Normalize empty notification params to {} (PHP [] → JSON object) + typo fix

[csfh]

Hello,

This PR fixes an interop issues caused by PHP JSON serialization, correctly, of [] (PHP empty array) into [] (JSON empty array). But MCP notifications expect params to be an object, even if it's empty.

Here is the link from the specification.

https://modelcontextprotocol.io/specification/2025-03-26/basic?utm_source=chatgpt.com#notifications

User benefits

• Prevents empty notifications from being rejected due to shape (this is how I discovered this using the MCP Inspector)
• Removes a subtle PHP-specific edge case for users implement MCP with Laravel.

Safety

• This is safe because it only affects the empty case. Non-empty arrays (associative arrays) will be correctly serialized into objects as expected.

Tests

• Added test confirmining that [] params pass.
• Non-empty arrays are unaffected.

I had earlier on discovered a meaningless typo, that I did not intend to bring up, but since I am submitting a PR anyway I figured that would be okay to resolve.

Other options

I do see that the spec allows for params to be omitted entirely, but I consider that a larger and potentially more risky resolution.

{
  jsonrpc: "2.0";
  method: string;
  params?: {
    [key: string]: unknown;
  };
}

AI

I delegated the fix for this to GitHub Copilot. I have reviewed and verified the fix.

[github-actions]

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