fix(tmux): do not configure a tmux that is not installed

AGENTS.md

@@ -58,6 +58,12 @@ fallback and the unapplied-pins path - 28 cells total.
   list with a per-package retry, keep an optional tool's apt steps non-fatal
   (`|| { log_warn ...; return; }`), and let the `_install_*` GitHub fallbacks
   cover whatever apt cannot supply.
+- **Do not configure what is not installed.** `install_zsh` and `install_tmux` both
+  return early with an actionable warning when their binary is absent; a host that
+  looks configured while nothing can use it is how the no-sudo tmux gap stayed
+  invisible. Guard EVERY entry point, not just the first: install.sh chains
+  `install_tmux && _install_tmux_plugins`, and the early return must exit 0 or
+  `set -e` kills the run - so the chained function needs its own guard.
 - **Never let a test environment supply the thing under test** (`tests/no-fixture-masking.py` enforces this for tools with an `_install_*` function; it cannot see a tool the repo ships config for but never installs, which is what the original gap was). The no-sudo CI jobs
   and `Dockerfile.nosudo` pre-installed tmux as a root prerequisite, so `has tmux`
   was true before install.sh ran. A non-sudoer therefore got tmux CONFIG and tmux

CHANGELOG.md

@@ -5,6 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.13.2] - 2026-09-19
+
+### Fixed
+- install.sh no longer links tmux config or clones tmux plugins when tmux is absent. It configured a tmux that was not there whenever the installer came up empty - a non-x86_64 host, a download failure, an AppImage that neither runs nor extracts - which is the incoherence that hid the original no-sudo gap. Matches how zsh is already handled.
+
 ## [1.13.1] - 2026-09-19
 
 ### Added

VERSION

@@ -1 +1 @@
-1.13.1
+1.13.2

modules/tmux.sh

@@ -10,6 +10,17 @@ _TMUX_PLUGINS=(
 )
 
 install_tmux() {
+    # Do not configure what is not there. Linking tmux config and cloning tmux
+    # plugins for an absent tmux is the incoherence that hid the no-sudo gap: a
+    # host looked configured while nothing could use it. _install_tmux covers the
+    # common cases now, but it still returns empty-handed on a non-x86_64 host, on
+    # a download failure, or when the AppImage neither runs nor extracts - so this
+    # guard is what makes the outcome honest. Same shape as install_zsh().
+    if ! has tmux; then
+        log_warn "tmux not found - skipping tmux config and plugins"
+        log_warn "  Install tmux, then re-run: bash ${DOTFILES_DIR}/install.sh"
+        return 0
+    fi
     log_step "tmux config"
     symlink "${DOTFILES_DIR}/tmux/.tmux.conf"       ~/.tmux.conf
     symlink "${DOTFILES_DIR}/tmux/.tmux.conf.local"  ~/.tmux.conf.local
@@ -20,6 +31,13 @@ install_tmux() {
 }
 
 _install_tmux_plugins() {
+    # Guarded separately, not just via install_tmux: install.sh chains them with
+    # `install_tmux && _install_tmux_plugins`, so install_tmux's early return - which
+    # must exit 0, or `set -e` would kill the whole install - still lets this run.
+    if ! has tmux; then
+        log_warn "tmux not found - skipping tmux plugins"
+        return 0
+    fi
     log_step "tmux plugins"
     local plugin_dir="$HOME/.tmux/plugins"
     mkdir -p "$plugin_dir"