A name written with a blank at either end is refused, not quietly trimmed

`name` trimmed blanks off both ends, so `trailing.zig ` named another
file than the one written without a word. acme refuses any blank in a
name, `bad character in file name` (xfid.c:650); pardes takes one inside
(it names files with spaces) and now refuses one at an end, and a
control character, in acme's words.

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

1 files changed, 4 insertions, 1 deletions

diff --git a/docs/fs.md b/docs/fs.md
index 36fc7d7a..8e70af3e 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -496,7 +496,10 @@ selection, and leaves `look` reading back empty.
 
 `/pane/<n>/name` reads the pane's file name (a terminal's directory) and
 writing it renames the buffer; a relative name resolves against the pane's
-directory. `body` appends on write and replaces on truncating open. A
+directory. The write is the name and its newline, nothing trimmed: a blank
+inside a name is taken (`two words.zig`), but one at either end, or a
+control character, is refused, `bad character in file name` (EINVAL), as
+acme refuses a blank (xfid.c:650), rather than quietly cut off. `body` appends on write and replaces on truncating open. A
 terminal's `body` is its history as plain text, frozen per open, in logical
 lines: a row the terminal wrapped is joined back to the row before it (the
 wrap is ghostty's, as `pty/run`'s output unwraps), and the last line ends