-Unknown

CompareData now skips reporting a flip when the new value equals the field's Unknown sentinel. monitor.processStation only updates the cache when changed=true, so a degraded poll leaves the cache holding the last known-good value; recovery to the same value produces a true no-change. One-sided by design — Unknown→OK on recovery still fires (genuine state-clarification, not noise).

Tests

• TestParseGeneratorState — table-driven. Covers all four canonical raw strings, token-order robustness, and three fallthrough cases (empty, totally novel, ambiguous) with errors.Is(err, ErrUnknownGeneratorState) assertions.
• ExampleParseGeneratorState — §8.3 testable example, output-checked.
• TestCompareData gains three sub-tests for skip-Unknown:
  • skips flip to Unknown on every field — full degraded payload, expect zero notifications
  • flip FROM Unknown is reported (recovery) — first-run-with-degraded-data recovery still fires
  • partial degradation: change on known field only — VCP→Unknown alone with other fields stable produces no notification
• TestGetMode / TestGetVCPInfo updated to use the new typed values.
• MockDataFetcher default response uses the new constants.

go test ./... green across all 9 packages; go vet ./... clean.

Notes

• Data.Name remains string (identifying metadata, not a status).
• simplifyGeneratorState (lowercase, package-private) is removed in favor of ParseGeneratorState. No external callers used the old name.
• monitor.go needed no changes — Mode interpolation goes through %s (Stringer) and VCP equality is type-preserving.

Test plan

• go test ./... — all 9 packages pass
• go vet ./... clean
• Comparator unit tests cover skip-Unknown happy + recovery paths
• ExampleParseGeneratorState round-trips through go test
• Deploy to Talos selfhosted and confirm no spurious notifications on next NWS-degraded-payload event (validation pending real-world recurrence; this is the same failure mode that hit 5 times in 8 days on v2.13.1)

Closes #129. Future symmetric extension targets — alarmSummary from #128, plus controlStatus, superResolutionStatus, and the performance.properties.* encoder-light fields — can layer onto this same shape.

🤖 Generated with Claude Code

[wall-e-one]

🎉 This PR is included in version 2.14.0 🎉

The release is available on:

• v2.14.0
• GitHub release

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