feat: make MCP SDK a peer dependency

[ochafik]

Summary

Makes @modelcontextprotocol/sdk a peer dependency instead of a regular dependency.

Changes:

• Move SDK from dependencies to peerDependencies (^1.20.0)
• Add SDK to devDependencies for local development (^1.24.3)
• Externalize SDK from all build entry points (app, app-bridge, react, server)

Benefits:

• Consumers control their SDK version
• Deduplication when consumer already has SDK installed
• Follows same pattern as react/zod peer dependencies
• Examples already have explicit SDK deps, so they work independently

Testing different SDK versions:

npm install @modelcontextprotocol/sdk@1.20.0  # minimum supported
npm install @modelcontextprotocol/sdk@1.24.3  # latest

🤖 Generated with Claude Code

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/modelcontextprotocol/ext-apps/@modelcontextprotocol/ext-apps@168

commit: 5634b9c

[jonathanhefner]

Seems good. How did you determine the minimum (^1.20.0)?

[ochafik]

Good question! I tested earlier versions and found:

• SDK <1.24.0: Fails with Zod 4 type incompatibilities (the SDK bundles its own Zod, and the types don't align with our Zod 4 peer dep)
• SDK 1.24.0+: Works correctly

Updated the peer dep to ^1.24.0 to ensure compatibility. The examples already use ^1.22.0 in their own deps, so they'll get upgraded automatically.