feat: further MultisigAccount alignment with ts variant (#258)

Align Python implementation with TypeScript PR #492 by adding:
- Implement from_signature() static method to create MultisigAccount from MultisigSignature
- Add create_multisig_transaction() to create empty multisig transaction structure
- Add create_multisig_signature() to create empty multisig signature structure
- Add apply_signature_to_txn() to apply signatures to signed transactions (immutable)
- Remove empty sub_signers validation to support address-only MultisigAccounts

These changes enable better multisig workflow support, particularly for
delegated logic signatures and signature collection scenarios.

Related to algorandfoundation/algokit-utils-ts#492

Author: aorumbayev

src/algokit_transact/multisig.py

@@ -46,13 +46,26 @@ class MultisigAccount:
     sub_signers: Sequence[AddressWithSigners]
     """The list of signing accounts."""
 
-    def __post_init__(self) -> None:
-        if not self.sub_signers:
-            raise ValueError("sub_signers cannot be empty")
-
     @staticmethod
     def from_signature(msig: MultisigSignature) -> "MultisigAccount":
-        raise NotImplementedError
+        """
+        Create a MultisigAccount from a MultisigSignature.
+
+        This is primarily used to extract the multisig address from a signature,
+        such as when dealing with delegated logic signatures.
+
+        Args:
+            msig: The multisig signature to create the account from
+
+        Returns:
+            A MultisigAccount with no sub-signers
+        """
+        params = MultisigMetadata(
+            version=msig.version,
+            threshold=msig.threshold,
+            addrs=[address_from_public_key(subsig.public_key) for subsig in msig.subsigs],
+        )
+        return MultisigAccount(params=params, sub_signers=[])
 
     @cached_property
     def _multisig_signature(self) -> MultisigSignature:
@@ -139,3 +152,69 @@ def apply_signature(self, msig: MultisigSignature, address: str, sig: bytes) ->
                 f"Multisig signature parameters do not match expected multisig parameters. {expected=!r}, {given=!r}"
             )
         return apply_multisig_subsignature(msig, address, sig)
+
+    def create_multisig_transaction(self, txn: AlgokitTransaction) -> SignedTransaction:
+        """
+        Create a multisig transaction without any signatures.
+
+        Args:
+            txn: The transaction to create a multisig transaction for
+
+        Returns:
+            A SignedTransaction with empty multisig structure
+        """
+        msig = self.create_multisig_signature()
+
+        auth_address = self.address if txn.sender != self.address else None
+
+        return SignedTransaction(
+            txn=txn,
+            sig=None,
+            msig=msig,
+            lsig=None,
+            auth_address=auth_address,
+        )
+
+    def create_multisig_signature(self) -> MultisigSignature:
+        """
+        Create an empty multisig signature structure.
+
+        Returns:
+            A MultisigSignature with empty signatures
+        """
+        return new_multisig_signature(
+            self.params.version,
+            self.params.threshold,
+            self.params.addrs,
+        )
+
+    def apply_signature_to_txn(self, txn: SignedTransaction, pubkey: bytes, signature: bytes) -> SignedTransaction:
+        """
+        Apply a signature to a signed transaction, returning a new SignedTransaction.
+
+        Note: Unlike TypeScript which mutates in place, this returns a new SignedTransaction
+        since Python's SignedTransaction is a frozen dataclass.
+
+        Args:
+            txn: The signed transaction to apply the signature to
+            pubkey: The public key of the signer
+            signature: The signature to apply
+
+        Returns:
+            A new SignedTransaction with the signature applied
+        """
+        from dataclasses import replace
+
+        msig = txn.msig
+        if not msig:
+            created_txn = self.create_multisig_transaction(txn.txn)
+            msig = created_txn.msig
+
+        if not msig:
+            raise ValueError("Failed to create multisig signature")
+
+        # Convert to address for validation via apply_signature
+        address = address_from_public_key(pubkey)
+        updated_msig = self.apply_signature(msig, address, signature)
+
+        return replace(txn, msig=updated_msig)

tests/modules/kmd_client/test_delete_v1_key.py

@@ -23,9 +23,7 @@ def test_basic_request_and_response_validation(
     address = generate_test_key(localnet_kmd_client, wallet_handle_token)
 
     # Verify key exists
-    list_before = localnet_kmd_client.list_keys_in_wallet(
-        ListKeysRequest(wallet_handle_token=wallet_handle_token)
-    )
+    list_before = localnet_kmd_client.list_keys_in_wallet(ListKeysRequest(wallet_handle_token=wallet_handle_token))
     assert address in (list_before.addresses or [])
 
     # Delete the key (returns empty response)
@@ -38,7 +36,5 @@ def test_basic_request_and_response_validation(
     )
 
     # Verify key was deleted
-    list_after = localnet_kmd_client.list_keys_in_wallet(
-        ListKeysRequest(wallet_handle_token=wallet_handle_token)
-    )
+    list_after = localnet_kmd_client.list_keys_in_wallet(ListKeysRequest(wallet_handle_token=wallet_handle_token))
     assert address not in (list_after.addresses or [])

tests/modules/kmd_client/test_delete_v1_multisig.py

@@ -23,9 +23,7 @@ def test_basic_request_and_response_validation(
     multisig_address, _, _, _ = create_test_multisig(localnet_kmd_client, wallet_handle_token)
 
     # Verify multisig exists
-    list_before = localnet_kmd_client.list_multisig(
-        ListMultisigRequest(wallet_handle_token=wallet_handle_token)
-    )
+    list_before = localnet_kmd_client.list_multisig(ListMultisigRequest(wallet_handle_token=wallet_handle_token))
     assert multisig_address in (list_before.addresses or [])
 
     # Delete the multisig (returns empty response)
@@ -38,7 +36,5 @@ def test_basic_request_and_response_validation(
     )
 
     # Verify multisig was deleted
-    list_after = localnet_kmd_client.list_multisig(
-        ListMultisigRequest(wallet_handle_token=wallet_handle_token)
-    )
+    list_after = localnet_kmd_client.list_multisig(ListMultisigRequest(wallet_handle_token=wallet_handle_token))
     assert multisig_address not in (list_after.addresses or [])

tests/modules/kmd_client/test_post_v1_key.py

@@ -17,15 +17,11 @@ def test_basic_request_and_response_validation(
     """Given a known request validate that the same request can be made using our models. Then, validate that our response model aligns with the known response"""
     wallet_handle_token, _, _ = wallet_handle
 
-    result = localnet_kmd_client.generate_key(
-        GenerateKeyRequest(wallet_handle_token=wallet_handle_token)
-    )
+    result = localnet_kmd_client.generate_key(GenerateKeyRequest(wallet_handle_token=wallet_handle_token))
 
     assert result.address is not None
 
     # Verify the key exists in the wallet
-    list_result = localnet_kmd_client.list_keys_in_wallet(
-        ListKeysRequest(wallet_handle_token=wallet_handle_token)
-    )
+    list_result = localnet_kmd_client.list_keys_in_wallet(ListKeysRequest(wallet_handle_token=wallet_handle_token))
     addresses = list_result.addresses or []
     assert result.address in addresses

tests/modules/kmd_client/test_post_v1_key_list.py

@@ -22,9 +22,7 @@ def test_basic_request_and_response_validation(
     # Generate at least one key
     generate_test_key(localnet_kmd_client, wallet_handle_token)
 
-    result = localnet_kmd_client.list_keys_in_wallet(
-        ListKeysRequest(wallet_handle_token=wallet_handle_token)
-    )
+    result = localnet_kmd_client.list_keys_in_wallet(ListKeysRequest(wallet_handle_token=wallet_handle_token))
 
     assert result.addresses is not None
     assert len(result.addresses) > 0

tests/modules/kmd_client/test_post_v1_multisig_list.py

@@ -22,9 +22,7 @@ def test_basic_request_and_response_validation(
     # Create a multisig first
     multisig_address, _, _, _ = create_test_multisig(localnet_kmd_client, wallet_handle_token)
 
-    result = localnet_kmd_client.list_multisig(
-        ListMultisigRequest(wallet_handle_token=wallet_handle_token)
-    )
+    result = localnet_kmd_client.list_multisig(ListMultisigRequest(wallet_handle_token=wallet_handle_token))
 
     assert result.addresses is not None
     # Verify the multisig is in the list

tests/modules/kmd_client/test_post_v1_wallet_info.py

@@ -17,8 +17,6 @@ def test_basic_request_and_response_validation(
     """Given a known request validate that the same request can be made using our models. Then, validate that our response model aligns with the known response"""
     wallet_handle_token, _, _ = wallet_handle
 
-    result = localnet_kmd_client.wallet_info(
-        WalletInfoRequest(wallet_handle_token=wallet_handle_token)
-    )
+    result = localnet_kmd_client.wallet_info(WalletInfoRequest(wallet_handle_token=wallet_handle_token))
 
     assert result.wallet_handle is not None

tests/modules/kmd_client/test_post_v1_wallet_rename.py

@@ -31,9 +31,7 @@ def test_basic_request_and_response_validation(
     assert result.wallet is not None
 
     # Verify the wallet was renamed
-    wallet_info = localnet_kmd_client.wallet_info(
-        WalletInfoRequest(wallet_handle_token=wallet_handle_token)
-    )
+    wallet_info = localnet_kmd_client.wallet_info(WalletInfoRequest(wallet_handle_token=wallet_handle_token))
     assert wallet_info.wallet_handle is not None
     assert wallet_info.wallet_handle.wallet is not None
     assert wallet_info.wallet_handle.wallet.name == new_wallet_name