fix: stream session updates live

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

src/renderer/App.tsx

@@ -10,6 +10,7 @@ import {
   pruneSessionActivities,
   type SessionActivityMap,
 } from '@renderer/lib/sessionActivity';
+import { applySessionEventWorkspace } from '@renderer/lib/sessionWorkspace';
 import { WelcomePane } from '@renderer/components/WelcomePane';
 import { getElectronApi } from '@renderer/lib/electronApi';
 import type { PatternDefinition } from '@shared/domain/pattern';
@@ -70,6 +71,7 @@ export default function App() {
     });
 
     const offSessionEvent = api.onSessionEvent((event) => {
+      setWorkspace((current) => applySessionEventWorkspace(current, event));
       setSessionActivities((current) => applySessionEventActivity(current, event));
     });
 

src/renderer/lib/sessionWorkspace.ts

@@ -0,0 +1,155 @@
+import type { SessionEventRecord } from '@shared/domain/event';
+import type { ChatMessageRecord, SessionRecord } from '@shared/domain/session';
+import type { WorkspaceState } from '@shared/domain/workspace';
+
+export function applySessionEventWorkspace(
+  current: WorkspaceState | undefined,
+  event: SessionEventRecord,
+): WorkspaceState | undefined {
+  if (!current) {
+    return current;
+  }
+
+  const sessionIndex = current.sessions.findIndex((session) => session.id === event.sessionId);
+  if (sessionIndex < 0) {
+    return current;
+  }
+
+  const session = current.sessions[sessionIndex];
+  const nextSession = applySessionEvent(session, event);
+  if (nextSession === session) {
+    return current;
+  }
+
+  const nextSessions = current.sessions.slice();
+  nextSessions[sessionIndex] = nextSession;
+  return {
+    ...current,
+    sessions: nextSessions,
+  };
+}
+
+function applySessionEvent(session: SessionRecord, event: SessionEventRecord): SessionRecord {
+  switch (event.kind) {
+    case 'status':
+      return applyStatusEvent(session, event);
+    case 'error':
+      return applyErrorEvent(session, event);
+    case 'message-delta':
+      return applyMessageDeltaEvent(session, event);
+    case 'message-complete':
+      return applyMessageCompleteEvent(session, event);
+    default:
+      return session;
+  }
+}
+
+function applyStatusEvent(session: SessionRecord, event: SessionEventRecord): SessionRecord {
+  if (!event.status) {
+    return session;
+  }
+
+  if (session.status === event.status && (event.status === 'error' || !session.lastError)) {
+    return session;
+  }
+
+  return {
+    ...session,
+    status: event.status,
+    lastError: event.status === 'error' ? session.lastError : undefined,
+    updatedAt: event.occurredAt,
+  };
+}
+
+function applyErrorEvent(session: SessionRecord, event: SessionEventRecord): SessionRecord {
+  const error = event.error?.trim();
+  if (session.status === 'error' && session.lastError === error) {
+    return session;
+  }
+
+  return {
+    ...session,
+    status: 'error',
+    lastError: error,
+    updatedAt: event.occurredAt,
+  };
+}
+
+function applyMessageDeltaEvent(session: SessionRecord, event: SessionEventRecord): SessionRecord {
+  if (!event.messageId || event.contentDelta === undefined) {
+    return session;
+  }
+
+  const messageIndex = session.messages.findIndex((message) => message.id === event.messageId);
+  if (messageIndex >= 0) {
+    const existing = session.messages[messageIndex];
+    const nextMessage: ChatMessageRecord = {
+      ...existing,
+      authorName: event.authorName ?? existing.authorName,
+      content: `${existing.content}${event.contentDelta}`,
+      pending: true,
+    };
+
+    if (
+      nextMessage.authorName === existing.authorName
+      && nextMessage.content === existing.content
+      && existing.pending
+    ) {
+      return session;
+    }
+
+    const nextMessages = session.messages.slice();
+    nextMessages[messageIndex] = nextMessage;
+    return {
+      ...session,
+      messages: nextMessages,
+      updatedAt: event.occurredAt,
+    };
+  }
+
+  return {
+    ...session,
+    messages: [
+      ...session.messages,
+      {
+        id: event.messageId,
+        role: 'assistant',
+        authorName: event.authorName ?? 'assistant',
+        content: event.contentDelta,
+        createdAt: event.occurredAt,
+        pending: true,
+      },
+    ],
+    updatedAt: event.occurredAt,
+  };
+}
+
+function applyMessageCompleteEvent(session: SessionRecord, event: SessionEventRecord): SessionRecord {
+  if (!event.messageId) {
+    return session;
+  }
+
+  const messageIndex = session.messages.findIndex((message) => message.id === event.messageId);
+  if (messageIndex < 0) {
+    return session;
+  }
+
+  const existing = session.messages[messageIndex];
+  const nextMessage: ChatMessageRecord = {
+    ...existing,
+    authorName: event.authorName ?? existing.authorName,
+    pending: false,
+  };
+
+  if (nextMessage.authorName === existing.authorName && !existing.pending) {
+    return session;
+  }
+
+  const nextMessages = session.messages.slice();
+  nextMessages[messageIndex] = nextMessage;
+  return {
+    ...session,
+    messages: nextMessages,
+    updatedAt: event.occurredAt,
+  };
+}