Normalize newlines in single-line fields

FrameworkTests/SingleLineTextInputTests.swift

@@ -0,0 +1,56 @@
+import Foundation
+import SwiftUI
+import TermindPresentation
+import Testing
+
+@Suite("Single-line text editing")
+struct SingleLineTextInputTests {
+    @Test func attributedPasteKeepsSurroundingAttributesAndUnicodeOffsets() {
+        let key = NSAttributedString.Key("testStyle")
+        let original = NSMutableAttributedString(string: "👩🏽‍💻中文\r\n\nName", attributes: [key: "first"])
+        original.addAttribute(key, value: "second", range: NSRange(location: original.length - 4, length: 4))
+        let normalized = SingleLineTextInput.normalized(original)
+        #expect(normalized.string == "👩🏽‍💻中文 Name")
+        #expect(normalized.attribute(key, at: 0, effectiveRange: nil) as? String == "first")
+        #expect(normalized.attribute(key, at: normalized.length - 1, effectiveRange: nil) as? String == "second")
+        #expect(original.string == "👩🏽‍💻中文\r\n\nName")
+    }
+
+    @Test(arguments: ["\n", "\r", "\r\n", "\n\r\n", "\u{000B}", "\u{000C}", "\u{0085}", "\u{2028}", "\u{2029}"])
+    func consecutiveLineBreaksBecomeOneSpace(_ lineBreak: String) {
+        #expect(SingleLineTextInput.normalized("first\(lineBreak)second") == "first second")
+        #expect(SingleLineTextInput.normalized("\(lineBreak)first\(lineBreak)") == " first ")
+    }
+
+    @Test(arguments: ["", "example.invalid", "中文主机", "  two  spaces \t remain  ", "👩🏽‍💻服务器"])
+    func singleLineContentIsUnchanged(_ text: String) {
+        #expect(SingleLineTextInput.normalized(text) == text)
+    }
+
+    @Test func separatedLineBreakRunsKeepExistingSpacesAndTabs() {
+        #expect(SingleLineTextInput.normalized("a\r\n\n b\t\nc") == "a  b\t c")
+    }
+
+    @MainActor
+    @Test func bindingReadsLegacyValuesUnchangedAndNormalizesOnlyWrites() {
+        var stored = "legacy\nvalue"
+        var receivedTransaction: Transaction?
+        let source = Binding<String>(
+            get: { stored },
+            set: { value, transaction in
+                stored = value
+                receivedTransaction = transaction
+            }
+        )
+        let field = source.singleLineText
+        #expect(field.wrappedValue == "legacy\nvalue")
+        #expect(stored == "legacy\nvalue")
+        var transaction = Transaction()
+        transaction.disablesAnimations = true
+        field.transaction(transaction).wrappedValue = "新的\r\n\n名称"
+        #expect(stored == "新的 名称")
+        #expect(receivedTransaction?.disablesAnimations == true)
+        source.wrappedValue = "script\nbody"
+        #expect(stored == "script\nbody")
+    }
+}

Frameworks/TermindPresentation/ConnectionDecisionForms.swift

@@ -136,7 +136,8 @@ public struct SSHAuthenticationForm: View {
                     if identityID == nil {
                         GridRow {
                             Text("Username").foregroundStyle(.secondary)
-                            TextField("Username", text: usernameInput)
+                            TextField("Username", text: usernameInput.singleLineText, axis: .horizontal)
+                                .singleLinePaste().lineLimit(1)
                                 .focused($focusedField, equals: .username)
                         }
                         GridRow {

Frameworks/TermindPresentation/HostConnectionFields.swift

@@ -12,11 +12,15 @@ public struct HostConnectionFields: View {
     public var body: some View {
         Section("Connection") {
             LabeledContent("Name") {
-                TextField("Name", text: $host.name, prompt: Text(host.host)).labelsHidden().multilineTextAlignment(
-                    .trailing)
+                TextField("Name", text: $host.name.singleLineText, prompt: Text(host.host), axis: .horizontal)
+                    .singleLinePaste()
+                    .lineLimit(1).labelsHidden().multilineTextAlignment(
+                        .trailing)
             }
             LabeledContent("Host") {
-                TextField("Host", text: $host.host, prompt: Text("IP address or hostname"))
+                TextField(
+                    "Host", text: $host.host.singleLineText, prompt: Text("IP address or hostname"), axis: .horizontal
+                ).singleLinePaste().lineLimit(1)
                     .labelsHidden().multilineTextAlignment(.trailing)
                     #if os(iOS)
                         .textInputAutocapitalization(.never)
@@ -25,7 +29,7 @@ public struct HostConnectionFields: View {
                     #endif
             }
             LabeledContent("Port") {
-                TextField("Port", value: $host.port, format: .number.grouping(.never))
+                TextField("Port", value: $host.port, format: .number.grouping(.never)).lineLimit(1)
                     .labelsHidden().multilineTextAlignment(.trailing)
                     #if os(iOS)
                         .keyboardType(.numberPad)
@@ -34,7 +38,10 @@ public struct HostConnectionFields: View {
         }
         Section("SFTP") {
             LabeledContent("Initial Path") {
-                TextField("Initial Path", text: $host.sftpSessionInitialPath, prompt: Text("~"))
+                TextField(
+                    "Initial Path", text: $host.sftpSessionInitialPath.singleLineText, prompt: Text("~"),
+                    axis: .horizontal
+                ).singleLinePaste().lineLimit(1)
                     .labelsHidden().multilineTextAlignment(.trailing)
                     .font(.body.monospaced())
                     #if os(iOS)

Frameworks/TermindPresentation/ModelProviderConnectionFields.swift

@@ -16,7 +16,9 @@ public struct ModelProviderConnectionFields: View {
     public var body: some View {
         Section {
             LabeledContent("Name") {
-                TextField("Name", text: $name).labelsHidden().multilineTextAlignment(.trailing)
+                TextField("Name", text: $name.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
+                    .labelsHidden()
+                    .multilineTextAlignment(.trailing)
             }
             Toggle("Enabled", isOn: $isEnabled)
             Picker("API Type", selection: $endpoint.apiType) {
@@ -25,7 +27,9 @@ public struct ModelProviderConnectionFields: View {
         }
         Section("Endpoint") {
             LabeledContent("URL") {
-                TextField("URL", text: $endpoint.url).labelsHidden().autocorrectionDisabled()
+                TextField("URL", text: $endpoint.url.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
+                    .labelsHidden()
+                    .autocorrectionDisabled()
                     .multilineTextAlignment(.trailing)
             }
             if endpoint.isConfigured {

Frameworks/TermindPresentation/PortForwardingFields.swift

@@ -7,14 +7,20 @@ public struct PortForwardingFields: View {
 
     public var body: some View {
         Section("Port Forwarding") {
-            TextField("Name", text: $rule.label).textFieldStyle(.automatic).multilineTextAlignment(.leading)
+            TextField("Name", text: $rule.label.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
+                .textFieldStyle(
+                    .automatic
+                ).multilineTextAlignment(.leading)
             PortForwardingDirectionPicker(kind: $rule.kind)
             Text(directionDescription).font(.caption).foregroundStyle(.secondary)
             LabeledContent("Bind Address") {
-                TextField("Bind Address", text: $rule.bindHost).labelsHidden().multilineTextAlignment(.trailing)
+                TextField("Bind Address", text: $rule.bindHost.singleLineText, axis: .horizontal).singleLinePaste()
+                    .lineLimit(1)
+                    .labelsHidden().multilineTextAlignment(.trailing)
             }
             LabeledContent("Bind Port") {
-                TextField("Bind Port", value: $rule.bindPort, format: .number.grouping(.never)).labelsHidden()
+                TextField("Bind Port", value: $rule.bindPort, format: .number.grouping(.never)).lineLimit(1)
+                    .labelsHidden()
                     .multilineTextAlignment(.trailing)
                     #if os(iOS)
                         .keyboardType(.numberPad)
@@ -25,13 +31,14 @@ public struct PortForwardingFields: View {
                     TextField(
                         "Target Host",
                         text: Binding(get: { rule.targetHost ?? "localhost" }, set: { rule.targetHost = $0 })
-                    ).labelsHidden().multilineTextAlignment(.trailing)
+                            .singleLineText, axis: .horizontal
+                    ).singleLinePaste().lineLimit(1).labelsHidden().multilineTextAlignment(.trailing)
                 }
                 LabeledContent("Target Port") {
                     TextField(
                         "Target Port", value: Binding(get: { rule.targetPort ?? 80 }, set: { rule.targetPort = $0 }),
                         format: .number.grouping(.never)
-                    ).labelsHidden().multilineTextAlignment(.trailing)
+                    ).lineLimit(1).labelsHidden().multilineTextAlignment(.trailing)
                         #if os(iOS)
                             .keyboardType(.numberPad)
                         #endif

Frameworks/TermindPresentation/SingleLineTextInput.swift

@@ -0,0 +1,104 @@
+import Foundation
+import SwiftUI
+import UniformTypeIdentifiers
+
+/// Editing policy for single-line UI fields, not a transformation of stored data or secrets.
+public nonisolated enum SingleLineTextInput {
+    /// Preserve pasted attributes while replacing only newline runs.
+    public static func normalized(_ text: NSAttributedString) -> NSAttributedString {
+        let string = text.string
+        guard string.unicodeScalars.contains(where: { CharacterSet.newlines.contains($0) }) else { return text }
+        var ranges: [NSRange] = []
+        var offset = 0
+        var start: Int?
+        for scalar in string.unicodeScalars {
+            if CharacterSet.newlines.contains(scalar) {
+                if start == nil { start = offset }
+            } else if let runStart = start {
+                ranges.append(NSRange(location: runStart, length: offset - runStart))
+                start = nil
+            }
+            offset += scalar.utf16.count
+        }
+        if let start { ranges.append(NSRange(location: start, length: offset - start)) }
+        let result = NSMutableAttributedString(attributedString: text)
+        for range in ranges.reversed() { result.replaceCharacters(in: range, with: " ") }
+        return result
+    }
+
+    public static func normalized(_ text: String) -> String {
+        guard text.unicodeScalars.contains(where: { CharacterSet.newlines.contains($0) }) else { return text }
+        var result = ""
+        result.reserveCapacity(text.utf8.count)
+        var isInLineBreak = false
+        for scalar in text.unicodeScalars {
+            if CharacterSet.newlines.contains(scalar) {
+                if !isInLineBreak { result.append(" ") }
+                isInLineBreak = true
+            } else {
+                result.unicodeScalars.append(scalar)
+                isInLineBreak = false
+            }
+        }
+        return result
+    }
+}
+
+extension Binding where Value == String {
+    /// Read the original value unchanged; normalize only user edits, preserving the transaction.
+    public var singleLineText: Binding<String> {
+        Binding(
+            get: { wrappedValue },
+            set: { value, transaction in
+                self.transaction(transaction).wrappedValue = SingleLineTextInput.normalized(value)
+            }
+        )
+    }
+}
+
+private struct SingleLinePasteActionKey: EnvironmentKey {
+    static let defaultValue: (@MainActor @Sendable () -> Void)? = nil
+}
+
+private struct SingleLineInputAdapterKey: EnvironmentKey {
+    static let defaultValue: (@MainActor @Sendable () -> AnyView)? = nil
+}
+
+extension EnvironmentValues {
+    /// An app-owned adapter for native input that transforms text before native filtering.
+    public var singleLineInputAdapter: (@MainActor @Sendable () -> AnyView)? {
+        get { self[SingleLineInputAdapterKey.self] }
+        set { self[SingleLineInputAdapterKey.self] = newValue }
+    }
+
+    /// Platforms insert normalized clipboard text at the focused field's selection.
+    public var singleLinePasteAction: (@MainActor @Sendable () -> Void)? {
+        get { self[SingleLinePasteActionKey.self] }
+        set { self[SingleLinePasteActionKey.self] = newValue }
+    }
+}
+
+private struct SingleLinePasteModifier: ViewModifier {
+    @Environment(\.singleLinePasteAction) private var paste
+    @Environment(\.singleLineInputAdapter) private var adapter
+
+    @ViewBuilder
+    func body(content: Content) -> some View {
+        #if os(macOS)
+            if let paste {
+                content.onPasteCommand(of: [.text]) { _ in paste() }
+            } else {
+                content
+            }
+        #else
+            content.background {
+                if let adapter { adapter() }
+            }
+        #endif
+    }
+}
+
+extension View {
+    /// Normalize before native single-line controls flatten each newline separately.
+    public func singleLinePaste() -> some View { modifier(SingleLinePasteModifier()) }
+}

Memory/ARCHITECTURE.md

@@ -46,6 +46,14 @@ empty.
 
 ## State, navigation, and ownership
 
+Single-line UI fields share Presentation's newline-to-space editing policy and
+horizontal layout. Binding reads preserve stored values; only edits are normalized.
+App-owned native rename editors apply the same policy without interrupting marked
+text. Platforms inject app-owned single-line paste adapters so normalization happens
+before native controls flatten individual line breaks. Multiline content and secrets
+are excluded. Existing validation is unchanged. No persistence migration or bulk
+cleanup is performed.
+
 - Repository snapshots and preference models are application-wide. A window owns
   its shell, quick-open, search, navigation, and context-panel state.
 - Desktop navigation starts with Vault and Assistant, places Metrics above Vault

TFI/App/MobileRootView.swift

@@ -1,4 +1,5 @@
 import SwiftUI
+import TermindPresentation
 
 /// iPhone has four destinations. iPad retains the sidebar with individual library routes.
 struct MobileRootView: View {
@@ -51,6 +52,7 @@ struct MobileRootView: View {
                 .id(scene.selectedDestination ?? .vault)
             }
         }
+        .environment(\.singleLineInputAdapter, { AnyView(MobileSingleLineFieldInput()) })
         .sheet(isPresented: Binding(get: { app.pro.isPaywallPresented }, set: { app.pro.isPaywallPresented = $0 })) {
             MobileProView(pro: app.pro)
         }

TFI/Features/Assistant/MobileAssistantView.swift

@@ -1,6 +1,7 @@
 import AgentKit
 import SwiftUI
 import TermindApplication
+import TermindPresentation
 
 enum MobileAssistantLibraryRoute: String, Identifiable, Hashable {
     case conversations
@@ -101,7 +102,8 @@ struct MobileAssistantView: View {
                 "Rename",
                 isPresented: Binding(get: { renaming != nil }, set: { if !$0 { renaming = nil } })
             ) {
-                TextField("Conversation Name", text: $title)
+                TextField("Conversation Name", text: $title.singleLineText, axis: .horizontal).singleLinePaste()
+                    .lineLimit(1)
                 Button("Cancel", role: .cancel) { renaming = nil }
                 Button("Save") {
                     if let renaming { Task { await model.rename(renaming, title: title) } }
@@ -295,9 +297,10 @@ struct MobileAssistantLibrary: View {
             }
         }
         .navigationBarTitleDisplayMode(.inline)
-        .searchable(text: $query, prompt: "Search")
+        .searchable(text: $query.singleLineText, prompt: "Search")
         .alert("Rename", isPresented: Binding(get: { renaming != nil }, set: { if !$0 { renaming = nil } })) {
-            TextField("Conversation Name", text: $title)
+            TextField("Conversation Name", text: $title.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(
+                1)
             Button("Cancel", role: .cancel) { renaming = nil }
             Button("Save") {
                 if let renaming { Task { await model.rename(renaming, title: title) } }

TFI/Features/HostChooser/MobileConnectionPicker.swift

@@ -170,7 +170,7 @@ struct MobileHostPicker<Header: View>: View {
                 }
             }
         }
-        .searchable(text: $model.query, prompt: "Search hosts")
+        .searchable(text: $model.query.singleLineText, prompt: "Search hosts")
         .navigationTitle(Text(title))
         .navigationBarTitleDisplayMode(.inline)
         .toolbar {

TFI/Features/HostEditor/MobileHostEditor.swift

@@ -54,7 +54,9 @@ struct MobileHostEditor: View {
                     }
                     if draft.proxy != nil {
                         LabeledContent("Hostname") {
-                            TextField("Hostname", text: proxyString(\.hostname))
+                            TextField("Hostname", text: proxyString(\.hostname).singleLineText, axis: .horizontal)
+                                .singleLinePaste()
+                                .lineLimit(1)
                                 .textInputAutocapitalization(.never)
                                 .autocorrectionDisabled()
                                 .keyboardType(.URL)
@@ -62,7 +64,7 @@ struct MobileHostEditor: View {
                         }
                         .accessibilityLabel("Proxy Hostname")
                         LabeledContent("Port") {
-                            TextField("Port", value: proxyInt(\.port), format: .number.grouping(.never))
+                            TextField("Port", value: proxyInt(\.port), format: .number.grouping(.never)).lineLimit(1)
                                 .keyboardType(.numberPad)
                                 .multilineTextAlignment(.trailing)
                         }
@@ -76,7 +78,9 @@ struct MobileHostEditor: View {
                         .accessibilityLabel("Proxy Identity")
                         if draft.proxy?.identityID != nil {
                             LabeledContent("Username") {
-                                TextField("Username", text: proxyString(\.username))
+                                TextField("Username", text: proxyString(\.username).singleLineText, axis: .horizontal)
+                                    .singleLinePaste()
+                                    .lineLimit(1)
                                     .textInputAutocapitalization(.never)
                                     .autocorrectionDisabled()
                                     .multilineTextAlignment(.trailing)

TFI/Features/Keychain/MobileCredentialsView.swift

@@ -71,7 +71,7 @@ struct MobileCredentialsView: View {
                 }
             }
         }
-        .searchable(text: $query)
+        .searchable(text: $query.singleLineText)
         .navigationTitle("Keychain")
         .toolbar {
             Menu {
@@ -304,11 +304,15 @@ private struct MobileIdentityEditor: View {
             content: {
                 Section("Identity") {
                     LabeledContent("Name") {
-                        TextField("Name", text: $draft.name, prompt: Text(draft.username))
+                        TextField(
+                            "Name", text: $draft.name.singleLineText, prompt: Text(draft.username), axis: .horizontal
+                        ).singleLinePaste().lineLimit(1)
                             .multilineTextAlignment(.trailing)
                     }
                     LabeledContent("Username") {
-                        TextField("Username", text: $draft.username).textInputAutocapitalization(.never)
+                        TextField("Username", text: $draft.username.singleLineText, axis: .horizontal).singleLinePaste()
+                            .lineLimit(1)
+                            .textInputAutocapitalization(.never)
                             .autocorrectionDisabled().multilineTextAlignment(.trailing)
                     }
                 }

TFI/Features/Keychain/MobileKeyEditor.swift

@@ -17,7 +17,10 @@ struct MobileKeyEditor: View {
             content: {
                 Section("Key") {
                     LabeledContent("Name") {
-                        TextField("Name", text: $model.label, prompt: Text(model.defaultName))
+                        TextField(
+                            "Name", text: $model.label.singleLineText, prompt: Text(model.defaultName),
+                            axis: .horizontal
+                        ).singleLinePaste().lineLimit(1)
                             .multilineTextAlignment(.trailing)
                     }
                     if !model.isEnclave {
@@ -65,7 +68,7 @@ struct MobileKeyEditor: View {
                                     ForEach(SSHKeyMaterial.Cipher.allCases) { Text($0.displayName).tag($0) }
                                 }
                                 LabeledContent("Rounds") {
-                                    TextField("Rounds", value: $model.rounds, format: .number)
+                                    TextField("Rounds", value: $model.rounds, format: .number).lineLimit(1)
                                         .multilineTextAlignment(.trailing).keyboardType(.numberPad)
                                 }
                                 if model.passphrase != model.confirmation {

TFI/Features/KnownHosts/MobileKnownHostsView.swift

@@ -62,7 +62,7 @@ struct MobileKnownHostsView: View {
                 }
             }
         }
-        .searchable(text: $query)
+        .searchable(text: $query.singleLineText)
         .navigationTitle("Known Hosts")
         .sheet(item: $editing) { MobileKnownHostEditor(app: app, entry: $0) }
         .confirmationDialog(
@@ -101,14 +101,15 @@ struct MobileKnownHostEditor: View {
             content: {
                 Section {
                     LabeledContent("Hostname") {
-                        TextField("Hostname", text: $draft.hostname)
+                        TextField("Hostname", text: $draft.hostname.singleLineText, axis: .horizontal).singleLinePaste()
+                            .lineLimit(1)
                             .multilineTextAlignment(.trailing)
                             .textInputAutocapitalization(.never)
                             .autocorrectionDisabled()
                     }
                     if !draft.isHashed {
                         LabeledContent("Port") {
-                            TextField("Port", value: $draft.port, format: .number.grouping(.never))
+                            TextField("Port", value: $draft.port, format: .number.grouping(.never)).lineLimit(1)
                                 .multilineTextAlignment(.trailing)
                                 .keyboardType(.numberPad)
                         }
@@ -117,11 +118,13 @@ struct MobileKnownHostEditor: View {
                         ForEach(SSHKeyAlgorithm.allCases) { Text($0.displayName).tag($0) }
                     }
                     LabeledContent("Fingerprint") {
-                        TextField("Fingerprint", text: $draft.fingerprint)
-                            .multilineTextAlignment(.trailing)
-                            .font(.body.monospaced())
-                            .textInputAutocapitalization(.never)
-                            .autocorrectionDisabled()
+                        TextField("Fingerprint", text: $draft.fingerprint.singleLineText, axis: .horizontal).lineLimit(
+                            1
+                        )
+                        .multilineTextAlignment(.trailing)
+                        .font(.body.monospaced())
+                        .textInputAutocapitalization(.never)
+                        .autocorrectionDisabled()
                     }
                 }
                 if draft.isHashed {

TFI/Features/SFTP/MobileRemoteFileEditor.swift

@@ -35,7 +35,8 @@ struct MobileRemoteFileEditor: View {
             content: {
                 Section { Text(file.path).font(.caption.monospaced()).textSelection(.enabled) }
                 if mode == .rename {
-                    TextField("Name", text: $name).textInputAutocapitalization(.never).autocorrectionDisabled()
+                    TextField("Name", text: $name.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
+                        .textInputAutocapitalization(.never).autocorrectionDisabled()
                         .multilineTextAlignment(.leading)
                 } else {
                     Section("Permissions") {
@@ -44,10 +45,10 @@ struct MobileRemoteFileEditor: View {
                             text: Binding(
                                 get: { permissions.text },
                                 set: { _ = permissions.accept($0) }
-                            )
-                        )
-                        .font(.body.monospaced())
-                        .keyboardType(.numberPad)
+                            ).singleLineText, axis: .horizontal
+                        ).singleLinePaste().lineLimit(1)
+                            .font(.body.monospaced())
+                            .keyboardType(.numberPad)
                     }
                     Section("File Access") { UnixPermissionGrid(draft: $permissions) }
                     Section("Ownership") {

TFI/Features/SFTP/MobileSFTPBrowser.swift

@@ -155,7 +155,8 @@ private struct MobileSFTPPathBar: View {
     var body: some View {
         Group {
             if editsPath {
-                TextField("Remote Path", text: $session.pathText)
+                TextField("Remote Path", text: $session.pathText.singleLineText, axis: .horizontal).singleLinePaste()
+                    .lineLimit(1)
                     .font(.body.monospaced())
                     .textInputAutocapitalization(.never)
                     .autocorrectionDisabled()

TFI/Features/SFTP/MobileSFTPHistoryView.swift

@@ -1,5 +1,6 @@
 import SwiftUI
 import TermindDomain
+import TermindPresentation
 import UIKit
 
 struct MobileSFTPHistoryView: View {
@@ -65,7 +66,7 @@ struct MobileSFTPHistoryView: View {
                         .background(.bar)
                 }
             }
-            .searchable(text: $query, prompt: "Search History")
+            .searchable(text: $query.singleLineText, prompt: "Search History")
             .navigationTitle("History")
             .toolbar {
                 ToolbarItem(placement: .cancellationAction) {

TFI/Features/Settings/MobileAISettingsView.swift

@@ -239,7 +239,7 @@ struct MobileProviderEditor: View {
 
     private var modelSection: some View {
         Section("Models") {
-            TextField("Filter", text: $query)
+            TextField("Filter", text: $query.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
                 .textFieldStyle(.plain)
                 .multilineTextAlignment(.leading)
                 .textInputAutocapitalization(.never)
@@ -411,7 +411,7 @@ struct MobileModelFetchSheet: View {
                     }
                 }
             }
-            .searchable(text: $query, prompt: "Filter")
+            .searchable(text: $query.singleLineText, prompt: "Filter")
             .textInputAutocapitalization(.never)
             .autocorrectionDisabled()
             .background(Color(uiColor: .systemBackground))
@@ -451,10 +451,12 @@ struct MobileAddModelSheet: View {
         NavigationStack {
             Form {
                 Section("Model ID") {
-                    TextField("Model ID", text: $modelID)
-                        .textFieldStyle(.plain).multilineTextAlignment(.leading)
-                        .textInputAutocapitalization(.never).autocorrectionDisabled()
-                        .focused($focused).onSubmit(submit)
+                    TextField("Model ID", text: $modelID.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(
+                        1
+                    )
+                    .textFieldStyle(.plain).multilineTextAlignment(.leading)
+                    .textInputAutocapitalization(.never).autocorrectionDisabled()
+                    .focused($focused).onSubmit(submit)
                     if existing.contains(trimmedID) { Text("Added").foregroundStyle(.secondary) }
                 }
             }

TFI/Features/Settings/MobileMCPSettings.swift

@@ -2,6 +2,7 @@ import AgentKit
 import SwiftUI
 import TermindApplication
 import TermindInfrastructure
+import TermindPresentation
 
 struct MobileMCPSettings: View {
     let ai: AIConfigurationModel
@@ -205,7 +206,9 @@ struct MobileMCPEditor: View {
         Form {
             Section("Connection") {
                 LabeledContent("Name") {
-                    TextField("Name", text: $model.draft.name).multilineTextAlignment(.trailing)
+                    TextField("Name", text: $model.draft.name.singleLineText, axis: .horizontal).singleLinePaste()
+                        .lineLimit(1)
+                        .multilineTextAlignment(.trailing)
                 }
                 Toggle("Enabled", isOn: $model.draft.isEnabled)
                 LabeledContent("ID") {
@@ -222,7 +225,8 @@ struct MobileMCPEditor: View {
                     ForEach(MCPServer.Transport.allCases) { Text($0.displayName).tag($0) }
                 }
                 LabeledContent("URL") {
-                    TextField("MCP endpoint URL", text: $model.draft.url)
+                    TextField("MCP endpoint URL", text: $model.draft.url.singleLineText, axis: .horizontal)
+                        .singleLinePaste().lineLimit(1)
                         .textInputAutocapitalization(.never).autocorrectionDisabled().keyboardType(.URL)
                         .multilineTextAlignment(.trailing)
                 }
@@ -397,12 +401,14 @@ private struct MobileMCPHeaderEditor: View {
         Form {
             Section {
                 LabeledContent("Name") {
-                    TextField("Header name", text: $draft.name)
+                    TextField("Header name", text: $draft.name.singleLineText, axis: .horizontal).singleLinePaste()
+                        .lineLimit(1)
                         .focused($focusedField, equals: .name)
                         .multilineTextAlignment(.trailing)
                 }
                 LabeledContent("Value") {
-                    TextField("Header value", text: $draft.value)
+                    TextField("Header value", text: $draft.value.singleLineText, axis: .horizontal).singleLinePaste()
+                        .lineLimit(1)
                         .focused($focusedField, equals: .value)
                         .multilineTextAlignment(.trailing)
                 }

TFI/Features/Settings/MobileModelFields.swift

@@ -1,6 +1,7 @@
 import AgentKit
 import SwiftUI
 import TermindDomain
+import TermindPresentation
 
 struct MobileModelFields: View {
     @Binding var model: AIModel
@@ -9,7 +10,9 @@ struct MobileModelFields: View {
     var body: some View {
         Section {
             LabeledContent("Name") {
-                TextField("Name", text: $model.displayName).multilineTextAlignment(.trailing)
+                TextField("Name", text: $model.displayName.singleLineText, axis: .horizontal).singleLinePaste()
+                    .lineLimit(1)
+                    .multilineTextAlignment(.trailing)
             }
             Picker("Type", selection: $model.kind) {
                 ForEach(AIModel.Kind.allCases) { Text($0.displayName).tag($0) }
@@ -54,11 +57,11 @@ struct MobileModelFields: View {
 
         Section("Limits") {
             LabeledContent("Context Window") {
-                TextField("Context Window", value: $model.contextLength, format: .number)
+                TextField("Context Window", value: $model.contextLength, format: .number).lineLimit(1)
                     .multilineTextAlignment(.trailing).keyboardType(.numberPad)
             }
             LabeledContent("Max Output") {
-                TextField("Max Output", value: $model.maxOutputTokens, format: .number)
+                TextField("Max Output", value: $model.maxOutputTokens, format: .number).lineLimit(1)
                     .multilineTextAlignment(.trailing).keyboardType(.numberPad)
             }
         }
@@ -118,14 +121,14 @@ struct MobileModelFields: View {
                             for: effort
                         )
                     }
-                )
-            )
-            .textFieldStyle(.roundedBorder)
-            .textInputAutocapitalization(.never)
-            .autocorrectionDisabled()
-            .disabled(!mapping.isSupported)
-            .opacity(mapping.isSupported ? 1 : 0.55)
-            .accessibilityLabel(Text("\(effort.displayName) provider value"))
+                ).singleLineText, axis: .horizontal
+            ).singleLinePaste().lineLimit(1)
+                .textFieldStyle(.roundedBorder)
+                .textInputAutocapitalization(.never)
+                .autocorrectionDisabled()
+                .disabled(!mapping.isSupported)
+                .opacity(mapping.isSupported ? 1 : 0.55)
+                .accessibilityLabel(Text("\(effort.displayName) provider value"))
         }
     }
 

TFI/Features/Settings/MobileSkillSettings.swift

@@ -148,7 +148,9 @@ struct MobileSkillEditor: View {
             content: {
                 Section("Skill") {
                     LabeledContent("Title") {
-                        TextField("Title", text: $model.draft.title).multilineTextAlignment(.trailing)
+                        TextField("Title", text: $model.draft.title.singleLineText, axis: .horizontal).singleLinePaste()
+                            .lineLimit(1)
+                            .multilineTextAlignment(.trailing)
                     }
                     LabeledContent("Name") {
                         Text(

TFI/Features/Snippets/MobileSnippetsView.swift

@@ -1,6 +1,7 @@
 import SwiftUI
 import TermindApplication
 import TermindDomain
+import TermindPresentation
 
 import struct TermindDomain.Host
 
@@ -76,7 +77,7 @@ struct MobileSnippetsView: View {
                 }
             }
         }
-        .searchable(text: $query)
+        .searchable(text: $query.singleLineText)
         .navigationTitle("Snippets")
         .toolbar {
             ToolbarItem(placement: .primaryAction) {
@@ -613,7 +614,8 @@ struct MobileSnippetEditor: View {
             save: save
         ) {
             Section {
-                TextField("Title", text: $draft.title).multilineTextAlignment(.leading)
+                TextField("Title", text: $draft.title.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
+                    .multilineTextAlignment(.leading)
                 TextEditor(text: $draft.body).multilineTextAlignment(.leading)
                     .font(.body.monospaced()).frame(minHeight: 220)
                     .textInputAutocapitalization(.never).autocorrectionDisabled()
@@ -726,7 +728,9 @@ struct MobileSnippetPackageEditor: View {
             isDirty: draft != original, canSave: !trimmedName.isEmpty, compact: true,
             save: save
         ) {
-            TextField("Name", text: $draft.name).multilineTextAlignment(.leading)
+            TextField("Name", text: $draft.name.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
+                .multilineTextAlignment(
+                    .leading)
             Picker("Inside", selection: $draft.parentID) {
                 Text("Top Level").tag(SnippetPackage.ID?.none)
                 ForEach(parentChoices, id: \.package.id) { choice in
@@ -834,7 +838,7 @@ struct MobileSnippetHostPicker: View {
                     }
                 }
             }
-            .searchable(text: $query, prompt: "Search hosts")
+            .searchable(text: $query.singleLineText, prompt: "Search hosts")
             .navigationTitle(Text(title))
             .navigationBarTitleDisplayMode(.inline)
             .toolbar {

TFI/Features/Terminal/MobileCommandHistoryView.swift

@@ -63,7 +63,7 @@ struct MobileCommandHistoryView: View {
                         .background(.bar)
                 }
             }
-            .searchable(text: $query)
+            .searchable(text: $query.singleLineText)
             .navigationTitle("History")
             .toolbar {
                 ToolbarItem(placement: .cancellationAction) {

TFI/Features/Terminal/MobileTerminalSnippetsView.swift

@@ -1,6 +1,7 @@
 import SwiftUI
 import TermindApplication
 import TermindDomain
+import TermindPresentation
 import UIKit
 
 struct MobileTerminalSnippetsView: View {
@@ -40,7 +41,7 @@ struct MobileTerminalSnippetsView: View {
                 }
             }
             .background(Color(uiColor: .systemGroupedBackground))
-            .searchable(text: $query)
+            .searchable(text: $query.singleLineText)
             .navigationTitle("Snippets")
             .toolbar {
                 ToolbarItem(placement: .cancellationAction) {

TFI/Features/Vault/MobileVaultView.swift

@@ -227,7 +227,7 @@ struct MobileVaultView: View {
                 searchResults
             }
         }
-        .searchable(text: $query)
+        .searchable(text: $query.singleLineText)
         .navigationTitle("Vault")
         .toolbar {
             ToolbarItem(placement: .primaryAction) {
@@ -249,7 +249,7 @@ struct MobileVaultView: View {
                     if let error = app.library.storageError { throw MobileEditorError.message(error) }
                     groupName = ""
                 }
-            ) { TextField("Name", text: $groupName) }
+            ) { TextField("Name", text: $groupName.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1) }
         }
         .confirmationDialog(
             "Delete Host?", isPresented: Binding(get: { deletingHost != nil }, set: { if !$0 { deletingHost = nil } }),

TFI/Features/Workspaces/MobileWorkspaceRenameView.swift

@@ -1,5 +1,6 @@
 import Foundation
 import SwiftUI
+import TermindPresentation
 
 struct MobileWorkspaceRenameView: View {
     let originalTitle: String
@@ -19,7 +20,10 @@ struct MobileWorkspaceRenameView: View {
             canSave: !normalizedTitle.isEmpty && normalizedTitle != originalTitle,
             compact: true,
             save: { save(normalizedTitle) },
-            content: { TextField("Workspace Name", text: $title) }
+            content: {
+                TextField("Workspace Name", text: $title.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(
+                    1)
+            }
         )
     }
 

TFI/Features/Workspaces/MobileWorkspaceView.swift

@@ -273,7 +273,7 @@ struct MobileWorkspaceView: View {
                 Text("Use this choice for all conflicts in this batch.")
             }
             .alert("New Folder", isPresented: $creatingDirectory) {
-                TextField("Name", text: $directoryName)
+                TextField("Name", text: $directoryName.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
                 Button("Create") {
                     Task {
                         await workspace.sftpSession.createDirectory(directoryName)

TFI/UI/Components/MobileSingleLineFieldInput.swift

@@ -0,0 +1,97 @@
+import SwiftUI
+import TermindPresentation
+import UIKit
+
+/// A field-scoped paste proxy; the original text-input delegate is never replaced.
+struct MobileSingleLineFieldInput: UIViewRepresentable {
+    final class Marker: UIView {
+        private weak var field: UITextField?
+        private let proxy = DelegateProxy()
+
+        override func didMoveToWindow() {
+            super.didMoveToWindow()
+            scheduleAttach()
+        }
+
+        func scheduleAttach() {
+            DispatchQueue.main.async { [weak self] in self?.attach() }
+        }
+
+        private func attach() {
+            guard window != nil else {
+                detach()
+                return
+            }
+            var ancestor = superview
+            while let view = ancestor {
+                if let candidate = findField(in: view) {
+                    guard !candidate.isSecureTextEntry else { return }
+                    if let existing = candidate.pasteDelegate as? DelegateProxy, existing !== proxy { return }
+                    if field !== candidate { detach() }
+                    field = candidate
+                    if candidate.pasteDelegate !== proxy {
+                        proxy.originalDelegate = candidate.pasteDelegate
+                        candidate.pasteDelegate = proxy
+                    }
+                    return
+                }
+                ancestor = view.superview
+            }
+        }
+
+        private func findField(in view: UIView) -> UITextField? {
+            if let field = view as? UITextField, field.convert(field.bounds, to: self).intersects(bounds) {
+                return field
+            }
+            return view.subviews.lazy.compactMap { self.findField(in: $0) }.first
+        }
+
+        func detach() {
+            if field?.pasteDelegate === proxy { field?.pasteDelegate = proxy.originalDelegate }
+            field = nil
+            proxy.originalDelegate = nil
+        }
+    }
+
+    // NSObject's selector lookup is nonisolated; UIKit's actual paste callback stays MainActor.
+    nonisolated final class DelegateProxy: NSObject, UITextPasteDelegate {
+        weak var originalDelegate: (any UITextPasteDelegate)?
+
+        override func responds(to selector: Selector!) -> Bool {
+            super.responds(to: selector) || originalDelegate?.responds(to: selector) == true
+        }
+
+        override func forwardingTarget(for selector: Selector!) -> Any? {
+            if originalDelegate?.responds(to: selector) == true { return originalDelegate }
+            return super.forwardingTarget(for: selector)
+        }
+
+        @MainActor
+        func textPasteConfigurationSupporting(
+            _ textPasteConfigurationSupporting: any UITextPasteConfigurationSupporting,
+            combineItemAttributedStrings itemStrings: [NSAttributedString], for textRange: UITextRange
+        ) -> NSAttributedString {
+            let combined: NSAttributedString
+            if let original = originalDelegate?.textPasteConfigurationSupporting?(
+                textPasteConfigurationSupporting, combineItemAttributedStrings: itemStrings, for: textRange)
+            {
+                combined = original
+            } else {
+                let result = NSMutableAttributedString(string: "")
+                for item in itemStrings { result.append(item) }
+                combined = result
+            }
+            return SingleLineTextInput.normalized(combined)
+        }
+    }
+
+    func makeUIView(context: Context) -> Marker {
+        let view = Marker()
+        view.isUserInteractionEnabled = false
+        return view
+    }
+
+    func updateUIView(_ view: Marker, context: Context) { view.scheduleAttach() }
+
+    static func dismantleUIView(_ view: Marker, coordinator: ()) { view.detach() }
+}

TFI/UI/Components/MobileToolbarSearch.swift

@@ -1,13 +1,14 @@
 import SwiftUI
+import TermindPresentation
 
 extension View {
     @ViewBuilder
     func mobileToolbarSearch(text: Binding<String>, prompt: Text? = nil) -> some View {
         if #available(iOS 26.0, *) {
-            searchable(text: text, placement: .toolbar, prompt: prompt)
+            searchable(text: text.singleLineText, placement: .toolbar, prompt: prompt)
                 .searchToolbarBehavior(.minimize)
         } else {
-            searchable(text: text, placement: .toolbar, prompt: prompt)
+            searchable(text: text.singleLineText, placement: .toolbar, prompt: prompt)
         }
     }
 
@@ -18,10 +19,10 @@ extension View {
         prompt: Text? = nil
     ) -> some View {
         if #available(iOS 26.0, *) {
-            searchable(text: text, isPresented: isPresented, placement: .toolbar, prompt: prompt)
+            searchable(text: text.singleLineText, isPresented: isPresented, placement: .toolbar, prompt: prompt)
                 .searchToolbarBehavior(.minimize)
         } else {
-            searchable(text: text, isPresented: isPresented, placement: .toolbar, prompt: prompt)
+            searchable(text: text.singleLineText, isPresented: isPresented, placement: .toolbar, prompt: prompt)
         }
     }
 }

TFITests/MobileSingleLineFieldEditingTests.swift

@@ -0,0 +1,66 @@
+import SwiftUI
+import TermindDomain
+import TermindPresentation
+import Testing
+import UIKit
+
+@testable import TermindIOS
+
+@Suite("Mobile single-line field editing", .serialized)
+@MainActor
+struct MobileSingleLineFieldEditingTests {
+    @Test(arguments: ["en", "zh-Hans", "zh-Hant"])
+    func hostFormNormalizesPasteAndPreservesFocus(language: String) async throws {
+        let draft = MobileSingleLineHostTestDraft()
+        let controller = UIHostingController(
+            rootView: MobileSingleLineHostTestForm(draft: draft)
+                .environment(\.locale, Locale(identifier: language))
+                .environment(\.singleLineInputAdapter, { AnyView(MobileSingleLineFieldInput()) }))
+        let window = UIWindow(frame: CGRect(x: 0, y: 0, width: 520, height: 600))
+        window.rootViewController = controller
+        window.makeKeyAndVisible()
+        defer { window.isHidden = true }
+        controller.view.layoutIfNeeded()
+        try await Task.sleep(for: .milliseconds(100))
+        let field = try #require(findField(in: controller.view, value: "fixture.invalid"))
+        let inputDelegate = field.delegate
+        let pasteDelegate = try #require(field.pasteDelegate as? MobileSingleLineFieldInput.DelegateProxy)
+        #expect(field.becomeFirstResponder())
+        let selection = try #require(field.textRange(from: field.beginningOfDocument, to: field.endOfDocument))
+        field.selectedTextRange = selection
+        // Invoke the native paste transformation synchronously: other UI suites can
+        // change the key window while UIKit asynchronously loads item providers.
+        let pasted = pasteDelegate.textPasteConfigurationSupporting(
+            field, combineItemAttributedStrings: [NSAttributedString(string: "first.example\r\n\nsecond.example")],
+            for: selection)
+        field.insertText(pasted.string)
+        #expect(draft.host.host == "first.example second.example")
+        #expect(field.text == "first.example second.example")
+        #expect(field.isFirstResponder)
+        #expect(field.delegate === inputDelegate)
+        field.selectedTextRange = field.textRange(from: field.beginningOfDocument, to: field.endOfDocument)
+        let chineseSelection = try #require(field.selectedTextRange)
+        let chinesePaste = pasteDelegate.textPasteConfigurationSupporting(
+            field, combineItemAttributedStrings: [NSAttributedString(string: "中文\u{2028}名称")], for: chineseSelection)
+        field.insertText(chinesePaste.string)
+        #expect(draft.host.host == "中文 名称")
+        #expect(field.isFirstResponder)
+    }
+
+    private func findField(in view: UIView, value: String) -> UITextField? {
+        if let field = view as? UITextField, field.text == value { return field }
+        return view.subviews.lazy.compactMap { findField(in: $0, value: value) }.first
+    }
+}
+
+@Observable
+@MainActor
+private final class MobileSingleLineHostTestDraft {
+    var host = TermindDomain.Host(name: "Fixture", host: "fixture.invalid")
+}
+
+private struct MobileSingleLineHostTestForm: View {
+    @Bindable var draft: MobileSingleLineHostTestDraft
+
+    var body: some View { Form { HostConnectionFields(host: $draft.host) } }
+}

TFM/App/RootView.swift

@@ -1,6 +1,7 @@
 @preconcurrency import AppKit
 import SwiftUI
 import TermindApplication
+import TermindPresentation
 
 /// One window with one native Navigator column and one persistent detail deck.
 ///
@@ -58,6 +59,7 @@ struct RootView: View {
                 )
         }
         .navigationSplitViewStyle(.balanced)
+        .environment(\.singleLinePasteAction, { SingleLineFieldEditing.paste() })
         .background {
             MetricsWindowRegistration(model: window)
             WindowToolbarSearchHost()

TFM/Design/TagField.swift

@@ -1,5 +1,6 @@
 import SwiftUI
 import TermindApplication
+import TermindPresentation
 
 /// A token field: the tags already chosen, shown as removable chips, over a
 /// search field that narrows the tags in use elsewhere and offers to create the
@@ -78,7 +79,9 @@ struct TagField: View {
             Image(systemName: "number")
                 .foregroundStyle(.secondary)
 
-            TextField(text: $query, prompt: Text("Add a tag…")) { EmptyView() }
+            TextField(text: $query.singleLineText, prompt: Text("Add a tag…"), axis: .horizontal) { EmptyView() }
+                .singleLinePaste()
+                .lineLimit(1)
                 .textFieldStyle(.plain)
                 .labelsHidden()
                 .multilineTextAlignment(.leading)

TFM/Features/Assistant/AssistantView.swift

@@ -2,6 +2,7 @@ import AppKit
 import ListViewKit
 import SwiftUI
 import TermindApplication
+import TermindPresentation
 
 nonisolated enum AssistantSidebarEscapePolicy {
     static func shouldCloseConversation(
@@ -1340,8 +1341,8 @@ struct AssistantConversationRow: View {
                     controlActiveState: controlActiveState,
                     onSubmit: onCommitRename,
                     onCancel: onCancelRename
-                )
-                .frame(height: 18)
+                ).singleLinePaste()
+                    .frame(height: 18)
             } else {
                 Text(conversation.derivedTitle).lineLimit(1)
             }

TFM/Features/HostEditor/HostEditorView.swift

@@ -106,15 +106,16 @@ struct HostEditorView: View {
                 }
 
                 if draft.proxy != nil {
-                    TextField("Hostname", text: proxyString(\.hostname))
+                    TextField("Hostname", text: proxyString(\.hostname).singleLineText, axis: .horizontal)
+                        .singleLinePaste().lineLimit(1)
                         .padding(.leading, Metrics.Space.xxl)
                         .accessibilityLabel("Proxy Hostname")
                     TextField(
                         "Port", value: proxyInt(\.port),
                         format: .number.grouping(.never)
-                    )
-                    .padding(.leading, Metrics.Space.xxl)
-                    .accessibilityLabel("Proxy Port")
+                    ).lineLimit(1)
+                        .padding(.leading, Metrics.Space.xxl)
+                        .accessibilityLabel("Proxy Port")
                     Picker("Identity", selection: proxyIdentityChoice) {
                         Text("None").tag(Choice<Identity.ID>.unset)
                         ForEach(proxyIdentities) { identity in
@@ -127,7 +128,9 @@ struct HostEditorView: View {
                     .padding(.leading, Metrics.Space.xxl)
                     .accessibilityLabel("Proxy Identity")
                     if draft.proxy?.identityID != nil {
-                        TextField("Username", text: proxyString(\.username))
+                        TextField("Username", text: proxyString(\.username).singleLineText, axis: .horizontal)
+                            .singleLinePaste()
+                            .lineLimit(1)
                             .padding(.leading, Metrics.Space.xxl)
                             .accessibilityLabel("Proxy Username")
                     }

TFM/Features/Hosts/NewGroupSheet.swift

@@ -1,5 +1,6 @@
 import SwiftUI
 import TermindDomain
+import TermindPresentation
 
 /// Make or edit a group without leaving whatever raised the sheet — the
 /// companion to `NewIdentitySheet`, and the only place a group is ever edited.
@@ -64,7 +65,7 @@ struct NewGroupSheet: View {
     private var form: some View {
         Form {
             Section {
-                TextField("Name", text: $name)
+                TextField("Name", text: $name.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
 
                 // "Inside", not "Parent": the answer is where the group goes,
                 // and every other row here is phrased as a property of the

TFM/Features/Keychain/KeychainPageView.swift

@@ -422,7 +422,7 @@ private struct SoftwareKeyEditor: View {
                     }
 
                     Section("Key") {
-                        TextField("Name", text: $name)
+                        TextField("Name", text: $name.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
                         Picker("Store in", selection: $storage) {
                             Label("iCloud", systemImage: "icloud.fill").tag(KeyStorage.iCloud)
                             Label("This Mac", systemImage: "lock.laptopcomputer").tag(KeyStorage.thisDevice)
@@ -827,7 +827,8 @@ private struct GenerateKeySheet: View {
     var body: some View {
         VaultDetailScaffold(title: "Generate Key", symbol: "key.fill", close: close) {
             Form {
-                TextField("Name", text: $label, prompt: Text(defaultName))
+                TextField("Name", text: $label.singleLineText, prompt: Text(defaultName), axis: .horizontal).lineLimit(
+                    1)
                 Picker("Store in", selection: $storage) {
                     ForEach(availableStorage) { location in
                         Label(location.displayName, systemImage: location.symbol)
@@ -873,7 +874,7 @@ private struct GenerateKeySheet: View {
                                 Text(cipher.displayName).tag(cipher)
                             }
                         }
-                        TextField("Rounds", value: $rounds, format: .number)
+                        TextField("Rounds", value: $rounds, format: .number).lineLimit(1)
                     }
                     if !passwordsMatch {
                         Text("Passphrases do not match.")
@@ -1047,7 +1048,7 @@ private struct SecureEnclaveKeyEditor: View {
         VaultDetailScaffold(title: "Edit Key", symbol: "pencil", close: close) {
             Form {
                 Section("Key") {
-                    TextField("Name", text: $name)
+                    TextField("Name", text: $name.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
                     LabeledContent("Color") {
                         ColorTagPicker(selection: $colorTag, layout: .compact)
                     }
@@ -1157,7 +1158,8 @@ struct ExportKeyToHostsSheet: View {
             HStack(spacing: Metrics.Space.s) {
                 Image(systemName: "magnifyingglass")
                     .foregroundStyle(.secondary)
-                TextField("Search hosts", text: queryBinding)
+                TextField("Search hosts", text: queryBinding.singleLineText, axis: .horizontal).singleLinePaste()
+                    .lineLimit(1)
                     .textFieldStyle(.plain)
                     .focused($searchFocused)
                     .onKeyPress(.upArrow) { moveCursor(-1) }

TFM/Features/Keychain/NewIdentitySheet.swift

@@ -110,9 +110,10 @@ struct NewIdentitySheet: View {
         Form {
             Section {
                 if configuration.showsName {
-                    TextField("Name", text: $name, prompt: Text(username))
+                    TextField("Name", text: $name.singleLineText, prompt: Text(username), axis: .horizontal).lineLimit(
+                        1)
                 }
-                TextField("Username", text: $username)
+                TextField("Username", text: $username.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
 
                 // Both optional, and both allowed at once: a key to get in and a
                 // password the same account still asks for is an ordinary setup,

TFM/Features/KnownHosts/KnownHostsPageView.swift

@@ -159,12 +159,16 @@ struct KnownHostEditorView: View {
     var body: some View {
         VaultDetailScaffold(title: "Host Key", symbol: "touchid", close: window.closeVaultWork) {
             Form {
-                TextField("Hostname", text: $draft.hostname)
-                if !draft.isHashed { TextField("Port", value: $draft.port, format: .number.grouping(.never)) }
+                TextField("Hostname", text: $draft.hostname.singleLineText, axis: .horizontal).singleLinePaste()
+                    .lineLimit(1)
+                if !draft.isHashed {
+                    TextField("Port", value: $draft.port, format: .number.grouping(.never)).lineLimit(1)
+                }
                 Picker("Key Type", selection: $draft.algorithm) {
                     ForEach(SSHKeyAlgorithm.allCases) { Text($0.displayName).tag($0) }
                 }
-                TextField("Fingerprint", text: $draft.fingerprint)
+                TextField("Fingerprint", text: $draft.fingerprint.singleLineText, axis: .horizontal).singleLinePaste()
+                    .lineLimit(1)
                     .font(.body.monospaced())
                 if draft.isHashed {
                     Text("The original address and port cannot be recovered from this hash.").font(.caption)

TFM/Features/QuickOpen/QuickOpenView.swift

@@ -1,4 +1,5 @@
 import SwiftUI
+import TermindPresentation
 
 /// The window-level presentation for Command-P.
 ///
@@ -94,7 +95,9 @@ struct QuickOpenView: View {
                 .foregroundStyle(.secondary)
                 .accessibilityHidden(true)
 
-            TextField("Open a page, chat, workspace, host, or command", text: $query)
+            TextField("Open a page, chat, workspace, host, or command", text: $query.singleLineText, axis: .horizontal)
+                .singleLinePaste()
+                .lineLimit(1)
                 .textFieldStyle(.plain)
                 .font(.system(size: 17, weight: .medium))
                 .focused($searchFocused)

TFM/Features/SFTP/SFTPBrowserView.swift

@@ -306,7 +306,8 @@ struct SFTPBrowserView: View {
             }
         }
         .alert("New Folder", isPresented: $newFolderPresented) {
-            TextField("Folder Name", text: $newFolderName)
+            TextField("Folder Name", text: $newFolderName.singleLineText, axis: .horizontal).singleLinePaste()
+                .lineLimit(1)
             Button("Cancel", role: .cancel) {}
             Button("Create") {
                 let name = newFolderName
@@ -321,7 +322,7 @@ struct SFTPBrowserView: View {
                 set: { if !$0 { renameTarget = nil } }
             )
         ) {
-            TextField("Name", text: $renameName)
+            TextField("Name", text: $renameName.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
             Button("Cancel", role: .cancel) { renameTarget = nil }
             Button("Rename") {
                 guard let target = renameTarget else { return }
@@ -408,7 +409,8 @@ struct SFTPBrowserView: View {
                 }
 
                 if editsPath {
-                    TextField("Remote Path", text: $sftpSession.pathText)
+                    TextField("Remote Path", text: $sftpSession.pathText.singleLineText, axis: .horizontal)
+                        .singleLinePaste().lineLimit(1)
                         .textFieldStyle(.plain)
                         .font(.body.monospaced())
                         .focused($pathFocused)
@@ -1328,7 +1330,7 @@ private struct SFTPEditPermissionsSheet: View {
                         .truncationMode(.middle)
                         .help(displayedPath)
                     Spacer(minLength: Metrics.Space.xl)
-                    TextField("Mode", text: modeText)
+                    TextField("Mode", text: modeText.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
                         .labelsHidden()
                         .font(.body.monospacedDigit())
                         .multilineTextAlignment(.trailing)

TFM/Features/SSHImport/SSHImportView.swift

@@ -288,7 +288,8 @@ private struct SSHImportContent: View {
                                 editingNames.insert(item.id)
                                 model.setName($0, for: item.id)
                             }
-                        ))
+                        ).singleLineText, axis: .horizontal
+                    ).singleLinePaste().lineLimit(1)
                 }
                 let options = model.keyOptions(for: item)
                 if options.count > 1 {
@@ -312,7 +313,8 @@ private struct SSHImportContent: View {
                         text: Binding(
                             get: { binding.name.wrappedValue },
                             set: { model.setName($0, for: item.id) }
-                        ))
+                        ).singleLineText, axis: .horizontal
+                    ).singleLinePaste().lineLimit(1)
                 }
                 LabeledContent("Username", value: identity.username)
                 LabeledContent(

TFM/Features/Settings/MCPServerEditorSheet.swift

@@ -1,6 +1,7 @@
 import AgentKit
 import SwiftUI
 import TermindApplication
+import TermindPresentation
 
 @Observable
 final class MCPServerEditorSession {
@@ -86,7 +87,7 @@ struct MCPServerEditorPage: View {
     @ViewBuilder
     private func connectionSection(_ server: MCPServer) -> some View {
         Section {
-            TextField("Name", text: binding(\.name))
+            TextField("Name", text: binding(\.name).singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
             Toggle(
                 "Enabled",
                 isOn: Binding(
@@ -124,7 +125,9 @@ struct MCPServerEditorPage: View {
                 ForEach(MCPServer.Transport.allCases) { Text($0.displayName).tag($0) }
             }
 
-            TextField("URL", text: binding(\.url), prompt: Text("MCP endpoint URL"))
+            TextField("URL", text: binding(\.url).singleLineText, prompt: Text("MCP endpoint URL"), axis: .horizontal)
+                .singleLinePaste()
+                .lineLimit(1)
 
             Text(server.transport.detail)
                 .font(.caption)
@@ -199,9 +202,13 @@ struct MCPServerEditorPage: View {
             ForEach(server.headers) { header in
                 HStack(spacing: Metrics.Space.s) {
                     TextField(
-                        "Name", text: headerBinding(header.id, \.name), prompt: Text("Header name"))
+                        "Name", text: headerBinding(header.id, \.name).singleLineText, prompt: Text("Header name"),
+                        axis: .horizontal
+                    ).singleLinePaste().lineLimit(1)
                     TextField(
-                        "Value", text: headerBinding(header.id, \.value), prompt: Text("Header value"))
+                        "Value", text: headerBinding(header.id, \.value).singleLineText, prompt: Text("Header value"),
+                        axis: .horizontal
+                    ).singleLinePaste().lineLimit(1)
                     Button {
                         removeHeader(header.id)
                     } label: {

TFM/Features/Settings/MCPServerSettings.swift

@@ -1,5 +1,6 @@
 import SwiftUI
 import TermindDomain
+import TermindPresentation
 
 #if canImport(AppKit)
     import AppKit
@@ -37,9 +38,9 @@ struct MCPServerSettings: View {
                         get: { server.port },
                         set: { server.setPort($0) }
                     ), format: .number.grouping(.never)
-                )
-                .frame(width: 100)
-                .multilineTextAlignment(.trailing)
+                ).lineLimit(1)
+                    .frame(width: 100)
+                    .multilineTextAlignment(.trailing)
             }
             Text(
                 "The server listens only on 127.0.0.1 and ::1. It is off by default; when enabled, external calls execute without per-call approval."
@@ -98,7 +99,9 @@ struct MCPServerSettings: View {
         }
 
         Section("Call History") {
-            TextField("Filter by client, tool, host or argument", text: $historyQuery)
+            TextField("Filter by client, tool, host or argument", text: $historyQuery.singleLineText, axis: .horizontal)
+                .singleLinePaste()
+                .lineLimit(1)
             let rows = app.toolAudit.entries(matching: historyQuery)
             if rows.isEmpty {
                 ContentUnavailableView(

TFM/Features/Settings/ModelListEditor.swift

@@ -1,6 +1,7 @@
 import AgentKit
 import SwiftUI
 import TermindDomain
+import TermindPresentation
 
 /// A provider's full-width models page: a checkable list and details for the
 /// selected row.
@@ -117,10 +118,11 @@ struct ModelListEditor: View {
                 HStack(spacing: Metrics.Space.s) {
                     TextField(
                         "Exact model ID, such as gpt-5.4",
-                        text: Binding(get: { state.newModelID }, set: { state.newModelID = $0 })
-                    )
-                    .textFieldStyle(.roundedBorder)
-                    .onSubmit(addModel)
+                        text: Binding(get: { state.newModelID }, set: { state.newModelID = $0 }).singleLineText,
+                        axis: .horizontal
+                    ).singleLinePaste().lineLimit(1)
+                        .textFieldStyle(.roundedBorder)
+                        .onSubmit(addModel)
 
                     Button("Cancel") {
                         state.newModelID = ""
@@ -141,8 +143,9 @@ struct ModelListEditor: View {
         HStack(spacing: Metrics.Space.xs) {
             Image(systemName: "magnifyingglass").foregroundStyle(.secondary)
             TextField(
-                "Filter", text: Binding(get: { state.query }, set: { state.query = $0 })
-            ).textFieldStyle(.plain)
+                "Filter", text: Binding(get: { state.query }, set: { state.query = $0 }).singleLineText,
+                axis: .horizontal
+            ).singleLinePaste().lineLimit(1).textFieldStyle(.plain)
             if !state.query.isEmpty {
                 Button {
                     state.query = ""
@@ -335,7 +338,10 @@ struct ModelListEditor: View {
                             .fixedSize(horizontal: false, vertical: true)
                     }
 
-                    TextField("Name", text: field(model, \.displayName), prompt: Text(model.id))
+                    TextField(
+                        "Name", text: field(model, \.displayName).singleLineText, prompt: Text(model.id),
+                        axis: .horizontal
+                    ).singleLinePaste().lineLimit(1)
                         .textFieldStyle(.roundedBorder)
 
                     Picker("Type", selection: field(model, \.kind)) {
@@ -525,11 +531,11 @@ struct ModelListEditor: View {
                         updated.setReasoningWireValue(trimmed.isEmpty ? nil : value, for: effort)
                         app.aiConfiguration.updateModel(updated, in: modelProviderID)
                     }
-                )
-            )
-            .textFieldStyle(.roundedBorder)
-            .disabled(!mapping.isSupported)
-            .accessibilityLabel(Text("\(effort.displayName) provider value"))
+                ).singleLineText, axis: .horizontal
+            ).singleLinePaste().lineLimit(1)
+                .textFieldStyle(.roundedBorder)
+                .disabled(!mapping.isSupported)
+                .accessibilityLabel(Text("\(effort.displayName) provider value"))
         }
     }
 
@@ -553,9 +559,9 @@ struct ModelListEditor: View {
                     }
                 ),
                 format: .number
-            )
-            .labelsHidden()
-            .textFieldStyle(.roundedBorder)
+            ).lineLimit(1)
+                .labelsHidden()
+                .textFieldStyle(.roundedBorder)
         }
     }
 

TFM/Features/Settings/SkillEditorSheet.swift

@@ -70,7 +70,7 @@ struct SkillEditorPage: View {
     @ViewBuilder
     private func identitySection(_ skill: AgentSkill) -> some View {
         Section {
-            TextField("Title", text: binding(\.title))
+            TextField("Title", text: binding(\.title).singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
 
             if isNameLocked {
                 LabeledContent("Name") {

TFM/Features/Sidebar/WindowSidebarView.swift

@@ -843,18 +843,18 @@ private struct SSHCommandHistorySidebar: View {
                     prompt: String(localized: "Snippet Name"),
                     onSubmit: { saveSnippet(from: entry) },
                     onCancel: cancelSnippetNaming
-                )
-                .frame(height: 18)
-                .padding(.horizontal, Metrics.Space.s)
-                .padding(.vertical, 4)
-                .background(
-                    Color.primary.opacity(0.055),
-                    in: .rect(cornerRadius: Metrics.Radius.small)
-                )
-                .overlay {
-                    RoundedRectangle(cornerRadius: Metrics.Radius.small)
-                        .strokeBorder(Color.accentColor.opacity(0.55))
-                }
+                ).singleLinePaste()
+                    .frame(height: 18)
+                    .padding(.horizontal, Metrics.Space.s)
+                    .padding(.vertical, 4)
+                    .background(
+                        Color.primary.opacity(0.055),
+                        in: .rect(cornerRadius: Metrics.Radius.small)
+                    )
+                    .overlay {
+                        RoundedRectangle(cornerRadius: Metrics.Radius.small)
+                            .strokeBorder(Color.accentColor.opacity(0.55))
+                    }
                 Text(CommandHistoryPresentation.title(for: entry))
                     .font(.caption.monospaced())
                     .foregroundStyle(.secondary)
@@ -1342,6 +1342,7 @@ private struct SidebarInlineTextField: NSViewRepresentable {
         field.focusRingType = .none
         field.font = NSFont.preferredFont(forTextStyle: .body)
         field.lineBreakMode = .byTruncatingTail
+        field.cell?.usesSingleLineMode = true
         field.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
         context.coordinator.requestFocus(for: field)
         return field
@@ -1378,8 +1379,10 @@ private struct SidebarInlineTextField: NSViewRepresentable {
         }
 
         func controlTextDidChange(_ notification: Notification) {
-            guard let field = notification.object as? NSTextField else { return }
-            text.wrappedValue = field.stringValue
+            guard let field = notification.object as? NSTextField,
+                let value = SingleLineFieldEditing.normalizedValue(in: field)
+            else { return }
+            text.wrappedValue = value
         }
 
         func control(

TFM/Features/Snippets/SnippetsPageView.swift

@@ -1,6 +1,7 @@
 import SwiftUI
 import TermindApplication
 import TermindDomain
+import TermindPresentation
 
 import struct TermindDomain.Host
 
@@ -588,7 +589,7 @@ struct SnippetEditorSheet: View {
         ) {
             Form {
                 Section {
-                    TextField("Name", text: $title)
+                    TextField("Name", text: $title.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
                     VStack(alignment: .leading, spacing: Metrics.Space.s) {
                         Text("Script")
                             .font(.caption)
@@ -868,7 +869,7 @@ struct SnippetPackageSheet: View {
             symbol: "folder.fill", close: close
         ) {
             Form {
-                TextField("Name", text: $name)
+                TextField("Name", text: $name.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
                 Picker("Inside", selection: $parentID) {
                     Text("Top Level").tag(SnippetPackage.ID?.none)
                     ForEach(parentChoices, id: \.package.id) { choice in

TFM/Features/Terminal/SerialControls.swift

@@ -1,4 +1,5 @@
 import SwiftUI
+import TermindPresentation
 
 nonisolated struct SerialComboOption: Identifiable, Hashable, Sendable {
     let value: String
@@ -19,7 +20,7 @@ struct SerialEditableComboField: View {
     var body: some View {
         LabeledContent {
             HStack(spacing: 0) {
-                TextField("", text: $value)
+                TextField("", text: $value.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
                     .textFieldStyle(.plain)
                     .font(monospaced ? .body.monospaced() : .body)
                     .padding(.leading, Metrics.Space.m)

TFM/Features/Workspaces/WorkspaceContentView.swift

@@ -723,12 +723,14 @@ private struct PaneView: View {
                 .foregroundStyle(.secondary)
 
             if isRenaming {
-                TextField("Pane Name", text: $draftTitle)
-                    .textFieldStyle(.plain)
-                    .font(.system(size: 11, weight: .medium))
-                    .focused($titleFieldFocused)
-                    .onSubmit(commitRename)
-                    .onExitCommand { isRenaming = false }
+                TextField("Pane Name", text: $draftTitle.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(
+                    1
+                )
+                .textFieldStyle(.plain)
+                .font(.system(size: 11, weight: .medium))
+                .focused($titleFieldFocused)
+                .onSubmit(commitRename)
+                .onExitCommand { isRenaming = false }
             } else {
                 title
             }
@@ -1127,8 +1129,8 @@ private struct WelcomeWorkspaceTemplateRow: View {
                     controlActiveState: controlActiveState,
                     onSubmit: commitRename,
                     onCancel: cancelRename
-                )
-                .frame(height: 18)
+                ).singleLinePaste()
+                    .frame(height: 18)
             } else {
                 VStack(alignment: .leading, spacing: Metrics.Space.xs) {
                     Text(template.name)

TFM/Features/Workspaces/WorkspaceNavigatorView.swift

@@ -1,6 +1,7 @@
 import AppKit
 import SwiftUI
 import TermindApplication
+import TermindPresentation
 import UniformTypeIdentifiers
 
 /// The native source list for Vault and Workspaces.
@@ -414,8 +415,8 @@ private struct WorkspaceNavigatorRow: View {
                     controlActiveState: controlActiveState,
                     onSubmit: onCommitRename,
                     onCancel: onCancelRename
-                )
-                .frame(height: 18)
+                ).singleLinePaste()
+                    .frame(height: 18)
             } else {
                 VStack(alignment: .leading, spacing: 1) {
                     Text(workspace.title(in: app.hostLibrary, locale: locale))

TFM/Features/Workspaces/WorkspaceTemplateSupport.swift

@@ -2,6 +2,7 @@ import Foundation
 import SwiftUI
 import TermindApplication
 import TermindDomain
+import TermindPresentation
 
 extension Workspace {
     func workspaceTemplateLayout(in hosts: HostLibraryModel) -> WorkspaceTemplateLayout? {
@@ -162,7 +163,8 @@ struct WorkspaceTemplateNameSheet: View {
         VStack(alignment: .leading, spacing: Metrics.Space.l) {
             Text(title)
                 .font(.title2.weight(.semibold))
-            TextField("Workspace Name", text: $presentation.name)
+            TextField("Workspace Name", text: $presentation.name.singleLineText, axis: .horizontal).singleLinePaste()
+                .lineLimit(1)
                 .textFieldStyle(.roundedBorder)
                 .focused($isNameFocused)
             if let error = presentation.error {

TFM/UI/Components/ChromeComponents.swift

@@ -1,4 +1,5 @@
 import SwiftUI
+import TermindPresentation
 
 extension View {
     func termindTransientOverlaySurface() -> some View {
@@ -62,7 +63,7 @@ struct TermindSearchField: View {
         HStack(spacing: Metrics.Space.s) {
             Image(systemName: "magnifyingglass")
                 .foregroundStyle(.secondary)
-            TextField(prompt, text: $text)
+            TextField(prompt, text: $text.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
                 .textFieldStyle(.plain)
                 .font(density == .prominent ? .title3 : .body)
                 .focused(externalFocus ?? $localFocus)
@@ -205,7 +206,7 @@ struct ManagedChooserHeader: View {
         HStack(spacing: Metrics.Space.s) {
             Image(systemName: "magnifyingglass")
                 .foregroundStyle(.secondary)
-            TextField(prompt, text: $query)
+            TextField(prompt, text: $query.singleLineText, axis: .horizontal).singleLinePaste().lineLimit(1)
                 .textFieldStyle(.plain)
                 .focused($searchFocused)
                 .onSubmit(onSubmit)

TFM/UI/Components/SidebarRow.swift

@@ -1,5 +1,6 @@
 import AppKit
 import SwiftUI
+import TermindPresentation
 
 /// A transparent native field for inline renaming inside emphasized sidebar
 /// rows. Return commits, Escape cancels, and a pointer exit commits only after
@@ -103,8 +104,10 @@ struct SidebarInlineRenameField: NSViewRepresentable {
         }
 
         func controlTextDidChange(_ notification: Notification) {
-            guard let field = notification.object as? NSTextField else { return }
-            text.wrappedValue = field.stringValue
+            guard let field = notification.object as? NSTextField,
+                let value = SingleLineFieldEditing.normalizedValue(in: field)
+            else { return }
+            text.wrappedValue = value
         }
 
         func controlTextDidEndEditing(_: Notification) {
@@ -400,7 +403,7 @@ struct SidebarSearchFooter: View {
     var placeholder: String
 
     var body: some View {
-        NativeSearchField(text: $text, placeholder: placeholder, controlSize: .large)
+        NativeSearchField(text: $text, placeholder: placeholder, controlSize: .large).singleLinePaste()
             .frame(height: Metrics.Sidebar.searchFieldHeight)
             .padding(.horizontal, Metrics.Space.m)
             .padding(.vertical, Metrics.Space.s)

TFM/UI/Components/SingleLineFieldEditing.swift

@@ -0,0 +1,38 @@
+import AppKit
+import TermindPresentation
+
+/// Keep the native field editor and binding in sync without interrupting marked-text composition.
+enum SingleLineFieldEditing {
+    static func paste() {
+        guard let editor = NSApp.keyWindow?.firstResponder as? NSTextView,
+            let field = editor.delegate as? NSTextField, !(field is NSSecureTextField),
+            let text = NSPasteboard.general.string(forType: .string)
+        else { return }
+        insert(text, into: editor)
+    }
+
+    static func insert(_ text: String, into editor: NSTextView) {
+        editor.insertText(SingleLineTextInput.normalized(text), replacementRange: editor.selectedRange())
+    }
+
+    static func normalizedValue(in field: NSTextField) -> String? {
+        let editor = field.currentEditor() as? NSTextView
+        guard editor?.hasMarkedText() != true else { return nil }
+        let original = field.stringValue
+        let normalized = SingleLineTextInput.normalized(original)
+        guard original != normalized else { return original }
+        let selection = editor?.selectedRange()
+        field.stringValue = normalized
+        if let editor, let selection {
+            let originalString = original as NSString
+            let start = min(selection.location, originalString.length)
+            let end = start + min(selection.length, originalString.length - start)
+            let normalizedStart = (SingleLineTextInput.normalized(originalString.substring(to: start)) as NSString)
+                .length
+            let normalizedEnd = (SingleLineTextInput.normalized(originalString.substring(to: end)) as NSString).length
+            editor.string = normalized
+            editor.setSelectedRange(NSRange(location: normalizedStart, length: normalizedEnd - normalizedStart))
+        }
+        return normalized
+    }
+}

TFM/UI/Components/WindowToolbar.swift

@@ -2,6 +2,7 @@ import AppKit
 import SwiftUI
 import TermindApplication
 import TermindDomain
+import TermindPresentation
 
 import struct TermindDomain.Host
 
@@ -94,6 +95,7 @@ struct NativeSearchField: NSViewRepresentable {
         field.stringValue = text
         field.controlSize = controlSize
         field.focusRingType = .default
+        field.cell?.usesSingleLineMode = true
         // Filter as the user types. The default batches until Return, which for
         // a list that narrows in place means the field looks broken.
         field.sendsWholeSearchString = false
@@ -178,8 +180,10 @@ struct NativeSearchField: NSViewRepresentable {
         }
 
         func controlTextDidChange(_ notification: Notification) {
-            guard let searchField = notification.object as? NSSearchField else { return }
-            field.text = searchField.stringValue
+            guard let searchField = notification.object as? NSSearchField,
+                let value = SingleLineFieldEditing.normalizedValue(in: searchField)
+            else { return }
+            field.text = value
         }
 
         // MARK: Holding the keyboard
@@ -409,7 +413,7 @@ struct WindowToolbarSearchHost: View {
     private var searchableHost: some View {
         Color.clear
             .searchable(
-                text: searchText,
+                text: searchText.singleLineText,
                 isPresented: $isPresented,
                 placement: .automatic,
                 prompt: Text("Search")
@@ -487,12 +491,12 @@ struct WindowToolbarFindField: View {
                     cancel: context.cancel,
                     installFocusHandler: { window.focusToolbarFindField = $0 },
                     onFocusChange: { window.isToolbarFindFocused = $0 }
-                )
-                .frame(width: Metrics.Toolbar.searchFieldWidth)
-                .help(Text(AppLocalization.string("Search", locale: locale)))
-                .accessibilityLabel(
-                    Text(AppLocalization.string("Search", locale: locale))
-                )
+                ).singleLinePaste()
+                    .frame(width: Metrics.Toolbar.searchFieldWidth)
+                    .help(Text(AppLocalization.string("Search", locale: locale)))
+                    .accessibilityLabel(
+                        Text(AppLocalization.string("Search", locale: locale))
+                    )
             } else {
                 // Zero width, full height. A toolbar with nothing in it is
                 // shorter than one holding a search field, and the titlebar

TFMTests/ArchitectureBoundaryTests.swift

@@ -9,6 +9,29 @@ import Testing
 
 @Suite
 struct ArchitectureBoundaryTests {
+    @Test
+    func singleLineEditingIsSharedButNativeFieldEditorsRemainAppOwned() throws {
+        let root = sourceRoot.deletingLastPathComponent()
+        let policy = try String(
+            contentsOf: root.appending(path: "Frameworks/TermindPresentation/SingleLineTextInput.swift"),
+            encoding: .utf8)
+        for forbidden in ["import AppKit", "import UIKit", "import TermindPersistence", "import AgentKit"] {
+            #expect(!policy.contains(forbidden))
+        }
+        let native = try String(
+            contentsOf: sourceRoot.appending(path: "UI/Components/SingleLineFieldEditing.swift"), encoding: .utf8)
+        #expect(native.contains("SingleLineTextInput.normalized"))
+        #expect(native.contains("hasMarkedText()"))
+        for path in [
+            "TFM/Features/AI/ConversationTranscriptView.swift",
+            "TFI/Features/AI/MobileAssistantComposer.swift",
+            "TFI/Features/AI/MobileAssistantInteraction.swift",
+        ] {
+            let content = try String(contentsOf: root.appending(path: path), encoding: .utf8)
+            #expect(!content.contains(".singleLineText"))
+        }
+    }
+
     @Test
     func aiSettingsUsePortableModelsAndSyncedSkills() throws {
         let root = sourceRoot.deletingLastPathComponent()

TFMTests/SingleLineFieldEditingTests.swift

@@ -0,0 +1,120 @@
+import AppKit
+import SwiftUI
+import TermindDomain
+import TermindPresentation
+import Testing
+
+@testable import Termind
+
+@Suite("Native single-line field editing", .serialized)
+@MainActor
+struct SingleLineFieldEditingTests {
+    @Test func nativeEditorKeepsTheCaretAndDefersMarkedTextNormalization() throws {
+        let field = NSTextField()
+        let window = NSWindow(
+            contentRect: NSRect(x: 0, y: 0, width: 400, height: 100), styleMask: .borderless,
+            backing: .buffered, defer: false)
+        window.isReleasedWhenClosed = false
+        window.contentView = field
+        defer { window.close() }
+        #expect(window.makeFirstResponder(field))
+        let editor = try #require(field.currentEditor() as? NSTextView)
+        field.stringValue = "中文\r\n\nName"
+        editor.string = field.stringValue
+        editor.setSelectedRange(NSRange(location: 5, length: 0))
+        #expect(SingleLineFieldEditing.normalizedValue(in: field) == "中文 Name")
+        #expect(editor.string == "中文 Name")
+        #expect(editor.selectedRange() == NSRange(location: 3, length: 0))
+        #expect(window.firstResponder === editor)
+        editor.setMarkedText(
+            "拼音", selectedRange: NSRange(location: 2, length: 0), replacementRange: editor.selectedRange())
+        #expect(editor.hasMarkedText())
+        let composing = editor.string
+        #expect(SingleLineFieldEditing.normalizedValue(in: field) == nil)
+        #expect(editor.string == composing)
+        editor.unmarkText()
+        #expect(SingleLineFieldEditing.normalizedValue(in: field) == editor.string)
+    }
+
+    @Test(arguments: ["en", "zh-Hans", "zh-Hant"])
+    func hostFormKeepsPastedAndTypedTextSingleLine(language: String) async throws {
+        let draft = SingleLineHostTestDraft()
+        let hosting = NSHostingView(
+            rootView: SingleLineHostTestForm(draft: draft).environment(\.locale, Locale(identifier: language)))
+        let window = NSWindow(
+            contentRect: NSRect(x: 0, y: 0, width: 520, height: 400), styleMask: .borderless,
+            backing: .buffered, defer: false)
+        window.isReleasedWhenClosed = false
+        window.contentView = hosting
+        defer { window.close() }
+        hosting.layoutSubtreeIfNeeded()
+        try await Task.sleep(for: .milliseconds(100))
+        let field = try #require(findEditableField(in: hosting, value: "fixture.invalid"))
+        #expect(window.makeFirstResponder(field))
+        let editor = try #require(field.currentEditor() as? NSTextView)
+        editor.selectAll(nil)
+        SingleLineFieldEditing.insert("first.example\r\n\nsecond.example", into: editor)
+        try await Task.sleep(for: .milliseconds(100))
+        #expect(draft.host.host == "first.example second.example")
+        #expect(!field.stringValue.contains(where: { $0.isNewline }))
+        #expect(window.firstResponder === editor)
+        editor.selectAll(nil)
+        editor.insertText("2001:db8::1", replacementRange: editor.selectedRange())
+        try await Task.sleep(for: .milliseconds(100))
+        #expect(draft.host.host == "2001:db8::1")
+        editor.doCommand(by: #selector(NSResponder.insertNewlineIgnoringFieldEditor(_:)))
+        try await Task.sleep(for: .milliseconds(100))
+        #expect(!draft.host.host.contains(where: { $0.isNewline }))
+        #expect(!field.stringValue.contains(where: { $0.isNewline }))
+        let originalHeight = field.frame.height
+        let longAddress = String(repeating: "long-host-", count: 80) + ".invalid"
+        editor.selectAll(nil)
+        SingleLineFieldEditing.insert(longAddress, into: editor)
+        try await Task.sleep(for: .milliseconds(100))
+        #expect(draft.host.host == longAddress)
+        #expect(field.frame.height == originalHeight)
+    }
+
+    private func findEditableField(in view: NSView, value: String) -> NSTextField? {
+        if let field = view as? NSTextField, field.isEditable, field.stringValue == value { return field }
+        return view.subviews.lazy.compactMap { findEditableField(in: $0, value: value) }.first
+    }
+
+    @Test func normalizesTheNativeFieldWithoutAnActiveEditor() {
+        let field = NSTextField()
+        field.stringValue = "中文\r\n\n名称"
+        #expect(SingleLineFieldEditing.normalizedValue(in: field) == "中文 名称")
+        #expect(field.stringValue == "中文 名称")
+    }
+
+    @Test func renameCoordinatorWritesTheSameNormalizedValueAsTheField() {
+        var text = "Original"
+        var submitted = false
+        var cancelled = false
+        let coordinator = SidebarInlineRenameField.Coordinator(
+            text: Binding(get: { text }, set: { text = $0 }),
+            onSubmit: { submitted = true }, onCancel: { cancelled = true }
+        )
+        let field = NSTextField()
+        field.stringValue = "New\u{2028}Name"
+        coordinator.controlTextDidChange(Notification(name: NSControl.textDidChangeNotification, object: field))
+        #expect(text == "New Name")
+        #expect(field.stringValue == text)
+        #expect(!submitted)
+        #expect(!cancelled)
+    }
+}
+
+@Observable
+@MainActor
+private final class SingleLineHostTestDraft {
+    var host = TermindDomain.Host(name: "Fixture", host: "fixture.invalid")
+}
+
+private struct SingleLineHostTestForm: View {
+    @Bindable var draft: SingleLineHostTestDraft
+
+    var body: some View {
+        Form { HostConnectionFields(host: $draft.host) }.formStyle(.grouped)
+    }
+}