fix(twap-monitor): skip submit_order when submitted:{uid} already in store (COW-1085)

[brunota20]

What this PR does

Short-circuit submit_ready when submitted:{uid} is already in local-store, so a TWAP child that succeeded on a prior poll-tick does not get re-submitted on the next block. Fixes the DuplicatedOrder Warn observed in the 2026-06-23 Sepolia soak (see COW-1085 for the live evidence).

Why

composable.getTradeableOrderWithSignature returns Ready whenever the conditional order has a valid (sell, buy) tuple for the current block. It does not know shepherd has already POSTed the resulting child to the orderbook. The strategy already wrote submitted:{uid} after a successful submit, but the next poll-tick polled the chain and submitted again, producing a wasted orderbook call and a misleading Warn.

The Warn dispatch itself is correct (Drop, no retry storm), so the consequence is bounded — but on a 7-day soak (COW-1031) with N TWAPs × K children, this becomes N×K spurious Warn lines that operators have to learn to ignore.

Change

1. compute_uid_hex(chain_id, order, owner) helper — computes the canonical 56-byte UID deterministically from on-chain inputs via OrderData::uid(domain, owner). Mirrors what the orderbook derives server-side from the signed payload.
2. Idempotency check at top of submit_ready — looks up submitted:{uid} and short-circuits with an Info log before any network work (no appData GET, no submit_order).
3. Marker key now uses the client-computed UID instead of the server-returned UID, so the read and write paths agree. In production the two values are the same canonical derivation; a divergence (e.g. a mock orderbook returning a stub UID, or a real protocol drift) now triggers a Warn (twap UID divergence: client=… server=…).

Tests (24 total, all green)

• Updated poll_ready_submits_order_and_persists_submitted_uid and poll_ready_resolves_non_empty_app_data_then_submits: previously hardcoded submitted:0xfeedface against the MockHost's stub UID; now compute the expected key via compute_uid_hex(SEPOLIA, &ready_order, owner). Both also assert the divergence Warn fires (since 0xfeedface is not the canonical UID).
• New poll_ready_skips_submit_when_submitted_uid_already_in_store: seeds the marker, dispatches a block, asserts chain.call_count() == 1 (poll still happens), cow_api.call_count() == 0 (no submit), cow_api.request_calls().len() == 0 (no appData GET), and the Info log line appears verbatim.

running 24 tests
test result: ok. 24 passed; 0 failed; 0 ignored

cargo clippy -p twap-monitor --all-targets -- -D warnings clean. cargo fmt --check clean. cargo build -p twap-monitor --target wasm32-wasip2 --release clean.

Live validation

The fix is not yet on the soak VM; deploy after review. Expected post-deploy behaviour:

• Each successful TWAP child submit produces exactly one submitted {uid} Info line.
• Subsequent poll-ticks for the same child in the same validity window produce one twap {uid} already submitted; skipping poll re-submit Info line and no orderbook calls.
• Zero DuplicatedOrder Warn lines for the lifecycle-correct path.

Linear

Resolves COW-1085.

AI assistance disclosure: drafted by Claude (Opus 4.7, 1M context) following the 2026-06-23 soak inspection.

[linear-code]

COW-1085

[brunota20]

Live validation note (2026-06-23 14:00 UTC)

Combined with the rest of the redesign + fix bundle on deploy/cow-1076-observe-on-m5 and deployed to the Sepolia soak VM. Container Up healthy with the new image since 13:56:50 UTC. Will accumulate live evidence in the next observation window.

Companion PRs (same redesign / soak deploy bundle)

PR	Concern	Layer
#62	ethflow-watcher: observe + verify (replaces submit)	M2 (BLEU-833 alternative)
#63	ethflow-watcher: same redesign with BLEU-855 split	M3/M4 (COW-1074 base)
#64	twap-monitor: skip submit on already-submitted UID	M5 (COW-1085)
#65	nexum-engine: gap-closed log on alloy-internal reconnect	M5 (COW-1086)

Each is single-concern; the deploy branch is the cumulative integration point and will fold into latest once the stack lands.

[brunota20]

Superseded by deploy branch commit 94eff8b fix(twap-monitor): skip submit_order when submitted:{uid} already in store (COW-1085) (now in dev/m5-base). Closing as merged via different commit.