chore(server): track ext-apps migration to MCP v2 server SDK

[bokelley]

Context

AdCP uses @modelcontextprotocol/server@2.0.0-beta.4 for its modern per-request MCP adapter, while the canonical @modelcontextprotocol/ext-apps server helpers still target @modelcontextprotocol/sdk v1.29.

Upstream tracking issue: modelcontextprotocol/ext-apps#702

This matters because registerAppTool and registerAppResource provide the canonical MCP Apps types and compatibility behavior, including:

• normalization between _meta.ui.resourceUri and the legacy _meta["ui/resourceUri"] key
• the text/html;profile=mcp-app resource MIME default
• typed tool visibility and resource _meta.ui fields

Relationship to #2368

This does not block shipping the typed custom-tool _meta seam or the follow-on AdCP resource-registration surface. The MCP v2 server already exposes public registerTool and registerResource APIs; AdCP can register resources on each reconstructed per-request server.

The dependency becomes relevant when we want to replace local compatibility types and normalization with the canonical ext-apps implementation.

Follow-up when upstream #702 lands

• Evaluate the released ext-apps v2 server helpers against AdCPs modern adapter.
• Adopt or re-export canonical MCP Apps tool/resource metadata types where compatible.
• Replace redundant local normalization and MIME defaults with canonical helpers.
• Verify nested and legacy resource-URI metadata compatibility.
• Verify app-only tool visibility and resource _meta.ui behavior through tools/list, resources/list, and resources/read.
• Remove any temporary compatibility code or dependencies that are no longer needed.

Refs #2368.

[bokelley]

Triage

Classification: tracking / meta
Bucket(s): library, dependencies
Status: deferred

My take: This is a well-scoped tracking stub with no local implementation possible until modelcontextprotocol/ext-apps#702 ships. Blocking dependency is external; the checklist in the body captures the full follow-up scope. No tracking label exists in this repo — flagging that gap below.

Blocked-on: modelcontextprotocol/ext-apps#702 — resurfaces when upstream ships.

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Triaged by Claude Code. Session: https://claude.ai/code/session_018smRqrbH4GdKXjWmrptRQ8

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Generated by Claude Code