feat: add workspace companion console MVP

web/workspace/src/lib/workspace-sidebar/CompanionNavSection.svelte

@@ -0,0 +1,20 @@
+<script lang="ts">
+  type Props = {
+    currentPath?: string;
+  };
+
+  let { currentPath = '/' }: Props = $props();
+
+  const active = $derived(currentPath === '/console');
+</script>
+
+<section class="sidebar-section" aria-labelledby="companion-console-heading">
+  <div class="section-heading-row">
+    <h2 id="companion-console-heading">Console</h2>
+    <span class="section-count">MVP</span>
+  </div>
+  <a class:active class="nav-item" href="/console" aria-current={active ? 'page' : undefined}>
+    <span class="item-title">Companion Console</span>
+    <span class="item-meta">status · transcript · send</span>
+  </a>
+</section>

web/workspace/src/lib/workspace-sidebar/WorkspaceSidebar.svelte

@@ -1,4 +1,5 @@
 <script lang="ts">
+  import CompanionNavSection from './CompanionNavSection.svelte';
   import ObjectivesNavSection from './ObjectivesNavSection.svelte';
   import RepositoriesNavSection from './RepositoriesNavSection.svelte';
   import WorkersNavSection from './WorkersNavSection.svelte';
@@ -41,6 +42,7 @@
   </header>
 
   <nav class="sidebar-sections" aria-label="Workspace sections">
+    <CompanionNavSection {currentPath} />
     <RepositoriesNavSection {workspace} {currentPath} />
     <ObjectivesNavSection {currentPath} />
     <WorkersNavSection />

web/workspace/src/lib/workspace-sidebar/types.ts

@@ -16,6 +16,7 @@ export type WorkspaceResponse = {
   extension_points: {
     event_stream: ExtensionPoint;
     host_worker_bridge: ExtensionPoint;
+    companion_console: ExtensionPoint;
   };
 };
 
@@ -209,3 +210,57 @@ export type ObjectiveListResponse = {
   invalid_records: InvalidProjectRecord[];
   record_authority: string;
 };
+
+export type CompanionState =
+  | 'ready'
+  | 'busy'
+  | 'error'
+  | 'timeout'
+  | 'cancelled'
+  | 'accepted'
+  | 'rejected';
+
+export type CompanionTransportSummary = {
+  kind: string;
+  completion: string;
+  limitation: string;
+};
+
+export type CompanionStatusResponse = {
+  state: CompanionState;
+  worker?: Worker | null;
+  transport: CompanionTransportSummary;
+  diagnostics: Diagnostic[];
+};
+
+export type CompanionTranscriptItem = {
+  sequence: number;
+  role: 'user' | 'assistant' | 'system' | string;
+  content: string;
+  created_at: string;
+  source: string;
+  status: string;
+};
+
+export type CompanionTranscriptProjection = {
+  state: CompanionState;
+  start: number;
+  limit: number;
+  total_items: number;
+  next_start?: number | null;
+  items: CompanionTranscriptItem[];
+  diagnostics: Diagnostic[];
+};
+
+export type CompanionMessageRequest = {
+  content: string;
+};
+
+export type CompanionMessageResponse = {
+  state: CompanionState;
+  worker?: Worker | null;
+  user_item?: CompanionTranscriptItem | null;
+  assistant_item?: CompanionTranscriptItem | null;
+  transcript: CompanionTranscriptProjection;
+  diagnostics: Diagnostic[];
+};