refactor: stop reading joinColumnName from relation field settings (#20304)

## Summary

`joinColumnName` on relation field settings is always derivable from the
field name (and the target object name for morph relations). This PR
stops reading it from settings anywhere in production code; the stored
value is no longer used.

The settings field is **not** removed from data yet — a follow-up can
drop it once we are confident nothing depends on the stored value.

## Helpers

The helpers are split by layer because frontend and backend hold morph
relations differently: the frontend has a base name plus a
`morphRelations[]` array, the backend has one row per target with the
name already morph-resolved.

| Helper | Layer | When to use |
|---|---|---|
| `computeRelationGqlFieldJoinColumnName` | Shared / frontend
(`gqlField`) | Non-morph relation on the frontend. |
| `computeMorphRelationGqlFieldName` | Shared / frontend (`gqlField`) |
Need the per-target morph gqlField name (e.g. `targetCompany`). |
| `computeMorphRelationGqlFieldJoinColumnName` | Shared / frontend
(`gqlField`) | Per-target morph join column on the frontend. Prefer over
the non-morph helper for any morph field — it forces the per-target
inputs. |
| `computeMorphOrRelationFieldJoinColumnName` | Backend
(`FlatFieldMetadata.name`) | Any backend read or write — the flat name
is already morph-resolved, so one helper covers both cases. |
| `computeMorphRelationFlatFieldName` | Backend
(`FlatFieldMetadata.name`) | **Mutation paths only** (create / update /
object rename). Reads consume the stored `field.name` and never call
this. |

## Test plan

- [x] Typecheck and lint (front, server, shared)
- [x] Existing unit tests pass
- [ ] CI green

packages/twenty-front/src/modules/object-record/cache/utils/computePossibleMorphGqlFieldForFieldName.ts

@@ -1,5 +1,5 @@
 import { type FieldMorphRelationMetadata } from '@/object-record/record-field/ui/types/FieldMetadata';
-import { computeMorphRelationFieldName } from 'twenty-shared/utils';
+import { computeMorphRelationGqlFieldName } from 'twenty-shared/utils';
 export const computePossibleMorphGqlFieldForFieldName = ({
   fieldMetadata,
 }: {
@@ -9,7 +9,7 @@ export const computePossibleMorphGqlFieldForFieldName = ({
   >;
 }) =>
   fieldMetadata.morphRelations.map((morphRelation) => {
-    return computeMorphRelationFieldName({
+    return computeMorphRelationGqlFieldName({
       fieldName: fieldMetadata.fieldName,
       relationType: morphRelation.type,
       targetObjectMetadataNameSingular:

packages/twenty-front/src/modules/object-record/cache/utils/getFieldMetadataFromGqlField.ts

@@ -1,6 +1,7 @@
 import { type EnrichedObjectMetadataItem } from '@/object-metadata/types/EnrichedObjectMetadataItem';
 import { computePossibleMorphGqlFieldForFieldName } from '@/object-record/cache/utils/computePossibleMorphGqlFieldForFieldName';
 import { isFieldMorphRelation } from '@/object-record/record-field/ui/types/guards/isFieldMorphRelation';
+import { computeRelationGqlFieldJoinColumnName } from 'twenty-shared/utils';
 
 export const getFieldMetadataFromGqlField = ({
   objectMetadataItem,
@@ -12,7 +13,9 @@ export const getFieldMetadataFromGqlField = ({
   return (
     objectMetadataItem.fields.find((field) => field.name === gqlField) ??
     objectMetadataItem.fields.find(
-      (field) => field.settings?.joinColumnName === gqlField,
+      (field) =>
+        computeRelationGqlFieldJoinColumnName({ name: field.name }) ===
+        gqlField,
     ) ??
     objectMetadataItem.fields.filter(isFieldMorphRelation).find((field) => {
       const morphRelations = field.morphRelations;
@@ -27,7 +30,9 @@ export const getFieldMetadataFromGqlField = ({
       return possibleMorphRelationsNames
         .flatMap((possibleMorphRelationName) => [
           possibleMorphRelationName,
-          `${possibleMorphRelationName}Id`,
+          computeRelationGqlFieldJoinColumnName({
+            name: possibleMorphRelationName,
+          }),
         ])
         .includes(gqlField);
     })

packages/twenty-front/src/modules/object-record/cache/utils/getMorphRelationFromFieldMetadataAndGqlField.ts

@@ -1,7 +1,7 @@
 import { type EnrichedObjectMetadataItem } from '@/object-metadata/types/EnrichedObjectMetadataItem';
 
 import { type FieldMorphRelationMetadata } from '@/object-record/record-field/ui/types/FieldMetadata';
-import { computeMorphRelationFieldName } from 'twenty-shared/utils';
+import { computeMorphRelationGqlFieldName } from 'twenty-shared/utils';
 
 export const getMorphRelationFromFieldMetadataAndGqlField = ({
   objectMetadataItems,
@@ -24,7 +24,7 @@ export const getMorphRelationFromFieldMetadataAndGqlField = ({
           morphRelation: undefined,
         };
       }
-      const computedName = computeMorphRelationFieldName({
+      const computedName = computeMorphRelationGqlFieldName({
         fieldName: morphRelation.sourceFieldMetadata.name,
         relationType: morphRelation.type,
         targetObjectMetadataNameSingular: targetObjectMetadata.nameSingular,

packages/twenty-front/src/modules/object-record/cache/utils/getRecordNodeFromRecord.ts

@@ -9,7 +9,12 @@ import { getRecordConnectionFromRecords } from '@/object-record/cache/utils/getR
 import { getRefName } from '@/object-record/cache/utils/getRefName';
 import { type RecordGqlNode } from '@/object-record/graphql/types/RecordGqlNode';
 import { type ObjectRecord } from '@/object-record/types/ObjectRecord';
-import { getNodeTypename, isDefined, pascalCase } from 'twenty-shared/utils';
+import {
+  computeRelationGqlFieldJoinColumnName,
+  getNodeTypename,
+  isDefined,
+  pascalCase,
+} from 'twenty-shared/utils';
 import { FieldMetadataType, RelationType } from '~/generated-metadata/graphql';
 
 export const getRecordNodeFromRecord = <T extends ObjectRecord>({
@@ -132,7 +137,9 @@ export const getRecordNodeFromRecord = <T extends ObjectRecord>({
 
         switch (field.type) {
           case FieldMetadataType.RELATION: {
-            const isJoinColumn = field.settings?.joinColumnName === gqlField;
+            const isJoinColumn =
+              computeRelationGqlFieldJoinColumnName({ name: field.name }) ===
+              gqlField;
             if (isJoinColumn) {
               return [gqlField, value];
             }