World preview: switch to streaming tile architecture

app/electron/src/session.js

@@ -66,6 +66,12 @@ export class Session {
             if (files.length === 0) {
                 throw new Error("chunker-cli executable is missing!");
             }
+
+            // The dev build directory can contain multiple versioned jars (e.g. an older
+            // chunker-cli-1.17.0.jar left next to chunker-cli-1.18.1.jar). Sort by name using
+            // numeric ordering so we always launch the newest build instead of whichever the OS
+            // happens to list first.
+            files.sort((a, b) => b.name.localeCompare(a.name, undefined, {numeric: true}));
             executable = path.join(cliDirectory, files[0].name);
         }
 
@@ -277,6 +283,12 @@ export class Session {
             case "generate_preview":
                 await this.generatePreview(data.requestId);
                 break;
+            case "request_preview_tiles":
+                await this.requestPreviewTiles(data);
+                break;
+            case "cancel_preview_tiles":
+                await this.cancelPreviewTiles(data);
+                break;
             case "convert":
                 await this.convertWorld(data.outputType, data.requestId, data);
                 break;
@@ -665,12 +677,32 @@ export class Session {
             outputPath: previewOutputPath
         }
 
-        // Send the preview request
-        this.sendToProcess(request, async (response) => {
-            // Use the base64 of the map.bin for output
-            response.output = (await fs.readFile(path.join(previewOutputPath, "map.bin"))).toString("base64");
+        // Send the preview request. The renderer fetches map.bin via session:// URL after
+        // receiving the success response — no base64 payload on the wire.
+        this.sendToProcess(request);
+    }
 
-            return response;
+    requestPreviewTiles(data) {
+        this.sendToProcess({
+            type: "request_preview_tiles",
+            requestId: data.requestId,
+            anonymousId: this._sessionID,
+            world: data.world,
+            lod: data.lod,
+            minTx: data.minTx,
+            minTz: data.minTz,
+            maxTx: data.maxTx,
+            maxTz: data.maxTz
+        });
+    }
+
+    cancelPreviewTiles(data) {
+        this.sendToProcess({
+            type: "cancel_preview_tiles",
+            requestId: data.requestId,
+            anonymousId: this._sessionID,
+            world: data.world,
+            lod: data.lod
         });
     }
 

app/ui/src/api.js

@@ -1,58 +1,62 @@
 let api = {
     connection: undefined,
     replyHandlers: {},
+    listeners: {},
     connect: function (connectHandler) {
         let handlers = {};
 
-        // Connection open handler
         handlers.onopen = function () {
             connectHandler();
         };
 
-        // Connection close handler
         handlers.onclose = function (e) {
             api.connection = undefined;
-            if (e.code === 1000) return; // Don't show error, as it was completed cleanly (and successful!)
+            if (e.code === 1000) return;
             if (e.code === 200) {
-                // Connection closed intentionally (eg. inactive)
-            } else {
-                // Connection closed for other reason, should reconnect?
+                // intentional close
             }
             connectHandler(e.code);
         };
 
-        // Connection message handler
         handlers.onmessage = function (e) {
             let msg = JSON.parse(e.data);
             let requestId = msg.requestId;
-            if (api.replyHandlers[requestId] === undefined) {
-                console.warn("No reply handler found: ", msg);
-            } else {
-                let handler = api.replyHandlers[requestId];
-
-                // Check if handler needs removing
+            let handler = api.replyHandlers[requestId];
+            if (handler !== undefined) {
                 if (msg.continue === undefined || msg.continue === false) {
-                    // Remove as it's done
                     delete api.replyHandlers[requestId];
                 }
-
-                // Call handler
                 handler(msg);
+                return;
+            }
+
+            let typed = api.listeners[msg.type];
+            if (typed && typed.length > 0) {
+                for (let cb of typed) cb(msg);
+                return;
             }
+
+            console.warn("No reply handler or listener found: ", msg);
         };
 
-        // Set connection
         this.connection = window.chunker.connect(handlers);
     },
     send: function (obj, replyHandler) {
-        obj.requestId = crypto.randomUUID();// Generate random id
+        obj.requestId = crypto.randomUUID();
         if (this.connection !== undefined) {
             this.replyHandlers[obj.requestId] = replyHandler;
             this.connection.send(JSON.stringify(obj));
         } else {
             throw Error("Not connected!");
         }
     },
+    addListener: function (type, callback) {
+        if (!this.listeners[type]) this.listeners[type] = [];
+        this.listeners[type].push(callback);
+        return () => {
+            this.listeners[type] = (this.listeners[type] || []).filter(cb => cb !== callback);
+        };
+    },
     isConnected: function () {
         return this.connection !== undefined;
     },
@@ -63,4 +67,4 @@ let api = {
     }
 };
 
-export default api;
+export default api;