feat: add thinking protocol events

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

src/shared/domain/event.ts

@@ -1,4 +1,5 @@
 import type { SessionRunRecord } from '@shared/domain/runTimeline';
+import type { ChatMessageKind } from '@shared/domain/session';
 
 import type { QuotaSnapshot, ToolCallFileChangePreview } from '@shared/contracts/sidecar';
 
@@ -8,6 +9,7 @@ export type SessionEventKind =
   | 'status'
   | 'message-delta'
   | 'message-complete'
+  | 'message-reclassified'
   | 'agent-activity'
   | 'run-updated'
   | 'error'
@@ -27,6 +29,7 @@ export interface SessionEventRecord {
   occurredAt: string;
   status?: 'idle' | 'running' | 'error';
   messageId?: string;
+  messageKind?: ChatMessageKind;
   authorName?: string;
   contentDelta?: string;
   content?: string;

src/shared/domain/session.ts

@@ -18,6 +18,7 @@ import type { ChatMessageAttachment } from '@shared/domain/attachment';
 import type { InteractionMode } from '@shared/contracts/sidecar';
 
 export type ChatRole = 'system' | 'user' | 'assistant';
+export type ChatMessageKind = 'response' | 'thinking';
 export type SessionStatus = 'idle' | 'running' | 'error';
 export type SessionTitleSource = 'auto' | 'manual';
 export type SessionBranchOriginAction = 'branch' | 'regenerate' | 'edit-and-resend';
@@ -33,6 +34,7 @@ export interface ChatMessageRecord {
   authorName: string;
   content: string;
   createdAt: string;
+  messageKind?: ChatMessageKind;
   isPinned?: boolean;
   pending?: boolean;
   attachments?: ChatMessageAttachment[];