{"record":{"id":"57a604a41eca2838","repo":"atuinsh/atuin","slug":"output-capture-delete-task-panicked","errorCode":null,"errorMessage":"output-capture delete task panicked","messagePattern":"output-capture delete task panicked","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"critical","filePath":"crates/atuin-daemon/src/output_capture/backend/fjall/mod.rs","lineNumber":132,"sourceCode":"        let dirty = self.dirty.clone();\n        tokio::task::spawn_blocking(move || {\n            let mut tx = db.write_tx().map_err(|err| DeleteOutputError::Storage(Box::new(err)))?;\n            for key in keys {\n                tx.remove(&keyspace, key);\n            }\n            match tx.commit().map_err(|err| DeleteOutputError::Storage(Box::new(err)))? {\n                Ok(()) => {\n                    dirty.store(true, Ordering::Release);\n                    Ok(())\n                }\n                // fjall only reports conflicts for transactions that read; this one never does.\n                Err(fjall::Conflict) => {\n                    unreachable!(\"a blind remove performs no reads, so it can never conflict\")\n                }\n            }\n        })\n        .await\n        .expect(\"output-capture delete task panicked\")\n    }\n\n    /// Deletes the oldest stored entries until their values total at least `reclaim_bytes`,\n    /// returning the number of bytes actually freed.\n    async fn reclaim(&self, reclaim_bytes: u64) -> Result<u64, DeleteOutputError> {\n        if reclaim_bytes == 0 {\n            return Ok(0);\n        }\n\n        let db = self.db.clone();\n        let keyspace = self.keyspace.clone();\n        let dirty = self.dirty.clone();\n        tokio::task::spawn_blocking(move || {\n            let mut tx = db.write_tx().map_err(|err| DeleteOutputError::Storage(Box::new(err)))?;\n            let mut freed: u64 = 0;\n\n            for guard in keyspace.inner().iter() {\n                let (key, value) =","sourceCodeStart":114,"sourceCodeEnd":150,"githubUrl":"https://github.com/atuinsh/atuin/blob/c0c717ab04c881764bcad4b3d169a507e2432643/crates/atuin-daemon/src/output_capture/backend/fjall/mod.rs#L114-L150","documentation":"This message is the `.expect()` on the `JoinHandle` returned by `spawn_blocking` inside `FjallBackendInner::remove` (crates/atuin-daemon/src/output_capture/backend/fjall/mod.rs:132). It means the blocking task performing the batched key deletion panicked before returning its Result. The closure's own fallible paths return `DeleteOutputError::Storage`, so this panic almost always comes from the `unreachable!(\"a blind remove performs no reads, so it can never conflict\")` branch firing on `fjall::Conflict`, or a task-abort JoinError — not from ordinary delete failures.","triggerScenarios":"Calling the backend's `remove(ids)` when: (1) fjall unexpectedly reports `Conflict` on the blind (read-free) remove transaction, hitting the `unreachable!()`; (2) `tx.remove`/keyspace operations panic inside fjall; (3) the blocking task is cancelled at shutdown (JoinError) which `.expect()` also turns into this panic.","commonSituations":"Bulk-deleting output captures for pruned history entries; garbage collection racing heavy concurrent writers on the same keyspace under a fjall version whose optimistic transactions behave differently than assumed; daemon shutdown mid-operation.","solutions":["Check the fjall crate version against the one atuin-daemon pinned; if a newer fjall changed Conflict semantics for read-free transactions, upgrade/downgrade to a compatible version","Report/inspect the JoinError payload to confirm whether the panic is the `unreachable!()` Conflict branch — if so it is a fjall internal assumption bug, not user error","Retry the removal after restarting the daemon; transient conflict behavior may not recur","Delete the affected entries individually instead of in one batched transaction to isolate which key triggers the conflict"],"exampleFix":"// before\nErr(fjall::Conflict) => {\n    unreachable!(\"a blind remove performs no reads, so it can never conflict\")\n}\n// after: surface the conflict instead of panicking\nErr(fjall::Conflict) => Err(DeleteOutputError::Storage(\n    \"unexpected conflict on blind remove\".into(),\n)),","handlingStrategy":"retry","validationCode":"// Pre-check that the ids exist so the remove path does the minimal\n// blind transaction; empty ids short-circuit before any task spawn.\nlet existing: Vec<_> = ids.into_iter().filter(|id| capture_store.get(*id).ok().flatten().is_some()).collect();","typeGuard":"fn is_clean_result(r: &Result<(), DeleteOutputError>) -> bool {\n    !matches!(r, Err(DeleteOutputError::Storage(_)))\n}","tryCatchPattern":"// Run the removal in a supervised child task; a panic becomes a\n// retryable JoinError instead of killing the caller.\nmatch tokio::spawn(backend.remove(ids.clone())).await {\n    Ok(Ok(())) => {},\n    Ok(Err(e)) | Err(_) => schedule_retry(ids, e),\n}","preventionTips":["Pin the fjall version atuin-daemon was tested against; review its CHANGELOG for transaction-conflict semantics changes","Avoid running concurrent bulk deletes and heavy writes; serialize destructive maintenance","Verify data-dir integrity after any crash before resuming deletion workloads","Keep the daemon shutdown graceful so blocking delete tasks are not cancelled mid-transaction"],"tags":["panic","storage","fjall","tokio","deletion"],"backgroundTag":"internal-invariant-violation","analyzedSha":"c0c717ab04c881764bcad4b3d169a507e2432643","analyzedAt":"2026-09-12T07:40:01.341Z","contentChangedAt":"2026-09-12T07:40:01.341Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}