Go SDK: Align hooks with SEP

go/sdk/README.md

@@ -20,10 +20,10 @@ ext := extension.New()
 ext.AddInterceptor(&interceptors.Validator{
     Metadata: interceptors.Metadata{
         Name: "block-dangerous",
-        Hook: interceptors.Hook{
+        Hooks: []interceptors.Hook{{
             Events: []string{interceptors.EventToolsCall},
             Phase:  interceptors.PhaseRequest,
-        },
+        }},
         Mode: interceptors.ModeEnforce,
     },
     Handler: func(_ context.Context, inv *interceptors.Invocation) (*interceptors.ValidationResult, error) {

go/sdk/examples/mutator/main.go

@@ -37,10 +37,10 @@ func main() {
 	m := &interceptors.Mutator{
 		Metadata: interceptors.Metadata{
 			Name: "audit-tag",
-			Hook: interceptors.Hook{
+			Hooks: []interceptors.Hook{{
 				Events: []string{interceptors.EventToolsCall},
 				Phase:  interceptors.PhaseResponse,
-			},
+			}},
 			Mode: interceptors.ModeEnforce,
 		},
 		Handler: func(_ context.Context, inv *interceptors.Invocation) (*interceptors.MutationResult, error) {

go/sdk/examples/validator/main.go

@@ -37,10 +37,10 @@ func main() {
 	v := &interceptors.Validator{
 		Metadata: interceptors.Metadata{
 			Name: "block-dangerous-tool",
-			Hook: interceptors.Hook{
+			Hooks: []interceptors.Hook{{
 				Events: []string{interceptors.EventToolsCall},
 				Phase:  interceptors.PhaseRequest,
-			},
+			}},
 			Mode: interceptors.ModeEnforce,
 		},
 		Handler: func(_ context.Context, inv *interceptors.Invocation) (*interceptors.ValidationResult, error) {

go/sdk/interceptors/chain/chain.go

@@ -143,10 +143,7 @@ func (c *Chain) Execute(ctx context.Context, params *ExecutionParams) (*Executio
 		if len(nameFilter) > 0 && !nameFilter[e.Interceptor.Name] {
 			continue
 		}
-		if !matchesPhase(e.Interceptor.Hook.Phase, params.Phase) {
-			continue
-		}
-		if !slices.Contains(e.Interceptor.Hook.Events, params.Event) {
+		if !matchesHooks(e.Interceptor.Hooks, params.Event, params.Phase) {
 			continue
 		}
 		switch e.Interceptor.Type {
@@ -432,8 +429,16 @@ func (c *Chain) timeoutResult(cr *ExecutionResult, start time.Time) {
 	})
 }
 
-// matchesPhase checks if an interceptor's configured phase covers the target
-// phase. An interceptor with PhaseBoth matches any target phase.
-func matchesPhase(interceptorPhase, targetPhase interceptors.InterceptionPhase) bool {
-	return interceptorPhase == interceptors.PhaseBoth || interceptorPhase == targetPhase
+// matchesHooks checks if any hook entry matches both the target event and phase.
+// A hook with PhaseBoth matches any target phase.
+func matchesHooks(hooks []interceptors.Hook, event string, phase interceptors.InterceptionPhase) bool {
+	for _, h := range hooks {
+		if h.Phase != interceptors.PhaseBoth && h.Phase != phase {
+			continue
+		}
+		if slices.Contains(h.Events, event) {
+			return true
+		}
+	}
+	return false
 }

go/sdk/interceptors/chain/chain_test.go

@@ -67,10 +67,12 @@ func registerInterceptorMethods(server *mcp.Server, is []interceptors.Intercepto
 			for _, i := range is {
 				if event != "" {
 					match := false
-					for _, e := range i.GetMetadata().Hook.Events {
-						if e == event {
-							match = true
-							break
+					for _, h := range i.GetMetadata().Hooks {
+						for _, e := range h.Events {
+							if e == event {
+								match = true
+								break
+							}
 						}
 					}
 					if !match {
@@ -142,10 +144,10 @@ func TestChain_FailOpenRecordsExecutionResult(t *testing.T) {
 		failOpenValidator := &interceptors.Validator{
 			Metadata: interceptors.Metadata{
 				Name: "fo-validator",
-				Hook: interceptors.Hook{
+				Hooks: []interceptors.Hook{{
 					Events: []string{"test/event"},
 					Phase:  interceptors.PhaseRequest,
-				},
+				}},
 				Mode:     interceptors.ModeEnforce,
 				FailOpen: true,
 			},
@@ -156,10 +158,10 @@ func TestChain_FailOpenRecordsExecutionResult(t *testing.T) {
 		passingValidator := &interceptors.Validator{
 			Metadata: interceptors.Metadata{
 				Name: "passing-validator",
-				Hook: interceptors.Hook{
+				Hooks: []interceptors.Hook{{
 					Events: []string{"test/event"},
 					Phase:  interceptors.PhaseRequest,
-				},
+				}},
 				Mode: interceptors.ModeEnforce,
 			},
 			Handler: func(_ context.Context, _ *interceptors.Invocation) (*interceptors.ValidationResult, error) {
@@ -190,10 +192,10 @@ func TestChain_FailOpenRecordsExecutionResult(t *testing.T) {
 		failOpenMutator := &interceptors.Mutator{
 			Metadata: interceptors.Metadata{
 				Name: "fo-mutator",
-				Hook: interceptors.Hook{
+				Hooks: []interceptors.Hook{{
 					Events: []string{"test/event"},
 					Phase:  interceptors.PhaseResponse,
-				},
+				}},
 				Mode:         interceptors.ModeEnforce,
 				FailOpen:     true,
 				PriorityHint: interceptors.NewPriority(10),
@@ -205,10 +207,10 @@ func TestChain_FailOpenRecordsExecutionResult(t *testing.T) {
 		passingMutator := &interceptors.Mutator{
 			Metadata: interceptors.Metadata{
 				Name: "passing-mutator",
-				Hook: interceptors.Hook{
+				Hooks: []interceptors.Hook{{
 					Events: []string{"test/event"},
 					Phase:  interceptors.PhaseResponse,
-				},
+				}},
 				Mode:         interceptors.ModeEnforce,
 				PriorityHint: interceptors.NewPriority(20),
 			},

go/sdk/interceptors/doc.go

@@ -45,10 +45,10 @@
 //	v := &interceptors.Validator{
 //	    Metadata: interceptors.Metadata{
 //	        Name: "block-dangerous-tool",
-//	        Hook: interceptors.Hook{
+//	        Hooks: []interceptors.Hook{{
 //	            Events: []string{"tools/call"},
 //	            Phase:  interceptors.PhaseRequest,
-//	        },
+//	        }},
 //	        Mode: interceptors.ModeEnforce,
 //	    },
 //	    Handler: func(ctx context.Context, inv *interceptors.Invocation) (*interceptors.ValidationResult, error) {
@@ -73,10 +73,10 @@
 //	m := &interceptors.Mutator{
 //	    Metadata: interceptors.Metadata{
 //	        Name: "redact-pii",
-//	        Hook: interceptors.Hook{
+//	        Hooks: []interceptors.Hook{{
 //	            Events: []string{"tools/call"},
 //	            Phase:  interceptors.PhaseResponse,
-//	        },
+//	        }},
 //	        Mode: interceptors.ModeEnforce,
 //	    },
 //	    Handler: func(ctx context.Context, inv *interceptors.Invocation) (*interceptors.MutationResult, error) {

go/sdk/interceptors/extension/rpc.go

@@ -27,7 +27,7 @@ func (e *Extension) handleList(_ context.Context, req *mcp.ServerRequest[*interc
 	all := e.getInterceptors()
 	infos := make([]interceptors.InterceptorInfo, 0, len(all))
 	for _, ri := range all {
-		if event != "" && !slices.Contains(ri.GetMetadata().Hook.Events, event) {
+		if event != "" && !hooksContainEvent(ri.GetMetadata().Hooks, event) {
 			continue
 		}
 		infos = append(infos, interceptors.InfoFromInterceptor(ri))
@@ -105,3 +105,12 @@ func (e *Extension) handleInvoke(ctx context.Context, req *mcp.ServerRequest[*in
 
 	return result, nil
 }
+
+func hooksContainEvent(hooks []interceptors.Hook, event string) bool {
+	for _, h := range hooks {
+		if slices.Contains(h.Events, event) {
+			return true
+		}
+	}
+	return false
+}

go/sdk/interceptors/extension/rpc_test.go

@@ -42,10 +42,10 @@ func TestListWithEventFilter(t *testing.T) {
 	promptsValidator := &interceptors.Validator{
 		Metadata: interceptors.Metadata{
 			Name: "prompts-v",
-			Hook: interceptors.Hook{
+			Hooks: []interceptors.Hook{{
 				Events: []string{interceptors.EventPromptsGet},
 				Phase:  interceptors.PhaseRequest,
-			},
+			}},
 			Mode: interceptors.ModeEnforce,
 		},
 		Handler: func(_ context.Context, _ *interceptors.Invocation) (*interceptors.ValidationResult, error) {
@@ -112,10 +112,10 @@ func TestInvokeValidatorRejects(t *testing.T) {
 	rejectAll := &interceptors.Validator{
 		Metadata: interceptors.Metadata{
 			Name: "reject-all",
-			Hook: interceptors.Hook{
+			Hooks: []interceptors.Hook{{
 				Events: []string{interceptors.EventToolsCall},
 				Phase:  interceptors.PhaseRequest,
-			},
+			}},
 			Mode: interceptors.ModeEnforce,
 		},
 		Handler: func(_ context.Context, _ *interceptors.Invocation) (*interceptors.ValidationResult, error) {
@@ -155,10 +155,10 @@ func TestInvokeMutator(t *testing.T) {
 	mutator := &interceptors.Mutator{
 		Metadata: interceptors.Metadata{
 			Name: "add-field",
-			Hook: interceptors.Hook{
+			Hooks: []interceptors.Hook{{
 				Events: []string{interceptors.EventToolsCall},
 				Phase:  interceptors.PhaseRequest,
-			},
+			}},
 			Mode: interceptors.ModeEnforce,
 		},
 		Handler: func(_ context.Context, inv *interceptors.Invocation) (*interceptors.MutationResult, error) {
@@ -231,10 +231,10 @@ func TestInvokeTimeout(t *testing.T) {
 	slowValidator := &interceptors.Validator{
 		Metadata: interceptors.Metadata{
 			Name: "slow-v",
-			Hook: interceptors.Hook{
+			Hooks: []interceptors.Hook{{
 				Events: []string{interceptors.EventToolsCall},
 				Phase:  interceptors.PhaseRequest,
-			},
+			}},
 			Mode: interceptors.ModeEnforce,
 		},
 		Handler: func(ctx context.Context, _ *interceptors.Invocation) (*interceptors.ValidationResult, error) {

go/sdk/interceptors/extension/server.go

@@ -181,8 +181,10 @@ func (e *Extension) enrichInitResult(result mcp.Result) (mcp.Result, error) {
 	all := e.getInterceptors()
 	supportedEvents := map[string]bool{}
 	for _, ri := range all {
-		for _, ev := range ri.GetMetadata().Hook.Events {
-			supportedEvents[ev] = true
+		for _, h := range ri.GetMetadata().Hooks {
+			for _, ev := range h.Events {
+				supportedEvents[ev] = true
+			}
 		}
 	}