tests.rs

// SPDX-FileCopyrightText: Copyright (c) 2024-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
// SPDX-License-Identifier: Apache-2.0

use std::sync::Arc;
use std::time::{Duration, Instant};

use rstest::rstest;
use rstest_reuse::{self, *};
use tokio::time;
use tokio_util::sync::CancellationToken;

use super::concurrent_radix_tree::ConcurrentRadixTree;
use super::concurrent_radix_tree_compressed::ConcurrentRadixTreeCompressed;
use super::positional::PositionalIndexer;
use super::*;
use crate::protocols::*;
use crate::test_utils::{remove_event, router_event, stored_blocks_with_sequence_hashes};

// ============================================================================
// Helper functions
// ============================================================================

/// Create a store event with proper sequence hashes computed from local hashes.
fn make_store_event(worker_id: u64, local_hashes: &[u64]) -> RouterEvent {
    make_store_event_with_dp_rank(worker_id, local_hashes, 0)
}

/// Create a store event with a specific dp_rank.
fn make_store_event_with_dp_rank(
    worker_id: u64,
    local_hashes: &[u64],
    dp_rank: u32,
) -> RouterEvent {
    make_store_event_full(worker_id, local_hashes, dp_rank, None)
}

/// Create a store event with parent hash for continuation sequences.
/// `prefix_hashes` are the hashes of the prefix (to compute parent_hash).
/// `local_hashes` are the new blocks being stored.
fn make_store_event_with_parent(
    worker_id: u64,
    prefix_hashes: &[u64],
    local_hashes: &[u64],
) -> RouterEvent {
    // Compute the parent hash from the prefix
    let prefix_block_hashes: Vec<LocalBlockHash> =
        prefix_hashes.iter().map(|&h| LocalBlockHash(h)).collect();
    let prefix_seq_hashes = compute_seq_hash_for_block(&prefix_block_hashes);
    let parent_hash = prefix_seq_hashes
        .last()
        .map(|&h| ExternalSequenceBlockHash(h));

    // Compute the full sequence including prefix for proper seq_hash calculation
    let full_hashes: Vec<u64> = prefix_hashes
        .iter()
        .chain(local_hashes.iter())
        .copied()
        .collect();
    let full_block_hashes: Vec<LocalBlockHash> =
        full_hashes.iter().map(|&h| LocalBlockHash(h)).collect();
    let full_seq_hashes = compute_seq_hash_for_block(&full_block_hashes);

    // Only include the new blocks (skip prefix)
    let new_block_hashes: Vec<LocalBlockHash> =
        local_hashes.iter().map(|&h| LocalBlockHash(h)).collect();
    let new_seq_hashes = &full_seq_hashes[prefix_hashes.len()..];

    router_event(
        worker_id,
        0,
        0,
        KvCacheEventData::Stored(KvCacheStoreData {
            parent_hash,
            blocks: stored_blocks_with_sequence_hashes(&new_block_hashes, new_seq_hashes),
        }),
    )
}

/// Create a store event with all options.
fn make_store_event_full(
    worker_id: u64,
    local_hashes: &[u64],
    dp_rank: u32,
    parent_hash: Option<ExternalSequenceBlockHash>,
) -> RouterEvent {
    let local_block_hashes: Vec<LocalBlockHash> =
        local_hashes.iter().map(|&h| LocalBlockHash(h)).collect();
    let seq_hashes = compute_seq_hash_for_block(&local_block_hashes);

    router_event(
        worker_id,
        0,
        dp_rank,
        KvCacheEventData::Stored(KvCacheStoreData {
            parent_hash,
            blocks: stored_blocks_with_sequence_hashes(&local_block_hashes, &seq_hashes),
        }),
    )
}

/// Create a remove event for blocks with given local hashes.
fn make_remove_event(worker_id: u64, local_hashes: &[u64]) -> RouterEvent {
    make_remove_event_with_dp_rank(worker_id, local_hashes, 0)
}

/// Create a remove event with a specific dp_rank.
fn make_remove_event_with_dp_rank(
    worker_id: u64,
    local_hashes: &[u64],
    dp_rank: u32,
) -> RouterEvent {
    let local_block_hashes: Vec<LocalBlockHash> =
        local_hashes.iter().map(|&h| LocalBlockHash(h)).collect();
    let seq_hashes = compute_seq_hash_for_block(&local_block_hashes);

    remove_event(
        worker_id,
        0,
        dp_rank,
        seq_hashes
            .iter()
            .map(|&h| ExternalSequenceBlockHash(h))
            .collect(),
    )
}

/// Create a remove event with parent hash for continuation sequences.
/// `prefix_hashes` are the hashes of the prefix (to compute parent_hash and full seq context).
/// `local_hashes` are the blocks being removed.
fn make_remove_event_with_parent(
    worker_id: u64,
    prefix_hashes: &[u64],
    local_hashes: &[u64],
) -> RouterEvent {
    let full_hashes: Vec<u64> = prefix_hashes
        .iter()
        .chain(local_hashes.iter())
        .copied()
        .collect();
    let full_block_hashes: Vec<LocalBlockHash> =
        full_hashes.iter().map(|&h| LocalBlockHash(h)).collect();
    let full_seq_hashes = compute_seq_hash_for_block(&full_block_hashes);

    let suffix_seq_hashes = &full_seq_hashes[prefix_hashes.len()..];

    remove_event(
        worker_id,
        0,
        0,
        suffix_seq_hashes
            .iter()
            .map(|&h| ExternalSequenceBlockHash(h))
            .collect(),
    )
}

/// Snapshot the tree state for deterministic comparison.
/// Dumps all events, zeros out `event_id`, and sorts by `(worker_id, dp_rank, block_hash)`.
async fn snapshot_tree(index: &dyn KvIndexerInterface) -> Vec<RouterEvent> {
    let mut events = index.dump_events().await.unwrap();
    for ev in &mut events {
        ev.event.event_id = 0;
    }
    events.sort_by(|a, b| {
        a.worker_id.cmp(&b.worker_id).then_with(|| {
            a.event.dp_rank.cmp(&b.event.dp_rank).then_with(|| {
                let hash_a = match &a.event.data {
                    KvCacheEventData::Stored(s) => {
                        s.blocks.first().map(|b| b.block_hash.0).unwrap_or(0)
                    }
                    KvCacheEventData::Removed(r) => {
                        r.block_hashes.first().map(|h| h.0).unwrap_or(0)
                    }
                    KvCacheEventData::Cleared => 0,
                };
                let hash_b = match &b.event.data {
                    KvCacheEventData::Stored(s) => {
                        s.blocks.first().map(|b| b.block_hash.0).unwrap_or(0)
                    }
                    KvCacheEventData::Removed(r) => {
                        r.block_hashes.first().map(|h| h.0).unwrap_or(0)
                    }
                    KvCacheEventData::Cleared => 0,
                };
                hash_a.cmp(&hash_b)
            })
        })
    });
    events
}

/// Create a clear event for a worker.
fn make_clear_event(worker_id: u64) -> RouterEvent {
    make_clear_event_with_dp_rank(worker_id, 0)
}

/// Create a clear event with a specific dp_rank.
fn make_clear_event_with_dp_rank(worker_id: u64, dp_rank: u32) -> RouterEvent {
    router_event(worker_id, 0, dp_rank, KvCacheEventData::Cleared)
}

// ============================================================================
// KvIndexerInterface tests - parametrized over all implementations
// ============================================================================

#[template]
#[rstest]
fn indexer_template(
    #[values("single", "sharded", "flat", "concurrent", "concurrent_compressed")] variant: &str,
) {
}

#[template]
#[rstest]
fn tree_size_indexer_template(
    #[values("single", "sharded", "concurrent", "concurrent_compressed")] variant: &str,
) {
}

fn make_indexer(variant: &str) -> Box<dyn KvIndexerInterface> {
    let token = CancellationToken::new();
    let metrics = Arc::new(KvIndexerMetrics::new_unregistered());
    let kv_block_size = 32;

    match variant {
        "single" => Box::new(KvIndexer::new(token, kv_block_size, metrics)),
        "sharded" => Box::new(KvIndexerSharded::new(token, 4, kv_block_size, metrics)),
        "flat" => Box::new(ThreadPoolIndexer::new(
            PositionalIndexer::new(32),
            4,
            kv_block_size,
        )),
        "concurrent" => Box::new(ThreadPoolIndexer::new(
            ConcurrentRadixTree::new(),
            4,
            kv_block_size,
        )),
        "concurrent_compressed" => Box::new(ThreadPoolIndexer::new(
            ConcurrentRadixTreeCompressed::new(),
            4,
            kv_block_size,
        )),
        _ => panic!("Unknown variant: {}", variant),
    }
}

/// Ensure queued indexer work is drained, then give a short settle window.
/// This is intentionally conservative for tests that assert immediately
/// after asynchronous event ingestion.
async fn flush_and_settle(index: &dyn KvIndexerInterface) {
    index.flush().await;
    tokio::time::sleep(Duration::from_millis(100)).await;
}

async fn query_scores(index: &dyn KvIndexerInterface, query: &[u64]) -> OverlapScores {
    index
        .find_matches(query.iter().copied().map(LocalBlockHash).collect())
        .await
        .unwrap()
}

async fn assert_score(
    index: &dyn KvIndexerInterface,
    query: &[u64],
    worker: WorkerWithDpRank,
    expected_score: u32,
) {
    let scores = query_scores(index, query).await;
    assert_eq!(scores.scores.get(&worker), Some(&expected_score));
}

async fn assert_query_score_and_tree_size(
    index: &dyn KvIndexerInterface,
    query: &[u64],
    worker: WorkerWithDpRank,
    expected_score: u32,
    expected_tree_size: usize,
) {
    let scores = query_scores(index, query).await;
    assert_eq!(scores.scores.get(&worker), Some(&expected_score));
    assert_eq!(scores.tree_sizes.get(&worker), Some(&expected_tree_size));
}

async fn assert_no_scores(index: &dyn KvIndexerInterface, query: &[u64]) {
    let scores = query_scores(index, query).await;
    assert!(scores.scores.is_empty());
}

async fn assert_exact_scores(
    index: &dyn KvIndexerInterface,
    query: &[u64],
    expected_scores: &[(WorkerWithDpRank, u32)],
) {
    let scores = query_scores(index, query).await;
    assert_eq!(scores.scores.len(), expected_scores.len());
    for (worker, expected_score) in expected_scores {
        assert_eq!(scores.scores.get(worker), Some(expected_score));
    }
}

mod interface_tests {
    use super::*;
    use rstest_reuse::apply;

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_store_and_find(variant: &str) {
        let index = make_indexer(variant);

        // Store a sequence for worker 0
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        flush_and_settle(index.as_ref()).await;

        assert_score(index.as_ref(), &[1, 2, 3], WorkerWithDpRank::new(0, 0), 3).await;
    }

    #[tokio::test]
    #[apply(tree_size_indexer_template)]
    async fn test_tree_size_accounting_stays_stable(variant: &str) {
        let index = make_indexer(variant);
        let worker = WorkerWithDpRank::new(0, 0);
        let prefix_event = make_store_event(0, &[1, 2, 3]);
        let continuation_event = make_store_event_with_parent(0, &[1, 2, 3], &[4, 5]);
        let continuation_remove = make_remove_event_with_parent(0, &[1, 2, 3], &[4, 5]);
        let prefix_remove = make_remove_event(0, &[1, 2, 3]);

        // TODO: The radix-family implementations still have a broader tree-size
        // accounting gap after mid-chain removes because descendant lookup entries
        // are cleaned up lazily. That means "store -> partial remove -> restore
        // continuation" can still miscount restored coverage in single, sharded,
        // concurrent, and concurrent_compressed. This test is intentionally scoped
        // to duplicate store/remove replay, which was the concrete compressed-tree
        // regression fixed on this branch.

        index.apply_event(prefix_event.clone()).await;
        flush_and_settle(index.as_ref()).await;

        assert_query_score_and_tree_size(index.as_ref(), &[1, 2, 3], worker, 3, 3).await;
        let prefix_snapshot = snapshot_tree(index.as_ref()).await;

        index.apply_event(prefix_event).await;
        flush_and_settle(index.as_ref()).await;

        assert_eq!(
            prefix_snapshot,
            snapshot_tree(index.as_ref()).await,
            "replaying the same store event should not change the tree structure"
        );
        assert_query_score_and_tree_size(index.as_ref(), &[1, 2, 3], worker, 3, 3).await;

        index.apply_event(continuation_event.clone()).await;
        flush_and_settle(index.as_ref()).await;

        assert_query_score_and_tree_size(index.as_ref(), &[1, 2, 3, 4, 5], worker, 5, 5).await;
        let full_snapshot = snapshot_tree(index.as_ref()).await;

        index.apply_event(continuation_event).await;
        flush_and_settle(index.as_ref()).await;

        assert_eq!(
            full_snapshot,
            snapshot_tree(index.as_ref()).await,
            "replaying the same continuation store should not change the tree structure"
        );
        assert_query_score_and_tree_size(index.as_ref(), &[1, 2, 3, 4, 5], worker, 5, 5).await;

        index.apply_event(continuation_remove.clone()).await;
        flush_and_settle(index.as_ref()).await;

        assert_query_score_and_tree_size(index.as_ref(), &[1, 2, 3, 4, 5], worker, 3, 3).await;
        let trimmed_snapshot = snapshot_tree(index.as_ref()).await;

        index.apply_event(continuation_remove).await;
        flush_and_settle(index.as_ref()).await;

        assert_eq!(
            trimmed_snapshot,
            snapshot_tree(index.as_ref()).await,
            "replaying the same remove event should not change the tree structure"
        );
        assert_query_score_and_tree_size(index.as_ref(), &[1, 2, 3, 4, 5], worker, 3, 3).await;

        index.apply_event(prefix_remove.clone()).await;
        flush_and_settle(index.as_ref()).await;

        let empty_scores = index
            .find_matches(vec![
                LocalBlockHash(1),
                LocalBlockHash(2),
                LocalBlockHash(3),
                LocalBlockHash(4),
                LocalBlockHash(5),
            ])
            .await
            .unwrap();
        assert!(empty_scores.scores.is_empty());
        assert!(snapshot_tree(index.as_ref()).await.is_empty());

        index.apply_event(prefix_remove).await;
        flush_and_settle(index.as_ref()).await;

        let duplicate_empty_scores = index
            .find_matches(vec![
                LocalBlockHash(1),
                LocalBlockHash(2),
                LocalBlockHash(3),
                LocalBlockHash(4),
                LocalBlockHash(5),
            ])
            .await
            .unwrap();
        assert!(duplicate_empty_scores.scores.is_empty());
        assert!(snapshot_tree(index.as_ref()).await.is_empty());
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_partial_match(variant: &str) {
        let index = make_indexer(variant);

        // Store [1, 2, 3] for worker 0
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        flush_and_settle(index.as_ref()).await;

        assert_score(index.as_ref(), &[1, 2, 999], WorkerWithDpRank::new(0, 0), 2).await;
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_remove(variant: &str) {
        let index = make_indexer(variant);

        // Store sequence for worker 0
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        // Remove all blocks
        index.apply_event(make_remove_event(0, &[1, 2, 3])).await;

        flush_and_settle(index.as_ref()).await;

        assert_no_scores(index.as_ref(), &[1, 2, 3]).await;
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_multiple_workers_shared_prefix(variant: &str) {
        let index = make_indexer(variant);

        // Worker 0 has [1, 2], Worker 1 has [1, 3]
        // Since sequence hashes are cumulative, [1] has same hash for both,
        // but [1, 2] and [1, 3] have different hashes.
        index.apply_event(make_store_event(0, &[1, 2])).await;
        index.apply_event(make_store_event(1, &[1, 3])).await;

        flush_and_settle(index.as_ref()).await;

        assert_exact_scores(
            index.as_ref(),
            &[1],
            &[
                (WorkerWithDpRank::new(0, 0), 1),
                (WorkerWithDpRank::new(1, 0), 1),
            ],
        )
        .await;

        assert_exact_scores(
            index.as_ref(),
            &[1, 2],
            &[
                (WorkerWithDpRank::new(0, 0), 2),
                (WorkerWithDpRank::new(1, 0), 1),
            ],
        )
        .await;
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_remove_worker(variant: &str) {
        let index = make_indexer(variant);

        index.apply_event(make_store_event(0, &[1, 2, 3])).await;
        index.apply_event(make_store_event(1, &[1, 2, 3])).await;

        // Allow time for async event processing
        flush_and_settle(index.as_ref()).await;

        index.remove_worker(0).await;

        // Allow time for async remove_worker processing
        flush_and_settle(index.as_ref()).await;

        assert_exact_scores(
            index.as_ref(),
            &[1, 2, 3],
            &[(WorkerWithDpRank::new(1, 0), 3)],
        )
        .await;
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_large_stores(variant: &str) {
        let index = make_indexer(variant);

        // Test sequences of increasing sizes
        for i in 0..10u64 {
            let len = 1 << i; // 1, 2, 4, 8, ..., 512
            let worker_id = i;
            let sequence: Vec<u64> = (1..=len).map(|x| x + (i * 10000)).collect();
            index
                .apply_event(make_store_event(worker_id, &sequence))
                .await;
        }

        flush_and_settle(index.as_ref()).await;

        // Verify we can find matches for the last stored sequence
        let last_seq: Vec<LocalBlockHash> = (1..=512u64)
            .map(|x| LocalBlockHash(x + (9 * 10000)))
            .collect();
        let scores = index.find_matches(last_seq).await.unwrap();
        assert!(!scores.scores.is_empty());
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_dump_and_restore(variant: &str) {
        let index = make_indexer(variant);

        // Store some data
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;
        index.apply_event(make_store_event(1, &[1, 2, 4])).await;

        // Allow background worker threads to process events.
        flush_and_settle(index.as_ref()).await;

        // Dump the tree as events and replay into a new index
        let events = index.dump_events().await.unwrap();
        assert!(!events.is_empty());

        let restored = make_indexer(variant);
        for event in events {
            restored.apply_event(event).await;
        }

        flush_and_settle(restored.as_ref()).await;

        assert_eq!(
            snapshot_tree(index.as_ref()).await,
            snapshot_tree(restored.as_ref()).await
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_clear_all_blocks(variant: &str) {
        let index = make_indexer(variant);

        // Store some data for two workers
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;
        index.apply_event(make_store_event(1, &[1, 2, 3])).await;

        // Clear worker 0's blocks using the Cleared event
        index.apply_event(make_clear_event(0)).await;

        flush_and_settle(index.as_ref()).await;

        // Worker 0's blocks should be gone, worker 1's remain
        let scores = index
            .find_matches(vec![
                LocalBlockHash(1),
                LocalBlockHash(2),
                LocalBlockHash(3),
            ])
            .await
            .unwrap();
        assert_eq!(scores.scores.len(), 1);
        assert!(scores.scores.contains_key(&WorkerWithDpRank::new(1, 0)));
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_empty_query(variant: &str) {
        let index = make_indexer(variant);

        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        flush_and_settle(index.as_ref()).await;

        assert_no_scores(index.as_ref(), &[]).await;
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_miss_query(variant: &str) {
        let index = make_indexer(variant);

        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        flush_and_settle(index.as_ref()).await;

        assert_no_scores(index.as_ref(), &[999, 998]).await;
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_shutdown(variant: &str) {
        let index = make_indexer(variant);
        index.shutdown();
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_shutdown_idempotent(variant: &str) {
        let index = make_indexer(variant);
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;
        flush_and_settle(index.as_ref()).await;
        index.shutdown();
        index.shutdown();
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_find_matches_for_request(variant: &str) {
        let index = make_indexer(variant);

        // Empty index should return no matches
        let tokens = vec![1, 2, 3, 4];
        let scores = index
            .find_matches_for_request(&tokens, None, None)
            .await
            .unwrap();
        assert!(scores.scores.is_empty());

        // Store some data and verify we can find it via tokens
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        // Allow time for async processing
        flush_and_settle(index.as_ref()).await;

        // Note: find_matches_for_request computes block hashes from tokens,
        // so we need tokens that hash to the same LocalBlockHash values.
        // For this test, we just verify the method works without error.
        let scores = index
            .find_matches_for_request(&tokens, None, None)
            .await
            .unwrap();
        // The tokens [1,2,3,4] won't match our stored [1,2,3] local hashes
        // because find_matches_for_request computes different hashes from raw tokens
        assert!(scores.scores.is_empty() || !scores.scores.is_empty());
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_process_routing_decision(variant: &str) {
        let index = make_indexer(variant);

        // Create tokens with hashes
        let tokens = vec![1u32, 2, 3, 4, 5, 6, 7, 8];
        let mut tokens_with_hashes = TokensWithHashes::new(tokens, 32);

        let worker = WorkerWithDpRank::new(0, 0);

        // Process routing decision - should not error
        let result = index
            .process_routing_decision_for_request(&mut tokens_with_hashes, worker)
            .await;
        assert!(result.is_ok());
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_parent_hash_chains(variant: &str) {
        let index = make_indexer(variant);

        // Store initial sequence [1, 2, 3]
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        // Store continuation [4, 5] with parent pointing to block 3
        index
            .apply_event(make_store_event_with_parent(0, &[1, 2, 3], &[4, 5]))
            .await;

        flush_and_settle(index.as_ref()).await;

        // Query for full sequence [1, 2, 3, 4, 5] should match all 5 blocks
        assert_score(
            index.as_ref(),
            &[1, 2, 3, 4, 5],
            WorkerWithDpRank::new(0, 0),
            5,
        )
        .await;

        // Query for just [1, 2, 3] should match 3 blocks
        assert_score(index.as_ref(), &[1, 2, 3], WorkerWithDpRank::new(0, 0), 3).await;
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_multiple_dp_ranks(variant: &str) {
        let index = make_indexer(variant);

        // Same worker_id but different dp_ranks should be tracked separately
        index
            .apply_event(make_store_event_with_dp_rank(0, &[1, 2, 3], 0))
            .await;
        index
            .apply_event(make_store_event_with_dp_rank(0, &[1, 2, 3], 1))
            .await;
        index
            .apply_event(make_store_event_with_dp_rank(0, &[1, 2, 3], 2))
            .await;

        flush_and_settle(index.as_ref()).await;

        // Query should return all 3 dp_ranks as separate entries
        let seq: Vec<LocalBlockHash> = (1..=3).map(LocalBlockHash).collect();
        let scores = index.find_matches(seq).await.unwrap();

        assert_eq!(scores.scores.len(), 3);
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 3);
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 1)).unwrap(), 3);
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 2)).unwrap(), 3);
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_partial_block_removal(variant: &str) {
        let index = make_indexer(variant);

        // Store [1, 2, 3]
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        flush_and_settle(index.as_ref()).await;

        // Verify all 3 blocks match
        let seq: Vec<LocalBlockHash> = (1..=3).map(LocalBlockHash).collect();
        let scores = index.find_matches(seq.clone()).await.unwrap();
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 3);

        // Remove only the last block (block 3)
        // To do this correctly, we need to compute the seq_hash for block 3 specifically,
        // which requires the full sequence context [1,2,3].
        let full_hashes: Vec<LocalBlockHash> = (1..=3).map(LocalBlockHash).collect();
        let seq_hashes = compute_seq_hash_for_block(&full_hashes);
        let block_3_seq_hash = ExternalSequenceBlockHash(seq_hashes[2]); // Last block's hash

        let remove_event = remove_event(0, 0, 0, vec![block_3_seq_hash]);
        index.apply_event(remove_event).await;

        flush_and_settle(index.as_ref()).await;

        // Query [1, 2, 3] - should only match 2 blocks now (block 3 is removed)
        let scores = index.find_matches(seq).await.unwrap();
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 2);

        // Query [1, 2] - should still match 2 blocks
        let partial_seq: Vec<LocalBlockHash> = (1..=2).map(LocalBlockHash).collect();
        let scores = index.find_matches(partial_seq).await.unwrap();
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 2);
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_remove_mid_chain_block(variant: &str) {
        // TODO: positional indexer has no parent-child structure, so mid-chain removal
        // doesn't invalidate later positions — jump search skips over the gap and over-counts.
        if variant == "flat" {
            return;
        }

        let index = make_indexer(variant);

        // Store [1, 2, 3, 4, 5]
        index
            .apply_event(make_store_event(0, &[1, 2, 3, 4, 5]))
            .await;

        flush_and_settle(index.as_ref()).await;

        // Verify all 5 blocks match
        let seq: Vec<LocalBlockHash> = (1..=5).map(LocalBlockHash).collect();
        let scores = index.find_matches(seq.clone()).await.unwrap();
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 5);

        // Remove only block 3 (index 2) — the middle of the chain
        let full_hashes: Vec<LocalBlockHash> = (1..=5).map(LocalBlockHash).collect();
        let seq_hashes = compute_seq_hash_for_block(&full_hashes);
        let block_3_seq_hash = ExternalSequenceBlockHash(seq_hashes[2]);

        let remove_event = remove_event(0, 0, 0, vec![block_3_seq_hash]);
        index.apply_event(remove_event).await;

        flush_and_settle(index.as_ref()).await;

        // Query [1, 2, 3, 4, 5] — only first 2 positions reachable (block 3 removed, orphaning 4 & 5)
        let scores = index.find_matches(seq.clone()).await.unwrap();
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 2);

        // Query [1, 2] — prefix before the gap is still intact
        let prefix_seq: Vec<LocalBlockHash> = (1..=2).map(LocalBlockHash).collect();
        let scores = index.find_matches(prefix_seq).await.unwrap();
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 2);

        // Re-store block 3 as a continuation of [1, 2]
        index
            .apply_event(make_store_event_with_parent(0, &[1, 2], &[3]))
            .await;

        flush_and_settle(index.as_ref()).await;

        // Query [1, 2, 3, 4, 5] — block 3 is back but 4 & 5 were orphaned, so score = 3
        let scores = index.find_matches(seq).await.unwrap();
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 3);
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_remove_nonexistent_worker(variant: &str) {
        let index = make_indexer(variant);

        // Store data for worker 0
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        flush_and_settle(index.as_ref()).await;

        // Remove non-existent worker 999 - should not error or affect worker 0
        index.remove_worker(999).await;

        // Allow time for async processing
        flush_and_settle(index.as_ref()).await;

        // Worker 0's data should still be there
        let seq: Vec<LocalBlockHash> = (1..=3).map(LocalBlockHash).collect();
        let scores = index.find_matches(seq).await.unwrap();
        assert_eq!(scores.scores.len(), 1);
        assert!(scores.scores.contains_key(&WorkerWithDpRank::new(0, 0)));
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_remove_nonexistent_blocks(variant: &str) {
        let index = make_indexer(variant);

        // Store [1, 2, 3]
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        // Try to remove blocks [999, 998] that don't exist - should not error
        index.apply_event(make_remove_event(0, &[999, 998])).await;

        flush_and_settle(index.as_ref()).await;

        // Original data should still be there
        let seq: Vec<LocalBlockHash> = (1..=3).map(LocalBlockHash).collect();
        let scores = index.find_matches(seq).await.unwrap();
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 3);
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_clear_then_reuse(variant: &str) {
        let index = make_indexer(variant);

        // Store initial data
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        // Clear the worker
        index.apply_event(make_clear_event(0)).await;

        flush_and_settle(index.as_ref()).await;

        // Verify data is gone
        let seq: Vec<LocalBlockHash> = (1..=3).map(LocalBlockHash).collect();
        let scores = index.find_matches(seq.clone()).await.unwrap();
        assert!(scores.scores.is_empty());

        // Store new data for the same worker
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;

        flush_and_settle(index.as_ref()).await;

        // Verify new data is accessible
        let scores = index.find_matches(seq).await.unwrap();
        assert_eq!(scores.scores.len(), 1);
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 3);
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_multiple_sequences_per_worker(variant: &str) {
        let index = make_indexer(variant);

        // Store two disjoint sequences for the same worker
        // Sequence 1: [1, 2, 3]
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;
        // Sequence 2: [100, 101, 102] (completely different, no parent)
        index
            .apply_event(make_store_event(0, &[100, 101, 102]))
            .await;

        flush_and_settle(index.as_ref()).await;

        // Query first sequence
        let seq1: Vec<LocalBlockHash> = (1..=3).map(LocalBlockHash).collect();
        let scores = index.find_matches(seq1).await.unwrap();
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 3);

        // Query second sequence
        let seq2: Vec<LocalBlockHash> = (100..=102).map(LocalBlockHash).collect();
        let scores = index.find_matches(seq2).await.unwrap();
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 3);

        // Query a mix that doesn't exist as a sequence - should only match first block
        let mixed: Vec<LocalBlockHash> = vec![LocalBlockHash(1), LocalBlockHash(100)];
        let scores = index.find_matches(mixed).await.unwrap();
        // Only block 1 matches because [1, 100] is not a valid prefix
        assert_eq!(*scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(), 1);
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_clear_clears_all_dp_ranks(variant: &str) {
        let index = make_indexer(variant);

        // Store same sequence for different dp_ranks
        index
            .apply_event(make_store_event_with_dp_rank(0, &[1, 2, 3], 0))
            .await;
        index
            .apply_event(make_store_event_with_dp_rank(0, &[1, 2, 3], 1))
            .await;

        flush_and_settle(index.as_ref()).await;

        // Verify both dp_ranks are present
        let seq: Vec<LocalBlockHash> = (1..=3).map(LocalBlockHash).collect();
        let scores = index.find_matches(seq.clone()).await.unwrap();
        assert_eq!(scores.scores.len(), 2);

        // Clear event clears ALL blocks for the worker_id, regardless of dp_rank
        index.apply_event(make_clear_event_with_dp_rank(0, 0)).await;

        flush_and_settle(index.as_ref()).await;

        // Both dp_ranks should be cleared
        let scores = index.find_matches(seq).await.unwrap();
        assert!(
            scores.scores.is_empty(),
            "Cleared event should clear all dp_ranks for a worker"
        );
    }
}

// ============================================================================
// LoRA isolation tests
// ============================================================================

mod lora_tests {
    use super::*;
    use rstest_reuse::apply;

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_lora_and_base_model_blocks_do_not_conflict(variant: &str) {
        let index = make_indexer(variant);
        let kv_block_size: u32 = 32;

        // Same token sequence for both base model and LoRA adapter
        let tokens: Vec<u32> = (0..kv_block_size * 3).collect();

        let base_hashes =
            compute_block_hash_for_seq(&tokens, kv_block_size, BlockHashOptions::default());
        let lora_hashes = compute_block_hash_for_seq(
            &tokens,
            kv_block_size,
            BlockHashOptions {
                lora_name: Some("my-adapter"),
                ..Default::default()
            },
        );

        // Hashes must differ despite identical tokens
        assert_ne!(
            base_hashes, lora_hashes,
            "Base and LoRA hashes must differ for the same tokens"
        );

        let base_seq = compute_seq_hash_for_block(&base_hashes);
        let lora_seq = compute_seq_hash_for_block(&lora_hashes);

        // Store base-model blocks on worker 0
        let base_event = router_event(
            0,
            0,
            0,
            KvCacheEventData::Stored(KvCacheStoreData {
                parent_hash: None,
                blocks: stored_blocks_with_sequence_hashes(&base_hashes, &base_seq),
            }),
        );
        index.apply_event(base_event).await;

        // Store LoRA blocks on worker 1
        let lora_event = router_event(
            1,
            0,
            0,
            KvCacheEventData::Stored(KvCacheStoreData {
                parent_hash: None,
                blocks: stored_blocks_with_sequence_hashes(&lora_hashes, &lora_seq),
            }),
        );
        index.apply_event(lora_event).await;

        flush_and_settle(index.as_ref()).await;

        // Query with base-model hashes → only worker 0
        let base_scores = index.find_matches(base_hashes.clone()).await.unwrap();
        assert_eq!(
            base_scores.scores.len(),
            1,
            "Only base-model worker should match"
        );
        assert_eq!(
            *base_scores
                .scores
                .get(&WorkerWithDpRank::new(0, 0))
                .unwrap(),
            3
        );

        // Query with LoRA hashes → only worker 1
        let lora_scores = index.find_matches(lora_hashes.clone()).await.unwrap();
        assert_eq!(lora_scores.scores.len(), 1, "Only LoRA worker should match");
        assert_eq!(
            *lora_scores
                .scores
                .get(&WorkerWithDpRank::new(1, 0))
                .unwrap(),
            3
        );
    }

    /// Reproduces the "block_hash mismatch: sequence hashes should be uniform
    /// across workers" warning seen when the same prompt is sent to both a base
    /// model worker and a LoRA worker.
    ///
    /// On main (without LoRA-aware hashing), both workers compute the same
    /// LocalBlockHash for identical tokens.  But vLLM's engine includes the
    /// adapter in its rolling ExternalSequenceBlockHash, so the radix tree
    /// sees conflicting sequence hashes at the same tree node.
    ///
    /// With LoRA-aware hashing, compute_block_hash_for_seq produces distinct
    /// LocalBlockHash values for different adapters, so the blocks land on
    /// separate tree paths and no mismatch occurs.
    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_lora_base_same_tokens_no_seq_hash_mismatch(variant: &str) {
        let index = make_indexer(variant);
        let kv_block_size: u32 = 32;

        let tokens: Vec<u32> = (0..kv_block_size * 3).collect();

        // With LoRA-aware hashing, base and adapter produce different LocalBlockHash
        let base_local =
            compute_block_hash_for_seq(&tokens, kv_block_size, BlockHashOptions::default());
        let lora_local = compute_block_hash_for_seq(
            &tokens,
            kv_block_size,
            BlockHashOptions {
                lora_name: Some("my-adapter"),
                ..Default::default()
            },
        );

        assert_ne!(
            base_local, lora_local,
            "LoRA-aware hashing must produce different LocalBlockHash values"
        );

        // Simulate what vLLM does: same tokens, different rolling seq hashes
        // because the engine accounts for the adapter internally.
        let base_seq = compute_seq_hash_for_block(&base_local);
        let lora_seq = compute_seq_hash_for_block(&lora_local);

        // Worker 0: base model
        index
            .apply_event(router_event(
                0,
                0,
                0,
                KvCacheEventData::Stored(KvCacheStoreData {
                    parent_hash: None,
                    blocks: stored_blocks_with_sequence_hashes(&base_local, &base_seq),
                }),
            ))
            .await;

        // Worker 1: LoRA adapter — different LocalBlockHash, so this goes to
        // a separate tree path instead of colliding with worker 0's node.
        index
            .apply_event(router_event(
                1,
                0,
                0,
                KvCacheEventData::Stored(KvCacheStoreData {
                    parent_hash: None,
                    blocks: stored_blocks_with_sequence_hashes(&lora_local, &lora_seq),
                }),
            ))
            .await;

        flush_and_settle(index.as_ref()).await;

        // Base query finds only worker 0
        let base_scores = index.find_matches(base_local.clone()).await.unwrap();
        assert_eq!(base_scores.scores.len(), 1);
        assert_eq!(
            *base_scores
                .scores
                .get(&WorkerWithDpRank::new(0, 0))
                .unwrap(),
            3
        );

        // LoRA query finds only worker 1
        let lora_scores = index.find_matches(lora_local.clone()).await.unwrap();
        assert_eq!(lora_scores.scores.len(), 1);
        assert_eq!(
            *lora_scores
                .scores
                .get(&WorkerWithDpRank::new(1, 0))
                .unwrap(),
            3
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_different_lora_adapters_do_not_conflict(variant: &str) {
        let index = make_indexer(variant);
        let kv_block_size: u32 = 32;

        let tokens: Vec<u32> = (0..kv_block_size * 2).collect();

        let hashes_a = compute_block_hash_for_seq(
            &tokens,
            kv_block_size,
            BlockHashOptions {
                lora_name: Some("adapter-a"),
                ..Default::default()
            },
        );
        let hashes_b = compute_block_hash_for_seq(
            &tokens,
            kv_block_size,
            BlockHashOptions {
                lora_name: Some("adapter-b"),
                ..Default::default()
            },
        );

        assert_ne!(
            hashes_a, hashes_b,
            "Different adapters must produce different hashes"
        );

        let seq_a = compute_seq_hash_for_block(&hashes_a);
        let seq_b = compute_seq_hash_for_block(&hashes_b);

        // Store adapter-a blocks on worker 0
        index
            .apply_event(router_event(
                0,
                0,
                0,
                KvCacheEventData::Stored(KvCacheStoreData {
                    parent_hash: None,
                    blocks: stored_blocks_with_sequence_hashes(&hashes_a, &seq_a),
                }),
            ))
            .await;

        // Store adapter-b blocks on worker 1
        index
            .apply_event(router_event(
                1,
                0,
                0,
                KvCacheEventData::Stored(KvCacheStoreData {
                    parent_hash: None,
                    blocks: stored_blocks_with_sequence_hashes(&hashes_b, &seq_b),
                }),
            ))
            .await;

        flush_and_settle(index.as_ref()).await;

        // Query adapter-a → only worker 0
        let scores_a = index.find_matches(hashes_a.clone()).await.unwrap();
        assert_eq!(scores_a.scores.len(), 1);
        assert!(scores_a.scores.contains_key(&WorkerWithDpRank::new(0, 0)));
        assert!(!scores_a.scores.contains_key(&WorkerWithDpRank::new(1, 0)));

        // Query adapter-b → only worker 1
        let scores_b = index.find_matches(hashes_b.clone()).await.unwrap();
        assert_eq!(scores_b.scores.len(), 1);
        assert!(scores_b.scores.contains_key(&WorkerWithDpRank::new(1, 0)));
        assert!(!scores_b.scores.contains_key(&WorkerWithDpRank::new(0, 0)));
    }
}

// ============================================================================
// Long sequence tests - especially important for NestedMap/PositionalIndexer
// ============================================================================

mod long_sequence_tests {
    use super::*;
    use rstest_reuse::apply;

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_single_store(variant: &str) {
        let index = make_indexer(variant);

        // Store a long sequence (128 blocks) in a single event
        let seq_len = 128;
        let sequence: Vec<u64> = (1..=seq_len).collect();
        index.apply_event(make_store_event(0, &sequence)).await;

        flush_and_settle(index.as_ref()).await;

        // Query full sequence - should match all blocks
        let full_query: Vec<LocalBlockHash> = sequence.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(full_query).await.unwrap();
        assert_eq!(scores.scores.len(), 1);
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            seq_len as u32
        );

        // Query prefix (first 64 blocks)
        let prefix_query: Vec<LocalBlockHash> = (1..=64).map(LocalBlockHash).collect();
        let scores = index.find_matches(prefix_query).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            64
        );

        // Query with divergence at position 50
        let mut divergent_query: Vec<LocalBlockHash> = (1..=100).map(LocalBlockHash).collect();
        divergent_query[49] = LocalBlockHash(99999); // Position 49 (0-indexed) diverges
        let scores = index.find_matches(divergent_query).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            49
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_multiple_continuations(variant: &str) {
        let index = make_indexer(variant);

        // Build a long sequence through multiple continuations
        // First store: blocks 1-50
        let first_chunk: Vec<u64> = (1..=50).collect();
        index.apply_event(make_store_event(0, &first_chunk)).await;

        // Second store: blocks 51-100 (continuation of first)
        let second_chunk: Vec<u64> = (51..=100).collect();
        index
            .apply_event(make_store_event_with_parent(0, &first_chunk, &second_chunk))
            .await;

        // Third store: blocks 101-150 (continuation of second)
        let prefix_1_2: Vec<u64> = (1..=100).collect();
        let third_chunk: Vec<u64> = (101..=150).collect();
        index
            .apply_event(make_store_event_with_parent(0, &prefix_1_2, &third_chunk))
            .await;

        flush_and_settle(index.as_ref()).await;

        // Query full sequence - should match all 150 blocks
        let full_query: Vec<LocalBlockHash> = (1..=150).map(LocalBlockHash).collect();
        let scores = index.find_matches(full_query).await.unwrap();
        assert_eq!(scores.scores.len(), 1);
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            150
        );

        // Query crossing continuation boundaries
        let cross_boundary_query: Vec<LocalBlockHash> = (45..=105).map(LocalBlockHash).collect();
        let scores = index.find_matches(cross_boundary_query).await.unwrap();
        // Query starts at block 45, but stored sequence starts at 1, so this won't match
        // because the sequence hash at position 0 of our query (block 45) won't match
        // the stored sequence hash at position 0 (block 1)
        assert!(
            scores.scores.is_empty() || !scores.scores.contains_key(&WorkerWithDpRank::new(0, 0))
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_branching_continuations(variant: &str) {
        let index = make_indexer(variant);

        // Common prefix: blocks 1-30
        let common_prefix: Vec<u64> = (1..=30).collect();
        index.apply_event(make_store_event(0, &common_prefix)).await;

        // Branch A: blocks 31-60 on worker 0
        let branch_a: Vec<u64> = (31..=60).collect();
        index
            .apply_event(make_store_event_with_parent(0, &common_prefix, &branch_a))
            .await;

        // Branch B: blocks 131-160 (different content) on worker 1
        // First store the common prefix for worker 1
        index.apply_event(make_store_event(1, &common_prefix)).await;
        let branch_b: Vec<u64> = (131..=160).collect();
        index
            .apply_event(make_store_event_with_parent(1, &common_prefix, &branch_b))
            .await;

        flush_and_settle(index.as_ref()).await;

        // Query common prefix - both workers should match
        let prefix_query: Vec<LocalBlockHash> = (1..=30).map(LocalBlockHash).collect();
        let scores = index.find_matches(prefix_query).await.unwrap();
        assert_eq!(scores.scores.len(), 2);
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            30
        );
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(1, 0)).unwrap(),
            30
        );

        // Query branch A path - only worker 0 should match fully
        let branch_a_query: Vec<LocalBlockHash> = (1..=60).map(LocalBlockHash).collect();
        let scores = index.find_matches(branch_a_query).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            60
        );
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(1, 0)).unwrap(),
            30
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_partial_removal(variant: &str) {
        let index = make_indexer(variant);

        // Store a long sequence
        let sequence: Vec<u64> = (1..=100).collect();
        index.apply_event(make_store_event(0, &sequence)).await;

        flush_and_settle(index.as_ref()).await;

        // Verify full match
        let full_query: Vec<LocalBlockHash> = sequence.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(full_query.clone()).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            100
        );

        // Remove blocks 80-100 (the tail)
        let tail_hashes: Vec<LocalBlockHash> = (1..=100).map(LocalBlockHash).collect();
        let seq_hashes = compute_seq_hash_for_block(&tail_hashes);
        let remove_hashes: Vec<ExternalSequenceBlockHash> = seq_hashes[79..100]
            .iter()
            .map(|&h| ExternalSequenceBlockHash(h))
            .collect();

        let remove_event = remove_event(0, 0, 0, remove_hashes);
        index.apply_event(remove_event).await;

        flush_and_settle(index.as_ref()).await;

        // Query should now only match first 79 blocks
        let scores = index.find_matches(full_query).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            79
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_interleaved_workers(variant: &str) {
        let index = make_indexer(variant);

        // Multiple workers storing overlapping long sequences concurrently
        // Worker 0: blocks 1-100
        // Worker 1: blocks 1-75
        // Worker 2: blocks 1-50
        // Worker 3: blocks 1-25

        let seq_100: Vec<u64> = (1..=100).collect();
        let seq_75: Vec<u64> = (1..=75).collect();
        let seq_50: Vec<u64> = (1..=50).collect();
        let seq_25: Vec<u64> = (1..=25).collect();

        index.apply_event(make_store_event(0, &seq_100)).await;
        index.apply_event(make_store_event(1, &seq_75)).await;
        index.apply_event(make_store_event(2, &seq_50)).await;
        index.apply_event(make_store_event(3, &seq_25)).await;

        flush_and_settle(index.as_ref()).await;

        // Query for 60 blocks - workers 0,1 match 60, worker 2 matches 50, worker 3 matches 25
        let query_60: Vec<LocalBlockHash> = (1..=60).map(LocalBlockHash).collect();
        let scores = index.find_matches(query_60).await.unwrap();
        assert_eq!(scores.scores.len(), 4);
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            60
        );
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(1, 0)).unwrap(),
            60
        );
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(2, 0)).unwrap(),
            50
        );
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(3, 0)).unwrap(),
            25
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_exact_jump_size_boundaries(variant: &str) {
        let index = make_indexer(variant);

        // Test sequences that align exactly with jump_size boundaries (32 for PositionalIndexer)
        // This tests edge cases in the jump search algorithm

        // Store sequence of exactly 32 blocks
        let seq_32: Vec<u64> = (1..=32).collect();
        index.apply_event(make_store_event(0, &seq_32)).await;

        // Store sequence of exactly 64 blocks (2x jump_size)
        let seq_64: Vec<u64> = (1001..=1064).collect();
        index.apply_event(make_store_event(1, &seq_64)).await;

        // Store sequence of exactly 96 blocks (3x jump_size)
        let seq_96: Vec<u64> = (2001..=2096).collect();
        index.apply_event(make_store_event(2, &seq_96)).await;

        flush_and_settle(index.as_ref()).await;

        // Verify all sequences match correctly
        let query_32: Vec<LocalBlockHash> = seq_32.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(query_32).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            32
        );

        let query_64: Vec<LocalBlockHash> = seq_64.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(query_64).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(1, 0)).unwrap(),
            64
        );

        let query_96: Vec<LocalBlockHash> = seq_96.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(query_96).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(2, 0)).unwrap(),
            96
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_off_by_one_jump_boundaries(variant: &str) {
        let index = make_indexer(variant);

        // Test sequences at jump_size +/- 1 boundaries to catch off-by-one errors
        let seq_31: Vec<u64> = (1..=31).collect();
        let seq_33: Vec<u64> = (101..=133).collect();
        let seq_63: Vec<u64> = (201..=263).collect();
        let seq_65: Vec<u64> = (301..=365).collect();

        index.apply_event(make_store_event(0, &seq_31)).await;
        index.apply_event(make_store_event(1, &seq_33)).await;
        index.apply_event(make_store_event(2, &seq_63)).await;
        index.apply_event(make_store_event(3, &seq_65)).await;

        flush_and_settle(index.as_ref()).await;

        // Verify all sequences match correctly
        let query_31: Vec<LocalBlockHash> = seq_31.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(query_31).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            31
        );

        let query_33: Vec<LocalBlockHash> = seq_33.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(query_33).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(1, 0)).unwrap(),
            33
        );

        let query_63: Vec<LocalBlockHash> = seq_63.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(query_63).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(2, 0)).unwrap(),
            63
        );

        let query_65: Vec<LocalBlockHash> = seq_65.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(query_65).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(3, 0)).unwrap(),
            65
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_divergence_at_jump_boundaries(variant: &str) {
        let index = make_indexer(variant);

        // Store a long sequence
        let sequence: Vec<u64> = (1..=128).collect();
        index.apply_event(make_store_event(0, &sequence)).await;

        flush_and_settle(index.as_ref()).await;

        // Test divergence exactly at jump boundaries (position 31, 32, 33, 63, 64, 65)
        for diverge_pos in [31usize, 32, 33, 63, 64, 65, 95, 96, 97] {
            let mut query: Vec<LocalBlockHash> = (1..=128).map(LocalBlockHash).collect();
            query[diverge_pos] = LocalBlockHash(99999);

            let scores = index.find_matches(query).await.unwrap();
            assert_eq!(
                *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
                diverge_pos as u32,
                "Divergence at position {} should match {} blocks",
                diverge_pos,
                diverge_pos
            );
        }
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_deep_continuation_chain(variant: &str) {
        let index = make_indexer(variant);

        // Build a very long sequence through many small continuations
        // This tests the parent_hash chain handling
        let chunk_size = 10;
        let num_chunks = 20; // Total 200 blocks

        let mut full_prefix: Vec<u64> = Vec::new();

        for chunk_idx in 0..num_chunks {
            let chunk_start = chunk_idx * chunk_size + 1;
            let chunk: Vec<u64> = (chunk_start..chunk_start + chunk_size)
                .map(|x| x as u64)
                .collect();

            if chunk_idx == 0 {
                index.apply_event(make_store_event(0, &chunk)).await;
            } else {
                index
                    .apply_event(make_store_event_with_parent(0, &full_prefix, &chunk))
                    .await;
            }

            full_prefix.extend(&chunk);
        }

        flush_and_settle(index.as_ref()).await;

        // Query full sequence
        let full_query: Vec<LocalBlockHash> = (1..=200).map(LocalBlockHash).collect();
        let scores = index.find_matches(full_query).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            200
        );

        // Query partial prefix crossing multiple chunk boundaries
        let partial_query: Vec<LocalBlockHash> = (1..=75).map(LocalBlockHash).collect();
        let scores = index.find_matches(partial_query).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            75
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_clear_and_rebuild(variant: &str) {
        let index = make_indexer(variant);

        // Store a long sequence
        let sequence: Vec<u64> = (1..=100).collect();
        index.apply_event(make_store_event(0, &sequence)).await;

        flush_and_settle(index.as_ref()).await;

        // Verify it's stored
        let query: Vec<LocalBlockHash> = sequence.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(query.clone()).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            100
        );

        // Clear the worker
        index.apply_event(make_clear_event(0)).await;

        flush_and_settle(index.as_ref()).await;

        // Verify it's cleared
        let scores = index.find_matches(query.clone()).await.unwrap();
        assert!(scores.scores.is_empty());

        // Rebuild with a different sequence
        let new_sequence: Vec<u64> = (1001..=1100).collect();
        index.apply_event(make_store_event(0, &new_sequence)).await;

        flush_and_settle(index.as_ref()).await;

        // Verify new sequence works
        let new_query: Vec<LocalBlockHash> =
            new_sequence.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(new_query).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            100
        );

        // Verify old sequence no longer matches
        let scores = index.find_matches(query).await.unwrap();
        assert!(scores.scores.is_empty());
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_multiple_workers_diverging(variant: &str) {
        let index = make_indexer(variant);

        // Multiple workers with long sequences that share a prefix then diverge
        // This tests precise drain point tracking across workers

        // All workers share prefix 1-40
        let shared_prefix: Vec<u64> = (1..=40).collect();

        // Worker 0: prefix + 41-100 (stores full sequence 1-100)
        let worker_0_full: Vec<u64> = (1..=100).collect();

        // Worker 1: prefix + 141-180 (diverges at block 41)
        let worker_1_suffix: Vec<u64> = (141..=180).collect();

        // Worker 2: prefix + 241-300 (diverges at block 41)
        let worker_2_suffix: Vec<u64> = (241..=300).collect();

        // Store for all workers
        index.apply_event(make_store_event(0, &worker_0_full)).await;

        index.apply_event(make_store_event(1, &shared_prefix)).await;
        index
            .apply_event(make_store_event_with_parent(
                1,
                &shared_prefix,
                &worker_1_suffix,
            ))
            .await;

        index.apply_event(make_store_event(2, &shared_prefix)).await;
        index
            .apply_event(make_store_event_with_parent(
                2,
                &shared_prefix,
                &worker_2_suffix,
            ))
            .await;

        flush_and_settle(index.as_ref()).await;

        // Query 1-100 - worker 0 matches 100, workers 1&2 match 40
        let query: Vec<LocalBlockHash> = worker_0_full.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(query).await.unwrap();

        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            100
        );
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(1, 0)).unwrap(),
            40
        );
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(2, 0)).unwrap(),
            40
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_long_sequence_staggered_lengths(variant: &str) {
        let index = make_indexer(variant);

        // Workers with sequences of staggered lengths to test drain tracking
        // Worker 0: 10 blocks
        // Worker 1: 20 blocks
        // Worker 2: 35 blocks (just past first jump)
        // Worker 3: 64 blocks (exactly 2 jumps)
        // Worker 4: 100 blocks

        for (worker_id, len) in [(0, 10), (1, 20), (2, 35), (3, 64), (4, 100)] {
            let sequence: Vec<u64> = (1..=len).collect();
            index
                .apply_event(make_store_event(worker_id, &sequence))
                .await;
        }

        flush_and_settle(index.as_ref()).await;

        // Query for 100 blocks - each worker should match their stored length
        let query: Vec<LocalBlockHash> = (1..=100).map(LocalBlockHash).collect();
        let scores = index.find_matches(query).await.unwrap();

        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            10
        );
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(1, 0)).unwrap(),
            20
        );
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(2, 0)).unwrap(),
            35
        );
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(3, 0)).unwrap(),
            64
        );
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(4, 0)).unwrap(),
            100
        );
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_very_long_sequence(variant: &str) {
        let index = make_indexer(variant);

        // Test with a very long sequence (1000 blocks)
        let seq_len = 1000u64;
        let sequence: Vec<u64> = (1..=seq_len).collect();
        index.apply_event(make_store_event(0, &sequence)).await;

        flush_and_settle(index.as_ref()).await;

        // Full match
        let full_query: Vec<LocalBlockHash> = sequence.iter().map(|&i| LocalBlockHash(i)).collect();
        let scores = index.find_matches(full_query).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            seq_len as u32
        );

        // Partial match (first 500)
        let partial_query: Vec<LocalBlockHash> = (1..=500).map(LocalBlockHash).collect();
        let scores = index.find_matches(partial_query).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            500
        );

        // Divergence in the middle
        let mut mid_diverge: Vec<LocalBlockHash> = (1..=1000).map(LocalBlockHash).collect();
        mid_diverge[499] = LocalBlockHash(99999);
        let scores = index.find_matches(mid_diverge).await.unwrap();
        assert_eq!(
            *scores.scores.get(&WorkerWithDpRank::new(0, 0)).unwrap(),
            499
        );
    }
}

// ============================================================================
// Tests specific to tree-based implementations (KvIndexer, KvIndexerSharded)
// These use features not available in PositionalIndexer
// ============================================================================

#[template]
#[rstest]
fn tree_indexer_template(#[values("single", "sharded")] variant: &str) {}

fn make_tree_indexer_with_frequency(
    variant: &str,
    expiration: Duration,
) -> Box<dyn KvIndexerInterface> {
    let token = CancellationToken::new();
    let metrics = Arc::new(KvIndexerMetrics::new_unregistered());
    let kv_block_size = 32;

    match variant {
        "single" => Box::new(KvIndexer::new_with_frequency(
            token,
            Some(expiration),
            kv_block_size,
            metrics,
            None,
        )),
        "sharded" => Box::new(KvIndexerSharded::new_with_frequency(
            token,
            4,
            Some(expiration),
            kv_block_size,
            metrics,
            None,
        )),
        _ => panic!("Unknown variant: {}", variant),
    }
}

mod tree_specific_tests {
    use super::*;
    use rstest_reuse::apply;

    #[tokio::test]
    #[apply(tree_indexer_template)]
    async fn test_frequency(variant: &str) {
        const ONE_MILLIS: Duration = Duration::from_millis(1);

        let expiration = Duration::from_millis(50);
        let kv_indexer = make_tree_indexer_with_frequency(variant, expiration);

        // The blocks
        let block_hashes = vec![
            LocalBlockHash(1),
            LocalBlockHash(2),
            LocalBlockHash(3),
            LocalBlockHash(4),
        ];

        let overlap = kv_indexer.find_matches(block_hashes.clone()).await.unwrap();
        assert_eq!(
            overlap.frequencies.len(),
            0,
            "Should be no cached blocks yet"
        );

        // Blocks go in cache
        let event = make_store_event(0, &[1, 2, 3, 4]);
        kv_indexer.apply_event(event).await;

        // First access - poll briefly since store event is applied async
        let mut overlap = OverlapScores::default();
        let timeout = Duration::from_millis(10);
        let start = Instant::now();
        while overlap.scores.is_empty() && Instant::now().duration_since(start) < timeout {
            time::sleep(ONE_MILLIS).await;
            overlap = kv_indexer.find_matches(block_hashes.clone()).await.unwrap();
        }
        assert_eq!(
            overlap.scores.len(),
            1,
            "One worker has these blocks cached"
        );
        assert_eq!(
            overlap.frequencies.len(),
            0,
            "Blocks have not previously been accessed"
        );

        // Second access
        let overlap = kv_indexer.find_matches(block_hashes.clone()).await.unwrap();
        assert_eq!(overlap.scores.len(), 1, "Still one worker matches");
        assert_eq!(
            overlap.frequencies,
            vec![1, 1, 1, 1],
            "We should see the first access now"
        );

        // Let those two accesses expire
        time::sleep(expiration + Duration::from_millis(10)).await;

        // New first access
        let overlap = kv_indexer.find_matches(block_hashes.clone()).await.unwrap();
        assert_eq!(
            overlap.frequencies.len(),
            0,
            "Blocks were accessed too long ago"
        );

        // New second access
        let _ = kv_indexer.find_matches(block_hashes.clone()).await.unwrap();

        // Access only the first three blocks
        let overlap = kv_indexer
            .find_matches(block_hashes[0..3].to_vec())
            .await
            .unwrap();
        // We see the previous two new accesses
        assert_eq!(overlap.frequencies, vec![2, 2, 2]);

        // The third access did not touch the last block
        let overlap = kv_indexer.find_matches(block_hashes.clone()).await.unwrap();
        assert_eq!(overlap.frequencies, vec![3, 3, 3, 2]);
    }
}

// ============================================================================
// KvIndexerMetrics tests
// ============================================================================

mod metrics_tests {
    #[cfg(feature = "metrics")]
    use super::*;

    #[cfg(feature = "metrics")]
    #[test]
    fn test_increment_event_applied() {
        let metrics = KvIndexerMetrics::new_unregistered();

        metrics.increment_event_applied(METRIC_EVENT_STORED, Ok(()));
        assert_eq!(
            metrics
                .kv_cache_events_applied
                .get_metric_with_label_values(&[METRIC_EVENT_STORED, METRIC_STATUS_OK])
                .unwrap()
                .get(),
            1
        );

        metrics.increment_event_applied(
            METRIC_EVENT_STORED,
            Err(KvCacheEventError::ParentBlockNotFound),
        );
        assert_eq!(
            metrics
                .kv_cache_events_applied
                .get_metric_with_label_values(&[
                    METRIC_EVENT_STORED,
                    METRIC_STATUS_PARENT_NOT_FOUND
                ])
                .unwrap()
                .get(),
            1
        );

        metrics
            .increment_event_applied(METRIC_EVENT_REMOVED, Err(KvCacheEventError::BlockNotFound));
        assert_eq!(
            metrics
                .kv_cache_events_applied
                .get_metric_with_label_values(&[
                    METRIC_EVENT_REMOVED,
                    METRIC_STATUS_BLOCK_NOT_FOUND
                ])
                .unwrap()
                .get(),
            1
        );
    }
}

// ============================================================================
// LocalKvIndexer tests
// ============================================================================

fn make_local_indexer_with_events(ids: &[u64]) -> LocalKvIndexer {
    let indexer = LocalKvIndexer::new(
        CancellationToken::new(),
        4,
        Arc::new(KvIndexerMetrics::new_unregistered()),
        32,
    );
    {
        let mut buffer = indexer.event_buffer.lock().unwrap();
        for &id in ids {
            buffer.push_back(RouterEvent::new(
                0,
                KvCacheEvent {
                    event_id: id,
                    data: KvCacheEventData::Cleared,
                    dp_rank: 0,
                },
            ));
        }
    }
    indexer
}

mod local_indexer_tests {
    use super::*;
    use rstest_reuse::apply;

    #[tokio::test]
    async fn test_local_indexer_slice_within_range() {
        let indexer = make_local_indexer_with_events(&[1, 2, 3, 4, 5]);

        // Helper to extract events from response
        let extract_events = |resp: WorkerKvQueryResponse| -> Vec<RouterEvent> {
            match resp {
                WorkerKvQueryResponse::Events(e) => e,
                WorkerKvQueryResponse::TreeDump { events: e, .. } => e,
                _ => panic!("Unexpected response type"),
            }
        };

        let get_ids = |events: Vec<RouterEvent>| -> Vec<u64> {
            events.iter().map(|e| e.event.event_id).collect()
        };

        // Test get_events_in_id_range (buffer queries)
        // Range is [start, end] inclusive
        let result = indexer.get_events_in_id_range(Some(2), Some(4)).await;
        let ids = get_ids(extract_events(result));
        assert_eq!(ids, vec![2, 3, 4]); // inclusive range [2, 4]

        let result = indexer.get_events_in_id_range(Some(2), Some(6)).await;
        let ids = get_ids(extract_events(result));
        assert_eq!(ids, vec![2, 3, 4, 5]); // clamp end to buffer max

        // start_id=0 is before buffer (first is 1), so should trigger tree dump
        let result = indexer.get_events_in_id_range(Some(0), Some(4)).await;
        assert!(matches!(result, WorkerKvQueryResponse::TreeDump { .. }));

        let result = indexer.get_events_in_id_range(Some(3), Some(3)).await;
        let ids = get_ids(extract_events(result));
        assert_eq!(ids, vec![3]); // single element when start == end

        // Invalid range: end < start
        let result = indexer.get_events_in_id_range(Some(5), Some(2)).await;
        assert!(matches!(result, WorkerKvQueryResponse::InvalidRange { .. }));
    }

    #[tokio::test]
    async fn test_local_indexer_get_events_in_id_range_all_cases() {
        // Create indexer with small buffer (5 events max)
        let indexer = LocalKvIndexer::new(
            CancellationToken::new(),
            4,
            Arc::new(KvIndexerMetrics::new_unregistered()),
            5,
        );

        // Helper to create a test event
        let make_event = |id: u64| {
            RouterEvent::new(
                0,
                KvCacheEvent {
                    event_id: id,
                    data: KvCacheEventData::Stored(KvCacheStoreData {
                        parent_hash: None,
                        blocks: vec![KvCacheStoredBlockData {
                            block_hash: ExternalSequenceBlockHash(id * 100),
                            tokens_hash: LocalBlockHash(id * 200),
                            mm_extra_info: None,
                        }],
                    }),
                    dp_rank: 0,
                },
            )
        };

        // Add 10 events (IDs 5-14), buffer keeps last 5: events 10-14
        for id in 5..15 {
            indexer
                .apply_event_with_buffer(make_event(id))
                .await
                .unwrap();
        }

        // Wait for events to be processed
        indexer.flush().await;

        let extract_events = |resp: WorkerKvQueryResponse| -> Vec<RouterEvent> {
            match resp {
                WorkerKvQueryResponse::Events(e) => e,
                WorkerKvQueryResponse::TreeDump { events: e, .. } => e,
                _ => panic!("Unexpected response type: {:?}", resp),
            }
        };

        let get_ids = |events: Vec<RouterEvent>| -> Vec<u64> {
            events.iter().map(|e| e.event.event_id).collect()
        };

        // Verify buffer state
        let buffer_events = indexer.get_all_events_in_buffer();
        assert_eq!(get_ids(buffer_events), vec![10, 11, 12, 13, 14]);

        // Buffer path tests
        let result = indexer.get_events_in_id_range(Some(11), None).await;
        assert_eq!(get_ids(extract_events(result)), vec![11, 12, 13, 14]);

        let result = indexer.get_events_in_id_range(Some(10), Some(14)).await;
        assert_eq!(get_ids(extract_events(result)), vec![10, 11, 12, 13, 14]);

        // Tree dump path tests
        let result = indexer.get_events_in_id_range(None, None).await;
        assert!(matches!(&result, WorkerKvQueryResponse::TreeDump { .. }));
        assert_eq!(extract_events(result).len(), 10);

        let result = indexer.get_events_in_id_range(Some(7), None).await;
        assert!(matches!(result, WorkerKvQueryResponse::TreeDump { .. }));

        // Edge cases
        let result = indexer.get_events_in_id_range(Some(15), Some(10)).await;
        assert!(matches!(result, WorkerKvQueryResponse::InvalidRange { .. }));

        let result = indexer.get_events_in_id_range(Some(100), Some(200)).await;
        assert!(matches!(result, WorkerKvQueryResponse::TooNew { .. }));
    }

    #[tokio::test]
    async fn test_tree_dump_includes_last_event_id() {
        // Create indexer with small buffer (5 events max)
        let indexer = LocalKvIndexer::new(
            CancellationToken::new(),
            4,
            Arc::new(KvIndexerMetrics::new_unregistered()),
            5,
        );

        let make_event = |id: u64| {
            RouterEvent::new(
                0,
                KvCacheEvent {
                    event_id: id,
                    data: KvCacheEventData::Stored(KvCacheStoreData {
                        parent_hash: None,
                        blocks: vec![KvCacheStoredBlockData {
                            block_hash: ExternalSequenceBlockHash(id * 100),
                            tokens_hash: LocalBlockHash(id * 200),
                            mm_extra_info: None,
                        }],
                    }),
                    dp_rank: 0,
                },
            )
        };

        // Add 10 events (IDs 5-14), buffer keeps last 5: events 10-14
        for id in 5..15 {
            indexer
                .apply_event_with_buffer(make_event(id))
                .await
                .unwrap();
        }
        indexer.flush().await;

        // Request with start_id=None -> tree dump should include last_event_id=14
        let result = indexer.get_events_in_id_range(None, None).await;
        match result {
            WorkerKvQueryResponse::TreeDump {
                last_event_id,
                events,
            } => {
                assert_eq!(
                    last_event_id, 14,
                    "last_event_id should be the buffer's newest event ID"
                );
                assert!(!events.is_empty(), "tree dump should contain events");
            }
            other => panic!("Expected TreeDump, got: {other:?}"),
        }

        // Request with start_id older than buffer -> tree dump should include last_event_id=14
        let result = indexer.get_events_in_id_range(Some(7), None).await;
        match result {
            WorkerKvQueryResponse::TreeDump {
                last_event_id,
                events,
            } => {
                assert_eq!(
                    last_event_id, 14,
                    "last_event_id should be the buffer's newest event ID"
                );
                assert!(!events.is_empty(), "tree dump should contain events");
            }
            other => panic!("Expected TreeDump, got: {other:?}"),
        }

        // Empty buffer case: create a fresh indexer with no events
        let empty_indexer = LocalKvIndexer::new(
            CancellationToken::new(),
            4,
            Arc::new(KvIndexerMetrics::new_unregistered()),
            5,
        );
        let result = empty_indexer.get_events_in_id_range(None, None).await;
        match result {
            WorkerKvQueryResponse::TreeDump {
                last_event_id,
                events,
            } => {
                assert_eq!(
                    last_event_id, 0,
                    "empty buffer should return last_event_id=0"
                );
                assert!(events.is_empty(), "empty indexer should have no events");
            }
            other => panic!("Expected TreeDump, got: {other:?}"),
        }
    }

    #[tokio::test]
    async fn test_local_indexer_buffer_and_serialization() {
        let worker_id = 42u64;
        let token = CancellationToken::new();
        let metrics = Arc::new(KvIndexerMetrics::new_unregistered());
        let local_indexer = Arc::new(LocalKvIndexer::new(token, 4, metrics, 100));

        let test_event = RouterEvent::new(
            worker_id,
            KvCacheEvent {
                event_id: 1,
                data: KvCacheEventData::Stored(KvCacheStoreData {
                    parent_hash: None,
                    blocks: vec![KvCacheStoredBlockData {
                        block_hash: ExternalSequenceBlockHash(100),
                        tokens_hash: LocalBlockHash(200),
                        mm_extra_info: None,
                    }],
                }),
                dp_rank: 0,
            },
        );

        local_indexer
            .apply_event_with_buffer(test_event)
            .await
            .unwrap();

        local_indexer.flush().await;

        let buffered_events = local_indexer.get_all_events_in_buffer();
        assert_eq!(buffered_events.len(), 1);
        assert_eq!(buffered_events[0].worker_id, worker_id);

        // Test serialization round-trip
        let response = WorkerKvQueryResponse::Events(buffered_events);
        let serialized = serde_json::to_vec(&response).unwrap();
        let deserialized: WorkerKvQueryResponse = serde_json::from_slice(&serialized).unwrap();

        let events = match deserialized {
            WorkerKvQueryResponse::Events(e) => e,
            _ => panic!("Expected Events variant"),
        };
        assert_eq!(events.len(), 1);
        assert_eq!(events[0].worker_id, worker_id);
    }

    #[tokio::test]
    async fn test_local_indexer_does_not_buffer_failed_send() {
        let local_indexer = LocalKvIndexer::new(
            CancellationToken::new(),
            4,
            Arc::new(KvIndexerMetrics::new_unregistered()),
            5,
        );

        let test_event = RouterEvent::new(
            7,
            KvCacheEvent {
                event_id: 1,
                data: KvCacheEventData::Stored(KvCacheStoreData {
                    parent_hash: None,
                    blocks: vec![KvCacheStoredBlockData {
                        block_hash: ExternalSequenceBlockHash(100),
                        tokens_hash: LocalBlockHash(200),
                        mm_extra_info: None,
                    }],
                }),
                dp_rank: 0,
            },
        );

        let event_tx = local_indexer.event_sender();
        local_indexer.shutdown();
        event_tx.closed().await;

        let result = local_indexer.apply_event_with_buffer(test_event).await;
        assert!(matches!(result, Err(KvRouterError::IndexerOffline)));
        assert_eq!(local_indexer.buffer_len(), 0);

        match local_indexer.get_events_in_id_range(None, None).await {
            WorkerKvQueryResponse::TreeDump {
                events,
                last_event_id,
            } => {
                assert!(events.is_empty());
                assert_eq!(last_event_id, 0);
            }
            other => panic!("Expected TreeDump, got: {other:?}"),
        }
    }

    #[tokio::test]
    #[apply(indexer_template)]
    async fn test_apply_events_idempotent(variant: &str) {
        let index = make_indexer(variant);

        // Setup: build initial tree
        index.apply_event(make_store_event(0, &[1, 2, 3])).await;
        index.apply_event(make_store_event(1, &[4, 5, 6])).await;
        index
            .apply_event(make_store_event_with_parent(0, &[1, 2, 3], &[7, 8]))
            .await;
        flush_and_settle(index.as_ref()).await;
        let s0 = snapshot_tree(index.as_ref()).await;

        // Mutation events: each add paired with its remove
        let adds = [
            make_store_event(2, &[1, 2, 9]),
            make_store_event_with_parent(1, &[4, 5, 6], &[10, 11, 12]),
        ];
        let removes = [
            make_remove_event(2, &[1, 2, 9]),
            make_remove_event_with_parent(1, &[4, 5, 6], &[10, 11, 12]),
        ];

        // Phase 1: interleaved add/remove
        index.apply_event(adds[0].clone()).await;
        index.apply_event(removes[0].clone()).await;
        index.apply_event(adds[1].clone()).await;
        index.apply_event(removes[1].clone()).await;
        flush_and_settle(index.as_ref()).await;
        let s1 = snapshot_tree(index.as_ref()).await;
        assert_eq!(
            s0, s1,
            "Phase 1: interleaved add/remove should restore tree"
        );

        // Phase 2: same interleaved again (idempotence of the full cycle)
        index.apply_event(adds[0].clone()).await;
        index.apply_event(removes[0].clone()).await;
        index.apply_event(adds[1].clone()).await;
        index.apply_event(removes[1].clone()).await;
        flush_and_settle(index.as_ref()).await;
        let s2 = snapshot_tree(index.as_ref()).await;
        assert_eq!(s1, s2, "Phase 2: repeated cycle should be idempotent");

        // Phase 3: non-interleaved (all adds then all removes)
        index.apply_event(adds[0].clone()).await;
        index.apply_event(adds[1].clone()).await;
        index.apply_event(removes[0].clone()).await;
        index.apply_event(removes[1].clone()).await;
        flush_and_settle(index.as_ref()).await;
        let s3 = snapshot_tree(index.as_ref()).await;
        assert_eq!(
            s2, s3,
            "Phase 3: non-interleaved ordering should restore tree"
        );
    }
}