chat : enable tool call in thinking for DS4 (#26269)

tests/test-chat.cpp

@@ -4227,6 +4227,20 @@ static void test_template_output_peg_parsers(bool detailed_debug) {
             .expect_reasoning("I'm thinking")
             .expect_content("Hello, world!\nWhat's up?")
             .run();
+
+        tst.test(
+            "Let me check the time\n\n"
+            "<｜DSML｜tool_calls>\n"
+            "<｜DSML｜invoke name=\"get_time\">\n"
+            "<｜DSML｜parameter name=\"city\" string=\"true\">Tokyo</｜DSML｜parameter>\n"
+            "</｜DSML｜invoke>\n"
+            "</｜DSML｜tool_calls>") // no </think> after the TC close because the grammar will immediately constrain it to end
+            .enable_thinking(true)
+            .reasoning_format(COMMON_REASONING_FORMAT_DEEPSEEK)
+            .tools({ get_time_tool })
+            .expect_reasoning("Let me check the time")
+            .expect_tool_calls({ { "get_time", R"({"city": "Tokyo"})", {} } })
+            .run();
     }
 
     // GLM-4.6 tests - format: <tool_call>function_name\n<arg_key>...</arg_key>\n<arg_value>...</arg_value>\n</tool_call>