Add instrument checkbox selection

Sources/MusicAssistantApp/Presentation/InstrumentBrowserView.swift

@@ -2,6 +2,7 @@ import MusicAssistantCore
 import SwiftUI
 
 struct InstrumentBrowserView: View {
+    @Binding private var project: SongProject
     private let catalog: LocalInstrumentCatalog
 
     @State private var searchText = ""
@@ -9,7 +10,11 @@ struct InstrumentBrowserView: View {
     @State private var selectedRegionOrigin: String?
     @Environment(\.dismiss) private var dismiss
 
-    init(catalog: LocalInstrumentCatalog = LocalInstrumentCatalog()) {
+    init(
+        project: Binding<SongProject>,
+        catalog: LocalInstrumentCatalog = LocalInstrumentCatalog()
+    ) {
+        _project = project
         self.catalog = catalog
     }
 
@@ -50,6 +55,7 @@ struct InstrumentBrowserView: View {
                     ),
                     id: \.id
                 ) { instrument in
+                    Toggle(isOn: selectionBinding(for: instrument)) {
                         VStack(alignment: .leading, spacing: 4) {
                             Text(instrument.name)
                                 .font(.body.weight(.medium))
@@ -65,6 +71,8 @@ struct InstrumentBrowserView: View {
                             .foregroundStyle(.secondary)
                             .lineLimit(1)
                         }
+                    }
+                    .toggleStyle(.checkbox)
                     .padding(.vertical, 2)
                 }
             }
@@ -80,8 +88,31 @@ struct InstrumentBrowserView: View {
         }
         .frame(minWidth: 460, minHeight: 520)
     }
+
+    private func selectionBinding(for instrument: InstrumentCatalogItem) -> Binding<Bool> {
+        Binding {
+            project.isInstrumentSelected(id: instrument.id)
+        } set: { isSelected in
+            project.setInstrumentSelected(
+                id: instrument.id,
+                isSelected: isSelected,
+                variant: instrument.name
+            )
+        }
+    }
 }
 
 #Preview {
-    InstrumentBrowserView()
+    InstrumentBrowserPreview()
+}
+
+private struct InstrumentBrowserPreview: View {
+    @State private var project = SongProject(
+        title: "Instrument Browser Preview",
+        idea: "Browse the instrument catalog."
+    )
+
+    var body: some View {
+        InstrumentBrowserView(project: $project)
+    }
 }

Sources/MusicAssistantApp/Presentation/ProjectInspectorView.swift

@@ -146,7 +146,7 @@ struct ProjectInspectorView: View {
         }
         .background(Color(nsColor: .windowBackgroundColor))
         .sheet(isPresented: $isInstrumentBrowserPresented) {
-            InstrumentBrowserView()
+            InstrumentBrowserView(project: $project)
         }
     }
 

Sources/MusicAssistantCore/Domain/SongProject.swift

@@ -312,6 +312,33 @@ public extension SongProject {
         instruments[index].selected = false
     }
 
+    mutating func setInstrumentSelected(
+        id instrumentId: String,
+        isSelected: Bool,
+        variant: String? = nil
+    ) {
+        guard isSelected else {
+            deselectInstrument(id: instrumentId)
+            return
+        }
+
+        if let index = instruments.firstIndex(where: { $0.instrumentId == instrumentId }) {
+            instruments[index].selected = true
+
+            if instruments[index].variant == nil {
+                instruments[index].variant = variant
+            }
+        } else {
+            instruments.append(
+                InstrumentTrack(
+                    instrumentId: instrumentId,
+                    selected: true,
+                    variant: variant
+                )
+            )
+        }
+    }
+
     mutating func configureInstrument(
         id instrumentId: String,
         variant: String?,

Tests/MusicAssistantCoreTests/SongProjectModelTests.swift

@@ -281,6 +281,40 @@ final class SongProjectModelTests: XCTestCase {
         XCTAssertEqual(project.instrumentTrack(for: "oud")?.placements, [introPlacement])
     }
 
+    func testCatalogSelectionCanBeToggledWithoutReplacingExistingArrangement() {
+        let oudPlacement = InstrumentPlacement(sectionId: "intro", direction: "Opening melody")
+        var project = SongProject(
+            id: "catalog-selection-project",
+            title: "Catalog Selection",
+            idea: "Select and deselect instruments",
+            instruments: [
+                InstrumentTrack(
+                    instrumentId: "oud",
+                    selected: false,
+                    variant: "Arabic oud",
+                    playingStyle: "tremolo",
+                    role: "main hook",
+                    autoArrangementEnabled: false,
+                    placements: [oudPlacement]
+                )
+            ]
+        )
+
+        project.setInstrumentSelected(id: "oud", isSelected: true, variant: "Oud")
+
+        XCTAssertTrue(project.isInstrumentSelected(id: "oud"))
+        XCTAssertEqual(project.instrumentTrack(for: "oud")?.variant, "Arabic oud")
+        XCTAssertEqual(project.instrumentTrack(for: "oud")?.role, "main hook")
+        XCTAssertEqual(project.instrumentTrack(for: "oud")?.placements, [oudPlacement])
+
+        project.setInstrumentSelected(id: "oud", isSelected: false)
+        project.setInstrumentSelected(id: "violin", isSelected: true, variant: "Violin")
+
+        XCTAssertFalse(project.isInstrumentSelected(id: "oud"))
+        XCTAssertTrue(project.isInstrumentSelected(id: "violin"))
+        XCTAssertEqual(project.instrumentTrack(for: "violin")?.variant, "Violin")
+    }
+
     func testMultipleVocalistsCanBeAssignedToSections() {
         var project = SongProject(
             id: "project-6",

docs/TASKS.md

@@ -85,7 +85,7 @@ requirement is missing and blocks implementation, record it in
 -   [x] Build searchable instrument browser.
 -   [x] Add browsing/filtering by family/category.
 -   [x] Add browsing/filtering by region/origin where useful.
--   [ ] Add checkbox-based multi-select and deselect behavior.
+-   [x] Add checkbox-based multi-select and deselect behavior.
 -   [ ] Persist selected instruments on the current Song Project.
 -   [ ] Make selected instruments available to OpenAI/song-generation
     logic for arrangement, roles, entry/exit timing, relevant structure