fix(cross2eth): reuse broadcast lock tx on ebcli retry to prevent double mint

[33cn]

Context

ci_cross2eth failed on run https://github.com/33cn/plugin/actions/runs/33836471133/job/100909914007?pr=1312 (branch fix-token-duplicate-finishcreate), while the pull_request run of the same commit passed — a timing flake, not a regression from that PR.

Failure: TestETH2Chain33USDT_proxy_excess (BSC side) — after a single ethereum lock -m 100, the bridge bank balance went 140 → 340 (expected 240). Two locks executed.

Root cause

ebcli's sync lock command retries the whole Manager.LockEthErc20Asset rpc up to 3 times on error (commit 857c01f). The flow is not idempotent (approve + lock txs). In the failing run the first attempt's Lock tx was broadcast/mined but the handler reported a transient error (26s wall time fits a send-stage rpc error: ~10s attempt 1 + 0.5s retry sleep + ~15s attempt 2), so the retry re-executed the lock — locking the same asset twice on ETH/BSC and minting 2x on the chain33 side.

Fix

Make the sync lock idempotent across retries in the ebrelayer:

• ethtxs.LockEthErc20Asset now returns LockBroadcastError carrying the tx hash at the two post-broadcast error points (lock send error with non-nil tx, and receipt-wait failure).
• New ethtxs.WaitLockTxConfirmed waits for a recorded tx and distinguishes confirmed-success / confirmed-failed (ErrLockTxFailed) / still-pending (ErrLockTxPending).
• manager.LockEthErc20Asset records broadcast lock txs keyed by chain+owner+token+amount+receiver (10min TTL, swept on write). On retry with the same params it waits for the recorded tx instead of re-locking; only a definitively reverted tx is re-executed.

This also protects against the rpc-reply-lost-after-success case, at the cost of an idempotency window: an identical lock request within the TTL returns the first tx hash.

Tests

• New Test_WaitLockTxConfirmedAndBroadcastError in ethtxs (simulator): wait-on-recorded-hash returns the same hash; LockBroadcastError carries the hash via errors.As.
• go test ./plugin/dapp/cross2eth/ebrelayer/... all pass.
• ci_cross2eth (docker e2e, ~40min) is the end-to-end verification.

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