feat: add P2MR fixed-script wallet integration

packages/wasm-utxo/js/fixedScriptWallet/chains.ts

@@ -8,7 +8,7 @@ import { FixedScriptWalletNamespace } from "../wasm/wasm_utxo.js";
 import type { OutputScriptType } from "./scriptType.js";
 
 /** All valid chain codes as a const tuple */
-export const chainCodes = [0, 1, 10, 11, 20, 21, 30, 31, 40, 41] as const;
+export const chainCodes = [0, 1, 10, 11, 20, 21, 30, 31, 40, 41, 360, 361] as const;
 
 /** A valid chain code value */
 export type ChainCode = (typeof chainCodes)[number];

packages/wasm-utxo/src/address/networks.rs

@@ -142,6 +142,7 @@ impl OutputScriptSupport {
             OutputScriptType::P2sh => true, // all networks support legacy scripts
             OutputScriptType::P2shP2wsh | OutputScriptType::P2wsh => self.segwit,
             OutputScriptType::P2trLegacy | OutputScriptType::P2trMusig2 => self.taproot,
+            OutputScriptType::P2mr => self.p2mr,
         }
     }
 }

packages/wasm-utxo/src/bip322/bitgo_psbt.rs

@@ -140,6 +140,9 @@ pub fn add_bip322_input(
                 create_bip32_derivation(wallet_keys, chain, index);
             inner_psbt.inputs[input_index].witness_script = Some(script.witness_script.clone());
         }
+        WalletScripts::P2mr(_) => {
+            return Err("BIP-322 signing for P2MR is not yet supported".to_string());
+        }
         WalletScripts::P2trLegacy(script) | WalletScripts::P2trMusig2(script) => {
             // For taproot, sign_path is required
             let (signer_idx, cosigner_idx) =

packages/wasm-utxo/src/fixed_script_wallet/bitgo_psbt/mod.rs

@@ -1014,6 +1014,9 @@ impl BitGoPsbt {
                     create_bip32_derivation(wallet_keys, chain, derivation_index);
                 psbt_input.witness_script = Some(script.witness_script.clone());
             }
+            WalletScripts::P2mr(_) => {
+                return Err("P2MR PSBT input signing is not yet supported".to_string());
+            }
             WalletScripts::P2trLegacy(script) | WalletScripts::P2trMusig2(script) => {
                 let sign_path = options.sign_path.ok_or_else(|| {
                     "sign_path is required for p2tr/p2trMusig2 inputs".to_string()
@@ -1168,6 +1171,20 @@ impl BitGoPsbt {
                     create_bip32_derivation(wallet_keys, chain, derivation_index);
                 psbt_output.witness_script = Some(script.witness_script.clone());
             }
+            WalletScripts::P2mr(_) => {
+                // P2MR uses the same leaf structure as P2TR legacy (3 leaves, no musig2).
+                // We reuse taproot PSBT fields (tap_tree, tap_key_origins) since
+                // all tested PSBT parsers accept them on witness v2 outputs.
+                // No tap_internal_key (P2MR has no internal key or tweak).
+                psbt_output.tap_tree = Some(build_tap_tree_for_output(&pub_triple, false));
+                psbt_output.tap_key_origins = create_tap_bip32_derivation_for_output(
+                    wallet_keys,
+                    chain,
+                    derivation_index,
+                    &pub_triple,
+                    false,
+                );
+            }
             WalletScripts::P2trLegacy(script) | WalletScripts::P2trMusig2(script) => {
                 let is_musig2 = matches!(scripts, WalletScripts::P2trMusig2(_));
 

packages/wasm-utxo/src/fixed_script_wallet/bitgo_psbt/psbt_wallet_input.rs

@@ -751,6 +751,7 @@ pub enum InputScriptType {
     P2trLegacy,
     P2trMusig2ScriptPath,
     P2trMusig2KeyPath,
+    P2mr,
 }
 
 impl InputScriptType {
@@ -769,6 +770,7 @@ impl InputScriptType {
                     Ok(InputScriptType::P2trMusig2KeyPath)
                 }
             }
+            OutputScriptType::P2mr => Ok(InputScriptType::P2mr),
         }
     }
 

packages/wasm-utxo/src/fixed_script_wallet/wallet_scripts/checksigverify.rs

@@ -4,6 +4,9 @@ use crate::bitcoin::blockdata::opcodes::all::{OP_CHECKSIG, OP_CHECKSIGVERIFY};
 use crate::bitcoin::blockdata::script::Builder;
 use crate::bitcoin::{CompressedPublicKey, ScriptBuf};
 use crate::fixed_script_wallet::wallet_keys::PubTriple;
+use crate::p2mr::{
+    build_p2mr_script_pubkey, build_p2mr_tree, ScriptTreeNode, TAPSCRIPT_LEAF_VERSION,
+};
 
 /// Helper to convert CompressedPublicKey to x-only (32 bytes)
 fn to_xonly_pubkey(key: CompressedPublicKey) -> [u8; 32] {
@@ -204,12 +207,304 @@ impl ScriptP2tr {
     }
 }
 
+/// Build the P2MR script tree for a BitGo wallet.
+///
+/// Tree structure (mirrors P2trLegacy, 3 leaves):
+/// - Leaf 0 (depth 1): user + bitgo  (primary spend path)
+/// - Leaf 1 (depth 2): user + backup (recovery)
+/// - Leaf 2 (depth 2): backup + bitgo (recovery)
+///
+/// Each leaf uses the same 2-of-2 checksigverify script as P2TR.
+fn build_p2mr_script_tree(keys: &PubTriple) -> ScriptTreeNode {
+    let [user, backup, bitgo] = *keys;
+
+    let leaf_user_bitgo = ScriptTreeNode::Leaf {
+        script: build_p2tr_ns_script(&[user, bitgo]).into_bytes(),
+        leaf_version: TAPSCRIPT_LEAF_VERSION,
+    };
+    let leaf_user_backup = ScriptTreeNode::Leaf {
+        script: build_p2tr_ns_script(&[user, backup]).into_bytes(),
+        leaf_version: TAPSCRIPT_LEAF_VERSION,
+    };
+    let leaf_backup_bitgo = ScriptTreeNode::Leaf {
+        script: build_p2tr_ns_script(&[backup, bitgo]).into_bytes(),
+        leaf_version: TAPSCRIPT_LEAF_VERSION,
+    };
+
+    // Branch(leaf0, Branch(leaf1, leaf2)) — same depth structure as P2trLegacy
+    ScriptTreeNode::Branch(
+        Box::new(leaf_user_bitgo),
+        Box::new(ScriptTreeNode::Branch(
+            Box::new(leaf_user_backup),
+            Box::new(leaf_backup_bitgo),
+        )),
+    )
+}
+
+/// P2MR wallet script: 3-leaf Merkle tree using 2-of-2 checksigverify leaf scripts.
+///
+/// Unlike P2TR, P2MR has no internal key and no TapTweak.
+/// The Merkle root is committed directly in the scriptPubKey (OP_2 <32-byte root>).
+/// Control blocks are 1 + 32*depth bytes (no 32-byte internal key prefix).
+#[derive(Debug)]
+pub struct ScriptP2mr {
+    /// The 32-byte Merkle root committed in the scriptPubKey.
+    pub merkle_root: [u8; 32],
+    /// Per-leaf spending info (leaf hash + control block), in tree DFS order.
+    pub leaves: Vec<crate::p2mr::P2mrLeafInfo>,
+}
+
+impl ScriptP2mr {
+    /// Build a P2MR wallet script from a public key triple.
+    pub fn new(keys: &PubTriple) -> ScriptP2mr {
+        let tree = build_p2mr_script_tree(keys);
+        let info = build_p2mr_tree(&tree);
+        ScriptP2mr {
+            merkle_root: info.merkle_root,
+            leaves: info.leaves,
+        }
+    }
+
+    /// Return the 34-byte P2MR scriptPubKey: `OP_2 OP_PUSHBYTES_32 <merkle_root>`.
+    pub fn output_script(&self) -> ScriptBuf {
+        build_p2mr_script_pubkey(&self.merkle_root)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::bitcoin::CompressedPublicKey;
     use crate::fixed_script_wallet::test_utils::fixtures::load_fixture_p2tr_output_scripts;
 
+    fn parse_compressed_pubkey(hex: &str) -> CompressedPublicKey {
+        let bytes = hex::decode(hex).expect("Invalid hex pubkey");
+        CompressedPublicKey::from_slice(&bytes).expect("Invalid compressed pubkey")
+    }
+
+    fn pub_triple_from_hex(user: &str, backup: &str, bitgo: &str) -> [CompressedPublicKey; 3] {
+        [
+            parse_compressed_pubkey(user),
+            parse_compressed_pubkey(backup),
+            parse_compressed_pubkey(bitgo),
+        ]
+    }
+
+    /// P2MR output script fixture: known pubkey triple → expected merkle root + output script + control blocks.
+    ///
+    /// Tree structure: Branch(leaf_user_bitgo, Branch(leaf_user_backup, leaf_backup_bitgo))
+    /// - leaf[0]: user+bitgo at depth 1 (primary spend path)
+    /// - leaf[1]: user+backup at depth 2 (recovery)
+    /// - leaf[2]: backup+bitgo at depth 2 (recovery)
+    ///
+    /// Control blocks: 1 byte (0xc1 = TAPSCRIPT_LEAF_VERSION | parity) + 32*depth bytes.
+    struct P2mrFixture {
+        pubkeys: [&'static str; 3],
+        /// Expected 32-byte merkle root (hex).
+        merkle_root: &'static str,
+        /// Expected 34-byte output scriptPubKey (hex): `5220<merkle_root>`.
+        output: &'static str,
+        /// Expected control blocks for leaf[0], leaf[1], leaf[2] in DFS order.
+        control_blocks: [&'static str; 3],
+    }
+
+    fn p2mr_fixtures() -> Vec<P2mrFixture> {
+        vec![
+            // Fixture 0: standard key order (user, backup, bitgo)
+            // Same pubkeys as the first p2tr fixture for cross-comparison
+            P2mrFixture {
+                pubkeys: [
+                    "02d20a62701c54f6eb3abb9f964b0e29ff90ffa3b4e3fcb73e7c67d4950fa6e3c7",
+                    "028714039c6866c27eb6885ffbb4085964a603140e5a39b0fa29b1d9839212f9a2",
+                    "03203ab799ce28e2cca044f594c69275050af4bb0854ad730a8f74622342300e64",
+                ],
+                merkle_root: "b69e64804422cb6cac96df1d742055b41aca27017dfcf79ef68482fad348b5c3",
+                output: "5220b69e64804422cb6cac96df1d742055b41aca27017dfcf79ef68482fad348b5c3",
+                control_blocks: [
+                    // leaf[0] (user+bitgo, depth 1): control_byte || sibling_of_subtree(leaf[1],leaf[2])
+                    "c1d88b89f6f10f490bb6e1e61585cb3e78f8b4993e574b4031cacc6859c5adbc45",
+                    // leaf[1] (user+backup, depth 2): control_byte || sibling_leaf[2] || sibling_subtree(leaf[0])
+                    "c1b33e39fb32e503897e9cdc949597dac7b156017bf55a4f9802b619db07d3070a62959ac7472a3cd0ea894b23888341247d3c890c711fff8ac9b02177609e3e27",
+                    // leaf[2] (backup+bitgo, depth 2): control_byte || sibling_leaf[1] || sibling_subtree(leaf[0])
+                    "c10e87e7b2bddc1e2f2cde702b5cbe51119df98538b35fa91c40a7c74fa9f5d39862959ac7472a3cd0ea894b23888341247d3c890c711fff8ac9b02177609e3e27",
+                ],
+            },
+            // Fixture 1: different key order (user=bitgo key from fixture 0, backup same, bitgo=user key from fixture 0)
+            P2mrFixture {
+                pubkeys: [
+                    "03203ab799ce28e2cca044f594c69275050af4bb0854ad730a8f74622342300e64",
+                    "028714039c6866c27eb6885ffbb4085964a603140e5a39b0fa29b1d9839212f9a2",
+                    "02d20a62701c54f6eb3abb9f964b0e29ff90ffa3b4e3fcb73e7c67d4950fa6e3c7",
+                ],
+                merkle_root: "e4ca158ee6f82dec51f1ecec71665f0735c170bf89c1fe9f9e568ad6257fabc0",
+                output: "5220e4ca158ee6f82dec51f1ecec71665f0735c170bf89c1fe9f9e568ad6257fabc0",
+                control_blocks: [
+                    "c1154989ec963f9639848d336c522641b38bf5540ca0934318ac824e623ffd9e14",
+                    "c19f8d752c1becee80ffd87719934911d9c8aef659fc3ab512ba67f920ffc47545c3a4b27e58190225770a6cf2fb7ee0d9c536951637b3b0cea693d8ba9528853d",
+                    "c145fc694de6d51e7c6fcd37c35377b99e4e6e9a19adb600256a20dc0dd34561bcc3a4b27e58190225770a6cf2fb7ee0d9c536951637b3b0cea693d8ba9528853d",
+                ],
+            },
+            // Fixture 2: secp256k1 generator points (well-known keys)
+            P2mrFixture {
+                pubkeys: [
+                    "0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798",
+                    "02c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5",
+                    "02f9308a019258c31049344f85f89d5229b531c845836f99b08601f113bce036f9",
+                ],
+                merkle_root: "a5d2a17f0e34db3c9d55a4943e6828ce1c931e96d5f46bdf20a1d036fde07d34",
+                output: "5220a5d2a17f0e34db3c9d55a4943e6828ce1c931e96d5f46bdf20a1d036fde07d34",
+                control_blocks: [
+                    "c1508c4c7eb9cae751fa8b8daf40586e3c11f4a8c925538ead255a4df5f28e7fd3",
+                    "c1c9bcb65c1015db6b44e5c2977606cf7a5d8f13d226531c6d01133d0810bed17badc6b97cf6faab3e93e0bb6ca965fd1976982d39a86806d0e9603bfda05f46b4",
+                    "c1df6587a7f3cf367a076047bc0e85893cabb6b1430f9e95ffc0003dad6593ba33adc6b97cf6faab3e93e0bb6ca965fd1976982d39a86806d0e9603bfda05f46b4",
+                ],
+            },
+        ]
+    }
+
+    #[test]
+    fn test_p2mr_output_scripts_fixture() {
+        use crate::p2mr::verify_control_block;
+
+        for (i, fixture) in p2mr_fixtures().iter().enumerate() {
+            let triple =
+                pub_triple_from_hex(fixture.pubkeys[0], fixture.pubkeys[1], fixture.pubkeys[2]);
+            let script = ScriptP2mr::new(&triple);
+
+            // Verify merkle root
+            assert_eq!(
+                hex::encode(script.merkle_root),
+                fixture.merkle_root,
+                "Merkle root mismatch for fixture {}",
+                i
+            );
+
+            // Verify output script: OP_2 OP_PUSHBYTES_32 <merkle_root>
+            assert_eq!(
+                script.output_script().to_hex_string(),
+                fixture.output,
+                "Output script mismatch for fixture {}",
+                i
+            );
+            // Sanity: output starts with 5220 (OP_2 OP_PUSHBYTES_32)
+            assert!(
+                fixture.output.starts_with("5220"),
+                "Output script should start with 5220 (OP_2 OP_PUSHBYTES_32) for fixture {}",
+                i
+            );
+
+            // Verify tree produces exactly 3 leaves
+            assert_eq!(
+                script.leaves.len(),
+                3,
+                "Expected 3 leaves for fixture {}",
+                i
+            );
+
+            // Verify control blocks match expected values
+            for (j, (leaf, expected_cb)) in script
+                .leaves
+                .iter()
+                .zip(fixture.control_blocks.iter())
+                .enumerate()
+            {
+                assert_eq!(
+                    hex::encode(&leaf.control_block),
+                    *expected_cb,
+                    "Control block mismatch for fixture {} leaf {}",
+                    i,
+                    j
+                );
+                // Verify control block is cryptographically valid
+                assert!(
+                    verify_control_block(&leaf.leaf_hash, &leaf.control_block, &script.merkle_root),
+                    "Control block verification failed for fixture {} leaf {}",
+                    i,
+                    j
+                );
+            }
+
+            // Verify depth-1 control block is shorter than depth-2 ones:
+            // depth 1: 1 + 32*1 = 33 bytes; depth 2: 1 + 32*2 = 65 bytes
+            assert_eq!(
+                script.leaves[0].control_block.len(),
+                33,
+                "leaf[0] (depth 1) control block should be 33 bytes"
+            );
+            assert_eq!(
+                script.leaves[1].control_block.len(),
+                65,
+                "leaf[1] (depth 2) control block should be 65 bytes"
+            );
+            assert_eq!(
+                script.leaves[2].control_block.len(),
+                65,
+                "leaf[2] (depth 2) control block should be 65 bytes"
+            );
+        }
+    }
+
+    #[test]
+    fn test_p2mr_chain_values() {
+        use crate::fixed_script_wallet::wallet_scripts::{Chain, OutputScriptType, Scope};
+        use std::convert::TryFrom;
+
+        // Chain 360: external P2MR
+        let chain360 = Chain::try_from(360u32).unwrap();
+        assert_eq!(chain360.script_type, OutputScriptType::P2mr);
+        assert_eq!(chain360.scope, Scope::External);
+        assert_eq!(chain360.value(), 360);
+
+        // Chain 361: internal P2MR
+        let chain361 = Chain::try_from(361u32).unwrap();
+        assert_eq!(chain361.script_type, OutputScriptType::P2mr);
+        assert_eq!(chain361.scope, Scope::Internal);
+        assert_eq!(chain361.value(), 361);
+
+        // Round-trip: value() matches what we set
+        assert_eq!(
+            Chain::new(OutputScriptType::P2mr, Scope::External).value(),
+            360
+        );
+        assert_eq!(
+            Chain::new(OutputScriptType::P2mr, Scope::Internal).value(),
+            361
+        );
+    }
+
+    #[test]
+    fn test_p2mr_no_internal_key() {
+        // P2MR output starts with 0x52 (OP_2), not 0x51 (OP_1 / taproot).
+        // This verifies P2MR is distinguishable from P2TR at the scriptPubKey level.
+        let triple = pub_triple_from_hex(
+            "02d20a62701c54f6eb3abb9f964b0e29ff90ffa3b4e3fcb73e7c67d4950fa6e3c7",
+            "028714039c6866c27eb6885ffbb4085964a603140e5a39b0fa29b1d9839212f9a2",
+            "03203ab799ce28e2cca044f594c69275050af4bb0854ad730a8f74622342300e64",
+        );
+        let script = ScriptP2mr::new(&triple);
+        let spk_bytes = script.output_script().to_bytes();
+        assert_eq!(
+            spk_bytes[0], 0x52,
+            "P2MR scriptPubKey must start with OP_2 (0x52)"
+        );
+        assert_eq!(spk_bytes.len(), 34, "P2MR scriptPubKey must be 34 bytes");
+
+        // Compare: P2TR for same keys would start with 0x51
+        let p2tr = ScriptP2tr::new(&triple, false);
+        assert_eq!(
+            p2tr.output_script().to_bytes()[0],
+            0x51,
+            "P2TR scriptPubKey must start with OP_1 (0x51)"
+        );
+
+        // P2MR and P2TR produce different output scripts
+        assert_ne!(
+            script.output_script().to_hex_string(),
+            p2tr.output_script().to_hex_string(),
+            "P2MR and P2TR must produce different output scripts"
+        );
+    }
+
     fn test_p2tr_output_scripts_helper(script_type: &str, use_musig2: bool) {
         let fixtures = load_fixture_p2tr_output_scripts(script_type)
             .unwrap_or_else(|_| panic!("Failed to load {} output script fixtures", script_type));