feat: generate and edit conversation images across runtimes

Add model-controlled image invocation and read-only runtime assignments. Route image tools through Main so accepted operations retain their originating conversation when chat runtimes change, with saved references, cancellation, and manual recovery.

Keep Node hashing outside browser-shared contracts to restore production builds. Validation includes the production build, typecheck, lint, focused regressions, real Host transport checks, and two successful real image requests. Full UI-driven runtime switching acceptance remains documented as pending.

Release note: 开启图片模型的会话调用后，聊天助手可调用图片生成与编辑工具，Runtime 分配自动管理。图片成果保存在原会话，可继续修改，并独立显示生成状态和取消入口。

src/agent-daemon/runtime-acp-backend.test.ts

@@ -1,4 +1,8 @@
 import { describe, expect, it, vi } from 'vitest'
+import { Client } from '@modelcontextprotocol/sdk/client/index.js'
+import { StreamableHTTPClientTransport } from '@modelcontextprotocol/sdk/client/streamableHttp.js'
+import { decodeRemoteImageToolMessage, encodeRemoteImageToolMessage, remoteImageToolCallSchema } from '../shared/remote-image-tool-contracts'
+import type { AgentFrame } from '../shared/agent-protocol'
 import { mkdtemp, rm } from 'node:fs/promises'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
@@ -309,7 +313,7 @@ function harness(input: {
       throw new Error('broker close failed')
     }
   })
-  const blobSink = vi.fn(async () => undefined)
+  const blobSink = vi.fn<(frame: AgentFrame) => Promise<void>>(async () => undefined)
   let bridgeDispatch: ModelBridgeBrokerDispatch | undefined
   const launchModelBridges: unknown[] = []
   const resolved = resolvedBundle()
@@ -451,6 +455,49 @@ function harness(input: {
 }
 
 describe('RuntimeAcpBackend', () => {
+  it('binds MCP image calls to authenticated blob framing and closes each prompt endpoint', async () => {
+    const fixture = harness({ workMode: 'execute' })
+    const client = new Client({ name: 'image-backend-test', version: '1' })
+    try {
+      await open(fixture)
+      const accepted = await invoke(fixture, 'runtime/preparePrompt', fixture.preparation({
+        imageTool: { channelId: 'image-channel', channelEpoch: '1', description: 'Image catalog' }
+      })) as { imageToolUrl: string }
+      await client.connect(new StreamableHTTPClientTransport(new URL(accepted.imageToolUrl)))
+      expect((await client.listTools()).tools.map(tool => tool.name)).toEqual(['generate_image'])
+      const result = client.callTool({ name: 'generate_image', arguments: { intent: 'create', prompt: 'Blue' } })
+      await vi.waitFor(() => expect(fixture.blobSink).toHaveBeenCalledOnce())
+      const frame = fixture.blobSink.mock.calls[0]![0]
+      expect(frame.header).toMatchObject({ channelId: 'image-channel', channelEpoch: '1', sequence: '1', direction: 'agent-to-main' })
+      expect(fixture.backend.authorizeBlobFrame(frame, fixture.context.controller)).toBe(true)
+      expect(fixture.backend.authorizeBlobFrame(frame, { ...fixture.context.controller, connectionId: 'foreign' })).toBe(false)
+      const call = remoteImageToolCallSchema.parse(decodeRemoteImageToolMessage(frame.payload))
+      const payload = encodeRemoteImageToolMessage({ callId: call.callId, error: 'Controlled test failure' })
+      const reply = { header: { ...frame.header, direction: 'main-to-agent' as const, payloadLength: payload.byteLength }, payload }
+      await expect(fixture.backend.onBlobFrame(reply, { ...fixture.context, channelId: 'image-channel', controller: { ...fixture.context.controller, connectionId: 'foreign' } })).rejects.toThrow('authority')
+      await fixture.backend.onBlobFrame(reply, { ...fixture.context, channelId: 'image-channel' })
+      expect(await result).toMatchObject({ isError: true })
+      await invoke(fixture, 'runtime/completePrompt', { bindingId: 'binding-1', operationId: 'request-1', requestId: 'request-1' })
+      await expect(fetch(accepted.imageToolUrl)).rejects.toThrow()
+      const next = await invoke(fixture, 'runtime/preparePrompt', fixture.preparation({
+        requestId: 'request-2', operationId: 'request-2', promptSequence: 1,
+        imageTool: { channelId: 'image-channel-2', channelEpoch: '2', description: 'Refreshed image catalog' }
+      })) as { imageToolUrl: string }
+      expect(next.imageToolUrl).not.toBe(accepted.imageToolUrl)
+    } finally { await client.close(); await fixture.backend.dispose() }
+  })
+
+  it('rejects image tool preparation in Ask before launching a process or bridge', async () => {
+    const fixture = harness()
+    try {
+      await open(fixture)
+      await expect(invoke(fixture, 'runtime/preparePrompt', fixture.preparation({
+        imageTool: { channelId: 'image-channel', channelEpoch: '1', description: 'Images' }
+      }))).rejects.toThrow('Execute')
+      expect(fixture.launches).toHaveLength(0)
+      expect(fixture.lifecycle).not.toContain('bridge-listen')
+    } finally { await fixture.backend.dispose() }
+  })
   it.each([false, true])('allows mode changes only on a shared Session (shared=%s)', async (shared) => {
     const fixture = harness({ agentOwned: true, shareOwnedProcesses: shared, workMode: 'execute' })
     try {