diff --git a/Examples/CLIPlayer/Package.resolved b/Examples/CLIPlayer/Package.resolved
index d396276..b993940 100644
--- a/Examples/CLIPlayer/Package.resolved
+++ b/Examples/CLIPlayer/Package.resolved
@@ -1,5 +1,5 @@
 {
-  "originHash" : "ae9debf913fe343bc1666f96bbfff92a2bc75d092ebfe274da35849a3886bb29",
+  "originHash" : "7f004e306b3114688e11b6ff9728b35b13f3654fa9c306691fe145020ab90ab1",
   "pins" : [
     {
       "identity" : "flac-binary-xcframework",
@@ -18,6 +18,15 @@
         "revision" : "c0e822e18738ad913864e98d9614927ac1e9337c",
         "version" : "0.1.2"
       }
+    },
+    {
+      "identity" : "swift-sodium",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/jedisct1/swift-sodium.git",
+      "state" : {
+        "revision" : "4f9164a0a2c9a6a7ff53a2833d54a5c79c957342",
+        "version" : "0.9.1"
+      }
     }
   ],
   "version" : 3
diff --git a/Examples/CLIPlayer/Package.swift b/Examples/CLIPlayer/Package.swift
index 86e3565..8890d5b 100644
--- a/Examples/CLIPlayer/Package.swift
+++ b/Examples/CLIPlayer/Package.swift
@@ -7,7 +7,7 @@ let package = Package(
         .macOS(.v14)
     ],
     dependencies: [
-        .package(path: "../..")
+        .package(name: "SendspinKit", path: "../..")
     ],
     targets: [
         .executableTarget(
diff --git a/Examples/CLIPlayer/Sources/CLIPlayer/CLIPlayer.swift b/Examples/CLIPlayer/Sources/CLIPlayer/CLIPlayer.swift
index 389a7ab..cf6dba2 100644
--- a/Examples/CLIPlayer/Sources/CLIPlayer/CLIPlayer.swift
+++ b/Examples/CLIPlayer/Sources/CLIPlayer/CLIPlayer.swift
@@ -54,11 +54,12 @@ final class CLIPlayer {
         }
     }()
 
-    private static func playerConfig(volumeMode: VolumeMode) throws -> PlayerConfiguration {
+    private static func playerConfig(volumeMode: VolumeMode, outputPolicy: OutputSampleRatePolicy) throws -> PlayerConfiguration {
         try PlayerConfiguration(
             bufferCapacity: 2_097_152, // 2MB buffer
             supportedFormats: supportedFormats,
-            volumeMode: volumeMode
+            volumeMode: volumeMode,
+            outputSampleRatePolicy: outputPolicy
         )
     }
 
@@ -78,6 +79,7 @@ final class CLIPlayer {
         clientName: String,
         useTUI: Bool = true,
         volumeMode: VolumeMode = .software,
+        outputPolicy: OutputSampleRatePolicy = .preferCurrentOutput,
         enablePairing: Bool = false
     ) async throws {
         // Simple startup banner before TUI takes over
@@ -92,7 +94,7 @@ final class CLIPlayer {
         }
 
         // Create client
-        let config = try Self.playerConfig(volumeMode: volumeMode)
+        let config = try Self.playerConfig(volumeMode: volumeMode, outputPolicy: outputPolicy)
         // Ephemeral demo device: identity and pairing state vanish when the process exits.
         let device = SendspinDevice.ephemeral()
         let pairing: PairingPresentation = enablePairing ? .display : .tokenOnly
@@ -111,7 +113,7 @@ final class CLIPlayer {
         )
         self.client = client
 
-        fputs("[CONFIG] Volume mode: \(volumeMode) pairing=\(enablePairing)\n", stderr)
+        fputs("[CONFIG] Volume mode: \(volumeMode) outputPolicy=\(outputPolicy.rawValue) pairing=\(enablePairing)\n", stderr)
 
         // Start event monitoring
         eventTask = Task {
@@ -449,12 +451,19 @@ final class CLIPlayer {
     /// Listen for incoming server connections (server-initiated path).
     /// Advertises via mDNS and waits for servers to connect.
     @MainActor
-    func listen(port: UInt16, clientName: String, useTUI: Bool = true, volumeMode: VolumeMode = .software, enablePairing: Bool = false) async throws {
+    func listen(
+        port: UInt16,
+        clientName: String,
+        useTUI: Bool = true,
+        volumeMode: VolumeMode = .software,
+        outputPolicy: OutputSampleRatePolicy = .preferCurrentOutput,
+        enablePairing: Bool = false
+    ) async throws {
         print("🎵 Sendspin CLI Player (Listen Mode)")
         print("━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━")
         print("Advertising on port \(port)...")
 
-        let config = try Self.playerConfig(volumeMode: volumeMode)
+        let config = try Self.playerConfig(volumeMode: volumeMode, outputPolicy: outputPolicy)
         // Ephemeral demo device: identity and pairing state vanish when the process exits.
         let device = SendspinDevice.ephemeral()
         let pairing: PairingPresentation = enablePairing ? .display : .tokenOnly
diff --git a/Examples/CLIPlayer/Sources/CLIPlayer/main.swift b/Examples/CLIPlayer/Sources/CLIPlayer/main.swift
index af44358..56999c3 100644
--- a/Examples/CLIPlayer/Sources/CLIPlayer/main.swift
+++ b/Examples/CLIPlayer/Sources/CLIPlayer/main.swift
@@ -12,6 +12,7 @@ var enableTUI = true
 var listenMode = false
 var listenPort: UInt16 = 8928
 var volumeMode: VolumeMode = .software
+var outputPolicy: OutputSampleRatePolicy = .preferCurrentOutput
 var enablePairing = false
 
 var argIndex = 1
@@ -29,6 +30,20 @@ while argIndex < args.count {
             listenPort = port
             argIndex += 1
         }
+    } else if arg == "--output-policy" {
+        guard argIndex + 1 < args.count else {
+            print("--output-policy requires: prefer, preserve, require")
+            exit(1)
+        }
+        argIndex += 1
+        switch args[argIndex] {
+        case "prefer": outputPolicy = .preferCurrentOutput
+        case "preserve": outputPolicy = .preserveFormatOrder
+        case "require": outputPolicy = .requireCurrentOutput
+        default:
+            print("Unknown output policy '\(args[argIndex])'. Use: prefer, preserve, require")
+            exit(1)
+        }
     } else if arg == "--volume-mode" {
         if argIndex + 1 < args.count {
             argIndex += 1
@@ -92,7 +107,7 @@ sigintSource.resume()
 do {
     if listenMode {
         // Server-initiated: advertise via mDNS and wait for servers to connect
-        try await player.listen(port: listenPort, clientName: clientName, useTUI: enableTUI, enablePairing: enablePairing)
+        try await player.listen(port: listenPort, clientName: clientName, useTUI: enableTUI, outputPolicy: outputPolicy, enablePairing: enablePairing)
     } else {
         // Client-initiated: discover or connect to provided server URL
         if serverURL == nil {
@@ -120,7 +135,14 @@ do {
             print("No server URL available")
             exit(1)
         }
-        try await player.run(serverURL: url, clientName: clientName, useTUI: enableTUI, volumeMode: volumeMode, enablePairing: enablePairing)
+        try await player.run(
+            serverURL: url,
+            clientName: clientName,
+            useTUI: enableTUI,
+            volumeMode: volumeMode,
+            outputPolicy: outputPolicy,
+            enablePairing: enablePairing
+        )
     }
 } catch {
     print("Fatal error: \(error)")
diff --git a/Examples/ClockSyncDiagnostics/Package.swift b/Examples/ClockSyncDiagnostics/Package.swift
index 6b91d7c..c9395f2 100644
--- a/Examples/ClockSyncDiagnostics/Package.swift
+++ b/Examples/ClockSyncDiagnostics/Package.swift
@@ -5,7 +5,7 @@ let package = Package(
     name: "ClockSyncDiagnostics",
     platforms: [.macOS(.v14)],
     dependencies: [
-        .package(path: "../.."),
+        .package(name: "SendspinKit", path: "../.."),
         .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.5.0")
     ],
     targets: [
diff --git a/Examples/ControllerClient/Package.swift b/Examples/ControllerClient/Package.swift
index 61b10f8..713c811 100644
--- a/Examples/ControllerClient/Package.swift
+++ b/Examples/ControllerClient/Package.swift
@@ -5,7 +5,7 @@ let package = Package(
     name: "ControllerClient",
     platforms: [.macOS(.v14)],
     dependencies: [
-        .package(path: "../.."),
+        .package(name: "SendspinKit", path: "../.."),
         .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.5.0")
     ],
     targets: [
diff --git a/Examples/DiscoveryExample/Package.swift b/Examples/DiscoveryExample/Package.swift
index 788d88d..8ff66dd 100644
--- a/Examples/DiscoveryExample/Package.swift
+++ b/Examples/DiscoveryExample/Package.swift
@@ -5,7 +5,7 @@ let package = Package(
     name: "DiscoveryExample",
     platforms: [.macOS(.v14)],
     dependencies: [
-        .package(path: "../.."),
+        .package(name: "SendspinKit", path: "../.."),
         .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.5.0")
     ],
     targets: [
diff --git a/Examples/ErrorRecovery/Package.swift b/Examples/ErrorRecovery/Package.swift
index 06e7b32..5348aa4 100644
--- a/Examples/ErrorRecovery/Package.swift
+++ b/Examples/ErrorRecovery/Package.swift
@@ -5,7 +5,7 @@ let package = Package(
     name: "ErrorRecovery",
     platforms: [.macOS(.v14)],
     dependencies: [
-        .package(path: "../.."),
+        .package(name: "SendspinKit", path: "../.."),
         .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.5.0")
     ],
     targets: [
diff --git a/Examples/MetadataClient/Package.swift b/Examples/MetadataClient/Package.swift
index 816dba4..4651d78 100644
--- a/Examples/MetadataClient/Package.swift
+++ b/Examples/MetadataClient/Package.swift
@@ -5,7 +5,7 @@ let package = Package(
     name: "MetadataClient",
     platforms: [.macOS(.v14)],
     dependencies: [
-        .package(path: "../.."),
+        .package(name: "SendspinKit", path: "../.."),
         .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.5.0")
     ],
     targets: [
diff --git a/Examples/MultiCodecPlayer/Package.swift b/Examples/MultiCodecPlayer/Package.swift
index 56fb778..98b6160 100644
--- a/Examples/MultiCodecPlayer/Package.swift
+++ b/Examples/MultiCodecPlayer/Package.swift
@@ -5,7 +5,7 @@ let package = Package(
     name: "MultiCodecPlayer",
     platforms: [.macOS(.v14)],
     dependencies: [
-        .package(path: "../.."),
+        .package(name: "SendspinKit", path: "../.."),
         .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.5.0")
     ],
     targets: [
diff --git a/Examples/VisualizerClient/Package.swift b/Examples/VisualizerClient/Package.swift
index a1416ac..16d67f0 100644
--- a/Examples/VisualizerClient/Package.swift
+++ b/Examples/VisualizerClient/Package.swift
@@ -5,7 +5,7 @@ let package = Package(
     name: "VisualizerClient",
     platforms: [.macOS(.v14)],
     dependencies: [
-        .package(path: "../..")
+        .package(name: "SendspinKit", path: "../..")
     ],
     targets: [
         .target(
diff --git a/Sources/SendspinKit/Audio/AudioEngine.swift b/Sources/SendspinKit/Audio/AudioEngine.swift
index a95d67c..3a97731 100644
--- a/Sources/SendspinKit/Audio/AudioEngine.swift
+++ b/Sources/SendspinKit/Audio/AudioEngine.swift
@@ -15,6 +15,8 @@ actor AudioEngine {
     private let output: any AudioOutput
     private let audioScheduler: AudioScheduler
     private let clock: any ClockSyncProtocol
+    private var lastWireChunkTimestamp: Int64?
+    private var formatChangeLastWireTimestamp: Int64?
 
     // Command ingress
     private let _commandsSink: DataPlaneSink
@@ -853,12 +855,28 @@ actor AudioEngine {
         Self.rebase(&startupReleaseDeferredChunks, from: oldDelayUs, to: newDelayUs)
     }
 
+    private func recordWireChunkTimestamp(_ timestamp: Int64) async {
+        if let oldTimestamp = formatChangeLastWireTimestamp {
+            let serverNow = await clock.localTimeToServer(MonotonicClock.absoluteMicroseconds())
+            Log.audio.debug(
+                """
+                Format-change first chunk: lastOld=\(oldTimestamp, privacy: .public) \
+                firstNew=\(timestamp, privacy: .public) delta=\(timestamp - oldTimestamp, privacy: .public) \
+                serverNow=\(serverNow, privacy: .public)
+                """
+            )
+            formatChangeLastWireTimestamp = nil
+        }
+        lastWireChunkTimestamp = timestamp
+    }
+
     /// Schedule a chunk for playback.
     private func applyChunk(data: Data, ts: Int64, generation: UInt64?, routeEpoch: UInt64? = nil) async {
         if let generation, generation < streamGeneration {
             return
         }
 
+        await recordWireChunkTimestamp(ts)
         let chunkGeneration = generation ?? streamGeneration
         guard failedDecoderGeneration != chunkGeneration else { return }
         do {
@@ -1167,6 +1185,13 @@ actor AudioEngine {
 
     /// Discard the old output immediately when a route change invalidates its PCM.
     private func applyRouteInvalidatedFormatChange(format: AudioFormatSpec, codecHeader: Data?) async {
+        if let oldTimestamp = lastWireChunkTimestamp {
+            formatChangeLastWireTimestamp = oldTimestamp
+            let serverNow = await clock.localTimeToServer(MonotonicClock.absoluteMicroseconds())
+            Log.audio.debug(
+                "Route-invalidated format-change announcement: lastOld=\(oldTimestamp, privacy: .public) serverNow=\(serverNow, privacy: .public)"
+            )
+        }
         cancelStartupDeadline()
         startupBuffer = nil
         startupFormat = nil
@@ -1204,6 +1229,11 @@ actor AudioEngine {
             await applyStreamStart(format: format, codecHeader: codecHeader)
             return
         }
+        if let oldTimestamp = lastWireChunkTimestamp {
+            formatChangeLastWireTimestamp = oldTimestamp
+            let serverNow = await clock.localTimeToServer(MonotonicClock.absoluteMicroseconds())
+            Log.audio.debug("Format-change announcement: lastOld=\(oldTimestamp, privacy: .public) serverNow=\(serverNow, privacy: .public)")
+        }
         streamGeneration = generation
         formatBoundaries[generation] = FormatBoundary(format: format, codecHeader: codecHeader, startGeneration: startGeneration)
         chunkTimingFormat = format
diff --git a/Sources/SendspinKit/Audio/AudioPlayer.swift b/Sources/SendspinKit/Audio/AudioPlayer.swift
index 082f10e..0d86863 100644
--- a/Sources/SendspinKit/Audio/AudioPlayer.swift
+++ b/Sources/SendspinKit/Audio/AudioPlayer.swift
@@ -856,6 +856,18 @@ actor AudioPlayer {
         let padFrames: Int64
         if let localPlayTime {
             let gapUs = localPlayTime - nowAbsolute - pipelineDelayUs
+            if gapUs < 0 {
+                let ringBacklogFrames = state.pcmRingBuffer.availableToRead / state.frameSize
+                Log.audio
+                    .debug(
+                        """
+                        First-frame negative gap: localLead=\(localPlayTime - nowAbsolute, privacy: .public) \
+                        pipelineDelayUs=\(pipelineDelayUs, privacy: .public) \
+                        framesInFlight=\(framesInFlight, privacy: .public) \
+                        ringBacklogFrames=\(ringBacklogFrames, privacy: .public)
+                        """
+                    )
+            }
             state.startupLateUs = max(0, -gapUs)
             padFrames = min(
                 max(gapUs * sampleRate / 1_000_000, 0),
diff --git a/scripts/set-output-rate.swift b/scripts/set-output-rate.swift
new file mode 100644
index 0000000..a6656cc
--- /dev/null
+++ b/scripts/set-output-rate.swift
@@ -0,0 +1,80 @@
+#!/usr/bin/env swift
+// ABOUTME: Changes the default output device's nominal sample rate for route-change tests.
+// ABOUTME: Validates supported rates and prints the previous rate for restoration.
+
+import CoreAudio
+import Foundation
+
+struct RateError: Error, CustomStringConvertible {
+    let description: String
+}
+
+func check(_ status: OSStatus, _ operation: String) throws {
+    guard status == noErr else {
+        throw RateError(description: "\(operation) failed: OSStatus \(status)")
+    }
+}
+
+func address(_ selector: AudioObjectPropertySelector) -> AudioObjectPropertyAddress {
+    AudioObjectPropertyAddress(
+        mSelector: selector,
+        mScope: kAudioObjectPropertyScopeGlobal,
+        mElement: kAudioObjectPropertyElementMain
+    )
+}
+
+func readRate(_ device: AudioDeviceID) throws -> Float64 {
+    var property = address(kAudioDevicePropertyNominalSampleRate)
+    var rate: Float64 = 0
+    var size = UInt32(MemoryLayout<Float64>.size)
+    try check(AudioObjectGetPropertyData(device, &property, 0, nil, &size, &rate), "Read nominal rate")
+    return rate
+}
+
+do {
+    guard CommandLine.arguments.count == 2,
+          let requested = Float64(CommandLine.arguments[1]), requested.isFinite, requested > 0
+    else {
+        throw RateError(description: "Usage: set-output-rate.swift <hz>")
+    }
+    var defaultOutput = address(kAudioHardwarePropertyDefaultOutputDevice)
+    var device = AudioDeviceID(kAudioObjectUnknown)
+    var size = UInt32(MemoryLayout<AudioDeviceID>.size)
+    try check(
+        AudioObjectGetPropertyData(AudioObjectID(kAudioObjectSystemObject), &defaultOutput, 0, nil, &size, &device),
+        "Resolve default output"
+    )
+    guard device != kAudioObjectUnknown else { throw RateError(description: "No default output device") }
+    let previous = try readRate(device)
+    var available = address(kAudioDevicePropertyAvailableNominalSampleRates)
+    var rangesSize: UInt32 = 0
+    try check(AudioObjectGetPropertyDataSize(device, &available, 0, nil, &rangesSize), "Read supported rates size")
+    var ranges = [AudioValueRange](
+        repeating: AudioValueRange(mMinimum: 0, mMaximum: 0),
+        count: Int(rangesSize) / MemoryLayout<AudioValueRange>.stride
+    )
+    try ranges.withUnsafeMutableBytes { bytes in
+        guard let base = bytes.baseAddress else { throw RateError(description: "No supported rates reported") }
+        try check(AudioObjectGetPropertyData(device, &available, 0, nil, &rangesSize, base), "Read supported rates")
+    }
+    guard ranges.contains(where: { requested >= $0.mMinimum && requested <= $0.mMaximum }) else {
+        let supported = ranges.map { "\($0.mMinimum)...\($0.mMaximum)" }.joined(separator: ", ")
+        throw RateError(description: "Requested rate \(requested) is unsupported; previous=\(previous); supported=\(supported)")
+    }
+    var nominal = address(kAudioDevicePropertyNominalSampleRate)
+    var rate = requested
+    try check(AudioObjectSetPropertyData(device, &nominal, 0, nil, UInt32(MemoryLayout<Float64>.size), &rate), "Set nominal rate")
+    let deadline = ProcessInfo.processInfo.systemUptime + 2
+    var observed = try readRate(device)
+    while observed != requested, ProcessInfo.processInfo.systemUptime < deadline {
+        Thread.sleep(forTimeInterval: 0.01)
+        observed = try readRate(device)
+    }
+    guard observed == requested else {
+        throw RateError(description: "Rate readback timed out: previous=\(previous) requested=\(requested) observed=\(observed)")
+    }
+    print("previous=\(previous) new=\(observed) device=\(device)")
+} catch {
+    fputs("\(error)\n", stderr)
+    exit(1)
+}