diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index b4fe4ad..09ada31 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.minamp"
-    android:versionCode="2"
-    android:versionName="1.1"
+    android:versionCode="3"
+    android:versionName="1.2"
     android:installLocation="auto">
 
     <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="10" />
diff --git a/res/layout/activity_setup.xml b/res/layout/activity_setup.xml
index 3fd1abc..b73d354 100644
--- a/res/layout/activity_setup.xml
+++ b/res/layout/activity_setup.xml
@@ -30,6 +30,12 @@
             <Button android:id="@+id/btn_manual" style="@style/ButtonOutline"
                 android:layout_width="match_parent" android:layout_marginTop="10dp"
                 android:text="Connect to a server address" />
+            <TextView android:id="@+id/btn_setup_log"
+                android:layout_width="wrap_content" android:layout_height="wrap_content"
+                android:layout_marginTop="18dp" android:padding="8dp"
+                android:background="@drawable/bg_pressable"
+                android:textColor="@color/text2" android:textSize="12sp"
+                android:text="Connection log" />
         </LinearLayout>
 
         <!-- PIN -->
@@ -40,7 +46,7 @@
             <TextView android:layout_width="wrap_content" android:layout_height="wrap_content"
                 android:gravity="center" android:textColor="@color/text2" android:textSize="13sp"
                 android:paddingTop="12dp"
-                android:text="On a computer or another phone, open" />
+                android:text="On a computer or a newer phone, open" />
             <TextView android:layout_width="wrap_content" android:layout_height="wrap_content"
                 android:text="plex.tv/link" android:textSize="22sp" android:textStyle="bold"
                 android:textColor="@color/accent" android:paddingTop="4dp" />
@@ -60,8 +66,11 @@
                     android:textColor="@color/text2" android:textSize="12sp" android:paddingLeft="8dp"
                     android:text="Waiting for you to link…" />
             </LinearLayout>
+            <Button android:id="@+id/btn_pin_check" style="@style/ButtonAccent"
+                android:layout_width="match_parent" android:layout_marginTop="20dp"
+                android:text="I've entered it \u2014 check now" />
             <Button android:id="@+id/btn_pin_cancel" style="@style/ButtonOutline"
-                android:layout_width="match_parent" android:layout_marginTop="24dp"
+                android:layout_width="match_parent" android:layout_marginTop="10dp"
                 android:text="Cancel" />
         </LinearLayout>
 
diff --git a/src/com/minamp/BaseActivity.java b/src/com/minamp/BaseActivity.java
index 310f33a..5e8ccf1 100644
--- a/src/com/minamp/BaseActivity.java
+++ b/src/com/minamp/BaseActivity.java
@@ -397,6 +397,7 @@ public abstract class BaseActivity extends Activity implements PlayerService.Lis
             "Library: " + app.sectionTitle(),
             "Server: " + (s == null ? "-" : s.name),
             "Connection: " + conn,
+            "Connection log & streaming test",
             "Sign out",
         };
         new AlertDialog.Builder(this)
@@ -424,7 +425,8 @@ public abstract class BaseActivity extends Activity implements PlayerService.Lis
                                 });
                             }
                             break;
-                        case 6: confirmSignOut(); break;
+                        case 6: showDiagnostics(); break;
+                        case 7: confirmSignOut(); break;
                     }
                 }
             }).show();
@@ -432,6 +434,108 @@ public abstract class BaseActivity extends Activity implements PlayerService.Lis
 
     protected void onConnectionChanged() {}
 
+    // ------------------------------------------------------------------ diagnostics
+
+    /** Connection log with "test streaming" and "save to SD card", for reporting problems. */
+    protected void showDiagnostics() {
+        final android.widget.ScrollView sv = new android.widget.ScrollView(this);
+        final TextView tv = new TextView(this);
+        tv.setTextSize(9);
+        tv.setTextColor(0xFFDDDDDD);
+        tv.setTypeface(android.graphics.Typeface.MONOSPACE);
+        int p = Ui.dp(this, 6);
+        tv.setPadding(p, p, p, p);
+        String log = com.minamp.net.DiagLog.dump();
+        tv.setText(log.length() > 0 ? log : "Nothing logged yet.");
+        sv.addView(tv);
+        AlertDialog.Builder b = new AlertDialog.Builder(this)
+            .setTitle("Connection log")
+            .setView(sv)
+            .setNegativeButton("Save to SD card", new DialogInterface.OnClickListener() {
+                public void onClick(DialogInterface d, int w) { saveDiagnostics(); }
+            })
+            .setPositiveButton("Close", null);
+        if (app.library != null) {
+            b.setNeutralButton("Test streaming", new DialogInterface.OnClickListener() {
+                public void onClick(DialogInterface d, int w) { testStreaming(); }
+            });
+        }
+        AlertDialog dlg = b.create();
+        dlg.show();
+        sv.post(new Runnable() { public void run() { sv.fullScroll(View.FOCUS_DOWN); } });
+    }
+
+    private void saveDiagnostics() {
+        try {
+            if (!android.os.Environment.MEDIA_MOUNTED.equals(android.os.Environment.getExternalStorageState())) {
+                toast("No SD card available");
+                return;
+            }
+            java.io.File f = new java.io.File(android.os.Environment.getExternalStorageDirectory(), "Minamp-log.txt");
+            java.io.FileOutputStream o = new java.io.FileOutputStream(f);
+            String head = "Minamp " + com.minamp.plex.Plex.version + " on " + android.os.Build.MODEL
+                + ", Android " + android.os.Build.VERSION.RELEASE + "\n";
+            o.write((head + com.minamp.net.DiagLog.dump()).getBytes("UTF-8"));
+            o.close();
+            toast("Saved as Minamp-log.txt on the SD card");
+        } catch (Exception e) {
+            toast("Couldn't save: " + msg(e));
+        }
+    }
+
+    /** Asks the server about every transcode variant for one track, and logs exactly what it says. */
+    private void testStreaming() {
+        final Library lib = lib();
+        final Item current = PlayQueue.get().current();
+        toast("Testing\u2026 (about 30 s)");
+        run(new Task<Object>() {
+            public Object work() throws Exception {
+                com.minamp.net.DiagLog.log("=== streaming test ===");
+                Item t = current;
+                if (t == null) {
+                    List<Item> r = lib.libraryRadio();
+                    if (r.isEmpty()) throw new Exception("no tracks in the library");
+                    t = r.get(0);
+                }
+                lib.ensureMedia(t);
+                com.minamp.net.DiagLog.log("track: " + t.title + " [" + t.codec + "/" + t.container + " " + t.bitrate + " kbps] via "
+                    + (lib.server.active() == null ? "?" : Server.kindLabel(lib.server.active().kind)));
+                int kbps = app.currentMaxKbps();
+                if (kbps <= 0) kbps = 320;
+                for (int v = 0; v < Library.VARIANTS; v++) {
+                    com.minamp.net.DiagLog.log("variant " + v + " (" + Library.VARIANT_NAMES[v] + ") decision: " + lib.decision(t, kbps, v));
+                    String session = "minamp-test-" + System.currentTimeMillis() + "-" + v;
+                    String url = lib.transcodeUrl(t, kbps, 0, session, v);
+                    com.minamp.net.Http.Response r = null;
+                    try {
+                        r = com.minamp.net.Http.get(url, null, 30000);
+                        if (r.code < 400) {
+                            byte[] buf = new byte[4096];
+                            int n = r.body.read(buf);
+                            boolean mp3 = n > 3 && ((buf[0] == 'I' && buf[1] == 'D' && buf[2] == '3') || ((buf[0] & 0xFF) == 0xFF && (buf[1] & 0xE0) == 0xE0));
+                            com.minamp.net.DiagLog.log("variant " + v + " start: " + r.code + ", " + r.header("content-type")
+                                + ", first bytes " + (mp3 ? "look like MP3" : "are NOT MP3"));
+                        } else {
+                            com.minamp.net.DiagLog.log("variant " + v + " start: " + r.code + " " + com.minamp.plex.Plex.snippet(r.readString()));
+                        }
+                    } catch (Exception e) {
+                        com.minamp.net.DiagLog.log("variant " + v + " start failed: " + com.minamp.net.Threads.describe(e));
+                    } finally {
+                        com.minamp.net.Http.abort(r);
+                        lib.stopTranscode(session);
+                    }
+                }
+                com.minamp.net.DiagLog.log("=== end of test ===");
+                return null;
+            }
+            public void done(Object o) { showDiagnostics(); }
+            public void fail(Exception e) {
+                com.minamp.net.DiagLog.log("streaming test failed: " + msg(e));
+                showDiagnostics();
+            }
+        });
+    }
+
     private static String qualityLabel(int kbps) {
         for (int i = 0; i < App.QUALITIES.length; i++) if (App.QUALITIES[i] == kbps) return App.QUALITY_LABELS[i];
         return kbps + " kbps";
diff --git a/src/com/minamp/PlayerService.java b/src/com/minamp/PlayerService.java
index 92c76e8..f61d8f2 100644
--- a/src/com/minamp/PlayerService.java
+++ b/src/com/minamp/PlayerService.java
@@ -125,6 +125,7 @@ public class PlayerService extends Service implements MediaPlayer.OnPreparedList
     private String routeId;
     private int retries;
     private int[] variantOrder;   // transcode variant behind each URL of the current route
+    private int acceptedVariant = -1;
     private String refusal;       // what the server said when it refused the current stream
     private int refusalCode;
     private int failuresInRow;
@@ -166,6 +167,11 @@ public class PlayerService extends Service implements MediaPlayer.OnPreparedList
                 });
             }
         };
+        File cache = null;
+        try {
+            if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) cache = getExternalCacheDir();
+        } catch (Exception ignored) {}
+        proxy.cacheDir = cache != null ? cache : getCacheDir();
         try { proxy.start(); } catch (IOException e) { /* reported when playback starts */ }
         try {
             TelephonyManager tm = (TelephonyManager) getSystemService(TELEPHONY_SERVICE);
@@ -360,6 +366,8 @@ public class PlayerService extends Service implements MediaPlayer.OnPreparedList
     private void rememberVariantOf(int[] order, int index) {
         if (order == null || index < 0 || index >= order.length) return;
         int v = order[index];
+        if (order == variantOrder) acceptedVariant = v;
+        com.minamp.net.DiagLog.log("server accepted transcode variant " + v + " (" + Library.VARIANT_NAMES[v] + ")");
         if (v != Library.preferredVariant) {
             Library.preferredVariant = v;
             App.get().prefs.edit().putInt("tcVariant", v).commit();
@@ -387,7 +395,9 @@ public class PlayerService extends Service implements MediaPlayer.OnPreparedList
                 routeId = proxy.newId();
                 refusal = null;
                 refusalCode = 0;
-                mp.setDataSource(proxy.register(routeId, urls, ext));
+                acceptedVariant = -1;
+                // transcodes are fetched once and buffered, so player reconnects can't restart them
+                mp.setDataSource(proxy.register(routeId, urls, ext, transcoding));
             }
             setState(BUFFERING, "Buffering…");
             mp.prepareAsync();
@@ -520,7 +530,7 @@ public class PlayerService extends Service implements MediaPlayer.OnPreparedList
         if (track == null) return;
         if (ms < 0) ms = 0;
         if (track.duration > 0 && ms > track.duration - 1000) ms = Math.max(0, track.duration - 1000);
-        if (mp != null && prepared && (!transcoding || fromFile)) {
+        if (mp != null && prepared && (!transcoding || fromFile || proxy.isComplete(routeId))) {
             try { mp.seekTo((int) ms); } catch (Exception ignored) {}
             lastPos = ms;
             notifyListeners();
@@ -551,12 +561,13 @@ public class PlayerService extends Service implements MediaPlayer.OnPreparedList
 
     private void releasePlayer() {
         if (routeId != null) { proxy.unregister(routeId); routeId = null; }
-        if (session != null) {
-            final String s = session;
+        if (session != null && acceptedVariant >= 0) {
+            final String s = Library.variantSession(session, acceptedVariant);
             final App app = App.get();
             reporter.execute(new Runnable() { public void run() { if (app.library != null) app.library.stopTranscode(s); } });
-            session = null;
         }
+        session = null;
+        acceptedVariant = -1;
         if (mp != null) {
             try { mp.reset(); } catch (Exception ignored) {}
             try { mp.release(); } catch (Exception ignored) {}
diff --git a/src/com/minamp/SetupActivity.java b/src/com/minamp/SetupActivity.java
index 9633f76..e3bc8fc 100644
--- a/src/com/minamp/SetupActivity.java
+++ b/src/com/minamp/SetupActivity.java
@@ -47,7 +47,9 @@ public class SetupActivity extends BaseActivity {
 
         findViewById(R.id.btn_signin).setOnClickListener(new View.OnClickListener() { public void onClick(View v) { startPin(); } });
         findViewById(R.id.btn_manual).setOnClickListener(new View.OnClickListener() { public void onClick(View v) { show(manual); } });
-        findViewById(R.id.btn_pin_cancel).setOnClickListener(new View.OnClickListener() { public void onClick(View v) { pinSeq++; show(welcome); } });
+        findViewById(R.id.btn_pin_cancel).setOnClickListener(new View.OnClickListener() { public void onClick(View v) { pinSeq++; clearPendingPin(); show(welcome); } });
+        findViewById(R.id.btn_pin_check).setOnClickListener(new View.OnClickListener() { public void onClick(View v) { checkPinNow(pinSeq); } });
+        findViewById(R.id.btn_setup_log).setOnClickListener(new View.OnClickListener() { public void onClick(View v) { showDiagnostics(); } });
         findViewById(R.id.btn_manual_back).setOnClickListener(new View.OnClickListener() { public void onClick(View v) { show(welcome); } });
         findViewById(R.id.btn_manual_go).setOnClickListener(new View.OnClickListener() { public void onClick(View v) { connectManual(); } });
         findViewById(R.id.btn_choose_back).setOnClickListener(new View.OnClickListener() {
@@ -60,7 +62,7 @@ public class SetupActivity extends BaseActivity {
             loadSections(app.server, null);
         } else if (mode == MODE_SERVER && account != null) {
             loadServers(account);
-        } else {
+        } else if (!resumePendingPin()) {
             show(welcome);
         }
     }
@@ -96,21 +98,21 @@ public class SetupActivity extends BaseActivity {
 
     // ------------------------------------------------------------------ PIN sign-in
 
+    private int pinChecks;
+    private boolean pinCheckRunning;
+
     private void startPin() {
-        showBusy("Contacting plex.tv…\n(the first secure connection takes a few seconds on this phone)");
+        clearPendingPin();
+        showBusy("Contacting plex.tv\u2026\n(the first secure connection takes a few seconds on this phone)");
         final int my = ++pinSeq;
         run(new Task<Plex.Pin>() {
             public Plex.Pin work() throws Exception { return Plex.createPin(); }
             public void done(Plex.Pin p) {
                 if (my != pinSeq) return;
-                pinId = p.id;
-                pinStarted = System.currentTimeMillis();
-                StringBuilder spaced = new StringBuilder();
-                for (int i = 0; i < p.code.length(); i++) { if (i > 0) spaced.append(' '); spaced.append(p.code.charAt(i)); }
-                pinCode.setText(spaced.toString());
-                pinStatus.setText("Waiting for you to link…");
-                show(pinPage);
-                pollPin(my);
+                // Remember the code: the phone may close Minamp while you type it in elsewhere.
+                app.prefs.edit().putLong("pinId", p.id).putString("pinCode", p.code)
+                    .putLong("pinStart", System.currentTimeMillis()).commit();
+                showPin(p.id, p.code, System.currentTimeMillis());
             }
             public void fail(Exception e) {
                 if (my != pinSeq) return;
@@ -120,30 +122,84 @@ public class SetupActivity extends BaseActivity {
         });
     }
 
-    private void pollPin(final int my) {
+    /** Resume waiting for a code created earlier (Minamp was closed while the user typed it in). */
+    private boolean resumePendingPin() {
+        long id = app.prefs.getLong("pinId", 0);
+        String code = app.prefs.getString("pinCode", null);
+        long start = app.prefs.getLong("pinStart", 0);
+        if (id == 0 || code == null || System.currentTimeMillis() - start > 14 * 60 * 1000) {
+            clearPendingPin();
+            return false;
+        }
+        com.minamp.net.DiagLog.log("resuming sign-in code " + code);
+        showPin(id, code, start);
+        return true;
+    }
+
+    private void clearPendingPin() {
+        app.prefs.edit().remove("pinId").remove("pinCode").remove("pinStart").commit();
+    }
+
+    private void showPin(long id, String code, long started) {
+        pinId = id;
+        pinStarted = started;
+        pinChecks = 0;
+        StringBuilder spaced = new StringBuilder();
+        for (int i = 0; i < code.length(); i++) { if (i > 0) spaced.append(' '); spaced.append(code.charAt(i)); }
+        pinCode.setText(spaced.toString());
+        pinStatus.setText("Waiting for you to link\u2026");
+        show(pinPage);
+        int my = ++pinSeq;
+        checkPinNow(my);
+    }
+
+    @Override
+    protected void onResume() {
+        super.onResume();
+        // back from typing the code somewhere else: check straight away
+        if (pinPage != null && pinPage.getVisibility() == View.VISIBLE && !pinCheckRunning) checkPinNow(pinSeq);
+    }
+
+    private void schedulePinCheck(final int my) {
         app.handler.postDelayed(new Runnable() {
-            public void run() {
-                if (my != pinSeq || destroyed) return;
-                if (System.currentTimeMillis() - pinStarted > 14 * 60 * 1000) {
-                    pinStatus.setText("Code expired — go back and try again");
+            public void run() { checkPinNow(my); }
+        }, 3000);
+    }
+
+    private void checkPinNow(final int my) {
+        if (my != pinSeq || destroyed || pinCheckRunning) return;
+        long age = System.currentTimeMillis() - pinStarted;
+        if (age > 14 * 60 * 1000) {
+            pinStatus.setText("Code expired \u2014 press Cancel and sign in again");
+            clearPendingPin();
+            return;
+        }
+        pinCheckRunning = true;
+        run(new Task<String>() {
+            public String work() throws Exception { return Plex.checkPin(pinId); }
+            public void done(String token) {
+                pinCheckRunning = false;
+                if (my != pinSeq) return;
+                pinChecks++;
+                if (token == null) {
+                    long left = (14 * 60 * 1000 - (System.currentTimeMillis() - pinStarted)) / 60000;
+                    pinStatus.setText("Not linked yet \u00b7 checked " + pinChecks + "\u00d7 \u00b7 " + left + " min left");
+                    schedulePinCheck(my);
                     return;
                 }
-                SetupActivity.this.run(new Task<String>() {
-                    public String work() throws Exception { return Plex.checkPin(pinId); }
-                    public void done(String token) {
-                        if (my != pinSeq) return;
-                        if (token == null) { pollPin(my); return; }
-                        pinSeq++;
-                        signedIn(token);
-                    }
-                    public void fail(Exception e) {
-                        if (my != pinSeq) return;
-                        pinStatus.setText("Retrying… (" + msg(e) + ")");
-                        pollPin(my);
-                    }
-                });
+                pinStatus.setText("Linked!");
+                pinSeq++;
+                clearPendingPin();
+                signedIn(token);
             }
-        }, 2500);
+            public void fail(Exception e) {
+                pinCheckRunning = false;
+                if (my != pinSeq) return;
+                pinChecks++;
+                pinStatus.setText("Check " + pinChecks + " failed: " + msg(e) + " \u2014 retrying");
+                schedulePinCheck(my);
+            }
+        });
     }
 
     private void signedIn(final String account) {
diff --git a/src/com/minamp/net/DiagLog.java b/src/com/minamp/net/DiagLog.java
new file mode 100644
index 0000000..bd6b30a
--- /dev/null
+++ b/src/com/minamp/net/DiagLog.java
@@ -0,0 +1,47 @@
+package com.minamp.net;
+
+import java.text.SimpleDateFormat;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+import java.util.Locale;
+
+/**
+ * In-memory diagnostics log (last few hundred lines): every request with its status and timing,
+ * sign-in steps, stream attempts. Viewable in the app and savable to the SD card, so a problem
+ * on a real server can be reported precisely. Tokens are never logged.
+ */
+public final class DiagLog {
+    private static final int MAX = 400;
+    private static final List<String> lines = new ArrayList<String>();
+    private static final SimpleDateFormat fmt = new SimpleDateFormat("HH:mm:ss", Locale.US);
+
+    private DiagLog() {}
+
+    public static void log(String msg) {
+        String line;
+        synchronized (fmt) { line = fmt.format(new Date()) + " " + msg; }
+        synchronized (lines) {
+            lines.add(line);
+            if (lines.size() > MAX) lines.remove(0);
+        }
+    }
+
+    public static String dump() {
+        StringBuilder sb = new StringBuilder();
+        synchronized (lines) {
+            for (int i = 0; i < lines.size(); i++) sb.append(lines.get(i)).append('\n');
+        }
+        return sb.toString();
+    }
+
+    public static void clear() {
+        synchronized (lines) { lines.clear(); }
+    }
+
+    /** URL without the token value, safe to show and share. */
+    public static String redact(String url) {
+        if (url == null) return "";
+        return url.replaceAll("(X-Plex-Token=)[^&]*", "$1***");
+    }
+}
diff --git a/src/com/minamp/net/Http.java b/src/com/minamp/net/Http.java
index fed0365..6f0e5fc 100644
--- a/src/com/minamp/net/Http.java
+++ b/src/com/minamp/net/Http.java
@@ -283,7 +283,20 @@ public final class Http {
 
     public static Response request(String method, String url, Map<String, String> headers, byte[] body, int timeoutMs) throws IOException {
         for (int redirects = 0; ; redirects++) {
-            Response r = requestOnce(method, url, headers, body, timeoutMs);
+            long t0 = System.currentTimeMillis();
+            Response r;
+            try {
+                r = requestOnce(method, url, headers, body, timeoutMs);
+            } catch (IOException e) {
+                DiagLog.log(method + " " + DiagLog.redact(url) + " -> FAILED after " + (System.currentTimeMillis() - t0) + "ms: " + Threads.describe(e));
+                throw e;
+            } catch (RuntimeException e) {
+                DiagLog.log(method + " " + DiagLog.redact(url) + " -> FAILED: " + Threads.describe(e));
+                throw e;
+            }
+            if (!url.contains("/photo/:/transcode")) { // artwork would drown out everything else
+                DiagLog.log(method + " " + DiagLog.redact(url) + " -> " + r.code + " (" + (System.currentTimeMillis() - t0) + "ms)");
+            }
             if ((r.code == 301 || r.code == 302 || r.code == 307 || r.code == 308) && redirects < 4
                     && ("GET".equals(method) || "HEAD".equals(method))) {
                 String loc = r.header("location");
diff --git a/src/com/minamp/net/StreamProxy.java b/src/com/minamp/net/StreamProxy.java
index aa1c715..e2e0f2d 100644
--- a/src/com/minamp/net/StreamProxy.java
+++ b/src/com/minamp/net/StreamProxy.java
@@ -1,9 +1,12 @@
 package com.minamp.net;
 
 import java.io.BufferedInputStream;
+import java.io.File;
+import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.io.RandomAccessFile;
 import java.net.InetAddress;
 import java.net.ServerSocket;
 import java.net.Socket;
@@ -17,8 +20,13 @@ import java.util.Map;
 /**
  * Loopback HTTP server that hands the platform MediaPlayer a plain http://127.0.0.1 URL and
  * fetches the real stream through {@link Http} (our own TLS, plex.direct, relay...).
- * It also turns chunked transcoder output into a simple read-until-close response, which
- * Android 2.x's media stack copes with much better.
+ *
+ * Two kinds of route:
+ *  - pass-through (original files): each player request, Range included, is forwarded.
+ *  - buffered (transcodes): the server is asked exactly once; the bytes go to a temp file and
+ *    every player request (reconnects included) is served from it. Asking Plex's transcoder
+ *    twice for one session tears the first down, which shows up as 503s and cut-off tracks.
+ * Each route may carry several alternative URLs; the first the server accepts wins.
  */
 public final class StreamProxy implements Runnable {
 
@@ -27,14 +35,8 @@ public final class StreamProxy implements Runnable {
     private volatile boolean running;
     private int counter;
     private final Map<String, Route> routes = new HashMap<String, Route>();
-
-    /** One stream, with fallback URLs tried in order until the server accepts one. */
-    private static final class Route {
-        final List<String> urls;
-        int chosen = -1; // index that worked; later requests (seeks) go straight to it
-        Route(List<String> urls) { this.urls = urls; }
-    }
-    private final Map<String, List<Http.Response>> live = new HashMap<String, List<Http.Response>>();
+    /** Where buffered streams are written (set by the app; temp dir otherwise). */
+    public volatile File cacheDir;
 
     public interface Listener {
         /** Every URL was refused (or the proxy failed); code is the last HTTP status, or 0. */
@@ -44,6 +46,25 @@ public final class StreamProxy implements Runnable {
     }
     public volatile Listener listener;
 
+    private static final class Route {
+        final String id;
+        final List<String> urls;
+        final boolean buffered;
+        int chosen = -1;                       // index that worked
+        final List<Http.Response> live = new ArrayList<Http.Response>();
+        // buffered state (guarded by this)
+        boolean started, done, cancelled;
+        long written;
+        int failCode;
+        String failMessage;
+        File file;
+        Http.Response upstream;
+
+        Route(String id, List<String> urls, boolean buffered) {
+            this.id = id; this.urls = urls; this.buffered = buffered;
+        }
+    }
+
     public synchronized void start() throws IOException {
         if (running) return;
         server = new ServerSocket(0, 8, InetAddress.getByName("127.0.0.1"));
@@ -55,45 +76,55 @@ public final class StreamProxy implements Runnable {
     public synchronized void shutdown() {
         running = false;
         try { if (server != null) server.close(); } catch (IOException ignored) {}
-        synchronized (routes) {
-            for (String id : new ArrayList<String>(live.keySet())) abortLocked(id);
-            routes.clear();
-        }
+        List<String> ids;
+        synchronized (routes) { ids = new ArrayList<String>(routes.keySet()); }
+        for (int i = 0; i < ids.size(); i++) unregister(ids.get(i));
     }
 
     public int port() { return server == null ? -1 : server.getLocalPort(); }
 
-    /** @return the local URL to give MediaPlayer, ending in a fake extension it may sniff. */
-    public String register(String id, String remoteUrl, String ext) {
-        List<String> l = new ArrayList<String>();
-        l.add(remoteUrl);
-        return register(id, l, ext);
-    }
-
-    public String register(String id, List<String> remoteUrls, String ext) {
-        synchronized (routes) {
-            routes.put(id, new Route(new ArrayList<String>(remoteUrls)));
-        }
-        return "http://127.0.0.1:" + port() + "/s/" + id + "/stream." + ext;
-    }
-
     public String newId() {
         synchronized (routes) { return Integer.toString(++counter) + "x" + Long.toString(System.currentTimeMillis() % 100000, 36); }
     }
 
-    /** Forget a route and cut any upstream connections still feeding it. */
-    public void unregister(String id) {
-        if (id == null) return;
-        synchronized (routes) {
-            routes.remove(id);
-            abortLocked(id);
-        }
+    public String register(String id, String remoteUrl, String ext) {
+        List<String> l = new ArrayList<String>();
+        l.add(remoteUrl);
+        return register(id, l, ext, false);
     }
 
-    private void abortLocked(String id) {
-        List<Http.Response> l = live.remove(id);
-        if (l == null) return;
-        for (int i = 0; i < l.size(); i++) Http.abort(l.get(i));
+    /** @return the local URL to give MediaPlayer, ending in an extension it may sniff. */
+    public String register(String id, List<String> remoteUrls, String ext, boolean buffered) {
+        synchronized (routes) {
+            routes.put(id, new Route(id, new ArrayList<String>(remoteUrls), buffered));
+        }
+        return "http://127.0.0.1:" + port() + "/s/" + id + "/stream." + ext;
+    }
+
+    /** Forget a route, cut its upstream connections and delete its buffer file. */
+    public void unregister(String id) {
+        if (id == null) return;
+        Route r;
+        synchronized (routes) { r = routes.remove(id); }
+        if (r == null) return;
+        final File f;
+        synchronized (r) {
+            r.cancelled = true;
+            Http.abort(r.upstream);
+            for (int i = 0; i < r.live.size(); i++) Http.abort(r.live.get(i));
+            r.live.clear();
+            r.notifyAll();
+            f = r.file;
+        }
+        if (f != null) {
+            // give readers a moment to notice before the file goes away
+            Threads.start(new Runnable() {
+                public void run() {
+                    try { Thread.sleep(1500); } catch (InterruptedException ignored) {}
+                    f.delete();
+                }
+            }, "proxy-cleanup");
+        }
     }
 
     public void run() {
@@ -111,8 +142,9 @@ public final class StreamProxy implements Runnable {
         }
     }
 
+    // ------------------------------------------------------------------ request handling
+
     private void handle(Socket s) {
-        Http.Response up = null;
         String id = null;
         try {
             s.setSoTimeout(60000);
@@ -129,7 +161,6 @@ public final class StreamProxy implements Runnable {
             String[] parts = reqLine.split(" ");
             String method = parts.length > 0 ? parts[0] : "GET";
             String path = parts.length > 1 ? parts[1] : "/";
-            // /s/<id>/stream.mp3
             if (path.startsWith("/s/")) {
                 int slash = path.indexOf('/', 3);
                 id = slash < 0 ? path.substring(3) : path.substring(3, slash);
@@ -137,58 +168,88 @@ public final class StreamProxy implements Runnable {
             Route route;
             synchronized (routes) { route = id == null ? null : routes.get(id); }
             if (route == null) {
-                out.write("HTTP/1.0 404 Not Found\r\nContent-Length: 0\r\nConnection: close\r\n\r\n".getBytes("ISO-8859-1"));
-                out.flush();
+                writeEmpty(out, 404, "Not Found");
                 return;
             }
-
-            Map<String, String> h = new LinkedHashMap<String, String>();
-            h.put("Accept", "*/*");
-            String range = reqHeaders.get("range");
-            if (range != null) h.put("Range", range);
             boolean head = "HEAD".equals(method);
-            int first, last;
-            synchronized (routes) {
-                first = route.chosen >= 0 ? route.chosen : 0;
-                last = route.chosen >= 0 ? route.chosen : route.urls.size() - 1;
-            }
-            String refusal = null;
-            for (int i = first; i <= last; i++) {
-                up = Http.request(head ? "HEAD" : "GET", route.urls.get(i), h, null, 30000);
-                if (up.code < 400 || up.code == 416) {
-                    boolean firstTime;
-                    synchronized (routes) { firstTime = route.chosen < 0; route.chosen = i; }
-                    Listener l = listener;
-                    if (firstTime && l != null) l.onAccepted(id, i);
-                    break;
-                }
-                // refused: remember why, try the next variant
-                String body = "";
-                try { body = head ? "" : new String(up.readAll(), "UTF-8"); } catch (IOException ignored) {}
-                refusal = "Server refused the stream (" + up.code + ")" + (body.trim().length() > 0 ? ": " + com.minamp.plex.Plex.snippet(body) : "");
-                if (i < last) { up.close(); up = null; }
-            }
-            if (up.code >= 400 && up.code != 416) {
-                Listener l = listener;
-                if (l != null) l.onError(id, up.code, refusal);
-            }
-            synchronized (routes) {
-                if (!routes.containsKey(id)) { Http.abort(up); return; }
-                List<Http.Response> l = live.get(id);
-                if (l == null) { l = new ArrayList<Http.Response>(); live.put(id, l); }
-                l.add(up);
-            }
+            if (route.buffered) serveBuffered(route, out, head, reqHeaders.get("range"), path);
+            else servePassThrough(route, out, head, reqHeaders.get("range"), path);
+        } catch (IOException e) {
+            // player went away, track skipped, or the network dropped: just close
+        } catch (Throwable t) {
+            DiagLog.log("proxy error: " + Threads.describe(t));
+            Listener l = listener;
+            if (l != null && id != null) l.onError(id, 0, Threads.describe(t));
+        } finally {
+            try { s.close(); } catch (IOException ignored) {}
+        }
+    }
 
+    private static void writeEmpty(OutputStream out, int code, String reason) throws IOException {
+        out.write(("HTTP/1.0 " + code + " " + reason + "\r\nContent-Length: 0\r\nConnection: close\r\n\r\n").getBytes("ISO-8859-1"));
+        out.flush();
+    }
+
+    private static final class RefusedException extends IOException {
+        final int code;
+        RefusedException(int code, String msg) { super(msg); this.code = code; }
+    }
+
+    /** Tries the route's URLs in order; returns the accepted response or throws with the server's words. */
+    private Http.Response openUpstream(Route route, String method, String range, int first, int last) throws IOException {
+        Map<String, String> h = new LinkedHashMap<String, String>();
+        h.put("Accept", "*/*");
+        if (range != null) h.put("Range", range);
+        String refusal = null;
+        int code = 0;
+        for (int i = first; i <= last; i++) {
+            Http.Response up = Http.request(method, route.urls.get(i), h, null, 30000);
+            if (up.code < 400 || up.code == 416) {
+                Listener l = listener;
+                boolean firstTime;
+                synchronized (route) { firstTime = route.chosen < 0; route.chosen = i; }
+                if (firstTime && l != null) l.onAccepted(route.id, i);
+                return up;
+            }
+            String body = "";
+            try { body = "HEAD".equals(method) ? "" : new String(up.readAll(), "UTF-8"); } catch (IOException ignored) {}
+            up.close();
+            code = up.code;
+            refusal = "Server refused the stream (" + up.code + ")" + (body.trim().length() > 0 ? ": " + com.minamp.plex.Plex.snippet(body) : "");
+            DiagLog.log("stream variant " + i + " refused: " + refusal);
+        }
+        throw new RefusedException(code, refusal);
+    }
+
+    // ---- pass-through ----
+
+    private void servePassThrough(Route route, OutputStream out, boolean head, String range, String path) throws IOException {
+        int first, last;
+        synchronized (route) {
+            first = route.chosen >= 0 ? route.chosen : 0;
+            last = route.chosen >= 0 ? route.chosen : route.urls.size() - 1;
+        }
+        Http.Response up;
+        try {
+            up = openUpstream(route, head ? "HEAD" : "GET", range, first, last);
+        } catch (RefusedException e) {
+            Listener l = listener;
+            if (l != null) l.onError(route.id, e.code, e.getMessage());
+            writeEmpty(out, e.code, "Refused");
+            return;
+        }
+        synchronized (route) {
+            if (route.cancelled) { Http.abort(up); return; }
+            route.live.add(up);
+        }
+        try {
             StringBuilder resp = new StringBuilder(256);
-            boolean refused = up.code >= 400 && up.code != 416;
-            boolean known = !refused && up.contentLength >= 0 && !up.chunked;
+            boolean known = up.contentLength >= 0 && !up.chunked;
             resp.append(known ? "HTTP/1.1 " : "HTTP/1.0 ").append(up.code).append(' ').append(reason(up.code)).append("\r\n");
             String ct = up.header("content-type");
             if (ct == null || ct.startsWith("application/octet") || ct.startsWith("text/")) ct = guessType(path);
-            if (up.code >= 400) ct = "text/plain";
             resp.append("Content-Type: ").append(ct).append("\r\n");
             if (known) resp.append("Content-Length: ").append(up.contentLength).append("\r\n");
-            if (refused) resp.append("Content-Length: 0\r\n");
             String cr = up.header("content-range");
             if (cr != null) resp.append("Content-Range: ").append(cr).append("\r\n");
             String ar = up.header("accept-ranges");
@@ -196,35 +257,160 @@ public final class StreamProxy implements Runnable {
             resp.append("Connection: close\r\n\r\n");
             out.write(resp.toString().getBytes("ISO-8859-1"));
             out.flush();
-            if (head || up.code >= 400) { up.close(); up = null; return; }
-
+            if (head) { up.close(); return; }
             byte[] buf = new byte[16384];
             int n;
-            while ((n = up.body.read(buf)) > 0) {
-                out.write(buf, 0, n);
-            }
+            while ((n = up.body.read(buf)) > 0) out.write(buf, 0, n);
             out.flush();
             up.close();
-            synchronized (routes) {
-                List<Http.Response> l = live.get(id);
-                if (l != null) l.remove(up);
-            }
-            up = null;
-        } catch (IOException e) {
-            // player went away, track skipped, or the network dropped: just close
-        } catch (Throwable t) {
-            Listener l = listener;
-            if (l != null && id != null) l.onError(id, 0, Threads.describe(t));
         } finally {
-            if (up != null) Http.abort(up);
-            if (id != null && up != null) {
-                synchronized (routes) {
-                    List<Http.Response> l = live.get(id);
-                    if (l != null) l.remove(up);
+            Http.abort(up);
+            synchronized (route) { route.live.remove(up); }
+        }
+    }
+
+    // ---- buffered ----
+
+    private void startFetch(final Route route) {
+        synchronized (route) {
+            if (route.started) return;
+            route.started = true;
+            File dir = cacheDir != null ? cacheDir : new File(System.getProperty("java.io.tmpdir", "/tmp"));
+            route.file = new File(dir, "stream-" + route.id + ".mp3");
+        }
+        Threads.start(new Runnable() {
+            public void run() {
+                Http.Response up = null;
+                FileOutputStream fo = null;
+                try {
+                    up = openUpstream(route, "GET", null, 0, route.urls.size() - 1);
+                    synchronized (route) {
+                        if (route.cancelled) return;
+                        route.upstream = up;
+                    }
+                    fo = new FileOutputStream(route.file);
+                    byte[] buf = new byte[16384];
+                    int n;
+                    while ((n = up.body.read(buf)) > 0) {
+                        fo.write(buf, 0, n);
+                        fo.flush();
+                        synchronized (route) {
+                            if (route.cancelled) break;
+                            route.written += n;
+                            route.notifyAll();
+                        }
+                    }
+                    up.close();
+                    synchronized (route) { route.done = true; route.notifyAll(); }
+                } catch (RefusedException e) {
+                    boolean cancelled;
+                    synchronized (route) {
+                        route.failCode = e.code; route.failMessage = e.getMessage(); route.done = true;
+                        cancelled = route.cancelled;
+                        route.notifyAll();
+                    }
+                    Listener l = listener;
+                    if (l != null && !cancelled) l.onError(route.id, e.code, e.getMessage());
+                } catch (Throwable t) {
+                    boolean cancelled;
+                    synchronized (route) {
+                        if (route.failMessage == null) route.failMessage = Threads.describe(t);
+                        route.done = true;
+                        cancelled = route.cancelled;
+                        route.notifyAll();
+                    }
+                    if (!cancelled) DiagLog.log("stream download stopped: " + Threads.describe(t));
+                } finally {
+                    if (fo != null) try { fo.close(); } catch (IOException ignored) {}
+                    if (up != null) Http.abort(up);
                 }
             }
-            try { s.close(); } catch (IOException ignored) {}
+        }, "proxy-fetch");
+    }
+
+    private void serveBuffered(Route route, OutputStream out, boolean head, String range, String path) throws IOException {
+        startFetch(route);
+        long wantFrom = 0;
+        boolean done;
+        long written;
+        File file;
+        synchronized (route) {
+            long deadline = System.currentTimeMillis() + 60000;
+            while (!route.cancelled && route.written == 0 && !route.done) {
+                long left = deadline - System.currentTimeMillis();
+                if (left <= 0) break;
+                try { route.wait(left); } catch (InterruptedException e) { return; }
+            }
+            if (route.cancelled) { writeEmpty(out, 404, "Gone"); return; }
+            if (route.written == 0) {
+                int code = route.failCode > 0 ? route.failCode : 503;
+                writeEmpty(out, code, "Unavailable");
+                return;
+            }
+            done = route.done;
+            written = route.written;
+            file = route.file;
         }
+        // Ranges only once the whole stream is here (the length isn't known before that).
+        if (range != null && done && range.startsWith("bytes=")) {
+            try {
+                String r = range.substring(6);
+                int dash = r.indexOf('-');
+                wantFrom = Long.parseLong(r.substring(0, dash).trim());
+            } catch (Exception e) { wantFrom = 0; }
+            if (wantFrom >= written) { writeEmpty(out, 416, "Range Not Satisfiable"); return; }
+        }
+        StringBuilder resp = new StringBuilder(200);
+        if (done) {
+            resp.append(wantFrom > 0 ? "HTTP/1.1 206 Partial Content\r\n" : "HTTP/1.1 200 OK\r\n");
+            resp.append("Content-Length: ").append(written - wantFrom).append("\r\n");
+            resp.append("Accept-Ranges: bytes\r\n");
+            if (wantFrom > 0) resp.append("Content-Range: bytes ").append(wantFrom).append('-').append(written - 1).append('/').append(written).append("\r\n");
+        } else {
+            resp.append("HTTP/1.0 200 OK\r\n"); // length unknown: read until the connection closes
+        }
+        resp.append("Content-Type: ").append(guessType(path)).append("\r\nConnection: close\r\n\r\n");
+        out.write(resp.toString().getBytes("ISO-8859-1"));
+        out.flush();
+        if (head) return;
+
+        RandomAccessFile raf = new RandomAccessFile(file, "r");
+        try {
+            long pos = wantFrom;
+            byte[] buf = new byte[16384];
+            while (true) {
+                long avail;
+                boolean finished;
+                synchronized (route) {
+                    while (!route.cancelled && route.written <= pos && !route.done) {
+                        try { route.wait(5000); } catch (InterruptedException e) { return; }
+                    }
+                    if (route.cancelled) return;
+                    avail = route.written - pos;
+                    finished = route.done;
+                }
+                if (avail <= 0) {
+                    if (finished) break;
+                    continue;
+                }
+                raf.seek(pos);
+                int n = raf.read(buf, 0, (int) Math.min(buf.length, avail));
+                if (n <= 0) break;
+                out.write(buf, 0, n);
+                pos += n;
+            }
+            out.flush();
+        } finally {
+            raf.close();
+        }
+    }
+
+    /** True once a buffered route has its whole stream on disk (seeks can stay local then). */
+    public boolean isComplete(String id) {
+        Route r;
+        synchronized (routes) { r = id == null ? null : routes.get(id); }
+        if (r == null) return false;
+        synchronized (r) { return r.done && r.failMessage == null && r.written > 0; }
     }
 
     private static String reason(int code) {
diff --git a/src/com/minamp/plex/Library.java b/src/com/minamp/plex/Library.java
index 6a984ef..8ff93fa 100644
--- a/src/com/minamp/plex/Library.java
+++ b/src/com/minamp/plex/Library.java
@@ -173,11 +173,14 @@ public final class Library {
     }
 
     /**
-     * Plex servers differ in which form of the music transcoder request they accept (some answer
-     * 400 to one and stream fine with another), so there are several known variants. The proxy
-     * tries them in order; the one that worked is remembered and tried first next time.
+     * Plex only transcodes for a client identity it has a profile for: an unknown platform or
+     * device gets a bare 400 ("unable to find a matching profile"). These are request shapes
+     * known to work against real servers, tried in order; the one that works is remembered.
+     * Every variant gets its own session id: re-using one tears down the previous transcode
+     * (503s, tracks cut short).
      */
     public static final int VARIANTS = 4;
+    public static final String[] VARIANT_NAMES = {"web player", "web player + MP3 profile", "speaker profile", "generic audio"};
     public static volatile int preferredVariant = 0;
 
     public static int[] variantOrder() {
@@ -187,54 +190,83 @@ public final class Library {
         return order;
     }
 
+    public static String variantSession(String session, int variant) { return session + "-v" + variant; }
+
     /** MP3 transcode URLs over plain progressive HTTP starting at offsetMs, in {@link #variantOrder()} order. */
     public java.util.List<String> transcodeUrls(Item t, int kbps, long offsetMs, String session) throws IOException {
         int[] order = variantOrder();
         java.util.List<String> out = new ArrayList<String>();
-        for (int i = 0; i < order.length; i++) out.add(transcodeUrl(t, kbps, offsetMs, session, order[i]));
+        for (int i = 0; i < order.length; i++) out.add(transcodeUrl(t, kbps, offsetMs, variantSession(session, order[i]), order[i]));
         return out;
     }
 
-    String transcodeUrl(Item t, int kbps, long offsetMs, String session, int variant) throws IOException {
+    public String transcodeUrl(Item t, int kbps, long offsetMs, String session, int variant) throws IOException {
         if (kbps <= 0) kbps = 320;
-        String target = "add-transcode-target(type=musicProfile&context=streaming&protocol=http&container=mp3&audioCodec=mp3)";
-        String profile;
-        String platform;
-        String base = "/music/:/transcode/universal/start.mp3";
+        String mp3Target = "add-transcode-target(replace=true&type=musicProfile&context=streaming&protocol=http&container=mp3&audioCodec=mp3)";
+        String bitrateLimit = "+add-limitation(scope=musicCodec&scopeName=mp3&type=upperBound&name=audio.bitrate&value=" + kbps
+                + "&onlyTranscodes=true&replace=true)";
+        StringBuilder q = new StringBuilder();
+        String base;
+        q.append("path=").append(Plex.enc("/library/metadata/" + t.ratingKey));
         switch (variant) {
-            case 0:  // what Plex's own web player identifies as, with an explicit MP3 target
-                platform = "Chrome";
-                profile = target + "+add-limitation(scope=musicCodec&scopeName=*&type=upperBound&name=audio.bitrate&value=" + kbps + ")";
+            case 0:
+                // Plex Web's own identity and the minimal parameter set it uses for a progressive MP3
+                base = "/music/:/transcode/universal/start.mp3";
+                q.append("&protocol=http&mediaIndex=0&partIndex=0&audioCodec=mp3")
+                 .append("&directPlay=0&directStream=1&fastSeek=1&musicBitrate=").append(kbps);
                 break;
-            case 1:  // generic client profile
-                platform = "Generic";
-                profile = target + "+add-limitation(scope=musicCodec&scopeName=mp3&type=upperBound&name=audio.bitrate&value=" + kbps + ")";
+            case 1:
+                // same identity, forcing a real MP3 encode at our bitrate via a declared target
+                base = "/music/:/transcode/universal/start.mp3";
+                q.append("&protocol=http&mediaIndex=0&partIndex=0")
+                 .append("&directPlay=0&directStream=0&fastSeek=1&musicBitrate=").append(kbps)
+                 .append("&X-Plex-Client-Profile-Extra=").append(Plex.enc(mp3Target + bitrateLimit));
                 break;
-            case 2:  // older servers' audio endpoint
-                platform = "Chrome";
-                profile = target;
-                base = "/audio/:/transcode/universal/start.mp3";
+            case 2:
+                // a networked-speaker identity Plex ships a profile for; output decided by the target
+                base = "/audio/:/transcode/universal/start";
+                q.append("&directPlay=0&directStream=0&musicBitrate=").append(kbps)
+                 .append("&X-Plex-Client-Profile-Extra=").append(Plex.enc(mp3Target + bitrateLimit
+                    + "+add-limitation(scope=musicCodec&scopeName=mp3&type=upperBound&name=audio.samplingRate&value=48000&onlyTranscodes=true&replace=true)"));
                 break;
-            default: // no profile tweaks at all; bitrate from musicBitrate only
-                platform = "Chrome";
-                profile = null;
+            default:
+                base = "/audio/:/transcode/universal/start";
+                q.append("&protocol=http&directPlay=0&directStream=0&musicBitrate=").append(kbps)
+                 .append("&X-Plex-Client-Profile-Extra=").append(Plex.enc(mp3Target));
+        }
+        if (offsetMs >= 1000) q.append("&offset=").append(offsetMs / 1000);
+        q.append("&session=").append(Plex.enc(session))
+         .append("&X-Plex-Session-Identifier=").append(Plex.enc(session))
+         .append("&X-Plex-Client-Identifier=").append(Plex.enc(Plex.clientId))
+         .append("&X-Plex-Product=").append(Plex.enc(Plex.product))
+         .append("&X-Plex-Version=").append(Plex.enc(Plex.version));
+        if (variant == 2) {
+            q.append("&X-Plex-Platform=Linux&X-Plex-Platform-Version=1.0")
+             .append("&X-Plex-Device=Sonos&X-Plex-Device-Name=").append(Plex.enc(Plex.deviceName))
+             .append("&X-Plex-Model=sonos");
+        } else {
+            // no X-Plex-Device: a phone model name matches no server profile and gets a 400
+            q.append("&X-Plex-Platform=Chrome");
+        }
+        return server.url(base + "?" + q);
+    }
+
+    /** Ask the server what it would do with a transcode request (for the diagnostics screen). */
+    public String decision(Item t, int kbps, int variant) {
+        try {
+            String url = transcodeUrl(t, kbps, 0, "minamp-check-" + System.currentTimeMillis(), variant);
+            url = url.replace("/start.mp3?", "/decision?").replace("/universal/start?", "/universal/decision?");
+            com.minamp.net.Http.Response r = com.minamp.net.Http.get(url, Plex.headers(null), 20000);
+            String body = r.readString();
+            if (r.code != 200) return "HTTP " + r.code + (Plex.snippet(body).length() > 0 ? ": " + Plex.snippet(body) : "");
+            Json.Obj mc = Json.parseObj(body).optObj("MediaContainer");
+            if (mc == null) return "200 (no details)";
+            return "general " + mc.optString("generalDecisionCode", "?") + " " + mc.optString("generalDecisionText", "")
+                    + " | transcode " + mc.optString("transcodeDecisionCode", "?") + " " + mc.optString("transcodeDecisionText", "")
+                    + " | direct play " + mc.optString("directPlayDecisionCode", "?") + " " + mc.optString("directPlayDecisionText", "");
+        } catch (Exception e) {
+            return com.minamp.net.Threads.describe(e);
         }
-        String path = base
-                + "?path=" + Plex.enc("/library/metadata/" + t.ratingKey)
-                + "&mediaIndex=0&partIndex=0&protocol=http&hasMDE=1&fastSeek=1&copyts=1"
-                + "&directPlay=0&directStream=0&directStreamAudio=0"
-                + "&musicBitrate=" + kbps + "&maxAudioBitrate=" + kbps
-                + "&offset=" + (offsetMs / 1000)
-                + "&session=" + Plex.enc(session)
-                + "&location=" + (server.isLocal() ? "lan" : "wan")
-                + "&X-Plex-Session-Identifier=" + Plex.enc(session)
-                + "&X-Plex-Client-Identifier=" + Plex.enc(Plex.clientId)
-                + "&X-Plex-Product=" + Plex.enc(Plex.product)
-                + "&X-Plex-Version=" + Plex.enc(Plex.version)
-                + "&X-Plex-Platform=" + platform
-                + "&X-Plex-Device=" + Plex.enc(Plex.device)
-                + (profile != null ? "&X-Plex-Client-Profile-Extra=" + Plex.enc(profile) : "");
-        return server.url(path);
     }
 
     public void stopTranscode(String session) {
diff --git a/src/com/minamp/plex/Plex.java b/src/com/minamp/plex/Plex.java
index c2702e5..d50da58 100644
--- a/src/com/minamp/plex/Plex.java
+++ b/src/com/minamp/plex/Plex.java
@@ -52,6 +52,7 @@ public final class Plex {
         if (r.code == 401) throw new PlexException(401, "Not authorized (401) on " + describePath(url));
         if (r.code < 200 || r.code >= 300) {
             String snippet = snippet(body);
+            com.minamp.net.DiagLog.log("  server said: " + snippet);
             throw new PlexException(r.code, "HTTP " + r.code + " on " + describePath(url) + (snippet.length() > 0 ? ": " + snippet : ""));
         }
         if (body.trim().length() == 0) return new Json.Obj();
diff --git a/test/PlexTest.java b/test/PlexTest.java
index 24aa0e2..478483d 100644
--- a/test/PlexTest.java
+++ b/test/PlexTest.java
@@ -130,25 +130,48 @@ public class PlexTest {
             public void onError(String id, int code, String m) { refused[0] = code + " " + m; }
             public void onAccepted(String id, int index) { accepted[0] = index; }
         };
+        java.io.File cache = new java.io.File(System.getProperty("java.io.tmpdir"), "minamp-test-cache");
+        cache.mkdirs();
+        proxy.cacheDir = cache;
+        Library.preferredVariant = 0;
         String id2 = proxy.newId();
-        String local2 = proxy.register(id2, lib.transcodeUrls(tracks.get(1), 192, 30500, "sess1"), "mp3");
+        String local2 = proxy.register(id2, lib.transcodeUrls(tracks.get(1), 192, 30500, "sess1"), "mp3", true);
         hc = (HttpURLConnection) new URL(local2).openConnection(Proxy.NO_PROXY);
         byte[] tbody = read(hc.getInputStream());
         String ts = new String(tbody, "ISO-8859-1");
-        check(hc.getResponseCode() == 200 && ts.startsWith("TRANSCODE offset=30 bitrate=192|") && hc.getHeaderField("Content-Length") == null,
-              "proxy de-chunks transcode stream (" + tbody.length + "B)");
-        check(accepted[0] == 1 && refused[0] == null, "refused transcode variant skipped, second accepted (index " + accepted[0] + ")");
-        Library.preferredVariant = Library.variantOrder()[accepted[0]];
-        check(Library.variantOrder()[0] == 1, "accepted variant is tried first next time");
-        // every variant refused -> error carries the server's words
-        Library.preferredVariant = 0;
+        check(hc.getResponseCode() == 200 && ts.startsWith("TRANSCODE offset=30 bitrate=192|"),
+              "buffered transcode stream served (" + tbody.length + "B)");
+        check(accepted[0] == 0 && refused[0] == null, "web-player identity accepted first time (variant " + accepted[0] + ")");
+        // the media player reconnecting must not start the transcode again (that's the 503)
+        hc = (HttpURLConnection) new URL(local2).openConnection(Proxy.NO_PROXY);
+        byte[] again = read(hc.getInputStream());
+        check(hc.getResponseCode() == 200 && again.length == tbody.length && refused[0] == null,
+              "reconnect served from the buffer, no second transcode (" + again.length + "B)");
+        hc = (HttpURLConnection) new URL(local2).openConnection(Proxy.NO_PROXY);
+        hc.setRequestProperty("Range", "bytes=100-");
+        byte[] part = read(hc.getInputStream());
+        check(hc.getResponseCode() == 206 && part.length == tbody.length - 100 && proxy.isComplete(id2),
+              "seek within a finished transcode via Range (" + part.length + "B)");
+        check(!lib.transcodeUrls(tracks.get(1), 192, 0, "x").get(0).contains("X-Plex-Device=")
+              && lib.transcodeUrls(tracks.get(1), 192, 0, "x").get(0).contains("session=x-v0"),
+              "no phone model in transcode identity; per-variant session ids");
+        String dec = lib.decision(tracks.get(1), 192, 0);
+        check(dec.indexOf("Conversion OK") >= 0, "decision check reads the server's verdict: " + dec);
+        check(lib.decision(tracks.get(1), 192, 2).indexOf("Conversion OK") >= 0, "speaker-profile variant also accepted by profile matching");
+        // a server that refuses everything: error carries the server's own words
         String id4 = proxy.newId();
         java.util.List<String> bad = new java.util.ArrayList<String>();
-        bad.add(lib.transcodeUrls(tracks.get(1), 192, 0, "s4").get(0));
-        String local4 = proxy.register(id4, bad, "mp3");
+        bad.add(lib.transcodeUrls(tracks.get(1), 192, 0, "s4").get(0).replace("X-Plex-Platform=Chrome", "X-Plex-Platform=Android"));
+        String local4 = proxy.register(id4, bad, "mp3", true);
         hc = (HttpURLConnection) new URL(local4).openConnection(Proxy.NO_PROXY);
         int c4 = hc.getResponseCode();
-        check(c4 == 400 && refused[0] != null && refused[0].indexOf("400 Bad Request") >= 0, "refusal reported with server text: " + refused[0]);
+        check(c4 == 400 && refused[0] != null && refused[0].indexOf("400 Bad Request") >= 0, "unrecognised identity -> refusal with server text: " + refused[0]);
+        // the pre-fix request shape (phone model as device) is exactly what a real server refuses
+        String old = lib.transcodeUrls(tracks.get(1), 192, 0, "s5").get(0).replace("X-Plex-Platform=Chrome", "X-Plex-Platform=Chrome&X-Plex-Device=GT-S5570");
+        Http.Response or = Http.get(old, null, 10000);
+        or.readAll();
+        check(or.code == 400, "mock reproduces the 400 for the old phone-model identity");
+        Library.preferredVariant = 0;
 
         // abort mid-stream
         String id3 = proxy.newId();
diff --git a/test/mock_plex.py b/test/mock_plex.py
index ac40578..3ad398a 100644
--- a/test/mock_plex.py
+++ b/test/mock_plex.py
@@ -61,6 +61,7 @@ TOKEN = "server-token-xyz"
 ACCOUNT = "account-token-123"
 pins = {}
 log = []
+starts = []
 
 TRACKS = [
     {"type": "track", "ratingKey": "101", "key": "/library/metadata/101", "title": "Song One", "grandparentTitle": "The Testers",
@@ -141,7 +142,24 @@ class H(BaseHTTPRequestHandler):
                 {"type": "track", "title": "Tracks", "Metadata": TRACKS[:1]}]}})
         if p.startswith("/library/parts/501"):
             return self.file(method, MP3)
-        if p in ("/music/:/transcode/universal/start.mp3", "/audio/:/transcode/universal/start.mp3"):
+        if p.endswith("/transcode/universal/decision"):
+            if not self.profile_ok(q):
+                return self.send_json({"error": "unable to find a matching profile"}, 400)
+            return self.send_json({"MediaContainer": {"generalDecisionCode": 1001, "generalDecisionText": "Direct play not available; Conversion OK.",
+                                                      "transcodeDecisionCode": 1001, "transcodeDecisionText": "Transcode OK."}})
+        if p in ("/music/:/transcode/universal/start.mp3", "/audio/:/transcode/universal/start.mp3", "/audio/:/transcode/universal/start"):
+            # like a real server: unknown client identity -> 400; a session started twice -> 503
+            if not self.profile_ok(q):
+                body = b"<html><body><h1>400 Bad Request</h1></body></html>"
+                self.send_response(400)
+                self.send_header("Content-Type", "text/html")
+                self.send_header("Content-Length", str(len(body)))
+                self.end_headers()
+                return self.wfile.write(body)
+            sess = (q.get("session") or [""])[0]
+            starts.append(sess)
+            if starts.count(sess) > 1:
+                return self.send_json({"error": "session busy"}, 503)
             extra = (q.get("X-Plex-Client-Profile-Extra") or [""])[0]
             if "scopeName=*" in extra:  # pretend this server rejects that variant
                 body = b"<html><head><title>Bad Request</title></head><body><h1>400 Bad Request</h1></body></html>"
@@ -157,6 +175,11 @@ class H(BaseHTTPRequestHandler):
             return self.send_json({})
         self.send_json({"error": "not found " + p}, 404)
 
+    def profile_ok(self, q):
+        platform = (q.get("X-Plex-Platform") or [""])[0]
+        device = (q.get("X-Plex-Device") or [""])[0]
+        return platform in ("Chrome", "Linux") and device in ("", "Sonos")
+
     def file(self, method, data, ctype="audio/mpeg"):
         rng = self.headers.get("Range")
         start, end = 0, len(data) - 1