Comprehensive APRS parsing overhaul — near-parity with perl-aprs-fap (FAP.pm)

[hemna]

Summary

Comprehensive APRS protocol parsing overhaul achieving near-parity with perl-aprs-fap (FAP.pm), the gold standard parser used by aprs.fi. All 397 tests pass.

FAP.pm Gap Analysis — 14 Features Implemented

A line-by-line gap analysis against perl-aprs-fap identified 14 missing features. All are now implemented with unit tests.

#	Gap	Module	Description
1	KISS ↔ TNC-2	aprslib/kiss.py	Binary AX.25 KISS frame to/from TNC-2 text format conversion
2	Duplicate Detection	aprslib/dedup.py	dedup_key field + DuplicateFilter class (marks, never drops)
3	DX Spot Parsing	aprslib/parsing/dx.py	Parse "DX de CALL: freq call info" → structured fields
4	Symbol from Destination	aprslib/parsing/dstsymbol.py	GPSxyz/SPCxyz destination → symbol table/code + overlay
5	Object Construction	aprslib/packets/object.py	ObjectReport and ItemReport packet builders
6	NMEA Checksum	aprslib/parsing/misc.py	XOR validation, sets nmea_checksum_ok flag
7	Messaging Flag	(already existed)	messagecapable field on = and @ DTI
8	Distance/Direction	aprslib/geo.py	Great circle distance (km) and bearing (degrees) via Haversine
9	Position Resolution	aprslib/geo.py	Meters of uncertainty from position ambiguity spaces
10	Peet Bros !! Frame	aprslib/parsing/peetbros.py	!! logging frame with indoor temp/humidity
11	$ULTW Full 13 Fields	aprslib/parsing/peetbros.py	Extended weather: humidity, indoor temp, rain override
12	GPGLL Extraction	aprslib/parsing/misc.py	Full lat/lon/time/status parse for GLL sentences
13	Broken Mic-E Fixup	aprslib/parsing/mice.py	accept_broken option repairs corrupted IGate packets
14	Comment Cleanup + WX ID	common.py + weather.py	Strip control chars, extract weather software ID

Additional Parsers (earlier commits on this branch)

Feature	DTI/Type	File
Query packets	?	aprslib/parsing/query.py
NWS weather alerts	Object comment	aprslib/parsing/nws.py
Area objects (circle/line/ellipse/triangle/rect)	\l symbol	aprslib/parsing/common.py
Signpost objects	\m symbol	aprslib/parsing/common.py
DF Reports	DFSshgd	aprslib/parsing/common.py
Frequency/Tone/Offset	Position comment	APRS 1.2 freq spec extraction
Mic-E device type	Suffix detection	Kenwood, Yaesu, Anytone, Byonics
Item-in-Message	Message body	Embedded item detection
Telemetry config	PARM/UNIT/EQNS/BITS	Message-based telemetry config
Comment telemetry	Inline	Sequence/analog/digital in comments
Station capabilities	<	Station capability parsing
Third-party	}	Recursive unwrap of relayed packets
Maidenhead locator	[	Grid square beacon parsing

Design Principles

• parse() never drops packets — enriches with new fields, apps decide what to act on
• Backward compatible — no existing field names changed, only additions
• Stateless core — stateful helpers (DuplicateFilter, TelemetryStore) are opt-in

Test Coverage

• 397 tests pass
• Every new feature has dedicated unit tests
• Zero regressions on existing test suite