diff --git a/common/chat.cpp b/common/chat.cpp
index 6da59f4dbd..22d2ee4a2a 100644
--- a/common/chat.cpp
+++ b/common/chat.cpp
@@ -2378,6 +2378,23 @@ static void func_args_not_string(json & messages) {
     }
 }
 
+// Trim leading/trailing whitespace from message contents before rendering. This
+// has to run on the messages (not on the rendered JSON) because templates with
+// string-only content caps concatenate typed content parts into a single string
+// during rendering, after which the per-part whitespace can no longer be reached.
+// Both the plain string content and the text of typed content parts are trimmed.
+static void trim_all_content(std::vector<common_chat_msg> & messages) {
+    for (auto & message : messages) {
+        message.content           = trim_whitespace(message.content);
+        message.reasoning_content = trim_whitespace(message.reasoning_content);
+        for (auto & part : message.content_parts) {
+            if (part.type == "text") {
+                part.text = trim_whitespace(part.text);
+            }
+        }
+    }
+}
+
 }
 
 // MiniCPM5 format:
@@ -2634,7 +2651,16 @@ static common_chat_params common_chat_templates_apply_jinja(const struct common_
         params.tools.is_array() && tmpls->template_tool_use ? *tmpls->template_tool_use : *tmpls->template_default;
     const auto & src             = tmpl.source();
     const auto & caps            = tmpl.original_caps();
-    params.messages              = render_message_to_json(inputs.messages, tmpl.original_caps());
+    std::vector<common_chat_msg>        trimmed_messages;
+    const std::vector<common_chat_msg> * messages_to_render = &inputs.messages;
+    if (src.find("You have access to the following functions in JSONSchema format") != std::string::npos) {
+        // StepFun: trim message contents (including typed content parts) before rendering,
+        // otherwise leftover whitespace drives the model into reasoning loops (issue #24181)
+        trimmed_messages   = inputs.messages;
+        workaround::trim_all_content(trimmed_messages);
+        messages_to_render = &trimmed_messages;
+    }
+    params.messages              = render_message_to_json(*messages_to_render, tmpl.original_caps());
     params.tool_choice           = inputs.tool_choice;
     params.reasoning_format      = inputs.reasoning_format;
     params.enable_thinking       = inputs.enable_thinking;
diff --git a/models/templates/stepfun-ai-Step-3.5-Flash.jinja b/models/templates/stepfun-ai-Step-3.5-Flash.jinja
deleted file mode 100644
index c09ea497da..0000000000
--- a/models/templates/stepfun-ai-Step-3.5-Flash.jinja
+++ /dev/null
@@ -1,80 +0,0 @@
-{% macro render_content(content) %}{% if content is none %}{{- '' }}{% elif content is string %}{{- content }}{% elif content is mapping %}{{- content['value'] if 'value' in content else content['text'] }}{% elif content is iterable %}{% for item in content %}{% if item.type == 'text' %}{{- item['value'] if 'value' in item else item['text'] }}{% elif item.type == 'image' %}<im_patch>{% endif %}{% endfor %}{% endif %}{% endmacro %}
-{{bos_token}}{%- if tools %}
-    {{- '<|im_start|>system\n' }}
-    {%- if messages[0].role == 'system' %}
-        {{- render_content(messages[0].content) + '\n\n' }}
-    {%- endif %}
-    {{- "# Tools\n\nYou have access to the following functions in JSONSchema format:\n\n<tools>" }}
-    {%- for tool in tools %}
-        {{- "\n" }}
-        {{- tool | tojson(ensure_ascii=False) }}
-    {%- endfor %}
-    {{- "\n</tools>\n\nIf you choose to call a function ONLY reply in the following format with NO suffix:\n\n<tool_call>\n<function=example_function_name>\n<parameter=example_parameter_1>\nvalue_1\n</parameter>\n<parameter=example_parameter_2>\nThis is the value for the second parameter\nthat can span\nmultiple lines\n</parameter>\n</function>\n</tool_call>\n\n<IMPORTANT>\nReminder:\n- Function calls MUST follow the specified format: an inner <function=...>\n...\n</function> block must be nested within <tool_call>\n...\n</tool_call> XML tags\n- Required parameters MUST be specified\n</IMPORTANT><|im_end|>\n" }}
-{%- else %}
-    {%- if messages[0].role == 'system' %}
-        {{- '<|im_start|>system\n' + render_content(messages[0].content) + '<|im_end|>\n' }}
-    {%- endif %}
-{%- endif %}
-{%- set ns = namespace(multi_step_tool=true, last_query_index=messages|length - 1) %}
-{%- for message in messages[::-1] %}
-    {%- set index = (messages|length - 1) - loop.index0 %}
-    {%- if ns.multi_step_tool and message.role == "user" and render_content(message.content) is string and not(render_content(message.content).startswith('<tool_response>') and render_content(message.content).endswith('</tool_response>')) %}
-        {%- set ns.multi_step_tool = false %}
-        {%- set ns.last_query_index = index %}
-    {%- endif %}
-{%- endfor %}
-{%- for message in messages %}
-    {%- set content = render_content(message.content) %}
-    {%- if (message.role == "user") or (message.role == "system" and not loop.first) %}
-        {%- set role_name = 'observation' if (message.role == "system" and not loop.first and message.name == 'observation') else message.role %}
-        {{- '<|im_start|>' + role_name + '\n' + content + '<|im_end|>' + '\n' }}
-    {%- elif message.role == "assistant" %}
-        {%- if message.reasoning_content is string %}
-            {%- set reasoning_content = render_content(message.reasoning_content) %}
-        {%- else %}
-            {%- if '</think>' in content %}
-                {%- set reasoning_content = content.split('</think>')[0].rstrip('\n').split('<think>')[-1].lstrip('\n') %}
-                {%- set content = content.split('</think>')[-1].lstrip('\n') %}
-            {%- else %}
-                {%- set reasoning_content = '' %}
-            {%- endif %}
-        {%- endif %}
-        {%- if loop.index0 > ns.last_query_index %}
-            {{- '<|im_start|>' + message.role + '\n<think>\n' + reasoning_content + '\n</think>\n' + content }}
-        {%- else %}
-            {{- '<|im_start|>' + message.role + '\n' + content }}
-        {%- endif %}
-        {%- if message.tool_calls %}
-            {%- for tool_call in message.tool_calls %}
-                {%- if tool_call.function is defined %}
-                    {%- set tool_call = tool_call.function %}
-                {%- endif %}
-                {{- '<tool_call>\n<function=' + tool_call.name + '>\n' }}
-                {%- if tool_call.arguments is defined %}
-                    {%- set arguments = tool_call.arguments %}
-                    {%- for args_name, args_value in arguments|items %}
-                        {{- '<parameter=' + args_name + '>\n' }}
-                        {%- set args_value = args_value | tojson(ensure_ascii=False) | safe if args_value is mapping or (args_value is sequence and args_value is not string) else args_value | string %}
-                        {{- args_value }}
-                        {{- '\n</parameter>\n' }}
-                    {%- endfor %}
-                {%- endif %}
-                {{- '</function>\n</tool_call>' }}
-            {%- endfor %}
-        {%- endif %}
-        {{- '<|im_end|>\n' }}
-    {%- elif message.role == "tool" %}
-        {%- if loop.first or (messages[loop.index0 - 1].role != "tool") %}
-            {{- '<|im_start|>tool_response\n' }}
-        {%- endif %}
-        {{- '<tool_response>' }}
-        {{- content }}
-        {{- '</tool_response>' }}
-        {%- if loop.last or (messages[loop.index0 + 1].role != "tool") %}
-            {{- '<|im_end|>\n' }}
-        {%- endif %}
-    {%- endif %}
-{%- endfor %}
-{%- if add_generation_prompt %}
-    {{- '<|im_start|>assistant\n<think>\n' }}
-{%- endif %}
diff --git a/tests/test-chat-auto-parser.cpp b/tests/test-chat-auto-parser.cpp
index 5cc1057532..d15fdd2c02 100644
--- a/tests/test-chat-auto-parser.cpp
+++ b/tests/test-chat-auto-parser.cpp
@@ -1887,7 +1887,6 @@ static void test_role_markers_all_templates(testing & t) {
         { "Qwen-Qwen3-0.6B.jinja",                           "<|im_start|>user",       "<|im_start|>assistant"      },
         { "Qwen-QwQ-32B.jinja",                              "<|im_start|>user",       "<|im_start|>assistant"      },
         { "StepFun3.5-Flash.jinja",                          "<|im_start|>user",       "<|im_start|>assistant"      },
-        { "stepfun-ai-Step-3.5-Flash.jinja",                 "<|im_start|>user",       "<|im_start|>assistant"      },
 
         // DeepSeek family
         { "deepseek-ai-DeepSeek-R1-Distill-Llama-8B.jinja",  "<｜User｜>",                "<｜Assistant｜>"             },
diff --git a/tests/test-chat.cpp b/tests/test-chat.cpp
index 5f71e5da6e..e1e0a59e6d 100644
--- a/tests/test-chat.cpp
+++ b/tests/test-chat.cpp
@@ -3155,6 +3155,59 @@ static void test_template_output_peg_parsers(bool detailed_debug) {
                 }
             }
         }
+
+        {
+            // StepFun trimming regression test (see https://github.com/ggml-org/llama.cpp/pull/25238)
+            auto tmpls = read_templates("models/templates/StepFun3.5-Flash.jinja");
+
+            common_chat_msg message_chatbot = simple_assist_msg("Let me check.\n\n", "I am thinking.\n\n");
+
+            {
+                common_chat_templates_inputs inputs;
+                inputs.messages              = { message_chatbot };
+                inputs.add_generation_prompt = true;
+
+                auto params = common_chat_templates_apply(tmpls.get(), inputs);
+
+                if (params.prompt.find("Let me check.\n\n") != std::string::npos) {
+                    throw std::runtime_error("StepFun 3.5: content not trimmed");
+                }
+
+                if (params.prompt.find("I am thinking.\n\n") != std::string::npos) {
+                    throw std::runtime_error("StepFun 3.5: reasoning_content not trimmed");
+                }
+            }
+
+            {
+                // Trimming must also reach typed (text) content parts, not just string content
+                // (see https://github.com/ggml-org/llama.cpp/pull/25238)
+                common_chat_msg message_parts;
+                message_parts.role          = "user";
+                message_parts.content_parts = {
+                    { /* .type = */ "text", /* .text = */ "First part.\n\n" },
+                    { /* .type = */ "media_marker", /* .text = */ "<__media__>" },
+                    { /* .type = */ "text", /* .text = */ "Second part.\n\n" },
+                };
+
+                common_chat_templates_inputs inputs;
+                inputs.messages              = { message_parts };
+                inputs.add_generation_prompt = true;
+
+                auto params = common_chat_templates_apply(tmpls.get(), inputs);
+
+                if (params.prompt.find("First part.\n\n") != std::string::npos ||
+                    params.prompt.find("Second part.\n\n") != std::string::npos) {
+                    throw std::runtime_error("StepFun 3.5: text content parts not trimmed");
+                }
+
+                // the trimmed text itself must still be present
+                if (params.prompt.find("First part.") == std::string::npos ||
+                    params.prompt.find("Second part.") == std::string::npos) {
+                    throw std::runtime_error("StepFun 3.5: text content parts missing after trim");
+                }
+            }
+        }
+
     }
 
     {