Register VM service with DTD #8436

helin24 · 2025-08-08T16:31:16Z

Addresses #8261

How to test that this works:

Set up an MCP agent - Jake recommended using gemini-cli as the easiest option
With this change in our plugin, start running an app from Android Studio/IJ
Copy the DTD URI (Find Action > Dart: Copy DTD URI to Clipboard)
Start agent and ask for a widget tree of your running app. It should ask for the DTD URI and then provide a widget tree; see below.

helinx-mac:flutter helinx$ gemini

 ███            █████████  ██████████ ██████   ██████ █████ ██████   █████ █████
░░░███         ███░░░░░███░░███░░░░░█░░██████ ██████ ░░███ ░░██████ ░░███ ░░███
  ░░░███      ███     ░░░  ░███  █ ░  ░███░█████░███  ░███  ░███░███ ░███  ░███
    ░░░███   ░███          ░██████    ░███░░███ ░███  ░███  ░███░░███░███  ░███
     ███░    ░███    █████ ░███░░█    ░███ ░░░  ░███  ░███  ░███ ░░██████  ░███
   ███░      ░░███  ░░███  ░███ ░   █ ░███      ░███  ░███  ░███  ░░█████  ░███
 ███░         ░░█████████  ██████████ █████     █████ █████ █████  ░░█████ █████
░░░            ░░░░░░░░░  ░░░░░░░░░░ ░░░░░     ░░░░░ ░░░░░ ░░░░░    ░░░░░ ░░░░░

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╭────────────────────────────────────────────────────────╮
│  > can you show me the widget tree of my running app?  │
╰────────────────────────────────────────────────────────╯

✦ I can do that, but I need the Dart Tooling Daemon URI first. Please paste it here. If you're using VS Code or Android Studio, you can find it by searching for the "Copy DTD Uri to clipboard" action.

╭───────────────────────────────────────╮
│  > ws://127.0.0.1:53745/DI-z9OH3XB0=  │
╰───────────────────────────────────────╯

 ╭────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
 │ ✔  connect_dart_tooling_daemon (dart MCP Server) {"uri":"ws://127.0.0.1:53745/DI-z9OH3XB0="}                                                                                                                       │
 │                                                                                                                                                                                                                    │
 │    Connection succeeded                                                                                                                                                                                            │
 ╰────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
 ╭────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
 │ ✔  get_widget_tree (dart MCP Server) {}                                                                                                                                                                            │
 │                                                                                                                                                                                                                    │
 │    {"description":"[root]","shouldIndent":true,"widgetRuntimeType":"RootWidget","valueId":"inspector-0","children":[{"description":"MyApp","shouldIndent":true,"widgetRuntimeType":"MyApp","valueId":"inspector-1  │
 │    ","createdByLocalProject":true,"children":[{"description":"MaterialApp","shouldIndent":true,"widgetRuntimeType":"MaterialApp","valueId":"inspector-2","createdByLocalProject":true,"children":[{"description":  │
 │    "MyHomePage","shouldIndent":true,"widgetRuntimeType":"MyHomePage","valueId":"inspector-3","createdByLocalProject":true,"children":[{"description":"Scaffold","shouldIndent":true,"widgetRuntimeType":"Scaffold  │
 │    ","valueId":"inspector-4","createdByLocalProject":true,"children":[{"description":"Center","shouldIndent":true,"widgetRuntimeType":"Center","valueId":"inspector-5","createdByLocalProject":true,"children":[{  │
 │    "description":"Column","shouldIndent":true,"widgetRuntimeType":"Column","valueId":"inspector-8","createdByLocalProject":true,"children":[{"description":"Text","shouldIndent":true,"widgetRuntimeType":"Text",  │
 │    "valueId":"inspector-11","createdByLocalProject":true,"textPreview":"You have pushed the button this many times test                                                                                            │
 │    2:","children":[]},{"description":"Text","shouldIndent":true,"widgetRuntimeType":"Text","valueId":"inspector-12","createdByLocalProject":true,"textPreview":"0","children":[]}]}]},{"description":"AppBar","sh  │
 │    ouldIndent":true,"widgetRuntimeType":"AppBar","valueId":"inspector-6","createdByLocalProject":true,"children":[{"description":"Text","shouldIndent":true,"widgetRuntimeType":"Text","valueId":"inspector-9","c  │
 │    reatedByLocalProject":true,"textPreview":"Flutter Demo Home                                                                                                                                                     │
 │    Page","children":[]}]},{"description":"FloatingActionButton","shouldIndent":true,"widgetRuntimeType":"FloatingActionButton","valueId":"inspector-7","createdByLocalProject":true,"children":[{"description":"I  │
 │    con","shouldIndent":true,"widgetRuntimeType":"Icon","valueId":"inspector-10","createdByLocalProject":true,"children":[]}]}]}]}]}]}]}                                                                            │
 ╰────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
✦  - [root]
       - MyApp
           - MaterialApp
               - MyHomePage
                   - Scaffold
                       - Center
                           - Column
                               - Text: "You have pushed the button this many times test 2:"
                               - Text: "0"
                       - AppBar
                           - Text: "Flutter Demo Home Page"
                       - FloatingActionButton
                           - Icon

helin24 · 2025-08-08T16:31:35Z

CC @jakemac53

jakemac53 · 2025-08-08T16:58:31Z

src/io/flutter/run/daemon/FlutterApp.java

@@ -738,6 +746,12 @@ public void onAppStarting(DaemonEvent.AppStarting event) {
  @Override
  public void onAppDebugPort(@NotNull DaemonEvent.AppDebugPort debugInfo) {
    app.setWsUrl(debugInfo.wsUri);
+    this.appVmServiceUri = debugInfo.wsUri;


Do we get any sort of identifier that we can use as a map key that we can look up when we get the app stopped event for this particular app?

While the MCP server today only supports one connected app, we do want to have it support multiple in the future, so ideally the IDE plugins wouldn't be assuming just one.

IJ can register multiple apps to DTD. There's an app name that's a unique identifier, or the VM service URI is unique too.

This is an example of the params we send with two apps running at the same time:

2025-08-08 09:28:04 io.flutter.run.daemon.FlutterAppDaemonEventListener [INFO ] Successful request ConnectedApp.registerVmService to DTD with params: {"uri":"ws://127.0.0.1:50489/m1aDg3zyHq4=/ws","name":"752c8ff1-86dd-4c91-abab-825747059057"} 2025-08-08 09:29:33 io.flutter.run.daemon.FlutterAppDaemonEventListener [INFO ] Successful request ConnectedApp.registerVmService to DTD with params: {"uri":"ws://127.0.0.1:51041/iUbSRQCLBfg=/ws","name":"65328744-2368-46bf-9e23-70066b219342"}

The unregisterVmService takes the URI as a param also, so I imagine you would use that as the key?

pq · 2025-08-10T17:05:39Z

/fyi @DanTup who did the analogous work for VS Code.

pq

Awesome! 🎉

src/io/flutter/run/daemon/FlutterApp.java

pq · 2025-08-10T17:08:56Z

src/io/flutter/run/daemon/FlutterApp.java

+    final JsonObject params = new JsonObject();
+    params.addProperty("uri", debugInfo.wsUri);
+    params.addProperty("name", debugInfo.appId);
+    sendDtdRequest("ConnectedApp.registerVmService", params);


I'm not sure how we want to test this (And I'd love to get your thoughts), but in anticipation, maybe we should introduce some constants somewhere?

Yes, for now I can add these methods as constants. Maybe a separate file that links to DTD documentation would be helpful.

I haven't thought much about testing; I suppose one part would be testing dtdService.sendRequest in the Dart plugin. And ultimately integration testing in the Dart plugin.

src/io/flutter/run/daemon/FlutterApp.java

helin24 · 2025-08-11T17:02:18Z

Some clean up in #8442

pq · 2025-08-11T17:27:37Z

Awesome. Thanks for following up!

helin24 · 2025-08-11T17:46:52Z

I added some notes above on how to test this

Register VM service with DTD

c6bbcca

helin24 requested review from pq and jwren August 8, 2025 16:31

jakemac53 reviewed Aug 8, 2025

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jwren approved these changes Aug 8, 2025

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helin24 merged commit 35796f6 into flutter:master Aug 8, 2025
7 checks passed

helin24 deleted the mcp branch August 8, 2025 17:14

pq reviewed Aug 10, 2025

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