UAN-023 named-client and host availability probe
Date: 2026-10-03 UTC. Isolated source commit: 076b4197e49997da190389d9e247521baa3bab50. Host: research, macOS 27.0 build 26A425, Node 25.9.0, npm 11.12.1. These observations do not complete UAN-023 or the v1 release matrix.
Pinned named MCP client over HTTP
The independent client was the official MCP Inspector CLI, pinned to @modelcontextprotocol/inspector@2.8.0. It connected with Streamable HTTP to the packed E09 example's actual loopback server. This is a real named client and real HTTP transport; the server/data and identity policy remain local fixtures. No commercial service or external network endpoint was tested.
Reproduce from this checkout:
npm ci --ignore-scripts --no-audit --no-fund
npm run build
npm run example:e09
node test/uan023-inspector-client.mjs
The manual probe starts the E09 server on 127.0.0.1, invokes the Inspector CLI four times with a 45-second per-call timeout, asserts protocol outcomes, and closes the server. It uses npx --yes @modelcontextprotocol/inspector@2.8.0; no credential is passed.
Observed results:
| Probe | Inspector result |
|---|---|
tools/list |
Exit 0; exactly one named album-lookup tool with input/output schemas and a ui://uppercut/album-explorer.html resource reference |
tools/call --app-info |
Exit 0; hasApp: true, resource MIME text/html;profile=mcp-app |
tools/call with {"slug":"first-light"} |
Exit 0; text and structuredContent.result both represent the found album |
tools/call with {"slug":"blocked-album"} |
Exit 5; isError: true and no successful value |
The standalone E09 packaging/build/tests also passed (3/3). The probe script is the exact assertion source. Its .exported E09 dependency is intentionally generated by npm run example:e09, not checked in. The result expands the prior SDK-only fixture evidence to a separately distributed named client CLI. Inspector CLI app metadata inspection does not demonstrate rendering or interaction in an MCP Apps host.
Browser and MCP Apps host boundary
Installed Google Chrome 154.0.8037.95 was probed in a headless, no-focus session without an origin-trial token or experimental flag. document.modelContext and its registerTool member both evaluated as undefined on a blank page. This shows the default local Chrome session did not expose native WebMCP; it does not test a supported WebMCP agent host. Chrome's WebMCP origin-trial notice describes opt-in access. The package's ordinary-site fallback was covered by earlier simulated/browser fixtures, not by this blank-page probe.
The Inspector CLI read App resource metadata and called the tool, but no Inspector web UI or other MCP Apps iframe host was opened. App rendering, host-mediated UI actions, browser sandbox/CSP enforcement, and consent behavior remain unverified. No author-independent human or clean-context Astro adoption was performed. UAN-023 cannot be marked complete from this slice.
No Windows foreground UI was used. No external credential, private package, deployment, or npm publish was involved.