MCP Apps Plumbing #6286

DOsinga · 2025-12-26T14:26:41Z

Summary

Hook the client up to the actual sever. Works now with at least some MCP servers

Copilot

Pull request overview

This PR connects the desktop client to the actual server for MCP Apps functionality, replacing mock data with real API calls.

Adds sessionId prop threading from GooseMessage through ToolCallWithResponse to McpAppRenderer
Implements dynamic resource fetching via readResource API
Enables MCP apps to call tools and read resources through the backend

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
ui/desktop/src/components/GooseMessage.tsx	Passes sessionId to ToolCallWithResponse component for API authentication
ui/desktop/src/components/ToolCallWithResponse.tsx	Adds maybeRenderMCPApp helper that extracts resourceUri from tool metadata and conditionally renders MCP apps
ui/desktop/src/components/McpApps/McpAppRenderer.tsx	Replaces static resource prop with dynamic fetching via readResource API; implements tools/call and resources/read handlers for guest app requests

Copilot · 2025-12-26T14:30:31Z

ui/desktop/src/components/McpApps/McpAppRenderer.tsx

+        if (response.data) {
+          setResourceHtml(response.data.html);
+          // TODO: Extract CSP from resource metadata when backend supports it
+          // For now, CSP will be null and the proxy will use default restrictions
+        }
+      } catch (err) {


The useEffect is missing proper error handling for the case when response.data is null or undefined. If the API returns a successful response but with null data, setResourceHtml will be called with undefined, but no error state will be set. Consider adding a check and setting an error if data is missing.

Suggested change

if (response.data) {

setResourceHtml(response.data.html);

// TODO: Extract CSP from resource metadata when backend supports it

// For now, CSP will be null and the proxy will use default restrictions

}

} catch (err) {

if (response.data && typeof response.data.html === 'string') {

setResourceHtml(response.data.html);

setError(null);

// TODO: Extract CSP from resource metadata when backend supports it

// For now, CSP will be null and the proxy will use default restrictions

} else {

setResourceHtml(null);

setError('Resource data is missing or invalid');

}

} catch (err) {

setResourceHtml(null);

Copilot · 2025-12-26T14:30:32Z

ui/desktop/src/components/ToolCallWithResponse.tsx

+        toolInput={{ arguments: toolCall.arguments }}
+        extensionName={extensionName}
+        sessionId={sessionId}
+        append={append}


The toolResult prop is not being passed to McpAppRenderer. This will prevent the guest app from receiving tool result notifications via the ui/notifications/tool-result method. Consider passing the toolResult by extracting it from resultWithMeta.value, which should match the ToolResult type expected by the component.

Suggested change

append={append}

append={append}

toolResult={value}

Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated 5 comments.

Copilot · 2025-12-30T16:48:54Z

ui/desktop/src/components/McpApps/useSandboxBridge.ts


        if (msg.method === 'ui/notifications/initialized') {
          setIsGuestInitialized(true);
+          console.log('initialized -> True');


Console.log statement should be removed before merging to production.

Copilot · 2025-12-30T16:48:55Z

ui/desktop/src/components/McpApps/McpAppRenderer.tsx

+          return {
+            content: response.data?.content || [],
+            isError: response.data?.is_error || false,
+            structuredContent: (response.data as any)?.structured_content,


Using 'as any' bypasses type safety. Consider defining a proper type for structured_content in the response type or use a more specific type assertion.

Suggested change

return {

content: response.data?.content || [],

isError: response.data?.is_error || false,

structuredContent: (response.data as any)?.structured_content,

type ToolsCallStructuredContent = McpMethodResponse['tools/call']['structuredContent'];

const structuredContent =

(response.data as { structured_content?: ToolsCallStructuredContent } | undefined)

?.structured_content;

return {

content: response.data?.content || [],

isError: response.data?.is_error || false,

structuredContent,

Copilot · 2025-12-30T16:48:55Z

ui/desktop/src/components/McpApps/useSandboxBridge.ts


  useEffect(() => {
    setIsGuestInitialized(false);
+    console.log('initialized -> False');


Console.log statement should be removed before merging to production.

Copilot · 2025-12-30T16:48:55Z

ui/desktop/src/components/McpApps/useSandboxBridge.ts

  }, [resourceUri]);

  const sendToSandbox = useCallback((message: JsonRpcMessage) => {
+    console.log('>>>', message);


Console.log statement should be removed before merging to production.

Copilot · 2025-12-30T16:48:56Z

ui/desktop/src/components/McpApps/useSandboxBridge.ts


  const handleJsonRpcMessage = useCallback(
    async (data: unknown) => {
+      console.log('jsonResponse', data);


Console.log statement should be removed before merging to production.

aharvard · 2026-01-02T18:12:06Z

ui/desktop/src/components/sessions/SessionViewComponents.tsx

Does this file change need to be part of this PR?

not really; we're dragging in session-ids into sessionviews and so this would have to maybe updated but then it is not used

aharvard

Very good! Confirmed it's working with/ my demo MCP App!

michaelneale · 2026-01-04T16:54:38Z

nice - cli code isn't entirely happy: error[E0063]: missing field tool_meta in initializer of goose::conversation::message::ToolRequest
Error: --> crates/goose-cli/src/session/export.rs:1244:28
|
1244 | let tool_request = ToolRequest {
| ^^^^^^^^^^^ missing tool_meta

is best way to test it what @aharvard did?

michaelneale · 2026-01-04T16:56:09Z

crates/goose/src/agents/extension_manager.rs

-                                icons: None,
-                                title: None,
-                                meta: None,
+                                icons: tool.icons,


huh - so will show the tool it is adding?

no, this is just for completion sake. we're not really using icons as far as I can tell, but dropping these values on the floor can only be bad :)

michaelneale · 2026-01-04T16:56:53Z

ui/desktop/src/api/types.gen.ts


 export type ReadResourceResponse = {
-    html: string;
+    _meta?: {


yeah this seems a reasonable extension to what I remember from mcp ui, nice, a generalisation for apps

aharvard · 2026-01-05T15:05:58Z

is best way to test it what @aharvard did?

@michaelneale if you want to give it a spin...

endpoint: https://mcp-app-bench.onrender.com/mcp

prompt: "run mcp app bench"

jamadeo · 2026-01-05T18:13:16Z

crates/goose/src/agents/extension_manager.rs

-                    cancellation_token.clone(),
-                    true,
-                )
+            let read_result = self


not your code but if thing.is_some() { ... thing.unwrap() ... } should be an if let Some(inner) = thing {...

jamadeo · 2026-01-05T18:19:10Z

ui/desktop/src/components/ToolCallWithResponse.tsx

+
+  let toolResult: CallToolResponse | undefined;
+  if (toolResponse) {
+    const resultWithMeta = toolResponse.toolResult as ToolResultWithMeta;


can we type this properly?

If you see a way? I've been going back and forth here, but toolResponse comes through the API from the rcmp classes which have a hard to time getting converted to proper typescript, so we end up with something semi-typed that we cast

WIP

b723d43

DOsinga requested review from aharvard and Copilot December 26, 2025 14:26

Copilot started reviewing on behalf of DOsinga December 26, 2025 14:27 View session

Copilot AI reviewed Dec 26, 2025

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Douwe Osinga added 3 commits December 26, 2025 11:59

Clean up more

8e31508

WIP

01a601b

Clean up the types

288f975

Copilot AI review requested due to automatic review settings December 30, 2025 16:45

Copilot started reviewing on behalf of DOsinga December 30, 2025 16:46 View session

Copilot AI reviewed Dec 30, 2025

View reviewed changes

Douwe Osinga added 2 commits December 30, 2025 16:04

Clean up

971b629

More simplification

6dc5e59

DOsinga changed the title ~~WIP~~ MCP Apps Plumbing Dec 30, 2025

aharvard reviewed Jan 2, 2026

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aharvard approved these changes Jan 2, 2026

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michaelneale reviewed Jan 4, 2026

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Douwe Osinga added 2 commits January 5, 2026 10:03

Clippy

abc1307

Merge branch 'main' into mcp-apps-plumbing

ac2fe0b

DOsinga merged commit 85aee9c into main Jan 5, 2026
20 checks passed

DOsinga deleted the mcp-apps-plumbing branch January 5, 2026 15:34

jamadeo reviewed Jan 5, 2026

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github-actions bot mentioned this pull request Jan 6, 2026

chore(release): release version 1.19.0 (minor) #6344

Merged

BrewTestBot mentioned this pull request Jan 6, 2026

block-goose-cli 1.19.0 Homebrew/homebrew-core#261531

Merged

MCP Apps Plumbing #6286

MCP Apps Plumbing #6286

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DOsinga commented Dec 26, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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DOsinga commented Dec 26, 2025 •

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