new_bids is moved by into_order_args_iter() here, but later (under #[cfg(feature = "debug")]) it’s borrowed again in log_orders(&new_bids, ...), which will not compile. Consider iterating over new_bids.clone(), moving logging before consuming, or building the iterator from a clone/borrow.

removed_bid_indices/removed_ask_indices are derived from the user seat’s user_order_sectors, but the mapping is never cleared/updated. The subsequent remove_at calls will free/reuse those sectors, leaving the seat mapping pointing to invalid sectors and corrupting state. Ensure the seat’s order sector mappings are freed/updated atomically with the book removals.

The docs reference NewOrders::order_args / NewOrders::num_orders, but the type is Orders. This looks like a stale rename and makes the public API docs misleading; update these references to Orders::....

to_sector_indices doesn't remove anything; it only returns a copy of the current sector indices. The docstring currently says it "Removes all mapped" elements, which is incorrect and could cause callers to assume the mapping is cleared. Please update the comment (or adjust the function to actually clear the mapping, if that's the intended behavior).

The market account in this Mollusk setup has data_len = 0 (uninitialized) and there is no registered seat for user_address, but the on-chain handlers validate initialization and then attempt to locate the user’s seat. As written, the assert!(result.program_result.is_ok()) expectation is not compatible with the program’s validation logic. Either initialize a real market+seat in Mollusk (e.g., run RegisterMarket/seat creation flows) or assert the expected initialization error for now.

The handler currently returns Ok(()) after only partial cancellation logic and without posting replacement orders. Since entrypoint routes BatchReplace here, consider returning a deterministic error until the full atomic replace behavior (cancel+refund+post+mapping updates) is implemented.

num_new_bids, num_new_asks, and bid_infos are currently unused, and bid_infos is never consumed (so any intended validation/conversion doesn’t run). Please remove these until needed, or ensure the iterator is actually used as part of the replace logic.

The module doc comment references process_batch, but that function/module was removed. Update the docs to reference process_batch_replace (or the correct instruction handler) so rustdoc links remain valid.

Orders derives Unpack, so num_orders can be attacker-controlled when deserializing instruction data. into_order_args_iter currently trusts num_orders and will silently clamp via .take(n), which can mask invalid data and risks future out-of-bounds/panic if num_orders is later used for indexing/loop bounds. Consider validating num_orders <= MAX_ORDERS during unpack (custom Unpack impl) or provide a checked accessor that returns InvalidInstructionData when num_orders is out of range.

Doc comments reference NewOrders::..., but the type is named Orders. Update these intra-doc links to point at Orders/Orders::num_orders so docs don’t contain broken links or misleading names.

to_sector_indices() only snapshots sector indices; it does not clear the seat’s user_order_sectors. Since this instruction later removes orders from the book, the seat will still point at now-free/reused sectors. Update the flow to also free/clear the mapping (or use an API that both returns indices and marks nodes free) before returning.

The market account in this test is created with data_len = 0 (Account::new(..., 0, ...)), but the on-chain instruction contexts require an initialized market account (header + is_initialized). As written, BatchReplace should fail with AccountNotInitialized. Initialize the market in the test (e.g., run RegisterMarket first or provide valid market data) before asserting success.

OrderSectors::to_sector_indices is documented as removing mapped elements, but it only copies sector indices and takes &self (so it cannot remove/free anything). Either fix the docstring/name to reflect that it’s a read-only snapshot, or change the API to &mut self and actually mark nodes free if the intent is to clear the mapping.

solana-program-log is only referenced behind #[cfg(feature = "debug")] (via the debug! macro), but it’s a required dependency here. Consider making it optional and enabling it via the debug feature to avoid compiling extra deps in non-debug builds.

This code removes orders from the market (remove_at) and sums remaining collateral, but the user’s MarketSeat balances are never credited and the seat’s sector mapping is never cleared. The handler should refund collateral and update the seat/mapping (similar to process_cancel_order) as part of the same atomic instruction.

The handler currently loads the context and then returns Ok(()) without performing any cancels/posts or updating the user's seat. Since BatchReplace is routed from the entrypoint, this will make the instruction succeed while doing nothing; either implement the behavior or return a dedicated error until it’s ready.

Avoid leaving a pub on-chain entrypoint-style function named process_batch_replace_WIP in the program binary. If this is only for experimentation, gate it behind #[cfg(test)]/a feature flag, make it pub(crate), or remove it to prevent accidental use and reduce maintenance overhead.