A 9P look keeps its leading blanks: an indented line, or blanks alone, is looked for as written

Every line written to look or exec went through Messages.next, which
trimmed blanks from both ends. A look of `    indented` then found the
first bare `indented`, and a diff's blank context line ` ` looked at
nothing. A look's line is now its text: only its `\r` and newline go.
lookAt keeps the blanks for the word search too; it expands `~` only for
a look that starts with one, and the path, address and command readings
trim for themselves as before. runSearch keeps a pattern's blanks, since
a builtin's argument comes trimmed already. An exec line is trimmed as
before. fs.md says so.

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 985e36a1..020fce58 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -196,7 +196,10 @@ an edit land. Modes are 0644/0666, 0444 read-only, 0222 write-only.
 
 ## look and exec
 
-A line written to `look` is a right click on it:
+A line written to `look` is a right click on it, on the line as written:
+its leading blanks are its own (`    return x` finds that indented line, and
+a diff's blank context line ` ` is a look too); only its newline and `\r`
+go. An `exec` line's blanks at either end are trimmed.
 
 - a path opens the file (the pane already showing it, if any); `file:12`
   selects line 12, newline included; `file:12:5` puts the caret at line 12,