diff --git a/src/agentCore.jl b/src/agentCore.jl
index 5c2cc74..199e785 100644
--- a/src/agentCore.jl
+++ b/src/agentCore.jl
@@ -269,22 +269,26 @@ function _agentLoop(agent::yiemAgent)
         else
           # check followUp message after _processMessage() is done
           if typeof(processingTask) == Task && istaskdone(processingTask) == true
+            # agent.eventSink("_processMessage() done")
             # if agent runs is done but followUpChannel has messages,
             # put new message in inputChannel instead
             if isready(agent.followUpChannel)
               while isready(agent.followUpChannel)
+                # agent.eventSink("put followUp message to input channel")
                 followUpMsg = take!(agent.followUpChannel)
                 put!(agent.inputChannel, followUpMsg)
               end
               processingTask = nothing        # reset
               result = nothing                # reset
             else  # _processMessage() done and no followUp message.
+              # agent.eventSink("no followUp message")
               result = deepcopy(agent._state.messages[end])
               # filter out reasoningContent in-place
               filter!(c -> !(c isa reasoningContent), result.content)
               # format output
               respondToUI = _assistantMessageToOpenAI(result)
               put!(agent.outputChannel, respondToUI)
+              # agent.eventSink("put result to output channel")
               processingTask = nothing        # reset
               result = nothing                # reset
             end
@@ -344,7 +348,7 @@ function _agentLoop(agent::yiemAgent)
         showerror(io, e, bt)
         println(io)
     end
-    eventSink(errMsg; publish=true)
+    # agent.eventSink(errMsg; publish=true)
 
     # On any error, send error response and exit the loop
     @error "Agent loop failed" error=e
@@ -395,6 +399,8 @@ function _processMessage(
   # loop until llmCall() response didn't use tool calls
   final_response = nothing
 
+  # eventSink("▶ _processMessage: entered")
+
   """ example message in inputChannel
   Dict(
       "role" => "user",
@@ -420,6 +426,7 @@ function _processMessage(
         end
         newUserMsg = OpenAiToUserMessage(newUserMsg_openai)
         push!(agentMsgHistory, newUserMsg)
+        # eventSink("▶ _processMessage: user msg pushed")
       end
       # call prepareContext()
       state = agentState(systemPrompt, nothing, tools, agentMsgHistory)
@@ -427,19 +434,22 @@ function _processMessage(
       # Call formatMessagesForLLM() to format for LLM
       formattedMessages = formatMessagesForLLM(preparedContext, eventSink)
 
-      eventSink("Thinking...")
+      # eventSink("▶ _processMessage: context")
       """ response example
       response = JSON.Object{String, Any}("finish_reason" => "tool_calls", "index" => 0, "message" => JSON.Object{String, Any}("role" => "assistant", "content" => "", "reasoning_content" => "Here's a thinking process:\n\n1.  **Identify User Request**: The user is asking for the weather in Bangkok.\n2.  **Locate Relevant Tool**: I have a `getWeather` function available.\n3.  **Check Function Parameters**:\n   - `city` (required): City and country, e.g., 'San Francisco, CA' or 'Tokyo, Japan'\n   - `units` (optional, default \"celsius\"): Temperature scale (\"celsius\" or \"fahrenheit\")\n4.  **Prepare Parameters**:\n   - `city`: \"Bangkok, Thailand\" (adding country for clarity, though just \"Bangkok\" might work, following the example format is safer)\n   - `units`: Not specified, so I'll use the default (\"celsius\")\n5.  **Execute Tool Call**: Call `getWeather` with `city: \"Bangkok, Thailand\"`\n6.  **Anticipate Response**: The function will return current weather and forecast data for Bangkok. I'll then format it nicely for the user.\n   - *Self-Correction/Verification during thought*: The prompt says \"city: City and country, e.g., 'San Francisco, CA' or 'Tokyo, Japan'\". I'll use \"Bangkok, Thailand\". The `units` parameter is optional, so I'll omit it to use the default.\n   - Proceed with tool call.✅\n", "tool_calls" => Any[JSON.Object{String, Any}("type" => "function", "function" => JSON.Object{String, Any}("name" => "getWeather", "arguments" => "{\"city\":\"Bangkok, Thailand\"}"), "id" => "6fOilR5QPcdppbAAHluhkRyUDu3oWMAL")]))
       """
       response = llmCall(formattedMessages, eventSink=eventSink)
 
       # Extract tool calls from LLM response content blocks
-      hasToolCalls, toolCallList, assistant_msg = _extractToolCalls(response)
+      hasToolCalls, toolCallList, assistant_msg = _extractToolCalls(response, eventSink)
 
       # Add assistant message (tool calls or text) to history for next LLM turn
       push!(agentMsgHistory, assistant_msg)
+      # eventSink("▶ _processMessage: LLM response")
 
       if hasToolCalls && length(toolCallList) > 0
+        # eventSink("▶ _processMessage: tool calls")
+
         # Build context and config for executeToolCalls
 
         config = agentLoopConfig(
@@ -452,11 +462,13 @@ function _processMessage(
         # call executeToolCalls()
         toolResultBatch = executeToolCalls(preparedContext, assistant_msg, toolCallList, config, 
                                           signal, eventSink)      
+        # eventSink("▶ _processMessage: tool batch")
         # save toolResults to messages
         for toolResult in toolResultBatch.messages
           push!(agentMsgHistory, toolResult)
         end
         if toolResultBatch.terminate
+          # eventSink("▶ _processMessage: TERMINATE branch")
           # If toolResultBatch requested termination, build a final response
           final_content = [textContent("Tool execution completed.")]
           for toolResult in toolResultBatch.messages
@@ -488,6 +500,7 @@ function _processMessage(
           break
         end
       else
+        # eventSink("▶ _processMessage: FINAL response")
         # LLM did not use tool calls — 
         break
       end
@@ -498,10 +511,12 @@ function _processMessage(
             println(io)
         end
 
-        eventSink(err_msg; publish=true)
+        # eventSink(err_msg; publish=true)
+        # eventSink("▶ _processMessage: CAUGHT ERROR")
     end
   end
 
+  # eventSink("▶ _processMessage: exited")
   return nothing
 end
 
@@ -611,9 +626,12 @@ The message is constructed from:
   1)  llm_useTool = JSON.Object{String, Any}("finish_reason" => "tool_calls", "index" => 0, "message" => JSON.Object{String, Any}("role" => "assistant", "content" => "", "reasoning_content" => "Here's a thinking process:\n\n1.  **Identify User Request**: The user is asking for the weather in Bangkok.\n2.  **Locate Relevant Tool**: I have a `getWeather` function available.\n3.  **Check Function Parameters**:\n   - `city` (required): City and country, e.g., 'San Francisco, CA' or 'Tokyo, Japan'\n   - `units` (optional, default \"celsius\"): Temperature scale (\"celsius\" or \"fahrenheit\")\n4.  **Prepare Parameters**:\n   - `city`: \"Bangkok, Thailand\" (adding country for clarity, though just \"Bangkok\" might work, following the example format is safer)\n   - `units`: Not specified, so I'll use the default (\"celsius\")\n5.  **Execute Tool Call**: Call `getWeather` with `city: \"Bangkok, Thailand\"`\n6.  **Anticipate Response**: The function will return current weather and forecast data for Bangkok. I'll then format it nicely for the user.\n   - *Self-Correction/Verification during thought*: The prompt says \"city: City and country, e.g., 'San Francisco, CA' or 'Tokyo, Japan'\". I'll use \"Bangkok, Thailand\". The `units` parameter is optional, so I'll omit it to use the default.\n   - Proceed with tool call.✅\n", "tool_calls" => Any[JSON.Object{String, Any}("type" => "function", "function" => JSON.Object{String, Any}("name" => "getWeather", "arguments" => "{\"city\":\"Bangkok, Thailand\"}"), "id" => "6fOilR5QPcdppbAAHluhkRyUDu3oWMAL")]))
   2)  llm_notUseTool = JSON.Object{String, Any}("finish_reason" => "stop", "index" => 0, "message" => JSON.Object{String, Any}("role" => "assistant", "content" => "The weather in London, UK is currently Sunny with a temperature of 22°C.", "reasoning_content" => "The user asked for the weather in London.\nI called the `getWeather` tool for London, UK.\nThe response indicates it's Sunny and 22°C.\nI will convey this information to the user.\n"))
 """
-function _extractToolCalls(response)
+function _extractToolCalls(response, eventSink=nothing)
     hasToolCalls = false
     toolCallList = agentToolCall[]
+    # if eventSink !== nothing
+    #     eventSink("▶ _extractToolCalls: parsing response")
+    # end
 
     # Helper: parse args (JSON string -> Dict, or pass through)
     parse_args(raw) = raw isa AbstractDict && !(raw isa Dict{String,Any}) ? 
@@ -943,9 +961,11 @@ function prepareToolCall(
 )::Union{preparedToolCall,immediateOutcome}
 
   # pick a called tool from tool store
+  # eventSink("▶ prepareToolCall: resolving")
   tool = get(context.tools, toolCall.name, nothing) 
   
   if tool === nothing
+    # eventSink("▶ prepareToolCall: NOT FOUND")
     return immediateOutcome(createErrorToolResult("Tool $toolCall.name not found"), true)
   end
 
@@ -953,6 +973,7 @@ function prepareToolCall(
     # 1. prepare arguments (tool-specific transform)
     prepared = prepareToolCallArguments(tool, toolCall)
     validatedArgs = validateToolArguments(tool, prepared)
+    eventSink("▶ prepareToolCall: validated")
     # 2. beforeToolCall hook — can block
     if config.beforeToolCall !== nothing
 
@@ -1032,8 +1053,10 @@ function executePreparedToolCall(
     eventSink,
   )::executedOutcome
 
+  # eventSink("▶ execute: START")
   try
     result = prep.tool.execute(prep.toolCall.id, prep.args, signal, eventSink)
+    # eventSink("▶ execute: END")
     return executedOutcome(result, false)
   catch e
     bt = catch_backtrace()
@@ -1041,7 +1064,8 @@ function executePreparedToolCall(
         showerror(io, e, bt)
         println(io)
     end
-    eventSink(errMsg; publish=true)
+    # eventSink(errMsg; publish=true)
+    # eventSink("▶ execute: ERROR")
 
     return executedOutcome(createErrorToolResult(sprint(showerror, e)), true)
   end
@@ -1115,6 +1139,7 @@ function finalizeExecutedToolCall(
     eventSink
 )::finalizedOutcome
 
+  # eventSink("▶ finalize: START")
   result = executed.result
   isError = executed.isError
   if config.afterToolCall !== nothing
@@ -1140,6 +1165,7 @@ function finalizeExecutedToolCall(
       isError = true
     end
   end
+  # eventSink("▶ finalize: END")
   return finalizedOutcome(prep.toolCall, result, isError)
 end
 
@@ -1207,6 +1233,7 @@ function executeToolCallsSequential(
 )::agentToolCallBatch
   finalizedCalls = finalizedOutcome[]
   messages = toolResultMessage[]
+  # eventSink("▶ executeToolCallsSequential: batch start")
 
   for tc in toolCalls
     prep = prepareToolCall(context, assistantMsg, tc, config, signal, eventSink)
@@ -1224,6 +1251,7 @@ function executeToolCallsSequential(
         break
     end
   end
+  # eventSink("▶ executeToolCallsSequential: batch end")
   return agentToolCallBatch(messages, shouldTerminate(finalizedCalls))
 end
 
@@ -1294,6 +1322,7 @@ function executeToolCallsParallel(
 )::agentToolCallBatch
 
   entries = Union{finalizedOutcome,Task}[]
+  # eventSink("▶ executeToolCallsParallel: batch start")
 
   for tc in toolCalls
     toolExecStartEvent(tc.id, tc.name, tc.arguments)
@@ -1333,6 +1362,7 @@ function executeToolCallsParallel(
       push!(messages, createToolResultMessage(f))
   end
 
+  # eventSink("▶ executeToolCallsParallel: batch end")
   return agentToolCallBatch(messages, shouldTerminate(finalizedCalls))
 end
 
@@ -1403,6 +1433,7 @@ function executeToolCalls(
           break
       end
   end
+  # eventSink("▶ executeToolCalls: dispatch")
   if config.toolExecution == "sequential" || hasSequential
     return executeToolCallsSequential(context, assistantMsg, toolCalls, config, signal,
                                       eventSink)
@@ -1447,8 +1478,11 @@ OpenAiToUserMessage(msg)
 # => userMessage("user", [textContent("Hello")], DateTime(...))
 ```
 """
-function OpenAiToUserMessage(msg::AbstractDict)::userMessage
+function OpenAiToUserMessage(msg::AbstractDict, eventSink=nothing)::userMessage
     content_blocks = Vector{messageContent}()
+    # if eventSink !== nothing
+    #     eventSink("▶ OpenAiToUserMessage: parsing")
+    # end
 
     raw_content = get(msg, "content", Any[])
     if raw_content isa Vector
@@ -1472,6 +1506,9 @@ function OpenAiToUserMessage(msg::AbstractDict)::userMessage
         end
     end
 
+    # if eventSink !== nothing
+    #     eventSink("▶ OpenAiToUserMessage: done")
+    # end
     return userMessage(content=content_blocks)
 end