feat(core): Coordinate manual workflow activation and deactivation in multi-main scenario (#7643)

Followup to #7566 | Story: https://linear.app/n8n/issue/PAY-926

### Manual workflow activation and deactivation

In a multi-main scenario, if the user manually activates or deactivates
a workflow, the process (whether leader or follower) that handles the
PATCH request and updates its internal state should send a message into
the command channel, so that all other main processes update their
internal state accordingly:

- Add to `ActiveWorkflows` if activating
- Remove from `ActiveWorkflows` if deactivating
- Remove and re-add to `ActiveWorkflows` if the update did not change
activation status.

After updating their internal state, if activating or deactivating, the
recipient main processes should push a message to all connected
frontends so that these can update their stores and so reflect the value
in the UI.

### Workflow activation errors

On failure to activate a workflow, the main instance should record the
error in Redis - main instances should always pull activation errors
from Redis in a multi-main scenario.

### Leadership change

On leadership change...

- The old leader should stop pruning and the new leader should start
pruning.
- The old leader should remove trigger- and poller-based workflows and
the new leader should add them.

packages/cli/src/workflows/workflows.services.ts

@@ -30,6 +30,7 @@ import { isStringArray, isWorkflowIdValid } from '@/utils';
 import { WorkflowHistoryService } from './workflowHistory/workflowHistory.service.ee';
 import { BinaryDataService } from 'n8n-core';
 import { Logger } from '@/Logger';
+import { MultiMainSetup } from '@/services/orchestration/main/MultiMainSetup.ee';
 import { SharedWorkflowRepository } from '@db/repositories/sharedWorkflow.repository';
 import { WorkflowTagMappingRepository } from '@db/repositories/workflowTagMapping.repository';
 import { ExecutionRepository } from '@db/repositories/execution.repository';
@@ -212,6 +213,8 @@ export class WorkflowsService {
 			);
 		}
 
+		const oldState = shared.workflow.active;
+
 		if (
 			!forceSave &&
 			workflow.versionId !== '' &&
@@ -255,9 +258,14 @@ export class WorkflowsService {
 
 		await Container.get(ExternalHooks).run('workflow.update', [workflow]);
 
+		/**
+		 * If the workflow being updated is stored as `active`, remove it from
+		 * active workflows in memory, and re-add it after the update.
+		 *
+		 * If a trigger or poller in the workflow was updated, the new value
+		 * will take effect only on removing and re-adding.
+		 */
 		if (shared.workflow.active) {
-			// When workflow gets saved always remove it as the triggers could have been
-			// changed and so the changes would not take effect
 			await Container.get(ActiveWorkflowRunner).remove(workflowId);
 		}
 
@@ -364,6 +372,21 @@ export class WorkflowsService {
 			}
 		}
 
+		if (config.getEnv('executions.mode') === 'queue' && config.getEnv('multiMainSetup.enabled')) {
+			const multiMainSetup = Container.get(MultiMainSetup);
+
+			await multiMainSetup.init();
+
+			if (multiMainSetup.isEnabled) {
+				await Container.get(MultiMainSetup).broadcastWorkflowActiveStateChanged({
+					workflowId,
+					oldState,
+					newState: updatedWorkflow.active,
+					versionId: shared.workflow.versionId,
+				});
+			}
+		}
+
 		return updatedWorkflow;
 	}