[moodysalem]

Board origin and outcome

• Board origin: EKU-946, ancestor EKU-928.
• Integration parent: EKU-1023.
• Delivery owner/task: EKU-1577.
• User outcome: exact MEVCapture v2.1 quotes, with v1 behavior unchanged.
• Contract authority: da368348238a46857d39b6db57bdb2b432c979df, design rev6 ad3e6585-8135-431e-82af-7a177d7f5282.

What this adds

src/quoting/pools/mev_capture_v21.rs is a separate module. The v1 mev_capture.rs is unchanged. Base is rust-sdk 32af207, and no launchpad or auction work is included.

• Typed inputs. MevCaptureV21Config is the exact getConfig tuple and is validated against the constructor. MevCaptureV21Anchor holds all seven getAnchor fields. MevCaptureV21PoolKey carries the contract Q0.16 fee and tick_spacing_exp.
• MevCaptureV21Pool::new(key, config, state, sorted_ticks). Implements Pool (Meta = BlockTimestamp).
• simulate_swap(state, MevCaptureV21SwapParams { is_token1, amount, sqrt_ratio_limit, min_fee, skip_ahead }, now). Returns:
  • the gate result
  • one record per Core call: kind (pass-through, toward or away k), limit, minFee, remaining amount, deltas, state after, steps and ticks crossed
  • checked int128 sums, the final pool and anchor state, and resources (Core calls and steps, ticks crossed, anchor updates, state writes)
• Contract semantics covered:
  • first-touch gate and Q1 restore
  • toward call at the user minFee, ending at floor or ceil of the anchor
  • N1 sliver
  • absolute-grid and doubling away segments, with membership decided by sqrt ratio
  • per-call fee of max(segmentFee, userMinFee); Core also takes the max with the pool fee
  • user limit, early stop and the maxSegments budget
  • post-swap refresh, suppressed when a position changed in the same timestamp
• Core step loop emulation. The v2.1 Core step loop is emulated: initialized ticks, 256-spacing word ends, skipAhead and Core's stored tick. Every step rounds its fee separately, so this matters for exact amounts. Step math is the SDK's compute_step::<Evm> with fee << 48.

Evidence (zero differences, inputs only)

• swaps.json (merged contract): 32 swaps / 152 Core calls. Each swap checks gate, every call (limit, minFee, remaining amount, in order), both deltas, pool sqrt ratio/tick/liquidity and all seven anchor fields. Pool::quote is also checked against the same result.
• New vectors generated from the unmodified merged contract: the generator is in tests/data/mevcapture-v21/generator, and in the same environment the merged generator reproduced swaps.json byte for byte.
  • swapsSupplement.json (9 / 61) covers word-boundary step splits with liquidity, user minFee on away segments, and the refresh raise and its suppression.
  • swapsNondefault.json (6 / 10) covers a nondefault config, decay clamp, capped segments and a pass-through swap.
• Earlier replays still pass: 120 anchor updates, 24 scenarios / 1785 gate steps, 288 schedules, nondefault model test, construction and revert checks.
• Mutation checks: each of these mutants fails the replay: removed sqrt-ratio skip, ignored minFee (Core or away), removed refresh, no word-end stops, toward call without early stop, ignored pool fee. Two survivors are equivalent or unreachable: the maxSegments budget clause (fee reaches maxFee first, by the constructor's budget lemma) and the int128 output clamp at 2^127.
• Commands: cargo test --features evm,starknet,serde (193 lib + 8 v2.1 tests); cargo fmt --check; CI clippy with and without no_std, -D warnings; no_std,evm build. The existing 9 v1 tests pass.
• Representation: contract fees are Q0.16 and fee_q16_to_q64 is lossless. Sqrt ratios are 64.128 fixed values that are exactly representable as compressed SqrtRatio, and the replay checks the round trip.

Known limits

• Quotes are exact for the initialized ticks supplied. If a swap reaches ticks outside the fetched range, those ticks are needed too.
• Pool::quote uses minFee 0 and skipAhead 0. Use simulate_swap for other values.

No publish, deployment, migration, activation, extension address or monitoring claim. CTO owns ordinary review and merge, and launch and deployment holds remain.