WIP checkpoint: Phase 5(b) narya streamer codegen for ART field-order

Pre-crash safety checkpoint (box rebooted mid-implementation; NOT verified
complete). GenStreamableTask flatten-mode + GenStreamUtil runtime helper +
ObjectInputStream changes; explicit read/writeObject instrumentation across
presents net + dobj event classes so ART matches HotSpot's ClassUtil.getFields
order without the global sort flag (no data migration). narya 1.21.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HhfHCXYp2ctWi76Z91y9Ut

core/pom.xml

@@ -4,7 +4,7 @@
   <parent>
     <groupId>com.threerings</groupId>
     <artifactId>narya-parent</artifactId>
-    <version>1.20</version>
+    <version>1.21</version>
   </parent>
 
   <artifactId>narya</artifactId>

core/src/main/java/com/threerings/io/GenStreamUtil.java

@@ -0,0 +1,107 @@
+//
+// Narya library - tools for developing networked games
+// Copyright (C) 2002-2025 Three Rings Design, Inc., All Rights Reserved
+// https://github.com/threerings/narya/blob/master/LICENSE
+
+package com.threerings.io;
+
+import java.lang.reflect.Field;
+import java.util.concurrent.ConcurrentHashMap;
+
+import java.io.IOException;
+
+/**
+ * Runtime support for the explicit {@code readObject}/{@code writeObject} methods emitted by {@link
+ * com.threerings.presents.tools.GenStreamableTask} in "flatten" mode.
+ *
+ * <p>The default reflective {@link Streamer} streams a class's fields in {@link
+ * com.samskivert.util.ClassUtil#getFields} order, which is <em>superclass-first</em> but relies on
+ * {@link Class#getDeclaredFields} <em>within</em> each class. That per-class order is not defined by
+ * the JVM spec and differs between HotSpot (server/desktop) and ART (Android) &mdash; so a default
+ * streamed object written by one and read by the other misaligns. The generated methods stream each
+ * field explicitly, in an order captured from HotSpot at build time, by calling {@link #readField}/
+ * {@link #writeField} here. Because those methods delegate to the very same {@link FieldMarshaller}
+ * the reflective streamer uses, the produced bytes are identical to the legacy reflective form on
+ * HotSpot (so existing persisted boards and DB blobs read unchanged, and desktop&harr;server is
+ * unaffected) while being deterministic on ART.
+ */
+public final class GenStreamUtil
+{
+    /**
+     * Reads the named field of {@code target} (declared by {@code declaringClass}) from the stream,
+     * using the same {@link FieldMarshaller} the reflective streamer would use.
+     */
+    public static void readField (
+        Class<?> declaringClass, String name, Object target, ObjectInputStream in)
+        throws IOException, ClassNotFoundException
+    {
+        Entry entry = entry(declaringClass, name);
+        try {
+            entry.marshaller.readField(entry.field, target, in);
+        } catch (IOException ioe) {
+            throw ioe;
+        } catch (ClassNotFoundException cnfe) {
+            throw cnfe;
+        } catch (RuntimeException re) {
+            throw re;
+        } catch (Exception e) {
+            throw new IOException("Failure reading field [class=" + declaringClass.getName() +
+                                  ", field=" + name + "]", e);
+        }
+    }
+
+    /**
+     * Writes the named field of {@code source} (declared by {@code declaringClass}) to the stream,
+     * using the same {@link FieldMarshaller} the reflective streamer would use.
+     */
+    public static void writeField (
+        Class<?> declaringClass, String name, Object source, ObjectOutputStream out)
+        throws IOException
+    {
+        Entry entry = entry(declaringClass, name);
+        try {
+            entry.marshaller.writeField(entry.field, source, out);
+        } catch (IOException ioe) {
+            throw ioe;
+        } catch (RuntimeException re) {
+            throw re;
+        } catch (Exception e) {
+            throw new IOException("Failure writing field [class=" + declaringClass.getName() +
+                                  ", field=" + name + "]", e);
+        }
+    }
+
+    protected static Entry entry (Class<?> declaringClass, String name)
+    {
+        String key = declaringClass.getName() + "#" + name;
+        Entry entry = _cache.get(key);
+        if (entry == null) {
+            Field field;
+            try {
+                field = declaringClass.getDeclaredField(name);
+            } catch (NoSuchFieldException nsfe) {
+                throw new RuntimeException("Missing streamed field [class=" +
+                                           declaringClass.getName() + ", field=" + name + "]", nsfe);
+            }
+            field.setAccessible(true);
+            entry = new Entry(field, FieldMarshaller.getFieldMarshaller(field));
+            _cache.put(key, entry);
+        }
+        return entry;
+    }
+
+    protected static final class Entry
+    {
+        public final Field field;
+        public final FieldMarshaller marshaller;
+        public Entry (Field field, FieldMarshaller marshaller) {
+            this.field = field;
+            this.marshaller = marshaller;
+        }
+    }
+
+    /** Caches the resolved (accessible) field + its marshaller, keyed by declaring class + name. */
+    protected static final ConcurrentHashMap<String, Entry> _cache = new ConcurrentHashMap<String, Entry>();
+
+    private GenStreamUtil () {}
+}

core/src/main/java/com/threerings/io/ObjectInputStream.java

@@ -412,5 +412,5 @@ public class ObjectInputStream extends DataInputStream
     protected static volatile List<String> _allowedPrefixes;
 
     /** Used to activate verbose debug logging. */
-    protected static final boolean STREAM_DEBUG = false;
+    protected static final boolean STREAM_DEBUG = Boolean.getBoolean("com.threerings.io.streamDebug");
 }

core/src/main/java/com/threerings/presents/dobj/AttributeChangedEvent.java

@@ -165,4 +165,24 @@ public class AttributeChangedEvent extends NamedEvent
 
     protected Object _value;
     protected transient Object _oldValue = UNSET_OLD_VALUE;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.AttributeChangedEvent.class, "_value", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.AttributeChangedEvent.class, "_value", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/CompoundEvent.java

@@ -173,4 +173,22 @@ public class CompoundEvent extends DEvent
 
     /** A list of the events associated with this compound event. */
     protected StreamableArrayList<DEvent> _events;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.CompoundEvent.class, "_events", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.CompoundEvent.class, "_events", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/ElementUpdatedEvent.java

@@ -178,4 +178,26 @@ public class ElementUpdatedEvent extends NamedEvent
     protected Object _value;
     protected int _index;
     protected transient Object _oldValue = UNSET_OLD_VALUE;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.ElementUpdatedEvent.class, "_value", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.ElementUpdatedEvent.class, "_index", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.ElementUpdatedEvent.class, "_value", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.ElementUpdatedEvent.class, "_index", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/EntryAddedEvent.java

@@ -107,4 +107,24 @@ public class EntryAddedEvent<T extends DSet.Entry> extends EntryEvent<T>
     /** Used when this event is generated on the authoritative server where object changes are made
      * immediately. This lets us know not to apply ourselves when we're actually dispatched. */
     protected transient boolean _alreadyApplied;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.EntryAddedEvent.class, "_entry", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.EntryAddedEvent.class, "_entry", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/EntryRemovedEvent.java

@@ -109,4 +109,24 @@ public class EntryRemovedEvent<T extends DSet.Entry> extends EntryEvent<T>
 
     @SuppressWarnings("unchecked")
     protected transient T _oldEntry = (T)UNSET_OLD_ENTRY;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.EntryRemovedEvent.class, "_key", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.EntryRemovedEvent.class, "_key", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/EntryUpdatedEvent.java

@@ -112,4 +112,24 @@ public class EntryUpdatedEvent<T extends DSet.Entry> extends EntryEvent<T>
 
     @SuppressWarnings("unchecked")
     protected transient T _oldEntry = (T)UNSET_OLD_ENTRY;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.EntryUpdatedEvent.class, "_entry", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.EntryUpdatedEvent.class, "_entry", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/InvocationNotificationEvent.java

@@ -89,4 +89,26 @@ public class InvocationNotificationEvent extends DEvent
 
     /** The arguments to the receiver method being invoked. */
     protected Object[] _args;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.InvocationNotificationEvent.class, "_receiverId", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.InvocationNotificationEvent.class, "_methodId", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.InvocationNotificationEvent.class, "_args", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.InvocationNotificationEvent.class, "_receiverId", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.InvocationNotificationEvent.class, "_methodId", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.InvocationNotificationEvent.class, "_args", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/InvocationRequestEvent.java

@@ -89,4 +89,26 @@ public class InvocationRequestEvent extends DEvent
 
     /** The arguments to the method being invoked. */
     protected Object[] _args;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.InvocationRequestEvent.class, "_invCode", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.InvocationRequestEvent.class, "_methodId", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.InvocationRequestEvent.class, "_args", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.InvocationRequestEvent.class, "_invCode", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.InvocationRequestEvent.class, "_methodId", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.InvocationRequestEvent.class, "_args", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/InvocationResponseEvent.java

@@ -88,4 +88,26 @@ public class InvocationResponseEvent extends DEvent
 
     /** The arguments to the method being invoked. */
     protected Object[] _args;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.InvocationResponseEvent.class, "_requestId", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.InvocationResponseEvent.class, "_methodId", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.InvocationResponseEvent.class, "_args", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.InvocationResponseEvent.class, "_requestId", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.InvocationResponseEvent.class, "_methodId", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.InvocationResponseEvent.class, "_args", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/MessageEvent.java

@@ -74,4 +74,24 @@ public class MessageEvent extends NamedEvent
     }
 
     protected Object[] _args;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.MessageEvent.class, "_args", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.MessageEvent.class, "_args", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/ObjectAddedEvent.java

@@ -78,4 +78,24 @@ public class ObjectAddedEvent extends NamedEvent
 
     protected int _oid;
     protected transient boolean _alreadyApplied;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.ObjectAddedEvent.class, "_oid", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.ObjectAddedEvent.class, "_oid", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/ObjectDestroyedEvent.java

@@ -47,4 +47,20 @@ public class ObjectDestroyedEvent extends DEvent
         buf.append("DESTROY:");
         super.toString(buf);
     }
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/ObjectRemovedEvent.java

@@ -78,4 +78,24 @@ public class ObjectRemovedEvent extends NamedEvent
 
     protected int _oid;
     protected transient boolean _alreadyApplied;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.ObjectRemovedEvent.class, "_oid", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.ObjectRemovedEvent.class, "_oid", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/ReleaseLockEvent.java

@@ -55,4 +55,22 @@ public class ReleaseLockEvent extends NamedEvent
         buf.append("UNLOCK:");
         super.toString(buf);
     }
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/dobj/ServerMessageEvent.java

@@ -31,4 +31,24 @@ public class ServerMessageEvent extends MessageEvent
         // this is what makes us server-only
         return true;
     }
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.DEvent.class, "_toid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.dobj.MessageEvent.class, "_args", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.DEvent.class, "_toid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.NamedEvent.class, "_name", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.dobj.MessageEvent.class, "_args", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/net/AESAuthRequest.java

@@ -113,7 +113,11 @@ public class AESAuthRequest extends AuthRequest
     public void writeObject (ObjectOutputStream out)
         throws IOException
     {
-        out.defaultWriteObject();
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.UpstreamMessage.class, "messageId", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.AuthRequest.class, "_creds", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.AuthRequest.class, "_version", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.AuthRequest.class, "_zone", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.AuthRequest.class, "_bootGroups", this, out);
         ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
         ObjectOutputStream oOut = new ObjectOutputStream(byteOut);
         oOut.writeObject(_clearCreds);
@@ -136,7 +140,11 @@ public class AESAuthRequest extends AuthRequest
     public void readObject (ObjectInputStream in)
         throws IOException, ClassNotFoundException
     {
-        in.defaultReadObject();
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.UpstreamMessage.class, "messageId", this, in);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.AuthRequest.class, "_creds", this, in);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.AuthRequest.class, "_version", this, in);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.AuthRequest.class, "_zone", this, in);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.AuthRequest.class, "_bootGroups", this, in);
         _contents = new byte[in.readInt()];
         in.read(_contents);
     }

core/src/main/java/com/threerings/presents/net/AuthRequest.java

@@ -89,7 +89,11 @@ public class AuthRequest extends UpstreamMessage
         throws IOException, ClassNotFoundException
     {
         try {
-            in.defaultReadObject();
+            com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.UpstreamMessage.class, "messageId", this, in);
+            com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.AuthRequest.class, "_creds", this, in);
+            com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.AuthRequest.class, "_version", this, in);
+            com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.AuthRequest.class, "_zone", this, in);
+            com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.AuthRequest.class, "_bootGroups", this, in);
         } catch (IOException ioe) {
             // if we fail here because the client is old, leave ourselves with a partially
             // initialized set of credentials, which the server will generally cope with by telling
@@ -108,4 +112,17 @@ public class AuthRequest extends UpstreamMessage
 
     /** The set of bootstrap service groups this client is interested in. */
     protected String[] _bootGroups;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.UpstreamMessage.class, "messageId", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.AuthRequest.class, "_creds", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.AuthRequest.class, "_version", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.AuthRequest.class, "_zone", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.AuthRequest.class, "_bootGroups", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/net/FailureResponse.java

@@ -45,4 +45,24 @@ public class FailureResponse extends DownstreamMessage
 
     protected int _oid;
     protected String _message;
+
+    // AUTO-GENERATED: METHODS START
+    // from interface Streamable
+    public void readObject (com.threerings.io.ObjectInputStream ins)
+        throws java.io.IOException, java.lang.ClassNotFoundException
+    {
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.DownstreamMessage.class, "messageId", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.FailureResponse.class, "_oid", this, ins);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.FailureResponse.class, "_message", this, ins);
+    }
+
+    // from interface Streamable
+    public void writeObject (com.threerings.io.ObjectOutputStream out)
+        throws java.io.IOException
+    {
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.DownstreamMessage.class, "messageId", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.FailureResponse.class, "_oid", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.FailureResponse.class, "_message", this, out);
+    }
+    // AUTO-GENERATED: METHODS END
 }

core/src/main/java/com/threerings/presents/net/PingRequest.java

@@ -63,7 +63,7 @@ public class PingRequest extends UpstreamMessage
         // network
         _packStamp = System.currentTimeMillis();
 
-        out.defaultWriteObject();
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.UpstreamMessage.class, "messageId", this, out);
     }
 
     /**
@@ -76,7 +76,7 @@ public class PingRequest extends UpstreamMessage
         // the network
         _unpackStamp = System.currentTimeMillis();
 
-        in.defaultReadObject();
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.UpstreamMessage.class, "messageId", this, in);
     }
 
     @Override

core/src/main/java/com/threerings/presents/net/PongResponse.java

@@ -83,7 +83,9 @@ public class PongResponse extends DownstreamMessage
             _processDelay = (int)(_packStamp - _pingStamp);
         }
 
-        out.defaultWriteObject();
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.DownstreamMessage.class, "messageId", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.PongResponse.class, "_packStamp", this, out);
+        com.threerings.io.GenStreamUtil.writeField(com.threerings.presents.net.PongResponse.class, "_processDelay", this, out);
     }
 
     /**
@@ -96,7 +98,9 @@ public class PongResponse extends DownstreamMessage
         // the network
         _unpackStamp = System.currentTimeMillis();
 
-        in.defaultReadObject();
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.DownstreamMessage.class, "messageId", this, in);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.PongResponse.class, "_packStamp", this, in);
+        com.threerings.io.GenStreamUtil.readField(com.threerings.presents.net.PongResponse.class, "_processDelay", this, in);
     }
 
     @Override

pom.xml

@@ -5,7 +5,7 @@
   <groupId>com.threerings</groupId>
   <artifactId>narya-parent</artifactId>
   <packaging>pom</packaging>
-  <version>1.20</version>
+  <version>1.21</version>
 
   <name>Narya Parent</name>
   <description>Facilities for making networked multiplayer games.</description>

tools/pom.xml

@@ -4,7 +4,7 @@
   <parent>
     <groupId>com.threerings</groupId>
     <artifactId>narya-parent</artifactId>
-    <version>1.20</version>
+    <version>1.21</version>
   </parent>
 
   <artifactId>narya-tools</artifactId>

tools/src/main/java/com/threerings/presents/tools/GenStreamableTask.java

@@ -6,16 +6,24 @@
 package com.threerings.presents.tools;
 
 import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
 import java.util.ArrayList;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.file.Files;
 
 import org.apache.tools.ant.DirectoryScanner;
 import org.apache.tools.ant.types.FileSet;
 
 import com.google.common.collect.Lists;
 
+import com.samskivert.util.ClassUtil;
+
+import com.threerings.io.NotStreamable;
 import com.threerings.io.Streamable;
 
 import com.threerings.presents.dobj.DObject;
@@ -36,6 +44,21 @@ public class GenStreamableTask extends GenTask
         _filesets.add(set);
     }
 
+    /**
+     * If set, generate <em>self-contained</em> declaration-ordered {@code read/writeObject} methods
+     * that stream the entire flattened field set (in {@link ClassUtil#getFields} order, captured on
+     * HotSpot at build time) via {@link com.threerings.io.GenStreamUtil}, rather than the legacy
+     * per-class {@code super.read/writeObject(...)} + local-fields form. In this mode {@link DObject}
+     * subclasses are processed too, and a pass-through {@code readObject}/{@code writeObject} (one
+     * that calls {@code defaultReadObject}/{@code defaultWriteObject}) has that call replaced in
+     * place with the explicit field streaming (preserving any surrounding logic). This is what makes
+     * Streamables deterministic on ART (Android) while staying byte-identical on HotSpot. See {@link
+     * com.threerings.io.GenStreamUtil}.
+     */
+    public void setFlatten (boolean flatten) {
+        _flatten = flatten;
+    }
+
     @Override
     public void execute ()
     {
@@ -86,6 +109,11 @@ public class GenStreamableTask extends GenTask
     protected void processClass (File source, Class<?> sclass)
         throws IOException
     {
+        if (_flatten) {
+            processFlatten(source, sclass);
+            return;
+        }
+
         StreamableClassRequirements reqs = new StreamableClassRequirements(sclass);
         // we must implement Streamable, not be a DObject and have some fields that need to be
         // streamed
@@ -144,6 +172,164 @@ public class GenStreamableTask extends GenTask
         writeFile(source.getAbsolutePath(), sfile.generate(null, methods.toString()));
     }
 
+    /**
+     * "Flatten" mode: emit self-contained declaration-ordered {@code read/writeObject} that stream
+     * the whole {@link ClassUtil#getFields} field set via {@link com.threerings.io.GenStreamUtil}.
+     * Handles {@link DObject}s and replaces pass-through {@code default*Object()} calls in place.
+     */
+    protected void processFlatten (File source, Class<?> sclass)
+        throws IOException
+    {
+        // must be a concrete Streamable; never instrument abstract bases (their concrete subclasses
+        // stream the full flattened field set themselves, so an abstract base carrying a read/write
+        // method would "poison" any subclass that didn't get its own — silently dropping fields)
+        if (!Streamable.class.isAssignableFrom(sclass) || sclass.isInterface() ||
+                sclass.isEnum() || Modifier.isAbstract(sclass.getModifiers())) {
+            return;
+        }
+
+        // gather the streamed fields in the exact order the reflective streamer uses (superclass
+        // first, then this class's declared fields), skipping @NotStreamable and closure refs
+        List<Field> fields = Lists.newArrayList();
+        for (Field field : ClassUtil.getFields(sclass)) {
+            if (field.getAnnotation(NotStreamable.class) != null) {
+                continue;
+            }
+            if (field.isSynthetic() && field.getName().startsWith("this$")) {
+                continue;
+            }
+            fields.add(field);
+        }
+        if (fields.isEmpty()) {
+            return;
+        }
+
+        String src = new String(Files.readAllBytes(source.toPath()));
+
+        boolean hasRead = src.contains("public void readObject");
+        boolean hasWrite = src.contains("public void writeObject");
+        boolean hasReadDefault = DEFAULT_READ.matcher(src).find();
+        boolean hasWriteDefault = DEFAULT_WRITE.matcher(src).find();
+
+        // if either method is hand-written custom streaming (present, but NOT a defaultXObject
+        // pass-through), the class fully manages its own streaming and is already deterministic;
+        // leave it entirely alone rather than risk a generated/hand-written mismatch
+        if ((hasRead && !hasReadDefault) || (hasWrite && !hasWriteDefault)) {
+            return;
+        }
+
+        // build whole methods for any streaming direction that has no method at all
+        StringBuilder methods = new StringBuilder();
+        if (!hasRead) {
+            methods.append(FLAT_READ_OPEN);
+            for (Field field : fields) {
+                methods.append("        ").append(flatReadStatement(field, "ins")).append("\n");
+            }
+            methods.append(READ_CLOSE);
+        }
+        if (!hasWrite) {
+            if (methods.length() > 0) {
+                methods.append("\n");
+            }
+            methods.append(FLAT_WRITE_OPEN);
+            for (Field field : fields) {
+                methods.append("        ").append(flatWriteStatement(field, "out")).append("\n");
+            }
+            methods.append(WRITE_CLOSE);
+        }
+
+        boolean changed = false;
+        // replace a pass-through default read/write call in place, preserving surrounding logic
+        if (hasReadDefault) {
+            src = substituteDefault(src, DEFAULT_READ, fields, true);
+            changed = true;
+        }
+        if (hasWriteDefault) {
+            src = substituteDefault(src, DEFAULT_WRITE, fields, false);
+            changed = true;
+        }
+        // insert whole methods just before the class-closing brace, so we NEVER disturb the
+        // "// AUTO-GENERATED: METHODS" section (which holds the gendobj/genservice accessors) —
+        // SourceFile.generate() would replace that section wholesale and drop the accessors
+        if (methods.length() > 0) {
+            src = insertBeforeClassClose(src, methods.toString());
+            changed = true;
+        }
+        if (changed) {
+            System.err.println("Converting (flatten) " + sclass.getName() + "...");
+            writeFile(source.getAbsolutePath(), src);
+        }
+    }
+
+    /**
+     * Inserts {@code methods} (already 4-space indented, newline-terminated) just before the final
+     * top-level class-closing brace of {@code src}.
+     */
+    protected String insertBeforeClassClose (String src, String methods)
+    {
+        String[] lines = src.split("\n", -1);
+        int lastBrace = -1;
+        for (int ii = 0; ii < lines.length; ii++) {
+            if (lines[ii].trim().equals("}")) {
+                lastBrace = ii;
+            }
+        }
+        if (lastBrace < 0) {
+            throw new RuntimeException("No class-closing brace found");
+        }
+        StringBuilder sb = new StringBuilder();
+        for (int ii = 0; ii < lines.length; ii++) {
+            if (ii == lastBrace) {
+                sb.append("\n").append(methods);
+            }
+            sb.append(lines[ii]);
+            if (ii < lines.length - 1) {
+                sb.append("\n");
+            }
+        }
+        return sb.toString();
+    }
+
+    /**
+     * Replaces the single {@code recv.defaultReadObject()} / {@code recv.defaultWriteObject()}
+     * statement matched by {@code pat} with an explicit, same-indentation block that streams every
+     * field via {@link com.threerings.io.GenStreamUtil}, reusing the receiver variable name.
+     */
+    protected String substituteDefault (String src, Pattern pat, List<Field> fields, boolean read)
+    {
+        Matcher m = pat.matcher(src);
+        StringBuffer sb = new StringBuffer();
+        while (m.find()) {
+            String indent = m.group(1), recv = m.group(2);
+            StringBuilder block = new StringBuilder();
+            for (int ii = 0; ii < fields.size(); ii++) {
+                if (ii > 0) {
+                    block.append("\n");
+                }
+                Field field = fields.get(ii);
+                block.append(indent).append(
+                    read ? flatReadStatement(field, recv) : flatWriteStatement(field, recv));
+            }
+            m.appendReplacement(sb, Matcher.quoteReplacement(block.toString()));
+        }
+        m.appendTail(sb);
+        return sb.toString();
+    }
+
+    protected String flatReadStatement (Field field, String recv)
+    {
+        return "com.threerings.io.GenStreamUtil.readField(" +
+            field.getDeclaringClass().getCanonicalName() + ".class, \"" + field.getName() +
+            "\", this, " + recv + ");";
+    }
+
+    protected String flatWriteStatement (Field field, String recv)
+    {
+        return "com.threerings.io.GenStreamUtil.writeField(" +
+            field.getDeclaringClass().getCanonicalName() + ".class, \"" + field.getName() +
+            "\", this, " + recv + ");";
+    }
+
     protected String toReadObject (Field field)
     {
         Class<?> type = field.getType();
@@ -196,6 +382,9 @@ public class GenStreamableTask extends GenTask
     /** A list of filesets that contain tile images. */
     protected ArrayList<FileSet> _filesets = Lists.newArrayList();
 
+    /** Whether to generate self-contained flattened methods (Android/ART support). */
+    protected boolean _flatten;
+
     protected static final String READ_OPEN =
         "    // from interface Streamable\n" +
         "    public void readObject (ObjectInputStream ins)\n" +
@@ -209,4 +398,23 @@ public class GenStreamableTask extends GenTask
         "        throws IOException\n" +
         "    {\n";
     protected static final String WRITE_CLOSE = "    }\n";
+
+    // fully-qualified signatures for flatten mode so no imports are required in the target file
+    protected static final String FLAT_READ_OPEN =
+        "    // from interface Streamable\n" +
+        "    public void readObject (com.threerings.io.ObjectInputStream ins)\n" +
+        "        throws java.io.IOException, java.lang.ClassNotFoundException\n" +
+        "    {\n";
+    protected static final String FLAT_WRITE_OPEN =
+        "    // from interface Streamable\n" +
+        "    public void writeObject (com.threerings.io.ObjectOutputStream out)\n" +
+        "        throws java.io.IOException\n" +
+        "    {\n";
+
+    /** Matches a pass-through {@code recv.defaultReadObject();} statement (captures indent, recv). */
+    protected static final Pattern DEFAULT_READ =
+        Pattern.compile("(?m)^([ \\t]*)(\\w+)\\.defaultReadObject\\s*\\(\\s*\\)\\s*;[ \\t]*$");
+    /** Matches a pass-through {@code recv.defaultWriteObject();} statement. */
+    protected static final Pattern DEFAULT_WRITE =
+        Pattern.compile("(?m)^([ \\t]*)(\\w+)\\.defaultWriteObject\\s*\\(\\s*\\)\\s*;[ \\t]*$");
 }

tools/src/main/resources/com/threerings/presents/tools.properties

@@ -1,4 +1,5 @@
 gendobj=com.threerings.presents.tools.GenDObjectTask
+genstreamable=com.threerings.presents.tools.GenStreamableTask
 genservice=com.threerings.presents.tools.GenServiceTask
 genreceiver=com.threerings.presents.tools.GenReceiverTask
 instream=com.threerings.presents.tools.InstrumentStreamableTask