fix(security): fix media upload permission denied + symlink protection

- Fix workspace dir ownership in Docker entrypoint: chown dirs not owned
  by goclaw on startup (handles dirs created by root in previous lifecycle)
- Add symlink check on .uploads/ via os.Lstat before file creation to
  prevent symlink-based attacks replacing .uploads with link to sensitive dir

docker-entrypoint.sh

@@ -19,6 +19,15 @@ if [ "$(id -u)" = "0" ] && [ -d "$RUNTIME_DIR" ]; then
   chown -R goclaw:goclaw "$RUNTIME_DIR/pip" "$RUNTIME_DIR/npm-global" "$RUNTIME_DIR/pip-cache" 2>/dev/null || true
 fi
 
+# Fix workspace directory ownership: handle dirs created by root in previous
+# container lifecycle or via manual docker exec.
+# Security: -type d = real directories only (not symlinks).
+# find default -P mode = never follow symlinks. -maxdepth 5 limits traversal.
+if [ "$(id -u)" = "0" ] && [ -d /app/workspace ]; then
+  find /app/workspace -maxdepth 5 -type d -not -user goclaw \
+    -exec chown goclaw:goclaw {} + 2>/dev/null || true
+fi
+
 # Python: allow agent to pip install to writable target dir
 export PYTHONPATH="$RUNTIME_DIR/pip:${PYTHONPATH:-}"
 export PIP_TARGET="$RUNTIME_DIR/pip"

internal/agent/media.go

@@ -70,6 +70,12 @@ func (l *Loop) persistMedia(sessionKey string, files []bus.MediaFile, workspace
 		slog.Warn("media: failed to create .uploads dir", "dir", uploadsDir, "error", err)
 		return nil
 	}
+	// Verify .uploads is a real directory (not symlink) to prevent symlink-based attacks.
+	// os.Lstat does NOT follow symlinks — rejects if attacker replaced .uploads with a symlink.
+	if fi, err := os.Lstat(uploadsDir); err == nil && fi.Mode()&os.ModeSymlink != 0 {
+		slog.Warn("media: .uploads is a symlink, refusing to use", "dir", uploadsDir)
+		return nil
+	}
 
 	var refs []providers.MediaRef
 	for _, f := range files {