Revert "model : gpt-oss add response_format support (ggml-org#15494)"

This reverts commit 32732f2.

Author: Nexesenex

common/chat.cpp

@@ -1361,26 +1361,6 @@ static common_chat_params common_chat_params_init_gpt_oss(const common_chat_temp
         "<|end|>",
     };
 
-    if (!inputs.json_schema.is_null()) {
-        data.grammar_lazy = false;
-        data.grammar = build_grammar([&](const common_grammar_builder & builder) {
-            auto schema = inputs.json_schema;
-            builder.resolve_refs(schema);
-
-            auto not_end = builder.add_rule("not-end",
-                "[^<] | \"<\" [^|] | \"<|\" [^e] | \"<|e\" [^n] | \"<|en\" [^d] | \"<|end\" [^|] | \"<|end|\" [^>]");
-            auto analysis = builder.add_rule("analysis",
-                "\"<|channel|>analysis<|message|>\" ( " + not_end + " )* \"<|end|>\"");
-            auto constraint = builder.add_rule("constraint", "\"<|constrain|>\"? [a-zA-Z0-9_-]+");
-            auto final = builder.add_rule("final",
-                "\"<|channel|>final\" ( \" \" " + constraint + " )? \"<|message|>\" " +
-                builder.add_schema("response", schema)
-            );
-
-            builder.add_rule("root", "( " + analysis + " \"<|start|>assistant\" )? " + final);
-        });
-    }
-
     if (inputs.tools.is_array() && !inputs.tools.empty()) {
         data.grammar_lazy = inputs.tool_choice != COMMON_CHAT_TOOL_CHOICE_REQUIRED;
         data.grammar = build_grammar([&](const common_grammar_builder & builder) {
@@ -2141,7 +2121,7 @@ static common_chat_params common_chat_templates_apply_jinja(
     }
 
     // GPT-OSS
-    if (src.find("<|channel|>") != std::string::npos) {
+    if (src.find("<|channel|>") != std::string::npos && params.json_schema.is_null()) {
         return common_chat_params_init_gpt_oss(tmpl, params);
     }