fix(vibes): reject typed-nil capability implementations

Author: mgomes

vibes/capability_common.go

@@ -2,6 +2,7 @@ package vibes
 
 import (
 	"fmt"
+	"reflect"
 	"strings"
 )
 
@@ -33,3 +34,16 @@ func validateCapabilityKwargsDataOnly(method string, kwargs map[string]Value) er
 	}
 	return nil
 }
+
+func isNilCapabilityImplementation(impl any) bool {
+	if impl == nil {
+		return true
+	}
+	val := reflect.ValueOf(impl)
+	switch val.Kind() {
+	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Pointer, reflect.Slice:
+		return val.IsNil()
+	default:
+		return false
+	}
+}

vibes/capability_db.go

@@ -53,7 +53,7 @@ func NewDBCapability(name string, db Database) (CapabilityAdapter, error) {
 	if name == "" {
 		return nil, fmt.Errorf("vibes: database capability name must be non-empty")
 	}
-	if db == nil {
+	if isNilCapabilityImplementation(db) {
 		return nil, fmt.Errorf("vibes: database capability requires a non-nil implementation")
 	}
 	return &dbCapability{name: name, db: db}, nil

vibes/capability_db_test.go

@@ -280,4 +280,9 @@ func TestNewDBCapabilityRejectsInvalidArguments(t *testing.T) {
 	if _, err := NewDBCapability("db", db); err == nil || !strings.Contains(err.Error(), "requires a non-nil implementation") {
 		t.Fatalf("expected nil db error, got %v", err)
 	}
+
+	var typedNil *dbCapabilityStub
+	if _, err := NewDBCapability("db", typedNil); err == nil || !strings.Contains(err.Error(), "requires a non-nil implementation") {
+		t.Fatalf("expected typed nil db error, got %v", err)
+	}
 }

vibes/capability_events.go

@@ -22,7 +22,7 @@ func NewEventsCapability(name string, publisher EventPublisher) (CapabilityAdapt
 	if name == "" {
 		return nil, fmt.Errorf("vibes: events capability name must be non-empty")
 	}
-	if publisher == nil {
+	if isNilCapabilityImplementation(publisher) {
 		return nil, fmt.Errorf("vibes: events capability requires a non-nil implementation")
 	}
 	return &eventsCapability{name: name, publisher: publisher}, nil

vibes/capability_events_test.go

@@ -123,4 +123,9 @@ func TestNewEventsCapabilityRejectsInvalidArguments(t *testing.T) {
 	if _, err := NewEventsCapability("events", publisher); err == nil || !strings.Contains(err.Error(), "requires a non-nil implementation") {
 		t.Fatalf("expected nil publisher error, got %v", err)
 	}
+
+	var typedNil *eventsCapabilityStub
+	if _, err := NewEventsCapability("events", typedNil); err == nil || !strings.Contains(err.Error(), "requires a non-nil implementation") {
+		t.Fatalf("expected typed nil publisher error, got %v", err)
+	}
 }

vibes/capability_jobqueue.go

@@ -43,7 +43,7 @@ func NewJobQueueCapability(name string, queue JobQueue) (CapabilityAdapter, erro
 	if name == "" {
 		return nil, fmt.Errorf("vibes: job queue capability name must be non-empty")
 	}
-	if queue == nil {
+	if isNilCapabilityImplementation(queue) {
 		return nil, fmt.Errorf("vibes: job queue capability requires a non-nil implementation")
 	}
 

vibes/capability_jobqueue_test.go

@@ -328,4 +328,13 @@ func TestNewJobQueueCapabilityRejectsNilQueue(t *testing.T) {
 	if got := err.Error(); !strings.Contains(got, "requires a non-nil implementation") {
 		t.Fatalf("unexpected error: %s", got)
 	}
+
+	var typedNil *jobQueueStub
+	_, err = NewJobQueueCapability("jobs", typedNil)
+	if err == nil {
+		t.Fatalf("expected typed nil queue to fail")
+	}
+	if got := err.Error(); !strings.Contains(got, "requires a non-nil implementation") {
+		t.Fatalf("unexpected typed nil error: %s", got)
+	}
 }