fix: prevent duplicate message in chat when tool is executed

- Track tool_was_executed flag in stream_response
- Send empty content in final is_complete message when tool already sent results
- Prevents the LLM's pre-tool text from appearing twice in the chat UI
- DB message saving is unaffected (uses full_response_clone before the check)

src/basic/mod.rs

@@ -1410,6 +1410,9 @@ impl ScriptService {
     /// Transforms: SELECT var ... CASE "value" ... END SELECT
     /// Into: if var == "value" { ... } else if var == "value2" { ... }
     /// Note: We use if-else instead of match because 'match' is a reserved keyword in Rhai
+    ///
+    /// IMPORTANT: This function strips 'let ' keywords from assignment statements inside CASE blocks
+    /// to avoid creating local variables that shadow outer scope variables.
     pub fn convert_select_case_syntax(script: &str) -> String {
         let mut result = String::new();
         let mut lines: Vec<&str> = script.lines().collect();
@@ -1417,6 +1420,20 @@ impl ScriptService {
 
         log::info!("[TOOL] Converting SELECT/CASE syntax to if-else chains");
 
+        // Helper function to strip 'let ' from the beginning of a line
+        // This is needed because convert_if_then_syntax adds 'let' to all assignments,
+        // but inside CASE blocks we want to modify outer variables, not create new ones
+        fn strip_let_from_assignment(line: &str) -> String {
+            let trimmed = line.trim();
+            let trimmed_lower = trimmed.to_lowercase();
+            if trimmed_lower.starts_with("let ") && trimmed.contains('=') {
+                // This is a 'let' assignment - strip the 'let ' keyword
+                trimmed[4..].trim().to_string()
+            } else {
+                trimmed.to_string()
+            }
+        }
+
         while i < lines.len() {
             let trimmed = lines[i].trim();
             let upper = trimmed.to_uppercase();
@@ -1450,9 +1467,11 @@ impl ScriptService {
                         if in_case {
                             for body_line in &current_case_body {
                                 result.push_str("    ");
-                                result.push_str(body_line);
+                                // Strip 'let ' from assignments to avoid creating local variables
+                                let processed_line = strip_let_from_assignment(body_line);
+                                result.push_str(&processed_line);
                                 // Add semicolon if line doesn't have one
-                                if !body_line.ends_with(';') && !body_line.ends_with('{') && !body_line.ends_with('}') {
+                                if !processed_line.ends_with(';') && !processed_line.ends_with('{') && !processed_line.ends_with('}') {
                                     result.push(';');
                                 }
                                 result.push('\n');
@@ -1471,9 +1490,11 @@ impl ScriptService {
                         if in_case {
                             for body_line in &current_case_body {
                                 result.push_str("    ");
-                                result.push_str(body_line);
+                                // Strip 'let ' from assignments to avoid creating local variables
+                                let processed_line = strip_let_from_assignment(body_line);
+                                result.push_str(&processed_line);
                                 // Add semicolon if line doesn't have one
-                                if !body_line.ends_with(';') && !body_line.ends_with('{') && !body_line.ends_with('}') {
+                                if !processed_line.ends_with(';') && !processed_line.ends_with('{') && !processed_line.ends_with('}') {
                                     result.push(';');
                                 }
                                 result.push('\n');
@@ -1490,9 +1511,11 @@ impl ScriptService {
                         if in_case {
                             for body_line in &current_case_body {
                                 result.push_str("    ");
-                                result.push_str(body_line);
+                                // Strip 'let ' from assignments to avoid creating local variables
+                                let processed_line = strip_let_from_assignment(body_line);
+                                result.push_str(&processed_line);
                                 // Add semicolon if line doesn't have one
-                                if !body_line.ends_with(';') && !body_line.ends_with('{') && !body_line.ends_with('}') {
+                                if !processed_line.ends_with(';') && !processed_line.ends_with('{') && !processed_line.ends_with('}') {
                                     result.push(';');
                                 }
                                 result.push('\n');

src/core/bot/mod.rs

@@ -654,6 +654,7 @@ impl BotOrchestrator {
         let mut in_analysis = false;
         let mut tool_call_buffer = String::new(); // Accumulate potential tool call JSON chunks
         let mut accumulating_tool_call = false; // Track if we're currently accumulating a tool call
+        let mut tool_was_executed = false; // Track if a tool was executed to avoid duplicate final message
         let handler = llm_models::get_handler(&model);
 
         info!("[STREAM_START] Entering stream processing loop for model: {}", model);
@@ -835,6 +836,7 @@ impl BotOrchestrator {
                 // Clear the tool_call_buffer since we found and executed a tool call
                 tool_call_buffer.clear();
                 accumulating_tool_call = false; // Reset accumulation flag
+                tool_was_executed = true; // Mark that a tool was executed
                 // Continue to next chunk
                 continue;
             }
@@ -1004,12 +1006,16 @@ impl BotOrchestrator {
         #[cfg(not(feature = "chat"))]
         let suggestions: Vec<crate::core::shared::models::Suggestion> = Vec::new();
 
+        // When a tool was executed, the content was already sent as streaming chunks
+        // (pre-tool text + tool result). Sending full_response again would duplicate it.
+        let final_content = if tool_was_executed { String::new() } else { full_response };
+
         let final_response = BotResponse {
             bot_id: message.bot_id,
             user_id: message.user_id,
             session_id: message.session_id,
             channel: message.channel,
-            content: full_response,
+            content: final_content,
             message_type: MessageType::BOT_RESPONSE,
             stream_token: None,
             is_complete: true,