Add Label 41 CMC Fault Report decoder plugin

[thepacket]

Adds a decoder for airborne maintenance / Central Maintenance Computer fault reports (JetBlue /FB sub-label).

Wire format

/FB 0340/AD MDST/N 39.321,W 74.146,JBU837,MCM03,AIR PACK 1 REGUL FAULT,,,,,,,,,

Surfaces time, maintenance routing address, position, flight ID, CMC message code, plain-English fault description. Nine trailing empty slots (reserved fields) ignored.

npm run build passes.

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Configuration used: Repository UI

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Run ID: 3571575d-dc94-4e66-b016-9a8268163d2f

📥 Commits

Reviewing files that changed from the base of the PR and between 10f9f69 and 1722a89.

📒 Files selected for processing (3)

• lib/MessageDecoder.ts
• lib/plugins/Label_41_Fault.ts
• lib/plugins/official.ts

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[kevinelliott]

Summary

Adds Label_41_Fault for an airborne maintenance / CMC fault report with /FB sub-label (JetBlue variant). Registers in MessageDecoder.ts and lib/plugins/official.ts.

Verdict

The header parse is solid, HHMM range is validated (good — that's better than the sibling PRs), and the position parsing is clean. A couple of items to address before merge.

Must Fix

• No companion Label_41_Fault.test.ts. Every plugin in lib/plugins/ has a Jest test file. Please add one with the example wire format plus negative cases (no /AD token, malformed lat/lon, missing fault text).
• Lossy fall-through. On regex mismatch or invalid HHMM you setDecodeLevel(false) and return without populating remaining.text. Use this.failUnknown(decodeResult, message.text, options) (see Label_15.ts) so the unparsed text is still surfaced.

Should Fix

• Sub-label handling. You manually push a custom {type:'sub_label', code:'SUBLBL'} chip and write raw.sub_label only via the chip metadata. There's an existing ResultFormatter.sublabel(decodeResult, '/FB') helper that sets raw.sublabel and emits a canonical chip. Prefer the helper. Even better: inspect message.sublabel from the parser if it's already populated upstream, rather than re-parsing the prefix from text.
• Qualifier scope. qualifiers() currently returns { labels: ['41'] } with no preamble filter, so this plugin will be tried for every label-41 message. The implementation only handles /FB-prefixed payloads. Consider adding preambles: ['/FB'] (compare with Label_15.ts which uses preambles: ['(2']) so the plugin only fires on matching messages, leaving room for other label-41 variants.
• Flight-number regex. ^[A-Z]{2,3}\d{1,5}[A-Z]?$ matches JBU837 but rejects e.g. tail numbers or longer airline prefixes. If non-matching, you silently skip surfacing it — at minimum log via this.debug(options, ...) so the dropped value is visible during debugging.

Nits

• Message Type chip duplicates formatted.description. Same applies to the SUBLBL chip if ResultFormatter.sublabel is adopted.
• decodeResult.raw.report_time stores "HH:MM" while raw.message_timestamp (from ResultFormatter.timestamp) stores seconds-since-midnight — consumers now have two slightly different "report time" representations on the same result. Drop the string version unless there's a downstream that needs it.
• Lat/lon parse uses \d+(?:\.\d+)? — fine for the example. No range check on lat (≤90) / lon (≤180); worth a one-liner.
• Several (parts[N] || '').trim() calls — parts is already trimmed via .map((s) => s.trim()), the second .trim() is redundant.

Tests

Missing — please add Label_41_Fault.test.ts.

Notes

• Registration: confirmed in lib/MessageDecoder.ts and lib/plugins/official.ts. Good.

Thanks @thepacket!