[$45 BOUNTY] [Go] Add WebSocket order book delta validation tests

[Peter7896]

Bounty: $45 (LT)

Area: market/ws, market/orderbook, market/matching

Current state: Order book snapshot recovery is covered, but there is no focused deterministic coverage for malformed, stale, or out-of-order WebSocket order book deltas and the state-preservation behavior around those failures.

What's needed: Add tests or helpers that validate WebSocket order book delta handling without requiring live services.

Acceptance criteria:

• Reject malformed bid/ask price, quantity, side, or symbol payloads with a clear error.
• Reject stale or out-of-order sequence updates without mutating the existing order book state.
• Preserve the current book after an invalid delta or checksum-style mismatch is encountered.
• Cover a valid snapshot followed by valid deltas so the recovery path and live update path are tested together.
• Keep the coverage deterministic on Windows and Unix-like hosts.

Required validation:

• Run go test ./market/orderbook ./market/matching ./market/ws where the Go toolchain is available
• Run python3 build.py
• Include the generated diagnostic .logd artifact from diagnostic/build-XXX.logd; also include diagnostic/build-XXX.json if present
• Use .github/pull_request_template.md for your submission

Tracker note: This issue is opened for the upstream LT bounty tracker; bounty eligibility and payout are determined by upstream review, merge, and tracker rules.

[fengyangxxx]

/attempt #4

[Peter7896]

Thanks for the attempt. I can see the candidate PR on this fork now.

For this bounty tracker issue, please keep the work linked to this issue and make sure the PR stays narrowly scoped to the WebSocket/order book delta validation area. Before I can forward anything for upstream bounty review, the PR needs to include the exact script-generated diagnostic pair from python3 build.py (diagnostic/build-*.json plus the matching diagnostic/build-*.logd) and avoid hand-edited diagnostic output.

If the PR only targets this fork, an upstream PR against lobster-trap/Kickama will still be needed for merge and payout review. I cannot assign or guarantee payment directly from this issue.

[BERT70293]

I'd like to work on this bounty. PR submitted: #6

Changes:

• Added Delta type with ValidateDelta and ApplyDelta to orderbook package
• Rejects malformed prices, quantities, sides, symbols, and stale/out-of-order sequences
• Preserves order book state on all invalid inputs
• Covers valid snapshot → delta recovery path
• Comprehensive tests for market/orderbook, market/matching, market/ws
• All tests deterministic, no live services required

@Peter7896 please review when you have a chance!