working on todo.md features

src/help/02-source.txt

@@ -6,8 +6,19 @@ interface. Pass it on the command line, or let udpscope ask.
 <b>How to reach it</b>
 
 Run with <tt>--server</tt> and the app connects straight away. Run <i>without</i>
-<tt>--server</tt> and a chooser appears first: the sessions udpscope has stored, newest
-first, plus a <b>New host…</b> form for one it has not seen. The chooser runs before any
+<tt>--server</tt> and a chooser appears first: one row per stored <i>configuration</i>
+(<tt>host:port · name</tt>, its note, and the settings it carries), newest first, plus a
+<b>New host…</b> form that takes the address <i>and</i> the configuration it belongs to — its name
+and note, the <b>buffer size</b>, and whether time is relative or absolute. A row's pencil button
+opens the same form on that configuration, pre-filled, and changes to its name or address move it
+(the old file is deleted).
+
+The second page, <b>Waveforms</b>, opens an <i>exported</i> run instead of a live source: the files
+opened before (newest first; one that has since been deleted is marked <i>missing</i>) and an
+<b>Open…</b> button for a new one. The same file can be opened straight from the command line with
+<tt>--open FILE</tt>. A waveform is a source that never arrives — no socket, no acquisition, no
+starvation notice — and every instrument works on it: cursors, measurements, math channels and
+another export. Only <tt>.npy</tt> files are read. form for one it has not seen. The chooser runs before any
 buffer is allocated and before any socket is opened, so declining it costs nothing.
 
 <b>Worth knowing</b>