Improve git worktree session workflow

layouts/session-project

@@ -0,0 +1,35 @@
+#!/usr/bin/env zsh
+
+# usage: session-project <project>
+#
+# Layout for a session created by `session -p <project>`, where <project> is a
+# path in ~/Projects with the prefix removed. The session-created hook passes
+# the project along, taking it from the session environment.
+
+project=$1
+repo=$HOME/Projects/$project
+
+tmux rename-window home
+$(dirname $0)/window-auto
+
+# Without a project there is nothing but the home window, which is all a
+# session created directly from this layout's name can get.
+if [[ -z "$project" ]] || ! git -C "$repo" rev-parse --git-dir &>/dev/null; then
+  exit
+fi
+
+# The remote's default branch, falling back to whatever HEAD points at for
+# repositories without an origin/HEAD, e.g. those with no remote at all.
+branch=$(git -C "$repo" symbolic-ref --short refs/remotes/origin/HEAD 2>/dev/null)
+branch=${branch#origin/}
+if [[ -z "$branch" ]]; then
+  branch=$(git -C "$repo" symbolic-ref --short HEAD 2>/dev/null)
+fi
+if [[ -z "$branch" ]]; then
+  # Detached HEAD, name the window after the commit it sits on.
+  branch=$(git -C "$repo" rev-parse --short HEAD 2>/dev/null)
+fi
+
+tmux new-window -c "$repo"
+tmux rename-window "$branch"
+$(dirname $0)/window-auto