model : add AfmoeForCausalLM support (#16477)

* Add AFMOE model support

* Update to vocab

* Add model sizing

* Undo Rope change for ARCEE model

* Address review comments

* Update modeling code is_sliding -> use_rope, replace hard-coded logic

* Fix AFMOE tokenizer

* Update convert_hf_to_gguf.py

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* Update convert_hf_to_gguf.py

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* Update AFMoE tokenizer class identification to be more unique

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

src/unicode.cpp

@@ -729,6 +729,80 @@ static std::vector<size_t> unicode_regex_split_custom_kimi_k2(const std::string
     return bpe_offsets;
 }
 
+// AFMOE digit handling: splits digits with leading 1-2 based on total length modulo 3
+static std::vector<size_t> unicode_regex_split_custom_afmoe(const std::string & text, const std::vector<size_t> & offsets) {
+    std::vector<size_t> bpe_offsets;
+    bpe_offsets.reserve(offsets.size());
+
+    const auto cpts = unicode_cpts_from_utf8(text);
+
+    size_t start = 0;
+    for (auto offset : offsets) {
+        const size_t offset_ini = start;
+        const size_t offset_end = start + offset;
+        assert(offset_end <= cpts.size());
+        start = offset_end;
+
+        auto _get_flags = [&] (const size_t pos) -> unicode_cpt_flags {
+            return (offset_ini <= pos && pos < offset_end) ? unicode_cpt_flags_from_cpt(cpts[pos]) : unicode_cpt_flags{};
+        };
+
+        size_t _prev_end = offset_ini;
+        auto _add_token = [&] (const size_t end) -> size_t {
+            assert(_prev_end <= end && end <= offset_end);
+            size_t len = end - _prev_end;
+            if (len > 0) {
+                bpe_offsets.push_back(len);
+            }
+            _prev_end = end;
+            return len;
+        };
+
+        for (size_t pos = offset_ini; pos < offset_end; ) {
+            const auto flags = _get_flags(pos);
+
+            // Handle digit sequences with special splitting logic
+            if (flags.is_number) {
+                size_t digit_start = pos;
+                size_t digit_count = 0;
+
+                // Count consecutive digits
+                while (_get_flags(pos).is_number && pos < offset_end) {
+                    digit_count++;
+                    pos++;
+                }
+
+                // Split based on total length modulo 3
+                size_t remainder = digit_count % 3;
+                size_t current = digit_start;
+
+                // Emit leading 1-2 digits if needed
+                if (remainder > 0) {
+                    _add_token(current + remainder);
+                    current += remainder;
+                }
+
+                // Emit groups of 3
+                while (current < digit_start + digit_count) {
+                    _add_token(current + 3);
+                    current += 3;
+                }
+                continue;
+            }
+
+            // For non-digits, just move forward
+            pos++;
+        }
+
+        // Add any remaining content
+        if (_prev_end < offset_end) {
+            _add_token(offset_end);
+        }
+    }
+
+    return bpe_offsets;
+}
+
 static std::vector<size_t> unicode_regex_split_custom(const std::string & text, const std::string & regex_expr, const std::vector<size_t> & offsets) {
     std::vector<size_t> bpe_offsets;
 
@@ -742,6 +816,9 @@ static std::vector<size_t> unicode_regex_split_custom(const std::string & text,
     } else if (regex_expr == "\\p{Han}+") {
         // K2's first pattern - handle all K2 patterns together
         bpe_offsets = unicode_regex_split_custom_kimi_k2(text, offsets);
+    } else if (regex_expr == "\\p{AFMoE_digits}") {
+        // AFMOE digit pattern - use custom implementation for proper splitting
+        bpe_offsets = unicode_regex_split_custom_afmoe(text, offsets);
     }
 
     return bpe_offsets;