feat(ssa): Agent channel UX optimization (Solution B) + Plan-and-Execute architecture design

SSA Agent channel improvements (12 code files, +931/-203 lines):
- Solution B: left/right separation of concerns (gaze guiding + state mutex + time-travel)
- JWT token refresh mechanism (ensureFreshToken) to fix HTTP 401 during pipeline
- Code truncation fix: LLM maxTokens 4000->8000 + CSS max-height 60vh
- Retry streaming code generation with generateCodeStream()
- R Docker structured errors: 20+ pattern matching + format_agent_error + line extraction
- Prompt iron rules: strict output format in CoderAgent System Prompt
- parseCode robustness: XML/Markdown/inference 3-tier matching + length validation
- consoleOutput type defense: handle both array and scalar from R Docker unboxedJSON
- Agent progress bar sync: derive phase from agentExecution.status
- Export report / view code buttons restored for Agent mode
- ExecutingProgress component: real-time timer + dynamic tips + step pulse animation

Architecture design (3 review reports):
- Plan-and-Execute step-by-step execution architecture approved
- Code accumulation strategy (R Docker stays stateless)
- 5 engineering guardrails: XML tags, AST pre-check, defensive prompts, high-fidelity schema, error classification circuit breaker

Docs: update SSA module status v4.1, system status v6.7, deployment changelist
Made-with: Cursor

r-statistics-service/plumber.R

@@ -192,28 +192,39 @@ function(req) {
     
     message(glue::glue("[ExecuteCode] session={session_id}, code_length={nchar(code)}, timeout={timeout_sec}s"))
     
-    # 在隔离环境中执行，预加载 block_helpers 和 data_loader
     sandbox_env <- new.env(parent = globalenv())
     
-    # 如果有 session_id，尝试预设数据路径变量
     if (!is.null(session_id) && nchar(session_id) > 0) {
       sandbox_env$SESSION_ID <- session_id
     }
     
     start_time <- proc.time()
     
-    # 捕获输出和结果
+    collected_warnings <- list()
+    collected_messages <- character(0)
+    
     output_capture <- tryCatch(
       withTimeout(
         {
-          # 捕获打印输出
           captured_output <- utils::capture.output({
-            result <- eval(parse(text = code), envir = sandbox_env)
+            result <- withCallingHandlers(
+              eval(parse(text = code), envir = sandbox_env),
+              warning = function(w) {
+                collected_warnings[[length(collected_warnings) + 1]] <<- w$message
+                invokeRestart("muffleWarning")
+              },
+              message = function(m) {
+                collected_messages <<- c(collected_messages, conditionMessage(m))
+                invokeRestart("muffleMessage")
+              }
+            )
           })
           
           list(
             result = result,
             output = captured_output,
+            warnings = collected_warnings,
+            messages = collected_messages,
             error = NULL
           )
         },
@@ -221,10 +232,14 @@ function(req) {
         onTimeout = "error"
       ),
       error = function(e) {
+        error_info <- format_agent_error(e, code, collected_warnings, collected_messages)
         list(
           result = NULL,
           output = NULL,
-          error = e$message
+          warnings = collected_warnings,
+          messages = collected_messages,
+          error = error_info$message,
+          error_detail = error_info
         )
       }
     )
@@ -232,39 +247,54 @@ function(req) {
     elapsed_ms <- round((proc.time() - start_time)["elapsed"] * 1000)
     
     if (!is.null(output_capture$error)) {
+      detail <- output_capture$error_detail
       message(glue::glue("[ExecuteCode] ERROR after {elapsed_ms}ms: {output_capture$error}"))
+      
+      console_lines <- c(
+        output_capture$output,
+        if (length(output_capture$warnings) > 0) paste0("Warning: ", output_capture$warnings),
+        if (length(output_capture$messages) > 0) output_capture$messages
+      )
+      
       return(list(
         status = "error",
-        error_code = "E_EXEC",
+        error_code = if (!is.null(detail)) detail$error_code else "E_EXEC",
+        error_type = if (!is.null(detail)) detail$error_type else "runtime",
         message = output_capture$error,
-        user_hint = paste0("R 代码执行出错 (", elapsed_ms, "ms): ", output_capture$error),
+        user_hint = if (!is.null(detail)) detail$user_hint else output_capture$error,
+        error_line = if (!is.null(detail)) detail$error_line else NULL,
+        error_context = if (!is.null(detail)) detail$error_context else NULL,
+        console_output = console_lines,
         duration_ms = elapsed_ms
       ))
     }
     
     message(glue::glue("[ExecuteCode] SUCCESS in {elapsed_ms}ms"))
     
-    # 将结果标准化
     final_result <- output_capture$result
     
-    # 如果结果是 list 且包含 report_blocks，直接返回
+    console_lines <- c(
+      output_capture$output,
+      if (length(output_capture$warnings) > 0) paste0("Warning: ", output_capture$warnings),
+      if (length(output_capture$messages) > 0) output_capture$messages
+    )
+    
     if (is.list(final_result) && !is.null(final_result$report_blocks)) {
       return(list(
         status = "success",
         result = final_result,
-        console_output = output_capture$output,
+        console_output = console_lines,
         duration_ms = elapsed_ms
       ))
     }
     
-    # 否则包装为通用结果
     return(list(
       status = "success",
       result = list(
         data = final_result,
         report_blocks = list()
       ),
-      console_output = output_capture$output,
+      console_output = console_lines,
       duration_ms = elapsed_ms
     ))