fix(acp): avoid duplicate thought chunks around tool calls (#8215)

Signed-off-by: Kevin Lam <kevklam@users.noreply.github.com>

crates/goose/src/agents/agent.rs

@@ -395,10 +395,12 @@ impl Agent {
         &self,
         response: &Message,
         tools: &[rmcp::model::Tool],
+        suppress_replayed_thinking: bool,
     ) -> ToolCategorizeResult {
         // Categorize tool requests
-        let (frontend_requests, remaining_requests, filtered_response) =
-            self.categorize_tool_requests(response, tools).await;
+        let (frontend_requests, remaining_requests, filtered_response) = self
+            .categorize_tool_requests(response, tools, suppress_replayed_thinking)
+            .await;
 
         ToolCategorizeResult {
             frontend_requests,
@@ -1224,6 +1226,11 @@ impl Agent {
                 let mut did_recovery_compact_this_iteration = false;
                 let mut exit_chat = false;
 
+                // Track whether this provider turn has already emitted visible
+                // thinking so a later tool-call chunk can suppress replayed
+                // reasoning without hiding final-only non-streaming thoughts.
+                let mut surfaced_thinking_in_turn = false;
+
                 while let Some(next) = stream.next().await {
                     if is_token_cancelled(&cancel_token) || exit_chat {
                         break;
@@ -1242,7 +1249,23 @@ impl Agent {
                                     frontend_requests,
                                     remaining_requests,
                                     filtered_response,
-                                } = self.categorize_tools(&response, &tools).await;
+                                } = self
+                                    .categorize_tools(
+                                        &response,
+                                        &tools,
+                                        surfaced_thinking_in_turn,
+                                    )
+                                    .await;
+
+                                surfaced_thinking_in_turn |= filtered_response.content.iter().any(
+                                    |content| {
+                                        matches!(
+                                            content,
+                                            MessageContent::Thinking(_)
+                                                | MessageContent::RedactedThinking(_)
+                                        )
+                                    },
+                                );
 
                                 yield AgentEvent::Message(filtered_response.clone());
                                 tokio::task::yield_now().await;

crates/goose/src/agents/reply_parts.rs

@@ -339,6 +339,7 @@ impl Agent {
         &self,
         response: &Message,
         tools: &[Tool],
+        suppress_replayed_thinking: bool,
     ) -> (Vec<ToolRequest>, Vec<ToolRequest>, Message) {
         // First collect all tool requests with coercion applied
         let tool_requests: Vec<ToolRequest> = response
@@ -367,7 +368,16 @@ impl Agent {
             })
             .collect();
 
-        // Create a filtered message with frontend tool requests removed
+        let has_tool_requests = !tool_requests.is_empty();
+        let should_suppress_replayed_thinking = suppress_replayed_thinking && has_tool_requests;
+
+        // Create a filtered message with frontend tool requests removed.
+        // When a response contains tool calls, keep reasoning in the original
+        // message for provider/state purposes but only suppress it from the
+        // user-visible filtered message if the caller already surfaced
+        // thinking earlier in this provider turn. That avoids replaying full
+        // accumulated reasoning after streamed thought chunks while still
+        // preserving final-only non-streaming thoughts.
         let mut filtered_content = Vec::new();
         let mut tool_request_index = 0;
 
@@ -389,6 +399,8 @@ impl Agent {
                         }
                     }
                 }
+                MessageContent::Thinking(_) | MessageContent::RedactedThinking(_)
+                    if should_suppress_replayed_thinking => {}
                 _ => {
                     filtered_content.push(content.clone());
                 }
@@ -662,6 +674,52 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    async fn categorize_tool_requests_keeps_thinking_when_not_previously_streamed() {
+        let agent = crate::agents::Agent::new();
+        let response = Message::assistant()
+            .with_thinking("final-only reasoning", "")
+            .with_tool_request(
+                "tool-1",
+                Ok(rmcp::model::CallToolRequestParams::new("test_tool")),
+            );
+
+        let (_frontend_requests, other_requests, filtered_message) =
+            agent.categorize_tool_requests(&response, &[], false).await;
+
+        assert_eq!(other_requests.len(), 1);
+        assert_eq!(filtered_message.content.len(), 2);
+        assert!(matches!(
+            filtered_message.content[0],
+            MessageContent::Thinking(_)
+        ));
+        assert!(matches!(
+            filtered_message.content[1],
+            MessageContent::ToolRequest(_)
+        ));
+    }
+
+    #[tokio::test]
+    async fn categorize_tool_requests_drops_replayed_thinking_after_streaming() {
+        let agent = crate::agents::Agent::new();
+        let response = Message::assistant()
+            .with_thinking("replayed reasoning", "")
+            .with_tool_request(
+                "tool-1",
+                Ok(rmcp::model::CallToolRequestParams::new("test_tool")),
+            );
+
+        let (_frontend_requests, other_requests, filtered_message) =
+            agent.categorize_tool_requests(&response, &[], true).await;
+
+        assert_eq!(other_requests.len(), 1);
+        assert_eq!(filtered_message.content.len(), 1);
+        assert!(matches!(
+            filtered_message.content[0],
+            MessageContent::ToolRequest(_)
+        ));
+    }
+
     fn make_tool_with_meta(meta_json: Option<serde_json::Value>) -> Tool {
         let mut tool = Tool::new("test_tool", "a test tool", object!({ "type": "object" }));
         if let Some(v) = meta_json {