feat: add InspectAttention pass-through on InferenceAdapter

Co-Authored-By: Virgil <virgil@lethean.io>

adapter.go

@@ -4,6 +4,7 @@ package ml
 
 import (
 	"context"
+	"fmt"
 	"strings"
 
 	"forge.lthn.ai/core/go-inference"
@@ -97,6 +98,17 @@ func (a *InferenceAdapter) Close() error { return a.model.Close() }
 // to Classify, BatchGenerate, Metrics, Info, etc.
 func (a *InferenceAdapter) Model() inference.TextModel { return a.model }
 
+// InspectAttention delegates to the underlying TextModel if it implements
+// inference.AttentionInspector. Returns an error if the backend does not support
+// attention inspection.
+func (a *InferenceAdapter) InspectAttention(ctx context.Context, prompt string, opts ...inference.GenerateOption) (*inference.AttentionSnapshot, error) {
+	inspector, ok := a.model.(inference.AttentionInspector)
+	if !ok {
+		return nil, fmt.Errorf("backend %q does not support attention inspection", a.name)
+	}
+	return inspector.InspectAttention(ctx, prompt, opts...)
+}
+
 // convertOpts maps ml.GenOpts to go-inference functional options.
 func convertOpts(opts GenOpts) []inference.GenerateOption {
 	var out []inference.GenerateOption

adapter_attention_test.go

@@ -0,0 +1,47 @@
+// SPDX-Licence-Identifier: EUPL-1.2
+
+package ml
+
+import (
+	"context"
+	"testing"
+
+	"forge.lthn.ai/core/go-inference"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// mockAttentionModel extends mockTextModel with AttentionInspector support.
+type mockAttentionModel struct {
+	mockTextModel
+}
+
+func (m *mockAttentionModel) InspectAttention(_ context.Context, _ string, _ ...inference.GenerateOption) (*inference.AttentionSnapshot, error) {
+	return &inference.AttentionSnapshot{
+		NumLayers:    28,
+		NumHeads:     8,
+		SeqLen:       10,
+		HeadDim:      64,
+		Architecture: "qwen3",
+	}, nil
+}
+
+func TestInferenceAdapter_InspectAttention_Good(t *testing.T) {
+	adapter := NewInferenceAdapter(&mockAttentionModel{}, "test")
+	snap, err := adapter.InspectAttention(context.Background(), "hello")
+	require.NoError(t, err)
+	assert.Equal(t, 28, snap.NumLayers)
+	assert.Equal(t, 8, snap.NumHeads)
+	assert.Equal(t, 10, snap.SeqLen)
+	assert.Equal(t, 64, snap.HeadDim)
+	assert.Equal(t, "qwen3", snap.Architecture)
+}
+
+func TestInferenceAdapter_InspectAttention_Unsupported_Bad(t *testing.T) {
+	// Plain mockTextModel does not implement AttentionInspector.
+	adapter := NewInferenceAdapter(&mockTextModel{}, "test")
+	_, err := adapter.InspectAttention(context.Background(), "hello")
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "does not support attention inspection")
+}