Apple's `xcrun mcpbridge` decodes JSON-RPC `id` as an integer only. OMP
mints collision-resistant snowflake strings, so the bridge logs
`mcpbridge.DecodeError Code=1`, never replies, and every request hangs
until it times out (#7053). JSON-RPC 2.0 permits String and Number ids
equally, so both shapes are legal and the string default stays.
Add `requestIdFormat: "string" | "number"` to the shared server config
and honor it in all three transports through one allocator. The string
default is unchanged, so this is inert unless a server opts in.
Verified against Xcode 26.3's bridge: with `"number"`, `initialize`
succeeds and `tools/list` returns all 21 tools; with the default, the
same request times out.
Jérémy Marchand
8560188314