require a key press before entering the dev console

this improves our ability to detect terminals that support line editing

src/tangara/dev_console/console.cpp

@@ -74,13 +74,29 @@ auto Console::RegisterCommonComponents() -> void {
   RegisterLogLevel();
 }
 
+static Console* sInstance;
+
+static auto prerun_cb() -> void {
+  if (sInstance) {
+    sInstance->PrerunCallback();
+  }
+}
+
+auto Console::PrerunCallback() -> void {
+  puts("\r\nPress any key to enter dev console.\r\n");
+  setvbuf(stdin, NULL, _IONBF, 0);
+  fgetc(stdin);
+}
+
 auto Console::Launch() -> void {
+  sInstance = this;
   esp_console_repl_t* repl = nullptr;
   esp_console_repl_config_t repl_config = ESP_CONSOLE_REPL_CONFIG_DEFAULT();
   repl_config.max_history_len = 16;
   repl_config.prompt = " →";
   repl_config.max_cmdline_length = 256;
   repl_config.task_stack_size = 1024 * GetStackSizeKiB();
+  repl_config.prerun_cb = prerun_cb;
 
   esp_console_dev_uart_config_t hw_config =
       ESP_CONSOLE_DEV_UART_CONFIG_DEFAULT();

src/tangara/dev_console/console.hpp

@@ -16,6 +16,7 @@ class Console {
   virtual ~Console();
 
   auto Launch() -> void;
+  virtual auto PrerunCallback() -> void;
 
  protected:
   virtual auto GetStackSizeKiB() -> uint16_t { return 8; }

src/tangara/system_fsm/booting.cpp

@@ -115,9 +115,11 @@ auto Booting::entry() -> void {
 
 auto Booting::exit() -> void {
   // TODO(jacqueline): Gate this on something. Debug flag? Flashing mode?
-  sAppConsole = new console::AppConsole();
+  sServices->bg_worker().Dispatch<void>([&] {
-  sAppConsole->sServices = sServices;
+    sAppConsole = new console::AppConsole();
-  sAppConsole->Launch();
+    sAppConsole->sServices = sServices;
+    sAppConsole->Launch();
+  });
 
   TimerHandle_t timer = xTimerCreate("INTERRUPTS", kInterruptCheckPeriod, true,
                                      NULL, check_interrupts_cb);

test/main/main.cpp

@@ -5,9 +5,13 @@
  */
 
 #include <stdio.h>
+#include <sys/fcntl.h>
+#include <sys/unistd.h>
 
 #include <cstdint>
 
+#include "freertos/FreeRTOS.h"
+
 #include "catch_runner.hpp"
 #include "esp_console.h"
 #include "esp_log.h"
@@ -27,6 +31,13 @@ void RegisterCatch2() {
 namespace console {
 
 class TestConsole : public Console {
+ public:
+  virtual auto PrerunCallback() -> void {
+    char* arg = "catch";
+    exec_catch2(1, &arg);
+    Console::PrerunCallback();
+  }
+
  protected:
   virtual auto RegisterExtraComponents() -> void { RegisterCatch2(); }
   virtual auto GetStackSizeKiB() -> uint16_t {