fix: reuse runtime processes across project sessions

Multiple projects could spawn duplicate heavyweight runtimes, while settings
changes and remote reconnection could cancel or strand native conversations.
Share compatible local OpenCode and DeepSeek Harness process owners and
Agent-owned ACP connections, retaining workspace routing, per-session modes,
model attribution, question ownership, targeted cancellation and idle cleanup.

Restore remote pending questions and terminal task projections across reconnect
and desktop restart, and preserve accepted ordinary requests during settings
replacement while cancelling expert-team parents with their replaced scheduler.
Extend regression coverage and Agent type checks. Record measured resource and
real-model validation results, including failures and limitations.

Also include the conversation media-generation design drafts (not an implemented
feature), documentation entry links and dedicated Linux test-directory guidance.
Desktop and Agent changes must be delivered together for shared process results.

Validation: typecheck and lint passed; staged content and documentation links
checked. Prior full regression and live-model evidence are recorded in progress
notes; no new full test suite or model calls were run for this commit.

Release note: 多项目会话现在复用兼容的 OpenCode 和 DeepSeek Harness 进程，减少重复启动并保持工作区、工具和取消隔离。修复远端问答在断线、重启及配置更新后的恢复与状态同步问题，Desktop 与 Agent 需配套更新。

src/main/agent/runtime-controller.test.ts

@@ -11,6 +11,39 @@ import {
   RuntimeReplacementCapacityError
 } from './runtime-controller'
 
+it('routes a shared request question to its original Runtime across replacement', async () => {
+  let release!: () => void
+  const gate = new Promise<void>(resolve => { release = resolve })
+  const previous: AgentRuntime = {
+    sharedProcess: true, requiresToolApproval: false, supportsToolExecution: true,
+    getStatus: vi.fn(), dispose: vi.fn(async () => undefined),
+    respondToQuestion: vi.fn(async () => undefined),
+    async *run(request) {
+      yield { type: 'question', requestId: request.requestId, questionId: 'question-old', questions: [] }
+      await gate
+      yield { type: 'done', requestId: request.requestId }
+    }
+  }
+  const next: AgentRuntime = { ...previous, respondToQuestion: vi.fn(async () => undefined) }
+  const controller = new AgentRuntimeController(previous, 1)
+  const stream = controller.run({
+    requestId: 'old-request', conversationId: 'old-conversation', prompt: 'test', workMode: 'execute'
+  }, new AbortController().signal)
+  try {
+    expect((await stream.next()).value?.type).toBe('question')
+    await controller.replace(next)
+    await controller.respondToQuestion('question-old', [])
+    expect(previous.respondToQuestion).toHaveBeenCalledWith('question-old', [])
+    expect(next.respondToQuestion).not.toHaveBeenCalled()
+    release()
+    expect((await stream.next()).value?.type).toBe('done')
+  } finally {
+    release()
+    await stream.return()
+    await controller.dispose()
+  }
+})
+
 class TestRuntime implements AgentRuntime {
   readonly dispose = vi.fn(async () => {})
   readonly started: Promise<void>
@@ -176,6 +209,26 @@ describe('AgentRuntimeController', () => {
     await controller.dispose()
   })
 
+  it('lets a shared local request finish while replacing its workspace facade', async () => {
+    const previous = Object.assign(new TestRuntime(true), { sharedProcess: true })
+    const controller = new AgentRuntimeController(previous, 1)
+    const stream = controller.run({
+      requestId: '00000000-0000-4000-8000-000000000071',
+      conversationId: 'shared-replacement', prompt: 'continue', workMode: 'ask'
+    }, new AbortController().signal)
+    const pending = stream.next()
+    await previous.started
+    await controller.replace(new TestRuntime())
+    expect(previous.dispose).not.toHaveBeenCalled()
+    previous.finish()
+    await expect(pending).resolves.toMatchObject({
+      done: false, value: { type: 'text' }
+    })
+    await stream.next()
+    expect(previous.dispose).toHaveBeenCalledOnce()
+    await controller.dispose()
+  })
+
   it('drains remote sessions without interrupting their active prompt', async () => {
     const previous = new DrainableTestRuntime()
     const next = new TestRuntime()