From 2c2190b231458c04e2a95e18bdce4e42b5cf0d6e Mon Sep 17 00:00:00 2001
From: Lawrence Chen <54008264+lawrencecchen@users.noreply.github.com>
Date: Mon, 23 Feb 2026 18:33:19 -0800
Subject: [PATCH] Block tab drags across cmux app instances

---
 Sources/ContentView.swift | 26 ++++++++++++++++++++++++--
 vendor/bonsplit           |  2 +-
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/Sources/ContentView.swift b/Sources/ContentView.swift
index 9c73af0e..50ebfd3c 100644
--- a/Sources/ContentView.swift
+++ b/Sources/ContentView.swift
@@ -7194,6 +7194,7 @@ private enum SidebarTabDragPayload {
 
 private enum BonsplitTabDragPayload {
     static let typeIdentifier = "com.splittabbar.tabtransfer"
+    private static let currentProcessId = Int32(ProcessInfo.processInfo.processIdentifier)
 
     struct Transfer: Decodable {
         struct TabInfo: Decodable {
@@ -7202,6 +7203,25 @@ private enum BonsplitTabDragPayload {
 
         let tab: TabInfo
         let sourcePaneId: UUID
+        let sourceProcessId: Int32
+
+        private enum CodingKeys: String, CodingKey {
+            case tab
+            case sourcePaneId
+            case sourceProcessId
+        }
+
+        init(from decoder: Decoder) throws {
+            let container = try decoder.container(keyedBy: CodingKeys.self)
+            self.tab = try container.decode(TabInfo.self, forKey: .tab)
+            self.sourcePaneId = try container.decode(UUID.self, forKey: .sourcePaneId)
+            // Legacy payloads won't include this field. Treat as foreign process.
+            self.sourceProcessId = try container.decodeIfPresent(Int32.self, forKey: .sourceProcessId) ?? -1
+        }
+    }
+
+    private static func isCurrentProcessTransfer(_ transfer: Transfer) -> Bool {
+        transfer.sourceProcessId == currentProcessId
     }
 
     static func currentTransfer() -> Transfer? {
@@ -7209,13 +7229,15 @@ private enum BonsplitTabDragPayload {
         let type = NSPasteboard.PasteboardType(typeIdentifier)
 
         if let data = pasteboard.data(forType: type),
-           let transfer = try? JSONDecoder().decode(Transfer.self, from: data) {
+           let transfer = try? JSONDecoder().decode(Transfer.self, from: data),
+           isCurrentProcessTransfer(transfer) {
             return transfer
         }
 
         if let raw = pasteboard.string(forType: type),
            let data = raw.data(using: .utf8),
-           let transfer = try? JSONDecoder().decode(Transfer.self, from: data) {
+           let transfer = try? JSONDecoder().decode(Transfer.self, from: data),
+           isCurrentProcessTransfer(transfer) {
             return transfer
         }
 
diff --git a/vendor/bonsplit b/vendor/bonsplit
index 1ec5120d..f24ba922 160000
--- a/vendor/bonsplit
+++ b/vendor/bonsplit
@@ -1 +1 @@
-Subproject commit 1ec5120d94126f5c78e20618d426ee4ef5593c70
+Subproject commit f24ba9222651ecc170869662eec9a5880404a82c