[AI] Improve post-checkout hook to handle git worktree creation (#7393)

* [AI] Add worktree creation hook to run yarn install

Add a WorktreeCreate hook in .claude/settings.json that runs a setup
script after creating a new git worktree. The script creates a detached
worktree and runs yarn install to ensure dependencies are available.

https://claude.ai/code/session_01MjuJLWcxNU6nbWQDrgGpPr

* [AI] Move worktree setup hook to husky post-checkout for universal support

Instead of a Claude Code-specific hook, detect new worktree creation in
the existing husky post-checkout hook by checking for missing node_modules.
This works with any tool that creates git worktrees (Claude Code, Cursor,
CLI, etc.) since git runs post-checkout after worktree creation.

https://claude.ai/code/session_01MjuJLWcxNU6nbWQDrgGpPr

* Add release notes for PR #7393

* Update 7393.md

* [AI] Fix post-checkout hook to propagate yarn install failures

Co-authored-by: Matiss Janis Aboltins <[email protected]>

---------

Co-authored-by: Claude <[email protected]>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Cursor Agent <[email protected]>
Co-authored-by: Matiss Janis Aboltins <[email protected]>

.husky/post-checkout

@@ -1,11 +1,19 @@
 #!/bin/sh
 # Run yarn install when switching branches (if yarn.lock changed)
+# or when creating a new worktree (node_modules won't exist yet)
 
 # $3 is 1 for branch checkout, 0 for file checkout
 if [ "$3" != "1" ]; then
   exit 0
 fi
 
+# Worktree creation: node_modules doesn't exist yet, always install
+if [ ! -d "node_modules" ]; then
+  echo "New worktree detected — running yarn install..."
+  yarn install || exit 1
+  exit 0
+fi
+
 # Check if yarn.lock changed between the old and new HEAD
 if git diff --name-only "$1" "$2" | grep -q "^yarn.lock$"; then
   echo "yarn.lock changed — running yarn install..."

upcoming-release-notes/7393.md

@@ -0,0 +1,6 @@
+---
+category: Maintenance
+authors: [MatissJanis]
+---
+
+Improve post-checkout hook to automatically install dependencies for newly created git worktrees.