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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[High][store] notifySubscribers iterates live array → subscribers skipped on unsubscribe-during-notify","articleBody":"## Severity: 🟠 High (correctness)\n\n## Location\n[`src/store/create-store.ts:157-159`](../blob/main/src/store/create-store.ts#L157-L159) (`notifySubscribers`); unsubscribe splices at `:352-360`.\n\n## Description\n`$subscribe` stores callbacks in a `subscribers` array and returns an unsubscribe that `splice`s the callback out. `notifySubscribers` iterates that **live** array:\n```ts\nfor (const callback of subscribers) {\n  callback(currentState);\n}\n```\nIf any callback unsubscribes itself (or another subscriber) during notification, the `splice` shifts indices under the `for…of` iterator, so the next subscriber is **silently skipped** for that notification cycle (and a newly-subscribed one may be double-invoked). A watcher that self-detaches on a condition is a common pattern, so this is readily triggered.\n\nNote that [`$onAction` already guards against exactly this](../blob/main/src/store/create-store.ts#L274) with `const listenerSnapshot = [...actionListeners];` — `notifySubscribers` is simply missing the same treatment.\n\n## Reproduction\n```ts\nconst store = createStore({ id: 's', state: () =\u003e ({ n: 0 }) });\nconst unsubA = store.$subscribe(() =\u003e unsubA());   // self-detaches on first notify\nconst seen = [];\nstore.$subscribe(() =\u003e seen.push('B'));            // registered after A\nstore.n = 1;                                        // A runs, splices itself, B is skipped\n// seen === []  (B should have fired)\n```\n\n## Suggested fix\nSnapshot before iterating, matching the `$onAction` pattern:\n```ts\nfor (const callback of [...subscribers]) {\n  callback(currentState);\n}\n```\n\n---\n_Filed as part of a full-codebase security \u0026 correctness audit._\n","author":{"url":"https://github.com/JosunLP","@type":"Person","name":"JosunLP"},"datePublished":"2026-07-05T17:02:47.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/165/bQuery/issues/165"}