fix(client): address PR #7 review — ephemeral port, input drop docs

Hoshe #1: E2E test now uses random ephemeral port (49152-65535) with
port rotation on bind failure, avoiding conflicts in parallel CI.
Hoshe #2: Documented intentional input drop on encode failure in
SimBridge — re-queuing would retry bad data and server tick has
already advanced.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/scripts/autoloads/sim_bridge.gd

@@ -130,7 +130,10 @@ func _process(delta: float) -> void:
 			while msg.size() > 0:
 				receive_bytes(msg)
 				msg = _bridge.poll_message()
-			# Send: batch-encode and flush outbound buffer as one frame (Vec<PlayerInput>)
+			# Send: batch-encode and flush outbound buffer as one frame (Vec<PlayerInput>).
+			# Inputs are drained before encoding. On encode failure the inputs are
+			# intentionally dropped — re-queuing would retry the same bad data and
+			# the server tick has already advanced, making stale inputs invalid.
 			var outbound := drain_outbound()
 			if outbound.size() > 0:
 				var encoded := Protocol.encode_player_inputs(outbound)
@@ -139,7 +142,7 @@ func _process(delta: float) -> void:
 					if err != OK:
 						push_error("SimBridge: failed to send message: %s" % error_string(err))
 				else:
-					push_error("SimBridge: failed to batch-encode %d inputs" % outbound.size())
+					push_error("SimBridge: failed to batch-encode %d inputs (dropped)" % outbound.size())
 		StreamPeerTCP.STATUS_CONNECTING:
 			pass  # Should not happen in CONNECTED state
 		StreamPeerTCP.STATUS_ERROR:

client/tests/test_e2e_connection.gd

@@ -5,22 +5,45 @@
 class_name TestE2EConnection
 extends GdUnitTestSuite
 
-const TEST_PORT: int = 19876
 const CONNECT_TIMEOUT: float = 3.0
 const RESPONSE_TIMEOUT: float = 5.0
+const MAX_PORT_ATTEMPTS: int = 5
 
 var _server_pid: int = -1
 var _bridge: LocalBridge = null
+var _test_port: int = 0
 
 
 func _server_binary_path() -> String:
-	# Resolve path relative to the Godot project root
 	var project_dir := ProjectSettings.globalize_path("res://")
 	return project_dir.path_join("../server/target/debug/settled-reach-server")
 
 
+## Pick a random high port to avoid conflicts in parallel CI runs.
+## Range 49152-65535 is the dynamic/ephemeral port range (IANA).
+static func _random_test_port() -> int:
+	return 49152 + (randi() % (65535 - 49152 + 1))
+
+
+## Spawn server with port rotation — if the port is in use, the server exits
+## immediately (bind failure). Detect this and retry with a new random port.
+func _spawn_server(server_path: String) -> bool:
+	for attempt in range(MAX_PORT_ATTEMPTS):
+		_test_port = _random_test_port()
+		var addr := "127.0.0.1:%d" % _test_port
+		_server_pid = OS.create_process(server_path, [addr])
+		if _server_pid <= 0:
+			continue
+		# Give server time to bind or fail
+		await get_tree().create_timer(0.15).timeout
+		if OS.is_process_running(_server_pid):
+			return true
+		# Server exited — port likely in use, try another
+		_server_pid = -1
+	return false
+
+
 func after_test() -> void:
-	# Clean up regardless of test outcome
 	if _bridge != null:
 		_bridge.disconnect_from_server()
 		_bridge = null
@@ -37,24 +60,22 @@ func test_send_input_receive_snapshot() -> void:
 		push_warning("E2E test skipped: server binary not found at %s" % server_path)
 		return
 
-	# Spawn server
-	var addr := "127.0.0.1:%d" % TEST_PORT
-	_server_pid = OS.create_process(server_path, [addr])
-	assert_that(_server_pid).is_greater(0)
+	# Spawn server with port rotation (retries if port is in use)
+	var spawned := await _spawn_server(server_path)
+	assert_bool(spawned).is_true()
 
-	# Connect with retries (server needs time to bind port)
+	# Connect with retries (server needs time to accept)
 	_bridge = LocalBridge.new()
 	var connected := false
 	var elapsed := 0.0
 	while elapsed < CONNECT_TIMEOUT:
 		if _bridge.get_status() == StreamPeerTCP.STATUS_NONE:
-			_bridge.connect_to_server("127.0.0.1", TEST_PORT)
+			_bridge.connect_to_server("127.0.0.1", _test_port)
 		_bridge.poll()
 		if _bridge.get_status() == StreamPeerTCP.STATUS_CONNECTED:
 			connected = true
 			break
 		if _bridge.get_status() == StreamPeerTCP.STATUS_ERROR:
-			# Reset and retry
 			_bridge.disconnect_from_server()
 			_bridge.reset()
 		await get_tree().create_timer(0.1).timeout
@@ -91,7 +112,7 @@ func test_send_input_receive_snapshot() -> void:
 	assert_that(snapshot.entities.size()).is_equal(1)
 
 	# Player started at (16, 16, 0), moved north (y-1) to (16, 15, 0)
-	# Render coords: tile center offset → (16.5, 15.5, 0)
+	# Render coords: tile center offset -> (16.5, 15.5, 0)
 	var player: Dictionary = snapshot.entities[0]
 	assert_float(player.x).is_equal_approx(16.5, 0.001)
 	assert_float(player.y).is_equal_approx(15.5, 0.001)