Enhance bash tool output handling

- Add 30KB output truncation with clear message when exceeded
- Display '<system>Tool ran without output or errors</system>' for successful commands with no output
- Improve error handling for commands that fail with no output
- Better user experience for both edge cases

This helps prevent overwhelming the UI with large outputs and clearly indicates
when commands succeed silently.

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

Author: Keno

src/tools/bash.jl

@@ -140,36 +140,64 @@ function execute(tool::BashTool, params::Dict)
         stdout_str = String(take!(stdout_buf))
         stderr_str = String(take!(stderr_buf))
         exit_code = proc.exitcode
-        
+
+        # Truncate output if needed (30KB = 30720 bytes)
+        max_output_bytes = 30720
+        truncated = false
+
+        # Check and truncate stdout
+        if sizeof(stdout_str) > max_output_bytes
+            stdout_str = String(codeunits(stdout_str)[1:max_output_bytes])
+            truncated = true
+        end
+
+        # Check and truncate stderr (allow some space for both)
+        stderr_max = max(1024, max_output_bytes - sizeof(stdout_str))  # At least 1KB for stderr
+        if sizeof(stderr_str) > stderr_max
+            stderr_str = String(codeunits(stderr_str)[1:stderr_max])
+            truncated = true
+        end
+
         # Format the response
         response_parts = String[]
-        
+
         # Add stdout if not empty
         if !isempty(stdout_str)
             push!(response_parts, stdout_str)
         end
-        
+
         # Add stderr if not empty (prefix it to distinguish)
         if !isempty(stderr_str)
             if !isempty(response_parts)
                 push!(response_parts, "\n--- stderr ---\n")
             end
             push!(response_parts, stderr_str)
         end
-        
+
+        # Add truncation notice if output was truncated
+        if truncated
+            if !isempty(response_parts)
+                push!(response_parts, "\n")
+            end
+            push!(response_parts, "--- Output truncated (exceeded 30KB limit) ---")
+        end
+
         # Add exit code if non-zero
         if exit_code != 0
             if !isempty(response_parts)
                 push!(response_parts, "\n")
             end
             push!(response_parts, "Exit code: $exit_code")
         end
-        
-        # If no output at all, indicate success
-        if isempty(response_parts)
-            push!(response_parts, "Command completed successfully (no output)")
+
+        # If no output at all and success, use special format
+        if isempty(response_parts) && exit_code == 0
+            push!(response_parts, "<system>Tool ran without output or errors</system>")
+        elseif isempty(response_parts)
+            # Had an error but no output
+            push!(response_parts, "Command failed with exit code: $exit_code (no output)")
         end
-        
+
         result_text = join(response_parts)
 
         # Return success - non-zero exit codes are part of normal command output, not MCP errors