Add titlecase marker injection

Author: apsonawane

operators/tokenizer/ugm_kernels.hpp

@@ -563,6 +563,9 @@ struct SpmUgmTokenizer {
 
     std::string_view input_view(input);
     int consumed = 0;
+    size_t original_index = 0;
+    bool pending_title_marker = false;
+    bool pending_upper_marker = false;
 
     while (!input_view.empty()) {
       auto p = case_encoder_->NormalizePrefix(input_view);
@@ -576,6 +579,38 @@ struct SpmUgmTokenizer {
               normalized.append(space);
               is_space_prepended = true;
             }
+
+            // Detect Titlecase/Acronym at the start of a word using original input (ASCII heuristic)
+            // Titlecase: first letter uppercase followed by lowercase
+            // Acronym: 2+ consecutive uppercase letters
+            auto is_upper_ascii = [](unsigned char ch) { return ch >= 'A' && ch <= 'Z'; };
+            auto is_lower_ascii = [](unsigned char ch) { return ch >= 'a' && ch <= 'z'; };
+            size_t idx = original_index;
+            while (idx < input.size() && (input[idx] == ' ' || input[idx] == '\t' || input[idx] == '\n' || input[idx] == '\r')) idx++;
+            if (idx < input.size() && is_upper_ascii(static_cast<unsigned char>(input[idx]))) {
+              size_t j = idx;
+              size_t upper_count = 0;
+              while (j < input.size() && is_upper_ascii(static_cast<unsigned char>(input[j]))) {
+                ++upper_count;
+                ++j;
+              }
+              if (upper_count >= 2) {
+                pending_upper_marker = true;
+              } else if (upper_count == 1) {
+                if (j < input.size() && is_lower_ascii(static_cast<unsigned char>(input[j]))) {
+                  pending_title_marker = true;
+                }
+              }
+            }
+          }
+          if (pending_upper_marker) {
+            // Insert All-Uppercase marker before the first non-space char of the word
+            normalized.push_back(normalizer::cAllUppercase);
+            pending_upper_marker = false;
+          } else if (pending_title_marker) {
+            // Insert Titlecase marker before the first non-space char of the word
+            normalized.push_back(normalizer::cTitlecase);
+            pending_title_marker = false;
           }
           normalized.push_back(c);
         } else {
@@ -590,6 +625,7 @@ struct SpmUgmTokenizer {
 
       consumed += p.second;
       input_view.remove_prefix(p.second);
+      original_index += static_cast<size_t>(p.second);
     }
 
     case_encoder_->PostProcess(&normalized, &norm_to_orig);