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, 7 insertions, 6 deletions

diff --git a/docs/fs.md b/docs/fs.md
index 83906d0a..7b1e47bf 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -518,12 +518,13 @@ A write of command lines -- to `look`, `exec`, `tagexec`, a `ctl` of the
 root, a pane or a column, or a column's `exec` -- runs each line once it is
 whole: a mount cuts a big write at its message size (4 KiB through the
 kernel's, 8 KiB from a client that asks), anywhere, and each piece comes as
-a write of its own, so the open keeps a last line with no newline yet, or
-an Edit block whose text has not ended, until its next write, and runs it
-then; what is left when it closes runs at the close -- so a line written
-with no newline (`printf Save > exec`) runs only as the file closes, after
-the write has been answered, and its failure is in the log alone: end each
-line with its newline to have the write itself fail -- where an Edit block
+a write of its own. A write that fills its piece may go on in the next, so
+the open keeps its last line with no newline until then; a write shorter
+than a piece is the whole of what was written, as acme takes each write, so
+its last line runs with it even with no newline (`printf Save > exec`), and
+a failure is that write's. Only what needs more is held: an Edit block
+whose `{` or `a`/`c`/`i` text has not ended waits for its next write, and
+what is left when the file closes runs at the close -- where an Edit block
 whose `{` or `a`/`c`/`i` text never ended fails and changes nothing
 (``unmatched `{'``, or `a, c or i text not ended by a . line`, logged as an
 `err`): sam takes the end of input for a `.`, but a block that reaches Edit