diff --git a/CLAUDE.md b/CLAUDE.md
index 149df6a..179b3a9 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -106,7 +106,7 @@ Pre-alpha. No users, no released builds, no data to migrate. Breaking changes to
 - Task deduplication on load (handles sync conflict duplicates)
 - Subtask hierarchy: subtask count shown on parent tasks in list, subtask detail via three-panel slide navigation, inline add at top of subtask list (new subtasks prepend), collapsible completed subtasks section, cascade delete (parent deletion removes all subtasks with confirmation warning)
 - Custom confirmation dialogs (ConfirmDialog component replaces native confirm())
-- Workspace path validation (rejects system directories)
+- Workspace path validation (rejects filesystem root `/` and system directories: `/etc`, `/usr`, `/bin`, `/sbin`, `/var`, `/proc`, `/sys`, `/dev`)
 - Task detail auto-cleanup (taskStack clears when viewed task is deleted or list switches)
 - Swipe gestures on mobile: swipe left/right on a task to toggle completion (swipe direction depends on current status)
 - Accessibility: ARIA labels/roles on interactive components, keyboard handlers, `prefers-reduced-motion` CSS support
diff --git a/docs/API.md b/docs/API.md
index f8b3c1d..b8d2435 100644
--- a/docs/API.md
+++ b/docs/API.md
@@ -454,7 +454,7 @@ All metadata and state files use an atomic write pattern (write to `.tmp` then r
 
 - **List names**: Rejected if they contain `/`, `\`, or `..` components. Canonicalized and verified to stay within workspace root.
 - **Sync paths**: Validated to reject `..` components and backslashes anywhere in the path before any file system operation.
-- **Workspace paths** (Tauri): Rejected if they point to system directories (`/etc`, `/usr`, `/bin`, etc.).
+- **Workspace paths** (Tauri): Rejected if they point to the filesystem root (`/`) or system directories (`/etc`, `/usr`, `/bin`, `/sbin`, `/var`, `/proc`, `/sys`, `/dev`).
 - **Filenames**: Sanitized to replace `/ \ : * ? " < > |` and control characters with `_`.
 
 ## Example: Complete Workflow