diff --git a/lez/indexer/core/src/block_store.rs b/lez/indexer/core/src/block_store.rs
index 617c4c60..a101bf94 100644
--- a/lez/indexer/core/src/block_store.rs
+++ b/lez/indexer/core/src/block_store.rs
@@ -13,6 +13,8 @@ use logos_blockchain_zone_sdk::Slot;
 use storage::indexer::RocksDBIO;
 use tokio::sync::RwLock;
 
+use crate::chain_breaker::ChainBreaker;
+
 #[derive(Clone)]
 pub struct IndexerStore {
     dbio: Arc<RocksDBIO>,
@@ -113,6 +115,21 @@ impl IndexerStore {
         Ok(())
     }
 
+    pub fn get_chain_breaker(&self) -> Result<Option<ChainBreaker>> {
+        let Some(bytes) = self.dbio.get_chain_breaker_bytes()? else {
+            return Ok(None);
+        };
+        let breaker: Option<ChainBreaker> =
+            serde_json::from_slice(&bytes).context("Failed to deserialize stored chain breaker")?;
+        Ok(breaker)
+    }
+
+    pub fn set_chain_breaker(&self, breaker: &Option<ChainBreaker>) -> Result<()> {
+        let bytes = serde_json::to_vec(breaker).context("Failed to serialize chain breaker")?;
+        self.dbio.put_chain_breaker_bytes(&bytes)?;
+        Ok(())
+    }
+
     /// Recalculation of final state directly from DB.
     ///
     /// Used for indexer healthcheck.
@@ -197,6 +214,43 @@ impl IndexerStore {
     }
 }
 
+#[cfg(test)]
+mod chain_breaker_tests {
+    use common::HashType;
+
+    use super::*;
+    use crate::{chain_breaker::ChainBreaker, ingest_error::BlockIngestError};
+
+    #[tokio::test]
+    async fn chain_breaker_roundtrips_and_clears() {
+        let dir = tempfile::tempdir().expect("tempdir");
+        let store = IndexerStore::open_db(dir.path()).expect("open store");
+
+        assert!(store.get_chain_breaker().expect("get").is_none());
+
+        let breaker = ChainBreaker {
+            block_id: Some(7),
+            block_hash: Some(HashType([1_u8; 32])),
+            prev_block_hash: Some(HashType([2_u8; 32])),
+            l1_slot: serde_json::Value::Null,
+            error: BlockIngestError::StateTransition("boom".to_owned()),
+            first_seen: Some(99),
+            orphans_since: 3,
+        };
+        store
+            .set_chain_breaker(&Some(breaker))
+            .expect("set breaker");
+
+        let got = store.get_chain_breaker().expect("get").expect("present");
+        assert_eq!(got.block_id, Some(7));
+        assert_eq!(got.orphans_since, 3);
+        assert!(matches!(got.error, BlockIngestError::StateTransition(_)));
+
+        store.set_chain_breaker(&None).expect("clear");
+        assert!(store.get_chain_breaker().expect("get").is_none());
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use common::{HashType, block::HashableBlockData};
diff --git a/lez/indexer/core/src/chain_breaker.rs b/lez/indexer/core/src/chain_breaker.rs
new file mode 100644
index 00000000..7aacbd79
--- /dev/null
+++ b/lez/indexer/core/src/chain_breaker.rs
@@ -0,0 +1,23 @@
+use common::HashType;
+use serde::{Deserialize, Serialize};
+
+use crate::ingest_error::BlockIngestError;
+
+/// Diagnostic record of the first block that broke the L2 chain.
+///
+/// Later non-chaining blocks (orphans, since the tip is frozen) only bump `orphans_since`.
+///
+/// The block-derived fields are `None` for a deserialize break (no header was
+/// ever parsed). `l1_slot` is the zone-sdk cursor position captured as JSON.
+/// `first_seen` is the breaking block's L2 timestamp (`None` for a deserialize break).
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ChainBreaker {
+    pub block_id: Option<u64>,
+    pub block_hash: Option<HashType>,
+    pub prev_block_hash: Option<HashType>,
+    pub l1_slot: serde_json::Value,
+    pub error: BlockIngestError,
+    pub first_seen: Option<u64>,
+    pub orphans_since: u64,
+}
diff --git a/lez/indexer/core/src/lib.rs b/lez/indexer/core/src/lib.rs
index 35ff3c6b..a48712fd 100644
--- a/lez/indexer/core/src/lib.rs
+++ b/lez/indexer/core/src/lib.rs
@@ -2,6 +2,7 @@ use std::{path::Path, sync::Arc};
 
 use anyhow::Result;
 use arc_swap::ArcSwap;
+pub use chain_breaker::ChainBreaker;
 use common::block::Block;
 // ToDo: Remove after testnet
 use futures::StreamExt as _;
@@ -18,6 +19,7 @@ use crate::{
     status::{IndexerStatus, IndexerSyncStatus},
 };
 pub mod block_store;
+pub mod chain_breaker;
 pub mod config;
 pub mod ingest_error;
 pub mod status;
diff --git a/lez/storage/src/indexer/indexer_cells.rs b/lez/storage/src/indexer/indexer_cells.rs
index b19a5510..84379a1d 100644
--- a/lez/storage/src/indexer/indexer_cells.rs
+++ b/lez/storage/src/indexer/indexer_cells.rs
@@ -7,9 +7,9 @@ use crate::{
     error::DbError,
     indexer::{
         ACC_NUM_CELL_NAME, BLOCK_HASH_CELL_NAME, BREAKPOINT_CELL_NAME, CF_ACC_META,
-        CF_BREAKPOINT_NAME, CF_HASH_TO_ID, CF_TX_TO_ID, DB_META_LAST_BREAKPOINT_ID,
-        DB_META_LAST_OBSERVED_L1_LIB_HEADER_ID_IN_DB_KEY, DB_META_ZONE_SDK_INDEXER_CURSOR_KEY,
-        TX_HASH_CELL_NAME,
+        CF_BREAKPOINT_NAME, CF_HASH_TO_ID, CF_TX_TO_ID, DB_META_CHAIN_BREAKER_KEY,
+        DB_META_LAST_BREAKPOINT_ID, DB_META_LAST_OBSERVED_L1_LIB_HEADER_ID_IN_DB_KEY,
+        DB_META_ZONE_SDK_INDEXER_CURSOR_KEY, TX_HASH_CELL_NAME,
     },
 };
 
@@ -247,6 +247,41 @@ impl SimpleWritableCell for ZoneSdkIndexerCursorCellRef<'_> {
     }
 }
 
+/// Opaque JSON bytes for the indexer's persisted `Option<ChainBreaker>`.
+/// Serialized via `serde_json` by the caller (mirrors the zone-sdk cursor cell).
+#[derive(BorshDeserialize)]
+pub struct ChainBreakerCellOwned(pub Vec<u8>);
+
+impl SimpleStorableCell for ChainBreakerCellOwned {
+    type KeyParams = ();
+
+    const CELL_NAME: &'static str = DB_META_CHAIN_BREAKER_KEY;
+    const CF_NAME: &'static str = CF_META_NAME;
+}
+
+impl SimpleReadableCell for ChainBreakerCellOwned {}
+
+#[derive(BorshSerialize)]
+pub struct ChainBreakerCellRef<'bytes>(pub &'bytes [u8]);
+
+impl SimpleStorableCell for ChainBreakerCellRef<'_> {
+    type KeyParams = ();
+
+    const CELL_NAME: &'static str = DB_META_CHAIN_BREAKER_KEY;
+    const CF_NAME: &'static str = CF_META_NAME;
+}
+
+impl SimpleWritableCell for ChainBreakerCellRef<'_> {
+    fn value_constructor(&self) -> DbResult<Vec<u8>> {
+        borsh::to_vec(&self).map_err(|err| {
+            DbError::borsh_cast_message(
+                err,
+                Some("Failed to serialize chain breaker cell".to_owned()),
+            )
+        })
+    }
+}
+
 #[cfg(test)]
 mod uniform_tests {
     use crate::{
diff --git a/lez/storage/src/indexer/mod.rs b/lez/storage/src/indexer/mod.rs
index f74a9c64..97362e8b 100644
--- a/lez/storage/src/indexer/mod.rs
+++ b/lez/storage/src/indexer/mod.rs
@@ -24,6 +24,8 @@ pub const DB_META_LAST_OBSERVED_L1_LIB_HEADER_ID_IN_DB_KEY: &str =
 pub const DB_META_LAST_BREAKPOINT_ID: &str = "last_breakpoint_id";
 /// Key base for storing the zone-sdk indexer cursor (opaque bytes).
 pub const DB_META_ZONE_SDK_INDEXER_CURSOR_KEY: &str = "zone_sdk_indexer_cursor";
+/// Key base for storing the persisted `Option<ChainBreaker>` diagnostic record (opaque JSON bytes).
+pub const DB_META_CHAIN_BREAKER_KEY: &str = "chain_breaker";
 
 /// Cell name for a breakpoint.
 pub const BREAKPOINT_CELL_NAME: &str = "breakpoint";
diff --git a/lez/storage/src/indexer/read_once.rs b/lez/storage/src/indexer/read_once.rs
index 6e79adc4..777bbf58 100644
--- a/lez/storage/src/indexer/read_once.rs
+++ b/lez/storage/src/indexer/read_once.rs
@@ -3,8 +3,9 @@ use crate::{
     DBIO as _,
     cells::shared_cells::{BlockCell, FirstBlockCell, FirstBlockSetCell, LastBlockCell},
     indexer::indexer_cells::{
-        AccNumTxCell, BlockHashToBlockIdMapCell, BreakpointCellOwned, LastBreakpointIdCell,
-        LastObservedL1LibHeaderCell, TxHashToBlockIdMapCell, ZoneSdkIndexerCursorCellOwned,
+        AccNumTxCell, BlockHashToBlockIdMapCell, BreakpointCellOwned, ChainBreakerCellOwned,
+        LastBreakpointIdCell, LastObservedL1LibHeaderCell, TxHashToBlockIdMapCell,
+        ZoneSdkIndexerCursorCellOwned,
     },
 };
 
@@ -73,4 +74,10 @@ impl RocksDBIO {
             .get_opt::<ZoneSdkIndexerCursorCellOwned>(())?
             .map(|cell| cell.0))
     }
+
+    pub fn get_chain_breaker_bytes(&self) -> DbResult<Option<Vec<u8>>> {
+        Ok(self
+            .get_opt::<ChainBreakerCellOwned>(())?
+            .map(|cell| cell.0))
+    }
 }
diff --git a/lez/storage/src/indexer/write_non_atomic.rs b/lez/storage/src/indexer/write_non_atomic.rs
index 7ddab1dd..555c5efb 100644
--- a/lez/storage/src/indexer/write_non_atomic.rs
+++ b/lez/storage/src/indexer/write_non_atomic.rs
@@ -3,7 +3,7 @@ use crate::{
     DBIO as _,
     cells::shared_cells::{FirstBlockSetCell, LastBlockCell},
     indexer::indexer_cells::{
-        BreakpointCellRef, LastBreakpointIdCell, LastObservedL1LibHeaderCell,
+        BreakpointCellRef, ChainBreakerCellRef, LastBreakpointIdCell, LastObservedL1LibHeaderCell,
         ZoneSdkIndexerCursorCellRef,
     },
 };
@@ -35,6 +35,10 @@ impl RocksDBIO {
         self.put(&ZoneSdkIndexerCursorCellRef(bytes), ())
     }
 
+    pub fn put_chain_breaker_bytes(&self, bytes: &[u8]) -> DbResult<()> {
+        self.put(&ChainBreakerCellRef(bytes), ())
+    }
+
     // State
 
     pub fn put_breakpoint(&self, br_id: u64, breakpoint: &V03State) -> DbResult<()> {