fix(shell): bind arrows directly for bash history search

The macro form `"\e[A": "\C-x\C-p\C-e"` ran history-search-backward then
end-of-line to mimic zsh's cursor-at-end. But history-search-* takes its
prefix from start-of-line to point, and `\C-e` moves point to the end, so
the next Up searched for the whole recalled line, found nothing, and left
Up/Down dead after one press. Bind arrows straight to the search functions;
pure readline has no history-search-end widget, so cursor lands at the
prefix boundary.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -0,0 +1,23 @@
+# dotfiles
+
+Designed around [GNU stow][gnu stow manual].
+For `zsh` or `bash` (or both). Include `shell/` always.
+
+## Install
+
+```sh
+git clone <repo> ~/.dotfiles
+cd ~/.dotfiles
+stow shell zsh # or: stow shell bash
+```
+
+## Update
+
+```sh
+cd ~/.dotfiles
+git pull
+stow -R shell zsh # restow this host's packages
+```
+
+[gnu stow manual]: https://www.gnu.org/software/stow/manual/stow.html
+

bash/.config/bash/rc

@@ -10,7 +10,8 @@
 # Case-insensitive globbing (used in pathname expansion)
 shopt -s nocaseglob;
 
-# Append to the Bash history file, rather than overwriting it
+# Append to the Bash history file, rather than overwriting it.
+# (HISTFILE/HISTSIZE/HISTFILESIZE/HISTCONTROL come from ~/.config/shell/exports.)
 shopt -s histappend;
 
 # Autocorrect typos in path names when using `cd`

shell/.config/readline/inputrc

@@ -0,0 +1,20 @@
+# Readline config (bash line editing + any readline program: python, psql...).
+# Set via $INPUTRC; see shell/exports. zsh ignores this (uses ZLE); its
+# equivalent prefix-search bindings live in zsh/.zshrc.
+#
+# Pull in distro defaults; a custom INPUTRC otherwise replaces them entirely.
+$include /etc/inputrc
+
+# zsh-style prefix history search: type a prefix, Up/Down walk matching
+# history entries. Empty prefix = previous/next.
+#
+# Bind arrows straight to the search functions. Do NOT wrap in a macro that
+# appends end-of-line (\C-e) to mimic zsh's cursor-at-end: \C-e moves point to
+# the line end, and history-search-* takes its prefix from start-of-line to
+# point -- so the next press searches for the whole recalled line, finds
+# nothing, and Up/Down go dead. Pure readline has no history-search-end widget;
+# cursor lands at the prefix boundary, which is readline's intended behavior.
+"\e[A": history-search-backward
+"\e[B": history-search-forward
+"\eOA": history-search-backward
+"\eOB": history-search-forward

shell/.config/shell/exports

@@ -7,8 +7,14 @@ export XDG_CACHE_HOME="$HOME/.cache"
 # Default editor
 export EDITOR='vim'
 
-# Shell history file
+# Shell history (env vars both shells read; each ignores the other's by name —
+# zsh uses SAVEHIST, bash uses HISTFILESIZE/HISTCONTROL. zsh dedup is a setopt,
+# not an env var, so it stays in .zshrc).
 export HISTFILE="${XDG_CACHE_HOME:-$HOME/.cache}/shell/history"
+export HISTSIZE=1000000        # commands kept in memory (both shells)
+export SAVEHIST=1000000        # zsh: lines written to $HISTFILE
+export HISTFILESIZE=1000000    # bash: lines written to $HISTFILE
+export HISTCONTROL=ignoreboth  # bash: drop dups + space-prefixed
 
 # Global git config file
 export GIT_CONFIG_GLOBAL="${XDG_CONFIG_HOME:-$HOME/.config}/git/config"
@@ -33,5 +39,8 @@ export PYTHON_HISTFILE="${XDG_CACHE_HOME:-$HOME/.cache}/python/history"
 # Wget config file
 export WGETRC="${XDG_CONFIG_HOME:-$HOME/.config}/wget/rc"
 
+# Readline config file (bash line editing + any readline program)
+export INPUTRC="${XDG_CONFIG_HOME:-$HOME/.config}/readline/inputrc"
+
 # NOTE: ZDOTDIR lives in ~/.zshenv, not here. It must be set before zsh reads
 # any rc file, and this file is sourced too late for that.

shell/.config/shell/interactive

@@ -8,5 +8,9 @@ for _file in "${XDG_CONFIG_HOME:-$HOME/.config}"/shell/{aliases,functions,extra}
 done
 unset _file
 
+# Ensure the history dir exists; neither shell mkdir's it, so without this
+# $HISTFILE writes fail silently on a fresh host.
+[ -n "$HISTFILE" ] && mkdir -p "$(dirname "$HISTFILE")"
+
 # pyenv interactive shims (pyenv init - autodetects the running shell):
 command -v pyenv >/dev/null 2>&1 && eval "$(pyenv init -)"

zsh/.config/zsh/.zshrc

@@ -12,9 +12,9 @@ setopt autocd		# Automatically cd into typed directory.
 stty stop undef		# Disable ctrl-s to freeze terminal.
 setopt interactive_comments
 
-# History in cache directory:
-HISTSIZE=10000000
-SAVEHIST=10000000
+# HISTFILE/HISTSIZE/SAVEHIST come from ~/.config/shell/exports (shared).
+# Dedup is a setopt, not an env var (bash's HISTCONTROL=ignoreboth equivalent):
+setopt hist_ignore_all_dups hist_ignore_space
 
 # Basic auto/tab complete:
 autoload -U compinit