fix: drop orderbook deltas before snapshot instead of creating ghost entries

CHANGELOG.md

@@ -5,6 +5,26 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- `OrderbookAggregator` now drops delta messages that arrive before a snapshot
+  instead of creating ghost orderbook entries. Previously, early deltas would
+  insert empty uninitialized books into the state map, causing `full_book()` and
+  `tracked_markets()` to return stale or invalid data.
+
+### Changed
+
+- **Breaking:** Removed `initialized` field from `OrderbookSummary`. The
+  aggregator now guarantees that summaries are only produced for fully
+  initialized orderbooks, making the field redundant. Remove any
+  `summary.initialized` checks from your code.
+- `Channel::requires_market_ticker()` now returns `true` only for
+  `OrderbookDelta`. Other market data channels (`Ticker`, `Trade`,
+  `MarketLifecycle`, `Multivariate`) support subscribing with an empty ticker
+  list to receive updates for all markets.
+
 ## [0.2.0] - 2026-01-18
 
 ### Added

examples/orderbook_aggregator.rs

@@ -216,11 +216,8 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
             last_summary_time = std::time::Instant::now();
             for ticker in &market_tickers {
                 match aggregator.full_book(ticker) {
-                    Some(ladder) if aggregator.is_initialized(ticker) => {
-                        print_ladder(&ladder);
-                    }
-                    Some(_) => println!("{}: waiting for snapshot...", ticker),
-                    None => println!("{}: not tracked", ticker),
+                    Some(ladder) => print_ladder(&ladder),
+                    None => println!("{}: waiting for snapshot...", ticker),
                 }
             }
         }

examples/stream_firehose.rs

@@ -15,8 +15,8 @@
 //! cargo run --example stream_firehose
 //! ```
 
-use std::time::Duration;
 use kalshi_trade_rs::{Channel, KalshiConfig, KalshiStreamClient, StreamMessage};
+use std::time::Duration;
 use tokio::time::timeout;
 
 #[tokio::main]
@@ -90,7 +90,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
                         "[TRADE]  {} | {} contracts @ {}¢ | taker: {:?}",
                         trade.market_ticker, trade.count, trade.yes_price, trade.taker_side
                     );
-                },
+                }
                 StreamMessage::MarketLifecycle(lifecycle) => {
                     println!(
                         "[LIFECYCLE] {} | event={:?} | open={:?} | close={:?} | result={:?}",
@@ -115,7 +115,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
                             leg.market_ticker, leg.side
                         );
                     }
-                },
+                }
                 StreamMessage::MarketPosition(pos) => {
                     println!(
                         "[POSITION] {} | position={:?} | cost={:?} | pnl={:?}",

src/orderbook/aggregator.rs

@@ -27,8 +27,6 @@ pub struct OrderbookSummary {
     pub total_yes_liquidity: i64,
     /// Total NO side liquidity.
     pub total_no_liquidity: i64,
-    /// Whether the orderbook has been initialized with a snapshot.
-    pub initialized: bool,
 }
 
 /// What changed in an orderbook update.
@@ -256,9 +254,14 @@ impl OrderbookAggregator {
     fn handle_delta(&self, delta: &crate::ws::OrderbookDeltaData, seq: Option<i64>) {
         let ticker = delta.market_ticker.clone();
 
-        let (new_qty, should_emit) = {
+        let new_qty = {
             let mut state = self.state.write().expect("state lock poisoned");
-            let orderbook = state.entry(ticker.clone()).or_default();
+            let Some(orderbook) = state.get_mut(&ticker) else {
+                return;
+            };
+            if !orderbook.is_initialized() {
+                return;
+            }
 
             // Check sequence gap for this specific market
             if let (Some(last), Some(new)) = (orderbook.last_seq(), seq)
@@ -273,13 +276,10 @@ impl OrderbookAggregator {
             }
 
             orderbook.update_seq(seq);
-            let new_qty = orderbook.apply_delta(delta);
-
-            (new_qty, orderbook.is_initialized())
+            orderbook.apply_delta(delta)
         };
 
-        // Only emit updates if we've seen a snapshot
-        if should_emit && let Some(summary) = self.summary(&ticker) {
+        if let Some(summary) = self.summary(&ticker) {
             let _ = self.update_sender.send(OrderbookUpdate {
                 ticker,
                 summary,
@@ -328,7 +328,6 @@ impl OrderbookAggregator {
             midpoint: orderbook.midpoint(),
             total_yes_liquidity: orderbook.total_yes_liquidity(),
             total_no_liquidity: orderbook.total_no_liquidity(),
-            initialized: orderbook.is_initialized(),
         })
     }
 
@@ -553,7 +552,6 @@ mod tests {
         assert_eq!(summary.midpoint, Some(46.0));
         assert_eq!(summary.total_yes_liquidity, 300);
         assert_eq!(summary.total_no_liquidity, 150);
-        assert!(summary.initialized);
     }
 
     #[test]
@@ -588,6 +586,78 @@ mod tests {
         assert_eq!(agg.depth_at_price("UNKNOWN", Side::Yes, 45), 0); // Unknown market
     }
 
+    #[test]
+    fn test_full_book() {
+        let agg = OrderbookAggregator::new();
+
+        assert!(agg.full_book("UNKNOWN").is_none());
+
+        // Snapshot creates initial book
+        let snapshot = OrderbookSnapshotData {
+            market_ticker: "TEST".to_string(),
+            yes: Some(vec![[45, 100], [44, 200]]),
+            yes_dollars: None,
+            no: Some(vec![[55, 150]]),
+            no_dollars: None,
+        };
+        agg.handle_snapshot(&snapshot);
+
+        // Apply deltas: add a new level, remove an existing one
+        agg.handle_delta(
+            &OrderbookDeltaData {
+                market_ticker: "TEST".to_string(),
+                price: 46,
+                delta: 75,
+                side: Side::Yes,
+                price_dollars: None,
+                client_order_id: None,
+            },
+            Some(1),
+        );
+        agg.handle_delta(
+            &OrderbookDeltaData {
+                market_ticker: "TEST".to_string(),
+                price: 44,
+                delta: -200,
+                side: Side::Yes,
+                price_dollars: None,
+                client_order_id: None,
+            },
+            Some(2),
+        );
+
+        let ladder = agg.full_book("TEST").unwrap();
+        // Level 46 was added, level 44 was removed
+        assert_eq!(ladder.yes_levels.len(), 2);
+        assert_eq!(ladder.yes_levels[&46], 75);
+        assert_eq!(ladder.yes_levels[&45], 100);
+        assert!(!ladder.yes_levels.contains_key(&44));
+        // NO side unchanged
+        assert_eq!(ladder.no_levels[&55], 150);
+    }
+
+    #[test]
+    fn test_delta_before_snapshot_ignored() {
+        let agg = OrderbookAggregator::new();
+
+        // Deltas before snapshot: no entry exists, delta is dropped
+        agg.handle_delta(
+            &OrderbookDeltaData {
+                market_ticker: "TEST".to_string(),
+                price: 45,
+                delta: 100,
+                side: Side::Yes,
+                price_dollars: None,
+                client_order_id: None,
+            },
+            Some(1),
+        );
+
+        // No entry was created — full_book returns None
+        assert!(agg.full_book("TEST").is_none());
+        assert!(agg.tracked_markets().is_empty());
+    }
+
     #[test]
     fn test_clone_shares_state() {
         let agg1 = OrderbookAggregator::new();

src/orderbook/mod.rs

@@ -30,11 +30,9 @@
 //! // Query orderbook state
 //! loop {
 //!     if let Some(summary) = aggregator.summary("TICKER-1") {
-//!         if summary.initialized {
-//!             println!("Spread: {:?} cents", summary.spread);
-//!             println!("Best bid: {:?}", summary.best_bid);
-//!             println!("Best ask: {:?}", summary.best_ask);
-//!         }
+//!         println!("Spread: {:?} cents", summary.spread);
+//!         println!("Best bid: {:?}", summary.best_bid);
+//!         println!("Best ask: {:?}", summary.best_ask);
 //!     }
 //!     tokio::time::sleep(Duration::from_millis(100)).await;
 //! }

src/ws/channel.rs

@@ -36,9 +36,11 @@ impl Channel {
 
     /// Returns true if this channel requires at least one market ticker.
     ///
-    /// Channels like `Fill` and `Communications` are user-scoped and don't
-    /// require market tickers. Market data channels like `OrderbookDelta`,
-    /// `Ticker`, and `Trade` require at least one market ticker.
+    /// Only [`OrderbookDelta`](Self::OrderbookDelta) requires market tickers.
+    /// Other market data channels (`Ticker`, `Trade`, `MarketLifecycle`,
+    /// `Multivariate`) support subscribing with an empty ticker list to
+    /// receive updates for all markets. User-scoped channels (`Fill`,
+    /// `MarketPositions`, `Communications`) never require tickers.
     pub fn requires_market_ticker(&self) -> bool {
         matches!(self, Self::OrderbookDelta)
     }