mcp: Upgrade conformance test to latest available deployoment (#1021)

Upgrade conformance test to the 0.2.0-alpha.5 version, and differentiate
legacy from 20260728 servers.

Author: guglielmo-san

.github/workflows/conformance.yml

@@ -13,6 +13,9 @@ concurrency:
 permissions:
   contents: read
 
+env:
+  CONFORMANCE_VERSION: "0.2.0-alpha.5"
+
 jobs:
   server-conformance:
     runs-on: ubuntu-latest
@@ -23,19 +26,34 @@ jobs:
         uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
         with:
           go-version: "^1.26"
-      - name: Start everything-server
-        run: |
-          go run ./conformance/everything-server/main.go -http=":3001" &
-          # Wait for the server to be ready.
-          timeout 30 bash -c 'until curl -s http://localhost:3001/mcp; do sleep 0.5; done'
-      - name: "Run conformance tests" 
-        uses: modelcontextprotocol/conformance@a2855b03582a6c0b31065ad4d9af248316ce61a3 # v0.1.15
+      - name: Set up Node.js
+        uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903 # v6.0.0
         with:
-          mode: server
-          url: http://localhost:3001/mcp
-          suite: active
-          expected-failures: ./conformance/baseline.yml
           node-version: 22
+      - name: Build everything-server
+        run: go build -o everything-server ./conformance/everything-server
+      - name: Run conformance tests (stateful, legacy spec versions)
+        run: |
+          ./everything-server -http=":3001" -stateless=false &
+          SERVER_PID=$!
+          trap "kill -9 $SERVER_PID 2>/dev/null || true; wait $SERVER_PID 2>/dev/null || true" EXIT
+          timeout 30 bash -c 'until curl -s http://localhost:3001/mcp > /dev/null; do sleep 0.5; done'
+          npx -y "@modelcontextprotocol/conformance@${CONFORMANCE_VERSION}" server \
+            --url http://localhost:3001/mcp \
+            --suite active \
+            --spec-version 2025-11-25 \
+            --expected-failures ./conformance/baseline.yml
+      - name: Run conformance tests (stateless, 2026-07-28)
+        run: |
+          ./everything-server -http=":3001" -stateless &
+          SERVER_PID=$!
+          trap "kill -9 $SERVER_PID 2>/dev/null || true; wait $SERVER_PID 2>/dev/null || true" EXIT
+          timeout 30 bash -c 'until curl -s http://localhost:3001/mcp > /dev/null; do sleep 0.5; done'
+          npx -y "@modelcontextprotocol/conformance@${CONFORMANCE_VERSION}" server \
+            --url http://localhost:3001/mcp \
+            --suite active \
+            --spec-version 2026-07-28 \
+            --expected-failures ./conformance/baseline.yml
 
   client-conformance:
     runs-on: ubuntu-latest
@@ -46,11 +64,13 @@ jobs:
         uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
         with:
           go-version: "^1.26"
-      - name: "Run conformance tests" 
-        uses: modelcontextprotocol/conformance@a2855b03582a6c0b31065ad4d9af248316ce61a3 # v0.1.15
+      - name: Set up Node.js
+        uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903 # v6.0.0
         with:
-          mode: client 
-          command: go run ./conformance/everything-client
-          suite: core
-          expected-failures: ./conformance/baseline.yml
           node-version: 22
+      - name: Run conformance tests
+        run: |
+          npx -y "@modelcontextprotocol/conformance@${CONFORMANCE_VERSION}" client \
+            --command "go run ./conformance/everything-client" \
+            --suite core \
+            --expected-failures ./conformance/baseline.yml

conformance/everything-server/main.go

@@ -27,7 +27,8 @@ import (
 )
 
 var (
-	httpAddr = flag.String("http", "", "if set, use streamable HTTP at this address, instead of stdin/stdout")
+	httpAddr  = flag.String("http", "", "if set, use streamable HTTP at this address, instead of stdin/stdout")
+	stateless = flag.Bool("stateless", true, "use stateless streamable HTTP mode")
 )
 
 const watchedResourceURI = "test://watched-resource"
@@ -60,7 +61,7 @@ func main() {
 	if *httpAddr != "" {
 		handler := mcp.NewStreamableHTTPHandler(func(*http.Request) *mcp.Server {
 			return server
-		}, nil)
+		}, &mcp.StreamableHTTPOptions{Stateless: *stateless})
 		log.Printf("Conformance server listening at %s", *httpAddr)
 		log.Fatal(http.ListenAndServe(*httpAddr, handler))
 	} else {