Bugfixes, renames, create custom TextEditor, logic simplifications

Implementation/Peered/NoteEditor/ManageMembersScreen.swift

@@ -6,7 +6,7 @@
 //
 import SwiftUI
 
-struct ManageMembersView: View {
+struct ManageMembersScreen: View {
 	@Bindable var noteAdvertiser: NoteEditingSessionServer
 	let noteTitle: String
 	@Binding var noteContent: String

Implementation/Peered/NoteEditor/NoteEditingSessionServer.swift

@@ -16,9 +16,7 @@ struct Peer: Identifiable {
 		case invitationPending
 	}
 	
-	var id: String {
-		mcPeer.displayName
-	}
+	var id: String { mcPeer.displayName }
 	let mcPeer: MCPeerID
 	var state: ConnectionState
 }
@@ -47,6 +45,7 @@ final class NoteEditingSessionServer: NSObject {
 	
 	func stopServer() {
 		browser.stopBrowsingForPeers()
+		session.disconnect()
 	}
 	
 	func invite(peer: Peer, to note: NoteInvitation.NoteContent) {

Implementation/Peered/NoteEditor/NoteTextEditor.swift

@@ -0,0 +1,61 @@
+import SwiftUI
+
+struct NoteTextEditor: View {
+    @Binding var text: String
+    let remoteText: String?
+    @State private var selection: TextSelection? = nil
+
+    var body: some View {
+        TextEditor(text: $text, selection: $selection)
+            .onChange(of: remoteText) { oldValue, newValue in
+                guard let newValue, newValue != text else { return }
+
+                let previousRemote = oldValue ?? text
+
+                // Where the remote edit begins
+                let changeStart = commonPrefixUTF16Length(previousRemote, newValue)
+
+                // How many UTF-16 units were inserted (positive) or removed (negative)
+                let delta = newValue.utf16.count - previousRemote.utf16.count
+
+                // Apply remote text first
+                text = newValue
+
+                // Get current cursor offset
+                guard
+                    let selection,
+                    case .selection(let range) = selection.indices,
+                    let cursorPos = range.lowerBound.samePosition(in: text.utf16)
+                else { return }
+
+                let cursorUTF16 = text.utf16.distance(
+                    from: text.utf16.startIndex,
+                    to: cursorPos
+                )
+
+                // Only shift if the change happened strictly before the cursor
+                guard changeStart < cursorUTF16 else { return }
+
+                let newCursorUTF16 = max(0, min(cursorUTF16 + delta, newValue.utf16.count))
+                let newUTF16 = newValue.utf16
+                let newUTF16Index = newUTF16.index(newUTF16.startIndex, offsetBy: newCursorUTF16)
+                guard let newIndex = newUTF16Index.samePosition(in: newValue) else { return }
+
+                self.selection = TextSelection(range: newIndex..<newIndex)
+            }
+    }
+
+    private func commonPrefixUTF16Length(_ a: String, _ b: String) -> Int {
+        var count = 0
+        let aUTF16 = a.utf16
+        let bUTF16 = b.utf16
+        let minLen = min(aUTF16.count, bUTF16.count)
+        while count < minLen {
+            let aIdx = aUTF16.index(aUTF16.startIndex, offsetBy: count)
+            let bIdx = bUTF16.index(bUTF16.startIndex, offsetBy: count)
+            guard aUTF16[aIdx] == bUTF16[bIdx] else { break }
+            count += 1
+        }
+        return count
+    }
+}