Visual improvements to debug mode for better information visibility

src/shared/debug-body.js

@@ -0,0 +1,40 @@
+function createDebugBodyPreview(text, limit) {
+  if (text.length <= limit) return { value: text || "(empty response body)", truncated: false };
+  try {
+    const normalized = text.replace(/^\uFEFF/, "").trimStart()
+      .replace(/^\)\]\}',?\s*/, "").replace(/^while\s*\(1\);\s*/, "");
+    let value = JSON.parse(normalized);
+    for (let depth = 0; depth < 2 && typeof value === "string" && /^\s*[\[{]/.test(value); depth += 1) {
+      try { value = JSON.parse(value); } catch { break; }
+    }
+    // Bound retained data without cutting JSON syntax or losing sensitive field names.
+    let remaining = Math.max(0, limit - 256);
+    const visit = (node, depth = 0) => {
+      if (remaining <= 64 || depth >= 30) return "[omitted from debug preview]";
+      if (node === null || typeof node !== "object") {
+        const serialized = JSON.stringify(node);
+        if (serialized.length > remaining) {
+          remaining = 0;
+          return "[omitted from debug preview]";
+        }
+        remaining -= serialized.length + 1;
+        return node;
+      }
+      const result = Array.isArray(node) ? [] : Object.create(null);
+      remaining -= 2;
+      for (const key of Object.keys(node)) {
+        const cost = Array.isArray(node) ? 1 : JSON.stringify(key).length + 2;
+        if (remaining < cost + 64) break;
+        remaining -= cost;
+        result[key] = visit(node[key], depth + 1);
+      }
+      return result;
+    };
+    return {
+      value: JSON.stringify({ debugNotice: "Partial response preview: remaining fields/items omitted due to the debug size limit.", preview: visit(value) }),
+      truncated: true
+    };
+  } catch {
+    return { value: `${text.slice(0, limit)}\n... truncated ${text.length - limit} characters`, truncated: true };
+  }
+}