feat: add world voxel snapshot forwarding

Collect chunk voxel data from the bot world and stream snapshot,
chunk, and unwatch messages through the forward protocol.

tests/forward_integration.test.mjs

@@ -484,7 +484,7 @@ test('execute_function traverses the relay with boolean results, permission chec
     assert.equal(success_data(await ack(web.socket, 'relay_request', request('execute_function', payload))), false);
 });
 
-test('actual manager serves snapshots, logs and chat without forwarding bot events', async t => {
+test('actual manager pushes lifecycle changes to snapshot readers without exposing other bot events', async t => {
     const f = await real_fixture(t); const s = scope(); await f.open(s);
     const manager = f.manager(s); const cmd = f.cmd(s);
     assert.deepEqual(await manager.ensure(cmd), success({...s, node_ready: true, lease_expires_at: cmd.expires_at}));
@@ -497,21 +497,29 @@ test('actual manager serves snapshots, logs and chat without forwarding bot even
     assert.deepEqual(Object.keys(absent).sort(), ['bot_id', 'bot_status', 'captured_at', 'context_exists', 'context_generation', 'seq', 'stream_id']);
     assert.equal(absent.context_exists, false); assert.equal(absent.context_generation, null); assert.equal(absent.bot_status, 'offline');
     code(await ack(web.socket, 'relay_request', request('bot.chat', {message: 'hello'})), 'NO_CONTEXT');
-    let leaks = 0; other.socket.on('relay_request', () => leaks++); other.socket.on('bot_event', () => leaks++);
+    let leaks = 0; other.socket.on('relay_request', () => leaks++);
+    const reader_events = []; other.socket.on('bot_event', event => reader_events.push(event));
     assert.equal((await ack(web.socket, 'relay_request', request('bot.subscribe', {events: ['status_update', 'log', 'message', 'bot_error']}))).status, 'success');
     const events = []; web.socket.on('bot_event', value => events.push(value));
     const bot = online_context();
+    const initial_status = received(other.socket, 'bot_event', event => event.payload.status === 'online');
     f.source(s.bot_id).set(bot);
+    await initial_status;
     const snapshot = success_data(await ack(web.socket, 'relay_request', request()));
     assert.equal(snapshot.context_exists, true); assert.equal(snapshot.bot_status, 'online');
     assert.equal(snapshot.stream_id, absent.stream_id); assert.ok(snapshot.context_generation);
     for (const state of ['offline', 'ready', 'connecting', 'online', 'disconnecting', 'reconnecting']) {
+        const pushed = received(web.socket, 'bot_event', event => event.payload.status === state);
+        const reader_pushed = received(other.socket, 'bot_event', event => event.payload.status === state);
         bot.bot_status = state; bot.emit('status_update', state);
+        await Promise.all([pushed, reader_pushed]);
         const current = success_data(await ack(web.socket, 'relay_request', request()));
         assert.equal(current.context_exists, true);
         assert.equal(current.bot_status, state); assert.equal(current.context_generation, snapshot.context_generation);
     }
+    const back_online = received(web.socket, 'bot_event', event => event.payload.status === 'online');
     bot.bot_status = 'online'; bot.emit('status_update', 'online');
+    await back_online;
     const log_packet = received(web.socket, 'bot_log');
     const metadata = {hoverEvent: {action: 'show_text', value: '悬停说明'},
         clickEvent: {action: 'suggest_command', value: '/help'}, insertion: 'Alex'};
@@ -555,8 +563,9 @@ test('actual manager serves snapshots, logs and chat without forwarding bot even
     bot.emit('error', new Error('SECRET stack'));
     assert.equal(JSON.stringify({snapshot, logs}).includes('SECRET'), false);
     await ack(other.socket, 'relay_request', request()); assert.equal(leaks, 0);
-    assert.deepEqual(events, []);
-    assert.equal(f.packets.some(packet => packet.event === 'bot_event'), false);
+    assert.ok(events.length >= 7 && reader_events.length >= 7);
+    assert.ok([...events, ...reader_events].every(event => event.name === 'status_update'));
+    assert.ok(f.packets.some(packet => packet.event === 'bot_event'));
     manager.stop(); assert.equal(f.source(s.bot_id).count, 0); assert.equal(bot.listenerCount('log'), 0);
 });
 
@@ -626,16 +635,20 @@ test('one Node manager isolates multiple Bot sessions and observes stop/start wi
     await ack(web_a.socket, 'relay_request', request('bot.chat', {message: 'a'}));
     await ack(web_b.socket, 'relay_request', request('bot.chat', {message: 'b'}));
     assert.deepEqual(bot_a.sent, ['a']); assert.deepEqual(bot_b.sent, ['b']);
+    const stopped = received(web_a.socket, 'bot_event', event => event.payload.status === 'offline');
     f.source(a.bot_id).set(undefined);
+    await stopped;
     const absent = success_data(await ack(web_a.socket, 'relay_request', request()));
     assert.equal(absent.bot_status, 'offline'); assert.equal(absent.context_generation, null);
     const replacement = online_context();
+    const started = received(web_a.socket, 'bot_event', event => event.payload.status === 'online');
     f.source(a.bot_id).set(replacement);
+    await started;
     const after = success_data(await ack(web_a.socket, 'relay_request', request()));
     assert.equal(after.stream_id, before.stream_id); assert.notEqual(after.context_generation, before.context_generation);
     assert.equal(web_a.socket.connected, true); assert.equal(f.node_sockets.length, 2);
     assert.equal(events_b.length, 0);
-    assert.equal(events_a.length, 0);
+    assert.deepEqual(events_a.map(event => event.payload.status), ['offline', 'online']);
     assert.equal(bot_a.listenerCount('log'), 0);
 });