Add Label B2 Oceanic Clearance Acknowledgement decoder plugin

[thepacket]

Adds a decoder for FANS Oceanic Clearance Acknowledgement (OCRA / CLA) downlinks.

Wire format

/PIKCLYA.OC1/CLA 1911 260420 EGGX CLRNCE 296 AFR012 CLRD TO KJFK VIA
DINIM RANDOM ROUTE DINIM 5130N020W 5230N030W 5130N040W 4930N050W IBERG
FM DINIM/2039 MNTN F400 M085 END OF MESSAGE 694F

Surfaces ground station, UTC time, date (YYMMDD → ISO), oceanic FIR, clearance number, callsign, destination, route type (random/NAT track), waypoints, oceanic entry fix + entry time, cleared flight level, cleared Mach, trailing CRC.

npm run build passes.

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📥 Commits

Reviewing files that changed from the base of the PR and between 10f9f69 and 7607215.

📒 Files selected for processing (3)

• lib/MessageDecoder.ts
• lib/plugins/Label_B2_OCRA.ts
• lib/plugins/official.ts

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[kevinelliott]

Summary

Adds Label_B2_OCRA for FANS Oceanic Clearance Acknowledgement (CLA) downlinks. Parses station envelope, time, date, oceanic FIR, clearance number, callsign, destination, route type (random / NAT track), waypoints, oceanic entry fix and entry time, cleared flight level, cleared Mach, and trailing CRC. Registered in both lib/MessageDecoder.ts and lib/plugins/official.ts. Build passes per the description.

Verdict

Needs changes before merge. The shape of the parser is correct and the field set is comprehensive, but there's a Mach decoding bug, two duplicate-row antipatterns, and the date-format choice deserves explicit justification.

Must Fix

• Mach decoding bug. Line 105-106:

  const machM = routeClean.match(/\bM(\d{3})\b/);
  if (machM) machNumber = `0.${machM[1]}`.replace('0.0', '0.');
  

  This works for M085 (→ 0.085 → replace gives 0.85) but breaks for any Mach where the second digit isn't zero — e.g. M082 becomes 0.082 and the replace finds no match, leaving the wrong value. Mach numbers in oceanic clearances are typically M078–M092. The intended decoding is "drop the leading M and divide by 100" — implement that directly:

  if (machM) machNumber = (Number(machM[1]) / 100).toFixed(2);

• Duplicate Time row (project antipattern). Lines 130-133 call ResultFormatter.timestamp(...) which already pushes a {type:'time', code:'TIMESTAMP'} item. Then lines 162-168 explicitly push another {type:'time', code:'TIME'} row with the same value. Pick one. Same issue is flagged in PR #412.
• Duplicate Callsign row (project antipattern). Line 137 calls ResultFormatter.flightNumber(decodeResult, callsign) (adds a "Flight Number" item) and lines 188-192 push a separate {code:'CALLSIGN', label:'Callsign'} row with the same string. For a callsign rather than a flight number, prefer ResultFormatter.callsign(...) (lib/utils/result_formatter.ts line 93) and drop the manual push.
• No tests. Please add Label_B2_OCRA.test.ts with at least the wire-format example, a NAT-track variant (so routeType resolves to NAT Track <letter>), a missing-CRC body, and a body where the optional VIA group is absent. Use lib/plugins/Label_15.test.ts as a template.

Should Fix

• Date format claim needs justification. Lines 21-23 declare YYMMDD and explicitly note "an earlier analyst report read this as DDMMYY; that interpretation is inconsistent with the real message date — corrected here." With only a single sample message, this is fragile. Please:
  • cite the source (ARINC 622 / FANS-1/A spec section, an additional message sample, or a libacars reference) in the docstring,
  • or accept both formats, validate the resulting date against a sanity window (year between e.g. 2000 and current year + 1), and pick whichever yields a valid date.
    Without one of these, the next operator that emits DDMMYY will produce wrong ISO dates silently.
• time validation only checks HH/MM but the value passed to convertHHMMSSToTod is time + '00'. Fine because time is \d{4} per the regex, but the comment "Time field" in the docstring should call out that seconds are forced to zero (not parsed from the wire).
• Destination regex [A-Z]{3,4}. Three-letter destinations risk colliding with route tokens. The wire format always uses 4-letter ICAO. Tighten to [A-Z]{4}, or document why the 3-letter form is needed.
• Waypoint coordinate regex. Line 121: /^\d{4}N\d{3}W$/ and /^\d{4}N\d{3}E$/ — these reject southern-hemisphere waypoints (5130S020W). Add S to the latitude-hemisphere alternation and document that lat is (N|S) and lon is (E|W). Consider a single regex ^\d{4}[NS]\d{3,5}[EW]$ (longitudes can also be 5 digits at high latitudes if the format includes minutes).
• channel raw key. The envelope splits station from channel on ., e.g. PIKCLYA.OC1 → station=PIKCLYA, channel=OC1. "Channel" isn't really the right word — OC1 is more like a service qualifier (Oceanic Clearance, instance 1). Suggest service_qualifier or imi, matching the FANS 1/A vocabulary used in PR #411.
• route_type for NAT track. "NAT Track A" is a friendly label, but downstream consumers will more easily key off a stable code like NAT_A or a structured {type:'nat', track:'A'} object. Same logic for 'Random Route' → 'random' raw, friendly value in formatted.

Nits

• report_date: rename to clearance_date to match the surrounding domain vocabulary.
• entry_time raw is HH:MM — better to store as a numeric tod (DateTimeUtils.convertHHMMSSToTod(entryTime + '00')) for consistency with message_timestamp.
• cleared_flight_level value is 'F400' — most downstream consumers want a number (400). The formatted-display already strips the F.
• The "Ground Station" formatted row uses the joined value ${station}.${channel} — but the raw fields store them separately. Worth surfacing the join only if you keep a separate parsed channel field.

Tests

Missing entirely. Beyond the four scenarios under Must Fix, please add: invalid HH (e.g. 2911), invalid date (260435), Mach values across the range (M078, M085, M092).

Notes

• Registration: confirmed in both lib/MessageDecoder.ts (line 81) and lib/plugins/official.ts (line 67) at the PR HEAD.
• FANS 1/A consistency: like PRs #409, #411, #412, this plugin introduces its own envelope-parse + CRC-strip + tail/callsign-extract logic. Please align raw-key naming with those three (crc here matches PR #412, but PR #411 uses crc and PR #409 uses crc_hex — pick one).

Thanks @thepacket!