A terminal keeps its tag and two body rows through drags, squeezes and a smaller window

A terminal of one body row loses its prompt's mark and reads busy for
ever. Placement already refused to make one that short; now layout never
leaves one there either: a grip drag stops at the floor, and a column
squeezed by weights or by the window takes the rows from its other panes.
Text panes keep acme's way and can still be dragged to their tag, since
acme has no terminals to follow. The shrinktag, splitparent and cornerdrag
goldens are re-recorded for it, shrinktag's re-grab moved to where the
grip now is.

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

1 files changed, 9 insertions, 0 deletions

diff --git a/docs/tags.md b/docs/tags.md
index 3db7f465..46c2defa 100644
--- a/docs/tags.md
+++ b/docs/tags.md
@@ -248,6 +248,15 @@ that room, the column's tallest pane is halved instead; where no pane of the
 column can give it, the new pane is refused and closed, with `no space for a
 pane in that column: each keeps its tag and 2 rows` (a 9P write or open of
 `pane/new` fails with it, ENOSPC). A pane alone in its column always fits.
+
+After placement a terminal keeps that floor too: no drag of a grip, no
+squeeze of its column by the others' weights and no smaller window takes
+it below its tag and two body rows (a one-row terminal loses its prompt's
+mark and would read busy for ever); its neighbours give the rows, and only
+a window too short for every floor leaves it less. A text pane keeps
+acme's way and can be dragged down to its tag alone; acme has no
+terminals to follow here. A folded terminal (Collapse) is a tag by choice.
+`pty/ctl`'s `winsize` likewise gives a pty two rows at least.
 A `+Errors` pane goes to any column with room, the last first; with none,
 what it would have shown (an Edit's `p` or `=`, a write to `errors`) is
 logged as `msg` records, a line each, and the Edit still succeeds.