ENH: Allow RMS wellbores to share SMDA targets

Author: GibranAlfa

src/fmu/settings/models/mappings.py

@@ -307,13 +307,22 @@ def _validate_identifier_mappings_collection(
       of a same-system primary. It is also invalid to add two ``rms -> smda``
       mappings for the same ``source_id``.
 
-    - A cross-system ``target_id`` can be used only once per target system.
+    - A cross-system ``target_id`` can be used only once per target system, except
+      for RMS to SMDA wellbore mappings. Different RMS wellbore names can map to
+      the same SMDA wellbore.
       Example valid mappings::
 
           rms -> rms, primary, source_id="TopVolantis", target_id="TopVolantis"
           rms -> rms, alias, source_id="TOP_VOLANTIS", target_id="TopVolantis"
           rms -> smda, primary, source_id="TopVolantis", target_id="VOLANTIS GP. Top"
 
+      Example valid RMS to SMDA wellbore mappings::
+
+          rms -> rms, primary, source_id="RFT_30_9-B-21_C", target_id="RFT_30_9-B-21_C"
+          rms -> rms, primary, source_id="MLW_30_9-B-21_C", target_id="MLW_30_9-B-21_C"
+          rms -> smda, primary, source_id="RFT_30_9-B-21_C", target_id="NO 30/9-B-21 C"
+          rms -> smda, primary, source_id="MLW_30_9-B-21_C", target_id="NO 30/9-B-21 C"
+
       Example invalid mappings::
 
           rms -> rms, primary, source_id="TopVolantis", target_id="TopVolantis"
@@ -322,7 +331,9 @@ def _validate_identifier_mappings_collection(
           rms -> smda, primary, source_id="Volon", target_id="VOLANTIS GP. Top"
 
     The second cross-system mapping is invalid because one cross-system
-    ``target_id`` cannot be mapped to more than one same-system primary.
+    ``target_id`` cannot be mapped to more than one same-system primary. The
+    exception permits this relationship only for ``wellbore`` mappings from
+    ``rms`` to ``smda``.
     """
     same_system_source_keys: set[tuple[DataSystem, MappingType, str]] = set()
     same_system_primary_source_keys: set[tuple[DataSystem, MappingType, str]] = set()
@@ -368,8 +379,14 @@ def _validate_identifier_mappings_collection(
             )
         cross_system_source_keys.add(cross_system_source_key)
 
-        # A cross-system target_id can only belong to one same-system primary.
-        if mapping.target_id is not None:
+        # RMS wellbore names can share an SMDA wellbore target. Other
+        # cross-system target_ids can only belong to one same-system primary.
+        allows_reused_target_id = (
+            mapping.mapping_type == MappingType.wellbore
+            and mapping.source_system == DataSystem.rms
+            and mapping.target_system == DataSystem.smda
+        )
+        if mapping.target_id is not None and not allows_reused_target_id:
             cross_system_target_key = (
                 mapping.mapping_type,
                 mapping.source_system,

tests/test_mappings_model.py

@@ -535,6 +535,44 @@ def test_validate_collection_rejects_reused_cross_system_target_id() -> None:
         )
 
 
+def test_wellbore_mappings_allow_reused_rms_to_smda_target_id() -> None:
+    """Different RMS wellbore names can map to the same SMDA wellbore."""
+    rft_primary = create_wellbore_mapping(
+        source_system=DataSystem.rms,
+        target_system=DataSystem.rms,
+        source_id="RFT_30_9-B-21_C",
+        target_id="RFT_30_9-B-21_C",
+    )
+    mlw_primary = create_wellbore_mapping(
+        source_system=DataSystem.rms,
+        target_system=DataSystem.rms,
+        source_id="MLW_30_9-B-21_C",
+        target_id="MLW_30_9-B-21_C",
+    )
+    rft_mapping = create_wellbore_mapping(
+        source_system=DataSystem.rms,
+        target_system=DataSystem.smda,
+        source_id="RFT_30_9-B-21_C",
+        target_id="NO 30/9-B-21 C",
+    )
+    mlw_mapping = create_wellbore_mapping(
+        source_system=DataSystem.rms,
+        target_system=DataSystem.smda,
+        source_id="MLW_30_9-B-21_C",
+        target_id="NO 30/9-B-21 C",
+    )
+
+    mappings = InternalWellboreMappings(
+        root=[rft_primary, mlw_primary, rft_mapping, mlw_mapping]
+    )
+
+    converted = mappings.to_wellbore_mappings()
+    assert [(mapping.source_id, mapping.target_id) for mapping in converted] == [
+        ("RFT_30_9-B-21_C", "NO 30/9-B-21 C"),
+        ("MLW_30_9-B-21_C", "NO 30/9-B-21 C"),
+    ]
+
+
 def test_validate_collection_rejects_reused_same_system_source_id() -> None:
     """A source_id cannot be both a primary and an alias in the same collection."""
     primary = create_stratigraphy_mapping()