Expose RandomX seed in getblocktemplate

src/rpc/mining.cpp

@@ -863,6 +863,10 @@ static RPCHelpMan getblocktemplate()
                 {RPCResult::Type::NUM_TIME, "curtime", "current timestamp in " + UNIX_EPOCH_TIME},
                 {RPCResult::Type::STR, "bits", "compressed target of next block"},
                 {RPCResult::Type::NUM, "height", "The height of the next block"},
+                {RPCResult::Type::NUM, "pow_algo_id", "Mining algorithm id: 0 for SHA256D, 1 for RandomX"},
+                {RPCResult::Type::STR, "pow_algo", "Mining algorithm name: sha256d or randomx"},
+                {RPCResult::Type::NUM, "randomx_seed_height", /* optional */ true, "Height of the block used as the RandomX seed source"},
+                {RPCResult::Type::STR_HEX, "randomx_seed", /* optional */ true, "RandomX seed key in raw uint256 byte order"},
                 {RPCResult::Type::STR, "default_witness_commitment", /* optional */ true, "a valid witness commitment for the unmodified block template"},
             }},
         },
@@ -1212,6 +1216,31 @@ static RPCHelpMan getblocktemplate()
     result.pushKV("bits", strprintf("%08x", pblock->nBits));
     result.pushKV("height", (int64_t)(pindexPrev->nHeight+1));
 
+    result.pushKV("pow_algo_id", algo);
+    result.pushKV("pow_algo", GetMiningAlgoName(algo));
+
+    if (algo == ALGO_RANDOMX) {
+        const int blockHeight = pindexPrev->nHeight + 1;
+        const int seedHeight =
+            GetRandomXSeedHeight(blockHeight, consensusParams);
+
+        uint256 randomxSeed;
+        if (!GetRandomXSeed(
+                pindexPrev,
+                blockHeight,
+                consensusParams,
+                randomxSeed)) {
+            throw JSONRPCError(
+                RPC_INTERNAL_ERROR,
+                "Failed to resolve RandomX seed");
+        }
+
+        result.pushKV("randomx_seed_height", seedHeight);
+        result.pushKV(
+            "randomx_seed",
+            HexStr(MakeUCharSpan(randomxSeed)));
+    }
+
     if (consensusParams.signet_blocks) {
         result.pushKV("signet_challenge", HexStr(consensusParams.signet_challenge));
     }

test/functional/mining_randomx_gbt.py

@@ -56,6 +56,10 @@ class RandomXGetBlockTemplateTest(DigiByteTestFramework):
             sha_template["version"] & BLOCK_VERSION_ALGO,
             BLOCK_VERSION_SHA256D,
         )
+        assert_equal(sha_template["pow_algo_id"], 0)
+        assert_equal(sha_template["pow_algo"], "sha256d")
+        assert "randomx_seed_height" not in sha_template
+        assert "randomx_seed" not in sha_template
 
         self.log.info("Mining RPC reports only SHA256D before activation")
         mining_info = node.getmininginfo()
@@ -130,6 +134,14 @@ class RandomXGetBlockTemplateTest(DigiByteTestFramework):
             randomx_template["version"] & BLOCK_VERSION_ALGO,
             BLOCK_VERSION_RANDOMX,
         )
+        assert_equal(randomx_template["pow_algo_id"], 1)
+        assert_equal(randomx_template["pow_algo"], "randomx")
+        assert_equal(randomx_template["randomx_seed_height"], 0)
+
+        genesis_hash = node.getblockhash(0)
+        expected_randomx_seed = bytes.fromhex(genesis_hash)[::-1].hex()
+        assert_equal(randomx_template["randomx_seed"], expected_randomx_seed)
+        assert_equal(len(randomx_template["randomx_seed"]), 64)
 
         self.log.info("Default GBT remains SHA256D after RandomX activation")
         sha_template = node.getblocktemplate(NORMAL_GBT_REQUEST_PARAMS)
@@ -138,6 +150,10 @@ class RandomXGetBlockTemplateTest(DigiByteTestFramework):
             sha_template["version"] & BLOCK_VERSION_ALGO,
             BLOCK_VERSION_SHA256D,
         )
+        assert_equal(sha_template["pow_algo_id"], 0)
+        assert_equal(sha_template["pow_algo"], "sha256d")
+        assert "randomx_seed_height" not in sha_template
+        assert "randomx_seed" not in sha_template
 
         self.log.info("Mining RPC exposes SHA256D and RandomX at activation")
         mining_info = node.getmininginfo()