Merge branch 'master' into worktree/command-row-copy

packages/client/runtime/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/client/runtime/README.md
-README.md: 766d8516225cd46cb1a3a80c832d1cf55e816140
-README.zh.md: 9b514afca91f604b3e895187de3b5532bf22a692
+README.md: b85deeec92fd4da1f342b5536757692f594853a5
+README.zh.md: 2dbb66c56ad5687fb299fe030d0abfe451004a62

packages/client/runtime/README.md

@@ -28,6 +28,10 @@ SlotsService gives the renderer separate bare observables for `useSessions` and
 
 `SessionManager` retains the latest validated `session/title` control snapshot independently of list and session-instance arrival. Newer event seqs replace older snapshots, title timestamps contribute to list recency, and a subscription baseline discards any retained title beyond its `lastSeq` before the optional folded title arrives. Explicit session removal also clears the retained title. The client-facing `SessionSummary.title` is therefore only the actual durable title; `displayTitle` is always present and falls back through the cwd basename and session id. A cold persisted session keeps that fallback until opening or resuming it causes the host to fold and project its log-backed title. `ISession.rename` settles the `title` projection cell directly from the unary response's `{title, seq}` under the same higher-seq-wins rule — the list row and every `useProjection('title')` reader update ahead of the push frame, whose later replay of the same seq is a no-op.
 
+## Session forking
+
+`ISessions.fork({sessionId, atSeq?, increaseTitle?})` resolves only after the child summary is locally addressable, carrying source lineage and cwd with `blank: false`; callers choose whether to open it. With `increaseTitle: true`, the client renames the child from the source session's persisted title: a trailing `(N)` or `（N）` is incremented without changing bracket style, while any other title gets ` (1)` appended; the rename is skipped when the source has no persisted title, and a rename failure rejects the promise but leaves the created child in place. This option is not sent in the Host fork request. A `workspace-attach-failed` response still identifies a child already published by the Host, so `SessionManager` reconciles that partial success before `SessionForkError` reaches the caller instead of making a retry create a duplicate child.
+
 ## Session model selection
 
 Each resident `Session` owns a `modelSelection` snapshot containing the current provider/model target, provider-grouped directory, provider-local failures, and the `idle`/`loading`/`ready`/`selecting`/`error` state. History establishes or refreshes the current target, opening a selector refreshes the directory, and selection failures preserve the last target and usable groups. Directory and selection operations share a monotonically increasing generation so an older response cannot overwrite a newer selection. A reconnect rebuild restores the target reported by the Host without replacing unchanged selection substructure.

packages/client/runtime/README.zh.md

@@ -28,6 +28,10 @@ SlotsService 分别为 renderer 提供 `useSessions` 与 `useWorkspaces` 的裸
 
 `SessionManager` 独立于列表和 Session 实例到达情况，保留最近一次通过验证的 `session/title` 控制快照。seq 更高的事件会替换旧快照，标题时间戳计入列表新近程度；订阅基线会先丢弃 seq 超过其 `lastSeq` 的任何已保留标题，再接收可选的折叠标题。显式移除 Session 也会清除已保留标题。因此，面向客户端的 `SessionSummary.title` 只包含实际的持久化标题；`displayTitle` 始终存在，并依次回退到 cwd basename 和 Session id。冷态持久化会话会保持该回退值，直到打开或恢复会话，促使主机折叠并投影由日志支撑的标题。`ISession.rename` 用 unary 响应中的 `{title, seq}` 直接结算 `title` 投影格，遵循同一 seq 高者胜规则——列表行和所有 `useProjection('title')` 读者在推送帧到达前即更新；推送帧随后重放同一 seq 时为无操作。
 
+## 会话 fork
+
+`ISessions.fork({sessionId, atSeq?, increaseTitle?})` 只在子会话摘要已能在本地寻址后才完成；该摘要携带源会话的谱系和 cwd，且 `blank: false`，由调用方决定是否打开。`increaseTitle: true` 会在 client 端把源会话的持久化标题改名到子会话：尾部 `(N)` 或 `（N）` 递增并保留括号样式，其余标题追加 ` (1)`；源会话没有持久化标题时跳过改名，改名失败时拒绝 promise 但保留已创建的子会话。该选项不会进入 Host fork 请求。即使响应为 `workspace-attach-failed`，其中仍会标识 Host 已发布的子会话，因此 `SessionManager` 会先将这一部分成功对账，再让 `SessionForkError` 到达调用方，避免重试创建重复的子会话。
+
 ## 会话模型选择
 
 每个常驻 `Session` 都拥有一个 `modelSelection` 快照，其中包含当前提供方/模型目标、按提供方分组的目录、逐提供方失败记录，以及 `idle`／`loading`／`ready`／`selecting`／`error` 状态。历史记录会建立或刷新当前目标，打开选择器会刷新目录；选择失败会保留上一个目标和可用分组。目录与选择操作共用单调递增的代次，因此较旧响应无法覆盖较新的选择。重连重建会恢复 Host 报告的目标，同时不替换未变化的选择子结构。

packages/client/runtime/src/client/contract/sessions.ts

@@ -29,6 +29,17 @@ export interface ISessions {
   open(id: SessionId): void
   /** Clear the current selection into the no-session view state. */
   clear(): void
+  /**
+   * Fork a session from a completed-turn prefix of the source; on resolution
+   * the child is in the list store and `open()` can target it.
+   * @param opts - source session id, the optional event seq anchoring the
+   *   cut (the boundary is the first turn/end at or after it; an in-log
+   *   anchor in an open turn is unavailable rather than clipped backward),
+   *   and whether to increment an inherited durable title before resolving.
+   * @returns the child session id.
+   * @throws when the fork fails, or when a requested child-title rename fails after creation.
+   */
+  fork(opts: { sessionId: SessionId; atSeq?: number; increaseTitle?: boolean }): Promise<SessionId>
   /**
    * Register a per-session standard-props provider (hooks become `use<Name>`
    * selector hooks on the render side; props spread verbatim).

packages/client/runtime/src/client/sessions/manager.ts

@@ -289,6 +289,40 @@ export class SessionManager {
     }
   }
 
+  /**
+   * Contract session.fork; on success merge the child into summaries
+   * immediately (same synchronous-addressability guarantee as create). The
+   * child carries the source's history, so it is never blank; lineage rides
+   * parentSessionId so the list nests it under its source. A child published
+   * before Workspace attachment fails is also reconciled into the list.
+   * @param opts - source session and the optional seq anchoring the cut.
+   * @returns the fork result (the child session id).
+   */
+  async fork(
+    opts: { sessionId: SessionId; atSeq?: number },
+  ): Promise<RpcResult<{ sessionId: SessionId }>> {
+    try {
+      const source = this.summaries.find(s => s.sessionId === opts.sessionId)
+      const { result } = await this.api.sessions.fork({
+        sessionId: opts.sessionId,
+        ...opts.atSeq === undefined ? {} : { atSeq: opts.atSeq },
+      })
+      const childId = result.ok
+        ? result.value.sessionId
+        : workspaceAttachSessionId(result.error)
+      if (childId !== undefined) {
+        this.recordMutation({ kind: 'upsert', summary: {
+          sessionId: childId, updatedAt: Date.now(), running: false, blank: false,
+          parentSessionId: opts.sessionId,
+          ...(source?.cwd !== undefined ? { cwd: source.cwd } : {}),
+        } })
+      }
+      return result
+    } catch (error) {
+      return transportError(error)
+    }
+  }
+
   /**
    * Insert-or-enrich a locally synthesized summary: a new id prepends; an
    * existing entry only gains fields it lacks (the session-added frame and the

packages/client/runtime/src/client/sessions/service.ts

@@ -81,6 +81,22 @@ export class SessionCreateError extends Error {
   }
 }
 
+/** Structured session-fork failure. */
+export class SessionForkError extends Error {
+  override readonly name = 'SessionForkError'
+
+  /**
+   * @param rpcError - Host business or folded transport error.
+   * @param sourceSessionId - the session the fork was cut from.
+   */
+  constructor(
+    readonly rpcError: RpcError,
+    readonly sourceSessionId: SessionId,
+  ) {
+    super(`session fork failed: ${rpcError.code}: ${rpcError.message}`)
+  }
+}
+
 /** Session assembly handle for SessionProvider/inject factories (identity-stable per session). */
 export interface SessionBinding {
   readonly sessionId: SessionId
@@ -121,6 +137,24 @@ function displayTitleOf(title: string | undefined, cwd: string | undefined, id:
   return id
 }
 
+/**
+ * Increment a trailing fork number while preserving its half-width or
+ * full-width parentheses; an unnumbered title starts with ` (1)`.
+ * @param title - source session's durable title.
+ * @returns the title assigned to the fork child.
+ */
+function increasedForkTitle(title: string): string {
+  const ascii = /^(.*?)\((\d+)\)$/u.exec(title)
+  if (ascii?.[1] !== undefined && ascii[2] !== undefined) {
+    return `${ascii[1]}(${BigInt(ascii[2]) + 1n})`
+  }
+  const fullWidth = /^(.*?)（(\d+)）$/u.exec(title)
+  if (fullWidth?.[1] !== undefined && fullWidth[2] !== undefined) {
+    return `${fullWidth[1]}（${BigInt(fullWidth[2]) + 1n}）`
+  }
+  return `${title} (1)`
+}
+
 interface ScopeRecord {
   fiber: Fiber
   ctx: Context
@@ -317,6 +351,42 @@ export class SessionsService implements ISessions {
     return result.value.sessionId
   }
 
+  /**
+   * Fork a session from a completed-turn prefix of the source (same
+   * synchronous-addressability guarantee as {@link SessionsService.create}:
+   * on resolution the child is in the list store and open() can target it).
+   * @param opts - source session id, the optional event seq anchoring the
+   *   cut (the boundary is the first turn/end at or after it; an in-log
+   *   anchor in an open turn is unavailable rather than clipped backward),
+   *   and whether to increment an inherited durable title before resolving.
+   * @returns the child session id.
+   * @throws {SessionForkError} with the source id.
+   * @throws {Error} when a requested child-title rename fails after creation.
+   */
+  async fork(opts: {
+    sessionId: SessionId
+    atSeq?: number
+    increaseTitle?: boolean
+  }): Promise<SessionId> {
+    const sourceTitle = opts.increaseTitle
+      ? this.list.getSnapshot().byId[opts.sessionId]?.title
+      : undefined
+    const result = await this.manager.fork({
+      sessionId: opts.sessionId,
+      ...(opts.atSeq === undefined ? {} : { atSeq: opts.atSeq }),
+    })
+    if (!result.ok) throw new SessionForkError(result.error, opts.sessionId)
+    this.projectList()
+    const childId = result.value.sessionId
+    if (sourceTitle !== undefined) {
+      const child = this.binding(childId)?.session
+      if (child === undefined) throw new Error(`fork child "${childId}" is not locally addressable`)
+      const renamed = await child.rename(increasedForkTitle(sourceTitle))
+      if (!renamed.ok) throw new Error(`fork child rename failed: ${renamed.error.code}: ${renamed.error.message}`)
+    }
+    return childId
+  }
+
   /**
    * Resolve an Agent-scoped context view (use-and-discard).
    * @param id - session id (the agent identity — 1:1 same axis).

packages/client/runtime/tests/fake-api.ts

@@ -64,6 +64,7 @@ export class FakeApiClient implements IApiClient {
   onCreate: (payload: unknown) => Promise<RpcResponse<{ sessionId: SessionId }>> = () => Promise.resolve(ok({ sessionId: 'fk-new' as SessionId }))
   readonly defaultModel: ModelTarget = { provider: 'deepseek', model: 'deepseek-v4-flash' }
   onRename: (payload: unknown) => Promise<RpcResponse<{ title: string; seq: number }>> = () => Promise.resolve(ok({ title: 'fk-renamed', seq: 0 }))
+  onFork: (payload: unknown) => Promise<RpcResponse<{ sessionId: SessionId }>> = () => Promise.resolve(ok({ sessionId: 'fk-fork' as SessionId }))
   onHistory: (payload: { sessionId: SessionId; beforeSeq?: number; maxMessages?: number })
   => Promise<RpcResponse<{ events: never[]; hasMore: boolean }>> =
     () => Promise.resolve(ok({ events: [], hasMore: false }))
@@ -118,6 +119,7 @@ export class FakeApiClient implements IApiClient {
     selectModel: (payload: { provider: string; model: string }) =>
       this.record('session.selectModel', payload, this.onSelectModel(payload)),
     rename: (payload: unknown) => this.record('session.rename', payload, this.onRename(payload)),
+    fork: (payload: unknown) => this.record('session.fork', payload, this.onFork(payload)),
     prompt: (payload: unknown) => this.record('session.prompt', payload, this.onPrompt(payload)),
     updateQueue: (payload: unknown) => this.record('session.updateQueue', payload, this.onUpdateQueue(payload)),
     cancel: (payload: unknown) => this.record('session.cancel', payload, this.onCancel(payload)),

packages/client/runtime/tests/manager.spec.ts

@@ -277,6 +277,23 @@ describe('remaining branches', () => {
     expect(manager.getListSnapshot().items[0]).not.toHaveProperty('cwd')
   })
 
+  it('reconciles a fork child published before workspace attachment fails', async () => {
+    const api = new FakeApiClient()
+    api.onFork = () => Promise.resolve(err({
+      code: 'workspace-attach-failed',
+      message: 'forked but unattached',
+      details: { sessionId: S2, workspaceId: 'w1' },
+    } as never))
+    const manager = new SessionManager(api)
+    const result = await manager.fork({ sessionId: S1 })
+    expect(result).toMatchObject({ ok: false, error: { code: 'workspace-attach-failed' } })
+    expect(manager.getListSnapshot().items).toEqual([expect.objectContaining({
+      sessionId: S2,
+      parentSessionId: S1,
+      blank: false,
+    })])
+  })
+
   it('reconciles a preallocated id after an ordinary transport failure', async () => {
     const api = new FakeApiClient()
     api.onCreate = () => Promise.reject(new Error('response lost'))

packages/client/runtime/tests/sessions-service.spec.ts

@@ -10,7 +10,7 @@ import { Context } from 'cordis'
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import type { SessionId } from '@deepseek-ai/dsh-client-connection/client'
 import { SessionCreateError, SessionsService, scopeOf } from '../src/client/sessions/service.ts'
-import { FakeApiClient, deferred, ok } from './fake-api.ts'
+import { FakeApiClient, deferred, err, ok } from './fake-api.ts'
 
 const sid = (s: string): SessionId => s as SessionId
 
@@ -399,6 +399,69 @@ describe('create', () => {
   })
 })
 
+describe('fork', () => {
+  it.each([
+    ['Roadmap', 'Roadmap (1)'],
+    ['Roadmap (1)', 'Roadmap (2)'],
+    ['计划（1）', '计划（2）'],
+    ['计划 （9）', '计划 （10）'],
+  ])('increments the durable title %j after the child is published', async (sourceTitle, childTitle) => {
+    const b = bench()
+    b.svc.handleMuxEnvelope({
+      rpcId: 'source-title' as never,
+      payload: { type: 'session/projection', sessionId: sid('source'), key: 'title', value: sourceTitle, seq: 2 } as never,
+    })
+    await feedList(b, [{ id: 'source', cwd: '/work' }])
+    b.api.onFork = () => Promise.resolve(ok({ sessionId: sid('child') }))
+    b.api.onRename = (payload) => {
+      const { title } = payload as { title: string }
+      return Promise.resolve(ok({ title, seq: 3 }))
+    }
+
+    await expect(b.svc.fork({
+      sessionId: sid('source'), atSeq: 7, increaseTitle: true,
+    })).resolves.toBe('child')
+
+    expect(b.api.callsOf('session.fork')).toEqual([{ sessionId: 'source', atSeq: 7 }])
+    expect(b.api.callsOf('session.rename')).toEqual([{ sessionId: 'child', title: childTitle }])
+    await Promise.resolve()
+    expect(b.svc.list.getSnapshot().byId[sid('child')]).toMatchObject({
+      title: childTitle,
+      displayTitle: childTitle,
+      parentId: 'source',
+    })
+  })
+
+  it('does not rename without the title policy or a durable source title', async () => {
+    const b = bench()
+    await feedList(b, [{ id: 'source', cwd: '/work' }])
+    b.api.onFork = () => Promise.resolve(ok({ sessionId: sid('child') }))
+    await expect(b.svc.fork({ sessionId: sid('source'), increaseTitle: true })).resolves.toBe('child')
+    expect(b.api.callsOf('session.rename')).toEqual([])
+
+    b.api.onFork = () => Promise.resolve(ok({ sessionId: sid('child-2') }))
+    await expect(b.svc.fork({ sessionId: sid('source') })).resolves.toBe('child-2')
+    expect(b.api.callsOf('session.rename')).toEqual([])
+  })
+
+  it('rejects when child rename fails while keeping the published child addressable', async () => {
+    const b = bench()
+    b.svc.handleMuxEnvelope({
+      rpcId: 'source-title' as never,
+      payload: { type: 'session/projection', sessionId: sid('source'), key: 'title', value: 'Roadmap', seq: 2 } as never,
+    })
+    await feedList(b, [{ id: 'source' }])
+    b.api.onFork = () => Promise.resolve(ok({ sessionId: sid('child') }))
+    b.api.onRename = () => Promise.resolve(err({
+      code: 'title-invalid', message: 'rejected', details: { sessionId: sid('child') },
+    }))
+
+    await expect(b.svc.fork({ sessionId: sid('source'), increaseTitle: true }))
+      .rejects.toThrow('fork child rename failed: title-invalid: rejected')
+    expect(b.svc.binding(sid('child'))).toBeDefined()
+  })
+})
+
 describe('scope lifecycle rides the list mirror (entity parity: no client-side pre-birth)', () => {
   it('a session-added frame births the row (blank) and makes the scope resolvable; removal prunes it', async () => {
     const b = bench()