Add storage block geometry to audit and viewer

audit/internal/webui/server.go

@@ -572,6 +572,7 @@ func (h *handler) handleExportIndex(w http.ResponseWriter, r *http.Request) {
 
 func (h *handler) handleViewer(w http.ResponseWriter, r *http.Request) {
 	snapshot, _ := loadSnapshot(h.opts.AuditPath)
+	snapshot = enrichSnapshotForViewer(snapshot)
 	body, err := viewer.RenderHTML(snapshot, h.opts.Title)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)

audit/internal/webui/server_test.go

@@ -1016,6 +1016,39 @@ func TestViewerRendersLatestSnapshot(t *testing.T) {
 	}
 }
 
+func TestViewerRendersDerivedStorageBlockFormat(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "audit.json")
+	body := `{
+	  "collected_at":"2026-04-29T00:05:00Z",
+	  "hardware":{
+	    "board":{"serial_number":"SERIAL-NEW"},
+	    "storage":[
+	      {
+	        "serial_number":"DISK-1",
+	        "model":"Test NVMe",
+	        "logical_block_size_bytes":512,
+	        "physical_block_size_bytes":4096,
+	        "metadata_bytes_per_block":8
+	      }
+	    ]
+	  }
+	}`
+	if err := os.WriteFile(path, []byte(body), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	handler := NewHandler(HandlerOptions{AuditPath: path})
+	rec := httptest.NewRecorder()
+	handler.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/viewer", nil))
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status=%d", rec.Code)
+	}
+	if !strings.Contains(rec.Body.String(), "512+8") {
+		t.Fatalf("viewer body missing derived block format: %s", rec.Body.String())
+	}
+}
+
 func TestAuditJSONServesLatestSnapshot(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "audit.json")
@@ -1038,6 +1071,36 @@ func TestAuditJSONServesLatestSnapshot(t *testing.T) {
 	}
 }
 
+func TestAuditJSONDoesNotInjectDerivedStorageBlockFormat(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "audit.json")
+	body := `{
+	  "hardware":{
+	    "board":{"serial_number":"SERIAL-API"},
+	    "storage":[
+	      {
+	        "serial_number":"DISK-1",
+	        "logical_block_size_bytes":512,
+	        "metadata_bytes_per_block":8
+	      }
+	    ]
+	  }
+	}`
+	if err := os.WriteFile(path, []byte(body), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	handler := NewHandler(HandlerOptions{AuditPath: path})
+	rec := httptest.NewRecorder()
+	handler.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/audit.json", nil))
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status=%d", rec.Code)
+	}
+	if strings.Contains(rec.Body.String(), "block_format") {
+		t.Fatalf("audit.json should remain contract-only: %s", rec.Body.String())
+	}
+}
+
 func TestMissingAuditJSONReturnsNotFound(t *testing.T) {
 	handler := NewHandler(HandlerOptions{AuditPath: "/missing/audit.json"})
 	rec := httptest.NewRecorder()

audit/internal/webui/viewer_snapshot.go

@@ -0,0 +1,62 @@
+package webui
+
+import (
+	"encoding/json"
+	"strconv"
+)
+
+func enrichSnapshotForViewer(snapshot []byte) []byte {
+	if len(snapshot) == 0 {
+		return snapshot
+	}
+	var root map[string]any
+	if err := json.Unmarshal(snapshot, &root); err != nil {
+		return snapshot
+	}
+	hardware, _ := root["hardware"].(map[string]any)
+	if len(hardware) == 0 {
+		return snapshot
+	}
+	storage, _ := hardware["storage"].([]any)
+	if len(storage) == 0 {
+		return snapshot
+	}
+	changed := false
+	for _, item := range storage {
+		row, _ := item.(map[string]any)
+		if len(row) == 0 {
+			continue
+		}
+		if _, exists := row["block_format"]; exists {
+			continue
+		}
+		logical, okLogical := jsonNumberToInt64(row["logical_block_size_bytes"])
+		metadata, okMetadata := jsonNumberToInt64(row["metadata_bytes_per_block"])
+		if !okLogical || !okMetadata || logical <= 0 || metadata < 0 {
+			continue
+		}
+		row["block_format"] = strconv.FormatInt(logical, 10) + "+" + strconv.FormatInt(metadata, 10)
+		changed = true
+	}
+	if !changed {
+		return snapshot
+	}
+	out, err := json.Marshal(root)
+	if err != nil {
+		return snapshot
+	}
+	return out
+}
+
+func jsonNumberToInt64(v any) (int64, bool) {
+	switch x := v.(type) {
+	case float64:
+		return int64(x), true
+	case int64:
+		return x, true
+	case int:
+		return int64(x), true
+	default:
+		return 0, false
+	}
+}