refactor: 拆分 3 个过大 ACP 文件为模块化子文件（每个 <500 行）

通过 4 阶段 workflow（分析 → 计划 → 重构 → 验证）将 3 个超大的 ACP
源文件拆分为 28 个模块化子文件，每个均严格小于 500 行，且完整保留
所有公共 API（barrel 模式重导出）。

变更概要：
- packages/acp-link/src/server.ts: 1800 → 20 行（barrel），新增 11 个子模块
  （server/types、payload-decode、permission-mode、runtime-state、dispatch、
  handlers-agent、handlers-session、acp-client、client-send、start-server、
  testing-internals）
- src/services/acp/agent.ts: 1297 → 33 行（barrel），新增 9 个子模块
  （agent/AcpAgent、sessionTypes、permissionMode、configOptions、promptQueue、
  internalAccessors、createSessionMethod、sessionLifecycle、promptFlow）
- src/services/acp/bridge.ts: 1516 → 29 行（barrel），新增 8 个子模块
  （bridge/types、paths、contentBlocks、toolInfo、toolResults、modelUsage、
  notifications、forwarding）

验证：
- bun run precheck 全通过（typecheck + lint + 5851 tests）
- ACP service tests: 176 pass / 0 fail
- ACP link tests: 47 pass / 0 fail
- 所有外部消费者（entry.ts、permissions.ts、__tests__/）的 import 路径不变
- 测试文件零修改

迁移计划详见 docs/acp-refactor-plan.md。

Co-Authored-By: glm-5.2 <zai-org@claude-code-best.win>

src/services/acp/agent/sessionLifecycle.ts

@@ -0,0 +1,280 @@
+/**
+ * Session-lifecycle methods for AcpAgent (excluding createSession, which
+ * lives in ./createSessionMethod.ts), attached to the prototype via
+ * Object.assign. The barrel (./index.ts) imports this module for its side
+ * effect so the prototype is populated before any instance is built.
+ *
+ * Methods attached here: getOrCreateSession, teardownSession,
+ * replaySessionHistory, applySessionMode, updateConfigOption.
+ */
+import { type UUID } from 'node:crypto'
+import { dirname } from 'node:path'
+import * as path from 'node:path'
+import type {
+  NewSessionRequest,
+  NewSessionResponse,
+} from '@agentclientprotocol/sdk'
+import type { Message } from '../../../types/message.js'
+import { deserializeMessages } from '../../../utils/conversationRecovery.js'
+import { getLastSessionLog } from '../../../utils/sessionStorage.js'
+import type { PermissionMode } from '../../../types/permissions.js'
+import { setOriginalCwd, switchSession } from '../../../bootstrap/state.js'
+import type { SessionId } from '../../../types/ids.js'
+import { replayHistoryMessages } from '../bridge.js'
+import { computeSessionFingerprint } from '../utils.js'
+import {
+  resolveSessionFilePath,
+  readSessionLite,
+  extractJsonStringField,
+} from '../../../utils/sessionStoragePortable.js'
+import { AcpAgent } from './AcpAgent.js'
+import type { AcpSession } from './sessionTypes.js'
+import { isPermissionMode } from './permissionMode.js'
+import {
+  getConnection,
+  readClientCapabilities,
+  syncSessionConfigState,
+} from './internalAccessors.js'
+
+// ── getOrCreateSession ───────────────────────────────────────────
+
+async function getOrCreateSession(
+  this: AcpAgent,
+  params: {
+    sessionId: string
+    cwd: string
+    mcpServers?: NewSessionRequest['mcpServers']
+    _meta?: NewSessionRequest['_meta']
+    // replay:true (default, session/load) streams the conversation history back
+    // to the client via session/update. replay:false (session/resume) only
+    // restores the in-process context — per session-setup.mdx the Agent MUST
+    // NOT replay history when resuming.
+    replay?: boolean
+  },
+): Promise<NewSessionResponse> {
+  const shouldReplay = params.replay !== false
+  const existingSession = this.sessions.get(params.sessionId)
+  if (existingSession) {
+    const fingerprint = computeSessionFingerprint({
+      cwd: params.cwd,
+      mcpServers: params.mcpServers as
+        | Array<{ name: string; [key: string]: unknown }>
+        | undefined,
+    })
+    if (fingerprint === existingSession.sessionFingerprint) {
+      const resolved = await resolveSessionFilePath(
+        params.sessionId,
+        params.cwd,
+      )
+      switchSession(
+        params.sessionId as SessionId,
+        resolved ? dirname(resolved.filePath) : null,
+      )
+      setOriginalCwd(params.cwd)
+
+      if (shouldReplay) {
+        await this.replaySessionHistory(params)
+      }
+
+      return {
+        sessionId: params.sessionId,
+        modes: existingSession.modes,
+        configOptions: existingSession.configOptions,
+      }
+    }
+
+    await this.teardownSession(params.sessionId)
+  }
+
+  // Locate the session file by sessionId across all project directories.
+  // params.cwd may not match the project directory where the session was
+  // originally created (e.g. client sends a subdirectory path), so we
+  // search by sessionId first and fall back to cwd-based lookup.
+  const resolved = await resolveSessionFilePath(params.sessionId, params.cwd)
+  const projectDir = resolved ? dirname(resolved.filePath) : null
+
+  // Per session-setup.mdx "Working Directory": the cwd MUST be the absolute
+  // path used for the session regardless of where the Agent was spawned.
+  // Reject cross-project loads where the persisted session's original cwd
+  // does not match the requested cwd, otherwise the client could load a
+  // session belonging to project B while passing project A's cwd.
+  if (resolved) {
+    const lite = await readSessionLite(resolved.filePath)
+    const originalCwd = lite && extractJsonStringField(lite.head, 'cwd')
+    if (originalCwd && path.resolve(originalCwd) !== path.resolve(params.cwd)) {
+      throw new Error(
+        `Session cwd mismatch: session belongs to ${originalCwd}, requested ${params.cwd}`,
+      )
+    }
+  }
+
+  switchSession(params.sessionId as SessionId, projectDir)
+  setOriginalCwd(params.cwd)
+
+  let initialMessages: Message[] | undefined
+  if (resolved) {
+    try {
+      const log = await getLastSessionLog(params.sessionId as UUID)
+      if (log && log.messages.length > 0) {
+        initialMessages = deserializeMessages(log.messages)
+      }
+    } catch (err) {
+      console.error('[ACP] Failed to load session history:', err)
+    }
+  }
+
+  const response = await this.createSession(
+    {
+      cwd: params.cwd,
+      mcpServers: params.mcpServers ?? [],
+      _meta: params._meta,
+    },
+    { sessionId: params.sessionId, initialMessages },
+  )
+
+  // Replay history to client if loaded. session/resume skips this block.
+  if (shouldReplay && initialMessages && initialMessages.length > 0) {
+    const session = this.sessions.get(params.sessionId)
+    if (session) {
+      await replayHistoryMessages(
+        params.sessionId,
+        initialMessages as unknown as Array<Record<string, unknown>>,
+        getConnection(this),
+        session.toolUseCache,
+        readClientCapabilities(this),
+        session.cwd,
+      )
+    }
+  }
+
+  return {
+    sessionId: response.sessionId,
+    modes: response.modes,
+    configOptions: response.configOptions,
+  }
+}
+
+// ── teardownSession ──────────────────────────────────────────────
+
+async function teardownSession(
+  this: AcpAgent,
+  sessionId: string,
+): Promise<void> {
+  const session = this.sessions.get(sessionId)
+  if (!session) return
+
+  await this.cancel({ sessionId })
+  this.sessions.delete(sessionId)
+}
+
+// ── replaySessionHistory ─────────────────────────────────────────
+
+/**
+ * Load session history from disk and replay it to the ACP client.
+ * Used when switching back to a session that is already in memory
+ * (the client needs the conversation replayed to display it).
+ */
+async function replaySessionHistory(
+  this: AcpAgent,
+  params: {
+    sessionId: string
+    cwd: string
+  },
+): Promise<void> {
+  try {
+    const log = await getLastSessionLog(params.sessionId as UUID)
+    if (!log || log.messages.length === 0) return
+    const messages = deserializeMessages(log.messages)
+    if (messages.length === 0) return
+
+    const session = this.sessions.get(params.sessionId)
+    if (!session) return
+
+    await replayHistoryMessages(
+      params.sessionId,
+      messages as unknown as Array<Record<string, unknown>>,
+      getConnection(this),
+      session.toolUseCache,
+      readClientCapabilities(this),
+      session.cwd,
+    )
+  } catch (err) {
+    console.error('[ACP] Failed to replay session history:', err)
+  }
+}
+
+// ── applySessionMode ─────────────────────────────────────────────
+
+function applySessionMode(
+  this: AcpAgent,
+  sessionId: string,
+  modeId: string,
+): void {
+  if (!isPermissionMode(modeId)) {
+    throw new Error(`Invalid mode: ${modeId}`)
+  }
+  const session = this.sessions.get(sessionId)
+  if (session) {
+    if (
+      modeId === 'bypassPermissions' &&
+      !session.appState.toolPermissionContext.isBypassPermissionsModeAvailable
+    ) {
+      throw new Error(`Mode not available: ${modeId}`)
+    }
+    const isAvailable = session.modes.availableModes.some(
+      mode => mode.id === modeId,
+    )
+    if (!isAvailable) {
+      throw new Error(`Mode not available: ${modeId}`)
+    }
+
+    session.modes = { ...session.modes, currentModeId: modeId }
+    // Sync mode to appState so the permission pipeline sees the correct mode
+    session.appState.toolPermissionContext = {
+      ...session.appState.toolPermissionContext,
+      mode: modeId as PermissionMode,
+    }
+  }
+}
+
+// ── updateConfigOption ───────────────────────────────────────────
+
+async function updateConfigOption(
+  this: AcpAgent,
+  sessionId: string,
+  configId: string,
+  value: string,
+): Promise<void> {
+  const session = this.sessions.get(sessionId)
+  if (!session) return
+
+  // Delegate to the shell's private syncSessionConfigState via a typed cast.
+  // The shell declares syncSessionConfigState as a private method; it is not
+  // part of the merged public interface, so we access it through the shared
+  // internal accessor to preserve exact original behavior.
+  syncSessionConfigState(this, session, configId, value)
+
+  session.configOptions = session.configOptions.map(o =>
+    o.id === configId && typeof o.currentValue === 'string'
+      ? { ...o, currentValue: value }
+      : o,
+  )
+
+  await getConnection(this).sessionUpdate({
+    sessionId,
+    update: {
+      sessionUpdate: 'config_option_update',
+      configOptions: session.configOptions,
+    },
+  })
+}
+
+// ── Prototype attachment ─────────────────────────────────────────
+
+Object.assign(AcpAgent.prototype, {
+  getOrCreateSession,
+  teardownSession,
+  replaySessionHistory,
+  applySessionMode,
+  updateConfigOption,
+})