Merge remote-tracking branch 'github/master' into xtr/trajectory-inspection-ui

packages/client/README.i18n.yaml

@@ -0,0 +1,6 @@
+# Bilingual-pair consistency record (docs/i18n/README.md): the git blob hash of each
+# 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/README.md
+README.md: b111d67fa49e06227e324a33bd53417ad28c3a5b
+README.zh.md: b498008eb82f6ab357718f2af761f38e51140ef8

packages/client/README.md

@@ -0,0 +1,34 @@
+# client/ — web-GUI browser half
+
+English | [中文](README.zh.md)
+
+The browser side of the dsh web GUI: shell kernel, module system, wire consumer, React-free object services, the slot system, and the `ui-*` feature-plugin roster. Authoring rules live in [AGENTS.md](AGENTS.md); the host half is [`host/`](../host/README.md). All **product** packages, named `@deepseek-ai/dsh-client-<name>`.
+
+| Package | Role | ctx key / slot |
+|---|---|---|
+| `web/` | Shell kernel: `AppWebEntry` runs the two-stage boot over the host-pushed entry graph | (boots the tree) |
+| `modules/` | Client module system: browser peer of Node's ESM loader as a lazy CJS table under the vendored cordis Loader | (module face) |
+| `web-react/` | Shell-side React glue: `createSlotRenderer` + `SessionProvider` render seats | (renderer install) |
+| `connection/` | Wire consumer both ends: browser `ctx.connection` (shared api client + stream loop) and the node half mounting the `/api` route with its browser-trust fence | `ctx.connection` |
+| `runtime/` | Client cordis boot and React-free object services: slots, Sessions, Workspaces, per-session bindings | `ctx.slots` `ctx.sessions` `ctx.workspaces` |
+| `hmr/` | Dev-only hot reload for fetch-arrival client plugins (`--dev` graphs) | (dev entry) |
+| `locale/` | Browser locale preference (`zh`/`en`) plus the ns×locale dictionary registry | `ctx.locale` |
+| `ui-slots/` | Slot registry pure core: SlotMap merging, single `register` API, the four-share props family | (types + core) |
+| `ui-theme/` | Theme preference over the `--dsw-*` token stylesheets (`light`/`dark`/`system`) | `ctx.theme` |
+| `ui-primitives/` | Pure React atoms: icons, Button/Pill/Menu/Modal/Input, markdown family | (component library) |
+| `ui-layout/` | Shell three-column AppFrame; declares `sidebar` / `conversation` / `details` / `conversation.empty` | `ctx.layout` |
+| `ui-sidebar/` | Sidebar shell: Workspace/session rail, search, collapse; declares `sidebar.workspaces` | (slot host) |
+| `ui-workspace/` | Shared Workspace picker: browser region + hero picker over the same creation flow | (fills `sidebar.workspaces`, `conversation.hero.workspace`) |
+| `ui-conversation/` | Conversation domain: skeleton, chat view, input dock, per-tool row slots | (slot host) |
+| `ui-trajectory/` | Trajectory/Waterfall view tabs; the minimal pure-consumer plugin exemplar | (fills `conversation.view`) |
+| `ui-command/` | Command surface: session-keyed directory cache, `/` source, three-kind dispatch | `ctx.command` |
+| `ui-slash/` | Input trigger pipeline: `/` and `@` detection, grouped candidate menu, source roster | `ctx.slash` |
+| `ui-skill/` | `/`-trigger skill reference source over the `skill.list` RPC | (registers into `ctx.slash`) |
+| `ui-subagent/` | `@`-trigger subagent reference source over the sessions snapshot | (registers into `ctx.slash`) |
+| `ui-model/` | Model selection: `/model` popupSelect + the composer model seat over `ModelService` | `ctx.models` |
+| `ui-question/` | Web `ask_user_question`: host half mounts the tool, browser half fills the composer seat | (fills `conversation.composer`) |
+| `ui-settings/` | Settings shell: trigger chrome + modal panel; declares the `settings.*` slots | (slot host) |
+| `ui-settings-general/` | Settings ownerless copy: chrome content + General section skeleton | (fills `settings.*`) |
+| `ui-models/` | Models settings nav entry (content column lands in a later phase) | (fills `settings.section`) |
+
+Feature UI composes only through the slot system (`ctx.slots.register`) — the [slot system standard](../../.agents/notes/implemented/architecture/2026-07-22-slot-type-chain-implementation.md) is the definitive model; the [web client architecture note](../../.agents/notes/implemented/architecture/2026-07-19-gui-web-client-architecture.md) owns the loading chain and object layer.

packages/client/README.zh.md

@@ -0,0 +1,34 @@
+# client/ — web GUI 浏览器半侧
+
+[English](README.md) | 中文
+
+dsh web GUI 的浏览器侧：shell 内核、模块系统、协议消费层、无 React 依赖的对象服务、slot 系统，以及 `ui-*` 特性插件阵列。编写规则见 [AGENTS.md](AGENTS.md)；宿主半侧是 [`host/`](../host/README.md)。全部为**产品**包，命名为 `@deepseek-ai/dsh-client-<name>`。
+
+| 包 | 角色 | ctx 键／slot |
+|---|---|---|
+| `web/` | shell 内核：`AppWebEntry` 基于宿主推送的条目图运行两阶段启动 | （启动整棵树） |
+| `modules/` | 客户端模块系统：Node ESM 加载器的浏览器对等物，是 vendored cordis Loader 之下的惰性 CJS 表 | （模块面） |
+| `web-react/` | shell 侧 React 胶水：`createSlotRenderer` + `SessionProvider` 渲染座位 | （渲染器安装） |
+| `connection/` | 协议两端的消费者：浏览器侧 `ctx.connection`（共享 api 客户端 + 流循环），node 半侧挂载带浏览器信任栅栏的 `/api` 路由 | `ctx.connection` |
+| `runtime/` | 客户端 cordis 启动与无 React 对象服务：slots、Session、Workspace、逐会话绑定 | `ctx.slots` `ctx.sessions` `ctx.workspaces` |
+| `hmr/` | 仅开发用的 fetch 到达型客户端插件热重载（`--dev` 图） | （开发条目） |
+| `locale/` | 浏览器语言偏好（`zh`／`en`）与 ns×locale 词典注册表 | `ctx.locale` |
+| `ui-slots/` | slot 注册表纯核心：SlotMap 合并、单一 `register` API、四份额 props 族 | （类型 + 核心） |
+| `ui-theme/` | 基于 `--dsw-*` token 样式表的主题偏好（`light`／`dark`／`system`） | `ctx.theme` |
+| `ui-primitives/` | 纯 React 原子：图标、Button/Pill/Menu/Modal/Input、markdown 族 | （组件库） |
+| `ui-layout/` | shell 三栏 AppFrame；声明 `sidebar`／`conversation`／`details`／`conversation.empty` | `ctx.layout` |
+| `ui-sidebar/` | 侧栏 shell：Workspace/会话栏、搜索、折叠；声明 `sidebar.workspaces` | （slot 宿主） |
+| `ui-workspace/` | 共享 Workspace 选择器：浏览区域 + hero 选择器共用同一创建流程 | （填充 `sidebar.workspaces`、`conversation.hero.workspace`） |
+| `ui-conversation/` | 会话域：骨架、聊天视图、输入坞、逐工具行 slot | （slot 宿主） |
+| `ui-trajectory/` | Trajectory／Waterfall 视图标签；最小纯消费者插件范例 | （填充 `conversation.view`） |
+| `ui-command/` | 命令面：按会话键控的目录缓存、`/` 源、三类分发 | `ctx.command` |
+| `ui-slash/` | 输入触发流水线：光标下的 `/` 与 `@` 检测、分组候选菜单、源名册 | `ctx.slash` |
+| `ui-skill/` | 基于 `skill.list` RPC 的 `/` 触发技能引用源 | （注册进 `ctx.slash`） |
+| `ui-subagent/` | 基于会话快照的 `@` 触发子代理引用源 | （注册进 `ctx.slash`） |
+| `ui-model/` | 模型选择：`/model` popupSelect + 输入坞模型座位，均由 `ModelService` 驱动 | `ctx.models` |
+| `ui-question/` | Web `ask_user_question`：宿主半侧挂载工具，浏览器半侧填充输入坞座位 | （填充 `conversation.composer`） |
+| `ui-settings/` | 设置 shell：触发 chrome + 模态面板；声明 `settings.*` slot | （slot 宿主） |
+| `ui-settings-general/` | 设置的无主文案：chrome 内容 + General 分区骨架 | （填充 `settings.*`） |
+| `ui-models/` | 模型设置导航项（内容列留待后续阶段） | （填充 `settings.section`） |
+
+特性 UI 只通过 slot 系统组合（`ctx.slots.register`）——[slot 系统标准](../../.agents/notes/implemented/architecture/2026-07-22-slot-type-chain-implementation.md)是权威模型；[web 客户端架构 Note](../../.agents/notes/implemented/architecture/2026-07-19-gui-web-client-architecture.md) 拥有加载链与对象层。

packages/client/connection/README.i18n.yaml

@@ -1,6 +1,6 @@
 # Bilingual-pair consistency record (docs/i18n/README.md): the git blob hash of each
 # 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
-README.md: 80228a180faba0c556ff720e999b29b5bb1635b6
-README.zh.md: f4b857886bfafa891ceb1bd6b79b27e1fb725819
+#   pnpm run verify-translation-pairing --write packages/client/connection/README.md
+README.md: 173a9b9998e17d201b2d31d73ea74a94b319dae6
+README.zh.md: ca5da643db443956c25399f07c8b460900942ad4

packages/client/connection/README.md

@@ -4,6 +4,10 @@ English | [中文](README.zh.md)
 
 Wire consumer layer: the client plugin's apply mounts `ctx.connection` (shared api client + single-consumer stream-loop starter); the export face carries the wire contract types, the `AbstractApiClient` seam, and the loop's sink/config types. The platform subclasses (WebApiClient/FixtureApiClient), the ConnectionController loop, and the fixture data source are package-internal — apply selects and drives them; tests reach them via src. Contract: api-contracts v3 §3.
 
+## /api browser-trust fence
+
+The node half guards every request under `/api` before bridging (`src/api-request-trust.ts`). Every request — browser-marked or not — must present a `Host` that is a loopback authority or matches a `trustedHosts` entry: exact on `host:port` entries, any port on port-less entries, both sides compared through WHATWG normalization (DNS-rebinding defense). There is deliberately no shortcut for requests without browser markers: over plain HTTP a browser attaches neither `Origin` nor Fetch-Metadata to reads (EventSource, images, navigations — those headers go only to trustworthy destinations), so an unmarked request may still be a rebound browser read with a readable response, and Host is the one header rebinding cannot forge; non-browser clients pass the same fence via loopback, the CLI-derived LAN IP literals, or a declared authority. When markers are present, an attached `Origin` must equal the Host authority, and an explicit `sec-fetch-site: cross-site` marker is refused. A `trustedHosts` entry that is not a bare, canonical `host[:port]` authority — one WHATWG parsing reads back exactly as written — fails the plugin load loudly: parsing would otherwise quietly authorize the hostname inside `harness.internal/path`, or broaden a dangling-colon or zero-padded port to an any-port grant. Failures answer plain 403 before any RPC dispatch. A non-loopback (`--host 0.0.0.0`) deployment therefore needs its serving authorities trusted: the dsh CLI derives the machine's LAN IP literals itself and its `--trusted-host` flag declares named ones, so `trustedHosts` in cordis.yml is for compositions the CLI does not boot. The fence is deliberately not an authentication layer — reachability policy stays with the webserver binding, and auth remains deferred work. Decision record: [the api browser-trust boundary Agent Note](../../../.agents/notes/implemented/architecture/2026-07-28-api-browser-trust-boundary.md).
+
 ## Keyless fixture
 
 Any `fixture` query parameter selects the in-memory carrier. `fixture=empty` starts with no Workspace or Session; `fixturePrompt=reject` rejects prompts before acceptance; `fixtureAttach=fail` publishes a Session but rejects its Workspace attachment; `fixtureSessionCreate=drop-response` publishes and frames a Session before dropping the create response; and `fixtureFrames=workspace-first` reverses the default session-first create-frame order. Workspace creation by name/path and caller-preallocated SessionIds remain deterministic enough for assembled Web tests to reconcile list and frame arrival.

packages/client/connection/README.zh.md

@@ -4,6 +4,10 @@
 
 协议消费层：客户端插件的 apply 会挂载 `ctx.connection`（共享 API 客户端 + 单消费方流循环启动器）；导出表层携带协议契约类型、`AbstractApiClient` seam，以及循环的 sink／配置类型。平台子类（WebApiClient/FixtureApiClient）、ConnectionController 循环和 fixture 数据源都属于包内部：apply 负责选择并驱动它们，测试则通过 src 访问。契约：api-contracts v3 §3。
 
+## /api 浏览器信任栅栏
+
+node 半侧在桥接前守卫 `/api` 下的每个请求（`src/api-request-trust.ts`）。每个请求——无论是否带浏览器标记——`Host` 都必须是回环地址权威，或与某个 `trustedHosts` 条目匹配：带端口的 `host:port` 条目精确匹配，不带端口的条目匹配任意端口，两侧均经 WHATWG 归一化后比较（DNS rebinding 防御）。刻意不为无浏览器标记的请求开捷径：明文 HTTP 下浏览器的读取（EventSource、图片、导航——这些头只发给可信目标）既不带 `Origin` 也不带 Fetch-Metadata，因此无标记请求仍可能是被重绑页面发起的、响应可被读走的读取，而 Host 是重绑唯一伪造不了的请求头；非浏览器客户端经由回环地址、CLI 推导的 LAN IP 字面量或已声明的权威通过同一道栅栏。当标记存在时，`Origin` 必须与 Host 权威完全一致；显式的 `sec-fetch-site: cross-site` 标记一律拒绝。不是纯的、规范形 `host[:port]` 权威的 `trustedHosts` 条目——即 WHATWG 解析读回后与原文不完全一致的——会让插件加载大声失败：否则解析会悄悄授权 `harness.internal/path` 这类笔误里的 hostname，或把悬空冒号、补零端口放大成任意端口授权。失败在任何 RPC 分发之前以纯 403 应答。因此非回环（`--host 0.0.0.0`）部署需要让自己的服务权威被信任：dsh CLI 会自行推导本机的 LAN IP 字面量，其 `--trusted-host` flag 用于声明具名权威，所以 cordis.yml 中的 `trustedHosts` 面向 CLI 不参与引导的组合。这道栅栏刻意不承担认证职责——可达性策略归 webserver 绑定配置，认证仍是延期工作。决策记录：[api 浏览器信任边界 Agent Note](../../../.agents/notes/implemented/architecture/2026-07-28-api-browser-trust-boundary.md)。
+
 ## 无密钥 fixture
 
 任何 `fixture` 查询参数都会选择内存载体。`fixture=empty` 启动时不含 Workspace 或 Session；`fixturePrompt=reject` 在接受前拒绝提示词；`fixtureAttach=fail` 发布 Session 但拒绝将其附加到 Workspace；`fixtureSessionCreate=drop-response` 在丢弃创建响应前发布 Session 并为其发出帧；`fixtureFrames=workspace-first` 则反转默认的 Session 优先创建帧顺序。按名称／路径创建 Workspace 以及由调用方预先分配 SessionId，均具有足够的确定性，组装后的 Web 测试可以据此协调列表与帧的到达。

packages/client/connection/package.json

@@ -33,7 +33,8 @@
     "@deepseek-ai/dsh-commands": "workspace:^",
     "@deepseek-ai/dsh-llm": "workspace:^",
     "@deepseek-ai/dsh-session": "workspace:^",
-    "@deepseek-ai/dsh-tools": "workspace:^"
+    "@deepseek-ai/dsh-tools": "workspace:^",
+    "schemastery": "^3.18.0"
   },
   "files": [
     "lib/index.js",

packages/client/connection/src/api-request-trust.ts

@@ -0,0 +1,129 @@
+/**
+ * Browser-trust fence for every /api request. Defends the two confused-deputy
+ * paths a browser opens against a local HTTP API — DNS rebinding (Host names
+ * the attacker's domain while the socket reaches this server) and cross-site
+ * requests fired from a malicious page. The Host fence binds every request,
+ * browser-looking or not: over plain HTTP a browser attaches neither Origin
+ * nor Fetch-Metadata to reads (EventSource, images, navigations — those
+ * headers go only to trustworthy destinations), so an unmarked request may
+ * still be a rebound browser read and Host is the one header rebinding cannot
+ * forge. Non-browser and remote clients pass the same fence via loopback, the
+ * CLI-derived LAN IP literals, or a declared `trustedHosts` authority.
+ * Network reachability and authentication stay out of scope: binding policy
+ * belongs to the webserver config, and this fence is not an auth layer.
+ */
+
+import type { IncomingHttpHeaders } from 'node:http'
+
+/** The request facts the fence reads (structural subset of IncomingMessage). */
+interface ApiTrustRequest {
+  headers: IncomingHttpHeaders
+}
+
+function header(headers: IncomingHttpHeaders, name: string): string | undefined {
+  const value = headers[name]
+  return typeof value === 'string' ? value : undefined
+}
+
+function isLoopbackHostname(hostname: string): boolean {
+  if (hostname === 'localhost' || hostname === '[::1]') return true
+  const parts = hostname.split('.')
+  return parts.length === 4
+    && parts[0] === '127'
+    && parts.every(part => /^\d{1,3}$/.test(part) && Number(part) <= 255)
+}
+
+/** Normalized URL of a Host-header authority (hostname lowercased, default port stripped, IPv6 bracketed), or undefined when unparsable. */
+function parseAuthority(authority: string): URL | undefined {
+  try {
+    // http: is a WHATWG "special scheme": parsing yields a non-empty hostname or throws.
+    return new URL(`http://${authority}`)
+  } catch {
+    return undefined
+  }
+}
+
+/**
+ * Assert one configured `trustedHosts` entry is a bare authority (`host` or
+ * `host:port`) in canonical form: it must survive WHATWG parsing unchanged
+ * (case aside). Anything parsing would silently rewrite is refused as a typo
+ * that must fail the load loudly instead of being ignored until requests 403
+ * or quietly changing the grant: URL parts beyond the authority
+ * (`harness.internal/path`, `user@harness.internal` — which would authorize
+ * the embedded hostname), stripped whitespace, a dangling colon or
+ * zero-padded port (which would broaden an intended exact-port grant to every
+ * port), and non-canonical host spellings (`0x7f.0.0.1`, percent-encoding,
+ * unbracketed IPv6; IDN hosts are declared in punycode, the form the wire
+ * carries).
+ * @param entry - the configured value, verbatim.
+ */
+export function assertTrustedAuthority(entry: string): void {
+  const entryUrl = parseAuthority(entry)
+  if (entryUrl !== undefined && canonicalAuthority(entry, entryUrl) === entry.toLowerCase()) return
+  throw new Error(`client-connection: trustedHosts entry ${JSON.stringify(entry)} is not a bare host[:port] authority`)
+}
+
+/**
+ * Canonical form of a parsed authority: `hostname` when no port was written,
+ * else `hostname:port`. The port is judged from URL parses under both special
+ * schemes (their default ports differ, so `:80` and `:443` still count as
+ * explicit), never from the raw string, where WHATWG trimming would misread
+ * shapes like `host:port ` as port-less.
+ */
+function canonicalAuthority(entry: string, entryUrl: URL): string {
+  // An authority that parsed under http cannot fail under https.
+  const port = entryUrl.port !== '' ? entryUrl.port : new URL(`https://${entry}`).port
+  return port === '' ? entryUrl.hostname : `${entryUrl.hostname}:${port}`
+}
+
+/**
+ * Whether the request authority matches a `trustedHosts` entry. An entry with
+ * an explicit port matches that exact authority; a port-less entry matches the
+ * hostname on any port (the shape the CLI derives for IP-literal LAN serving,
+ * where the bound port may be OS-assigned). Both sides compare through WHATWG
+ * normalization, so case and a redundant `:80` never decide trust.
+ */
+function isTrustedAuthority(hostUrl: URL, trustedHosts: readonly string[]): boolean {
+  return trustedHosts.some((entry) => {
+    const entryUrl = parseAuthority(entry)
+    if (entryUrl === undefined) return false
+    return canonicalAuthority(entry, entryUrl) === entryUrl.hostname
+      ? entryUrl.hostname === hostUrl.hostname
+      : entryUrl.host === hostUrl.host
+  })
+}
+
+/**
+ * Decide whether one /api request may reach the RPC bridge.
+ * @param request - node HTTP request facts (headers).
+ * @param trustedHosts - non-loopback authorities this deployment serves: exact `host:port`, or port-less `host` matching any port.
+ * @returns true when the Host is ours (loopback or trusted) and any attached browser markers are same-origin.
+ */
+export function isTrustedApiRequest(request: ApiTrustRequest, trustedHosts: readonly string[]): boolean {
+  // Host fence (DNS-rebinding defense), applied to every request: the browser
+  // fills Host from the URL it believes it is talking to, so a rebound page
+  // carries the attacker's domain here even though the socket lands on this
+  // server. There is no marker shortcut — a browser read over plain HTTP
+  // (EventSource, images, navigations) arrives with neither Origin nor
+  // Fetch-Metadata, indistinguishable from curl, and its response is readable
+  // by the rebound page.
+  const host = header(request.headers, 'host')
+  if (host === undefined) return false
+  const hostUrl = parseAuthority(host)
+  if (hostUrl === undefined) return false
+  if (!isLoopbackHostname(hostUrl.hostname) && !isTrustedAuthority(hostUrl, trustedHosts)) return false
+  // Cross-site fence: modern browsers label the initiator relationship on
+  // every fetch; an explicit cross-site marker is refused regardless of Origin.
+  if (header(request.headers, 'sec-fetch-site') === 'cross-site') return false
+  // Origin fence: when a browser attaches an Origin it must be exactly this
+  // authority (compared through the same normalization as the Host). Absent
+  // Origin is fine — the Host fence above already bound the request. The
+  // literal "null" (sandboxed iframes, file: pages) is an opaque origin, refused.
+  const origin = header(request.headers, 'origin')
+  if (origin === undefined) return true
+  try {
+    return new URL(origin).host === hostUrl.host
+  } catch {
+    return false
+  }
+}

packages/client/connection/src/client/api.ts

@@ -8,6 +8,7 @@
 export type {
   ApiProxy, SessionsApi, SessionSummary, HostApi, EventsApi, MuxFrame, HostFrame,
   ApprovalResponsePayload, QuestionResponsePayload, HistoryEntry, ToolEventView,
+  DirectoryEntry, DirectoryListing,
   WorkspaceApi, WorkspaceId, WorkspaceView,
   CommandsApi, CommandDescriptor, SkillsApi, SkillEntry,
   ModelCatalogFailure, ModelCatalogModel, ModelProviderGroup, ModelReasoning,

packages/client/connection/src/client/fixture.ts

@@ -575,6 +575,37 @@ export function createFixtureApi(options: FixtureOptions = {}): ApiProxy {
     updatedAt: fixtureEpoch,
   }]
   let nextWorkspace = 1
+
+  // In-memory browse tree behind the fixture's `browse` picker capability —
+  // deterministic content mirroring the design mock so assembled Web tests
+  // and snapshots can walk it. Leaves are materialized lazily: a child listed
+  // by its parent lists as empty until something is created inside it.
+  const FIXTURE_HOME = '/home/fixture'
+  const directoryTree = new Map<string, string[]>([
+    ['/', ['home']],
+    ['/home', ['fixture']],
+    [FIXTURE_HOME, ['Documents', 'Downloads', '.config']],
+    [`${FIXTURE_HOME}/Documents`, [
+      'project', 'deepseek-iOS', 'deepseek-android', 'deepseek-platform',
+      'deepseek-web', 'deepseek-harness', 'deepseek-app', 'deepseek-landing-blog',
+    ]],
+  ])
+  const childrenOf = (path: string): string[] | undefined => {
+    const known = directoryTree.get(path)
+    if (known !== undefined) return known
+    const parent = path.slice(0, path.lastIndexOf('/')) || '/'
+    const name = path.slice(path.lastIndexOf('/') + 1)
+    return directoryTree.get(parent)?.includes(name) === true ? [] : undefined
+  }
+  const crumbsOf = (path: string): { name: string; path: string; hidden: boolean }[] => {
+    const crumbs = [{ name: '/', path: '/', hidden: false }]
+    let acc = ''
+    for (const segment of path.split('/').filter(Boolean)) {
+      acc += `/${segment}`
+      crumbs.push({ name: segment, path: acc, hidden: false })
+    }
+    return crumbs
+  }
   const mint = (): ReturnType<typeof RpcId> => RpcId(`fx-rpc-${nextRpc++}`)
   /** Resident pending approval (stable rpcId: every mux open replays the same id, matching host replay semantics). */
   const pendingApprovalRpcId = mint()
@@ -980,7 +1011,42 @@ export function createFixtureApi(options: FixtureOptions = {}): ApiProxy {
     },
     host: {
       describe: request => ok(request, { version: '0.0.0-fixture', cwd: '/tmp/fixture', attachedSessions }),
-      pickDirectory: request => ok(request, { path: null }),
+      // Deterministic native pick: the keyless lanes drive the full
+      // pick-then-adopt path without an OS chooser (design-mock content,
+      // same tree the browse primitives serve).
+      pickDirectory: request => ok(request, { path: `${FIXTURE_HOME}/Documents/project` }),
+      listDirectory: (request) => {
+        const target = request.payload.path ?? FIXTURE_HOME
+        const children = childrenOf(target)
+        if (children === undefined) {
+          return err(request, { code: 'directory-unreadable', message: `cannot list ${target}: not in the fixture tree`, details: { path: target } })
+        }
+        return ok(request, {
+          path: target,
+          home: FIXTURE_HOME,
+          crumbs: crumbsOf(target),
+          entries: [...children].sort((a, b) => a.localeCompare(b))
+            .map(name => ({ name, path: target === '/' ? `/${name}` : `${target}/${name}`, hidden: name.startsWith('.') })),
+          // The fixture tree is tiny; no level ever reaches a backend bound.
+          truncated: false,
+        })
+      },
+      createDirectory: (request) => {
+        const parent = request.payload.path
+        const children = childrenOf(parent)
+        if (children === undefined) {
+          return err(request, { code: 'directory-create-failed', message: `missing parent ${parent}`, details: { path: parent } })
+        }
+        // Same root special case as listDirectory's entry paths: a plain join
+        // under '/' would mint '//name' and fork the tree's identity.
+        const target = parent === '/' ? `/${request.payload.name}` : `${parent}/${request.payload.name}`
+        if (children.includes(request.payload.name)) {
+          return err(request, { code: 'directory-exists', message: `${target} already exists`, details: { path: target } })
+        }
+        directoryTree.set(parent, [...children, request.payload.name])
+        directoryTree.set(target, [])
+        return ok(request, { path: target })
+      },
       openPath: request => ok(request, { opened: true as const }),
     },
     workspace: {
@@ -1335,6 +1401,8 @@ export class FixtureApiClient extends AbstractApiClient {
       case 'session.cancel': return this.api.sessions.cancel(request)
       case 'host.describe': return this.api.host.describe(request)
       case 'host.pickDirectory': return this.api.host.pickDirectory(request, new AbortController().signal)
+      case 'host.listDirectory': return this.api.host.listDirectory(request, new AbortController().signal)
+      case 'host.createDirectory': return this.api.host.createDirectory(request)
       case 'host.openPath': return this.api.host.openPath(request, new AbortController().signal)
       case 'workspace.list': return this.api.workspace.list(request)
       case 'workspace.create': return this.api.workspace.create(request)

packages/client/connection/src/client/index.ts

@@ -13,6 +13,7 @@ import { WebApiClient } from './web-api-client.ts'
 export type {
   ApiProxy, SessionsApi, SessionSummary, HostApi, EventsApi, MuxFrame, HostFrame,
   ApprovalResponsePayload, QuestionResponsePayload, HistoryEntry, ToolEventView,
+  DirectoryEntry, DirectoryListing,
   ToolCallView, ToolResultView, WorkspaceApi, WorkspaceId, WorkspaceView,
   CommandsApi, CommandDescriptor, SkillsApi, SkillEntry,
   ModelCatalogFailure, ModelCatalogModel, ModelProviderGroup, ModelReasoning,

packages/client/connection/src/index.ts

@@ -1,11 +1,12 @@
 /** Host HTTP bridge for browser-client RPC. */
 import type { Context } from 'cordis'
+import z from 'schemastery'
 // Activates the httpServer Context merge used below.
 import type { WebRoute } from '@deepseek-ai/dsh-host-webserver'
 import { toFetchHandler } from '@deepseek-ai/dsh-host-apiproxy'
 import { API_PATH } from './api-path.ts'
 import { bridge } from './http-bridge.ts'
-import { isTrustedNativeDialogRequest } from './native-dialog-request.ts'
+import { assertTrustedAuthority, isTrustedApiRequest } from './api-request-trust.ts'
 
 export { API_PATH } from './api-path.ts'
 
@@ -15,20 +16,42 @@ export const name = 'client-connection'
 /** Services required before mounting the route. */
 export const inject = ['httpServer', 'apiProxy']
 
+/** Plugin config: the deployment's non-loopback serving authorities. */
+export interface ConnectionConfig {
+  /**
+   * Authorities this deployment serves beyond loopback: exact `host:port`, or
+   * port-less `host` matching any port. The /api trust fence refuses any
+   * request whose Host is neither loopback nor listed here, so a
+   * non-loopback (`0.0.0.0`) deployment must declare the names it is reached
+   * by (the dsh CLI derives the machine's LAN IP literals itself). An entry
+   * that is not a bare, canonical authority fails the plugin load.
+   */
+  trustedHosts?: string[]
+}
+
+export const Config: z<ConnectionConfig> = z.object({
+  trustedHosts: z.array(String).default([]),
+})
+
 /**
- * Mounts the API gateway under the browser transport prefix.
+ * Mounts the API gateway under the browser transport prefix. Every request on
+ * the prefix passes the browser-trust fence first (DNS-rebinding and
+ * cross-site defense — [api-request-trust](./api-request-trust.ts)).
  * @param ctx - Host plugin context.
+ * @param config - resolved plugin config (schema defaults applied).
  */
-export function apply(ctx: Context): void {
+export function apply(ctx: Context, config?: ConnectionConfig): void {
+  // The Loader resolves schema defaults; hand-built test contexts may pass none.
+  const trustedHosts = config?.trustedHosts ?? []
+  // Config boundary: a malformed entry fails the load loudly here rather than
+  // silently authorizing its hostname prefix at request time.
+  for (const entry of trustedHosts) assertTrustedAuthority(entry)
   const apiHandler = toFetchHandler(ctx.apiProxy)
   const route: WebRoute = {
     kind: 'prefix',
     path: API_PATH,
     handler: async (req, res) => {
-      const pathname = new URL(req.url ?? '/', 'http://dsh.internal').pathname
-      if ((pathname === `${API_PATH}/host.pickDirectory`
-        || pathname === `${API_PATH}/host.openPath`)
-        && !isTrustedNativeDialogRequest(req)) {
+      if (!isTrustedApiRequest(req, trustedHosts)) {
         res.writeHead(403)
         res.end('forbidden')
         return

packages/client/connection/src/native-dialog-request.ts

@@ -1,52 +0,0 @@
-/** Trust check for browser requests that can invoke privileged native host actions. */
-
-import type { IncomingHttpHeaders } from 'node:http'
-
-interface NativeDialogRequest {
-  headers: IncomingHttpHeaders
-  socket: { remoteAddress?: string | undefined }
-}
-
-function header(headers: IncomingHttpHeaders, name: string): string | undefined {
-  const value = headers[name]
-  return typeof value === 'string' ? value : undefined
-}
-
-function isLoopback(address: string | undefined): boolean {
-  if (address === undefined) return false
-  if (address === '::1') return true
-  const ipv4 = address.startsWith('::ffff:') ? address.slice('::ffff:'.length) : address
-  const first = ipv4.split('.')[0]
-  return first === '127'
-}
-
-function isLoopbackHostname(hostname: string): boolean {
-  if (hostname === 'localhost' || hostname === '[::1]' || hostname === '::1') return true
-  const parts = hostname.split('.')
-  return parts.length === 4
-    && parts[0] === '127'
-    && parts.every(part => /^\d{1,3}$/.test(part) && Number(part) <= 255)
-}
-
-/**
- * Require a local socket plus browser-controlled same-origin metadata.
- * @param request - the node HTTP request facts used by the carrier guard.
- * @returns true only for a same-origin browser request whose peer and URL are loopback.
- */
-export function isTrustedNativeDialogRequest(request: NativeDialogRequest): boolean {
-  if (!isLoopback(request.socket.remoteAddress)) return false
-  if (header(request.headers, 'sec-fetch-site') !== 'same-origin') return false
-  const origin = header(request.headers, 'origin')
-  const host = header(request.headers, 'host')
-  if (origin === undefined || host === undefined) return false
-  try {
-    const parsed = new URL(origin)
-    const hostUrl = new URL(`http://${host}`)
-    return (parsed.protocol === 'http:' || parsed.protocol === 'https:')
-      && parsed.host === host
-      && isLoopbackHostname(parsed.hostname)
-      && isLoopbackHostname(hostUrl.hostname)
-  } catch {
-    return false
-  }
-}

packages/client/connection/tests/api-request-trust.spec.ts

@@ -0,0 +1,108 @@
+/** Behavior of the /api browser-trust fence (rebinding + cross-site defense). */
+
+import { describe, expect, it } from 'vitest'
+import { assertTrustedAuthority, isTrustedApiRequest } from '../src/api-request-trust.ts'
+
+function request(headers: Record<string, string | undefined>): { headers: Record<string, string | undefined> } {
+  return { headers }
+}
+
+describe('isTrustedApiRequest', () => {
+  it('holds markerless requests to the same Host fence — a plain-HTTP browser read carries no markers', () => {
+    // Over plain HTTP a browser attaches neither Origin nor Fetch-Metadata to
+    // reads (EventSource, images, navigations), so a rebound-origin GET is
+    // markerless and its response readable: no marker shortcut may exist.
+    expect(isTrustedApiRequest(request({ host: '127.0.0.1:3080' }), [])).toBe(true)
+    expect(isTrustedApiRequest(request({ host: '192.168.1.5:3080' }), ['192.168.1.5'])).toBe(true)
+    expect(isTrustedApiRequest(request({ host: '192.168.1.5:3080' }), [])).toBe(false)
+    expect(isTrustedApiRequest(request({ host: 'harness.example' }), [])).toBe(false)
+    expect(isTrustedApiRequest(request({}), [])).toBe(false)
+  })
+
+  it('accepts loopback Hosts in every spelling, with and without ports, for browser requests', () => {
+    for (const host of ['localhost', 'localhost:3080', '127.0.0.1', '127.0.0.1:3080', '127.8.9.10:80', '[::1]', '[::1]:3080', 'LOCALHOST:3080']) {
+      expect(isTrustedApiRequest(request({ host, origin: `http://${host}` }), [])).toBe(true)
+    }
+  })
+
+  it('refuses a rebound Host: the attacker domain names the socket it did not expect', () => {
+    expect(isTrustedApiRequest(request({
+      host: 'evil.example:3080',
+      origin: 'http://evil.example:3080',
+      'sec-fetch-site': 'same-origin',
+    }), [])).toBe(false)
+  })
+
+  it('accepts a declared public authority: exact on host:port entries, any port on port-less entries', () => {
+    const headers = { host: 'harness.internal:3080', origin: 'http://harness.internal:3080' }
+    expect(isTrustedApiRequest(request(headers), ['harness.internal:3080'])).toBe(true)
+    expect(isTrustedApiRequest(request(headers), ['harness.internal'])).toBe(true)
+    expect(isTrustedApiRequest(request(headers), ['harness.internal:9999'])).toBe(false)
+    expect(isTrustedApiRequest(request(headers), [])).toBe(false)
+  })
+
+  it('matches Host, Origin, and trusted entries through WHATWG normalization (case, default port)', () => {
+    expect(isTrustedApiRequest(request({ host: 'Harness.INTERNAL:3080', origin: 'http://harness.internal:3080' }), ['harness.internal:3080'])).toBe(true)
+    expect(isTrustedApiRequest(request({ host: 'harness.internal', origin: 'http://harness.internal' }), ['HARNESS.internal:80'])).toBe(true)
+    // An unparsable entry never matches; it must not poison the rest of the list.
+    expect(isTrustedApiRequest(request({ host: 'harness.internal', origin: 'http://harness.internal' }), ['bad entry', 'harness.internal'])).toBe(true)
+    expect(isTrustedApiRequest(request({ host: 'harness.internal', origin: 'http://harness.internal' }), ['bad entry'])).toBe(false)
+  })
+
+  it('refuses cross-origin browser markers even on a loopback Host', () => {
+    // Origin present and different → cross-site request that survived preflight rules.
+    expect(isTrustedApiRequest(request({ host: '127.0.0.1:3080', origin: 'http://evil.example' }), [])).toBe(false)
+    // Explicit cross-site label → refused regardless of Origin.
+    expect(isTrustedApiRequest(request({ host: '127.0.0.1:3080', 'sec-fetch-site': 'cross-site' }), [])).toBe(false)
+    // Opaque origin (sandboxed iframe, file: page) parses to no authority.
+    expect(isTrustedApiRequest(request({ host: '127.0.0.1:3080', origin: 'null' }), [])).toBe(false)
+  })
+
+  it('accepts a same-origin browser request, with or without an Origin header', () => {
+    expect(isTrustedApiRequest(request({
+      host: 'localhost:3080',
+      origin: 'http://localhost:3080',
+      'sec-fetch-site': 'same-origin',
+    }), [])).toBe(true)
+    // Origin-less browser shapes (same-origin GETs) still carry sec-fetch-site.
+    expect(isTrustedApiRequest(request({ host: 'localhost:3080', 'sec-fetch-site': 'same-origin' }), [])).toBe(true)
+  })
+
+  it('assertTrustedAuthority accepts bare authorities and throws on anything more', () => {
+    for (const entry of ['harness.internal', 'harness.internal:3080', 'HARNESS.internal:80', '10.0.0.9', '[::1]:3080']) {
+      expect(() => { assertTrustedAuthority(entry) }).not.toThrow()
+    }
+    // WHATWG parsing would quietly read a hostname out of each of these; the
+    // config boundary must refuse them instead of authorizing the prefix.
+    for (const entry of ['harness.internal/path', 'harness.internal/', 'user@harness.internal', 'harness.internal?x', 'harness.internal#f', 'harness.internal\\path', 'bad entry', '']) {
+      expect(() => { assertTrustedAuthority(entry) }).toThrow(/not a bare host\[:port\] authority/)
+    }
+    // WHATWG trimming would silently strip these; the entry must fail instead.
+    for (const entry of ['harness.internal:3080 ', ' harness.internal', 'harness.internal:30\t80']) {
+      expect(() => { assertTrustedAuthority(entry) }).toThrow(/not a bare host\[:port\] authority/)
+    }
+    // WHATWG parsing would silently rewrite these — a dangling colon or
+    // zero-padded port would broaden an intended exact-port grant to every
+    // port, and non-canonical host spellings would not read back as written.
+    for (const entry of ['harness.internal:', '[::1]:', 'harness.internal:0080', '0x7f.0.0.1', '[0:0:0:0:0:0:0:1]']) {
+      expect(() => { assertTrustedAuthority(entry) }).toThrow(/not a bare host\[:port\] authority/)
+    }
+  })
+
+  it('never lets stray whitespace broaden an exact-port entry to every port', () => {
+    // Defense in depth below the load-time assert: the explicit-port judgment
+    // reads the parsed URL, so a trimmed `host:port ` entry stays exact.
+    const trusted = ['harness.internal:3080 ']
+    expect(isTrustedApiRequest(request({ host: 'harness.internal:9999', origin: 'http://harness.internal:9999' }), trusted)).toBe(false)
+    expect(isTrustedApiRequest(request({ host: 'harness.internal:3080', origin: 'http://harness.internal:3080' }), trusted)).toBe(true)
+  })
+
+  it('refuses malformed or untrusted authorities on browser requests', () => {
+    const markers = { 'sec-fetch-site': 'same-origin' }
+    expect(isTrustedApiRequest(request({ ...markers }), [])).toBe(false)
+    expect(isTrustedApiRequest(request({ ...markers, host: '' }), [])).toBe(false)
+    expect(isTrustedApiRequest(request({ ...markers, host: 'bad host' }), [])).toBe(false)
+    expect(isTrustedApiRequest(request({ ...markers, host: '127.0.0.999' }), [])).toBe(false)
+    expect(isTrustedApiRequest(request({ ...markers, host: '128.0.0.1' }), [])).toBe(false)
+  })
+})

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

@@ -70,6 +70,18 @@ export class FakeApiClient implements IApiClient {
   onOpenPath: (payload: unknown) => Promise<RpcResponse<{ opened: true }>> =
     () => Promise.resolve(ok({ opened: true as const }))
 
+  onListDirectory: (payload: unknown) => Promise<RpcResponse<{
+    path: string
+    home: string
+    crumbs: { name: string; path: string; hidden: boolean }[]
+    entries: { name: string; path: string; hidden: boolean }[]
+    truncated: boolean
+  }>> =
+    () => Promise.resolve(ok({ path: '/home/fake', home: '/home/fake', crumbs: [{ name: '/', path: '/', hidden: false }], entries: [], truncated: false }))
+
+  onCreateDirectory: (payload: unknown) => Promise<RpcResponse<{ path: string }>> =
+    () => Promise.resolve(ok({ path: '/home/fake/new' }))
+
   private readonly muxConns: StreamConn<MuxFrame>[] = []
   private readonly hostConns: StreamConn<HostFrame>[] = []
 
@@ -91,6 +103,8 @@ export class FakeApiClient implements IApiClient {
   readonly host: IApiClient['host'] = {
     describe: payload => this.record('host.describe', payload, this.onDescribe(payload)),
     pickDirectory: payload => this.record('host.pickDirectory', payload, this.onPickDirectory(payload)),
+    listDirectory: payload => this.record('host.listDirectory', payload, this.onListDirectory(payload)),
+    createDirectory: payload => this.record('host.createDirectory', payload, this.onCreateDirectory(payload)),
     openPath: payload => this.record('host.openPath', payload, this.onOpenPath(payload)),
   }
 

packages/client/connection/tests/fixture.spec.ts

@@ -319,6 +319,22 @@ describe('createFixtureApi', () => {
     expect(empty.result).toMatchObject({ ok: true, value: { attachedSessions: 0 } })
   })
 
+  it('createDirectory under the root mints /name whose listing and crumbs share the identity', async () => {
+    const api = createFixtureApi()
+    const created = await api.host.createDirectory(req({ path: '/', name: 'srv' }))
+    if (!created.result.ok) throw new Error('create failed')
+    expect(created.result.value.path).toBe('/srv')
+    const listed = await api.host.listDirectory(req({ path: '/srv' }), new AbortController().signal)
+    if (!listed.result.ok) throw new Error('list failed')
+    expect(listed.result.value.crumbs).toEqual([
+      { name: '/', path: '/', hidden: false },
+      { name: 'srv', path: '/srv', hidden: false },
+    ])
+    const root = await api.host.listDirectory(req({ path: '/' }), new AbortController().signal)
+    if (!root.result.ok) throw new Error('root list failed')
+    expect(root.result.value.entries).toContainEqual({ name: 'srv', path: '/srv', hidden: false })
+  })
+
   it('workspace.list serves the resident account and create reuses on path collision', async () => {
     const api = createFixtureApi()
     const listed = await api.workspace.list(req({}))

packages/client/connection/tests/native-dialog-request.spec.ts

@@ -1,57 +0,0 @@
-import type { IncomingHttpHeaders } from 'node:http'
-import { describe, expect, it } from 'vitest'
-import { isTrustedNativeDialogRequest } from '../src/native-dialog-request.ts'
-
-function request(
-  remoteAddress: string | undefined,
-  headers: IncomingHttpHeaders = {
-    host: '127.0.0.1:3080',
-    origin: 'http://127.0.0.1:3080',
-    'sec-fetch-site': 'same-origin',
-  },
-) {
-  return { socket: { remoteAddress }, headers }
-}
-
-describe('native dialog request trust', () => {
-  it('accepts loopback same-origin browser requests', () => {
-    expect(isTrustedNativeDialogRequest(request('127.0.0.1'))).toBe(true)
-    expect(isTrustedNativeDialogRequest(request('::1', {
-      host: '[::1]:3080', origin: 'http://[::1]:3080', 'sec-fetch-site': 'same-origin',
-    }))).toBe(true)
-    expect(isTrustedNativeDialogRequest(request('::ffff:127.0.0.1'))).toBe(true)
-    expect(isTrustedNativeDialogRequest(request('127.0.0.1', {
-      host: 'localhost:3080', origin: 'http://localhost:3080', 'sec-fetch-site': 'same-origin',
-    }))).toBe(true)
-    expect(isTrustedNativeDialogRequest(request('127.0.0.2', {
-      host: '127.0.0.2:3080', origin: 'https://127.0.0.2:3080', 'sec-fetch-site': 'same-origin',
-    }))).toBe(true)
-  })
-
-  it('rejects remote sockets and requests without matching browser metadata', () => {
-    expect(isTrustedNativeDialogRequest(request('192.168.1.5'))).toBe(false)
-    expect(isTrustedNativeDialogRequest(request(undefined))).toBe(false)
-    expect(isTrustedNativeDialogRequest(request('127.0.0.1', {
-      host: '127.0.0.1:3080', origin: 'http://evil.example', 'sec-fetch-site': 'cross-site',
-    }))).toBe(false)
-    expect(isTrustedNativeDialogRequest(request('127.0.0.1', {
-      host: '127.0.0.1:3080', origin: 'http://localhost:3080', 'sec-fetch-site': 'same-origin',
-    }))).toBe(false)
-    expect(isTrustedNativeDialogRequest(request('127.0.0.1', { host: '127.0.0.1:3080' }))).toBe(false)
-    expect(isTrustedNativeDialogRequest(request('127.0.0.1', {
-      origin: 'http://127.0.0.1:3080', 'sec-fetch-site': 'same-origin',
-    }))).toBe(false)
-    expect(isTrustedNativeDialogRequest(request('127.0.0.1', {
-      host: 'attacker.example:3080', origin: 'http://attacker.example:3080', 'sec-fetch-site': 'same-origin',
-    }))).toBe(false)
-    expect(isTrustedNativeDialogRequest(request('127.0.0.1', {
-      host: '127.0.0.1:3080', origin: 'ftp://127.0.0.1:3080', 'sec-fetch-site': 'same-origin',
-    }))).toBe(false)
-    expect(isTrustedNativeDialogRequest(request('127.0.0.1', {
-      host: '127.999.0.1:3080', origin: 'http://127.999.0.1:3080', 'sec-fetch-site': 'same-origin',
-    }))).toBe(false)
-    expect(isTrustedNativeDialogRequest(request('127.0.0.1', {
-      host: '[invalid', origin: 'http://[invalid', 'sec-fetch-site': 'same-origin',
-    }))).toBe(false)
-  })
-})

packages/client/connection/tests/node-half.spec.ts

@@ -1,4 +1,6 @@
 /** Node half: registers the /api prefix route bridging to the api gateway. */
+import { EventEmitter } from 'node:events'
+import { Readable } from 'node:stream'
 import { Context } from 'cordis'
 import { describe, expect, it } from 'vitest'
 import type { IncomingMessage, ServerResponse } from 'node:http'
@@ -6,48 +8,113 @@ import type { ApiProxy } from '@deepseek-ai/dsh-host-apiproxy/api'
 import type { HttpServerService, WebRoute } from '@deepseek-ai/dsh-host-webserver'
 import { API_PATH, apply, inject } from '../src/index.ts'
 
-describe('connection node half', () => {
-  it('registers the /api prefix route and removes it with the fiber', async () => {
-    const ctx = new Context()
-    const routes: WebRoute[] = []
-    // Structural fake: the plugin only touches register(); the service class
-    // carries private state a literal cannot (and need not) reproduce.
-    const httpServer: Pick<HttpServerService, 'register' | 'tapIndex' | 'port'> = {
-      register(route) {
-        routes.push(route)
-        return () => { routes.splice(routes.indexOf(route), 1) }
-      },
-      tapIndex: () => () => {},
-      port: 0,
-    }
-    ctx.provide('httpServer', httpServer as HttpServerService)
-    ctx.provide('apiProxy', {} as unknown as ApiProxy)
+/** Structural httpServer fake: the plugin only touches register(). */
+function fakeHttpServer(routes: WebRoute[]): Pick<HttpServerService, 'register' | 'tapIndex' | 'port'> {
+  return {
+    register(route) {
+      routes.push(route)
+      return () => { routes.splice(routes.indexOf(route), 1) }
+    },
+    tapIndex: () => () => {},
+    port: 0,
+  }
+}
 
-    const fiber = ctx.plugin({ inject: [...inject], apply })
-    await fiber.await()
+/** Bodyless GET carrying the given headers (enough for the trust fence + bridge). */
+function fakeRequest(headers: Record<string, string>): IncomingMessage {
+  const request = Readable.from([]) as unknown as IncomingMessage
+  Object.assign(request, { url: `${API_PATH}/session.list`, method: 'GET', headers })
+  return request
+}
+
+/** Response recorder compatible with both the fence's short-circuit and the bridge. */
+function fakeResponse(): { response: ServerResponse; state: { status?: number; body?: unknown } } {
+  const state: { status?: number; body?: unknown } = {}
+  const response = Object.assign(new EventEmitter(), {
+    writableEnded: false,
+    writeHead(value: number) { state.status = value; return this },
+    write() { return true },
+    end(this: { writableEnded: boolean }, value?: unknown) {
+      if (value !== undefined) state.body = value
+      this.writableEnded = true
+      return this
+    },
+  }) as unknown as ServerResponse
+  return { response, state }
+}
+
+async function mounted(config?: { trustedHosts?: string[] }): Promise<{ routes: WebRoute[]; dispose: () => Promise<void> }> {
+  const ctx = new Context()
+  const routes: WebRoute[] = []
+  ctx.provide('httpServer', fakeHttpServer(routes) as HttpServerService)
+  ctx.provide('apiProxy', {} as unknown as ApiProxy)
+  const fiber = ctx.plugin({ inject: [...inject], apply }, config)
+  await fiber.await()
+  return { routes, dispose: () => fiber.dispose() }
+}
+
+describe('connection node half', () => {
+  it('fails the load on a trustedHosts entry that is not a bare authority', async () => {
+    const routes: WebRoute[] = []
+    const ctx = new Context()
+    ctx.provide('httpServer', fakeHttpServer(routes) as HttpServerService)
+    ctx.provide('apiProxy', {} as unknown as ApiProxy)
+    // The apply throw also escapes cordis as a late rejection — the shape the
+    // boot's installFailLoud is contracted to catch. Capture it so the run
+    // stays clean, same pattern as the webserver bind-failure test.
+    const rejections: unknown[] = []
+    const onUnhandled = (err: unknown): void => { rejections.push(err) }
+    process.on('unhandledRejection', onUnhandled)
+    try {
+      const fiber = ctx.plugin({ inject: [...inject], apply }, { trustedHosts: ['harness.internal/path'] })
+      await expect(fiber.await()).rejects.toThrow(/not a bare host\[:port\] authority/)
+      expect(routes).toHaveLength(0)
+      for (let i = 0; i < 100 && rejections.length === 0; i++) {
+        await new Promise(resolve => setTimeout(resolve, 10))
+      }
+      expect(rejections.map(String).join('\n')).toContain('not a bare host[:port] authority')
+    } finally {
+      process.off('unhandledRejection', onUnhandled)
+    }
+  })
+
+  it('registers the /api prefix route and removes it with the fiber', async () => {
+    const { routes, dispose } = await mounted()
     expect(routes).toHaveLength(1)
     expect(routes[0]).toMatchObject({ kind: 'prefix', path: API_PATH })
-
-    for (const url of ['/api/host.pickDirectory', '/api/host.openPath']) {
-      let status: number | undefined
-      let body: unknown
-      const deniedRequest = {
-        url,
-        headers: {
-          host: 'harness.example', origin: 'http://harness.example', 'sec-fetch-site': 'same-origin',
-        },
-        socket: { remoteAddress: '192.168.1.8' },
-      } as unknown as IncomingMessage
-      const deniedResponse = {
-        writeHead(value: number) { status = value; return this },
-        end(value?: unknown) { body = value; return this },
-      } as unknown as ServerResponse
-      await routes[0]!.handler(deniedRequest, deniedResponse)
-      expect(status).toBe(403)
-      expect(body).toBe('forbidden')
-    }
-
-    await fiber.dispose()
+    await dispose()
     expect(routes).toHaveLength(0)
   })
+
+  it('refuses an untrusted Host on any /api path before the bridge runs', async () => {
+    const { routes, dispose } = await mounted()
+    const { response, state } = fakeResponse()
+    await routes[0]!.handler(fakeRequest({
+      host: 'harness.example', origin: 'http://harness.example', 'sec-fetch-site': 'same-origin',
+    }), response)
+    expect(state.status).toBe(403)
+    expect(state.body).toBe('forbidden')
+    await dispose()
+  })
+
+  it('passes loopback and declared-authority requests through to the bridge', async () => {
+    const { routes, dispose } = await mounted({ trustedHosts: ['harness.example:3080', '192.168.1.5'] })
+    // Loopback, no browser markers (curl shape): the fence passes; the carrier
+    // answers 404 for a GET unary path — proof the bridge ran.
+    const loopback = fakeResponse()
+    await routes[0]!.handler(fakeRequest({ host: '127.0.0.1:3080' }), loopback.response)
+    expect(loopback.state.status).toBe(404)
+    // LAN authority declared as a port-less IP literal — the shape the CLI
+    // derives for `--host 0.0.0.0` — passes markerless curl on any port.
+    const lan = fakeResponse()
+    await routes[0]!.handler(fakeRequest({ host: '192.168.1.5:3080' }), lan.response)
+    expect(lan.state.status).toBe(404)
+    // Declared public authority, same-origin browser shape.
+    const declared = fakeResponse()
+    await routes[0]!.handler(fakeRequest({
+      host: 'harness.example:3080', origin: 'http://harness.example:3080', 'sec-fetch-site': 'same-origin',
+    }), declared.response)
+    expect(declared.state.status).toBe(404)
+    await dispose()
+  })
 })

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

@@ -6,7 +6,7 @@
  * the concrete class. Widening this interface is the explicit act of
  * widening what features may do to the workspaces domain.
  */
-import type { SessionId, WorkspaceId, WorkspaceView } from '@deepseek-ai/dsh-client-connection/client'
+import type { DirectoryListing, SessionId, WorkspaceId, WorkspaceView } from '@deepseek-ai/dsh-client-connection/client'
 import type { WorkspaceListState } from '../workspaces/service.ts'
 import type { ObservableSnapshot } from './store.ts'
 
@@ -37,6 +37,20 @@ export interface IWorkspaces {
    * @returns the selected path, or null when the user cancelled.
    */
   pickDirectory(): Promise<string | null>
+  /**
+   * List one directory level through the Host's `browse` capability.
+   * @param path - absolute directory to list; absent lists the Host home directory.
+   * @param signal - aborts the wire request (and the Host's scan) when the caller supersedes it.
+   * @returns the level's listing with breadcrumb ancestry.
+   */
+  listDirectory(path?: string, signal?: AbortSignal): Promise<DirectoryListing>
+  /**
+   * Create one child directory through the Host's `browse` capability.
+   * @param path - absolute existing parent directory.
+   * @param name - single non-blank path segment.
+   * @returns the created directory's absolute path.
+   */
+  createDirectory(path: string, name: string): Promise<string>
   /**
    * Open a filesystem path with the Host operating system's default application.
    * @param path - absolute or host-resolvable path.

packages/client/runtime/src/client/index.ts

@@ -18,7 +18,7 @@ export { SessionProvideChannel } from './sessions/provide.ts'
 export type { SessionProvideChannelHost } from './sessions/provide.ts'
 export { createScope } from './agents/scope.ts'
 export type { AgentScopeHandle } from './agents/scope.ts'
-export { WorkspaceCreateError, WorkspacesService } from './workspaces/service.ts'
+export { DirectoryBrowseError, WorkspaceCreateError, WorkspacesService } from './workspaces/service.ts'
 export type { Session } from './sessions/session.ts'
 export type { ISession, ProjectionsFace, SessionFace } from './contract/session.ts'
 export type { ISessions } from './contract/sessions.ts'
@@ -29,7 +29,9 @@ export type {
 export type { SessionListPhase } from './sessions/manager.ts'
 export type { WorkspaceListPhase } from './workspaces/manager.ts'
 export type { WorkspaceListState } from './workspaces/service.ts'
-export type { WorkspaceId, WorkspaceView } from '@deepseek-ai/dsh-client-connection/client'
+export type {
+  DirectoryEntry, DirectoryListing, WorkspaceId, WorkspaceView,
+} from '@deepseek-ai/dsh-client-connection/client'
 // Runtime owns the snapshot store; web-react only binds it to React.
 export { createSnapshotStore, defineStore, shallowEqual } from './contract/store.ts'
 export type {

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

@@ -2,7 +2,8 @@
 
 import type { Context } from 'cordis'
 import type {
-  IApiClient, RpcError, SessionId, WorkspaceId, WorkspaceView,
+  DirectoryListing, IApiClient, RpcError,
+  SessionId, WorkspaceId, WorkspaceView,
 } from '@deepseek-ai/dsh-client-connection/client'
 import type { SnapshotStore } from '../contract/store.ts'
 import { createSnapshotStore } from '../contract/store.ts'
@@ -30,6 +31,14 @@ export class WorkspaceCreateError extends Error {
   }
 }
 
+/** Structured browse failure so the directory browser can branch on Host business codes. */
+export class DirectoryBrowseError extends Error {
+  constructor(readonly rpcError: RpcError) {
+    super(`directory browse failed: ${rpcError.code}: ${rpcError.message}`)
+    this.name = 'DirectoryBrowseError'
+  }
+}
+
 /** Real Workspace object layer and Host actions. */
 export class WorkspacesService implements IWorkspaces {
   /** UI-facing immutable projection; the manager remains wire truth. */
@@ -172,7 +181,7 @@ export class WorkspacesService implements IWorkspaces {
   }
 
   /**
-   * Open the Host's native directory picker.
+   * Open the Host's native directory picker (the `native` capability).
    * @returns the selected path, or null when the user cancelled.
    */
   async pickDirectory(): Promise<string | null> {
@@ -183,6 +192,30 @@ export class WorkspacesService implements IWorkspaces {
     return response.result.value.path
   }
 
+  /**
+   * List one directory level through the Host's `browse` capability.
+   * @param path - absolute directory to list; absent lists the Host home directory.
+   * @param signal - aborts the wire request (and the Host's scan) when the caller supersedes it.
+   * @returns the level's listing with breadcrumb ancestry.
+   */
+  async listDirectory(path?: string, signal?: AbortSignal): Promise<DirectoryListing> {
+    const response = await this.api.host.listDirectory(path === undefined ? {} : { path }, signal)
+    if (!response.result.ok) throw new DirectoryBrowseError(response.result.error)
+    return response.result.value
+  }
+
+  /**
+   * Create one child directory through the Host's `browse` capability.
+   * @param path - absolute existing parent directory.
+   * @param name - single non-blank path segment.
+   * @returns the created directory's absolute path.
+   */
+  async createDirectory(path: string, name: string): Promise<string> {
+    const response = await this.api.host.createDirectory({ path, name })
+    if (!response.result.ok) throw new DirectoryBrowseError(response.result.error)
+    return response.result.value.path
+  }
+
   /**
    * Open a filesystem path with the Host operating system's default application.
    * @param path - absolute or host-resolvable path.

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

@@ -88,6 +88,18 @@ export class FakeApiClient implements IApiClient {
   onOpenPath: (payload: unknown) => Promise<RpcResponse<{ opened: true }>> =
     () => Promise.resolve(ok({ opened: true as const }))
 
+  onListDirectory: (payload: unknown) => Promise<RpcResponse<{
+    path: string
+    home: string
+    crumbs: { name: string; path: string; hidden: boolean }[]
+    entries: { name: string; path: string; hidden: boolean }[]
+    truncated: boolean
+  }>> =
+    () => Promise.resolve(ok({ path: '/home/fake', home: '/home/fake', crumbs: [{ name: '/', path: '/', hidden: false }], entries: [], truncated: false }))
+
+  onCreateDirectory: (payload: unknown) => Promise<RpcResponse<{ path: string }>> =
+    () => Promise.resolve(ok({ path: '/home/fake/new' }))
+
   private readonly muxConns: StreamConn<MuxFrame>[] = []
   private readonly hostConns: StreamConn<HostFrame>[] = []
 
@@ -109,6 +121,8 @@ export class FakeApiClient implements IApiClient {
   readonly host: IApiClient['host'] = {
     describe: (payload: unknown) => this.record('host.describe', payload, this.onDescribe(payload)),
     pickDirectory: (payload: unknown) => this.record('host.pickDirectory', payload, this.onPickDirectory(payload)),
+    listDirectory: (payload: unknown) => this.record('host.listDirectory', payload, this.onListDirectory(payload)),
+    createDirectory: (payload: unknown) => this.record('host.createDirectory', payload, this.onCreateDirectory(payload)),
     openPath: (payload: unknown) => this.record('host.openPath', payload, this.onOpenPath(payload)),
   }
 

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

@@ -3,7 +3,7 @@ import { describe, expect, it } from 'vitest'
 import type { SessionId, WorkspaceId, WorkspaceView } from '@deepseek-ai/dsh-client-connection/client'
 import { SessionsService } from '../src/client/sessions/service.ts'
 import { WorkspaceManager } from '../src/client/workspaces/manager.ts'
-import { WorkspaceCreateError, WorkspacesService } from '../src/client/workspaces/service.ts'
+import { DirectoryBrowseError, WorkspaceCreateError, WorkspacesService } from '../src/client/workspaces/service.ts'
 import { FakeApiClient, deferred, err, ok } from './fake-api.ts'
 
 const sid = (id: string): SessionId => id as SessionId
@@ -234,6 +234,29 @@ describe('WorkspacesService', () => {
     api.onPickDirectory = () => Promise.resolve(ok({ path: null }))
     await expect(workspaces.pickDirectory()).resolves.toBeNull()
     expect(api.callsOf('host.pickDirectory')).toEqual([{}, {}])
+    api.onPickDirectory = () => Promise.resolve(err({ code: 'internal', message: 'no chooser', details: {} }))
+    await expect(workspaces.pickDirectory()).rejects.toThrow(/no chooser/)
+  })
+
+  it('passes listings and creation through the browse wire, wrapping business failures', async () => {
+    const ctx = new Context()
+    const api = new FakeApiClient()
+    const workspaces = new WorkspacesService(ctx, api, new SessionsService(ctx, api))
+    const listing = { path: '/home/u', home: '/home/u', crumbs: [{ name: '/', path: '/', hidden: false }], entries: [{ name: 'p', path: '/home/u/p', hidden: false }], truncated: false }
+    api.onListDirectory = () => Promise.resolve(ok(listing))
+    await expect(workspaces.listDirectory()).resolves.toEqual(listing)
+    await expect(workspaces.listDirectory('/home/u')).resolves.toEqual(listing)
+    // The optional path is omitted from the payload, not sent as undefined.
+    expect(api.callsOf('host.listDirectory')).toEqual([{}, { path: '/home/u' }])
+    api.onListDirectory = () => Promise.resolve(err({ code: 'directory-unreadable', message: 'denied', details: { path: '/x' } }))
+    const listFailure = workspaces.listDirectory('/x')
+    await expect(listFailure).rejects.toBeInstanceOf(DirectoryBrowseError)
+    await expect(listFailure).rejects.toMatchObject({ rpcError: { code: 'directory-unreadable' } })
+
+    await expect(workspaces.createDirectory('/home/u', 'fresh')).resolves.toBe('/home/fake/new')
+    expect(api.callsOf('host.createDirectory')).toEqual([{ path: '/home/u', name: 'fresh' }])
+    api.onCreateDirectory = () => Promise.resolve(err({ code: 'directory-exists', message: 'taken', details: { path: '/home/u/fresh' } }))
+    await expect(workspaces.createDirectory('/home/u', 'fresh')).rejects.toMatchObject({ rpcError: { code: 'directory-exists' } })
   })
 
   it('opens a filesystem path through the host without local state', async () => {

packages/client/test-runtime/src/workspaces.ts

@@ -1,7 +1,7 @@
 /** Test-owned workspaces face: the renderer standard-kit observable plus recorded actions. */
 import { createSnapshotStore } from '@deepseek-ai/dsh-client-runtime/client'
 import type {
-  IWorkspaces, SessionId, SnapshotStore, WorkspaceId, WorkspaceListState, WorkspaceView,
+  DirectoryListing, IWorkspaces, SessionId, SnapshotStore, WorkspaceId, WorkspaceListState, WorkspaceView,
 } from '@deepseek-ai/dsh-client-runtime/client'
 import { workspaceListState } from './fixtures.ts'
 import type { Stabilizer } from './fixtures.ts'
@@ -109,6 +109,48 @@ export class TestWorkspaces implements IWorkspaces {
     return null
   }
 
+  /**
+   * Browse listing (recorded). The default serves an empty home level; stub
+   * to shape a tree.
+   * @param path - absolute directory to list; absent lists the home level.
+   * @returns the level's listing.
+   */
+  async listDirectory(path?: string, signal?: AbortSignal): Promise<DirectoryListing> {
+    // The signal is recorded and forwarded like the production face passes
+    // it to the wire, so cancellation integration tests can observe or
+    // reject on a superseded scan.
+    this.calls.push({ method: 'listDirectory', args: [path, signal] })
+    const stub = this.stubs.get('listDirectory')
+    if (stub !== undefined) return await (stub(path, signal) as Promise<DirectoryListing>)
+    // The chain runs root-to-target inclusive, per the DirectoryListing
+    // contract — a bare root crumb would mislabel the level in browsers
+    // driven by this double.
+    return {
+      path: '/home/test',
+      home: '/home/test',
+      crumbs: [
+        { name: '/', path: '/', hidden: false },
+        { name: 'home', path: '/home', hidden: false },
+        { name: 'test', path: '/home/test', hidden: false },
+      ],
+      entries: [],
+      truncated: false,
+    }
+  }
+
+  /**
+   * Browse child creation (recorded). The default joins parent and name.
+   * @param path - absolute existing parent directory.
+   * @param name - single path segment.
+   * @returns the created directory's absolute path.
+   */
+  async createDirectory(path: string, name: string): Promise<string> {
+    this.calls.push({ method: 'createDirectory', args: [path, name] })
+    const stub = this.stubs.get('createDirectory')
+    if (stub !== undefined) return await (stub(path, name) as Promise<string>)
+    return `${path}/${name}`
+  }
+
   /**
    * Rename a Workspace (recorded). The default echoes a minimal view.
    * @param workspaceId - target workspace.

packages/client/test-runtime/tests/runtime.spec.tsx

@@ -322,6 +322,32 @@ describe('workspaces', () => {
     expect(stub).toHaveBeenCalledOnce()
     await runtime.dispose()
   })
+
+  it('records the browse calls: listDirectory serves an empty home, createDirectory joins, stubs override', async () => {
+    const runtime = await runtimeWithFrame()
+    // Defaults: an empty home level and parent/name joining.
+    await expect(runtime.workspaces.listDirectory()).resolves.toMatchObject({ path: '/home/test', entries: [] })
+    await expect(runtime.workspaces.listDirectory('/home/test')).resolves.toMatchObject({ path: '/home/test' })
+    await expect(runtime.workspaces.createDirectory('/home/test', 'fresh')).resolves.toBe('/home/test/fresh')
+    // The recorded signal seat mirrors the production face (undefined here;
+    // cancellation tests pass and observe a real one).
+    expect(runtime.workspaces.calls).toEqual([
+      { method: 'listDirectory', args: [undefined, undefined] },
+      { method: 'listDirectory', args: ['/home/test', undefined] },
+      { method: 'createDirectory', args: ['/home/test', 'fresh'] },
+    ])
+    // Stubs replace the defaults like every sibling method.
+    const listing = { path: '/x', home: '/x', crumbs: [], entries: [] }
+    const listStub = vi.fn(() => Promise.resolve(listing as never))
+    runtime.workspaces.stub('listDirectory', listStub)
+    runtime.workspaces.stub('createDirectory', vi.fn(() => Promise.resolve('/x/made' as never)))
+    const scan = new AbortController()
+    await expect(runtime.workspaces.listDirectory('/x', scan.signal)).resolves.toBe(listing)
+    // The stub receives the signal too, like the production face gives the wire.
+    expect(listStub).toHaveBeenLastCalledWith('/x', scan.signal)
+    await expect(runtime.workspaces.createDirectory('/x', 'made')).resolves.toBe('/x/made')
+    await runtime.dispose()
+  })
 })
 
 describe('feature mount and disposal', () => {

packages/client/ui-primitives/src/Modal.tsx

@@ -12,13 +12,16 @@ import css from './Modal.module.css'
  * Render a centered modal over a blurred page mask.
  * @param props.open - whether the dialog is showing.
  * @param props.onClose - Escape or mask click.
- * @param props.title - dialog heading.
+ * @param props.title - dialog heading (aria-label in every mode).
  * @param props.description - optional supporting sentence under the title.
  * @param props.children - body (inputs, etc.).
  * @param props.footer - action row (Cancel / Create).
+ * @param props.headless - render children directly in the card (no default
+ * header/close/body chrome) for dialogs whose figma frame owns its own
+ * header structure; mask, card, Escape, and aria-label remain.
  * @returns null when closed; otherwise the overlay tree.
  */
-export function Modal({ open, onClose, title, description, children, footer, className }: {
+export function Modal({ open, onClose, title, description, children, footer, className, headless = false }: {
   open: boolean
   onClose: () => void
   title: string
@@ -26,6 +29,7 @@ export function Modal({ open, onClose, title, description, children, footer, cla
   children?: ReactNode
   footer?: ReactNode
   className?: string
+  headless?: boolean
 }) {
   useEffect(() => {
     if (!open) return
@@ -47,19 +51,25 @@ export function Modal({ open, onClose, title, description, children, footer, cla
         aria-modal="true"
         aria-label={title}
       >
-        <div className={css.content}>
-          <div className={css.header}>
-            <h2 className={css.title}>{title}</h2>
-            <button type="button" className={css.close} aria-label="Close" onClick={onClose}>
-              <IconCloseOutline16 size={14} />
-            </button>
-          </div>
-          {description !== undefined && description !== '' && (
-            <p className={css.description}>{description}</p>
+        {headless
+          ? children
+          : (
+            <>
+              <div className={css.content}>
+                <div className={css.header}>
+                  <h2 className={css.title}>{title}</h2>
+                  <button type="button" className={css.close} aria-label="Close" onClick={onClose}>
+                    <IconCloseOutline16 size={14} />
+                  </button>
+                </div>
+                {description !== undefined && description !== '' && (
+                  <p className={css.description}>{description}</p>
+                )}
+                {children !== undefined && <div className={css.body}>{children}</div>}
+              </div>
+              {footer !== undefined && <div className={css.footer}>{footer}</div>}
+            </>
           )}
-          {children !== undefined && <div className={css.body}>{children}</div>}
-        </div>
-        {footer !== undefined && <div className={css.footer}>{footer}</div>}
       </div>
     </div>
   )

packages/client/ui-slots/src/deferred.ts

@@ -36,13 +36,22 @@ export interface DeferredRegistration {
  * @param name - target slot name.
  * @param component - the component whose ledger presence marks "registered".
  * @param register - performs the actual registration; returns its disposer.
+ * @param onFailure - owns a registration failure that fires from a LATER
+ * ledger flush (a declaration landing after two providers deferred, say):
+ * the deferral first removes its own subscription, then hands the error
+ * over instead of throwing through the flush — the callback's chance to
+ * roll back sibling deferrals and surface the conflict on a loud channel.
+ * Absent, a late failure rethrows out of the flush.
  * @returns the deferral handle (dispose in the owning effect's disposer).
+ * @throws the immediate registration's failure, after removing the
+ * just-installed subscription — a throwing construction leaves nothing live.
  */
 export function deferRegistration(
   registry: DeferralRegistry,
   name: string,
   component: unknown,
   register: () => () => void,
+  onFailure?: (error: unknown) => void,
 ): DeferredRegistration {
   let dispose: (() => void) | undefined
   const tryRegister = (): void => {
@@ -50,8 +59,24 @@ export function deferRegistration(
     if (registry.entries(name).some(e => e.component === component)) return
     dispose = register()
   }
-  const unsubscribe = registry.subscribe(name, () => { tryRegister() })
-  tryRegister()
+  const unsubscribe = registry.subscribe(name, () => {
+    try {
+      tryRegister()
+    } catch (error) {
+      unsubscribe()
+      if (onFailure === undefined) throw error
+      onFailure(error)
+    }
+  })
+  try {
+    tryRegister()
+  } catch (error) {
+    // A synchronous registration failure (the declared slot is already
+    // occupied) must not leave the just-installed subscription behind: the
+    // caller receives no handle to dispose it through.
+    unsubscribe()
+    throw error
+  }
   return {
     refresh() {
       dispose?.()
@@ -64,3 +89,40 @@ export function deferRegistration(
     },
   }
 }
+
+/**
+ * Defer ONE occupant into several holes as a unit. Construction that throws
+ * partway (a declared hole already occupied registers synchronously) rolls
+ * every earlier deferral back before rethrowing; a failure surfacing from a
+ * LATER ledger flush (holes declared after rival providers activated) rolls
+ * the whole group back the same way and re-raises the wrapped error on the
+ * global channel the boot's fail-loud handler owns — never a throw through
+ * the slot flush, never partial occupancy from the group's owner.
+ * @param registry - the slot registry face.
+ * @param names - the target holes (one registration per name).
+ * @param component - the occupant whose ledger presence marks "registered".
+ * @param register - performs one hole's registration; returns its disposer.
+ * @returns the group handle (dispose in the owning effect's disposer).
+ * @throws the immediate registration's failure, after rolling the group back.
+ */
+export function deferGroupRegistration<K extends string>(
+  registry: DeferralRegistry,
+  names: readonly K[],
+  component: unknown,
+  register: (name: K) => () => void,
+): { dispose: () => void } {
+  const deferred: DeferredRegistration[] = []
+  const lateFailure = (error: unknown): void => {
+    for (const entry of deferred) entry.dispose()
+    queueMicrotask(() => { throw error instanceof Error ? error : new Error(String(error)) })
+  }
+  try {
+    for (const name of names) {
+      deferred.push(deferRegistration(registry, name, component, () => register(name), lateFailure))
+    }
+  } catch (error) {
+    for (const entry of deferred) entry.dispose()
+    throw error
+  }
+  return { dispose: () => { for (const entry of deferred) entry.dispose() } }
+}

packages/client/ui-slots/tests/deferred.spec.ts

@@ -0,0 +1,126 @@
+// deferRegistration lifecycle: declaration-aware registration, HMR
+// re-registration, and — the failure contract — no subscription survives a
+// construction that throws synchronously (an already-occupied single slot).
+import { describe, expect, it, vi } from 'vitest'
+import { deferGroupRegistration, deferRegistration, SlotCore } from '@deepseek-ai/dsh-client-ui-slots'
+
+// Shares the merges declared by core.spec.ts (same program); reuse its keys.
+const HOLE = 'test.single' as const
+
+function declared(): SlotCore {
+  const core = new SlotCore()
+  core.register({ name: 'root', children: { [HOLE]: { kind: 'single', scope: 'root' } } } as never, (() => null) as never)
+  return core
+}
+
+describe('deferRegistration', () => {
+  it('registers immediately under an existing declaration and disposes cleanly', () => {
+    const core = declared()
+    const component = (): null => null
+    const handle = deferRegistration(core, HOLE, component, () =>
+      core.register({ name: HOLE } as never, component as never))
+    expect(core.entries(HOLE)).toHaveLength(1)
+    handle.dispose()
+    expect(core.entries(HOLE)).toHaveLength(0)
+  })
+
+  it('hands a late registration failure to onFailure after unsubscribing itself', async () => {
+    const core = new SlotCore()
+    const component = (): null => null
+    const foreign = (): null => null
+    const failures: unknown[] = []
+    // Nothing is declared yet: the deferral just subscribes and waits.
+    const register = vi.fn(() => core.register({ name: HOLE } as never, component as never))
+    deferRegistration(core, HOLE, component, register, (error) => { failures.push(error) })
+    // The declaration lands with a foreign occupant racing in first: the
+    // deferral's flush-time attempt fails, unsubscribes itself, and reports
+    // through onFailure instead of throwing out of the flush.
+    core.register({ name: 'root', children: { [HOLE]: { kind: 'single', scope: 'root' } } } as never, (() => null) as never)
+    const disposeForeign = core.register({ name: HOLE } as never, foreign as never)
+    await Promise.resolve()
+    expect(failures.map(String).join('')).toContain('already has a registration')
+    // Unsubscribed: freeing the hole must not resurrect the loser.
+    disposeForeign()
+    await Promise.resolve()
+    expect(core.entries(HOLE)).toHaveLength(0)
+  })
+
+  it('drops its subscription when the immediate registration throws', async () => {
+    const core = declared()
+    const foreign = (): null => null
+    const disposeForeign = core.register({ name: HOLE } as never, foreign as never)
+    const component = (): null => null
+    const register = vi.fn(() => core.register({ name: HOLE } as never, component as never))
+    // The single hole is occupied: the immediate attempt throws out of the
+    // constructor, and the caller never receives a handle to dispose.
+    expect(() => deferRegistration(core, HOLE, component, register)).toThrow(/already has a registration/)
+    expect(register).toHaveBeenCalledOnce()
+    // The subscription rolled back with it: freeing the hole flushes a
+    // notification that must not resurrect the failed registration.
+    disposeForeign()
+    await Promise.resolve()
+    expect(register).toHaveBeenCalledOnce()
+    expect(core.entries(HOLE)).toHaveLength(0)
+  })
+})
+
+describe('deferGroupRegistration', () => {
+  const HOLES = ['test.single', 'test.grandchild'] as const
+
+  function declaredPair(): SlotCore {
+    const core = new SlotCore()
+    core.register({
+      name: 'root',
+      children: Object.fromEntries(HOLES.map(name => [name, { kind: 'single', scope: 'root' }])),
+    } as never, (() => null) as never)
+    return core
+  }
+
+  it('registers the whole group and disposes it as a unit', () => {
+    const core = declaredPair()
+    const component = (): null => null
+    const group = deferGroupRegistration(core, HOLES, component, name =>
+      core.register({ name } as never, component as never))
+    for (const name of HOLES) expect(core.entries(name)).toHaveLength(1)
+    group.dispose()
+    for (const name of HOLES) expect(core.entries(name)).toHaveLength(0)
+  })
+
+  it('rolls the group back when construction fails partway', () => {
+    const core = declaredPair()
+    const component = (): null => null
+    core.register({ name: HOLES[1] } as never, (() => null) as never)
+    expect(() => deferGroupRegistration(core, HOLES, component, name =>
+      core.register({ name } as never, component as never))).toThrow(/already has a registration/)
+    // The first hole's registration and subscription rolled back with it.
+    expect(core.entries(HOLES[0])).toHaveLength(0)
+  })
+
+  it('rolls the group back and re-raises loudly on a late conflict', async () => {
+    const core = new SlotCore()
+    const component = (): null => null
+    const failures: unknown[] = []
+    const onLoud = (reason: unknown): void => { failures.push(reason) }
+    process.on('uncaughtException', onLoud)
+    try {
+      const group = deferGroupRegistration(core, HOLES, component, name =>
+        core.register({ name } as never, component as never))
+      // Declaration lands with a rival racing in ahead of the flush.
+      core.register({
+        name: 'root',
+        children: Object.fromEntries(HOLES.map(name => [name, { kind: 'single', scope: 'root' }])),
+      } as never, (() => null) as never)
+      core.register({ name: HOLES[0] } as never, (() => null) as never)
+      core.register({ name: HOLES[1] } as never, (() => null) as never)
+      await new Promise(resolve => setTimeout(resolve, 20))
+      expect(failures.map(String).join('')).toContain('already has a registration')
+      // No partial occupancy from the group's owner survives.
+      for (const name of HOLES) {
+        expect(core.entries(name).filter(entry => entry.component === component)).toHaveLength(0)
+      }
+      group.dispose()
+    } finally {
+      process.off('uncaughtException', onLoud)
+    }
+  })
+})

packages/client/ui-workspace/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/ui-workspace/README.md
-README.md: edd6c2f9373d97832def86bb44658d7c1c68dae9
-README.zh.md: f7b73dde953d4294d4d157f479fe932adf1a29c4
+README.md: 8acf819121b46512d38b39ff858bb2bf797cfe96
+README.zh.md: e97d93f7e38d00af91b43f0df9fb0e3b17ae8ed5

packages/client/ui-workspace/README.md

@@ -4,7 +4,7 @@ English | [中文](README.zh.md)
 
 Shared Workspace picker plugin. `WorkspaceBrowser` is registered into the sidebar's `sidebar.workspaces` slot and `WorkspacePicker` into the page-local Session Intent hero's `conversation.hero.workspace` slot, so both surfaces use the same menu and creation flow.
 
-The picker lists real Host Workspace entities through the global `useWorkspaces` hook. Selecting a Workspace invokes the slot owner's `onPick` callback to retarget the frontend Session object. The flat **Open local folder...** action delegates to the Host's native single-directory picker, adopts a returned path through the object layer, and selects the committed Workspace only after its list projection has refreshed; cancellation is silent, and errors remain retryable. **Create a new workspace** retains the name dialog and disables names already present in that list, while the Host remains authoritative for concurrent or non-UI callers. The runtime Session and Workspace services own materialization. The Workspace row's Delete action opens a confirmation that states the retention boundary, blocks duplicate submission, and keeps failures open; success removes the group while its Sessions remain under Ungrouped.
+The picker lists real Host Workspace entities through the global `useWorkspaces` hook. Selecting a Workspace invokes the slot owner's `onPick` callback to retarget the frontend Session object. Each registration declares a **directory-flow child hole** (`single` kind: `conversation.hero.workspace.directoryFlow` / `sidebar.workspaces.directoryFlow`) that the composed picker package's client half fills with its picking interaction — the [`-native`](../../host/directory-picker-native/README.md) backend's renderless OS-chooser driver today, an in-app browsing dialog under a `-browse` composition. The flat **Open local folder...** action renders only while the surface's hole is occupied (occupancy read per menu render; an empty hole means the composition has no picking affordance — the seam's documented no-flow default). This package owns the trigger and the adoption: the occupant reports one picked path per open through the hole's owner conversation (`open`/`busy`/`onPicked`/`onCancel`/`onError`), and the owner adopts it through the object layer, selecting the committed Workspace only after its list projection has refreshed; cancellation is silent, and errors land in the retryable folder dialog whose **Choose again** reopens the flow. **Create a new workspace** retains the name dialog and disables names already present in that list, while the Host remains authoritative for concurrent or non-UI callers. The runtime Session and Workspace services own materialization. The Workspace row's Delete action opens a confirmation that states the retention boundary, blocks duplicate submission, and keeps failures open; success removes the group while its Sessions remain under Ungrouped.
 
 Both target slots are declared by other plugins, so `apply` registers through declaration-aware deferral and re-registers after a declaring slot is restored.
 
@@ -19,4 +19,4 @@ None; this package neither assembles nor sends a provider request.
 ## Known Limitations and Deferred Work
 
 - **No Session deletion control** — the existing Session menu row remains visual-only; Workspace registration deletion does not delete Sessions.
-- **Native folder selection depends on the local Host carrier** — fixture-only or remote browser deployments cannot open a local operating-system dialog; platform failures are shown in a retryable modal.
+- **Native folder selection depends on the local Host carrier** — under the `-native` composition, fixture-only or remote browser deployments cannot open a local operating-system dialog; platform failures are shown in a retryable modal. Remote-capable picking is the `-browse` composition's in-app flow.

packages/client/ui-workspace/README.zh.md

@@ -4,7 +4,7 @@
 
 共享 Workspace 选择器插件。`WorkspaceBrowser` 注册到侧边栏的 `sidebar.workspaces` slot，`WorkspacePicker` 注册到页面局部 Session Intent 主视觉区的 `conversation.hero.workspace` slot，因此两个表层使用同一菜单和创建流程。
 
-该选择器通过全局 `useWorkspaces` hook 列出真实的 Host Workspace 实体。选择 Workspace 会调用 slot owner 的 `onPick` 回调，重新定位前端 Session 对象。平铺显示的 **打开本地文件夹…** 操作会委托 Host 的原生单目录选择器，通过对象层接纳返回的路径，并等待 Workspace 列表投影刷新后才选中已提交的 Workspace；取消操作不会显示提示，发生错误后仍可重试。**创建新工作区** 操作保留名称对话框，并禁用列表中已有的名称，而 Host 对并发或非 UI 调用方仍具有最终决定权。运行时 Session 与 Workspace 服务负责物化。Workspace 行内的 Delete 操作会打开确认框，说明保留边界、阻止重复提交，并在失败时保持打开；成功后，该分组会被移除，其 Session 则留在 Ungrouped 下。
+该选择器通过全局 `useWorkspaces` hook 列出真实的 Host Workspace 实体。选择 Workspace 会调用 slot owner 的 `onPick` 回调，重新定位前端 Session 对象。每个注册各自声明一个**目录流子洞**（`single` kind：`conversation.hero.workspace.directoryFlow`／`sidebar.workspaces.directoryFlow`），由组合的选择器包 client half 填入其选取交互——今天是 [`-native`](../../host/directory-picker-native/README.md) 后端的无渲染 OS 选择器驱动，`-browse` 组合下则是应用内浏览对话框。平铺显示的 **打开本地文件夹…** 操作仅在本表层的洞被占用时渲染（每次菜单渲染读取占用状态；洞为空意味着该组合没有选目录能力——seam 文档化的无流程默认行为）。本包持有触发与接纳：占用者经洞的 owner 会话（`open`/`busy`/`onPicked`/`onCancel`/`onError`）每次打开上报一个所选路径，owner 通过对象层接纳它，并等待 Workspace 列表投影刷新后才选中已提交的 Workspace；取消操作不会显示提示，错误落入可重试的文件夹对话框，其 **重新选择** 会重新打开流程。**创建新工作区** 操作保留名称对话框，并禁用列表中已有的名称，而 Host 对并发或非 UI 调用方仍具有最终决定权。运行时 Session 与 Workspace 服务负责物化。Workspace 行内的 Delete 操作会打开确认框，说明保留边界、阻止重复提交，并在失败时保持打开；成功后，该分组会被移除，其 Session 则留在 Ungrouped 下。
 
 两个目标 slot 都由其他插件声明，因此 `apply` 通过声明感知的延迟机制完成注册，并在声明该 slot 的插件恢复后重新注册。
 
@@ -19,4 +19,4 @@
 ## 已知限制与暂缓事项
 
 - **没有 Session 删除控件**：现有 Session 菜单行仍仅提供视觉效果；删除 Workspace 注册记录不会删除 Session。
-- **原生文件夹选择依赖本地 Host 载体**：仅使用 fixture（测试前置数据）的部署或远程浏览器部署无法打开本地操作系统对话框；模态框会显示平台故障，并允许重试。
+- **原生文件夹选择依赖本地 Host 载体**：在 `-native` 组合下，仅使用 fixture（测试前置数据）的部署或远程浏览器部署无法打开本地操作系统对话框；模态框会显示平台故障，并允许重试。可远程的选取是 `-browse` 组合的应用内流程。

packages/client/ui-workspace/src/client/WorkspaceBrowser.tsx

@@ -253,7 +253,8 @@ export function WorkspaceBrowser({
   deleteWorkspace,
   insertSessionBefore,
   createWorkspace,
-  pickDirectory,
+  useDirectoryFlow,
+  renderSlot,
 }: WorkspaceBrowserProps) {
   const workspaces = useWorkspaces(state => state.items)
   const groupBy = useStore(s => s.groupBy)
@@ -371,7 +372,8 @@ export function WorkspaceBrowser({
           anchorRef={wsPlusRef}
           useWorkspaces={useWorkspaces}
           createWorkspace={createWorkspace}
-          pickDirectory={pickDirectory}
+          useDirectoryFlow={useDirectoryFlow}
+          renderDirectoryFlow={owner => renderSlot('sidebar.workspaces.directoryFlow', owner)}
           createOnly
           side="right"
           onPick={(workspaceId) => {

packages/client/ui-workspace/src/client/WorkspacePicker.tsx

@@ -2,10 +2,12 @@
  * Workspace pick/create flow. WorkspaceCreateFlow is the reusable core
  * (menu + path/create dialogs) consumed directly by WorkspaceBrowser (same
  * package) and wrapped by WorkspacePicker for the conversation empty-state
- * slot registration.
+ * slot registration. Directory picking itself lives in the composed flow
+ * package's slot occupant (see the contract module doc): this core only
+ * opens the flow, adopts the picked path, and owns the error surface.
  */
-import type { RefObject } from 'react'
-import { useCallback, useRef, useState } from 'react'
+import type { ReactNode, RefObject } from 'react'
+import { useCallback, useEffect, useRef, useState } from 'react'
 import {
   Button, IconFolderClose16, IconPlusOutline16, Menu, Modal, type MenuEntry,
 } from '@deepseek-ai/dsh-client-ui-primitives'
@@ -13,7 +15,8 @@ import {
   WorkspaceCreateError,
   type WorkspaceId, type WorkspaceListState, type WorkspaceView,
 } from '@deepseek-ai/dsh-client-runtime/client'
-import type { WorkspacePickerProps } from './contract/slots.ts'
+import type { SnapshotSelectorHook } from '@deepseek-ai/dsh-client-ui-slots'
+import type { DirectoryFlowOwnerProps, WorkspacePickerProps } from './contract/slots.ts'
 import css from './WorkspacePicker.module.css'
 
 const OPEN_LOCAL_FOLDER = '::open-local-folder'
@@ -31,8 +34,10 @@ export interface WorkspaceCreateFlowProps {
   useWorkspaces: <S>(selector: (state: WorkspaceListState) => S) => S
   /** Create or adopt a real Host Workspace. */
   createWorkspace: (input: { name: string } | { path: string }) => Promise<WorkspaceView>
-  /** Open the Host's native single-directory picker. */
-  pickDirectory: () => Promise<string | null>
+  /** Bound occupancy selector hook for this surface's directory-flow hole (empty hides the local-folder entry). */
+  useDirectoryFlow: SnapshotSelectorHook<boolean>
+  /** Render this surface's directory-flow hole with the owner conversation (the entry's narrowed renderSlot). */
+  renderDirectoryFlow: (owner: DirectoryFlowOwnerProps) => ReactNode
   /** A real Workspace was picked or created. */
   onPick: (workspaceId: WorkspaceId) => void
   /** Close the popover (outside click / Escape / post-pick). */
@@ -55,7 +60,8 @@ export function WorkspaceCreateFlow({
   anchorRef,
   useWorkspaces,
   createWorkspace,
-  pickDirectory,
+  useDirectoryFlow,
+  renderDirectoryFlow,
   onPick,
   onClose,
   createOnly = false,
@@ -72,16 +78,37 @@ export function WorkspaceCreateFlow({
   const [workspaceName, setWorkspaceName] = useState('')
   const [creating, setCreating] = useState(false)
   const [modalError, setModalError] = useState<string | null>(null)
+  const [flowOpen, setFlowOpen] = useState(false)
   const [pickingFolder, setPickingFolder] = useState(false)
   const [folderConflict, setFolderConflict] = useState(false)
   const composingRef = useRef(false)
+  // One picking interaction at a time: while the flow is open (native chooser
+  // pending, browse dialog up) or its pick is being adopted, every other
+  // menu action stays disabled — a late outcome must not race a concurrent
+  // selection or creation.
+  const flowBusy = flowOpen || pickingFolder
   const normalizedWorkspaceName = workspaceName.trim()
   const duplicateWorkspaceName = !creating && normalizedWorkspaceName !== ''
     && workspaces.some(workspace => workspace.title === normalizedWorkspaceName)
 
+  // The occupied hole gates the picking affordance: with no composed flow the
+  // entry simply is not there (the seam's documented no-flow default). The
+  // framework-bound hook keeps occupancy live: flow plugins activate (and
+  // HMR-reload) independently of this menu's renders.
+  const flowAvailable = useDirectoryFlow(occupied => occupied)
+  // An occupant that unloads mid-interaction leaves nobody to cancel: an
+  // open flow over an empty hole withdraws so the menu actions come back.
+  // flowOpen is a dependency because the flow can also OPEN over an already
+  // empty hole (Choose again after the occupant unloaded with the error
+  // dialog up) — that transition must snap back too, not just occupancy loss.
+  useEffect(() => {
+    if (flowOpen && !flowAvailable) setFlowOpen(false)
+  }, [flowOpen, flowAvailable])
   const createEntries: MenuEntry[] = [
-    { id: OPEN_LOCAL_FOLDER, label: 'Open local folder…', icon: <IconFolderClose16 size={16} />, disabled: pickingFolder },
-    { id: CREATE_NEW, label: 'Create a new workspace', icon: <IconPlusOutline16 size={16} />, disabled: pickingFolder },
+    ...(flowAvailable
+      ? [{ id: OPEN_LOCAL_FOLDER, label: 'Open local folder…', icon: <IconFolderClose16 size={16} />, disabled: flowBusy }]
+      : []),
+    { id: CREATE_NEW, label: 'Create a new workspace', icon: <IconPlusOutline16 size={16} />, disabled: flowBusy },
   ]
   // With workspaces listed, the create actions pin below the scroll region
   // (divider + always visible); otherwise they ARE the menu.
@@ -91,7 +118,7 @@ export function WorkspaceCreateFlow({
       id: workspace.workspaceId,
       label: workspace.title,
       icon: <IconFolderClose16 size={16} />,
-      disabled: pickingFolder,
+      disabled: flowBusy,
     }))
     : createEntries
 
@@ -101,15 +128,10 @@ export function WorkspaceCreateFlow({
     setModalError(null)
   }
 
-  const openLocalFolder = (): void => {
-    onClose()
-    setModalKind(null)
-    setModalError(null)
-    setFolderConflict(false)
-    setPickingFolder(true)
-    void pickDirectory().then(async (path) => {
-      if (path === null) return
-      const workspace = await createWorkspace({ path })
+  /** Adopt a picked directory; failures land in the folder-error dialog (Choose again reopens the flow). */
+  const adoptDirectory = (path: string): Promise<void> =>
+    createWorkspace({ path }).then((workspace) => {
+      setFlowOpen(false)
       onPick(workspace.workspaceId)
     }).catch((reason: unknown) => {
       setFolderConflict(
@@ -117,8 +139,33 @@ export function WorkspaceCreateFlow({
         && reason.rpcError.code === 'workspace-name-conflict',
       )
       setModalError(reason instanceof Error ? reason.message : String(reason))
+      setFlowOpen(false)
       setModalKind('folder-error')
-    }).finally(() => { setPickingFolder(false) })
+    })
+
+  const openLocalFolder = (): void => {
+    onClose()
+    setModalKind(null)
+    setModalError(null)
+    setFolderConflict(false)
+    setFlowOpen(true)
+  }
+
+  /** Owner side of the flow conversation: adopt keeps the flow open (busy) until the Host answers. */
+  const flowOwner: DirectoryFlowOwnerProps = {
+    open: flowOpen,
+    busy: pickingFolder,
+    onPicked: (path) => {
+      setPickingFolder(true)
+      void adoptDirectory(path).finally(() => { setPickingFolder(false) })
+    },
+    onCancel: () => { setFlowOpen(false) },
+    onError: (message) => {
+      setFlowOpen(false)
+      setFolderConflict(false)
+      setModalError(message)
+      setModalKind('folder-error')
+    },
   }
 
   const handleSelect = (id: string): void => {
@@ -172,6 +219,7 @@ export function WorkspaceCreateFlow({
         getAnchorRect={getAnchorRect}
       />
       {open && workspaceSnapshot.phase === 'pending' && <div className={css.menuStatus} role="status">Loading workspaces…</div>}
+      {renderDirectoryFlow(flowOwner)}
       <Modal
         open={modalKind === 'folder-error'}
         onClose={closeModal}
@@ -179,7 +227,9 @@ export function WorkspaceCreateFlow({
         footer={(
           <>
             <Button variant="outline" className={css.modalAction} onClick={closeModal}>Cancel</Button>
-            <Button variant="primary" className={css.modalAction} onClick={openLocalFolder}>Choose again</Button>
+            {/* Retrying needs an occupant to serve the flow; without one the
+              * button would open a flow nobody can answer or cancel. */}
+            <Button variant="primary" className={css.modalAction} disabled={!flowAvailable} onClick={openLocalFolder}>Choose again</Button>
           </>
         )}
       >
@@ -249,7 +299,8 @@ export function WorkspacePicker({
   onPick,
   onClose,
   createWorkspace,
-  pickDirectory,
+  useDirectoryFlow,
+  renderSlot,
 }: WorkspacePickerProps) {
   return (
     <WorkspaceCreateFlow
@@ -257,7 +308,8 @@ export function WorkspacePicker({
       anchorRef={anchorRef}
       useWorkspaces={useWorkspaces}
       createWorkspace={createWorkspace}
-      pickDirectory={pickDirectory}
+      useDirectoryFlow={useDirectoryFlow}
+      renderDirectoryFlow={owner => renderSlot('conversation.hero.workspace.directoryFlow', owner)}
       selectedId={selectedId}
       onPick={onPick}
       onClose={onClose}

packages/client/ui-workspace/src/client/contract/slots.ts

@@ -7,8 +7,19 @@
  *   consumes the shell's two-fact owner share (wide / expandSidebar).
  * - WorkspacePicker fills the conversation empty-state hole (menu +
  *   create dialogs shared with the browser).
+ *
+ * Each registration also declares one **directory-flow hole** (`single`
+ * kind): the slot a composed picker package's client half fills with its
+ * picking interaction — a renderless native-chooser driver or an in-app
+ * browsing dialog. ui-workspace owns the trigger (the "Open local folder…"
+ * menu entry, shown only while the hole is occupied) and the adoption
+ * semantics (`createWorkspace({ path })`, the conflict/error dialog, Choose
+ * again); the occupant owns everything between `open` and the picked path.
+ * Two holes exist because the two menu surfaces are independent slot entries
+ * and a hole has exactly one declaring entry — they carry the same owner
+ * contract and the same occupant.
  */
-import type { PropsRuntime, PropsStore } from '@deepseek-ai/dsh-client-ui-slots'
+import type { HostObservable, PropsRenderSlots, PropsRuntime, PropsStore, SnapshotSelectorHook } from '@deepseek-ai/dsh-client-ui-slots'
 // Type-only: pull the owner SlotMap merges into programs that resolve the
 // runtime shares below.
 import type {} from '@deepseek-ai/dsh-client-ui-sidebar/client'
@@ -16,12 +27,64 @@ import type {} from '@deepseek-ai/dsh-client-ui-conversation/client'
 import type { SessionId, WorkspaceId, WorkspaceView } from '@deepseek-ai/dsh-client-runtime/client'
 import type { createWorkspaceViewStore } from '../stores.ts'
 
+/**
+ * Owner share of the directory-flow holes: the complete conversation between
+ * the trigger surface and the picking interaction. The occupant reads `open`
+ * to run/render its interaction and reports exactly one outcome per open.
+ */
+export interface DirectoryFlowOwnerProps {
+  /** True while a picking interaction is requested; flipping back to false withdraws the request. */
+  open: boolean
+  /** True while the owner adopts a picked path (`createWorkspace` in flight); occupants disable their commit affordances. */
+  busy: boolean
+  /** The operator picked a directory (absolute host path); the owner adopts it. */
+  onPicked: (path: string) => void
+  /** The operator dismissed the interaction; the owner just closes the flow. */
+  onCancel: () => void
+  /** The interaction itself failed (chooser missing, listing denied); the owner shows its error surface. */
+  onError: (message: string) => void
+}
+
+declare module '@deepseek-ai/dsh-client-ui-slots' {
+  interface SlotMap {
+    /** Directory-flow hole under the conversation empty-state picker (declared by the WorkspacePicker entry). */
+    'conversation.hero.workspace.directoryFlow': { kind: 'single'; scope: 'root'; owner: DirectoryFlowOwnerProps }
+    /** Directory-flow hole under the sidebar browsing region (declared by the WorkspaceBrowser entry). */
+    'sidebar.workspaces.directoryFlow': { kind: 'single'; scope: 'root'; owner: DirectoryFlowOwnerProps }
+  }
+}
+
+/** The two directory-flow holes; a flow package's client half registers its one component into both. */
+export type DirectoryFlowSlotName =
+  | 'conversation.hero.workspace.directoryFlow'
+  | 'sidebar.workspaces.directoryFlow'
+
+/**
+ * Directory-picking share both trigger surfaces consume. Occupancy rides the
+ * inject face's reserved `hooks` compartment: the renderer binds the source
+ * into the `useDirectoryFlow` selector hook, so an empty hole hides the
+ * "Open local folder…" entry reactively and the surface withdraws an open
+ * flow whose occupant unloaded mid-interaction (nobody is left to cancel).
+ */
+export type DirectoryPickingInjected = {
+  hooks: {
+    /** True while this surface's directory-flow hole is occupied. */
+    directoryFlow: HostObservable<boolean>
+  }
+}
+
+/** Component-side view of the picking share: the bound occupancy selector hook. */
+export type DirectoryPickingHooks = {
+  /** Selector hook over this surface's directory-flow occupancy. */
+  useDirectoryFlow: SnapshotSelectorHook<boolean>
+}
+
 /**
  * Browser-private injected share (arrives via the register inject factory).
  * Data reads use the global framework hooks; these are the Host actions the
  * browsing region drives.
  */
-export type WorkspaceBrowserInjected = {
+export type WorkspaceBrowserInjected = DirectoryPickingInjected & {
   /**
    * Start a New Session in a Workspace: reuse-or-create its blank session
    * and open it; with no workspace, clear the selection into the New Session
@@ -42,26 +105,24 @@ export type WorkspaceBrowserInjected = {
   insertSessionBefore: (workspaceId: WorkspaceId, sessionId: SessionId, beforeSessionId?: SessionId) => Promise<void>
   /** Explicitly create or adopt a real Workspace before targeting a Session. */
   createWorkspace: (input: { name: string } | { path: string }) => Promise<WorkspaceView>
-  /** Ask the local Host to open its native single-directory picker. */
-  pickDirectory: () => Promise<string | null>
 }
 
 /** Full browser props: shell owner share + viewing store + injected actions. */
 export type WorkspaceBrowserProps =
   PropsRuntime<'sidebar.workspaces'>
+  & PropsRenderSlots<'sidebar.workspaces.directoryFlow'>
   & PropsStore<ReturnType<typeof createWorkspaceViewStore>>
-  & WorkspaceBrowserInjected
+  & Omit<WorkspaceBrowserInjected, 'hooks'>
+  & DirectoryPickingHooks
 
 /**
  * Picker-private injected share. Pick semantics remain in the owner's onPick
  * callback; this callback creates only the real Host Workspace. A type alias
  * supplies the implicit index signature required by the registry.
  */
-export type WorkspacePickerInjected = {
+export type WorkspacePickerInjected = DirectoryPickingInjected & {
   /** Explicitly create or adopt a real Workspace before targeting a Session. */
   createWorkspace: (input: { name: string } | { path: string }) => Promise<WorkspaceView>
-  /** Ask the local Host to open its native single-directory picker. */
-  pickDirectory: () => Promise<string | null>
 }
 
 /**
@@ -70,4 +131,7 @@ export type WorkspacePickerInjected = {
  * currency, so one composed type serves both registrations.
  */
 export type WorkspacePickerProps =
-  PropsRuntime<'conversation.hero.workspace'> & WorkspacePickerInjected
+  PropsRuntime<'conversation.hero.workspace'>
+  & PropsRenderSlots<'conversation.hero.workspace.directoryFlow'>
+  & Omit<WorkspacePickerInjected, 'hooks'>
+  & DirectoryPickingHooks

packages/client/ui-workspace/src/client/index.ts

@@ -3,9 +3,13 @@
  * the sidebar shell's `sidebar.workspaces` hole (the whole browsing region),
  * and WorkspacePicker fills the conversation hero's picker hole
  * (`conversation.hero.workspace` — both hero forms). Both read real Host
- * Workspaces through the global useWorkspaces hook. Export discipline:
+ * Workspaces through the global useWorkspaces hook, and each declares its
+ * own `single` directory-flow child hole for the composed picker package's
+ * client half (see the contract module doc). Export discipline:
  * packages/client/AGENTS.md.
  */
+import { deferRegistration } from '@deepseek-ai/dsh-client-ui-slots'
+import type { HostObservable } from '@deepseek-ai/dsh-client-ui-slots'
 import type { ClientContext } from '@deepseek-ai/dsh-client-runtime/client'
 import type { WorkspaceBrowserInjected, WorkspacePickerInjected } from './contract/slots.ts'
 import { createWorkspaceViewStore } from './stores.ts'
@@ -13,6 +17,7 @@ import { WorkspaceBrowser } from './WorkspaceBrowser.tsx'
 import { WorkspacePicker } from './WorkspacePicker.tsx'
 
 export type {
+  DirectoryFlowOwnerProps, DirectoryFlowSlotName, DirectoryPickingHooks, DirectoryPickingInjected,
   WorkspaceBrowserInjected, WorkspaceBrowserProps, WorkspacePickerInjected, WorkspacePickerProps,
 } from './contract/slots.ts'
 
@@ -33,6 +38,14 @@ export const inject = ['slots', 'sessions', 'workspaces']
  * @param ctx - client root context.
  */
 export function apply(ctx: ClientContext): void {
+  // Stable per-surface occupancy sources (the renderer's hook cache keys by
+  // source identity): true while the surface's directory-flow hole is filled.
+  const flowSource = (hole: 'sidebar.workspaces.directoryFlow' | 'conversation.hero.workspace.directoryFlow'): HostObservable<boolean> => ({
+    getSnapshot: () => ctx.slots.entries(hole).length > 0,
+    subscribe: listener => ctx.slots.subscribe(hole, listener),
+  })
+  const browserFlowSource = flowSource('sidebar.workspaces.directoryFlow')
+  const pickerFlowSource = flowSource('conversation.hero.workspace.directoryFlow')
   const browserInjected = (): WorkspaceBrowserInjected => ({
     // Explicit group actions keep their target; unscoped New Session rides
     // the runtime's shared action (recent-Workspace projection inside).
@@ -44,48 +57,40 @@ export function apply(ctx: ClientContext): void {
       await ctx.workspaces.insertSessionBefore(workspaceId, sessionId, beforeSessionId)
     },
     createWorkspace: input => ctx.workspaces.create(input),
-    pickDirectory: () => ctx.workspaces.pickDirectory(),
+    hooks: { directoryFlow: browserFlowSource },
   })
   const pickerInjected = (): WorkspacePickerInjected => ({
     createWorkspace: input => ctx.workspaces.create(input),
-    pickDirectory: () => ctx.workspaces.pickDirectory(),
+    hooks: { directoryFlow: pickerFlowSource },
   })
-  // Declaration-aware registration: each owner's declaring apply may activate
-  // after this one (entry activation order is unconstrained), and a register
-  // into an undeclared slot throws. Register once the declaration is on the
-  // ledger; the subscription also re-registers after an HMR collapse
-  // re-declares the slot (the cascade disposed our entry with it).
+  // Declaration-aware registration (deferRegistration): each owner's
+  // declaring apply may activate after this one, and a register into an
+  // undeclared slot throws; the deferral also re-registers after an HMR
+  // collapse re-declares the slot. Each registration declares its own
+  // directory-flow child hole in the same call (declaration = render
+  // authorization, one table).
   ctx.effect(() => {
-    const registrations = [
-      {
-        name: 'sidebar.workspaces' as const,
-        component: WorkspaceBrowser,
-        register: () => ctx.slots.register(
-          { name: 'sidebar.workspaces', store: createWorkspaceViewStore(), inject: browserInjected },
+    const deferred = [
+      deferRegistration(ctx.slots, 'sidebar.workspaces', WorkspaceBrowser, () =>
+        ctx.slots.register(
+          {
+            name: 'sidebar.workspaces',
+            children: { 'sidebar.workspaces.directoryFlow': { kind: 'single', scope: 'root' } },
+            store: createWorkspaceViewStore(),
+            inject: browserInjected,
+          },
           WorkspaceBrowser,
-        ),
-      },
-      {
-        name: 'conversation.hero.workspace' as const,
-        component: WorkspacePicker,
-        register: () => ctx.slots.register(
-          { name: 'conversation.hero.workspace', inject: pickerInjected },
+        )),
+      deferRegistration(ctx.slots, 'conversation.hero.workspace', WorkspacePicker, () =>
+        ctx.slots.register(
+          {
+            name: 'conversation.hero.workspace',
+            children: { 'conversation.hero.workspace.directoryFlow': { kind: 'single', scope: 'root' } },
+            inject: pickerInjected,
+          },
           WorkspacePicker,
-        ),
-      },
+        )),
     ]
-    const disposers = new Map<string, () => void>()
-    const tryRegister = (entry: (typeof registrations)[number]): void => {
-      if (ctx.slots.spec(entry.name) === undefined) return
-      if (ctx.slots.entries(entry.name).some(e => e.component === entry.component)) return
-      disposers.set(entry.name, entry.register())
-    }
-    const unsubscribers = registrations.map(entry =>
-      ctx.slots.subscribe(entry.name, () => { tryRegister(entry) }))
-    for (const entry of registrations) tryRegister(entry)
-    return () => {
-      for (const unsubscribe of unsubscribers) unsubscribe()
-      for (const dispose of disposers.values()) dispose()
-    }
+    return () => { for (const entry of deferred) entry.dispose() }
   }, 'ui-workspace: browser + picker registrations')
 }

packages/client/ui-workspace/tests/apply.spec.ts

@@ -14,17 +14,16 @@ async function bench() {
     path: 'name' in input ? `/projects/${input.name}` : input.path,
     title: 'new', sessionIds: [], createdAt: '0', updatedAt: '0',
   }))
-  const pickDirectory = vi.fn(async () => '/tmp/picked')
   const startSession = vi.fn()
   const rename = vi.fn(async () => ({}))
   const insertSessionBefore = vi.fn(async () => ({}))
   const open = vi.fn()
   const clear = vi.fn()
   ctx.provide('workspaces', {
-    create, pickDirectory, startSession, rename, insertSessionBefore,
+    create, startSession, rename, insertSessionBefore,
   } as never)
   ctx.provide('sessions', { open, clear } as never)
-  return { ctx, slots: ctx.get('slots') as SlotsService, create, pickDirectory, startSession, rename, insertSessionBefore, open, clear }
+  return { ctx, slots: ctx.get('slots') as SlotsService, create, startSession, rename, insertSessionBefore, open, clear }
 }
 
 type HoleName = 'sidebar.workspaces' | 'conversation.hero.workspace' | 'conversation.empty.workspace'
@@ -73,14 +72,35 @@ describe('ui-workspace apply', () => {
     expect(b.insertSessionBefore).toHaveBeenCalledWith('ws', 's1', 's2')
     await browser.createWorkspace({ name: 'project' })
     expect(b.create).toHaveBeenCalledWith({ name: 'project' })
-    await browser.pickDirectory()
-    expect(b.pickDirectory).toHaveBeenCalledOnce()
 
     const picker = (b.slots.entries('conversation.hero.workspace')[0]!.inject as () => WorkspacePickerInjected)()
     await picker.createWorkspace({ path: '/tmp/project' })
     expect(b.create).toHaveBeenCalledWith({ path: '/tmp/project' })
-    await picker.pickDirectory()
-    expect(b.pickDirectory).toHaveBeenCalledTimes(2)
+  })
+
+  it('declares the two directory-flow holes and reports their occupancy per surface', async () => {
+    const b = await bench()
+    declare(b.slots, 'sidebar.workspaces', 'conversation.hero.workspace')
+    await b.ctx.plugin({ inject: [...inject], apply }).await()
+    // Registration declared the child holes (declaration = render authorization).
+    expect(b.slots.spec('sidebar.workspaces.directoryFlow')).toMatchObject({ kind: 'single' })
+    expect(b.slots.spec('conversation.hero.workspace.directoryFlow')).toMatchObject({ kind: 'single' })
+
+    const browser = (b.slots.entries('sidebar.workspaces')[0]!.inject as () => WorkspaceBrowserInjected)()
+    const picker = (b.slots.entries('conversation.hero.workspace')[0]!.inject as () => WorkspacePickerInjected)()
+    expect(browser.hooks.directoryFlow.getSnapshot()).toBe(false)
+    expect(picker.hooks.directoryFlow.getSnapshot()).toBe(false)
+    // A flow occupant flips exactly its own surface, and the source notifies.
+    const notified = vi.fn()
+    const unsubscribe = browser.hooks.directoryFlow.subscribe(notified)
+    const dispose = b.slots.register({ name: 'sidebar.workspaces.directoryFlow' } as never, () => null)
+    expect(browser.hooks.directoryFlow.getSnapshot()).toBe(true)
+    expect(picker.hooks.directoryFlow.getSnapshot()).toBe(false)
+    await Promise.resolve()
+    expect(notified).toHaveBeenCalled()
+    dispose()
+    expect(browser.hooks.directoryFlow.getSnapshot()).toBe(false)
+    unsubscribe()
   })
 
   it('unregisters every entry on teardown', async () => {

packages/client/ui-workspace/tests/workspace-browser.spec.tsx

@@ -59,7 +59,8 @@ function mount(overrides: Partial<WorkspaceBrowserProps> = {}) {
     deleteWorkspace: vi.fn(async () => {}),
     insertSessionBefore: vi.fn(async () => {}),
     createWorkspace: vi.fn(async () => workspace('created', [])),
-    pickDirectory: vi.fn(async () => null),
+    useDirectoryFlow: bindSnapshotSelector({ getSnapshot: () => true, subscribe: () => () => {} }),
+    renderSlot: ((_name: string, owner: { open: boolean }) => (owner.open ? <div data-testid="directory-flow" /> : null)) as never,
     ...overrides,
   }
   const view = render(<WorkspaceBrowser {...props} />)

packages/client/ui-workspace/tests/workspace-picker.spec.tsx

@@ -5,6 +5,8 @@ import type {
   SessionListState, WorkspaceId, WorkspaceListState, WorkspaceView,
 } from '@deepseek-ai/dsh-client-runtime/client'
 import { WorkspaceCreateError } from '@deepseek-ai/dsh-client-runtime/client'
+import type { DirectoryFlowOwnerProps } from '../src/client/contract/slots.ts'
+import { bindSnapshotSelector } from '@deepseek-ai/dsh-client-web-react'
 import { WorkspacePicker } from '../src/client/WorkspacePicker.tsx'
 
 afterEach(cleanup)
@@ -35,14 +37,49 @@ function anchor(): { current: HTMLElement } {
   return { current: element }
 }
 
+/**
+ * Probe occupant of the directory-flow hole: records the latest owner
+ * conversation so tests drive onPicked/onCancel/onError like a composed flow
+ * package would, and renders a marker element while the flow is open.
+ */
+function flowProbe() {
+  const probe: { owner: DirectoryFlowOwnerProps | undefined } = { owner: undefined }
+  const renderSlot = ((_name: string, owner: DirectoryFlowOwnerProps) => {
+    probe.owner = owner
+    return owner.open ? <div data-testid="directory-flow" data-busy={owner.busy} /> : null
+  }) as never
+  return { probe, renderSlot }
+}
+
+/** Manual occupancy source bound like the renderer would: flip() drives the hook like a real registration change. */
+function occupancySource(initial = true) {
+  let occupied = initial
+  const listeners = new Set<() => void>()
+  const useDirectoryFlow = bindSnapshotSelector({
+    getSnapshot: () => occupied,
+    subscribe: (listener: () => void) => {
+      listeners.add(listener)
+      return () => { listeners.delete(listener) }
+    },
+  })
+  return {
+    useDirectoryFlow,
+    flip: (next: boolean) => {
+      occupied = next
+      for (const listener of [...listeners]) listener()
+    },
+  }
+}
+
 function mount(
   items: readonly WorkspaceView[] = [workspace('alpha', 'Alpha')],
   createWorkspace = vi.fn(),
-  pickDirectory = vi.fn(async () => null as string | null),
+  occupancy = occupancySource(),
 ) {
   const onPick = vi.fn()
   const onClose = vi.fn()
   const anchorRef = anchor()
+  const { probe, renderSlot } = flowProbe()
   const renderPicker = (nextItems: readonly WorkspaceView[]) => (
     <WorkspacePicker
       open
@@ -52,14 +89,15 @@ function mount(
       onPick={onPick}
       onClose={onClose}
       createWorkspace={createWorkspace}
-      pickDirectory={pickDirectory}
+      useDirectoryFlow={occupancy.useDirectoryFlow}
+      renderSlot={renderSlot}
     />
   )
   const view = render(
     renderPicker(items),
   )
   return {
-    view, onPick, onClose, createWorkspace, pickDirectory,
+    view, onPick, onClose, createWorkspace, probe, occupancy,
     rerenderItems: (nextItems: readonly WorkspaceView[]) => { view.rerender(renderPicker(nextItems)) },
   }
 }
@@ -87,65 +125,75 @@ describe('WorkspacePicker', () => {
     await waitFor(() => { expect(b.onPick).toHaveBeenCalledWith(created.workspaceId) })
   })
 
-  it('opens a native directory picker, adopts its path, and selects the returned Workspace', async () => {
+  it('opens the composed directory flow, adopts its picked path, and selects the returned Workspace', async () => {
     const created = { ...workspace('adopted'), path: '/tmp/project', title: 'project' }
     const createWorkspace = vi.fn(async () => created)
-    const pickDirectory = vi.fn(async () => '/tmp/project')
-    const b = mount([], createWorkspace, pickDirectory)
+    const b = mount([], createWorkspace)
+    expect(screen.queryByTestId('directory-flow')).toBeNull()
     chooseItem('Open local folder…')
-    expect(pickDirectory).toHaveBeenCalledOnce()
-    await waitFor(() => { expect(createWorkspace).toHaveBeenCalledWith({ path: '/tmp/project' }) })
+    expect(b.onClose).toHaveBeenCalled()
+    expect(screen.getByTestId('directory-flow')).toBeTruthy()
+    await act(async () => { b.probe.owner!.onPicked('/tmp/project') })
     expect(createWorkspace).toHaveBeenCalledWith({ path: '/tmp/project' })
     await waitFor(() => { expect(b.onPick).toHaveBeenCalledWith(created.workspaceId) })
+    // Successful adoption withdraws the flow request.
+    expect(screen.queryByTestId('directory-flow')).toBeNull()
   })
 
-  it('treats native picker cancellation as a silent no-op', async () => {
-    const b = mount([], vi.fn(), vi.fn(async () => null))
+  it('treats flow cancellation as a silent no-op', () => {
+    const b = mount([])
     chooseItem('Open local folder…')
-    await waitFor(() => { expect(b.pickDirectory).toHaveBeenCalledOnce() })
+    act(() => { b.probe.owner!.onCancel() })
+    expect(screen.queryByTestId('directory-flow')).toBeNull()
     expect(b.createWorkspace).not.toHaveBeenCalled()
     expect(b.onPick).not.toHaveBeenCalled()
     expect(screen.queryByRole('dialog')).toBeNull()
   })
 
-  it('shows a name conflict and retries through the native picker', async () => {
-    const pickDirectory = vi.fn()
-      .mockResolvedValueOnce('/one/project')
-      .mockResolvedValueOnce(null)
+  it('shows a name conflict and retries by reopening the flow', async () => {
     const createWorkspace = vi.fn(async () => {
       throw new WorkspaceCreateError({
         code: 'workspace-name-conflict', message: 'project already exists', details: { name: 'project' },
       })
     })
-    const b = mount([], createWorkspace, pickDirectory)
+    const b = mount([], createWorkspace)
     chooseItem('Open local folder…')
+    await act(async () => { b.probe.owner!.onPicked('/one/project') })
     await waitFor(() => {
       expect(screen.getByRole('dialog', { name: 'A workspace with this name already exists' })).toBeTruthy()
     })
     expect(screen.getByRole('alert').textContent).toBe('Choose a folder with a different name.')
+    // The failed adoption withdrew the flow; Choose again reopens it.
+    expect(b.probe.owner!.open).toBe(false)
     fireEvent.click(screen.getByRole('button', { name: 'Choose again' }))
-    await waitFor(() => { expect(pickDirectory).toHaveBeenCalledTimes(2) })
+    expect(b.probe.owner!.open).toBe(true)
     expect(b.onPick).not.toHaveBeenCalled()
   })
 
-  it('disables the folder action while the native picker is already open', async () => {
-    let resolve!: (path: string | null) => void
-    const pending = new Promise<string | null>((settle) => { resolve = settle })
-    const b = mount([], vi.fn(), vi.fn(() => pending))
+  it('disables every menu action from flow open through adoption, and reports busy to the flow', async () => {
+    let resolve!: (workspace: WorkspaceView) => void
+    const pending = new Promise<WorkspaceView>((settle) => { resolve = settle })
+    const created = workspace('adopted')
+    const b = mount([workspace('alpha', 'Alpha')], vi.fn(() => pending))
     chooseItem('Open local folder…')
+    // The flow is open but nothing is picked yet: a chooser pending on the
+    // host display must already block concurrent workspace actions.
+    expect(screen.getByRole<HTMLButtonElement>('menuitem', { name: 'Alpha' }).disabled).toBe(true)
+    expect(screen.getByRole<HTMLButtonElement>('menuitem', { name: 'Create a new workspace' }).disabled).toBe(true)
+    act(() => { b.probe.owner!.onPicked('/tmp/project') })
+    expect(b.probe.owner!.busy).toBe(true)
     expect(screen.getByRole<HTMLButtonElement>('menuitem', { name: 'Open local folder…' }).disabled).toBe(true)
     expect(screen.getByRole<HTMLButtonElement>('menuitem', { name: 'Create a new workspace' }).disabled).toBe(true)
-    fireEvent.click(screen.getByRole('menuitem', { name: 'Open local folder…' }))
-    expect(b.pickDirectory).toHaveBeenCalledTimes(1)
-    await act(async () => { resolve(null); await pending })
+    await act(async () => { resolve(created); await pending })
+    expect(b.probe.owner!.busy).toBe(false)
   })
 
-  it('reports non-Error native picker failures', async () => {
-    const b = mount([], vi.fn(), vi.fn(async () => { throw 'picker unavailable' }))
+  it('shows the flow-reported failure in the folder-error surface', () => {
+    const b = mount([])
     chooseItem('Open local folder…')
-    await waitFor(() => {
-      expect(screen.getByRole('alert').textContent).toBe('picker unavailable')
-    })
+    act(() => { b.probe.owner!.onError('no chooser installed') })
+    expect(screen.getByRole('alert').textContent).toBe('no chooser installed')
+    expect(screen.queryByTestId('directory-flow')).toBeNull()
     expect(b.createWorkspace).not.toHaveBeenCalled()
   })
 
@@ -215,10 +263,12 @@ describe('WorkspacePicker', () => {
   })
 
   it('waits to show its menu until an optional anchor is available', () => {
+    const { renderSlot } = flowProbe()
     render(
       <WorkspacePicker
         open useSessions={hook(sessions)} useWorkspaces={hook(workspaceState([]))}
-        onPick={vi.fn()} onClose={vi.fn()} createWorkspace={vi.fn()} pickDirectory={vi.fn()}
+        onPick={vi.fn()} onClose={vi.fn()} createWorkspace={vi.fn()}
+        useDirectoryFlow={occupancySource().useDirectoryFlow} renderSlot={renderSlot}
       />,
     )
     expect(screen.queryByRole('menu')).toBeNull()
@@ -228,12 +278,54 @@ describe('WorkspacePicker', () => {
     const state: WorkspaceListState = {
       ...workspaceState([]), phase: 'pending', state: 'loading', baselinesReady: false,
     }
+    const { renderSlot } = flowProbe()
     render(
       <WorkspacePicker
         open anchorRef={anchor()} useSessions={hook(sessions)} useWorkspaces={hook(state)}
-        onPick={vi.fn()} onClose={vi.fn()} createWorkspace={vi.fn()} pickDirectory={vi.fn()}
+        onPick={vi.fn()} onClose={vi.fn()} createWorkspace={vi.fn()}
+        useDirectoryFlow={occupancySource().useDirectoryFlow} renderSlot={renderSlot}
       />,
     )
     expect(screen.getByRole('status').textContent).toBe('Loading workspaces…')
   })
+
+  it('hides the folder entry while the directory-flow hole is empty', () => {
+    mount([], vi.fn(), occupancySource(false))
+    expect(screen.getByRole('menuitem', { name: 'Create a new workspace' })).toBeTruthy()
+    expect(screen.queryByRole('menuitem', { name: 'Open local folder…' })).toBeNull()
+  })
+
+  it('shows the folder entry when a flow package activates after the first paint', () => {
+    const b = mount([], vi.fn(), occupancySource(false))
+    expect(screen.queryByRole('menuitem', { name: 'Open local folder…' })).toBeNull()
+    // Registration changes flow through the subscription, no re-render needed.
+    act(() => { b.occupancy.flip(true) })
+    expect(screen.getByRole('menuitem', { name: 'Open local folder…' })).toBeTruthy()
+  })
+
+  it('keeps Choose again inert while the flow occupant is gone, and snaps back a flow opened over an empty hole', async () => {
+    const b = mount([], vi.fn(async () => { throw new Error('adoption failed') }))
+    chooseItem('Open local folder…')
+    await act(async () => { b.probe.owner!.onPicked('/one/project') })
+    await waitFor(() => { expect(screen.getByRole('dialog', { name: 'Couldn’t open folder' })).toBeTruthy() })
+    // The occupant unloads while the error dialog is up: retrying would open
+    // a flow nobody can serve or cancel, so the button goes inert.
+    act(() => { b.occupancy.flip(false) })
+    expect(screen.getByRole<HTMLButtonElement>('button', { name: 'Choose again' }).disabled).toBe(true)
+    // Cancel stays the way out, and the menu actions are usable again.
+    fireEvent.click(screen.getByRole('button', { name: 'Cancel' }))
+    expect(screen.getByRole<HTMLButtonElement>('menuitem', { name: 'Create a new workspace' }).disabled).toBe(false)
+  })
+
+  it('withdraws an open flow when its occupant unloads, re-enabling the menu actions', () => {
+    const b = mount([])
+    chooseItem('Open local folder…')
+    expect(screen.getByTestId('directory-flow')).toBeTruthy()
+    // The flow plugin unloads mid-interaction (HMR): nobody is left to
+    // cancel, so the owner withdraws and the actions come back.
+    act(() => { b.occupancy.flip(false) })
+    expect(b.probe.owner!.open).toBe(false)
+    expect(screen.getByRole<HTMLButtonElement>('menuitem', { name: 'Create a new workspace' }).disabled).toBe(false)
+    expect(screen.queryByRole('menuitem', { name: 'Open local folder…' })).toBeNull()
+  })
 })

packages/client/ui-workspace/tsconfig.json

@@ -8,6 +8,9 @@
     "src"
   ],
   "references": [
+    {
+      "path": "../locale"
+    },
     {
       "path": "../../../vendor/cordis"
     },