From 7eede71ad0fc57bd0195b36d49b878a11205f615 Mon Sep 17 00:00:00 2001
From: Pavlo Syrotyna <p.syrotyna@everstake.one>
Date: Tue, 3 Feb 2026 11:18:46 +0200
Subject: [PATCH] feat(blockchain-link): change stake type

---
 packages/blockchain-link-types/src/common.ts  |  9 +++-
 .../blockchain-link-utils/src/blockfrost.ts   | 52 +++++++++++++++----
 2 files changed, 50 insertions(+), 11 deletions(-)

diff --git a/packages/blockchain-link-types/src/common.ts b/packages/blockchain-link-types/src/common.ts
index 008858346d..2ed30a29bb 100644
--- a/packages/blockchain-link-types/src/common.ts
+++ b/packages/blockchain-link-types/src/common.ts
@@ -153,7 +153,12 @@ export interface Transaction {
     ethereumSpecific?: BlockbookTransaction['ethereumSpecific'];
     internalTransfers: InternalTransfer[];
     cardanoSpecific?: {
-        subtype?: 'withdrawal' | 'stake_delegation' | 'stake_registration' | 'stake_deregistration';
+        subtype?:
+            | 'withdrawal'
+            | 'stake_delegation'
+            | 'stake_registration'
+            | 'stake_deregistration'
+            | 'governance_delegation';
         withdrawal?: string;
         deposit?: string;
     };
@@ -314,7 +319,7 @@ export interface SubscriptionAccountInfo {
 
 export type ChannelMessage<T> = T & { id: number };
 
-export type StakeType = 'stake' | 'unstake' | 'claim';
+export type StakeType = 'stake' | 'unstake' | 'claim' | 'change-delegate';
 
 export type TokenDetailByMint = {
     [mint: string]: {
diff --git a/packages/blockchain-link-utils/src/blockfrost.ts b/packages/blockchain-link-utils/src/blockfrost.ts
index f7ef37c7ad..a6be175ab6 100644
--- a/packages/blockchain-link-utils/src/blockfrost.ts
+++ b/packages/blockchain-link-utils/src/blockfrost.ts
@@ -50,18 +50,47 @@ const hexToString = (input: string): string => {
     return str;
 };
 
-const getSubtype = (tx: Pick<BlockfrostTransaction, 'txData'>) => {
-    const withdrawal = tx.txData.withdrawal_count > 0;
+const getSubtype = (
+    tx: Pick<BlockfrostTransaction, 'txData'>,
+    totalInput: BigNumberValue,
+    totalOutput: BigNumberValue,
+    allOutputsAreChange: boolean,
+) => {
+    const { withdrawal_count, stake_cert_count, delegation_count, deposit, fees } = tx.txData;
+
+    const withdrawal = withdrawal_count > 0;
     if (withdrawal) {
         return 'withdrawal';
     }
 
-    const registrations = tx.txData.stake_cert_count;
-    const delegations = tx.txData.delegation_count;
-    if (registrations === 0 && delegations === 0) return;
+    // governance_delegation is detected heuristically.
+    // Blockfrost txData does not expose governance (DRep) certificates, so we infer it as:
+    // - no withdrawals
+    // - no stake or pool delegation certificates
+    // - zero deposit
+    // - self transaction where totalInput === totalOutput + fee
+    // - all outputs go to change addresses (no value transfer)
+    // - non-zero fee
+    // This may still misclassify rare fee-only self transactions.
+    if (
+        withdrawal_count === 0 &&
+        stake_cert_count === 0 &&
+        delegation_count === 0 &&
+        new BigNumber(deposit || 0).isZero()
+    ) {
+        const fee = new BigNumber(fees || 0);
+        const isFeeOnly =
+            fee.gt(0) && new BigNumber(totalInput).eq(new BigNumber(totalOutput).plus(fee));
 
-    if (registrations > 0) {
-        if (new BigNumber(tx.txData.deposit).gt(0)) {
+        if (isFeeOnly && allOutputsAreChange) {
+            return 'governance_delegation';
+        }
+    }
+
+    if (stake_cert_count === 0 && delegation_count === 0) return;
+
+    if (stake_cert_count > 0) {
+        if (new BigNumber(deposit).gt(0)) {
             // transaction could both register staking address and delegate stake at the same time. In that case we treat it as "stake registration"
             return 'stake_registration';
         }
@@ -69,7 +98,7 @@ const getSubtype = (tx: Pick<BlockfrostTransaction, 'txData'>) => {
         return 'stake_deregistration';
     }
 
-    if (delegations > 0) {
+    if (delegation_count > 0) {
         return 'stake_delegation';
     }
 };
@@ -225,6 +254,11 @@ export const transformTransaction = (
     const internal = accountAddress ? filterTargets(accountAddress.change, outputs) : [];
     const totalInput = inputs.reduce(sumVinVout, 0);
     const totalOutput = outputs.reduce(sumVinVout, 0);
+    const allOutputsAreChange =
+        fullData &&
+        blockfrostTxData.txUtxos.outputs.every(o =>
+            accountAddress?.change.some(c => c.address === o.address),
+        );
 
     if (outgoing.length === 0 && incoming.length === 0) {
         type = 'unknown';
@@ -295,7 +329,7 @@ export const transformTransaction = (
         tokens,
         internalTransfers: [],
         cardanoSpecific: {
-            subtype: getSubtype(blockfrostTxData),
+            subtype: getSubtype(blockfrostTxData, totalInput, totalOutput, allOutputsAreChange),
             withdrawal,
             deposit,
         },