feat: surface workflow diagnostics

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/main/AryxAppService.ts

@@ -2504,6 +2504,21 @@ export class AryxAppService extends EventEmitter<AppServiceEvents> {
           agentName: event.agentName,
         });
         return;
+      case 'workflow-diagnostic':
+        this.emitSessionEvent({
+          sessionId,
+          kind: 'workflow-diagnostic',
+          occurredAt,
+          agentId: event.agentId,
+          agentName: event.agentName,
+          diagnosticSeverity: event.severity,
+          diagnosticKind: event.diagnosticKind,
+          diagnosticMessage: event.message,
+          executorId: event.executorId,
+          subworkflowId: event.subworkflowId,
+          exceptionType: event.exceptionType,
+        });
+        return;
       case 'assistant-usage':
         this.emitSessionEvent({
           sessionId,

src/main/sidecar/runTurnPending.ts

@@ -15,6 +15,7 @@ import type {
   AssistantUsageEvent,
   AssistantIntentEvent,
   ReasoningDeltaEvent,
+  WorkflowDiagnosticEvent,
 } from '@shared/contracts/sidecar';
 import type { ChatMessageRecord } from '@shared/domain/session';
 
@@ -27,7 +28,8 @@ export type TurnScopedEvent =
   | PendingMessagesModifiedEvent
   | AssistantUsageEvent
   | AssistantIntentEvent
-  | ReasoningDeltaEvent;
+  | ReasoningDeltaEvent
+  | WorkflowDiagnosticEvent;
 
 export interface RunTurnPendingCommand {
   kind: 'run-turn';

src/main/sidecar/sidecarProcess.ts

@@ -454,6 +454,7 @@ export class SidecarClient {
       case 'session-usage':
       case 'session-compaction':
       case 'pending-messages-modified':
+      case 'workflow-diagnostic':
       case 'assistant-usage':
       case 'assistant-intent':
       case 'reasoning-delta':

src/shared/contracts/sidecar.ts

@@ -384,6 +384,28 @@ export interface PendingMessagesModifiedEvent {
   agentName?: string;
 }
 
+export type WorkflowDiagnosticSeverity = 'warning' | 'error';
+export type WorkflowDiagnosticKind =
+  | 'workflow-warning'
+  | 'workflow-error'
+  | 'executor-failed'
+  | 'subworkflow-warning'
+  | 'subworkflow-error';
+
+export interface WorkflowDiagnosticEvent {
+  type: 'workflow-diagnostic';
+  requestId: string;
+  sessionId: string;
+  severity: WorkflowDiagnosticSeverity;
+  diagnosticKind: WorkflowDiagnosticKind;
+  message: string;
+  agentId?: string;
+  agentName?: string;
+  executorId?: string;
+  subworkflowId?: string;
+  exceptionType?: string;
+}
+
 export interface CopilotSessionInfo {
   copilotSessionId: string;
   managedByAryx: boolean;
@@ -563,6 +585,7 @@ export type SidecarEvent =
   | SessionUsageEvent
   | SessionCompactionEvent
   | PendingMessagesModifiedEvent
+  | WorkflowDiagnosticEvent
   | ApprovalRequestedEvent
   | UserInputRequestedEvent
   | McpOauthRequiredEvent

src/shared/domain/event.ts

@@ -1,7 +1,12 @@
 import type { SessionRunRecord } from '@shared/domain/runTimeline';
 import type { ChatMessageKind } from '@shared/domain/session';
 
-import type { QuotaSnapshot, ToolCallFileChangePreview } from '@shared/contracts/sidecar';
+import type {
+  QuotaSnapshot,
+  ToolCallFileChangePreview,
+  WorkflowDiagnosticKind,
+  WorkflowDiagnosticSeverity,
+} from '@shared/contracts/sidecar';
 
 export type SessionActivityType = 'thinking' | 'tool-calling' | 'handoff' | 'completed';
 
@@ -19,7 +24,8 @@ export type SessionEventKind =
   | 'session-usage'
   | 'session-compaction'
   | 'pending-messages-modified'
-  | 'assistant-usage';
+  | 'assistant-usage'
+  | 'workflow-diagnostic';
 
 export type SubagentEventKind = 'started' | 'completed' | 'failed' | 'selected' | 'deselected';
 
@@ -86,4 +92,12 @@ export interface SessionEventRecord {
   usageDuration?: number;
   usageTotalNanoAiu?: number;
   usageQuotaSnapshots?: Record<string, QuotaSnapshot>;
+
+  // Workflow diagnostic fields
+  diagnosticSeverity?: WorkflowDiagnosticSeverity;
+  diagnosticKind?: WorkflowDiagnosticKind;
+  diagnosticMessage?: string;
+  executorId?: string;
+  subworkflowId?: string;
+  exceptionType?: string;
 }