refactor: move the schema source modules into @modelcontextprotocol/core (#2477)

docs/advanced/wire-schemas.md

@@ -1,6 +1,7 @@
 ---
 shape: how-to
 ---
+
 # Wire schemas
 
 `@modelcontextprotocol/core` exports the **wire schemas** — the exact Zod constants the SDK validates protocol and OAuth payloads against — for code that holds raw JSON instead of SDK objects.
@@ -56,7 +57,7 @@ These are the `*Schema` constants v1 exported from `@modelcontextprotocol/sdk/ty
 
 If you build with `McpServer` or `Client`, skip this package: [tools](../servers/tools.md) arrive in your handler already validated, and [tool calls](../clients/calling.md) come back as typed results. Reach for `@modelcontextprotocol/core` when nothing stands between you and the JSON — gateways, proxies, test harnesses, [worker fleets](./gateway.md).
 
-Install it separately (`npm install @modelcontextprotocol/core`) — `@modelcontextprotocol/server` and `@modelcontextprotocol/client` keep a Zod-free public surface and never depend on it. The package is runtime-neutral; `zod` is its only dependency.
+`@modelcontextprotocol/server` and `@modelcontextprotocol/client` keep a Zod-free public surface, but they resolve their shared schema graph from this package at runtime, so it already arrives transitively in your tree. Add it to your own `dependencies` (`npm install @modelcontextprotocol/core`) when you import from it directly. The package is runtime-neutral; `zod` is its only dependency.
 
 ## Pick the schema for the message you hold
 

docs/get-started/packages.md

@@ -66,7 +66,7 @@ Four adapters exist: `@modelcontextprotocol/node` for Node's built-in `http` ser
 
 ## Reach for `core` only to validate raw wire JSON
 
-`@modelcontextprotocol/core` exports the Zod schema constants the SDK validates protocol payloads against, for code that handles raw JSON-RPC payloads itself — gateways, proxies, log pipelines. Neither `server` nor `client` exports a Zod schema, and the matching TypeScript types ship with both, so if you only call `registerTool` and `callTool` you never install it. [Wire schemas](../advanced/wire-schemas.md) is the how-to.
+`@modelcontextprotocol/core` exports the Zod schema constants the SDK validates protocol payloads against, for code that handles raw JSON-RPC payloads itself — gateways, proxies, log pipelines. Neither `server` nor `client` exports a Zod schema, and the matching TypeScript types ship with both, so if you only call `registerTool` and `callTool` you never import it directly — it arrives transitively, since `server` and `client` resolve their shared schema graph from it at runtime. [Wire schemas](../advanced/wire-schemas.md) is the how-to.
 
 ## Leave `server-legacy` and `codemod` to the migration guide
 

docs/migration/upgrade-to-v2.md

@@ -848,7 +848,7 @@ hierarchy also exposes the same check as an explicit static guard
 TypeScript — use whichever style your codebase prefers; both read the same brand.
 Fine print (applies equally to `instanceof` and `isInstance`):
 
-- **Version skew** — matching needs *both* copies at a brand-aware release; against an
+- **Version skew** — matching needs _both_ copies at a brand-aware release; against an
   older copy, behavior degrades to plain prototype `instanceof` (false across bundles).
   During mixed-version rollouts, recognize errors without class identity: match
   `error.name` plus the class's discriminant field (`code`, `status`), or reconstruct
@@ -1325,8 +1325,9 @@ if (CallToolResultSchema.safeParse(value).success) { ... }
 
 `@modelcontextprotocol/core` is the canonical home for the spec's Zod schema constants
 (and the OAuth/OpenID metadata schemas). It is runtime-neutral (its only dependency is
-`zod`) and is **not** required by `client` / `server` — install it only if you import the
-raw schemas directly.
+`zod`) and arrives transitively as the shared runtime schema graph of `client` /
+`server` — add it to your own `dependencies` only when you import the raw schemas
+directly.
 
 If you would rather keep your project Zod-free, the **`isSpecType` / `specTypeSchemas`**
 alternatives are exported from `@modelcontextprotocol/client` and `…/server`: