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test: add an MCP App showcase config to reproduce and verify #1859

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The `mcp_app_demo` tool and `mcp_app_demo_widget` UI resource presets already
existed in the preset registry, but no config wired them into a server — so
there was no runnable way to reach a rendered MCP App, and therefore no way to
exercise the sandbox proxy path that #1859 broke.

`mcp-app-http.json` composes the two over plain streamable-HTTP. With it, the
Apps tab renders a real widget and the packaging bug is reproducible on demand:
without clients/web/static in the tarball the widget area shows "Sandbox not
loaded: ENOENT … /clients/web/static/sandbox_proxy.html" instead.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XAR2Nr9kXbrywFNUVoTe9F
This commit is contained in:
cliffhall 2026-08-05 17:59:09 -04:00
commit 28a21c5e08
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9
README.md
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@ -132,6 +132,7 @@ Each config below is a ready-made server for exercising one feature by hand. Loa
| Config | Demonstrates | Issue |
| ----------------------------------------- | -------------------------------------------------- | ---------------------------------------------------------------------- |
| `mcp-app-http.json` | An MCP App (UI resource + app tool) in the Apps tab | [#1859](https://github.com/modelcontextprotocol/inspector/issues/1859) |
| `modern-mrtr-http.json` | A single MRTR round-trip | — |
| `mrtr-showcase-http.json` | Every MRTR preset in one server | — |
| `modern-network-http.json` | Network tab: `Mcp-*` headers + error taxonomy | [#1628](https://github.com/modelcontextprotocol/inspector/issues/1628) |
@ -142,6 +143,14 @@ Each config below is a ready-made server for exercising one feature by hand. Loa
| `subscriptions-{legacy,modern}-http.json` | Resource subscriptions, both eras | [#1630](https://github.com/modelcontextprotocol/inspector/issues/1630) |
| `tasks-{legacy,modern}-http.json` | Tasks, both eras | [#1631](https://github.com/modelcontextprotocol/inspector/issues/1631) |
#### MCP Apps
`mcp-app-http.json` serves the `mcp_app_demo` tool (`_meta.ui.resourceUri`) alongside its `mcp_app_demo_widget` UI resource, so the **Apps** tab has a real App to render. It is a plain streamable-HTTP server — connect with the **default (legacy)** protocol era, not Modern.
Open the Apps tab, select `mcp_app_demo`, give it a title and click **Open App**: the widget renders inside the sandbox iframe and exercises the host-side UI protocol surface — host-context render, `size-changed`, `ui/message`, and a log line into the **App logs** panel. Because the widget is served through the sandbox proxy page, this config is also what reproduces [#1859](https://github.com/modelcontextprotocol/inspector/issues/1859) (a missing `clients/web/static/sandbox_proxy.html` surfaces here as a "Sandbox not loaded" message in place of the widget) — a failure that only ever appeared in an installed package, never in the repo.
For the scripted version of the same flow (`--app-info` probe → deep link → rendered widget), see [Reviewing an MCP App](./docs/mcp-app-review.md).
#### MRTR
`modern-mrtr-http.json` serves the `mrtr_confirm` tool (preset `mrtr_confirm`, `createMrtrTool`) over the modern leg. Its handler returns `inputRequired(...)` embedding a form elicitation, so invoking it produces a real round-trip: `input_required` → the client fulfils the embedded elicitation and retries with a new id → `complete`.

12
test-servers/configs/mcp-app-http.json Normal file
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@ -0,0 +1,12 @@
{
"serverInfo": {
"name": "mcp-app-showcase",
"version": "1.0.0"
},
"tools": [{ "preset": "echo" }, { "preset": "mcp_app_demo" }],
"resources": [{ "preset": "mcp_app_demo_widget" }],
"transport": {
"type": "streamable-http",
"port": 3130
}
}