I can use

print -S "echo test"

to place the command echo test into the history file, so that when I hit the UP-arrow, I get it into the zle buffer.

This does not seem to work from within a zsh startup file. For instance, I put at the last command in my .zshrc the line

print -S ": testing"

and started a subshell using

zsh

I would expect that, when I press now the up-arrow, I would get the command : testing for execution, but instead I get the most recently, manually entered command.

My history is configured like this:

HISTFILE=~/.histfile.$TTY:t
HISTSIZE=500
SAVEHIST=$HISTSIZE
setopt hist_ignore_all_dups
setopt hist_ignore_space
setopt hist_no_store 
setopt hist_reduce_blanks
setopt incappendhistory
setopt no_share_history

I have ensured that my .zshrc has indeed been sourced when I typed zsh (i.e. the variable ZDOTDIR is not set), so the print -S must have been executed.

My guess is that during sourcing of .zshrc, the history mechanism itself has not been set up yet, and therefore the print -S does not take effect.

I was thinking to put the logic into the precmd hook (and ensure that the command is only placed into the history the very first time the precmd is executed), but I wonder if there is a simpler way to implement this.