docs(mcp): fold the stateless MCP change into the 0.9 migration guide

Retarget the stateless MCP 2026-07-28 migration to ship within 0.9: the
change is source-compatible (no public API or dependency changes), so it
lands as a 0.9 minor rather than a dedicated 0.10 clean break. Remove the
separate 0.10 guide, revert the migration renumbering, and document the
stateless endpoints as a section in the 0.9 guide.

Author: antfubot

docs/content/7.migrations/1.migration-0.10.md

@@ -1,9 +1,9 @@
 ---
 title: 'Migrating to 0.9'
-description: '0.9 removes the compatibility shims deprecated across the 0.7 series and trims the public API of devframe and @devframes/hub. Each change has a drop-in replacement.'
+description: '0.9 removes the compatibility shims deprecated across the 0.7 series, trims the public API of devframe and @devframes/hub, and moves the MCP surface to the stateless MCP 2026-07-28 protocol.'
 ---
 
-0.9 removes the compatibility shims deprecated across the 0.7 series and trims the public API of `devframe` and `@devframes/hub`. Each change has a drop-in replacement.
+0.9 removes the compatibility shims deprecated across the 0.7 series and trims the public API of `devframe` and `@devframes/hub`. Each change has a drop-in replacement. It also moves the [MCP](/adapters/mcp) surface to the stateless [MCP 2026-07-28 protocol](https://modelcontextprotocol.io/specification/2026-07-28) — the devframe API is unchanged; see [The MCP endpoints are stateless](#the-mcp-endpoints-are-stateless).
 
 ## `devframe/adapters/cli` is removed
 
@@ -332,3 +332,23 @@ export const DELETE = (req: Request) => hub.handler(req)
 ```
 
 `@devframes/vite/hub` and `@devframes/nuxt/hub` recommend the native [Vite DevTools](https://devtools.vite.dev) / [Nuxt DevTools](https://devtools.nuxt.com) once (silence with `{ quiet: true }`); `@devframes/next/hub` stays quiet.
+
+## The MCP endpoints are stateless
+
+The [MCP](/adapters/mcp) surface serves the stateless [2026-07-28 protocol](https://modelcontextprotocol.io/specification/2026-07-28). The devframe API you author against — `createMcpServer`, `createMcpFetchHandler`, `mountMcpHttp`, `cli.mcp`, and the agent host — is unchanged; the change is in how the endpoints serve requests on the wire.
+
+- **HTTP** serves each request through the SDK's `createMcpHandler`, building a fresh server per request. There is no `Mcp-Session-Id` and no `initialize` handshake to open a session, so a request reaches any server instance without affinity. A `GET` or `DELETE` (the 2025 session operations) is answered `405`. 2025-era clients keep listing and calling tools and resources through the SDK's stateless legacy path; the live server-push channel for `list_changed` notifications is available to modern clients over the `subscriptions/listen` stream they open.
+- **stdio** serves the connection through the SDK's `serveStdio`, pinning one server instance per connection and negotiating the 2026-07-28 era (falling back to the 2025 handshake for a 2025-era opening).
+- **`devframe connect`** probes each instance with `server/discover` and negotiates the modern era, falling back to the 2025 handshake for a 2025-only instance.
+
+A client that connects to devframe's HTTP endpoint should negotiate the modern era to use the stateless protocol; one left on the default (2025-era) negotiation is still served through the stateless legacy path:
+
+```ts
+import { Client } from '@modelcontextprotocol/client'
+
+const client = new Client(
+  { name: 'my-client', version: '1.0.0' },
+  { versionNegotiation: { mode: 'auto' } },
+)
+await client.connect(transport)
+```

…/content/7.migrations/2.migration-0.9.md …/content/7.migrations/1.migration-0.9.mddocs/content/7.migrations/2.migration-0.9.md renamed to docs/content/7.migrations/1.migration-0.9.md docs/content/7.migrations/2.migration-0.9.md renamed to docs/content/7.migrations/1.migration-0.9.md

@@ -7,8 +7,7 @@ Upgrade guides for devframe and `@devframes/hub`, newest first. Each one lists e
 
 | Version | What changed |
 | ------- | ------------ |
-| [Migrating to 0.10](/migrations/migration-0.10) | Moves the MCP surface to the stateless MCP 2026-07-28 protocol. |
-| [Migrating to 0.9](/migrations/migration-0.9) | Removes the compatibility shims deprecated across the 0.7 series and trims the public API. |
+| [Migrating to 0.9](/migrations/migration-0.9) | Removes the compatibility shims deprecated across the 0.7 series, trims the public API, and moves the MCP surface to the stateless MCP 2026-07-28 protocol. |
 | [Migrating to 0.8](/migrations/migration-0.8) | Makes RPC schemas validator-neutral and runtime-validated, and adds the agent-native MCP API. |
 | [Migrating to 0.7](/migrations/migration-0.7) | Makes `cac` an optional peer and moves json-render into an opt-in package. |
 | [Migrating to 0.6](/migrations/migration-0.6) | Tightens `defineDevframe`'s metadata, replaces the terminal and WebSocket transports, and adds enforced auth. |