Oi: workspace detection instead of raw pwd

- Walk up from pwd looking for workspace indicators (.mdworkspace)
- Skip submodules (.git file with /modules/), stop at worktrees
- Fall back to nearest real git root (.git directory)
- Error if not in any git repo or workspace

scripts/Oi

@@ -10,8 +10,40 @@ die() { printf '%s: %s\n' "$cmd" "$*" >&2; exit 1; }
 OLLIE=${OLLIE:-$HOME/mnt/ollie}
 try() { "$@" 2>/dev/null || { ollie-remount && "$@"; }; }
 
-# Derive deterministic session name from cwd
-cwd=$(pwd)
+# Workspace detection: find workspace root (indicator file) or git/worktree root.
+# Indicators: comma-delimited list of filenames that mark a workspace.
+WORKSPACE_INDICATORS=".mdworkspace"
+
+detect_workspace() {
+	local dir="$1"
+	local git_root=""
+
+	while [ "$dir" != "/" ]; do
+		# Check for workspace indicator
+		local IFS=,
+		for ind in $WORKSPACE_INDICATORS; do
+			[ -e "$dir/$ind" ] && { printf '%s\n' "$dir"; return; }
+		done
+		unset IFS
+		# Check for .git
+		if [ -z "$git_root" ] && [ -e "$dir/.git" ]; then
+			if [ -d "$dir/.git" ]; then
+				# Real repo — this is a root
+				git_root="$dir"
+			elif ! grep -q '/modules/' "$dir/.git" 2>/dev/null; then
+				# Worktree (.git file pointing to .git/worktrees/) — treat as root
+				git_root="$dir"
+			fi
+			# Submodule (.git file pointing to .git/modules/) — skip
+		fi
+		dir=$(dirname "$dir")
+	done
+
+	[ -n "$git_root" ] && { printf '%s\n' "$git_root"; return; }
+	return 1
+}
+
+cwd=$(detect_workspace "$(pwd)") || die "not in a git repo or workspace"
 hash=$(printf '%s' "$cwd" | cksum | awk '{print $1}')
 NAV_NAME="nav-${hash}"
 NAV_PATH="$OLLIE/s/$NAV_NAME"