wire stream: compare a click's state id as its lag behind the server; hotbar_swap swings at the sky

A run's state ids count every change its server made since the login, so a click numbered 53 in one
run and 55 in the other were both up to date. hotbar_swap now also taps a number key with a swing at
nothing, where vanilla sends the slot only on the next tick.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

tests/test_wire_stream.py

@@ -72,6 +72,21 @@ class WireStreamTest(unittest.TestCase):
         self.assertEqual(wire_stream.decode('player_action', varint(0) + as_long(29999999, 2047, -30000000)
                                             + b'\1' + varint(3))['pos'], [29999999, 2047, -30000000])
 
+    def test_a_click_s_state_id_compares_as_how_far_it_lags_the_server(self):
+        def set_slot(state):
+            return {'conn': 1, 'dir': 's2c', 'state': 'play', 'name': 'container_set_slot',
+                    'data': (varint(0) + varint(state) + b'\0\x24\0').hex()}
+
+        def click(state):
+            return c2s('container_click', varint(0) + varint(state) + b'\0\x24\0' + varint(0) + b'\0\0')
+        # Two runs whose servers counted differently: both clicks are up to date, the third is one behind.
+        a = wire_stream.scenarios([LOGIN, set_slot(53), mark(), click(53), TICK_END])
+        b = wire_stream.scenarios([LOGIN, set_slot(55), mark(), click(55), TICK_END, set_slot(56), click(55),
+                                   TICK_END])
+        self.assertEqual(a[0][0]['packets'], b[0][0]['packets'])
+        self.assertEqual(a[0][0]['packets'][0][1]['stale'], 0)
+        self.assertEqual(b[0][1]['packets'][0][1]['stale'], 1)
+
     def test_compare_reports_the_first_field_that_differs(self):
         tick = lambda y: {'packets': [('move_player_pos', {'x': 0.5, 'y': y})], 'frame': [], 'misplaced': []}  # noqa
         diffs = wire_stream.compare([tick(-60.0)], [tick(-60.0000001)], 0)

tools/test_wire_stream_parity.py

@@ -151,9 +151,12 @@ SCENARIOS = {
         setup=[TARGET.format(x=0.5, y=FLOOR + 1, z=3.0)] +
               [f'item replace entity {PLAYER} hotbar.{i} with minecraft:{item}' for i, item in
                enumerate(['diamond_sword', 'stone_axe', 'golden_apple', 'stone', 'bow'])],
-        ticks=50, steps=merge({0: ['look 0 20']}, {t: [f'key {t % 5 + 1} tap'] for t in range(5, 15)},
+        # 52-54: a swing at the sky with a new slot sends no slot before its Punch (no ensureHasSentCarriedItem
+        # on a miss); the next tick's MultiPlayerGameMode.tick does.
+        ticks=60, steps=merge({0: ['look 0 20']}, {t: [f'key {t % 5 + 1} tap'] for t in range(5, 15)},
                               {16: ['key 2 tap', 'mouse left click'], 20: ['key 1 tap'], 21: ['key 3 tap'],
-                               30: ['key 5 tap', 'mouse left click'], 35: ['key q tap'], 40: ['key f tap']})),
+                               30: ['key 5 tap', 'mouse left click'], 35: ['key q tap'], 40: ['key f tap'],
+                               52: ['look 0 -80'], 54: ['key 3 tap', 'mouse left click']})),
     'dig_teleport': dict(
         setup=[f'setblock 0 {FLOOR + 1} 2 minecraft:stone'],
         ticks=60, steps={0: ['look 0 45'], 3: ['mouse left down'], 15: ['command tp @s ~ ~ ~'],

tools/wire_stream.py

@@ -130,13 +130,26 @@ def self_id(entries):
 
 def scenarios(entries):
     """One list of ticks for each /wire-mark in the play stream, in order (the ticks after a mark run to the
-    next mark); a tick is {'packets': [(name, fields)], 'frame': [(name, fields)], 'misplaced': [name]}."""
+    next mark); a tick is {'packets': [(name, fields)], 'frame': [(name, fields)], 'misplaced': [name]}.
+
+    A click's state id becomes `stale`: how far it is behind the last one the server sent for that container
+    (0 = up to date). The ids themselves count every change the server made since the login, so two runs
+    whose earlier scenarios differed number the same click differently."""
     me = self_id(entries)
-    c2s = [e for e in entries if e.get('dir') == 'c2s' and e.get('state') == 'play' and 'name' in e]
-    runs, current = [], None
-    for e in c2s:
+    play = [e for e in entries if e.get('state') == 'play' and 'name' in e and e.get('dir') in ('c2s', 's2c')]
+    runs, current, server_state = [], None, {}
+    for e in play:
         name = e['name']
+        if e['dir'] == 's2c':
+            if name in ('container_set_content', 'container_set_slot'):
+                r = Reader(bytes.fromhex(e.get('data', '')))
+                container = r.varint()
+                server_state[container] = r.varint()
+            continue
         fields = decode(name, bytes.fromhex(e.get('data', '')))
+        if name == 'container_click':
+            last = server_state.get(fields['container'], fields['state'])
+            fields = {'container': fields['container'], 'stale': last - fields.pop('state'), **fields}
         if name == 'chat_command' and fields.get('command') == 'wire-mark':
             current = [new_tick()]
             runs.append(current)