An a, c or i text with no . line fails the Edit, as an open { does

sam takes the end of input as a text block's end, so a block cut short (a
write that lost its tail, an open closed early) inserted half of itself.
An Edit whose a, c or i text never meets its . line now fails with "a, c
or i text not ended by a . line" and changes nothing, as an unclosed {
does; at a close, logged as an err.

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 62716cf0..f61bbbe6 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -429,8 +429,10 @@ 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, where an Edit block
-whose `{` or text never ended fails as any unclosed block does (``unmatched
-`{'``, logged as an `err`; nothing changes). A fragment never runs on its
+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
+unfinished was cut short. A fragment never runs on its
 own. A line or Edit block held past 1 MiB is refused (EINVAL).
 
 A look takes acme's addresses after a colon (editors/acme/look.c:450): a