refactor: replace any with concrete types where shapes are known (check-safety 2e)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

block.go

@@ -2,38 +2,41 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"html"
 	"strings"
 )
 
+type smartBlockGeneration struct {
+	ID       string `json:"id"`
+	Template string `json:"template"`
+}
+
+type smartBlockMeta struct {
+	Generations         []smartBlockGeneration `json:"generations"`
+	CurrentGenerationID string                 `json:"currentGenerationId"`
+}
+
 // SmartBlockFunc renders a Smart Block by substituting {{field}} placeholders with content values.
 func SmartBlockFunc(ctx context.Context, content map[string]any) string {
-	// Get metadata
-	meta, ok := content["_meta"].(map[string]any)
-	if !ok {
+	rawMeta, err := json.Marshal(content["_meta"])
+	if err != nil {
+		return renderEmptyState()
+	}
+	var meta smartBlockMeta
+	if err := json.Unmarshal(rawMeta, &meta); err != nil {
 		return renderEmptyState()
 	}
 
-	generations, ok := meta["generations"].([]any)
-	if !ok || len(generations) == 0 {
+	if len(meta.Generations) == 0 || meta.CurrentGenerationID == "" {
 		return renderEmptyState()
 	}
 
-	currentID, _ := meta["currentGenerationId"].(string)
-	if currentID == "" {
-		return renderEmptyState()
-	}
-
-	// Find the current generation
 	var template string
-	for _, gen := range generations {
-		genMap, ok := gen.(map[string]any)
-		if !ok {
-			continue
-		}
-		if genMap["id"] == currentID {
-			template, _ = genMap["template"].(string)
+	for _, gen := range meta.Generations {
+		if gen.ID == meta.CurrentGenerationID {
+			template = gen.Template
 			break
 		}
 	}