diff --git a/README.md b/README.md
index bafd62d..9f955ef 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,8 @@
 # fn-design-system
 
-**Read-only mirror of `@fn_library`** — the React 19 + Mantine v9 design system that lives inside [fn_registry](../fn_registry).
+**Read-only mirror of `@fn_library`** — the React 19 + Mantine v9 design system that lives inside [fn_registry](../..).
+
+This repo is checked out at `fn_registry/subrepos/fn-design-system/` (gitignored by fn_registry so it keeps its own git history and remotes).
 
 This repo exists for one purpose: **give Claude Design (and other external tools) a clean, minimal view of the design system** without exposing the rest of the monorepo.
 
@@ -42,7 +44,7 @@ git commit -m "sync: <what changed>"
 git push
 ```
 
-The script requires `FN_REGISTRY_ROOT` to point at your local fn_registry clone (defaults to `~/fn_registry`).
+The script auto-detects the fn_registry root when the mirror lives at `fn_registry/subrepos/fn-design-system/`. Override with `FN_REGISTRY_ROOT=/path/to/fn_registry` if needed.
 
 ## What is NOT in this repo
 
diff --git a/sync_from_registry.sh b/sync_from_registry.sh
index 51b581a..08f43aa 100755
--- a/sync_from_registry.sh
+++ b/sync_from_registry.sh
@@ -6,13 +6,24 @@
 #   fn_registry/frontend/package.json (filtered) → package.json (not overwritten)
 #
 # Usage:
-#   FN_REGISTRY_ROOT=~/fn_registry ./sync_from_registry.sh
-#   ./sync_from_registry.sh   # uses default ~/fn_registry
+#   ./sync_from_registry.sh                              # auto-detects when inside fn_registry/subrepos/
+#   FN_REGISTRY_ROOT=/path/to/fn_registry ./sync_from_registry.sh
 
 set -euo pipefail
 
 MIRROR_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-REGISTRY_ROOT="${FN_REGISTRY_ROOT:-$HOME/fn_registry}"
+
+# Resolve fn_registry root:
+#   1. $FN_REGISTRY_ROOT if set
+#   2. two levels up from script (mirror at fn_registry/subrepos/fn-design-system/)
+#   3. $HOME/fn_registry as last resort
+if [[ -n "${FN_REGISTRY_ROOT:-}" ]]; then
+  REGISTRY_ROOT="$FN_REGISTRY_ROOT"
+elif [[ -d "$MIRROR_ROOT/../../frontend/functions/ui" ]]; then
+  REGISTRY_ROOT="$(cd "$MIRROR_ROOT/../.." && pwd)"
+else
+  REGISTRY_ROOT="$HOME/fn_registry"
+fi
 
 if [[ ! -d "$REGISTRY_ROOT/frontend/functions/ui" ]]; then
   echo "ERROR: $REGISTRY_ROOT/frontend/functions/ui not found." >&2
@@ -20,6 +31,8 @@ if [[ ! -d "$REGISTRY_ROOT/frontend/functions/ui" ]]; then
   exit 1
 fi
 
+echo "→ Registry root: $REGISTRY_ROOT"
+
 SRC_UI="$REGISTRY_ROOT/frontend/functions/ui"
 SRC_DOC="$REGISTRY_ROOT/frontend/DESIGN_SYSTEM.md"
 DST_UI="$MIRROR_ROOT/components"