fix(diagnostics): classify auto-detected stdio servers (resolved transport hint)

Codex review round on PR #606: the supervisor built the classifier transport
hint from raw Config.Protocol, so auto-detected stdio servers (Protocol=='' +
Command!='') missed the stdio-gated rules and stayed UNKNOWN. Use
transport.DetermineTransportType(config) at both hint sites so the resolved
transport drives classification + add a DetermineTransportType regression test.

Related #599

Author: Dumbris

internal/runtime/supervisor/supervisor.go

@@ -15,6 +15,7 @@ import (
 	"github.com/smart-mcp-proxy/mcpproxy-go/internal/diagnostics"
 	"github.com/smart-mcp-proxy/mcpproxy-go/internal/runtime/configsvc"
 	"github.com/smart-mcp-proxy/mcpproxy-go/internal/runtime/stateview"
+	transportpkg "github.com/smart-mcp-proxy/mcpproxy-go/internal/transport"
 	"github.com/smart-mcp-proxy/mcpproxy-go/internal/upstream/types"
 )
 
@@ -696,9 +697,12 @@ func (s *Supervisor) updateStateView(name string, state *ServerState) {
 				status.LastError = errorStr
 
 				// Spec 044: classify raw error into stable diagnostic code.
+				// Use the RESOLVED transport, not the raw Config.Protocol: an
+				// auto-detected stdio server has Protocol=="" + Command!="" and
+				// would otherwise miss the stdio-gated classifier rules (#599).
 				transport := ""
 				if state.Config != nil {
-					transport = string(state.Config.Protocol)
+					transport = transportpkg.DetermineTransportType(state.Config)
 				}
 				classifyAndAttach(status, state.ConnectionInfo.LastError, transport)
 				// Spec 044 Phase H: notify telemetry counter store.
@@ -969,9 +973,12 @@ func (s *Supervisor) updateSnapshotFromEvent(event Event) {
 						status.LastError = errorStr
 
 						// Spec 044: classify raw error into stable diagnostic code.
+						// Resolved transport (not raw Config.Protocol) so auto-detected
+						// stdio servers (Protocol=="" + Command!="") hit the stdio
+						// classifier rules (#599).
 						transport := ""
 						if status.Config != nil {
-							transport = string(status.Config.Protocol)
+							transport = transportpkg.DetermineTransportType(status.Config)
 						}
 						classifyAndAttach(status, connInfo.LastError, transport)
 						// Spec 044 Phase H: notify telemetry counter store.

internal/transport/transport_type_test.go

@@ -0,0 +1,33 @@
+package transport
+
+import (
+	"testing"
+
+	"github.com/smart-mcp-proxy/mcpproxy-go/internal/config"
+)
+
+// Locks the behavior the supervisor classifier hint relies on (#599 / PR #606):
+// an auto-detected stdio server (empty/auto protocol + a command) must resolve to
+// stdio, so the stdio-gated diagnostic rules fire for it — using the raw
+// Config.Protocol would leave such servers unclassified.
+func TestDetermineTransportType(t *testing.T) {
+	cases := []struct {
+		name string
+		cfg  config.ServerConfig
+		want string
+	}{
+		{"explicit stdio", config.ServerConfig{Protocol: "stdio"}, TransportStdio},
+		{"auto-detected stdio (empty protocol + command)", config.ServerConfig{Command: "npx"}, TransportStdio},
+		{"auto protocol + command", config.ServerConfig{Protocol: "auto", Command: "docker"}, TransportStdio},
+		{"empty protocol + url", config.ServerConfig{URL: "https://example.com/mcp"}, TransportStreamableHTTP},
+		{"explicit http", config.ServerConfig{Protocol: "http", URL: "https://example.com/mcp"}, "http"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			cfg := tc.cfg
+			if got := DetermineTransportType(&cfg); got != tc.want {
+				t.Errorf("DetermineTransportType(%+v) = %q, want %q", tc.cfg, got, tc.want)
+			}
+		})
+	}
+}