From f5dfec00a33d4906e5bcc352447a7e9bbf372f60 Mon Sep 17 00:00:00 2001
From: John Burwell <john@b-wells.us>
Date: Tue, 2 Jun 2026 19:22:32 -0500
Subject: [PATCH] Handle duplicate Java collection snapshots

---
 .../Models/Content/LibraryIndex.swift         |  2 +-
 .../Persistence/SourceRestoration.swift       | 16 +++---
 .../World_Manager_for_MinecraftTests.swift    | 54 +++++++++++++++++++
 3 files changed, 62 insertions(+), 10 deletions(-)

diff --git a/World Manager for Minecraft/Models/Content/LibraryIndex.swift b/World Manager for Minecraft/Models/Content/LibraryIndex.swift
index 938b534..4e3c035 100644
--- a/World Manager for Minecraft/Models/Content/LibraryIndex.swift	
+++ b/World Manager for Minecraft/Models/Content/LibraryIndex.swift	
@@ -152,7 +152,7 @@ nonisolated struct CollectionSnapshot: Identifiable, Hashable, Sendable, Codable
     let childDirectoryCount: Int
     let fingerprint: String
 
-    var id: String { folderName }
+    var id: String { "\(folderName)::\(fingerprint)" }
 }
 
 nonisolated struct SourceSnapshot: Hashable, Sendable, Codable {
diff --git a/World Manager for Minecraft/Services/Sources/Persistence/SourceRestoration.swift b/World Manager for Minecraft/Services/Sources/Persistence/SourceRestoration.swift
index 4c15cec..85e95a9 100644
--- a/World Manager for Minecraft/Services/Sources/Persistence/SourceRestoration.swift	
+++ b/World Manager for Minecraft/Services/Sources/Persistence/SourceRestoration.swift	
@@ -214,20 +214,18 @@ enum SourceRestoration {
         _ currentCollections: [CollectionSnapshot],
         persistedCollections: [CollectionSnapshot]
     ) -> Bool {
-        let currentCollectionsByName = Dictionary(
-            uniqueKeysWithValues: currentCollections.map { ($0.folderName, $0) }
-        )
-        let persistedCollectionsByName = Dictionary(
-            uniqueKeysWithValues: persistedCollections.map { ($0.folderName, $0) }
-        )
+        let currentCollectionsByName = Dictionary(grouping: currentCollections, by: \.folderName)
+            .mapValues { $0.map(\.fingerprint).sorted() }
+        let persistedCollectionsByName = Dictionary(grouping: persistedCollections, by: \.folderName)
+            .mapValues { $0.map(\.fingerprint).sorted() }
 
         if currentCollectionsByName.count != persistedCollectionsByName.count {
             return true
         }
 
-        for (folderName, persistedCollection) in persistedCollectionsByName {
-            guard let currentCollection = currentCollectionsByName[folderName],
-                  currentCollection.fingerprint == persistedCollection.fingerprint else {
+        for (folderName, persistedFingerprints) in persistedCollectionsByName {
+            guard let currentFingerprints = currentCollectionsByName[folderName],
+                  currentFingerprints == persistedFingerprints else {
                 return true
             }
         }
diff --git a/World Manager for MinecraftTests/World_Manager_for_MinecraftTests.swift b/World Manager for MinecraftTests/World_Manager_for_MinecraftTests.swift
index 8529272..d7c86d8 100644
--- a/World Manager for MinecraftTests/World_Manager_for_MinecraftTests.swift	
+++ b/World Manager for MinecraftTests/World_Manager_for_MinecraftTests.swift	
@@ -443,6 +443,60 @@ struct World_Manager_for_MinecraftTests {
         #expect(snapshots.map(\.folderName).contains("a/e/f/resourcepacks"))
     }
 
+    @Test func sourceRestorationComparesDuplicateCollectionNamesWithoutCrashing() async throws {
+        let fileManager = FileManager.default
+        let workingURL = fileManager.temporaryDirectory.appendingPathComponent(UUID().uuidString, isDirectory: true)
+        defer { try? fileManager.removeItem(at: workingURL) }
+        try fileManager.createDirectory(at: workingURL, withIntermediateDirectories: true)
+
+        let collectionSnapshots = [
+            CollectionSnapshot(
+                folderName: "mods",
+                modifiedDate: Date(timeIntervalSince1970: 100),
+                childDirectoryCount: 1,
+                fingerprint: "a/b/c/mods::1::100"
+            ),
+            CollectionSnapshot(
+                folderName: "mods",
+                modifiedDate: Date(timeIntervalSince1970: 200),
+                childDirectoryCount: 2,
+                fingerprint: "x/y/z/mods::2::200"
+            )
+        ]
+        var source = MinecraftSource(
+            folderURL: workingURL,
+            origin: .javaLocalFolder(bookmarkData: nil),
+            accessDescriptor: SourceAccessDescriptor(
+                accessorIdentifier: JavaLocalFolderSourceAccess().accessorIdentifier,
+                kind: .localFolder,
+                refreshStrategy: .eagerFullScan
+            ),
+            availability: .available
+        )
+        source.edition = .java
+        source.snapshot = SourceSnapshot(
+            sourceID: workingURL,
+            rootModifiedDate: nil,
+            collectionSnapshots: collectionSnapshots,
+            itemSnapshots: []
+        )
+
+        #expect(SourceRestoration.needsReconcile(source) { _, _ in collectionSnapshots } == false)
+        #expect(
+            SourceRestoration.needsReconcile(source) { _, _ in
+                [
+                    collectionSnapshots[0],
+                    CollectionSnapshot(
+                        folderName: "mods",
+                        modifiedDate: Date(timeIntervalSince1970: 300),
+                        childDirectoryCount: 3,
+                        fingerprint: "x/y/z/mods::3::300"
+                    )
+                ]
+            } == true
+        )
+    }
+
     @Test func sourceLibraryAddSourceCandidatePreservesJavaAggregateProvider() async throws {
         let fileManager = FileManager.default
         let workingURL = fileManager.temporaryDirectory.appendingPathComponent(UUID().uuidString, isDirectory: true)