fix(zsh): move dotDir to XDG (~/.config/zsh), preserve history

Set programs.zsh.dotDir to ~/.config/zsh, adopting the new home-manager
default and silencing the dotDir deprecation warning on rebuild. Pin
history.path to the existing ~/.zsh_history so the move doesn't orphan it,
and extend the zcompdump-reset activation to the new $ZDOTDIR location
(legacy $HOME and cache paths still swept). README updated.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyrathorpe/home/README.md

@@ -22,12 +22,13 @@ on top (work email, its own ssh config, extra packages).
 ## zsh
 
 | Feature                  | Notes                                                                                                                                          |
-| ------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------ |
+| ------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------- |
 | oh-my-zsh                | plugins `git`, `man`, `sudo` (Esc-Esc to prepend sudo), `colored-man-pages`, `extract`; theme `robbyrussell`                                   |
 | Autosuggestion           | fish-style history suggestions as you type (→ to accept)                                                                                       |
 | Syntax highlighting      | commands coloured by validity as you type                                                                                                      |
 | Completion               | menu completion; the dump is rebuilt on every activation (see Maintenance)                                                                     |
-| History                  | 100k in-memory/on-disk, deduped, space-prefixed commands ignored, timestamped, **shared live across sessions**                             |
+| History                  | 100k in-memory/on-disk, deduped, space-prefixed commands ignored, timestamped, **shared live across sessions**; file stays at `~/.zsh_history` |
+| Dotfiles location        | `dotDir` is `~/.config/zsh` (XDG) — `.zshrc`/`.zshenv`/`.zcompdump` live there; `~/.zshenv` only bootstraps `$ZDOTDIR`                         |
 | History substring search | type a fragment, then ↑/↓ cycles matching past commands — works in foot, iTerm2 and the Linux TTY (both CSI and SS3 arrow encodings bound)     |
 | Prompt                   | hostname is prefixed when over SSH                                                                                                             |
 
@@ -128,7 +129,8 @@ forced off there) but still runs the agent.
 
 ## Maintenance behaviours
 
-- **zcompdump reset** — `~/.zcompdump*` is removed on every activation, so a stale
+- **zcompdump reset** — `~/.config/zsh/.zcompdump*` (plus legacy `~/.zcompdump*`
+  and the cache copy) is removed on every activation, so a stale
   dump (pointing at `/nix/store` paths a rebuild or a manual GC removed) can't
   break completion with `_git: function definition file not found`.
 - **GC** — no scheduled timer; collect garbage deliberately (`nh clean all` /

lyrathorpe/home/shell.nix

@@ -1,5 +1,6 @@
 # Interactive shell: zsh + tmux. Wanted on every host.
 {
+  config,
   lib,
   pkgs,
   inputs,
@@ -28,6 +29,10 @@ in
 
   programs.zsh = {
     enable = true;
+    # Keep zsh dotfiles under XDG (~/.config/zsh) rather than the legacy $HOME
+    # layout, matching xdg.enable. history.path is pinned below so the existing
+    # ~/.zsh_history is reused, not orphaned by the dotDir move.
+    dotDir = "${config.xdg.configHome}/zsh";
     enableCompletion = true;
     enableVteIntegration = true;
     autosuggestion.enable = true;
@@ -47,6 +52,9 @@ in
       ];
     };
     history = {
+      # Stay at the legacy ~/.zsh_history (default would follow dotDir into
+      # ~/.config/zsh and orphan the existing file). Keeps history intact.
+      path = "${config.home.homeDirectory}/.zsh_history";
       append = true; # append, don't overwrite, on shell exit
       size = 100000; # in-memory (HISTSIZE)
       save = 100000; # on-disk (SAVEHIST)
@@ -324,12 +332,16 @@ in
   # enables this in the work module; both being true merges cleanly.
   services.ssh-agent.enable = lib.mkIf pkgs.stdenv.hostPlatform.isLinux true;
 
-  # Drop the zsh completion dump on every activation. A stale ~/.zcompdump
-  # caches /nix/store paths to completion functions; once a rebuild or a manual
-  # GC removes them, compinit fails with "_git: function definition file not
-  # found" for every completion. Deleting it forces a fresh rebuild from the
-  # current fpath on the next shell.
+  # Drop the zsh completion dump on every activation. A stale .zcompdump caches
+  # /nix/store paths to completion functions; once a rebuild or a manual GC
+  # removes them, compinit fails with "_git: function definition file not found"
+  # for every completion. Deleting it forces a fresh rebuild from the current
+  # fpath on the next shell. compinit dumps to $ZDOTDIR (~/.config/zsh now); the
+  # $HOME and cache paths are also swept to clear any legacy leftovers.
   home.activation.resetZcompdump = lib.hm.dag.entryAfter [ "writeBoundary" ] ''
-    $DRY_RUN_CMD rm -f "$HOME"/.zcompdump* "''${XDG_CACHE_HOME:-$HOME/.cache}"/zsh/.zcompdump* 2>/dev/null || true
+    $DRY_RUN_CMD rm -f \
+      "${config.xdg.configHome}"/zsh/.zcompdump* \
+      "$HOME"/.zcompdump* \
+      "''${XDG_CACHE_HOME:-$HOME/.cache}"/zsh/.zcompdump* 2>/dev/null || true
   '';
 }