A ctl or exec line with no newline runs with its write and fails it, unless it needs more

A last line with no newline was held to the close, so printf bogus > ctl answered 0 and failed only in the log, Edit ,s/zzz/y/ too. A write shorter than its Twrite is the whole of what was written (acme takes each write whole): its tail runs then and a failure is the write's. It is held only when the parser says it needs more -- an open { block, an a/c/i text -- or when the write filled its Twrite and may go on (the listener tells the core the room, msize less its header).

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

1 files changed, 4 insertions, 3 deletions

diff --git a/.agents/skills/pardes-9p/SKILL.md b/.agents/skills/pardes-9p/SKILL.md
index 16e90dc9..0de8820a 100644
--- a/.agents/skills/pardes-9p/SKILL.md
+++ b/.agents/skills/pardes-9p/SKILL.md
@@ -164,9 +164,10 @@ an open that never wrote, the session's last. With other clients about,
 write and read one open (`exec 3<>$m/look; echo x >&3; cat <&3; exec 3<&-`).
 A read is a stream: once read, a second read on the same fd gives EOF (on
 an open that wrote, until its next write); open again, or seek to 0, to read
-it again. Each command line runs once whole, however a mount cuts a big write; a last
-line with no newline runs when the open closes, and an Edit block still open
-then fails there (an `err`: ``unmatched `{'``, or an a/c/i text with no `.`
+it again. Each command line runs once whole, however a mount cuts a big write; a
+write's last line with no newline runs with it (and fails it), unless the
+write filled its 9P message and may go on; an Edit block still open when the
+file closes fails there (an `err`: ``unmatched `{'``, or an a/c/i text with no `.`
 line), changing nothing. One rule: a builtin that fails, whether through a
 ctl (a pane's pty/ctl `exec` too), look, exec, tagexec or a column's exec,
 fails the write (EINVAL for a malformed line, ENOENT for what is not there --