feat(shell): restore zsh as default shell

- Switch nix-darwin and Home Manager shell wiring from fish to zsh
- Port zsh snippets and Codex helper commands from fish
- Update shell benchmark workflows and editor defaults for zsh

Co-authored-by: Codex GPT-5.5 <noreply@openai.com>

Author: lemtoc

.github/actions/run-benchmark/action.yml

@@ -1,5 +1,5 @@
 name: Run Benchmark
-description: Run fish startup benchmark with hyperfine and convert results
+description: Run zsh startup benchmark with hyperfine and convert results
 
 outputs:
   result-path:
@@ -16,7 +16,7 @@ runs:
           --warmup 10 \
           --runs 50 \
           --export-json bench-result.json \
-          'fish -i -c exit'
+          'zsh -i -c exit'
 
     - name: Convert to benchmark format
       shell: bash

.github/actions/setup-bench-env/action.yml

@@ -1,5 +1,5 @@
 name: Setup Benchmark Environment
-description: Install Nix, build home-manager generation, and set up fish shell environment for benchmarking
+description: Install Nix, build home-manager generation, and set up zsh shell environment for benchmarking
 
 outputs:
   hm_gen:
@@ -29,7 +29,7 @@ runs:
         # - /etc/zprofile: remove path_helper (slow PATH construction)
         # - /etc/zshrc: remove compinit/promptinit (nix-darwin sets enableGlobalCompInit=false)
         # - /etc/zshenv: keep Nix daemon setup for PATH
-        # See hosts/common/default.nix:19-23
+        # See hosts/common/default.nix for the matching nix-darwin zsh settings.
         sudo sh -c '
           echo "" > /etc/zprofile
           echo "" > /etc/zshrc
@@ -39,6 +39,11 @@ runs:
         sudo mkdir -p /Users/t1190078
         sudo chown "$(whoami)" /Users/t1190078
 
+        # Symlink user-level zsh dotfiles
+        ln -sf "$HM_GEN/home-files/.zshrc" ~/.zshrc
+        ln -sf "$HM_GEN/home-files/.zshenv" ~/.zshenv
+        ln -sf "$HM_GEN/home-files/.zprofile" ~/.zprofile
+
         # Symlink .config directories
         mkdir -p ~/.config
         for item in "$HM_GEN/home-files/.config/"*; do
@@ -51,9 +56,14 @@ runs:
         export PATH="$HM_GEN/home-path/bin:$PATH"
         echo "$HM_GEN/home-path/bin" >> "$GITHUB_PATH"
 
+        # Pre-populate sheldon cache (first run clones plugins via git)
+        mkdir -p ~/.cache/sheldon
+        sheldon lock
+        sheldon source > ~/.cache/sheldon/sheldon.zsh
+        readlink ~/.config/sheldon/plugins.toml > ~/.cache/sheldon/sheldon.zsh.lock
+
     # Warm the mise cache BEFORE benchmarking so we measure realistic
-    # warm-start behaviour. Otherwise `mise hook-env` (run from fish's
-    # activation hook on every startup) resolves the dynamic `latest`/`lts`
+    # warm-start behaviour. Otherwise shell activation can resolve dynamic `latest`/`lts`
     # tool versions over the GitHub API inside the measured region, adding
     # 100s of ms of nondeterministic noise that trips the 150% alert.
     # `mise install` lays down the tools so hook-env never touches the

.github/workflows/benchmark-pr.yml

@@ -1,4 +1,4 @@
-name: Fish Startup Benchmark (PR)
+name: Zsh Startup Benchmark (PR)
 
 on:
   pull_request:
@@ -13,7 +13,7 @@ permissions:
 
 jobs:
   benchmark:
-    name: Fish Startup Time
+    name: Zsh Startup Time
     runs-on: macos-latest
     timeout-minutes: 30
     steps:
@@ -30,7 +30,7 @@ jobs:
       - name: Comment benchmark result on PR
         uses: benchmark-action/github-action-benchmark@v1
         with:
-          name: Fish Startup Time
+          name: Zsh Startup Time
           tool: customSmallerIsBetter
           output-file-path: benchmark-result.json
           benchmark-data-dir-path: .

.github/workflows/benchmark.yml

@@ -1,4 +1,4 @@
-name: Fish Startup Benchmark
+name: Zsh Startup Benchmark
 
 on:
   push:
@@ -14,7 +14,7 @@ permissions:
 
 jobs:
   benchmark:
-    name: Fish Startup Time
+    name: Zsh Startup Time
     runs-on: macos-latest
     timeout-minutes: 30
     steps:
@@ -31,7 +31,7 @@ jobs:
       - name: Store benchmark result
         uses: benchmark-action/github-action-benchmark@v1
         with:
-          name: Fish Startup Time
+          name: Zsh Startup Time
           tool: customSmallerIsBetter
           output-file-path: benchmark-result.json
           benchmark-data-dir-path: .

README.md

@@ -48,7 +48,7 @@ macOS dotfiles managed with Nix flakes, nix-darwin, and home-manager.
 7. Reload your shell:
 
    ```bash
-   exec fish
+   exec zsh
    ```
 
 [^1]: The first run may fail. If it does, just run the same command again and it should succeed.

chezmoi/private_Library/private_Application Support/Code/User/settings.json

@@ -79,7 +79,7 @@
   "tailwind-fold.autoFold": false,
   "tailwind-fold.unfoldedTextOpacity": 0.7,
   "terminal.external.osxExec": "Warp.app",
-  "terminal.integrated.defaultProfile.osx": "fish",
+  "terminal.integrated.defaultProfile.osx": "zsh",
   "terminal.integrated.env.osx": {
     "Q_NEW_SESSION": "1"
   },

home/pkgs.nix

@@ -1,6 +1,6 @@
 { pkgs, ... }:
 {
-  # fish, zoxide, eza, fzf, direnv are managed by programs.* modules (home/shell/*.nix)
+  # zoxide, eza, fzf, direnv, starship are managed by programs.* modules (home/shell/*.nix)
   # gh is managed by programs.gh (home/gh.nix)
   home.packages = with pkgs; [
     # Language runtimes & package managers

home/shell/default.nix

@@ -1,14 +1,26 @@
 { ... }:
 {
   imports = [
-    ./fish.nix
+    ./zsh.nix
+    ./starship.nix
     ./zoxide.nix
     ./direnv.nix
     ./mise.nix
     ./eza.nix
     ./fzf.nix
   ];
 
+  # Hardcoded output of `brew shellenv` to avoid spawning brew binary (~15ms).
+  # The output is constant on Apple Silicon, so safe to inline.
+  programs.zsh.profileExtra = ''
+    export HOMEBREW_PREFIX="/opt/homebrew"
+    export HOMEBREW_CELLAR="/opt/homebrew/Cellar"
+    export HOMEBREW_REPOSITORY="/opt/homebrew"
+    export PATH="/opt/homebrew/bin:/opt/homebrew/sbin''${PATH:+:''${PATH}}"
+    export MANPATH="/opt/homebrew/share/man''${MANPATH:+:''${MANPATH}}:"
+    export INFOPATH="/opt/homebrew/share/info:''${INFOPATH:-}"
+  '';
+
   home.sessionPath = [
     "$HOME/bin"
     "$HOME/.local/bin"
@@ -21,6 +33,7 @@
     GH_PAGER = "less -RFX";
     PAGER = "less -RFX";
     PINACT_KEYRING_ENABLED = "true";
-    HOMEBREW_FORBIDDEN_FORMULAE = "node npm pnpm yarn bun deno go awscli bat chezmoi direnv eza fastfetch fd fzf gh lefthook mise turbo zoxide claude ripgrep";
+    HOMEBREW_FORBIDDEN_FORMULAE = "node npm pnpm yarn bun deno go awscli bat chezmoi direnv eza fastfetch fd fzf gh lefthook mise starship turbo zoxide claude ripgrep";
+    ZENO_HOME = "$HOME/.config/zeno";
   };
 }

home/shell/direnv.nix

@@ -2,8 +2,7 @@
 {
   programs.direnv = {
     enable = true;
-    enableFishIntegration = true;
-    enableZshIntegration = false;
+    enableZshIntegration = false; # handled via cache_eval + zsh-defer in zsh.nix
     nix-direnv.enable = true;
   };
 

home/shell/fzf.nix

@@ -2,7 +2,6 @@
 {
   programs.fzf = {
     enable = true;
-    enableFishIntegration = true;
-    enableZshIntegration = false;
+    enableZshIntegration = false; # handled via cache_eval + zsh-defer in zsh.nix
   };
 }