feat: bootstrap secure cross-platform assistant

Establish the Electron foundation and pluggable agent runtime so desktop workflows can evolve safely across supported platforms.

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

src/shared/contracts.ts

@@ -0,0 +1,69 @@
+import { z } from 'zod'
+
+export const agentRequestSchema = z.object({
+  requestId: z.string().uuid(),
+  conversationId: z.string().min(1).max(128),
+  prompt: z.string().trim().min(1).max(100_000),
+  workspace: z.string().max(2_048).optional()
+})
+
+export type AgentRequest = z.infer<typeof agentRequestSchema>
+
+export type AgentRuntimeStatus = {
+  id: 'demo' | 'bigtoken' | 'opencode'
+  label: string
+  available: boolean
+  detail: string
+}
+
+export type AgentEvent =
+  | {
+      requestId: string
+      type: 'status'
+      message: string
+    }
+  | {
+      requestId: string
+      type: 'text'
+      delta: string
+    }
+  | {
+      requestId: string
+      type: 'tool'
+      name: string
+      state: 'pending' | 'running' | 'completed' | 'failed'
+      summary: string
+    }
+  | {
+      requestId: string
+      type: 'done'
+      sessionId?: string
+    }
+  | {
+      requestId: string
+      type: 'error'
+      message: string
+    }
+
+export type AppInfo = {
+  name: string
+  version: string
+  platform: string
+  arch: string
+  shortcut: string
+}
+
+export type DesktopApi = {
+  app: {
+    getInfo: () => Promise<AppInfo>
+    show: () => Promise<void>
+    hide: () => Promise<void>
+    onNewConversation: (listener: () => void) => () => void
+  }
+  agent: {
+    getStatus: () => Promise<AgentRuntimeStatus>
+    run: (request: AgentRequest) => Promise<void>
+    cancel: (requestId: string) => Promise<void>
+    onEvent: (listener: (event: AgentEvent) => void) => () => void
+  }
+}