Only capture completions at the end of the buffer.

To prevent the suggestion from not starting with the buffer string.

Example:

`ls / /[cursor left][cursor left]b`

Before the patch, suggests `ls /b /ls /bin/ /`

After the patch, suggests `ls /b /bin/`.

https://github.com/zsh-users/zsh-autosuggestions/issues/343#issuecomment-401675712

src/strategies/completion.zsh

@@ -17,6 +17,9 @@ _zsh_autosuggest_capture_completion_widget() {
 	local -a +h comppostfuncs
 	comppostfuncs=(_zsh_autosuggest_capture_postcompletion)
 
+	# Only capture completions at the end of the buffer
+	CURSOR=$#BUFFER
+
 	# Run the original widget wrapping `.complete-word` so we don't
 	# recursively try to fetch suggestions, since our pty is forked
 	# after autosuggestions is initialized.

zsh-autosuggestions.zsh

@@ -487,6 +487,9 @@ _zsh_autosuggest_capture_completion_widget() {
 	local -a +h comppostfuncs
 	comppostfuncs=(_zsh_autosuggest_capture_postcompletion)
 
+	# Only capture completions at the end of the buffer
+	CURSOR=$#BUFFER
+
 	# Run the original widget wrapping `.complete-word` so we don't
 	# recursively try to fetch suggestions, since our pty is forked
 	# after autosuggestions is initialized.