Added implementation for custom derivation park

src/seedsigner/helpers/embit_utils.py

@@ -136,7 +136,12 @@ def parse_derivation_path(derivation_path: str) -> dict:
 
     sections = derivation_path.split("/")
 
-    if sections[1] == "48h":
+    # Paths shorter than m/purpose/network/... are invalid for standard matching,
+    # but we still parse leniently so callers can handle the result gracefully.
+    purpose = sections[1] if len(sections) > 1 else None
+    network = sections[2] if len(sections) > 2 else None
+
+    if purpose == "48h":
         # So far this helper is only meant for single sig message signing
         raise Exception("Not implemented")
 
@@ -154,20 +159,23 @@ def parse_derivation_path(derivation_path: str) -> dict:
     }
 
     details = dict()
-    details["script_type"] = lookups["script_types"].get(sections[1])
+    details["script_type"] = lookups["script_types"].get(purpose)
     if not details["script_type"]:
         details["script_type"] = SettingsConstants.CUSTOM_DERIVATION
-    details["network"] = lookups["networks"].get(sections[2])
+    details["network"] = lookups["networks"].get(network)
+
+    change = sections[-2] if len(sections) > 1 else None
+    index = sections[-1] if len(sections) > 0 else None
 
     # Check if there's a standard change path
-    if sections[-2] in ["0", "1"]:
-        details["is_change"] = sections[-2] == "1"
+    if change in ["0", "1"]:
+        details["is_change"] = change == "1"
     else:
         details["is_change"] = None
 
     # Check if there's a standard address index
-    if sections[-1].isdigit():
-        details["index"] = int(sections[-1])
+    if index and index.isdigit():
+        details["index"] = int(index)
     else:
         details["index"] = None
 

src/seedsigner/views/tools_views.py

@@ -571,21 +571,31 @@ def __init__(self, seed_num: int = None, script_type: str = None, custom_derivat
             self.seed = self.controller.storage.seeds[seed_num]
             data["seed_num"] = self.seed
             seed_derivation_override = self.seed.derivation_override(sig_type=SettingsConstants.SINGLE_SIG)
-
+            custom_derivation_details = None
+            from seedsigner.helpers import embit_utils
             if self.script_type == SettingsConstants.CUSTOM_DERIVATION:
                 derivation_path = self.custom_derivation
+                custom_derivation_details = embit_utils.parse_derivation_path(derivation_path)
             elif seed_derivation_override:
                 derivation_path = seed_derivation_override
             else:
-                from seedsigner.helpers import embit_utils
                 derivation_path = embit_utils.get_standard_derivation_path(
                     network=self.settings.get_value(SettingsConstants.SETTING__NETWORK),
                     wallet_type=SettingsConstants.SINGLE_SIG,
                     script_type=self.script_type,
                 )
 
+            xpub_derivation_path = derivation_path
+            if custom_derivation_details and custom_derivation_details["wallet_derivation_path"]:
+                # If the user entered a full path that includes /change/index, derive
+                # from the wallet-level path so we can still enumerate addresses.
+                # The receive/change branch is selected later via the UI toggle.
+                xpub_derivation_path = custom_derivation_details["wallet_derivation_path"]
+
             data["derivation_path"] = derivation_path
-            data["xpub"] = self.seed.get_xpub(derivation_path, network=network)
+            if custom_derivation_details:
+                data["custom_derivation_details"] = custom_derivation_details
+            data["xpub"] = self.seed.get_xpub(xpub_derivation_path, network=network)
 
         else:
             data["wallet_descriptor"] = self.controller.multisig_wallet_descriptor
@@ -675,14 +685,27 @@ def run(self):
                 if "xpub" in data:
                     # Single sig explore from seed
                     if "script_type" in data and data["script_type"] != SettingsConstants.CUSTOM_DERIVATION:
-                        # Standard derivation path
-                        for i in range(self.start_index, self.start_index + addrs_per_screen):
-                            address = embit_utils.get_single_sig_address(xpub=data["xpub"], script_type=data["script_type"], index=i, is_change=self.is_change, embit_network=data["embit_network"])
-                            addresses.append(address)
-                            data[addr_storage_key].append(address)
+                        script_type = data["script_type"]
+                        index_offset = 0
+
                     else:
-                        # TODO: Custom derivation path
-                        raise Exception(_("Custom Derivation address explorer not yet implemented"))
+                        custom_derivation_details = data.get("custom_derivation_details")
+                        if not custom_derivation_details:
+                            raise Exception(_("Routing error: missing custom derivation details"))
+
+                        script_type = custom_derivation_details["script_type"]
+                        if script_type == SettingsConstants.CUSTOM_DERIVATION:
+                            raise Exception(_("Address Explorer does not support non-standard custom script paths"))
+
+                        # Keep the user-entered index as the pagination start offset.
+                        # Intentionally ignore parsed `is_change`: branch selection comes
+                        # from the current Receive/Change screen selection (`self.is_change`).
+                        index_offset = custom_derivation_details["index"] if custom_derivation_details["index"] is not None else 0
+
+                    for i in range(self.start_index + index_offset, self.start_index + index_offset + addrs_per_screen):
+                        address = embit_utils.get_single_sig_address(xpub=data["xpub"], script_type=script_type, index=i, is_change=self.is_change, embit_network=data["embit_network"])
+                        addresses.append(address)
+                        data[addr_storage_key].append(address)
 
                 elif "wallet_descriptor" in data:
                     from embit.descriptor import Descriptor

tests/test_embit_utils.py

@@ -455,3 +455,10 @@ def test_parse_derivation_path():
             assert actual_result["index"] == expected_result[3]
         else:
             assert actual_result["index"] == int(derivation_path.split("/")[-1])
+
+
+def test_parse_derivation_path_short_custom_paths_do_not_crash():
+    for derivation_path in ["m", "m/9h", "m/9h/78"]:
+        parsed = embit_utils.parse_derivation_path(derivation_path)
+        assert parsed["script_type"] == SC.CUSTOM_DERIVATION
+        assert parsed["clean_match"] is False

tests/test_flows_tools.py

@@ -34,6 +34,40 @@ def test__address_explorer__flow(self):
         ])
 
 
+    def test__address_explorer__custom_derivation_flow(self):
+        """
+            Address Explorer should support custom derivation paths that still map to a
+            known single sig script type.
+        """
+        controller = Controller.get_instance()
+        seed = Seed(mnemonic=["abandon "* 11 + "about"])
+        controller.storage.set_pending_seed(seed)
+        controller.storage.finalize_pending_seed()
+
+        self.settings.set_value(
+            SettingsConstants.SETTING__SCRIPT_TYPES,
+            [SettingsConstants.NATIVE_SEGWIT, SettingsConstants.CUSTOM_DERIVATION],
+        )
+
+        custom_derivation_selection = ButtonOption(
+            SettingsDefinition.get_settings_entry(SettingsConstants.SETTING__SCRIPT_TYPES).get_selection_option_display_name_by_value(SettingsConstants.CUSTOM_DERIVATION),
+            return_data=SettingsConstants.CUSTOM_DERIVATION,
+        )
+
+        self.run_sequence([
+            FlowStep(MainMenuView, button_data_selection=MainMenuView.TOOLS),
+            FlowStep(tools_views.ToolsMenuView, button_data_selection=tools_views.ToolsMenuView.ADDRESS_EXPLORER),
+            FlowStep(tools_views.ToolsAddressExplorerSelectSourceView, screen_return_value=0),  # ret 1st onboard seed
+            FlowStep(seed_views.SeedExportXpubScriptTypeView, button_data_selection=custom_derivation_selection),
+            FlowStep(seed_views.SeedExportXpubCustomDerivationView, screen_return_value="m/44'/1237'/0'/0/0"),
+            FlowStep(tools_views.ToolsAddressExplorerAddressTypeView, button_data_selection=tools_views.ToolsAddressExplorerAddressTypeView.RECEIVE),
+            FlowStep(tools_views.ToolsAddressExplorerAddressListView, screen_return_value=10),  # ret NEXT page of addrs
+            FlowStep(tools_views.ToolsAddressExplorerAddressListView, screen_return_value=4),  # ret a specific addr from the list
+            FlowStep(tools_views.ToolsAddressExplorerAddressView),  # runs until dismissed; no ret value
+            FlowStep(tools_views.ToolsAddressExplorerAddressListView),
+        ])
+
+
     def test__address_explorer__loadseed__sideflow(self):
         """
             Finalizing a seed during the Address Explorer flow should return to the next