Record /log whether or not anyone reads it, with the editor's messages in it

/log is now one ring (64 KiB, 4 KiB on the board) that records new, del,
rename and save, and a msg line for everything the editor says. An open
freezes it, so cat log shows what happened lately and ends; writing
follow to that same open makes reads past it wait for newer records, and
a follower the ring outran reads lost N first.

The message log keeps the pane's serial, not its reusable slot.

A test now fails when the tree serves a file /README never mentions; it
caught pty/status, now documented along with typing through pty/data.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 5 insertions, 4 deletions

diff --git a/src/fs-help.txt b/src/fs-help.txt
index 7f55b3af..dca2c14e 100644
--- a/src/fs-help.txt
+++ b/src/fs-help.txt
@@ -5,7 +5,8 @@ index       one line per pane: serial, kind (text|term|pdf|image), dirty flag, n
 status      pid, version and pane count
 look        write a line: a right click on it at the active pane; read: the serials it touched
 exec        write a line: a middle click, an editor command word or a shell line; read the same
-log         one line per editor event (new/del/rename/save <serial> <name>); reads wait
+log         recent events, one a line: new/del/rename/save <serial> <name>, and
+            msg <serial|-> <text> for what the editor said; write follow to wait
 screen      rendered screen as JSON, frozen from open to close
 listeners   the session's dial addresses
 pane/new    open it to make a pane; the read answers that pane's serial
@@ -26,9 +27,10 @@ Below, $m is the mount point (PARDES_MOUNT in a Tty9p shell; 9ns and 9p work too
   echo '#0,#5' > $m/pane/$n/addr; printf NEW >> $m/pane/$n/data  replace bytes 0..5
   cp $m/pane/$n/addr $m/pane/$n/dot; cat $m/pane/$n/sel   select the range, read it
   cat $m/pane/$n/dirty; echo 0 > $m/pane/$n/dirty         is it modified? say it is not
-  cat $m/log                                   block until a pane is made, renamed, saved or closed
+  exec 3<>$m/log; echo follow >&3; cat <&3     what happened lately, then wait for more
   cat $m/pane/$n/event                         hold it open to own that pane's clicks
   echo exec > $m/pane/$n/pty/ctl               restart a shell; also winsize C R, sig INT
+  printf 'ls\r' > $m/pane/$n/pty/data           type into a terminal; pty/status: cols rows busy
 
 Pitfalls, one each:
   Each open of pane/new makes another pane; two reads of one fid name the same one.
@@ -39,6 +41,5 @@ Pitfalls, one each:
   Writing body appends; open it with truncation to replace; writes are whole UTF-8 sequences.
   Truncating tag clears the part you may edit; truncating dot or addr empties it.
   A terminal's body is a history snapshot frozen per open; pty/data is the live stream.
-  screen is frozen per open handle as well; reopen it for a fresh frame.
-  A failing command is reported in the editor, not as a write error; a bad line fails the write.
+  A failing command is reported in the editor and in log, not as a write error; a bad line fails the write.
   pane/<n>/ctl reads acme's window status line and takes one verb, get, which reloads from disk.