git-sync: sync ~/.codex history repo across machines

Mirror the claude-history setup for Codex: ~/.codex is now a git repo
(github.com/colonelpanic8/codex-history) holding session rollouts and
history.jsonl from all machines, synced by git-sync-rs in watch mode.

- Generalize the nixos host gate (claudeHistoryHosts -> aiHistoryHosts)
  and add codex-history alongside claude-history on both NixOS and darwin.
- Drop the old HM-managed dotfiles/codex/.gitignore; the repo ships its
  own real .gitignore (git won't read a symlinked one).
- Shield dotfiles/codex/* in the root .gitignore so nested codex history
  can't be committed into dotfiles on darwin (where ~/.codex resolves
  into dotfiles/codex).

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

.gitignore

@@ -61,3 +61,11 @@ gotools
 !/dotfiles/claude/settings.json
 !/dotfiles/claude/settings.local.json
 !/dotfiles/claude/settings.local.json.example
+
+# Same story for Codex: ~/.codex resolves into dotfiles/codex on nix-darwin,
+# so the codex-history repo and live Codex state nest inside this worktree.
+# Allowlist only the HM-managed config.
+/dotfiles/codex/*
+!/dotfiles/codex/AGENTS.md
+!/dotfiles/codex/config.toml
+!/dotfiles/codex/skills

dotfiles/codex/.gitignore

@@ -1,8 +0,0 @@
-*
-!.gitignore
-!AGENTS.md
-!config.toml
-!skills
-
-# Legacy generated/local Codex state under this repo stays ignored. Active
-# host-local Codex fragments now live under ~/.codex.

nix-darwin/home/git-sync.nix

@@ -11,6 +11,7 @@
   orgPath = "${config.home.homeDirectory}/org";
   passwordStorePath = "${config.home.homeDirectory}/.password-store";
   claudePath = "${config.home.homeDirectory}/.claude";
+  codexPath = "${config.home.homeDirectory}/.codex";
 in {
   services.git-sync = {
     enable = true;
@@ -30,6 +31,11 @@ in {
         uri = "git@github.com:colonelpanic8/claude-history.git";
         interval = 600;
       };
+      codex-history = {
+        path = codexPath;
+        uri = "git@github.com:colonelpanic8/codex-history.git";
+        interval = 600;
+      };
     };
   };
 
@@ -43,5 +49,7 @@ in {
     # untracked session files and throttle event-driven syncs.
     git-sync-claude-history.config.ProgramArguments =
       lib.mkForce ["${gitSyncPackage}/bin/git-sync-rs" "-d" claudePath "watch" "--new-files" "true" "--min-interval" "300"];
+    git-sync-codex-history.config.ProgramArguments =
+      lib.mkForce ["${gitSyncPackage}/bin/git-sync-rs" "-d" codexPath "watch" "--new-files" "true" "--min-interval" "300"];
   };
 }

nixos/git-sync.nix

@@ -5,11 +5,11 @@
   ...
 }: let
   gitSyncServicePath = lib.makeBinPath [pkgs.coreutils pkgs.git pkgs.openssh];
-  # ~/.claude history sync is being rolled out machine-by-machine; each new
+  # AI chat-history sync (Claude Code + Codex) is rolled out machine-by-machine;
-  # machine needs its existing history merged into the repo first (see
+  # each new machine needs its existing history merged into the repo first (see
-  # github.com/colonelpanic8/claude-history).
+  # github.com/colonelpanic8/claude-history and .../codex-history).
-  claudeHistoryHosts = ["ryzen-shine" "railbird-sf" "jay-lenovo" "strixi-minaj"];
+  aiHistoryHosts = ["ryzen-shine" "railbird-sf" "jay-lenovo" "strixi-minaj"];
-  syncClaudeHistory = builtins.elem config.networking.hostName claudeHistoryHosts;
+  syncAiHistory = builtins.elem config.networking.hostName aiHistoryHosts;
   mkGitSyncTrayOverrides = icon: {
     Service = {
       Environment = lib.mkMerge [
@@ -40,12 +40,17 @@ in {
           uri = "git@github.com:IvanMalison/.password-store.git";
         };
       }
-      // lib.optionalAttrs syncClaudeHistory {
+      // lib.optionalAttrs syncAiHistory {
         claude-history = {
           path = config.home.homeDirectory + "/.claude";
           uri = "git@github.com:colonelpanic8/claude-history.git";
           interval = 600;
         };
+        codex-history = {
+          path = config.home.homeDirectory + "/.codex";
+          uri = "git@github.com:colonelpanic8/codex-history.git";
+          interval = 600;
+        };
       };
     };
 
@@ -55,13 +60,16 @@ in {
           lib.nameValuePair "git-sync-${name}"
           (mkGitSyncTrayOverrides (repoIcons.${name} or "git")))
         config.services.git-sync.repositories)
-      (lib.optionalAttrs syncClaudeHistory {
+      (lib.optionalAttrs syncAiHistory {
         # Live sessions append to their transcript on every message; sync
         # untracked session files and throttle event-driven syncs so an
         # active session doesn't push once per append.
         git-sync-claude-history.Service.ExecStart =
           lib.mkForce
           "${pkgs.git-sync-rs}/bin/git-sync-rs watch --new-files true --min-interval 300";
+        git-sync-codex-history.Service.ExecStart =
+          lib.mkForce
+          "${pkgs.git-sync-rs}/bin/git-sync-rs watch --new-files true --min-interval 300";
       })
     ];
   };