Option 1 of #157, first slice. Search walked and read the brain by path, so a symlink planted in the Syncthing-shared brain dir put an outside file's contents in brain_query results, and a FIFO swapped into the wiki hung the query forever (reproduced: the FIFO race test blocked for the full 6s timeout before this change). New package internal/brainfs: Open (os.Root on the brain dir), ReadRegular (Lstat + non-blocking open + type check on the handle) and WalkRegular (walks the root's FS, yields regular files only, never follows a link). search.Query and hydrate use it. Tests (red first): a wiki symlink is not followed, a symlinked dir is not descended, hydrate refuses a symlink, and race tests swap a symlink or a FIFO into a wiki note while Query loops; any leaked byte or a hang fails. Refs #157 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>