From 06df0795c80b17c1366522c45de24cb01bf9d8a3 Mon Sep 17 00:00:00 2001
From: jaberjaber23 <jaberib647@gmail.com>
Date: Thu, 5 Mar 2026 15:41:08 +0300
Subject: [PATCH] think stripping

---
 crates/openfang-api/src/openai_compat.rs |  2 +-
 crates/openfang-api/src/routes.rs        |  7 ++--
 crates/openfang-api/src/ws.rs            | 43 ++++++++++++++++++++++--
 3 files changed, 47 insertions(+), 5 deletions(-)

diff --git a/crates/openfang-api/src/openai_compat.rs b/crates/openfang-api/src/openai_compat.rs
index 884add98..a0e806c6 100644
--- a/crates/openfang-api/src/openai_compat.rs
+++ b/crates/openfang-api/src/openai_compat.rs
@@ -335,7 +335,7 @@ pub async fn chat_completions(
                     index: 0,
                     message: ChoiceMessage {
                         role: "assistant",
-                        content: Some(result.response),
+                        content: Some(crate::ws::strip_think_tags(&result.response)),
                         tool_calls: None,
                     },
                     finish_reason: "stop",
diff --git a/crates/openfang-api/src/routes.rs b/crates/openfang-api/src/routes.rs
index bcf5c6ca..29198ace 100644
--- a/crates/openfang-api/src/routes.rs
+++ b/crates/openfang-api/src/routes.rs
@@ -321,8 +321,11 @@ pub async fn send_message(
         .await
     {
         Ok(result) => {
+            // Strip <think>...</think> blocks from model output
+            let cleaned = crate::ws::strip_think_tags(&result.response);
+
             // Guard: ensure we never return an empty response to the client
-            let response = if result.response.trim().is_empty() {
+            let response = if cleaned.trim().is_empty() {
                 format!(
                     "[The agent completed processing but returned no text response. ({} in / {} out | {} iter)]",
                     result.total_usage.input_tokens,
@@ -330,7 +333,7 @@ pub async fn send_message(
                     result.iterations,
                 )
             } else {
-                result.response
+                cleaned
             };
             (
                 StatusCode::OK,
diff --git a/crates/openfang-api/src/ws.rs b/crates/openfang-api/src/ws.rs
index 6b6a526e..19ff864f 100644
--- a/crates/openfang-api/src/ws.rs
+++ b/crates/openfang-api/src/ws.rs
@@ -621,8 +621,12 @@ async fn handle_text_message(
                                 return;
                             }
 
+                            // Strip <think>...</think> blocks from model output
+                            // (e.g. MiniMax, DeepSeek reasoning tokens)
+                            let cleaned_response = strip_think_tags(&result.response);
+
                             // Guard: ensure we never send an empty response
-                            let content = if result.response.trim().is_empty() {
+                            let content = if cleaned_response.trim().is_empty() {
                                 format!(
                                     "[The agent completed processing but returned no text response. ({} in / {} out | {} iter)]",
                                     result.total_usage.input_tokens,
@@ -630,7 +634,7 @@ async fn handle_text_message(
                                     result.iterations,
                                 )
                             } else {
-                                result.response
+                                cleaned_response
                             };
 
                             // Estimate context pressure from last call
@@ -1156,6 +1160,27 @@ fn extract_status_code(s: &str) -> Option<u16> {
     None
 }
 
+/// Strip `<think>...</think>` blocks from model output.
+///
+/// Some models (MiniMax, DeepSeek, etc.) wrap their reasoning in `<think>` tags.
+/// These are internal chain-of-thought and shouldn't be shown to the user.
+pub fn strip_think_tags(text: &str) -> String {
+    let mut result = String::with_capacity(text.len());
+    let mut remaining = text;
+    while let Some(start) = remaining.find("<think>") {
+        result.push_str(&remaining[..start]);
+        if let Some(end) = remaining[start..].find("</think>") {
+            remaining = &remaining[(start + end + 8)..]; // 8 = "</think>".len()
+        } else {
+            // Unclosed <think> tag — strip to end
+            remaining = "";
+            break;
+        }
+    }
+    result.push_str(remaining);
+    result
+}
+
 // ---------------------------------------------------------------------------
 // Tests
 // ---------------------------------------------------------------------------
@@ -1232,4 +1257,18 @@ mod tests {
     fn test_sanitize_trims_whitespace() {
         assert_eq!(sanitize_user_input("  hello  "), "hello");
     }
+
+    #[test]
+    fn test_strip_think_tags() {
+        assert_eq!(
+            strip_think_tags("<think>reasoning here</think>The answer is 42."),
+            "The answer is 42."
+        );
+        assert_eq!(
+            strip_think_tags("Hello <think>\nsome thinking\n</think> world"),
+            "Hello  world"
+        );
+        assert_eq!(strip_think_tags("No thinking here"), "No thinking here");
+        assert_eq!(strip_think_tags("<think>all thinking</think>"), "");
+    }
 }