Minamp 1.2

- Transcoding: send client identities Plex has a profile for (unknown ones get
  400 "unable to find a matching profile"), with a fresh session id per variant
- Stream proxy: fetch transcodes once into a temp file and serve every player
  request from it, so reconnects no longer restart the transcode (503s, tracks
  cut short); original files still pass Range requests through
- Sign-in: remember the pending link code so it survives Minamp being closed
  while the code is entered elsewhere; add "I've entered it - check now"
- Diagnostics: in-app connection log (DiagLog) with a streaming test and save
  to SD card; tokens are never logged

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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) {