fix(close): a read-only brain writes no clean-shutdown evidence — the marker is the writer's word about itself

src/brainy.ts

@@ -20486,9 +20486,22 @@ export class Brainy<T = any> implements BrainyInterface<T> {
           await this._aggregationIndex.flush()
         }
       })(),
-      // 8.0 MVCC: detach the generation-bump hook and persist the counter
+      // 8.0 MVCC: detach the generation-bump hook and persist the counter.
+      // READ-ONLY GUARD: a reader's open() never sets the bump hook, never
+      // buffers pending single-ops, and — since generationStore.open() also
+      // leaves the clean-shutdown marker untouched for a reader — never
+      // consumes it either, so there is nothing of a writer's to persist or
+      // release here. Calling close() anyway would still WRITE: it
+      // unconditionally re-stamps `_system/clean-shutdown.json` (and can
+      // advance the fold checkpoint / counter files) at the generation this
+      // session merely observed — a reader vouching for a commit it never
+      // made. The marker is the writer's own evidence about the writer's own
+      // process; a read-only brain must leave `_system/` exactly as it found
+      // it. (Mirrors the same guard already applied to every other Phase-1
+      // step below, and to the signal-path shutdown in
+      // registerShutdownHooks().)
       (async () => {
-        if (this.generationStore) {
+        if (this.generationStore && !this.isReadOnly) {
           await this.generationStore.close()
         }
       })()