A ctl line that ran and failed is not quoted after its reason; only one refused before running is

Failures of a builtin through a ctl quoted the line after the builtin's
own words, which already named it (`Mount dead /x: dial failed: no answer
"Mount dead /x"`), while the same failure through exec did not. A line
that ran says why in its own words everywhere now; only a line refused
as no message at all quotes it, as Plan 9's cmderror does.

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

1 files changed, 4 insertions, 2 deletions

diff --git a/docs/fs.md b/docs/fs.md
index 72789182..8f50a45b 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -270,8 +270,10 @@ all of them, `ThemeSel`'s list, are too many for an error);
 and `not a session control message "X": write it to pane/<n>/ctl` or `not
 a window control message "X": write it to /ctl` for a word of the other ctl. 9ns maps them all to EINVAL, and a write
 refused here has done nothing. A line that then fails as it runs fails the
-write with the error the editor reports for it and the line, e.g. `Mount:
-already mounted "Mount peer /tmp/s"` (EIO), and `control message needs its
+write with the error the editor reports for it, in its own words, which
+name what failed, the line not quoted after them (only a line refused
+before it runs, as no message at all, is quoted), e.g. `Mount: already
+mounted` (EIO), and `control message needs its
 argument "Save"` (EINVAL), for a builtin that would have asked at a prompt
 (a `Save` on a scratch) rather than open one nobody is there to answer. A
 builtin that means nothing without its argument (`Mount`, `Msg`, `Find`),