private structures

db.js

@@ -203,10 +203,74 @@ function createStructure(name, userId) {
   const stmt = db.prepare(
     "INSERT INTO structures (name, user_id) VALUES (?, ?)",
   );
-  const info = stmt.run(name, userId);
+  const info = stmt.run(name, userId ?? null);
   return info.lastInsertRowid; // Returns the structure_id of the newly created structure
 }
 
+// ---- access control (private structures) --------------------------------
+//
+// A structure is public unless `private` is set. Access to a private structure
+// is exactly its member list (structure_members) — a flat set of equals, no
+// creator or owner. Anyone on the list can reach it, edit it, manage the list,
+// or make it public again. This is the single source of truth the platform
+// consults before serving a user route, mounting a db, or opening the workshop
+// — never the structure's own code.
+
+function isMember(structureId, userId) {
+  return !!db
+    .prepare(
+      "SELECT 1 FROM structure_members WHERE structure_id = ? AND user_id = ?",
+    )
+    .get(structureId, userId);
+}
+
+function canAccessStructure(userId, structureId) {
+  const s = getStructure(structureId);
+  if (!s) return false;
+  if (!s.private) return true;
+  if (userId == null) return false;
+  return isMember(structureId, userId);
+}
+
+// Members of a structure, with their usernames, for the settings UI.
+function getMembers(structureId) {
+  return db
+    .prepare(
+      `SELECT sv.user_id, u.username, sv.created_at
+       FROM structure_members sv
+       JOIN users u ON u.id = sv.user_id
+       WHERE sv.structure_id = ?
+       ORDER BY sv.created_at ASC`,
+    )
+    .all(structureId);
+}
+
+function addMember(structureId, userId) {
+  db.prepare(
+    "INSERT OR IGNORE INTO structure_members (structure_id, user_id) VALUES (?, ?)",
+  ).run(structureId, userId);
+}
+
+function removeMember(structureId, userId) {
+  db.prepare(
+    "DELETE FROM structure_members WHERE structure_id = ? AND user_id = ?",
+  ).run(structureId, userId);
+}
+
+// Set a structure's privacy. Anyone may lock any structure down; the actor is
+// added to the member list so they don't shut themselves out. (Access is purely
+// the member set, so without this the person who flipped it private would lose
+// the very structure they just privatized.)
+function setStructurePrivacy(structureId, isPrivate, actorUserId) {
+  const s = getStructure(structureId);
+  if (!s) return;
+  db.prepare("UPDATE structures SET private = ? WHERE id = ?").run(
+    isPrivate ? 1 : 0,
+    structureId,
+  );
+  if (isPrivate && actorUserId != null) addMember(structureId, actorUserId);
+}
+
 function createRoute(verb, path, structureId, handler) {
   path = encodeURI(path);
 
@@ -769,6 +833,12 @@ module.exports = {
   getStructures,
   getStructure,
   createStructure,
+  canAccessStructure,
+  isMember,
+  getMembers,
+  addMember,
+  removeMember,
+  setStructurePrivacy,
   createRoute,
   getRoutes,
   getRoute,