Migration and External AMM

Atomic migration on the final curve purchase, USDC precision conversion, LP locking, donation boundaries, and external constant-product pricing.

Once internal-market Token sale inventory reaches zero, BigShortProtocol-EVM establishes external liquidity using reserved Token + the curve's actual net USDC reserves and starts that Token's independent Short Engine. Migration does not use virtual USDC, mix in funds from other Token curves, or use lending reserves as initial external liquidity.

1. Trigger and Execution Order

2. From native18 to Six-Decimal ERC-20 USDC

Native Arc USDC balances and the external-market USDC ERC-20 interface represent the same quote asset with different precisions. The current code uses:

Let actual USDC reserves to migrate be $Q_{18}$:

Here, $Q_6$ is the number of smallest ERC-20 USDC units transferred into the Pair, and $D$ is a remainder below 0.000001 USDC. The contract neither rounds this remainder up nor silently includes it in Pair reserves.

Ownership of Migration Remainders

Migration removes this curve's full $Q_{18}$ from total liabilities for all unmigrated curves while adding remainder liability $D$. Other Token curves' reserves are not reduced by this migration.

3. Full-Scale Curve-Completion Example and Three Valuations

Example D: Buying All Initial Inventory at Once, without Tax or Donations

to buy all 793,100,000 Token. Net USDC entering the curve is:

These are one-shot examples with a defined initial baseline, not a promise that every sequence of buys and sells accumulates exactly the same smallest-unit result. Per-trade integer rounding and the exact-budget entry point can produce differences.

Distinguish the Curve Endpoint, Actual External Values, and Ideal Anchors

The actual initial external-market price is approximately 0.000058779281628806186564 USDC/Token. Current parameters do not enforce exact smallest-unit continuity of marginal prices across migration; internal virtual reserves and actual migration reserves are distinct values.

Fixed ideal anchors provide a reproducible risk-model baseline; actual Pair reserves determine spot prices, debt buyback costs, and every executed swap. Do not describe the model parameter 12,161.433370 USDC as funds that every migration must receive.

4. Pair Pre-Creation, Donations, and Contamination Protection

Which Pre-Existing States Are Accepted?

At the start of migration:

• The Pair's Token reserve must be 0.
• The Pair's actual Token balance must be 0.
• Total LP supply must be 0; previously issued LP held by others must not exist.
• The Pair's USDC reserve must not exceed its actual USDC balance.
• Pair address, constituent tokens, associated venue, and code identity must pass Profile validation.

After migration transfers, the actual USDC increase is checked. After LP minting, the Token reserve must equal the migration allocation, and the USDC reserve must equal actual USDC balance before migration + USDC added in this migration. A mismatch triggers PairContaminated or the applicable validation error and reverts.

Checking a configuration snapshot goes beyond checking a version number. Migration revalidates code hashes and relationships for the Engine deployer, Engine implementation, and venue Factory/Router, checks the Engine parameter hash and Oracle configuration, derives the expected Pair address from its initialization code hash, and validates the actual Pair through its runtime code hash. If deployer or implementation runtime code differs from the registered value, the final buy reverts atomically instead of silently using the changed implementation.

These rules do not guarantee acceptance of donations of any size; integer reserve ranges, LP minting, and other execution constraints still apply. Donations not yet recorded in reserves may also be removed by normal Pair operations before migration, so the balance at execution is what matters.

Where Do Donations Go?

Let the pre-existing USDC balance at migration be $Q_{\mathrm{pre},6}$:

The curve still adds a fixed 206,900,000 Token. USDC donations retained at migration enter the actual pool, with no refund to the donor or final buyer. They raise the actual starting price and actualStartMarketCap, do not rewrite the fixed ideal migration anchors. A high-price donation at migration does not immediately complete time-weighted capacity release either.

Example E: Retaining an Extra 170 USDC in Example D's Main Pair

Transferring USDC directly to the Factory is different: it does not automatically increase a Token's realNativeReserves and therefore does not automatically become that Token's migration funds. Distinguish curve ledger balances, the Factory's total balance, and actual Pair balances.

5. Final Destinations of LP and Lending Inventory

Ordinary Holders Cannot Redeem Any Initial LP

It also requires LP minted in this operation to be greater than 0 and total LP to exceed the liquidity amount returned by this call, accounting for V2's initial minimum-liquidity structure. Neither the creator, operators, protocol wallets, nor the final buyer receives this migration LP.

Here, burning LP means LP is held by the zero address and cannot be retrieved and redeemed by ordinary accounts; it does not mean ERC-20 Total supply becomes 0, nor that Token in the Pair is burned. The migration check concerns the initial instant and does not establish that liquidity can never be added or other LP minted in the external AMM later.

Lending Reserves Remain Independent

The predicted Engine address already holds 199,861,071 Token. Migration only deploys and initializes the Engine; it does not mint again or transfer this principal into the Pair. Initialization reads actual Pair reserves and tracks available lending principal in a separate ledger.