fix(mcp): harden dashboard dispatch lifecycle

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

cmd/dashboard/controller/mcp_result_encoding_test.go

@@ -0,0 +1,47 @@
+package controller
+
+import (
+	"encoding/json"
+	"strings"
+	"sync"
+	"testing"
+
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/require"
+
+	"github.com/nezhahq/nezha/model"
+)
+
+var registerUnmarshalableMCPTool sync.Once
+
+func TestMCPToolCall_unmarshalableSuccessResultReturnsExplicitToolError(t *testing.T) {
+	// Given
+	cleanup, uid := setupMCPTest(t)
+	defer cleanup()
+	registerUnmarshalableMCPTool.Do(func() {
+		registerMCPTool(&mcpTool{
+			Name:          "test.unmarshalable-success",
+			RequiredScope: "",
+			Handler: func(*gin.Context, json.RawMessage) (any, error) {
+				return map[string]any{"unsupported": func() {}}, nil
+			},
+		})
+	})
+	tok, plainToken := mkToken(t, uid, []string{model.ScopeServerRead}, nil)
+	require.NotEmpty(t, plainToken)
+	c, w := mcpCallCtx(t, tok, uid, jsonRPCRequest{
+		JSONRPC: "2.0", ID: json.RawMessage("1"), Method: "tools/call",
+		Params: jsonObj(t, toolCallParams{Name: "test.unmarshalable-success", Arguments: json.RawMessage("{}")}),
+	})
+
+	// When
+	mcpEndpoint(c)
+
+	// Then
+	_, result := decodeRPC(w)
+	require.NotNil(t, result)
+	require.True(t, result.IsError)
+	require.Nil(t, result.StructuredContent)
+	require.Len(t, result.Content, 1)
+	require.True(t, strings.Contains(result.Content[0].Text, "encode"), result.Content[0].Text)
+}