Spec: Label_4A → whole-plugin hatch (matches the pattern of other complex plugins)

The variant+field+formatter-custom shape worked in theory but had no
clean contract for who owns the formatted.items list when the formatter
is custom. Other complex plugins (CBand, ARINC_702, MIAM, etc.) use the
whole-plugin parse-custom + format-description shape; Label_4A follows
suit. Implementation lives in lib/plugins/escape_hatches/Label_4A.ts in
each language repo.

Validates clean: 68 specs OK.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: kevinelliott

spec/labels/4A.yaml

@@ -7,62 +7,14 @@ plugin:
 qualifiers:
   labels: ["4A"]
 parse:
-  - { split: ",", into: fields }
-variants:
-  # Variant 1: 11 fields → timestamp + tail + callsign + airports
-  - name: latest_new_format_11
-    when: { equals: [{ length: $fields }, 11] }
-    fields:
-      - name: timestamp
-        from: $fields[0]
-        decode: { fn: timestamp_hhmmss }
-      - name: tail
-        from: $fields[2]
-        decode: { fn: tail_number, args: { strip_chars: "." } }
-      - name: callsign
-        from: $fields[3]
-        when: { not_equal: ["$fields[3]", ""] }
-        decode: { fn: callsign }
-      - name: departure_icao
-        from: $fields[4]
-        decode: { fn: airport }
-      - name: arrival_icao
-        from: $fields[5]
-        decode: { fn: airport }
-
-  # Variant 2: 6 fields, first one starts with N or S — coords + waypoints.
-  # Complex enough that it gets an escape hatch.
-  - name: latest_new_format_6_position
-    when:
-      all:
-        - { equals: [{ length: $fields }, 6] }
-        - { matches: ["$fields[0]", "^[NS]"] }
-    fields:
-      - name: variant_2_result
-        from: $fields
-        decode:
-          fn: custom
-          custom: label_4a_variant_2_decode
-
-  # Variant 3: 6 fields, not starting with N or S — timestamp + ETA + position
-  - name: latest_new_format_6_status
-    when: { equals: [{ length: $fields }, 6] }
-    fields:
-      - name: timestamp
-        from: $fields[0]
-        decode: { fn: timestamp_hhmmss }
-      - name: eta
-        from: $fields[1]
-        decode: { fn: timestamp_hhmmss }
-      - name: altitude
-        from: $fields[3]
-        decode: { fn: integer }
-      - name: position
-        from: $fields
-        decode:
-          fn: custom
-          custom: label_4a_variant_3_position
-  - default: fail
+  # Whole-plugin hatch. The original Label_4A.ts has three variants selected
+  # by field-count + first-char inspection, with each variant doing inline
+  # ResultFormatter calls (position via substring slicing, route with two
+  # waypoints, temperature, eta, altitude, callsign, tail, airports). The
+  # field-level + format-level decomposition the spec previously attempted
+  # didn't have a clean contract for formatter-owning-raw, so the hatch
+  # form is the right shape here.
+  custom: label_4a_dispatch
 formatted:
   description: "Latest New Format"
   custom: label_4a_format