fix(ruletypes): mark threshold variant kind/spec required

Revert the json:"-" + custom MarshalJSON dance on the envelope
structs. Restore the original tags (json:"kind" / json:"spec"),
keep the discriminator marker, and clear the parent's redundant
properties / required block in attachDiscriminators after the
discriminator is promoted.

docs/api/openapi.yml

@@ -4348,19 +4348,20 @@ components:
           $ref: '#/components/schemas/RuletypesEvaluationKind'
         spec:
           $ref: '#/components/schemas/RuletypesCumulativeWindow'
-      type: object
-    RuletypesEvaluationEnvelope:
-      oneOf:
-      - $ref: '#/components/schemas/RuletypesEvaluationRolling'
-      - $ref: '#/components/schemas/RuletypesEvaluationCumulative'
-      properties:
-        kind:
-          $ref: '#/components/schemas/RuletypesEvaluationKind'
-        spec: {}
       required:
       - kind
       - spec
       type: object
+    RuletypesEvaluationEnvelope:
+      discriminator:
+        mapping:
+          cumulative: '#/components/schemas/RuletypesEvaluationCumulative'
+          rolling: '#/components/schemas/RuletypesEvaluationRolling'
+        propertyName: kind
+      oneOf:
+      - $ref: '#/components/schemas/RuletypesEvaluationRolling'
+      - $ref: '#/components/schemas/RuletypesEvaluationCumulative'
+      type: object
     RuletypesEvaluationKind:
       enum:
       - rolling
@@ -4372,6 +4373,9 @@ components:
           $ref: '#/components/schemas/RuletypesEvaluationKind'
         spec:
           $ref: '#/components/schemas/RuletypesRollingWindow'
+      required:
+      - kind
+      - spec
       type: object
     RuletypesGettableTestRule:
       properties:
@@ -4679,15 +4683,12 @@ components:
       - compositeQuery
       type: object
     RuletypesRuleThresholdData:
+      discriminator:
+        mapping:
+          basic: '#/components/schemas/RuletypesThresholdBasic'
+        propertyName: kind
       oneOf:
       - $ref: '#/components/schemas/RuletypesThresholdBasic'
-      properties:
-        kind:
-          $ref: '#/components/schemas/RuletypesThresholdKind'
-        spec: {}
-      required:
-      - kind
-      - spec
       type: object
     RuletypesRuleType:
       enum:
@@ -4729,6 +4730,9 @@ components:
           $ref: '#/components/schemas/RuletypesThresholdKind'
         spec:
           $ref: '#/components/schemas/RuletypesBasicRuleThresholds'
+      required:
+      - kind
+      - spec
       type: object
     RuletypesThresholdKind:
       enum:

frontend/src/api/generated/services/sigNoz.schemas.ts

@@ -6578,28 +6578,36 @@ export interface RuletypesCumulativeWindowDTO {
 	timezone: string;
 }
 
+export enum RuletypesEvaluationCumulativeDTOKind {
+	cumulative = 'cumulative',
+}
 export interface RuletypesEvaluationCumulativeDTO {
-	kind?: RuletypesEvaluationKindDTO;
-	spec?: RuletypesCumulativeWindowDTO;
+	/**
+	 * @type string
+	 * @enum cumulative
+	 */
+	kind: RuletypesEvaluationCumulativeDTOKind;
+	spec: RuletypesCumulativeWindowDTO;
 }
 
 export type RuletypesEvaluationEnvelopeDTO =
-	| (RuletypesEvaluationRollingDTO & {
-			kind: RuletypesEvaluationKindDTO;
-			spec: unknown;
-	  })
-	| (RuletypesEvaluationCumulativeDTO & {
-			kind: RuletypesEvaluationKindDTO;
-			spec: unknown;
-	  });
+	| RuletypesEvaluationRollingDTO
+	| RuletypesEvaluationCumulativeDTO;
 
 export enum RuletypesEvaluationKindDTO {
 	rolling = 'rolling',
 	cumulative = 'cumulative',
 }
+export enum RuletypesEvaluationRollingDTOKind {
+	rolling = 'rolling',
+}
 export interface RuletypesEvaluationRollingDTO {
-	kind?: RuletypesEvaluationKindDTO;
-	spec?: RuletypesRollingWindowDTO;
+	/**
+	 * @type string
+	 * @enum rolling
+	 */
+	kind: RuletypesEvaluationRollingDTOKind;
+	spec: RuletypesRollingWindowDTO;
 }
 
 export interface RuletypesGettableTestRuleDTO {
@@ -6954,10 +6962,7 @@ export interface RuletypesRuleConditionDTO {
 	thresholds?: RuletypesRuleThresholdDataDTO;
 }
 
-export type RuletypesRuleThresholdDataDTO = RuletypesThresholdBasicDTO & {
-	kind: RuletypesThresholdKindDTO;
-	spec: unknown;
-};
+export type RuletypesRuleThresholdDataDTO = RuletypesThresholdBasicDTO;
 
 export enum RuletypesRuleTypeDTO {
 	threshold_rule = 'threshold_rule',
@@ -6993,9 +6998,16 @@ export enum RuletypesSeasonalityDTO {
 	daily = 'daily',
 	weekly = 'weekly',
 }
+export enum RuletypesThresholdBasicDTOKind {
+	basic = 'basic',
+}
 export interface RuletypesThresholdBasicDTO {
-	kind?: RuletypesThresholdKindDTO;
-	spec?: RuletypesBasicRuleThresholdsDTO;
+	/**
+	 * @type string
+	 * @enum basic
+	 */
+	kind: RuletypesThresholdBasicDTOKind;
+	spec: RuletypesBasicRuleThresholdsDTO;
 }
 
 export enum RuletypesThresholdKindDTO {

pkg/signoz/openapi.go

@@ -44,6 +44,8 @@ import (
 	"gopkg.in/yaml.v2"
 )
 
+const signozDiscriminatorKey string = "x-signoz-discriminator"
+
 type OpenAPI struct {
 	apiserver apiserver.APIServer
 	reflector *openapi3.Reflector
@@ -142,6 +144,8 @@ func (openapi *OpenAPI) CreateAndWrite(path string) error {
 		return err
 	}
 
+	attachDiscriminators(openapi.reflector.Spec)
+
 	// The library's MarshalYAML does a JSON round-trip that converts all numbers
 	// to float64, causing large integers (e.g. epoch millisecond timestamps) to
 	// render in scientific notation (1.6409952e+12).
@@ -199,3 +203,59 @@ func convertJSONNumbers(v interface{}) {
 		}
 	}
 }
+
+// attachDiscriminators promotes x-signoz-discriminator extensions
+// into openapi3 Discriminator fields. Malformed markers are dropped.
+func attachDiscriminators(spec *openapi3.Spec) {
+	if spec.Components == nil || spec.Components.Schemas == nil {
+		return
+	}
+
+	for name, entry := range spec.Components.Schemas.MapOfSchemaOrRefValues {
+		if entry.Schema == nil {
+			continue
+		}
+
+		raw, ok := entry.Schema.MapOfAnything[signozDiscriminatorKey]
+		if !ok {
+			continue
+		}
+
+		marker, ok := raw.(map[string]any)
+		if !ok {
+			continue
+		}
+
+		propertyName, ok := marker["propertyName"].(string)
+		if !ok || propertyName == "" {
+			continue
+		}
+
+		disc := openapi3.Discriminator{PropertyName: propertyName}
+		if rawMapping, ok := marker["mapping"]; ok {
+			if mapping, ok := rawMapping.(map[string]string); ok {
+				disc.Mapping = mapping
+			} else if mapping, ok := rawMapping.(map[string]any); ok {
+				converted := make(map[string]string, len(mapping))
+				for k, v := range mapping {
+					if s, ok := v.(string); ok {
+						converted[k] = s
+					}
+				}
+				disc.Mapping = converted
+			}
+		}
+
+		entry.Schema.Discriminator = &disc
+		delete(entry.Schema.MapOfAnything, signozDiscriminatorKey)
+
+		// The parent's reflected `properties` / `required` duplicate
+		// what the oneOf variants already declare, and orval intersects
+		// the two — turning a clean discriminated union DTO into a
+		// noisy union of intersections. Drop them here.
+		entry.Schema.Properties = nil
+		entry.Schema.Required = nil
+
+		spec.Components.Schemas.MapOfSchemaOrRefValues[name] = entry
+	}
+}

pkg/types/ruletypes/evaluation.go

@@ -250,17 +250,20 @@ type EvaluationEnvelope struct {
 
 // evaluationRolling is the OpenAPI schema for an EvaluationEnvelope with kind=rolling.
 type evaluationRolling struct {
-	Kind EvaluationKind `json:"kind" description:"The kind of evaluation."`
-	Spec RollingWindow  `json:"spec" description:"The rolling window evaluation specification."`
+	Kind EvaluationKind `json:"kind" description:"The kind of evaluation." required:"true"`
+	Spec RollingWindow  `json:"spec" description:"The rolling window evaluation specification." required:"true"`
 }
 
 // evaluationCumulative is the OpenAPI schema for an EvaluationEnvelope with kind=cumulative.
 type evaluationCumulative struct {
-	Kind EvaluationKind   `json:"kind" description:"The kind of evaluation."`
-	Spec CumulativeWindow `json:"spec" description:"The cumulative window evaluation specification."`
+	Kind EvaluationKind   `json:"kind" description:"The kind of evaluation." required:"true"`
+	Spec CumulativeWindow `json:"spec" description:"The cumulative window evaluation specification." required:"true"`
 }
 
-var _ jsonschema.OneOfExposer = EvaluationEnvelope{}
+var (
+	_ jsonschema.OneOfExposer = EvaluationEnvelope{}
+	_ jsonschema.Preparer     = EvaluationEnvelope{}
+)
 
 // JSONSchemaOneOf returns the oneOf variants for the EvaluationEnvelope discriminated union.
 // Each variant represents a different evaluation kind with its corresponding spec schema.
@@ -271,6 +274,22 @@ func (EvaluationEnvelope) JSONSchemaOneOf() []any {
 	}
 }
 
+func (EvaluationEnvelope) PrepareJSONSchema(schema *jsonschema.Schema) error {
+	if schema.ExtraProperties == nil {
+		schema.ExtraProperties = map[string]any{}
+	}
+
+	schema.ExtraProperties["x-signoz-discriminator"] = map[string]any{
+		"propertyName": "kind",
+		"mapping": map[string]string{
+			"rolling":    "#/components/schemas/RuletypesEvaluationRolling",
+			"cumulative": "#/components/schemas/RuletypesEvaluationCumulative",
+		},
+	}
+
+	return nil
+}
+
 func (e *EvaluationEnvelope) UnmarshalJSON(data []byte) error {
 	var raw map[string]json.RawMessage
 	if err := json.Unmarshal(data, &raw); err != nil {

pkg/types/ruletypes/threshold.go

@@ -36,11 +36,14 @@ type RuleThresholdData struct {
 
 // thresholdBasic is the OpenAPI schema for a RuleThresholdData with kind=basic.
 type thresholdBasic struct {
-	Kind ThresholdKind       `json:"kind" description:"The kind of threshold."`
-	Spec BasicRuleThresholds `json:"spec" description:"The basic threshold specification (array of thresholds)."`
+	Kind ThresholdKind       `json:"kind" description:"The kind of threshold." required:"true"`
+	Spec BasicRuleThresholds `json:"spec" description:"The basic threshold specification (array of thresholds)." required:"true"`
 }
 
-var _ jsonschema.OneOfExposer = RuleThresholdData{}
+var (
+	_ jsonschema.OneOfExposer = RuleThresholdData{}
+	_ jsonschema.Preparer     = RuleThresholdData{}
+)
 
 // JSONSchemaOneOf returns the oneOf variants for the RuleThresholdData discriminated union.
 // Each variant represents a different threshold kind with its corresponding spec schema.
@@ -50,6 +53,24 @@ func (RuleThresholdData) JSONSchemaOneOf() []any {
 	}
 }
 
+// PrepareJSONSchema marks the schema with x-signoz-discriminator;
+// signoz.attachDiscriminators promotes it to a real OpenAPI 3
+// discriminator after reflection.
+func (RuleThresholdData) PrepareJSONSchema(schema *jsonschema.Schema) error {
+	if schema.ExtraProperties == nil {
+		schema.ExtraProperties = map[string]any{}
+	}
+
+	schema.ExtraProperties["x-signoz-discriminator"] = map[string]any{
+		"propertyName": "kind",
+		"mapping": map[string]string{
+			"basic": "#/components/schemas/RuletypesThresholdBasic",
+		},
+	}
+
+	return nil
+}
+
 func (r *RuleThresholdData) UnmarshalJSON(data []byte) error {
 	var raw map[string]json.RawMessage
 	if err := json.Unmarshal(data, &raw); err != nil {