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L4 workflows reconstruct order-level book state from snapshots, ordered diffs, and gap signals. They require a known venue family, symbol, baseline source, ordered updates, gap policy, and recovery path. A client that cannot satisfy those requirements will produce an unreliable local book. This L4 workflow applies to Hyperliquid core, Spot, HIP-3, and HIP-4. Only Hyperliquid core L4 supports WebSocket replay. Spot, HIP-3, and HIP-4 L4 channels are real-time only, with historical reconstruction handled through their REST history and checkpoint routes. Lighter exposes L3 individual-order depth instead.
SnapshotStart from a checkpointPull an L4 snapshot for one family and symbol, or use a WebSocket replay baseline for Hyperliquid core.
DiffsApply updates in orderProcess server-ordered diffs without dropping or reordering messages. Retain each event’s block/order metadata. Honor the optional insert_before key on new-order diffs: it names the resting order ID the new order queue-jumps ahead of; absent means append at the tail.
Live bookHold current stateOn a gap event, mark the book unsafe and rebuild from a fresh checkpoint.

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L4 Workflow

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Implementation Pattern

1

Confirm route availability

L4 routes are a route-availability question, separate from connection, replay, and throughput limits. Verify the selected symbol’s published coverage before requesting history, then size the client against WebSocket limits and the account’s published plan terms.
2

Start with one symbol

Confirm the local book can process a small stream before widening to more markets.
3

Separate UI from book state

Drop or throttle noncritical UI updates before dropping book events.
4

Stop on unsafe gaps

If the book misses ordered events, mark it unsafe and rebuild from a known baseline.

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L4 State Checklist

Capture this checklist before claiming a client maintains an L4 book.

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REST And WebSocket Together

Use REST when you need point snapshots or bounded historical L4 records. Use WebSocket for live updates on every L4 family. Use WebSocket replay only for Hyperliquid core l4_diffs and l4_orders. A production L4 client often uses REST for baseline and recovery, WebSocket for live state, and data-quality routes for trust decisions; core clients can also use checkpoint-anchored WebSocket replay. Do not collapse L4 into a generic “orderbook” label in storage. Store whether the data is L2, L3, L4, current, historical, replayed, or reconstructed. That distinction matters for backtests, visualizations, alerting, and customer-facing products.

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Next Step

Open WebSocket channels, WebSocket replay, SDK reconstruction, and the relevant REST family before implementing a local book.
Last modified on August 28, 2026