diff --git a/Packages/ContinuityKit/Sources/Ingest/StemModelStore.swift b/Packages/ContinuityKit/Sources/Ingest/StemModelStore.swift
index c529848..208dfdc 100644
--- a/Packages/ContinuityKit/Sources/Ingest/StemModelStore.swift
+++ b/Packages/ContinuityKit/Sources/Ingest/StemModelStore.swift
@@ -8,18 +8,37 @@ enum StemModelStore {
     static let fileName = "htdemucs_ft_vocals_fp16weights.onnx"
 
     static var directory: URL {
-        let dir = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)[0]
+        // Application Support, not Caches: the OS evicts Caches under storage pressure, and a
+        // silently re-downloaded 158 MB model at play time is both a delay and a memory/network
+        // spike stacked exactly on playback start (see the jetsam RCA). Excluded from backup —
+        // large and re-derivable.
+        var dir = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)[0]
             .appendingPathComponent("StemModel", isDirectory: true)
         try? FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
+        var values = URLResourceValues()
+        values.isExcludedFromBackup = true
+        try? dir.setResourceValues(values)
         return dir
     }
 
+    /// Pre-move location (Caches). Checked once so existing installs don't re-download.
+    private static var legacyURL: URL {
+        FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)[0]
+            .appendingPathComponent("StemModel", isDirectory: true)
+            .appendingPathComponent(fileName)
+    }
+
     static var localURL: URL { directory.appendingPathComponent(fileName) }
     static var isDownloaded: Bool { FileManager.default.fileExists(atPath: localURL.path) }
 
     /// Returns the local model URL, downloading it first if needed.
     static func ensureModel() async throws -> URL {
         if isDownloaded { return localURL }
+        // Migrate a surviving Caches copy instead of re-downloading it.
+        if FileManager.default.fileExists(atPath: legacyURL.path),
+           (try? FileManager.default.moveItem(at: legacyURL, to: localURL)) != nil {
+            return localURL
+        }
         let (temp, response) = try await URLSession.shared.download(from: remoteURL)
         defer { try? FileManager.default.removeItem(at: temp) }
         if let http = response as? HTTPURLResponse, !(200...299).contains(http.statusCode) {