Merge pull request #6 from uma-universal-money-address/feat/conversti…

…ondetails

Tweak conversion mechanics to be more explicit and safe.

uma-sdk/src/commonMain/kotlin/me/uma/Version.kt

@@ -6,7 +6,7 @@ import kotlinx.serialization.json.encodeToJsonElement
 import kotlinx.serialization.json.put
 
 const val MAJOR_VERSION = 0
-const val MINOR_VERSION = 1
+const val MINOR_VERSION = 2
 const val UMA_VERSION_STRING = "$MAJOR_VERSION.$MINOR_VERSION"
 
 /**

uma-sdk/src/commonMain/kotlin/me/uma/protocol/Currency.kt

@@ -26,7 +26,7 @@ data class Currency @JvmOverloads constructor(
      * Estimated millisats per smallest "unit" of this currency (eg. 1 cent in USD).
      */
     @SerialName("multiplier")
-    val millisatoshiPerUnit: Long,
+    val millisatoshiPerUnit: Double,
 
     /**
      * Minimum amount that can be sent in this currency. This is in the smallest unit of the currency
@@ -41,13 +41,16 @@ data class Currency @JvmOverloads constructor(
     val maxSendable: Long,
 
     /**
-     * Number of digits after the decimal point for display on the sender side. For example,
-     * in USD, by convention, there are 2 digits for cents - $5.95. in this case, `decimals`
-     * would be 2. Note that the multiplier is still always in the smallest unit (cents). This field
-     * is only for display purposes. The sender should assume zero if this field is omitted, unless
-     * they know the proper display format of the target currency.
+     * The number of digits after the decimal point for display on the sender side, and to add clarity
+     * around what the "smallest unit" of the currency is. For example, in USD, by convention, there are 2 digits for
+     * cents - $5.95. In this case, `decimals` would be 2. Note that the multiplier is still always in the smallest
+     * unit (cents). In addition to display purposes, this field can be used to resolve ambiguity in what the multiplier
+     * means. For example, if the currency is "BTC" and the multiplier is 1000, really we're exchanging in SATs, so
+     * `decimals` would be 8.
+     *
+     * For details on edge cases and examples, see https://github.com/uma-universal-money-address/protocol/blob/main/umad-04-lnurlp-response.md.
      */
-    val decimals: Int? = null,
+    val decimals: Int,
 ) {
     fun toJson() = Json.encodeToString(this)
 }