diff --git a/Tests/MusicAssistantCoreTests/InstrumentSelectionPersistenceTests.swift b/Tests/MusicAssistantCoreTests/InstrumentSelectionPersistenceTests.swift
new file mode 100644
index 0000000..5f6bc1d
--- /dev/null
+++ b/Tests/MusicAssistantCoreTests/InstrumentSelectionPersistenceTests.swift
@@ -0,0 +1,65 @@
+import Foundation
+import MusicAssistantCore
+import XCTest
+
+final class InstrumentSelectionPersistenceTests: XCTestCase {
+    func testSelectedInstrumentsRoundTripThroughSongProjectSerialization() throws {
+        let section = SongSection(id: "intro", type: .intro, title: "Intro")
+        let project = SongProject(
+            id: "serialized-instrument-selection",
+            title: "Serialized Instrument Selection",
+            idea: "Preserve selected instruments",
+            sections: [section],
+            instruments: [
+                InstrumentTrack(
+                    instrumentId: "oud",
+                    selected: true,
+                    variant: "Arabic Oud",
+                    playingStyle: "tremolo",
+                    role: "lead motif",
+                    autoArrangementEnabled: false,
+                    placements: [InstrumentPlacement(sectionId: section.id, direction: "Opening")]
+                ),
+                InstrumentTrack(
+                    instrumentId: "violin",
+                    selected: false,
+                    variant: "Violin"
+                )
+            ]
+        )
+
+        let encodedProject = try JSONEncoder().encode(project)
+        let decodedProject = try JSONDecoder().decode(SongProject.self, from: encodedProject)
+
+        XCTAssertEqual(decodedProject.instruments, project.instruments)
+        XCTAssertEqual(decodedProject.selectedInstrumentIDs, ["oud"])
+        XCTAssertEqual(decodedProject.instrumentTrack(for: "oud")?.placements.first?.sectionId, section.id)
+    }
+
+    func testSelectedInstrumentsPersistWhenProjectIsSavedAndReopened() async throws {
+        let directoryURL = FileManager.default.temporaryDirectory
+            .appendingPathComponent("music-assistant-instrument-selection-tests")
+            .appendingPathComponent(UUID().uuidString)
+        defer { try? FileManager.default.removeItem(at: directoryURL) }
+
+        let store = LocalSongProjectStore(directoryURL: directoryURL)
+        var project = SongProject(
+            id: "persisted-instrument-selection",
+            title: "Persisted Instrument Selection",
+            idea: "Keep catalog selections"
+        )
+
+        project.setInstrumentSelected(id: "oud", isSelected: true, variant: "Oud")
+        project.setInstrumentSelected(id: "violin", isSelected: true, variant: "Violin")
+        project.setInstrumentSelected(id: "oud", isSelected: false)
+
+        try await store.create(project)
+
+        let reopenedProject = try await store.open(id: project.id)
+
+        XCTAssertFalse(reopenedProject.isInstrumentSelected(id: "oud"))
+        XCTAssertTrue(reopenedProject.isInstrumentSelected(id: "violin"))
+        XCTAssertEqual(reopenedProject.selectedInstrumentIDs, ["violin"])
+        XCTAssertEqual(reopenedProject.instrumentTrack(for: "oud")?.variant, "Oud")
+    }
+}
diff --git a/docs/TASKS.md b/docs/TASKS.md
index 46f1c6e..59a2c43 100644
--- a/docs/TASKS.md
+++ b/docs/TASKS.md
@@ -91,7 +91,7 @@ requirement is missing and blocks implementation, record it in
     logic for arrangement, roles, entry/exit timing, relevant structure
     decisions and Suno Style Prompt generation.
 -   [x] Preserve existing Manual/Auto arrangement behavior.
--   [ ] Add tests for catalog search, category/region filtering,
+-   [x] Add tests for catalog search, category/region filtering,
     selection persistence and SongProject serialization.
 
 ## Phase 7 --- Prompt Compiler