[ML] Fixes display of model state in trained models list with starting and stopping deployments (#188847)

## Summary

Fixes #188035 and #181093

<img width="1434" alt="image"
src="https://github.com/user-attachments/assets/6c14afa3-2908-45ff-a68d-88ee18f18964">



### Checklist


- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

x-pack/plugins/ml/common/types/trained_models.ts

@@ -176,6 +176,7 @@ export interface TrainedModelDeploymentStatsResponse {
     threads_per_allocation: number;
     number_of_allocations: number;
   }>;
+  reason?: string;
 }
 
 export interface AllocatedModel {

x-pack/plugins/ml/public/application/model_management/get_model_state.test.tsx

@@ -0,0 +1,119 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { getModelDeploymentState } from './get_model_state';
+import { MODEL_STATE } from '@kbn/ml-trained-models-utils';
+import type { ModelItem } from './models_list';
+
+describe('getModelDeploymentState', () => {
+  it('returns STARTED if any deployment is in STARTED state', () => {
+    const model = {
+      stats: {
+        model_id: '.elser_model_2',
+        model_size_stats: {
+          model_size_bytes: 438123914,
+          required_native_memory_bytes: 2101346304,
+        },
+
+        deployment_stats: [
+          {
+            deployment_id: '.elser_model_2_01',
+            model_id: '.elser_model_2',
+            state: 'starting',
+          },
+          {
+            deployment_id: '.elser_model_2',
+            model_id: '.elser_model_2',
+            state: 'started',
+            allocation_status: {
+              allocation_count: 1,
+              target_allocation_count: 1,
+              state: 'fully_allocated',
+            },
+          },
+        ],
+      },
+    } as unknown as ModelItem;
+    const result = getModelDeploymentState(model);
+    expect(result).toEqual(MODEL_STATE.STARTED);
+  });
+
+  it('returns MODEL_STATE.STARTING if any deployment is in STARTING state', () => {
+    const model = {
+      stats: {
+        model_id: '.elser_model_2',
+        model_size_stats: {
+          model_size_bytes: 438123914,
+          required_native_memory_bytes: 2101346304,
+        },
+
+        deployment_stats: [
+          {
+            deployment_id: '.elser_model_2',
+            model_id: '.elser_model_2',
+            state: 'stopping',
+          },
+          {
+            deployment_id: '.elser_model_2_01',
+            model_id: '.elser_model_2',
+            state: 'starting',
+          },
+          {
+            deployment_id: '.elser_model_2',
+            model_id: '.elser_model_2',
+            state: 'stopping',
+          },
+        ],
+      },
+    } as unknown as ModelItem;
+    const result = getModelDeploymentState(model);
+    expect(result).toEqual(MODEL_STATE.STARTING);
+  });
+
+  it('returns MODEL_STATE.STOPPING if every deployment is in STOPPING state', () => {
+    const model = {
+      stats: {
+        model_id: '.elser_model_2',
+        model_size_stats: {
+          model_size_bytes: 438123914,
+          required_native_memory_bytes: 2101346304,
+        },
+
+        deployment_stats: [
+          {
+            deployment_id: '.elser_model_2',
+            model_id: '.elser_model_2',
+            state: 'stopping',
+          },
+          {
+            deployment_id: '.elser_model_2_01',
+            model_id: '.elser_model_2',
+            state: 'stopping',
+          },
+        ],
+      },
+    } as unknown as ModelItem;
+    const result = getModelDeploymentState(model);
+    expect(result).toEqual(MODEL_STATE.STOPPING);
+  });
+
+  it('returns undefined for empty deployment stats', () => {
+    const model = {
+      stats: {
+        model_id: '.elser_model_2',
+        model_size_stats: {
+          model_size_bytes: 438123914,
+          required_native_memory_bytes: 2101346304,
+        },
+
+        deployment_stats: [],
+      },
+    } as unknown as ModelItem;
+    const result = getModelDeploymentState(model);
+    expect(result).toEqual(undefined);
+  });
+});

x-pack/plugins/ml/public/application/model_management/get_model_state.tsx

@@ -5,13 +5,34 @@
  * 2.0.
  */
 
-import type { ModelState } from '@kbn/ml-trained-models-utils';
-import { MODEL_STATE } from '@kbn/ml-trained-models-utils';
+import { DEPLOYMENT_STATE, MODEL_STATE, type ModelState } from '@kbn/ml-trained-models-utils';
 import type { EuiHealthProps } from '@elastic/eui';
 import { i18n } from '@kbn/i18n';
+import type { ModelItem } from './models_list';
+
+/**
+ * Resolves result model state based on the state of each deployment.
+ *
+ * If at least one deployment is in the STARTED state, the model state is STARTED.
+ * Then if none of the deployments are in the STARTED state, but at least one is in the STARTING state, the model state is STARTING.
+ * If all deployments are in the STOPPING state, the model state is STOPPING.
+ */
+export const getModelDeploymentState = (model: ModelItem): ModelState | undefined => {
+  if (!model.stats?.deployment_stats?.length) return;
+
+  if (model.stats?.deployment_stats?.some((v) => v.state === DEPLOYMENT_STATE.STARTED)) {
+    return MODEL_STATE.STARTED;
+  }
+  if (model.stats?.deployment_stats?.some((v) => v.state === DEPLOYMENT_STATE.STARTING)) {
+    return MODEL_STATE.STARTING;
+  }
+  if (model.stats?.deployment_stats?.every((v) => v.state === DEPLOYMENT_STATE.STOPPING)) {
+    return MODEL_STATE.STOPPING;
+  }
+};
 
 export const getModelStateColor = (
-  state: ModelState
+  state: ModelState | undefined
 ): { color: EuiHealthProps['color']; name: string } | null => {
   switch (state) {
     case MODEL_STATE.DOWNLOADED:

x-pack/plugins/ml/public/application/model_management/models_list.tsx

@@ -50,7 +50,7 @@ import { isDefined } from '@kbn/ml-is-defined';
 import { useStorage } from '@kbn/ml-local-storage';
 import { dynamic } from '@kbn/shared-ux-utility';
 import useMountedState from 'react-use/lib/useMountedState';
-import { getModelStateColor } from './get_model_state_color';
+import { getModelStateColor, getModelDeploymentState } from './get_model_state';
 import { ML_ELSER_CALLOUT_DISMISSED } from '../../../common/types/storage';
 import { TechnicalPreviewBadge } from '../components/technical_preview_badge';
 import { useModelActions } from './model_actions';
@@ -88,7 +88,11 @@ export type ModelItem = TrainedModelConfigResponse & {
   origin_job_exists?: boolean;
   deployment_ids: string[];
   putModelConfig?: object;
-  state: ModelState;
+  state: ModelState | undefined;
+  /**
+   * Description of the current model state
+   */
+  stateDescription?: string;
   recommended?: boolean;
   /**
    * Model name, e.g. elser
@@ -374,14 +378,17 @@ export const ModelsList: FC<Props> = ({
             ...modelStats[0],
             deployment_stats: modelStats.map((d) => d.deployment_stats).filter(isDefined),
           };
+
+          // Extract deployment ids from deployment stats
           model.deployment_ids = modelStats
             .map((v) => v.deployment_stats?.deployment_id)
             .filter(isDefined);
-          model.state = model.stats.deployment_stats?.some(
-            (v) => v.state === DEPLOYMENT_STATE.STARTED
-          )
-            ? DEPLOYMENT_STATE.STARTED
-            : null;
+
+          model.state = getModelDeploymentState(model);
+          model.stateDescription = model.stats.deployment_stats.reduce((acc, c) => {
+            if (acc) return acc;
+            return c.reason ?? '';
+          }, '');
         });
 
         const elasticModels = models.filter((model) =>