[One Workflow] New Cases action menu group under Kibana (elastic#261964)

## Summary

Part of: elastic/security-team#15982.
(Resolves requirement `#4`)

This change introduces a dedicated **`StepCategory.KibanaCases`**
(`kibana.cases`) so Cases workflow steps are grouped under **Kibana →
Cases** in the workflow actions menu instead of sitting in the flat
Kibana list.

**Actions menu (`workflows_management`)**

- Builds a **Cases** subgroup (`id: kibana.cases`) under the Kibana
group via **`nestedGroups`**, then merges any non-empty nested group
into the parent’s **`options`** so the UI stays a normal tree of groups.
- Assigns **`pathIds`** on every group (full path from the root) so
choosing a nested group from **search** opens the correct depth (Kibana
→ Cases → …) instead of only appending the last segment.
- **`ActionsMenu`** uses `selectedOption.pathIds ?? [...currentPath,
id]` when entering a group.

**Shared spec**

- Adds **`StepCategory.KibanaCases`** in `@kbn/kbn-workflows` so step
definitions and UI routing can target the Cases bucket explicitly.

**Cases plugin**

- Updates all Cases **common workflow step** definitions to use
**`StepCategory.KibanaCases`** instead of **`StepCategory.Kibana`**.

**Agent builder**

- **`get_step_definitions_tool`**: maps connector types **`cases.*`** →
**`KibanaCases`** and keeps **`kibana.*`** → **`Kibana`**.

**Tests**

- Extends **`get_action_options.test.ts`** for nested Cases, empty Cases
group hidden, **`pathIds`**, and ordering expectations.

---

## Demo


https://github.com/user-attachments/assets/dc14c35d-f63c-4165-9c23-1590a22edf80

---

Author: semd

src/platform/packages/shared/kbn-workflows/spec/step_definition_types.ts

@@ -15,6 +15,7 @@ export enum StepCategory {
   External = 'external',
   Ai = 'ai',
   Kibana = 'kibana',
+  KibanaCases = 'kibana.cases',
   Data = 'data',
   FlowControl = 'flowControl',
 }

src/platform/plugins/shared/workflows_management/public/features/actions_menu_popover/lib/get_action_options.test.ts

@@ -166,6 +166,126 @@ describe('getActionOptions', () => {
     }
   });
 
+  it('should not show Cases nested group when no cases steps are registered', () => {
+    const result = getActionOptions(mockEuiTheme, mockWorkflowsExtensions);
+    const kibanaGroup = result.find((group) => group.id === 'kibana');
+
+    expect(kibanaGroup).toBeDefined();
+    if (kibanaGroup && isActionGroup(kibanaGroup)) {
+      expect(kibanaGroup.options).toHaveLength(0);
+      expect(kibanaGroup.options.find((opt) => opt.id === 'kibana.cases')).toBeUndefined();
+    }
+  });
+
+  it('should place KibanaCases steps in nested Cases group under Kibana', () => {
+    const mockConnector = {
+      type: 'cases.createCase',
+      description: 'Create case',
+    };
+
+    const mockStepDefinition = {
+      id: 'cases.createCase',
+      label: 'Create case',
+      description: 'Create a case',
+      icon: 'casesApp',
+      category: StepCategory.KibanaCases,
+      inputSchema: z.object({}),
+      outputSchema: z.object({}),
+    };
+
+    (getAllConnectors as jest.Mock).mockReturnValue([mockConnector]);
+    mockWorkflowsExtensions.getStepDefinition.mockReturnValue(mockStepDefinition as any);
+
+    const result = getActionOptions(mockEuiTheme, mockWorkflowsExtensions);
+    const kibanaGroup = result.find((group) => group.id === 'kibana');
+
+    expect(kibanaGroup).toBeDefined();
+    if (kibanaGroup && isActionGroup(kibanaGroup)) {
+      expect(kibanaGroup.options).toHaveLength(1);
+      const casesNested = kibanaGroup.options[0];
+      expect(casesNested.id).toBe('kibana.cases');
+      if (isActionGroup(casesNested)) {
+        expect(casesNested.options).toHaveLength(1);
+        expect(casesNested.options[0].id).toBe('cases.createCase');
+      }
+    }
+  });
+
+  it('should set pathIds on groups for navigation from search', () => {
+    const mockConnector = {
+      type: 'cases.createCase',
+      description: 'Create case',
+    };
+
+    const mockStepDefinition = {
+      id: 'cases.createCase',
+      label: 'Create case',
+      description: 'Create a case',
+      icon: 'casesApp',
+      category: StepCategory.KibanaCases,
+      inputSchema: z.object({}),
+      outputSchema: z.object({}),
+    };
+
+    (getAllConnectors as jest.Mock).mockReturnValue([mockConnector]);
+    mockWorkflowsExtensions.getStepDefinition.mockReturnValue(mockStepDefinition as any);
+
+    const result = getActionOptions(mockEuiTheme, mockWorkflowsExtensions);
+    const kibanaGroup = result.find((group) => group.id === 'kibana');
+
+    expect(kibanaGroup).toBeDefined();
+    if (kibanaGroup && isActionGroup(kibanaGroup)) {
+      expect(kibanaGroup.pathIds).toEqual(['kibana']);
+      const casesNested = kibanaGroup.options.find((opt) => opt.id === 'kibana.cases');
+      expect(casesNested).toBeDefined();
+      if (casesNested && isActionGroup(casesNested)) {
+        expect(casesNested.pathIds).toEqual(['kibana', 'kibana.cases']);
+      }
+    }
+  });
+
+  it('should list nested Cases group before other Kibana options when both are present', () => {
+    const mockConnectors = [
+      {
+        type: 'kibana.saved_object',
+        description: 'Saved Object',
+        summary: 'Kibana Summary',
+      },
+      {
+        type: 'cases.createCase',
+        description: 'Create case',
+      },
+    ];
+
+    const mockCasesStepDefinition = {
+      id: 'cases.createCase',
+      label: 'Create case',
+      description: 'Create a case',
+      icon: 'casesApp',
+      category: StepCategory.KibanaCases,
+      inputSchema: z.object({}),
+      outputSchema: z.object({}),
+    };
+
+    (getAllConnectors as jest.Mock).mockReturnValue(mockConnectors);
+    mockWorkflowsExtensions.getStepDefinition.mockImplementation((type: string) => {
+      if (type === 'cases.createCase') {
+        return mockCasesStepDefinition as any;
+      }
+      return undefined;
+    });
+
+    const result = getActionOptions(mockEuiTheme, mockWorkflowsExtensions);
+    const kibanaGroup = result.find((group) => group.id === 'kibana');
+
+    expect(kibanaGroup).toBeDefined();
+    if (kibanaGroup && isActionGroup(kibanaGroup)) {
+      expect(kibanaGroup.options).toHaveLength(2);
+      expect(kibanaGroup.options[0].id).toBe('kibana.cases');
+      expect(kibanaGroup.options[1].id).toBe('kibana.saved_object');
+    }
+  });
+
   it('should add elasticsearch connectors to elasticsearch group', () => {
     const mockConnector = {
       type: 'elasticsearch.search',

src/platform/plugins/shared/workflows_management/public/features/actions_menu_popover/lib/get_action_options.ts

@@ -81,7 +81,19 @@ export function getActionOptions(
     options: [...builtInTriggerOptions, ...registeredTriggerOptions],
   };
 
-  const kibanaGroup: ActionOptionData = {
+  const kibanaCasesGroup: ActionGroup = {
+    iconType: 'briefcase',
+    id: 'kibana.cases',
+    label: i18n.translate('workflows.actionsMenu.kibanaCases', {
+      defaultMessage: 'Cases',
+    }),
+    description: i18n.translate('workflows.actionsMenu.kibanaCasesDescription', {
+      defaultMessage: 'Create and manage cases from your workflow',
+    }),
+    options: [],
+  };
+
+  const kibanaGroup: ActionGroup = {
     iconType: 'logoKibana',
     id: 'kibana',
     label: i18n.translate('workflows.actionsMenu.kibana', {
@@ -91,6 +103,7 @@ export function getActionOptions(
       defaultMessage: 'Work with Kibana data and features directly from your workflow',
     }),
     options: [],
+    nestedGroups: [kibanaCasesGroup],
   };
   const externalGroup: ActionOptionData = {
     iconType: 'plugs',
@@ -234,6 +247,7 @@ export function getActionOptions(
     [StepCategory.External]: externalGroup,
     [StepCategory.Ai]: aiGroup,
     [StepCategory.Kibana]: kibanaGroup,
+    [StepCategory.KibanaCases]: kibanaCasesGroup,
     [StepCategory.Data]: dataTransformationGroup,
     [StepCategory.FlowControl]: flowControlGroup,
   };
@@ -309,7 +323,17 @@ export function getActionOptions(
     }
   }
 
-  return [
+  for (const group of Object.values(stepGroups)) {
+    if (group.nestedGroups) {
+      for (const nestedGroup of group.nestedGroups) {
+        if (nestedGroup.options.length > 0) {
+          group.options.unshift(nestedGroup);
+        }
+      }
+    }
+  }
+
+  const topLevelOptions: ActionOptionData[] = [
     triggersGroup,
     elasticSearchGroup,
     kibanaGroup,
@@ -318,6 +342,24 @@ export function getActionOptions(
     externalGroup,
     flowControlGroup,
   ];
+  assignActionPathIds(topLevelOptions);
+  return topLevelOptions;
+}
+
+/**
+ * Sets `pathIds` on every nested group so navigation works when a group is chosen from search
+ * (full ancestor chain, not only the clicked row's id).
+ */
+function assignActionPathIds(
+  options: ActionOptionData[],
+  parentPath: readonly string[] = []
+): void {
+  for (const opt of options) {
+    if ('options' in opt) {
+      opt.pathIds = [...parentPath, opt.id];
+      assignActionPathIds(opt.options, opt.pathIds);
+    }
+  }
 }
 
 export function flattenOptions(options: ActionOptionData[]): ActionOptionData[] {

src/platform/plugins/shared/workflows_management/public/features/actions_menu_popover/types.ts

@@ -17,11 +17,17 @@ interface ActionBase {
   instancesLabel?: string;
   iconColor?: string;
   stability?: StepStabilityLevel;
+  /**
+   * Ids from the root menu down through this row (for groups: path to open this group).
+   * Set in `getActionOptions` for O(1) navigation when selecting from search.
+   */
+  pathIds?: readonly string[];
 }
 
 export interface ActionGroup extends ActionBase {
   iconType: IconType;
   options: ActionOptionData[];
+  nestedGroups?: ActionGroup[];
 }
 
 export interface ActionConnectorGroup extends ActionBase {

src/platform/plugins/shared/workflows_management/public/features/actions_menu_popover/ui/actions_menu.tsx

@@ -146,7 +146,8 @@ export function ActionsMenu({ onActionSelected }: ActionsMenuProps) {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   const handleChange = (_: Array<ActionOptionData>, __: any, selectedOption: ActionOptionData) => {
     if (isActionGroup(selectedOption)) {
-      setCurrentPath([...currentPath, selectedOption.id]);
+      const nextPath = selectedOption.pathIds ?? [...currentPath, selectedOption.id];
+      setCurrentPath([...nextPath]);
       setSearchTerm('');
       setOptions(selectedOption.options);
     } else {

src/platform/plugins/shared/workflows_management/server/agent_builder/tools/get_step_definitions_tool.ts

@@ -61,7 +61,8 @@ export async function resolveConnectors(
 }
 
 function categorizeConnectorType(type: string): StepCategory {
-  if (type.startsWith('kibana.') || type.startsWith('cases.')) return StepCategory.Kibana;
+  if (type.startsWith('kibana.')) return StepCategory.Kibana;
+  if (type.startsWith('cases.')) return StepCategory.KibanaCases;
   if (type.startsWith('elasticsearch.')) return StepCategory.Elasticsearch;
   if (type.startsWith('ai.')) return StepCategory.Ai;
   if (type.startsWith('data.')) return StepCategory.Data;

x-pack/platform/plugins/shared/cases/common/workflows/steps/add_alerts.ts

@@ -41,7 +41,7 @@ export const addAlertsStepCommonDefinition: CommonStepDefinition<
   AddAlertsStepOutputSchema
 > = {
   id: AddAlertsStepTypeId,
-  category: StepCategory.Kibana,
+  category: StepCategory.KibanaCases,
   label: i18n.ADD_ALERTS_STEP_LABEL,
   description: i18n.ADD_ALERTS_STEP_DESCRIPTION,
   documentation: {

x-pack/platform/plugins/shared/cases/common/workflows/steps/add_comment.ts

@@ -34,7 +34,7 @@ export const addCommentStepCommonDefinition: CommonStepDefinition<
   AddCommentStepOutputSchema
 > = {
   id: AddCommentStepTypeId,
-  category: StepCategory.Kibana,
+  category: StepCategory.KibanaCases,
   label: i18n.ADD_COMMENT_STEP_LABEL,
   description: i18n.ADD_COMMENT_STEP_DESCRIPTION,
   documentation: {

x-pack/platform/plugins/shared/cases/common/workflows/steps/add_events.ts

@@ -39,7 +39,7 @@ export const addEventsStepCommonDefinition: CommonStepDefinition<
   AddEventsStepOutputSchema
 > = {
   id: AddEventsStepTypeId,
-  category: StepCategory.Kibana,
+  category: StepCategory.KibanaCases,
   label: i18n.ADD_EVENTS_STEP_LABEL,
   description: i18n.ADD_EVENTS_STEP_DESCRIPTION,
   documentation: {

x-pack/platform/plugins/shared/cases/common/workflows/steps/add_observables.ts

@@ -44,7 +44,7 @@ export const addObservablesStepCommonDefinition: CommonStepDefinition<
   AddObservablesStepOutputSchema
 > = {
   id: AddObservablesStepTypeId,
-  category: StepCategory.Kibana,
+  category: StepCategory.KibanaCases,
   label: i18n.ADD_OBSERVABLES_STEP_LABEL,
   description: i18n.ADD_OBSERVABLES_STEP_DESCRIPTION,
   documentation: {