Merge #7342: fix(rpc): report inactive DIP3 for ProTx RPCs

f671673 fix: use token reject reason for inactive DIP3 (PastaClaw)
4d38776 fix(rpc): report inactive DIP3 for ProTx RPCs (PastaClaw)

Pull request description:

  ## Issue being fixed or feature implemented

  ProTx RPCs can return a generic `bad-tx-type` error with RPC code `-1` when
  used before DIP0003 is active on regtest/devnet. The underlying problem is that
  special transaction validation rejects extra payload transactions before DIP3,
  but the RPC response does not explain that activation height is the blocker.

  This improves the Dash Core developer experience by returning an explicit
  inactive-DIP3 RPC verification error with activation height context.

  ## What was done?

  - Added an early DIP0003 activation check in the shared ProTx submission helper
    before special transaction validation.
  - Return `RPC_VERIFY_ERROR` with the DIP3 activation height, current chain
    height, next block height, and a regtest/devnet hint.
  - Added functional test coverage for both funded and external-collateral ProTx
    registration paths before DIP3 activation.

  ## How Has This Been Tested?

  Tested locally on macOS arm64 with the existing depends prefix and autotools
  build.

  - `make -j8 src/dashd src/dash-cli`
  - `test/functional/feature_dip3_deterministicmns.py --cachedir=/Users/claw/Projects/dash/worktrees/protx-dip3-error/test/cache`
  - Pre-PR review gate: `ship`

  ## Breaking Changes

  None. This only changes the RPC error returned before DIP0003 activation for
  ProTx submission paths.

  ## Checklist:

  - [x] I have performed a self-review of my own code
  - [ ] I have commented my code, particularly in hard-to-understand areas
  - [x] I have added or updated relevant unit/integration/functional/e2e tests
  - [ ] I have made corresponding changes to the documentation
  - [ ] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_

ACKs for top commit:
  UdjinM6:
    utACK f671673
  PastaPastaPasta:
    utACK f671673

Tree-SHA512: 0667d9d4860947c09849257bbf6585456ad4aeff7a6c6295de5ca1fc8c729909ac50af960697466697439952b54e1fd3ddaa972a31ef94a120a711b37faf8b25

Author: PastaPastaPasta

src/evo/specialtxman.cpp

@@ -110,7 +110,7 @@ static bool CheckSpecialTxInner(CDeterministicMNManager& dmnman, llmq::CQuorumSn
         return true;
 
     if (!DeploymentActiveAfter(pindexPrev, chainman.GetConsensus(), Consensus::DEPLOYMENT_DIP0003)) {
-        return state.Invalid(TxValidationResult::TX_BAD_SPECIAL, "bad-tx-type");
+        return state.Invalid(TxValidationResult::TX_BAD_SPECIAL, "bad-tx-type-dip3-inactive");
     }
 
     try {

src/rpc/evo.cpp

@@ -354,8 +354,25 @@ static std::string SignAndSendSpecialTx(const JSONRPCRequest& request, CChainsta
     {
     LOCK(::cs_main);
 
+    const CBlockIndex* tip{chainman.ActiveChain().Tip()};
+    const Consensus::Params& consensus_params{chainman.GetConsensus()};
+    if (!DeploymentActiveAfter(tip, consensus_params, Consensus::DEPLOYMENT_DIP0003)) {
+        const int current_height{tip ? tip->nHeight : -1};
+        const int next_block_height{current_height + 1};
+        const int activation_height{consensus_params.DIP0003Height};
+        const int blocks_to_mine{
+            activation_height > next_block_height ? activation_height - next_block_height : 0
+        };
+        throw JSONRPCError(RPC_VERIFY_ERROR, strprintf(
+            "DIP0003 is not active yet; ProTx transactions are valid starting at block height %d "
+            "(current chain height %d, next block height %d). Mine %d more block%s or restart "
+            "this regtest/devnet chain with DIP3 activation parameters that are already active.",
+            activation_height, current_height, next_block_height, blocks_to_mine,
+            blocks_to_mine == 1 ? "" : "s"));
+    }
+
     TxValidationState state;
-    if (!chain_helper.special_tx->CheckSpecialTx(CTransaction(tx), chainman.ActiveChain().Tip(), chainman.ActiveChainstate().CoinsTip(), true, state)) {
+    if (!chain_helper.special_tx->CheckSpecialTx(CTransaction(tx), tip, chainman.ActiveChainstate().CoinsTip(), true, state)) {
         throw std::runtime_error(state.ToString());
     }
     } // cs_main

test/functional/feature_dip3_deterministicmns.py

@@ -62,12 +62,43 @@ def run_test(self):
         self.log.info("testing rejection of ProTx before dip3 activation")
         assert self.nodes[0].getblockchaininfo()['blocks'] < 135
 
+        def dip3_inactive_error():
+            current_height = self.nodes[0].getblockcount()
+            next_block_height = current_height + 1
+            blocks_to_mine = 135 - next_block_height
+            return (
+                f"DIP0003 is not active yet; ProTx transactions are valid starting at block height 135 "
+                f"(current chain height {current_height}, next block height {next_block_height}). "
+                f"Mine {blocks_to_mine} more block{'s' if blocks_to_mine != 1 else ''} or restart "
+                "this regtest/devnet chain with DIP3 activation parameters that are already active."
+            )
+
+        before_activation_mn: MasternodeInfo = self.prepare_mn(
+            self.nodes[0], self.num_initial_mn + 2, 'mn-before-dip3-activation'
+        )
+        self.nodes[0].sendtoaddress(
+            before_activation_mn.fundsAddr, before_activation_mn.get_collateral_value() + 0.001
+        )
+        before_activation_mn.register_fund(
+            self.nodes[0],
+            submit=True,
+            expected_assert_code=-25,
+            expected_assert_msg=dip3_inactive_error(),
+        )
+
         mns: List[MasternodeInfo] = []
 
         # prepare mn which should still be accepted later when dip3 activates
         self.log.info("creating collateral for mn-before-dip3")
         before_dip3_mn: MasternodeInfo = self.prepare_mn(self.nodes[0], 1, 'mn-before-dip3')
         self.create_mn_collateral(self.nodes[0], before_dip3_mn)
+        self.nodes[0].sendtoaddress(before_dip3_mn.fundsAddr, 0.001)
+        before_dip3_mn.register(
+            self.nodes[0],
+            submit=True,
+            expected_assert_code=-25,
+            expected_assert_msg=dip3_inactive_error(),
+        )
         mns.append(before_dip3_mn)
 
         # block 150 starts enforcing DIP3 MN payments