OOM diagnostics: silence-scan breadcrumbs, unified log subsystem, separation kill switch

Packages/ContinuityKit/Sources/Ingest/MemoryFootprint.swift

@@ -5,6 +5,8 @@ import os
 /// memory allowance remains before the OS kills it — logging it at each pipeline stage turns a
 /// silent jetsam into a console trace that names the eater. Cheap enough to leave in release.
 enum MemoryFootprint {
+    // Same subsystem as the rest of the app's loggers — a split subsystem means a Console
+    // filter on the usual one silently hides every mem[] line.
     private static let logger = Logger(subsystem: "com.continuity.app", category: "mem")
 
     static func breadcrumb(_ label: String) {

Packages/ContinuityKit/Sources/Ingest/PreparationQueue+Stems.swift

@@ -11,6 +11,9 @@ extension PreparationQueue {
     /// **never** separated eagerly — only the neighborhood vocal-aware transitions need next.
     /// Also refreshes the LRU clock and heals links whose files were evicted.
     public func ensureStems(for tracks: [Track], in context: ModelContext) {
+        // Diagnostic kill switch: launch argument `-debug.disableStemSeparation YES` rules the
+        // whole separation pipeline in/out of a memory repro in one run, no code edits.
+        if UserDefaults.standard.bool(forKey: "debug.disableStemSeparation") { return }
         protectedStemKeys = Set(tracks.compactMap(\.youtubeVideoID))
         for track in tracks {
             guard !track.isDemo, track.prepState == .ready,

Packages/ContinuityKit/Sources/Ingest/PreparationQueue.swift

@@ -258,9 +258,11 @@ public final class PreparationQueue {
                     track.durationSeconds = Double(file.length) / file.processingFormat.sampleRate
                 }
                 if needsSilenceScan, track.modelContext != nil {
+                    MemoryFootprint.breadcrumb("silence scan begin")
                     let bounds = await Task.detached(priority: .utility) {
                         SilenceScan.audibleBounds(fileURL: url)
                     }.value
+                    MemoryFootprint.breadcrumb("silence scan end")
                     if let bounds, track.modelContext != nil {
                         track.audibleStartSeconds = bounds.audibleStart
                         track.audibleEndSeconds = bounds.audibleEnd

Packages/ContinuityKit/Sources/Ingest/StemSeparator.swift

@@ -37,7 +37,8 @@ protocol StemSeparating: Sendable {
 /// devices on long tracks (an hour of 44.1 kHz stereo ≈ >1 GB) while the simulator's host RAM
 /// masked it.
 final class OnnxStemSeparator: StemSeparating {
-    private static let log = Logger(subsystem: "com.sanylax.continuity", category: "StemSeparator")
+    // com.continuity.app matches every other logger in the app — one Console filter sees all.
+    private static let log = Logger(subsystem: "com.continuity.app", category: "StemSeparator")
 
     /// Runs one model window: input is planar (1, 2, segment) mix samples; returns the planar
     /// (2, segment) vocals output. Seam so tests can exercise the streaming pipeline without the