diff --git a/package-lock.json b/package-lock.json
index c3f71980565..946aa7d9f8a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -43237,6 +43237,7 @@
       "version": "3.23.8",
       "resolved": "https://registry.npmjs.org/zod/-/zod-3.23.8.tgz",
       "integrity": "sha512-XBx9AXhXktjUqnepgTiE5flcKIYWi/rme0Eaj+5Y0lftuGBq+jyRu/md4WnuxqgP1ubdpNCsYEYPxrzVHD8d6g==",
+      "dev": true,
       "license": "MIT",
       "funding": {
         "url": "https://github.com/sponsors/colinhacks"
@@ -46108,8 +46109,7 @@
         "js-yaml": "^4.1.0",
         "lodash": "^4.17.21",
         "react": "^17.0.2",
-        "yargs-parser": "^21.1.1",
-        "zod": "^3.22.3"
+        "yargs-parser": "^21.1.1"
       },
       "devDependencies": {
         "@mongodb-js/eslint-config-compass": "^1.3.8",
@@ -47005,7 +47005,7 @@
         "@mongodb-js/compass-logging": "^1.6.9",
         "@mongodb-js/compass-utils": "^0.8.8",
         "write-file-atomic": "^5.0.1",
-        "zod": "^3.22.3"
+        "zod": "^3.25.17"
       },
       "devDependencies": {
         "@mongodb-js/eslint-config-compass": "^1.3.8",
@@ -47075,6 +47075,15 @@
         "node": "^14.17.0 || ^16.13.0 || >=18.0.0"
       }
     },
+    "packages/compass-user-data/node_modules/zod": {
+      "version": "3.25.17",
+      "resolved": "https://registry.npmjs.org/zod/-/zod-3.25.17.tgz",
+      "integrity": "sha512-8hQzQ/kMOIFbwOgPrm9Sf9rtFHpFUMy4HvN0yEB0spw14aYi0uT5xG5CE2DB9cd51GWNsz+DNO7se1kztHMKnw==",
+      "license": "MIT",
+      "funding": {
+        "url": "https://github.com/sponsors/colinhacks"
+      }
+    },
     "packages/compass-utils": {
       "name": "@mongodb-js/compass-utils",
       "version": "0.8.8",
@@ -58856,7 +58865,7 @@
         "sinon": "^9.2.3",
         "typescript": "^5.0.4",
         "write-file-atomic": "^5.0.1",
-        "zod": "^3.22.3"
+        "zod": "^3.25.17"
       },
       "dependencies": {
         "diff": {
@@ -58892,6 +58901,11 @@
             "imurmurhash": "^0.1.4",
             "signal-exit": "^4.0.1"
           }
+        },
+        "zod": {
+          "version": "3.25.17",
+          "resolved": "https://registry.npmjs.org/zod/-/zod-3.25.17.tgz",
+          "integrity": "sha512-8hQzQ/kMOIFbwOgPrm9Sf9rtFHpFUMy4HvN0yEB0spw14aYi0uT5xG5CE2DB9cd51GWNsz+DNO7se1kztHMKnw=="
         }
       }
     },
@@ -68442,8 +68456,7 @@
         "mocha": "^10.2.0",
         "react": "^17.0.2",
         "sinon": "^9.2.3",
-        "yargs-parser": "^21.1.1",
-        "zod": "^3.22.3"
+        "yargs-parser": "^21.1.1"
       },
       "dependencies": {
         "sinon": {
@@ -89129,7 +89142,8 @@
     "zod": {
       "version": "3.23.8",
       "resolved": "https://registry.npmjs.org/zod/-/zod-3.23.8.tgz",
-      "integrity": "sha512-XBx9AXhXktjUqnepgTiE5flcKIYWi/rme0Eaj+5Y0lftuGBq+jyRu/md4WnuxqgP1ubdpNCsYEYPxrzVHD8d6g=="
+      "integrity": "sha512-XBx9AXhXktjUqnepgTiE5flcKIYWi/rme0Eaj+5Y0lftuGBq+jyRu/md4WnuxqgP1ubdpNCsYEYPxrzVHD8d6g==",
+      "dev": true
     }
   }
 }
diff --git a/packages/compass-data-modeling/src/components/diagram-editor.tsx b/packages/compass-data-modeling/src/components/diagram-editor.tsx
index a0a60db4a59..4bbe255df49 100644
--- a/packages/compass-data-modeling/src/components/diagram-editor.tsx
+++ b/packages/compass-data-modeling/src/components/diagram-editor.tsx
@@ -19,8 +19,11 @@ import {
   spacing,
   Button,
   palette,
+  ErrorSummary,
 } from '@mongodb-js/compass-components';
 import { cancelAnalysis, retryAnalysis } from '../store/analysis-process';
+import type { Edit, StaticModel } from '../services/data-model-storage';
+import { UUID } from 'bson';
 
 const loadingContainerStyles = css({
   width: '100%',
@@ -73,17 +76,29 @@ const modelPreviewStyles = css({
 });
 
 const editorContainerStyles = css({
-  height: 160 + 34 + 16,
   display: 'flex',
   flexDirection: 'column',
   gap: 8,
   boxShadow: `0 0 0 2px ${palette.gray.light2}`,
 });
 
-const editorContainerApplyButtonStyles = css({
+const editorContainerApplyContainerStyles = css({
   paddingLeft: 8,
   paddingRight: 8,
-  alignSelf: 'flex-end',
+  justifyContent: 'flex-end',
+  gap: spacing[200],
+  display: 'flex',
+  width: '100%',
+  height: spacing[100],
+});
+
+const editorContainerPlaceholderButtonStyles = css({
+  paddingLeft: 8,
+  paddingRight: 8,
+  alignSelf: 'flex-start',
+  display: 'flex',
+  gap: spacing[200],
+  paddingTop: spacing[200],
 });
 
 const DiagramEditor: React.FunctionComponent<{
@@ -92,11 +107,11 @@ const DiagramEditor: React.FunctionComponent<{
   onUndoClick: () => void;
   hasRedo: boolean;
   onRedoClick: () => void;
-  model: unknown;
+  model: StaticModel | null;
+  editErrors?: string[];
   onRetryClick: () => void;
   onCancelClick: () => void;
-  // TODO
-  onApplyClick: (edit: unknown) => void;
+  onApplyClick: (edit: Omit<Edit, 'id' | 'timestamp'>) => void;
 }> = ({
   step,
   hasUndo,
@@ -104,6 +119,7 @@ const DiagramEditor: React.FunctionComponent<{
   hasRedo,
   onRedoClick,
   model,
+  editErrors,
   onRetryClick,
   onCancelClick,
   onApplyClick,
@@ -118,6 +134,43 @@ const DiagramEditor: React.FunctionComponent<{
     }
   }, [applyInput]);
 
+  const applyPlaceholder =
+    (type: 'AddRelationship' | 'RemoveRelationship') => () => {
+      let placeholder = {};
+      switch (type) {
+        case 'AddRelationship':
+          placeholder = {
+            type: 'AddRelationship',
+            relationship: {
+              id: new UUID().toString(),
+              relationship: [
+                {
+                  ns: 'db.sourceCollection',
+                  cardinality: 1,
+                  fields: ['field1'],
+                },
+                {
+                  ns: 'db.targetCollection',
+                  cardinality: 1,
+                  fields: ['field2'],
+                },
+              ],
+              isInferred: false,
+            },
+          };
+          break;
+        case 'RemoveRelationship':
+          placeholder = {
+            type: 'RemoveRelationship',
+            relationshipId: new UUID().toString(),
+          };
+          break;
+        default:
+          throw new Error(`Unknown placeholder ${placeholder}`);
+      }
+      setApplyInput(JSON.stringify(placeholder, null, 2));
+    };
+
   const modelStr = useMemo(() => {
     return JSON.stringify(model, null, 2);
   }, [model]);
@@ -172,6 +225,20 @@ const DiagramEditor: React.FunctionComponent<{
           ></CodemirrorMultilineEditor>
         </div>
         <div className={editorContainerStyles} data-testid="apply-editor">
+          <div className={editorContainerPlaceholderButtonStyles}>
+            <Button
+              onClick={applyPlaceholder('AddRelationship')}
+              data-testid="placeholder-addrelationship-button"
+            >
+              Add relationship
+            </Button>
+            <Button
+              onClick={applyPlaceholder('RemoveRelationship')}
+              data-testid="placeholder-removerelationship-button"
+            >
+              Remove relationship
+            </Button>
+          </div>
           <div>
             <CodemirrorMultilineEditor
               language="json"
@@ -180,7 +247,8 @@ const DiagramEditor: React.FunctionComponent<{
               maxLines={10}
             ></CodemirrorMultilineEditor>
           </div>
-          <div className={editorContainerApplyButtonStyles}>
+          <div className={editorContainerApplyContainerStyles}>
+            {editErrors && <ErrorSummary errors={editErrors} />}
             <Button
               onClick={() => {
                 onApplyClick(JSON.parse(applyInput));
@@ -238,6 +306,7 @@ export default connect(
       model: diagram
         ? selectCurrentModel(getCurrentDiagramFromState(state))
         : null,
+      editErrors: diagram?.editErrors,
     };
   },
   {
diff --git a/packages/compass-data-modeling/src/services/data-model-storage.ts b/packages/compass-data-modeling/src/services/data-model-storage.ts
index 7ba36c519b3..4aef7938400 100644
--- a/packages/compass-data-modeling/src/services/data-model-storage.ts
+++ b/packages/compass-data-modeling/src/services/data-model-storage.ts
@@ -1,4 +1,81 @@
 import { z } from '@mongodb-js/compass-user-data';
+import type { MongoDBJSONSchema } from 'mongodb-schema';
+
+export const RelationshipSideSchema = z.object({
+  ns: z.string(),
+  cardinality: z.number(),
+  fields: z.array(z.string()),
+});
+
+export type RelationshipSide = z.output<typeof RelationshipSideSchema>;
+
+export const RelationshipSchema = z.object({
+  id: z.string().uuid(),
+  relationship: z.tuple([RelationshipSideSchema, RelationshipSideSchema]),
+  isInferred: z.boolean(),
+});
+
+export type Relationship = z.output<typeof RelationshipSchema>;
+
+export const StaticModelSchema = z.object({
+  collections: z.array(
+    z.object({
+      ns: z.string(),
+      jsonSchema: z.custom<MongoDBJSONSchema>((value) => {
+        const isObject = typeof value === 'object' && value !== null;
+        return isObject && 'bsonType' in value;
+      }),
+      indexes: z.array(z.record(z.unknown())),
+      shardKey: z.record(z.unknown()).optional(),
+      displayPosition: z.tuple([z.number(), z.number()]),
+    })
+  ),
+  relationships: z.array(RelationshipSchema),
+});
+
+export type StaticModel = z.output<typeof StaticModelSchema>;
+
+const EditSchemaBase = z.object({
+  id: z.string().uuid(),
+  timestamp: z.string().datetime(),
+});
+
+const EditSchemaVariants = z.discriminatedUnion('type', [
+  z.object({
+    type: z.literal('SetModel'),
+    model: StaticModelSchema,
+  }),
+  z.object({
+    type: z.literal('AddRelationship'),
+    relationship: RelationshipSchema,
+  }),
+  z.object({
+    type: z.literal('RemoveRelationship'),
+    relationshipId: z.string().uuid(),
+  }),
+]);
+
+export const EditSchema = z.intersection(EditSchemaBase, EditSchemaVariants);
+
+export type Edit = z.output<typeof EditSchema>;
+
+export const validateEdit = (
+  edit: unknown
+): { result: true; errors?: never } | { result: false; errors: string[] } => {
+  try {
+    EditSchema.parse(edit);
+    return { result: true };
+  } catch (e) {
+    return {
+      result: false,
+      errors: (e as z.ZodError).issues.map(({ path, message }) =>
+        message === 'Required'
+          ? `'${path}' is required`
+          : `Invalid field '${path}': ${message}`
+      ),
+    };
+  }
+};
 
 export const MongoDBDataModelDescriptionSchema = z.object({
   id: z.string(),
@@ -11,8 +88,7 @@ export const MongoDBDataModelDescriptionSchema = z.object({
    */
   connectionId: z.string().nullable(),
 
-  // TODO: define rest of the schema based on arch doc / tech design
-  edits: z.array(z.unknown()).default([]),
+  edits: z.array(EditSchema).default([]),
 });
 
 export type MongoDBDataModelDescription = z.output<
diff --git a/packages/compass-data-modeling/src/store/analysis-process.ts b/packages/compass-data-modeling/src/store/analysis-process.ts
index d151e45c753..31820d26792 100644
--- a/packages/compass-data-modeling/src/store/analysis-process.ts
+++ b/packages/compass-data-modeling/src/store/analysis-process.ts
@@ -1,10 +1,11 @@
 import type { Reducer } from 'redux';
 import { isAction } from './util';
 import type { DataModelingThunkAction } from './reducer';
-import { analyzeDocuments } from 'mongodb-schema';
+import { analyzeDocuments, type MongoDBJSONSchema } from 'mongodb-schema';
 import { getCurrentDiagramFromState } from './diagram';
 import type { Document } from 'bson';
 import type { AggregationCursor } from 'mongodb';
+import type { Relationship } from '../services/data-model-storage';
 
 export type AnalysisProcessState = {
   currentAnalysisOptions:
@@ -61,9 +62,8 @@ export type AnalysisFinishedAction = {
   type: AnalysisProcessActionTypes.ANALYSIS_FINISHED;
   name: string;
   connectionId: string;
-  // TODO
-  schema: Record<string, unknown>;
-  relations: unknown[];
+  collections: { ns: string; schema: MongoDBJSONSchema }[];
+  relations: Relationship[];
 };
 
 export type AnalysisFailedAction = {
@@ -157,7 +157,7 @@ export function startAnalysis(
     try {
       const dataService =
         services.connections.getDataServiceForConnection(connectionId);
-      const schema = await Promise.all(
+      const collections = await Promise.all(
         namespaces.map(async (ns) => {
           const sample: AggregationCursor<Document> = dataService.sampleCursor(
             ns,
@@ -188,7 +188,7 @@ export function startAnalysis(
             type: AnalysisProcessActionTypes.NAMESPACE_SCHEMA_ANALYZED,
             namespace: ns,
           });
-          return [ns, schema];
+          return { ns, schema };
         })
       );
       if (options.automaticallyInferRelations) {
@@ -201,7 +201,7 @@ export function startAnalysis(
         type: AnalysisProcessActionTypes.ANALYSIS_FINISHED,
         name,
         connectionId,
-        schema: Object.fromEntries(schema),
+        collections,
         relations: [],
       });
       void services.dataModelStorage.save(
diff --git a/packages/compass-data-modeling/src/store/diagram.spec.ts b/packages/compass-data-modeling/src/store/diagram.spec.ts
new file mode 100644
index 00000000000..5fd96312c98
--- /dev/null
+++ b/packages/compass-data-modeling/src/store/diagram.spec.ts
@@ -0,0 +1,197 @@
+import { expect } from 'chai';
+import { type DataModelingStore, setupStore } from '../../test/setup-store';
+import {
+  applyEdit,
+  getCurrentDiagramFromState,
+  openDiagram,
+  redoEdit,
+  undoEdit,
+} from './diagram';
+import type {
+  Edit,
+  MongoDBDataModelDescription,
+  StaticModel,
+} from '../services/data-model-storage';
+import { UUID } from 'bson';
+
+const model: StaticModel = {
+  collections: [
+    {
+      ns: 'collection1',
+      indexes: [],
+      displayPosition: [0, 0],
+      shardKey: {},
+      jsonSchema: { bsonType: 'object' },
+    },
+    {
+      ns: 'collection2',
+      indexes: [],
+      displayPosition: [1, 1],
+      shardKey: {},
+      jsonSchema: { bsonType: 'object' },
+    },
+  ],
+  relationships: [
+    {
+      id: new UUID().toString(),
+      relationship: [
+        {
+          ns: 'db.sourceCollection',
+          cardinality: 1,
+          fields: ['field1'],
+        },
+        {
+          ns: 'db.targetCollection',
+          cardinality: 1,
+          fields: ['field2'],
+        },
+      ],
+      isInferred: false,
+    },
+  ],
+};
+
+const loadedDiagram: MongoDBDataModelDescription = {
+  id: 'diagram-id',
+  name: 'diagram-name',
+  connectionId: 'connection-id',
+  edits: [{ type: 'SetModel', model } as Edit],
+};
+
+describe('Data Modeling store', function () {
+  let store: DataModelingStore;
+
+  beforeEach(function () {
+    store = setupStore();
+  });
+
+  it('openDiagram', function () {
+    store.dispatch(openDiagram(loadedDiagram));
+
+    const diagram = getCurrentDiagramFromState(store.getState());
+    expect(diagram.id).to.equal(loadedDiagram.id);
+    expect(diagram.name).to.equal(loadedDiagram.name);
+    expect(diagram.connectionId).to.equal(loadedDiagram.connectionId);
+    expect(diagram.edits).to.deep.equal(loadedDiagram.edits);
+  });
+
+  describe('applyEdit', function () {
+    it('should apply a valid SetModel edit', function () {
+      store.dispatch(openDiagram(loadedDiagram));
+
+      const edit = {
+        type: 'SetModel' as const,
+        model: {
+          collections: [
+            {
+              ns: 'collection2',
+              indexes: [],
+              displayPosition: [0, 0],
+              shardKey: {},
+              jsonSchema: { bsonType: 'object' },
+            },
+          ] as StaticModel['collections'],
+          relationships: [] as StaticModel['relationships'],
+        },
+      };
+      store.dispatch(applyEdit(edit));
+
+      const state = store.getState();
+      const diagram = getCurrentDiagramFromState(state);
+      expect(state.diagram?.editErrors).to.be.undefined;
+      expect(diagram.edits).to.have.length(2);
+      expect(diagram.edits[0]).to.deep.equal(loadedDiagram.edits[0]);
+      expect(diagram.edits[1]).to.deep.include(edit);
+    });
+
+    it('should apply a valid AddRelationship edit', function () {
+      store.dispatch(openDiagram(loadedDiagram));
+
+      const relationshipId = new UUID().toString();
+      const newRelationship: StaticModel['relationships'][number] = {
+        id: relationshipId,
+        relationship: [
+          {
+            ns: 'db.sourceCollection',
+            cardinality: 1,
+            fields: ['field1'],
+          },
+          {
+            ns: 'db.targetCollection',
+            cardinality: 1,
+            fields: ['field2'],
+          },
+        ],
+        isInferred: false,
+      };
+      store.dispatch(
+        applyEdit({
+          type: 'AddRelationship',
+          relationship: newRelationship,
+        } as Edit)
+      );
+
+      const state = store.getState();
+      const diagram = getCurrentDiagramFromState(state);
+      expect(state.diagram?.editErrors).to.be.undefined;
+      expect(diagram.edits).to.have.length(2);
+      expect(diagram.edits[0]).to.deep.equal(loadedDiagram.edits[0]);
+      expect(diagram.edits[1]).to.deep.include({
+        type: 'AddRelationship',
+        relationship: newRelationship,
+      });
+    });
+
+    it('should not apply invalid AddRelationship edit', function () {
+      store.dispatch(openDiagram(loadedDiagram));
+
+      const edit = {
+        type: 'AddRelationship',
+        relationship: {
+          id: new UUID().toString(),
+          isInferred: false,
+        },
+      } as unknown as Edit;
+      store.dispatch(applyEdit(edit));
+
+      const editErrors = store.getState().diagram?.editErrors;
+      expect(editErrors).to.have.length(1);
+      expect(editErrors && editErrors[0]).to.equal(
+        "'relationship,relationship' is required"
+      );
+      const diagram = getCurrentDiagramFromState(store.getState());
+      expect(diagram.edits).to.deep.equal(loadedDiagram.edits);
+    });
+  });
+
+  it('undo & redo', function () {
+    store.dispatch(openDiagram(loadedDiagram));
+
+    const edit = {
+      type: 'SetModel',
+      model: {
+        ...model,
+        relationships: [] as StaticModel['relationships'],
+      },
+    } as Edit;
+    store.dispatch(applyEdit(edit));
+
+    const diagramAfterEdit = getCurrentDiagramFromState(store.getState());
+    expect(diagramAfterEdit.edits).to.have.length(2);
+    expect(diagramAfterEdit.edits[0]).to.deep.include(loadedDiagram.edits[0]);
+    expect(diagramAfterEdit.edits[1]).to.deep.include(edit);
+
+    store.dispatch(undoEdit());
+
+    const diagramAfterUndo = getCurrentDiagramFromState(store.getState());
+    expect(diagramAfterUndo.edits).to.have.length(1);
+    expect(diagramAfterUndo.edits[0]).to.deep.include(loadedDiagram.edits[0]);
+
+    store.dispatch(redoEdit());
+
+    const diagramAfterRedo = getCurrentDiagramFromState(store.getState());
+    expect(diagramAfterRedo.edits).to.have.length(2);
+    expect(diagramAfterRedo.edits[0]).to.deep.include(loadedDiagram.edits[0]);
+    expect(diagramAfterRedo.edits[1]).to.deep.include(edit);
+  });
+});
diff --git a/packages/compass-data-modeling/src/store/diagram.ts b/packages/compass-data-modeling/src/store/diagram.ts
index 7162de3febb..238de33edc9 100644
--- a/packages/compass-data-modeling/src/store/diagram.ts
+++ b/packages/compass-data-modeling/src/store/diagram.ts
@@ -1,7 +1,12 @@
 import type { Reducer } from 'redux';
 import { UUID } from 'bson';
 import { isAction } from './util';
-import type { MongoDBDataModelDescription } from '../services/data-model-storage';
+import {
+  validateEdit,
+  type Edit,
+  type MongoDBDataModelDescription,
+  type StaticModel,
+} from '../services/data-model-storage';
 import { AnalysisProcessActionTypes } from './analysis-process';
 import { memoize } from 'lodash';
 import type { DataModelingState, DataModelingThunkAction } from './reducer';
@@ -10,10 +15,11 @@ import { showConfirmation, showPrompt } from '@mongodb-js/compass-components';
 export type DiagramState =
   | (Omit<MongoDBDataModelDescription, 'edits'> & {
       edits: {
-        prev: MongoDBDataModelDescription['edits'][];
-        current: MongoDBDataModelDescription['edits'];
-        next: MongoDBDataModelDescription['edits'][];
+        prev: Edit[][];
+        current: Edit[];
+        next: Edit[][];
       };
+      editErrors?: string[];
     })
   | null; // null when no diagram is currently open
 
@@ -22,6 +28,7 @@ export enum DiagramActionTypes {
   DELETE_DIAGRAM = 'data-modeling/diagram/DELETE_DIAGRAM',
   RENAME_DIAGRAM = 'data-modeling/diagram/RENAME_DIAGRAM',
   APPLY_EDIT = 'data-modeling/diagram/APPLY_EDIT',
+  APPLY_EDIT_FAILED = 'data-modeling/diagram/APPLY_EDIT_FAILED',
   UNDO_EDIT = 'data-modeling/diagram/UNDO_EDIT',
   REDO_EDIT = 'data-modeling/diagram/REDO_EDIT',
 }
@@ -44,8 +51,12 @@ export type RenameDiagramAction = {
 
 export type ApplyEditAction = {
   type: DiagramActionTypes.APPLY_EDIT;
-  // TODO
-  edit: unknown;
+  edit: Edit;
+};
+
+export type ApplyEditFailedAction = {
+  type: DiagramActionTypes.APPLY_EDIT_FAILED;
+  errors: string[];
 };
 
 export type UndoEditAction = {
@@ -61,6 +72,7 @@ export type DiagramActions =
   | DeleteDiagramAction
   | RenameDiagramAction
   | ApplyEditAction
+  | ApplyEditFailedAction
   | UndoEditAction
   | RedoEditAction;
 
@@ -92,11 +104,19 @@ export const diagramReducer: Reducer<DiagramState> = (
         prev: [],
         current: [
           {
-            // TODO
             type: 'SetModel',
+            id: new UUID().toString(),
+            timestamp: new Date().toISOString(),
             model: {
-              schema: action.schema,
-              relations: action.relations,
+              collections: action.collections.map((collection) => ({
+                ns: collection.ns,
+                jsonSchema: collection.schema,
+                // TODO
+                indexes: [],
+                shardKey: undefined,
+                displayPosition: [0, 0],
+              })),
+              relationships: action.relations,
             },
           },
         ],
@@ -124,6 +144,13 @@ export const diagramReducer: Reducer<DiagramState> = (
         current: [...state.edits.current, action.edit],
         next: [],
       },
+      editErrors: undefined,
+    };
+  }
+  if (isAction(action, DiagramActionTypes.APPLY_EDIT_FAILED)) {
+    return {
+      ...state,
+      editErrors: action.errors,
     };
   }
   if (isAction(action, DiagramActionTypes.UNDO_EDIT)) {
@@ -172,10 +199,27 @@ export function redoEdit(): DataModelingThunkAction<void, RedoEditAction> {
 }
 
 export function applyEdit(
-  edit: unknown
-): DataModelingThunkAction<void, ApplyEditAction> {
+  rawEdit: Omit<Edit, 'id' | 'timestamp'>
+): DataModelingThunkAction<void, ApplyEditAction | ApplyEditFailedAction> {
   return (dispatch, getState, { dataModelStorage }) => {
-    dispatch({ type: DiagramActionTypes.APPLY_EDIT, edit });
+    const edit = {
+      ...rawEdit,
+      id: new UUID().toString(),
+      timestamp: new Date().toISOString(),
+      // TS has a problem recognizing the discriminated union
+    } as Edit;
+    const { result: isValid, errors } = validateEdit(edit);
+    if (!isValid) {
+      dispatch({
+        type: DiagramActionTypes.APPLY_EDIT_FAILED,
+        errors,
+      });
+      return;
+    }
+    dispatch({
+      type: DiagramActionTypes.APPLY_EDIT,
+      edit,
+    });
     void dataModelStorage.save(getCurrentDiagramFromState(getState()));
   };
 }
@@ -227,22 +271,64 @@ export function renameDiagram(
   };
 }
 
-// TODO
-function _applyEdit(model: any, edit: any) {
-  if (edit && 'type' in edit) {
-    if (edit.type === 'SetModel') {
-      return edit.model;
+function _applyEdit(edit: Edit, model?: StaticModel): StaticModel {
+  if (edit.type === 'SetModel') {
+    return edit.model;
+  }
+  if (!model) {
+    throw new Error('Editing a model that has not been initialized');
+  }
+  switch (edit.type) {
+    case 'AddRelationship': {
+      return {
+        ...model,
+        relationships: [...model.relationships, edit.relationship],
+      };
+    }
+    case 'RemoveRelationship': {
+      return {
+        ...model,
+        relationships: model.relationships.filter(
+          (relationship) => relationship.id !== edit.relationshipId
+        ),
+      };
+    }
+    default: {
+      return model;
     }
   }
-  return model;
 }
 
-export function getCurrentModel(diagram: MongoDBDataModelDescription): unknown {
-  let model;
-  for (const edit of diagram.edits) {
-    model = _applyEdit(model, edit);
+export function getCurrentModel(
+  description: MongoDBDataModelDescription
+): StaticModel {
+  // Get the last 'SetModel' edit.
+  const reversedSetModelEditIndex = description.edits
+    .slice()
+    .reverse()
+    .findIndex((edit) => edit.type === 'SetModel');
+  if (reversedSetModelEditIndex === -1) {
+    throw new Error('No diagram model found.');
   }
-  return model;
+
+  // Calculate the actual index in the original array.
+  const lastSetModelEditIndex =
+    description.edits.length - 1 - reversedSetModelEditIndex;
+
+  // Start with the StaticModel from the last `SetModel` edit.
+  const lastSetModelEdit = description.edits[lastSetModelEditIndex];
+  if (lastSetModelEdit.type !== 'SetModel') {
+    throw new Error('Something went wrong, last edit is not a SetModel');
+  }
+  let currentModel = lastSetModelEdit.model;
+
+  // Apply all subsequent edits after the last `SetModel` edit.
+  for (let i = lastSetModelEditIndex + 1; i < description.edits.length; i++) {
+    const edit = description.edits[i];
+    currentModel = _applyEdit(edit, currentModel);
+  }
+
+  return currentModel;
 }
 
 export function getCurrentDiagramFromState(
diff --git a/packages/compass-e2e-tests/tests/data-modeling-tab.test.ts b/packages/compass-e2e-tests/tests/data-modeling-tab.test.ts
index 3b4947d6329..d4d62b21ec9 100644
--- a/packages/compass-e2e-tests/tests/data-modeling-tab.test.ts
+++ b/packages/compass-e2e-tests/tests/data-modeling-tab.test.ts
@@ -84,13 +84,17 @@ describe('Data Modeling tab', function () {
     const text = await browser.getCodemirrorEditorText(
       Selectors.DataModelPreview
     );
-    expect(text).to.include('"test.testCollection1": ');
-    expect(text).to.include('"test.testCollection2": ');
+
+    expect(text).to.include('"ns": "test.testCollection1"');
+    expect(text).to.include('"ns": "test.testCollection2"');
 
     // Apply change to the model
     const newModel = {
       type: 'SetModel',
-      model: { schema: { coll1: {}, coll2: {} } },
+      model: {
+        collections: [],
+        relationships: [],
+      },
     };
     const newPreview = JSON.stringify(newModel.model, null, 2);
     await browser.setCodemirrorEditorValue(
@@ -112,8 +116,8 @@ describe('Data Modeling tab', function () {
         Selectors.DataModelPreview
       );
       return (
-        textAfterUndo.includes('"test.testCollection1": ') &&
-        textAfterUndo.includes('"test.testCollection2": ')
+        textAfterUndo.includes('"ns": "test.testCollection1"') &&
+        textAfterUndo.includes('"ns": "test.testCollection2"')
       );
     });
 
diff --git a/packages/compass-preferences-model/package.json b/packages/compass-preferences-model/package.json
index 21c76dd4319..08c7e16b5cf 100644
--- a/packages/compass-preferences-model/package.json
+++ b/packages/compass-preferences-model/package.json
@@ -59,8 +59,7 @@
     "js-yaml": "^4.1.0",
     "lodash": "^4.17.21",
     "react": "^17.0.2",
-    "yargs-parser": "^21.1.1",
-    "zod": "^3.22.3"
+    "yargs-parser": "^21.1.1"
   },
   "devDependencies": {
     "@mongodb-js/eslint-config-compass": "^1.3.8",
diff --git a/packages/compass-preferences-model/src/global-config.ts b/packages/compass-preferences-model/src/global-config.ts
index 179ccc2e34b..53990d5c770 100644
--- a/packages/compass-preferences-model/src/global-config.ts
+++ b/packages/compass-preferences-model/src/global-config.ts
@@ -7,7 +7,7 @@ import yargsParser from 'yargs-parser';
 import { kebabCase } from 'lodash';
 import type { AllPreferences } from './preferences-schema';
 import { allPreferencesProps } from './preferences-schema';
-import type { z } from 'zod';
+import type { z } from '@mongodb-js/compass-user-data';
 
 import { createLogger } from '@mongodb-js/compass-logging';
 const { log, mongoLogId } = createLogger('COMPASS-PREFERENCES');
diff --git a/packages/compass-preferences-model/src/preferences-persistent-storage.ts b/packages/compass-preferences-model/src/preferences-persistent-storage.ts
index d4973a32cd2..4507f7ccacf 100644
--- a/packages/compass-preferences-model/src/preferences-persistent-storage.ts
+++ b/packages/compass-preferences-model/src/preferences-persistent-storage.ts
@@ -1,5 +1,4 @@
-import type { z } from 'zod';
-import { UserData } from '@mongodb-js/compass-user-data';
+import { type z, UserData } from '@mongodb-js/compass-user-data';
 import {
   getDefaultsForStoredPreferences,
   getPreferencesValidator,
diff --git a/packages/compass-preferences-model/src/preferences-schema.tsx b/packages/compass-preferences-model/src/preferences-schema.tsx
index 9acd7a873a7..7570e09c0eb 100644
--- a/packages/compass-preferences-model/src/preferences-schema.tsx
+++ b/packages/compass-preferences-model/src/preferences-schema.tsx
@@ -1,5 +1,5 @@
 import React from 'react';
-import { z } from 'zod';
+import { z } from '@mongodb-js/compass-user-data';
 import {
   type FeatureFlagDefinition,
   type FeatureFlags,
diff --git a/packages/compass-preferences-model/src/preferences.ts b/packages/compass-preferences-model/src/preferences.ts
index 5d7bf63cdd9..9d20d7d32a8 100644
--- a/packages/compass-preferences-model/src/preferences.ts
+++ b/packages/compass-preferences-model/src/preferences.ts
@@ -1,4 +1,4 @@
-import { z } from 'zod';
+import { z } from '@mongodb-js/compass-user-data';
 import { type Logger } from '@mongodb-js/compass-logging';
 
 import type { ParsedGlobalPreferencesResult } from './global-config';
diff --git a/packages/compass-preferences-model/src/user-storage.spec.ts b/packages/compass-preferences-model/src/user-storage.spec.ts
index 0b1700b4dfe..9c1dadd264e 100644
--- a/packages/compass-preferences-model/src/user-storage.spec.ts
+++ b/packages/compass-preferences-model/src/user-storage.spec.ts
@@ -1,4 +1,4 @@
-import { z } from 'zod';
+import { z } from '@mongodb-js/compass-user-data';
 import { expect } from 'chai';
 import os from 'os';
 import path from 'path';
diff --git a/packages/compass-preferences-model/src/user-storage.ts b/packages/compass-preferences-model/src/user-storage.ts
index 3252151e0bd..044d6b04b30 100644
--- a/packages/compass-preferences-model/src/user-storage.ts
+++ b/packages/compass-preferences-model/src/user-storage.ts
@@ -1,4 +1,4 @@
-import { z } from 'zod';
+import { z } from '@mongodb-js/compass-user-data';
 import { UUID } from 'bson';
 import { UserData } from '@mongodb-js/compass-user-data';
 
diff --git a/packages/compass-user-data/package.json b/packages/compass-user-data/package.json
index f9c5d72042f..49cf877dbeb 100644
--- a/packages/compass-user-data/package.json
+++ b/packages/compass-user-data/package.json
@@ -52,7 +52,7 @@
     "@mongodb-js/compass-logging": "^1.6.9",
     "@mongodb-js/compass-utils": "^0.8.8",
     "write-file-atomic": "^5.0.1",
-    "zod": "^3.22.3"
+    "zod": "^3.25.17"
   },
   "devDependencies": {
     "@mongodb-js/eslint-config-compass": "^1.3.8",