Add song project serialization tests

Tests/MusicAssistantCoreTests/SongProjectModelTests.swift

@@ -1,3 +1,4 @@
+import Foundation
 import MusicAssistantCore
 import XCTest
 
@@ -365,4 +366,108 @@ final class SongProjectModelTests: XCTestCase {
         XCTAssertNil(project.emotionalArcPoint(for: "arc-chorus"))
         XCTAssertNil(project.productionDirection(for: "prod-verse"))
     }
+
+    func testSongProjectRoundTripsThroughJSONSerialization() throws {
+        let createdAt = Date(timeIntervalSince1970: 1_700_000_000)
+        let updatedAt = Date(timeIntervalSince1970: 1_700_000_120)
+        let generatedAt = Date(timeIntervalSince1970: 1_700_000_240)
+        let section = SongSection(
+            id: "verse",
+            type: .verse,
+            title: "Verse",
+            order: 0,
+            startTime: 8,
+            endTime: 38,
+            lyrics: "Draft verse",
+            emotion: "reflective",
+            energy: 4,
+            vocalDirection: "close vocal",
+            productionDirection: "subtle pad"
+        )
+        let instrument = InstrumentTrack(
+            instrumentId: "oud",
+            selected: true,
+            variant: "Arabic oud",
+            playingStyle: "picked",
+            role: "lead motif",
+            autoArrangementEnabled: false,
+            placements: [
+                InstrumentPlacement(
+                    sectionId: section.id,
+                    startTime: section.startTime,
+                    endTime: section.endTime,
+                    direction: "answer the vocal"
+                )
+            ]
+        )
+        var project = SongProject(
+            id: "serialized-project",
+            title: "Serializable Song",
+            idea: "A multilingual cinematic song",
+            duration: SongDuration(seconds: 210, description: "about three and a half minutes"),
+            conversationMode: .discuss,
+            languages: [LanguageSelection(id: "arabic", name: "Arabic")],
+            dialects: [DialectSelection(id: "levantine", name: "Levantine", languageID: "arabic")],
+            arabicPronunciationSettings: ArabicPronunciationSettings(
+                isEnabled: true,
+                diacritizationPolicy: .pronunciationTargeted,
+                tanweenPolicy: .preserveUserInput,
+                userNotes: "Keep dialect phrasing natural",
+                preservedSpellings: ["habibi"]
+            ),
+            genres: [GenreStyle(id: "cinematic-pop", name: "Cinematic Pop", aliases: ["orchestral pop"])],
+            moods: [MoodTag(id: "yearning", name: "Yearning")],
+            emotionalArc: [
+                EmotionalArcPoint(
+                    id: "arc-verse",
+                    sectionID: section.id,
+                    emotion: "reflective",
+                    energy: 4,
+                    direction: "slowly opening"
+                )
+            ],
+            bpm: ManualAutoValue(mode: .manual, value: 92),
+            key: ManualAutoValue(mode: .manual, value: "D"),
+            scale: ManualAutoValue(mode: .auto),
+            maqam: ManualAutoValue(mode: .manual, value: "Hijaz"),
+            sections: [section],
+            instruments: [instrument],
+            vocalists: [
+                Vocalist(
+                    id: "lead",
+                    label: "Lead",
+                    voiceType: "tenor",
+                    genderSelection: "male",
+                    performanceStyle: "sung",
+                    assignedSections: [section.id]
+                )
+            ],
+            lyrics: Lyrics(text: "Full lyric draft", sectionTexts: [section.id: "Draft verse"]),
+            productionDirections: [
+                ProductionDirection(id: "prod-verse", sectionID: section.id, text: "keep percussion sparse")
+            ],
+            sunoOutput: SunoOutput(
+                lyricsText: "Full lyric draft",
+                stylePrompt: "Cinematic pop with oud",
+                additionalFields: ["style": "cinematic"],
+                generatedAt: generatedAt
+            ),
+            createdAt: createdAt,
+            updatedAt: updatedAt
+        )
+        project.versions = [
+            SongVersion(
+                id: "version-1",
+                label: "Initial approved direction",
+                snapshot: SongProjectSnapshot(project: project),
+                createdAt: updatedAt
+            )
+        ]
+
+        let encoder = JSONEncoder()
+        let data = try encoder.encode(project)
+        let decodedProject = try JSONDecoder().decode(SongProject.self, from: data)
+
+        XCTAssertEqual(decodedProject, project)
+    }
 }

docs/TASKS.md

@@ -28,7 +28,7 @@ requirement is missing and blocks implementation, record it in
 -   [x] Model language/dialect and Arabic pronunciation settings.
 -   [x] Model BPM, key, scale and maqam with Manual/Auto state.
 -   [x] Model emotional arc and production directions.
--   [ ] Add serialization tests.
+-   [x] Add serialization tests.
 
 ## Phase 2 --- Project Persistence & Versions