Decode the Items Next Action Indicator (TS 102 223 §8.24)

- tag '18' (TS 101 220: "18 only"): one byte per item, §9.4 coding;
  '00' and reserved values mean "no next action" (decoded to None)
- items[] now carry a per-item next_action; a list whose length differs
  from the item count is preserved raw (spec requires X = item count)
- detail view renders "Item 0xNN: text → COMMAND"; the APDU-list summary
  is unchanged — next actions are detail-only, as requested
- tests: 3 real SET UP MENU samples (local sessions 47/53/57) + a
  length-mismatch tolerance case
- v2.1.2; SW cache simtrace-analyser-v57

frontend/index.html

@@ -1284,7 +1284,8 @@ function cmdRows(cmd) {
     if (cmd.icon_id !== undefined) rows.push(['Icon', cmd.icon_id ? 'record #' + cmd.icon_id : 'none']);
     if (cmd.items) {
         for (const it of cmd.items) {
-            rows.push(['Item ' + (it.id !== undefined ? '0x' + hx(it.id, 2) : '?'), it.text]);
+            const next = it.next_action ? ' \u2192 ' + it.next_action : '';
+            rows.push(['Item ' + (it.id !== undefined ? '0x' + hx(it.id, 2) : '?'), it.text + next]);
         }
     }
     if (cmd.duration) rows.push(['Duration', cmd.duration.value + ' ' + cmd.duration.unit]);
@@ -2706,7 +2707,7 @@ function onFilterChange() {
 }
 
 // ──────────────────── Versioning ────────────────────
-const PWA_VERSION = '2.1.1';
+const PWA_VERSION = '2.1.2';
 const MIN_SERVER_VERSION = '1.0.0';
 
 function parseVersion(v) {

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'simtrace-analyser-v56';
+const CACHE = 'simtrace-analyser-v57';
 
 const PRECACHE = [
     'index.html',

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.backends._legacy:_Backend"
 
 [project]
 name = "simtrace-analyser"
-version = "2.1.1"
+version = "2.1.2"
 description = "SIMtrace Analyser — APDU trace analyser for GSMTAP/PCAP captures (bundles the simtrace2-pysniff utility)"
 readme = {file = "README.md", content-type = "text/markdown"}
 license = {text = "GPL-2.0-or-later"}

simtrace_analyser/decode.py

@@ -2620,6 +2620,7 @@ _P_TEXT_STRING = 0x0D
 _P_ITEM = 0x0F
 _P_FILE_LIST = 0x12
 _P_RESPONSE_LEN = 0x11
+_P_NEXT_ACTION = 0x18
 _P_EVENT_LIST = 0x19
 _P_ICON_ID = 0x1E
 _P_AID = 0x2F
@@ -2666,6 +2667,8 @@ def _decode_proactive(body):
     file_list = []
     aid = None
     raw_tlv = []
+    next_actions = None
+    next_actions_hex = None
     text_seen = False
     for tag, _length, value in inner:
         base = tag & 0x7F
@@ -2704,6 +2707,11 @@ def _decode_proactive(body):
             result['text'] = _decode_dcs_text(value)
             result['text_note'] = "text string with non-standard tag '10'"
             text_seen = True
+        elif base == _P_NEXT_ACTION and value:
+            # TS 102 223 §8.24 — one byte per item (§9.4 coding); '00' and
+            # reserved values mean "no next action" and decode to None.
+            next_actions = [CAT_COMMAND_TYPES.get(b) for b in value]
+            next_actions_hex = value.hex().upper()
         elif base == _P_FILE_LIST and value:
             file_list = [value[i:i + 2].hex().upper() for i in range(0, len(value), 2)]
         elif base == _P_AID and value:
@@ -2713,6 +2721,15 @@ def _decode_proactive(body):
         else:
             raw_tlv.append({'tag': f'{base:02X}', 'value': value.hex().upper()})
 
+    if next_actions is not None:
+        if len(next_actions) == len(items):
+            for item, action in zip(items, next_actions):
+                if action:
+                    item['next_action'] = action
+        else:
+            # §8.24 requires X = number of items; keep unexpected lists raw.
+            raw_tlv.append({'tag': '18', 'value': next_actions_hex})
+
     if cmd_type is None:
         return None
     if 0xF0 <= cmd_type <= 0xFE:  # TS 102 223 §9.4 — reserved for proprietary use

simtrace_analyser/version.py

@@ -1,3 +1,3 @@
 """Single source of truth for the SIMtrace Analyser version."""
 
-__version__ = '2.1.1'
+__version__ = '2.1.2'

tests/test_decode.py

@@ -1890,6 +1890,49 @@ class TestRefresh(unittest.TestCase):
                          '0x08 Steering of Roaming for I-WLAN')
 
 
+class TestItemsNextActionIndicator(unittest.TestCase):
+    """Items Next Action Indicator (TS 102 223 §8.24, tag '18') — real
+    SET UP MENU samples from the local trace sessions (47/53/57)."""
+
+    def test_second_item_display_text(self):
+        # session 53: 2 items, item 2 → DISPLAY TEXT ('21'); '00' = no action.
+        r = decode_message(bytes.fromhex(
+            '8012000040D03E810301250082028182850B416C6661204D6F62696C'
+            '658F16808112089DB0C1C2C0BEB9BAB82F53657474696E67738F0A81'
+            '416C66612D494D4549180200219000'))
+        items = r['cmd']['items']
+        self.assertNotIn('next_action', items[0])
+        self.assertEqual(items[1]['next_action'], 'DISPLAY TEXT')
+        # Detail-only: the APDU-list summary stays unchanged.
+        self.assertEqual(r['summary'], 'Alfa Mobile, 2 items')
+
+    def test_second_item_select_item(self):
+        # session 57: 2 items, item 2 → SELECT ITEM ('24').
+        r = decode_message(bytes.fromhex(
+            '8012000044D042810301250082028182050B416C6661204D6F62696C'
+            '658F16808112089DB0C1C2C0BEB9BAB82F53657474696E67738F0E81'
+            '416C66612053494D2074657374180200249000'))
+        self.assertEqual(r['cmd']['items'][1]['next_action'], 'SELECT ITEM')
+
+    def test_last_item_of_nine(self):
+        # session 47: 9 items, only the last has SELECT ITEM ('24').
+        r = decode_message(bytes.fromhex(
+            '80120000E6D081E3810301250082028182051580004D0065006700610046006F006E00500052004F8F100180041C0435043304300424043E043D8F1802800420043004370432043B043504470435043D0438044F8F0C03800421043F043E044004428F100480041D043E0432043E0441044204388F10058004240438043D0430043D0441044B8F1006800421043F044004300432043A04308F100780041E043104490435043D043804358F188080041A0430043B043504390434043E0441043A043E043F8F1A8180041C043E04310438043B044C043D044B043900200049004418090000000000000000249000'))
+        items = r['cmd']['items']
+        self.assertEqual(len(items), 9)
+        self.assertNotIn('next_action', items[0])
+        self.assertEqual(items[-1]['next_action'], 'SELECT ITEM')
+
+    def test_length_mismatch_kept_raw(self):
+        # §8.24 requires X = number of items; a mismatched list stays raw.
+        r = decode_message(bytes.fromhex(
+            '8012000014D0128103012500820281828F03014142180224249000'))
+        items = r['cmd']['items']
+        self.assertEqual(len(items), 1)
+        self.assertNotIn('next_action', items[0])
+        self.assertEqual(r['cmd']['raw_tlv'], [{'tag': '18', 'value': '2424'}])
+
+
 class TestNoReservedLabels(unittest.TestCase):
     # ETSI 'Reserved for GSM/3GPP' values must be resolved via the sibling
     # spec or left unnamed — never surfaced as a 'Reserved ...' label.

tests/test_pcap_import.py

@@ -224,7 +224,7 @@ class TestImportEndpoint(unittest.TestCase):
 class TestVersion(unittest.TestCase):
     def test_package_version(self):
         from simtrace2_pysniff import __version__
-        self.assertEqual(__version__, '2.1.1')
+        self.assertEqual(__version__, '2.1.2')
 
     def test_status_includes_version(self):
         import os