Probe target
  npm package: @evolution-sdk/evolution
  version: 0.5.12
  install command:
    npm install --prefix handoffs/evolution-probe --ignore-scripts \
      --no-audit --no-fund @evolution-sdk/evolution@0.5.12
  result: exit 0, 39 packages installed

The package was inspected through its shipped TypeScript declarations. A
provider-free payment fixture was not available, so P1 uses API-surface evidence.

Inspected members
  dist/sdk/builders/TransactionBuilder.d.ts
    Phase = "selection" | "changeCreation" | "feeCalculation" | "balance" |
            "evaluation" | "collateral" | "fallback" | "complete"
    PhaseContext includes calculatedFee and changeOutputs, but is internal phase
    state rather than a public builder callback.
    payToAddress(params: PayToAddressParams)
    build(options?: BuildOptions)
    Each build() creates fresh state; repeated calls are independent.
  dist/sdk/builders/operations/Operations.d.ts
    PayToAddressParams has fixed address and assets fields.
  dist/sdk/builders/TransactionResult.d.ts
    toTransaction(): Promise<Transaction>
    estimateFee(): Promise<bigint>
    Both are available on the result returned after build completes.
  dist/sdk/builders/RedeemerBuilder.d.ts
    SelfRedeemerFn = (input: IndexedInput) => Data
    BatchRedeemerFn = (inputs: ReadonlyArray<IndexedInput>) => Data
    IndexedInput contains only final input index and original UTxO, not fee,
    outputs, or the assembled transaction.

Conclusion
  Plain fee/change balancing is part of build(). Fee-dependent outputs and a
  final-output-dependent redeemer require an outer build -> inspect -> rebuild
  loop. There is no public in-build final-transaction observation/re-entry hook.