A command line cut across writes runs once whole, and look/exec answer per open

A mount cuts a write at its message size, and each piece ran on its own: a
line cut at the boundary ran as shell commands and a 50 KB Edit block
broke. An open of look, exec, tagexec, any ctl or a column's exec now keeps
an unfinished last line, or an Edit block still open, until its next write
or its release, and never runs a fragment. The same open record holds what
its last write touched, which a read on it answers (as /net/tcp/clone
does); an open that never wrote reads the session's last as of its open.
A release that runs a held line waits for quiet and counts as a change;
a clicked line with a control character is still refused at its write.
Tested in unit tests, fs.py (python client, 8 KiB) and selfmount.py (the
kernel mount, a 1000-line seq burst and a 50 KB Edit block).

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

1 files changed, 2 insertions, 2 deletions

diff --git a/src/fs-help.txt b/src/fs-help.txt
index 3d84fca2..5a3be01b 100644
--- a/src/fs-help.txt
+++ b/src/fs-help.txt
@@ -3,7 +3,7 @@ Pardes control filesystem
 README      this guide
 index       one line per pane: serial, kind (text|term|pdf|image), dirty flag, name (+New if unnamed), column serial
 status      pid, version and pane count
-look        write a line: a right click on it at the active pane; read: the serials it touched
+look        write a line: a right click on it at the active pane; read: the serials it touched (this open's)
 exec        write a line: a middle click, an editor command word or a shell line; read the same (every exec file)
 log         events: new del rename save newcol delcol run exit send ask answer dump restore restored restoredcol msg err
 screen      rendered screen as JSON, frozen from open to close
@@ -39,7 +39,7 @@ Pitfalls, one each:
   data: > replaces the addr range, : > deletes it, a 2nd > inserts (addr moved); body: > empties all.
   tag reads the path, then its own text; > replaces that text (default words too), >> appends.
   A terminal's body is a history snapshot frozen per open, wrapped rows joined into lines; pty/data is the live stream.
-  exec: a non-builtin line runs as a command pane (ctl's Shell -c; exit N shown, logged), a shell's typed in.
+  exec: a non-builtin line runs as a command pane (ctl's Shell -c), a shell's typed in; a line runs once whole.
   Through a mount a malformed write is EINVAL, a failed one EIO or an errno that fits (ENOENT): log's err says why.
   lock/unlock need a held ctl fd (exec 3>ctl); a held lock fails: retry. fs.md has the rest.
   Repl python on a terminal's ctl: a .py body's clicks go to it (Repl - unbinds, Repl says it); tags stay commands.