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mcp: add 2026-07-28 to the supported protocol versions (#1020)

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This PR adds the protocol version `2026-07-28` to the list of supported
protocol versions and fixes legacy tests hardcoding the legacy protocol
version for those use cases.
This commit is contained in:
Guglielmo Colombo 2026-06-24 12:02:56 +02:00 • committed by GitHub
commit 7f4aa4a0ce
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GPG key ID: B5690EEEBB952194
1 changed files with 355 additions and 218 deletions
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62
mcp/client_test.go
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@ -10,7 +10,6 @@ import (
"context"
"fmt"
"log/slog"
"slices"
"sync/atomic"
"testing"
@ -644,13 +643,6 @@ func TestClientCapabilitiesOverWire(t *testing.T) {
// don't overlap with the SDK. The test then asserts the resulting session
// state and whether the legacy initialize handshake ran.
func TestClientConnectDiscover(t *testing.T) {
// Temporarily enable 2026-07-28 support in the SDK for this test
oldSupported := supportedProtocolVersions
supportedProtocolVersions = append([]string{protocolVersion20260728}, supportedProtocolVersions...)
t.Cleanup(func() {
supportedProtocolVersions = oldSupported
})
const otherVersionsOnly = "1999-01-01"
tests := []struct {
@ -686,7 +678,7 @@ func TestClientConnectDiscover(t *testing.T) {
return nil, jsonrpc2.ErrMethodNotFound
},
wantInitialize: true,
wantVersion: latestProtocolVersion,
wantVersion: protocolVersion20251125,
},
{
name: "unsupported protocol version falls back to initialize",
@ -697,7 +689,7 @@ func TestClientConnectDiscover(t *testing.T) {
}
},
wantInitialize: true,
wantVersion: latestProtocolVersion,
wantVersion: protocolVersion20251125,
},
{
name: "no overlapping supported version falls back to initialize",
@ -709,7 +701,7 @@ func TestClientConnectDiscover(t *testing.T) {
}, nil
},
wantInitialize: true,
wantVersion: latestProtocolVersion,
wantVersion: protocolVersion20251125,
},
}
@ -771,10 +763,6 @@ func TestClientConnectDiscover(t *testing.T) {
// request sent by Client.Connect carries the SEP-2575 per-request _meta triple:
// protocolVersion, clientInfo, and clientCapabilities.
func TestClientConnectDiscover_RequestContents(t *testing.T) {
orig := supportedProtocolVersions
supportedProtocolVersions = append([]string{protocolVersion20260728}, slices.Clone(orig)...)
t.Cleanup(func() { supportedProtocolVersions = orig })
ctx := context.Background()
type captured struct {
@ -850,10 +838,6 @@ func TestClientConnectDiscover_RequestContents(t *testing.T) {
func TestInMemory_E2E_DiscoverSuccess(t *testing.T) {
ctx := context.Background()
orig := supportedProtocolVersions
supportedProtocolVersions = append([]string{protocolVersion20260728}, slices.Clone(orig)...)
t.Cleanup(func() { supportedProtocolVersions = orig })
server := NewServer(&Implementation{Name: "stdio-like-server", Version: "v1"}, nil)
ct, st := NewInMemoryTransports()
ss, err := server.Connect(ctx, st, nil)
@ -889,15 +873,11 @@ func TestInMemory_E2E_DiscoverSuccess(t *testing.T) {
// TestInMemory_E2E_DiscoverFallback_NoOverlap verifies the fallback path
// over an InMemory (STDIO-equivalent) transport: the client probes with
// _meta.protocolVersion = 2026-07-28, but the server's supported list does
// NOT include that version (the default for an SDK server that hasn't
// shimmed supportedProtocolVersions).
// _meta.protocolVersion = 2026-07-28, but the server overrides discover via
// middleware to advertise only legacy versions, so the client must fall
// back to the legacy initialize handshake.
func TestInMemory_E2E_DiscoverFallback_NoOverlap(t *testing.T) {
ctx := context.Background()
orig := supportedProtocolVersions
supportedProtocolVersions = append([]string{protocolVersion20260728}, slices.Clone(orig)...)
t.Cleanup(func() { supportedProtocolVersions = orig })
server := NewServer(&Implementation{Name: "vpre-like-server", Version: "v1"}, nil)
// Intercept discover and reply as if we were a server that only
// supports legacy versions.
@ -932,9 +912,11 @@ func TestInMemory_E2E_DiscoverFallback_NoOverlap(t *testing.T) {
if ir == nil {
t.Fatal("InitializeResult is nil after fallback initialize")
}
if ir.ProtocolVersion != latestProtocolVersion {
// The fallback initialize explicitly requests protocolVersion20251125
// (see client.go), so the server negotiates that version.
if ir.ProtocolVersion != protocolVersion20251125 {
t.Errorf("InitializeResult.ProtocolVersion = %q, want %q (legacy fallback after no-overlap discover)",
ir.ProtocolVersion, latestProtocolVersion)
ir.ProtocolVersion, protocolVersion20251125)
}
// Prove the session is usable after fallback.
@ -949,10 +931,6 @@ func TestInMemory_E2E_DiscoverFallback_NoOverlap(t *testing.T) {
func TestInMemory_E2E_DiscoverFallback_MethodNotFound(t *testing.T) {
ctx := context.Background()
orig := supportedProtocolVersions
supportedProtocolVersions = append([]string{protocolVersion20260728}, slices.Clone(orig)...)
t.Cleanup(func() { supportedProtocolVersions = orig })
server := NewServer(&Implementation{Name: "vpre-server", Version: "v1"}, nil)
server.AddReceivingMiddleware(func(next MethodHandler) MethodHandler {
return func(ctx context.Context, method string, req Request) (Result, error) {
@ -981,9 +959,11 @@ func TestInMemory_E2E_DiscoverFallback_MethodNotFound(t *testing.T) {
if ir == nil {
t.Fatal("InitializeResult is nil after fallback initialize")
}
if ir.ProtocolVersion != latestProtocolVersion {
// The fallback initialize explicitly requests protocolVersion20251125
// (see client.go), so the server negotiates that version.
if ir.ProtocolVersion != protocolVersion20251125 {
t.Errorf("InitializeResult.ProtocolVersion = %q, want %q (legacy fallback after MethodNotFound)",
ir.ProtocolVersion, latestProtocolVersion)
ir.ProtocolVersion, protocolVersion20251125)
}
if _, err := cs.ListTools(ctx, nil); err != nil {
@ -998,10 +978,6 @@ func TestInMemory_E2E_DiscoverFallback_MethodNotFound(t *testing.T) {
func TestInMemory_E2E_DiscoverFallback_UnsupportedProtocolVersion(t *testing.T) {
ctx := context.Background()
orig := supportedProtocolVersions
supportedProtocolVersions = append([]string{protocolVersion20260728}, slices.Clone(orig)...)
t.Cleanup(func() { supportedProtocolVersions = orig })
server := NewServer(&Implementation{Name: "strict-server", Version: "v1"}, nil)
server.AddReceivingMiddleware(func(next MethodHandler) MethodHandler {
return func(ctx context.Context, method string, req Request) (Result, error) {
@ -1033,9 +1009,11 @@ func TestInMemory_E2E_DiscoverFallback_UnsupportedProtocolVersion(t *testing.T)
if ir == nil {
t.Fatal("InitializeResult is nil after fallback initialize")
}
if ir.ProtocolVersion != latestProtocolVersion {
// The fallback initialize explicitly requests protocolVersion20251125
// (see client.go), so the server negotiates that version.
if ir.ProtocolVersion != protocolVersion20251125 {
t.Errorf("InitializeResult.ProtocolVersion = %q, want %q (legacy fallback after UnsupportedProtocolVersion)",
ir.ProtocolVersion, latestProtocolVersion)
ir.ProtocolVersion, protocolVersion20251125)
}
}
@ -1045,10 +1023,6 @@ func TestInMemory_E2E_DiscoverFallback_UnsupportedProtocolVersion(t *testing.T)
// UnsupportedProtocolVersionError carries Data.Supported, and the client
// selects a mutually supported version from that list and retries.
func TestClientConnectDiscover_UnsupportedVersionNegotiation(t *testing.T) {
oldSupported := supportedProtocolVersions
supportedProtocolVersions = append([]string{protocolVersion20260728}, slices.Clone(oldSupported)...)
t.Cleanup(func() { supportedProtocolVersions = oldSupported })
ctx := context.Background()
const unsupportedClientVersion = "2099-12-31"