The docs: the root exec's lines are the active pane's in the log, a tag's are `-`

fs.md said a root exec logged `-` while the keyboard was on a tag; it
runs at the active pane and logs that pane's serial all the same. The `-`
is for /tagexec, a column's exec and ctl, and the root's ctl.

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

1 files changed, 5 insertions, 3 deletions

diff --git a/docs/fs.md b/docs/fs.md
index 9adef635..84b27b1f 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -763,9 +763,11 @@ open of `pane/new`) is logged by that write's `err` alone, no announcement
 and no `msg`, so the same failure again is the same record again; a line said again word for word is counted, `msg 3 Undo: nothing to
 undo (x40)`, as `err` is (below); a text past 256 bytes is cut there,
 between words, and ends in an ellipsis, `…`, as an `err`'s reason is past
-200; its serial is the pane it ran at, `-` when the keyboard was on a
-column or workspace tag, or the line came to the root's ctl, `/tagexec` or
-a column's ctl or exec), and `err <serial|->
+200; its serial is the pane it ran at -- a line written to the root's
+`exec` or `look` runs at the active pane, and is logged as that pane's,
+even while the keyboard is on a column's or the workspace's tag -- and `-`
+for a line to the root's `ctl`, `/tagexec`, or a column's `ctl` or `exec`,
+which run in a tag no pane owns), and `err <serial|->
 <file>: <why>` (the serial is that of the pane whose file it is, and for
 the root's `exec` and `look` the pane the line ran at, `err 3 exec: ...`;
 `-` for another root file) for every write or truncation the tree refused or that