# Stage: PMM Selection & Failure Handling

The `SELECT_PMM` stage follows after the `MPC` confirms the deposit. At this point, the `Solver` chooses the optimal `PMM` (Professional Market Maker) based on the user's `RFQ` constraints. If a valid `PMM` isn't matched before `scriptTimeout`, the trade is marked as `FAILURE`.

#### <mark style="color:orange;">Key Responsibilities</mark>

* **PMM Selection:** Choose a `PMM` offering a valid quote based on `minAmountOut`.
* **Quote Verification:** Confirm the quote is valid and linked to a pre-signed settlement.
* **Proof Submission:** Submit signed data from both parties to validate the trade terms.
* **Fee Policy Compliance:** Ensure fees align with the user's expectations.

#### <mark style="color:orange;">Scenarios</mark>

* **Successful PMM Selection:**
  * The protocol validates the PMM's data, locks fees, emits a `SelectedPMM` event, and advances to `MAKE_PAYMENT`.
* **No Match/Timeout:**
  * If no PMM is selected within `scriptTimeout`, the trade is stalled. It may be marked as `Failure`, eligible for refund, and no payment occurs.

#### <mark style="color:orange;">Function Descriptions</mark>

* **`selectPMM(tradeId, info)`**:
  * Executable only by the authorized `Solver` through the `Router`.
  * Validates the stage, timeout, fees, and signatures.
* **`report(tradeId, msgError, signature)`**:
  * Executable only by authorized `MPC Node`.
  * The trade transitions to `FAILURE`, enabling refunds after timeout.

#### <mark style="color:orange;">Refund and Query</mark>

* Post `SELECT_PMM`, query functions track trade status:
  * **For Success:** Use `getCurrentStage` to confirm advancement, `getPMMSelection` for selection data.
  * **For Failure:** Use `getCurrentStage` to confirm failure, `getFailureInfo` for error details.


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