working on todo.md features

src/config.hpp

@@ -24,6 +24,10 @@ struct Config {
   /// Size of *each* of the two sample buffers, in megabytes. The application
   /// always allocates two identical buffers (spec item 1).
   double buffer_mb = 200.0;
+  /// Whether `--buffer-mb` was given. A stored configuration's buffer size fills in only when the
+  /// flag was *absent*: an explicit flag beats a saved setting, and "not asked" is not the same
+  /// question as "asked for 200".
+  bool buffer_mb_specified = false;
 
   /// Largest time window the toolbar offers, in seconds. The buffer partition is
   /// sized to hold at least this much time (spec: decimation).
@@ -40,6 +44,16 @@ struct Config {
   /// from the stream's own time signal, so arrival and producer-clock jitter cannot move a
   /// sample's x. Absolute stream time is still recorded, for export only (`todo.md` item 2).
   bool relative_time = false;
+
+  /// `--capture-packets N`: the ring size of the raw-datagram capture, 1..100000.
+  /// 0 means the flag was absent: the capture is off, and the popover button then
+  /// uses the 1000-slot default when the user toggles it.
+  std::uint32_t capture_packets = 0;
+
+  /// `--open FILE`: a `.npy` an earlier run exported, opened for viewing and analysis instead of a
+  /// live source. File mode and source mode are exclusive -- there is no acquisition behind a file,
+  /// and the chooser's Waveforms page sets this rather than the connection fields.
+  std::string open_waveform;
 };
 
 /// Parses argv. On `--help` prints usage to stdout and exits(0); on a bad