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Store the stem model in Application Support instead of Caches #87

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Merged
sanylax0 merged 1 commit into from
Jul 18, 2026
Merged

Store the stem model in Application Support instead of Caches #87

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21 changes: 20 additions & 1 deletion Packages/ContinuityKit/Sources/Ingest/StemModelStore.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -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) {
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