feat(host,client): compose directory picking through slots — dual-face -native, no wire advertisement

ui-workspace's two trigger surfaces each declare a single-kind directory-flow
hole (conversation.hero.workspace.directoryFlow / sidebar.workspaces.directoryFlow,
same owner contract) and keep only the trigger and the adoption: the Open-local-
folder entry renders while the surface's hole is occupied, and the occupant
reports one picked path per open through the hole's owner conversation
(open/busy/onPicked/onCancel/onError).

directory-picker-native becomes dual-face: its browser half fills both holes
with a renderless occupant driving host.pickDirectory, so the cordis.yml row
that mounts the backend also composes the client interaction — a mismatch is
impossible and a second flow package fails at client load.

With composition wiring both sides, the host.describe.directoryPicker
advertisement and the client's kind branching lose their last consumer:
the field, WorkspacesService.directoryPickerKind(), the DirectoryPickerKind
wire type, and the picker's per-open describe read are deleted. The connection
fixture now serves a deterministic pickDirectory path so the keyless snapshot
drives the full pick-then-adopt flow. ui-workspace's hand-rolled declaration
deferral is replaced by the deferRegistration helper it duplicated.

packages/host/apiproxy/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/host/apiproxy/README.md
-README.md: 3639722ab25826af8f7a0721f22d244f78b4210b
-README.zh.md: 3ac81fb412d4e4caf192953bc7a7c846a1d29965
+README.md: ca4471454f5be5d3fcba38ce665d4fb3fbd85e74
+README.zh.md: 953539e1198a52b2bf7cdd9ca1b0d263cc2ae6f9

packages/host/apiproxy/README.md

@@ -18,7 +18,7 @@ Session model routing is a session-domain contract. `session.models` returns the
 
 Workspace and Session lists are separate reconnect baselines. `workspace.create` creates a unique name or adopts an existing directory, `workspace.delete` removes only the Workspace registration, `session.create` accepts an optional preallocated Session id, and `host/workspace-changed`, `host/workspace-removed`, plus `host/session-added` carry committed increments in either arrival order. Registration deletion preserves the directory and session logs; its Sessions remain in `session.list` and become Ungrouped. `SessionSummary.blank` and the `host/session-added` frame carry the derived zero-events bit: clients hide blank sessions and reuse them per workspace, flip blank on the first `host/session-status(running:true)`, and treat `session.list` as the reconnect authority; cold summaries are never blank because lazy persistence keeps never-appended sessions out of `list()`.
 
-Directory picking delegates to the composed `ctx.directoryPicker` backend ([the directory-picker seam](../directory-picker/README.md)); `host.describe.directoryPicker` advertises the capability kind the client renders for, and a method called outside the advertised kind fails with `directory-picker-unavailable`. Under `native`, `host.pickDirectory` opens one native chooser and returns its selected path (`null` on cancel); this user-paced method is the sole unary call exempt from the default 30-second timeout, and caller/connection aborts still propagate to the native process. Under `browse`, `host.listDirectory` returns one name-sorted directory level with breadcrumb ancestry, a `home` anchor, and host-owned `hidden` flags (absent path = home directory), and `host.createDirectory` creates one validated child segment; the backend's typed failures map 1:1 onto the `directory-unreadable`/`directory-exists`/`directory-create-failed` codes. The browser carrier's prefix-wide trust fence (dsh-client-connection) covers all of these like every other `/api` request.
+Directory picking delegates to the composed `ctx.directoryPicker` backend ([the directory-picker seam](../directory-picker/README.md)); a method called outside the composed capability's kind fails with `directory-picker-unavailable` (the client needs no advertisement — the composed picker package's own client half renders the matching interaction). Under `native`, `host.pickDirectory` opens one native chooser and returns its selected path (`null` on cancel); this user-paced method is the sole unary call exempt from the default 30-second timeout, and caller/connection aborts still propagate to the native process. Under `browse`, `host.listDirectory` returns one name-sorted directory level with breadcrumb ancestry, a `home` anchor, and host-owned `hidden` flags (absent path = home directory), and `host.createDirectory` creates one validated child segment; the backend's typed failures map 1:1 onto the `directory-unreadable`/`directory-exists`/`directory-create-failed` codes. The browser carrier's prefix-wide trust fence (dsh-client-connection) covers all of these like every other `/api` request.
 
 `host.openPath` opens a filesystem path with the operating system's default application (`open` on macOS, `Invoke-Item` on Windows, `xdg-open` on Linux). The opener is injectable for tests. The browser carrier applies the same loopback, same-origin restriction as `host.pickDirectory`.
 

packages/host/apiproxy/README.zh.md

@@ -18,7 +18,7 @@
 
 Workspace 列表与 Session 列表是相互独立的重连基线。`workspace.create` 会创建唯一名称或接纳现有目录，`workspace.delete` 只移除 Workspace 注册记录，`session.create` 接受可选的预分配 Session id，`host/workspace-changed`、`host/workspace-removed` 与 `host/session-added` 则以任意到达顺序携带已提交的增量。删除注册记录会保留目录和会话日志；相关 Session 仍留在 `session.list` 中，并进入 Ungrouped。`SessionSummary.blank` 与 `host/session-added` 帧携带派生的零事件位：客户端隐藏空白会话并按 workspace 复用它们，在首个 `host/session-status(running:true)` 时翻转 blank，并以 `session.list` 作为重连权威；冷会话摘要永远不是空白：惰性持久化让从未追加过事件的会话根本不出现在 `list()` 中。
 
-目录选择委托给组合的 `ctx.directoryPicker` 后端（[目录选择 seam](../directory-picker/README.md)）；`host.describe.directoryPicker` 广播客户端应按其渲染的能力 kind，调用广播之外的方法会以 `directory-picker-unavailable` 失败。在 `native` 下，`host.pickDirectory` 打开一个原生选择器并返回选中路径（取消为 `null`）；该方法需等待用户完成操作，是唯一不受默认 30 秒超时限制的一元调用，调用方与连接的中止仍会传播至原生进程。在 `browse` 下，`host.listDirectory` 返回一个按名称排序的目录层级，携带面包屑祖先链、`home` 锚点与宿主判定的 `hidden` 标志（不带路径即家目录），`host.createDirectory` 创建一个经校验的子段；后端的类型化失败 1:1 映射为 `directory-unreadable`／`directory-exists`／`directory-create-failed` 错误码。浏览器载体的前缀级信任栅栏（dsh-client-connection）像覆盖其他所有 `/api` 请求一样覆盖上述全部方法。
+目录选择委托给组合的 `ctx.directoryPicker` 后端（[目录选择 seam](../directory-picker/README.md)）；调用组合能力 kind 之外的方法会以 `directory-picker-unavailable` 失败（客户端不需要广播——组合的选择器包自己的 client half 渲染匹配的交互）。在 `native` 下，`host.pickDirectory` 打开一个原生选择器并返回选中路径（取消为 `null`）；该方法需等待用户完成操作，是唯一不受默认 30 秒超时限制的一元调用，调用方与连接的中止仍会传播至原生进程。在 `browse` 下，`host.listDirectory` 返回一个按名称排序的目录层级，携带面包屑祖先链、`home` 锚点与宿主判定的 `hidden` 标志（不带路径即家目录），`host.createDirectory` 创建一个经校验的子段；后端的类型化失败 1:1 映射为 `directory-unreadable`／`directory-exists`／`directory-create-failed` 错误码。浏览器载体的前缀级信任栅栏（dsh-client-connection）像覆盖其他所有 `/api` 请求一样覆盖上述全部方法。
 
 `host.openPath` 会用操作系统的默认应用打开一个文件系统路径（macOS 为 `open`，Windows 为 `Invoke-Item`，Linux 为 `xdg-open`）。打开器可在测试中注入。浏览器载体对其施加与 `host.pickDirectory` 相同的回环、同源限制。
 

packages/host/apiproxy/src/api-proxy.ts

@@ -1009,7 +1009,6 @@ export function createApiProxy(ctx: Context, defaults: ApiProxyDefaults): ApiPro
           provider: defaults.provider,
           model: defaults.model,
           attachedSessions: ctx.agents.list().length,
-          directoryPicker: ctx.directoryPicker.capability().kind,
         }))
       },
 

packages/host/apiproxy/src/api/host.schema.ts

@@ -19,7 +19,6 @@ export const hostDescribeValueSchema = z.object({
   attachedSessions: z.number().int().nonnegative(),
   // Open string, not a literal union: unknown kinds must survive the wire so
   // a merge-added capability can advertise (the client hides the affordance).
-  directoryPicker: z.string(),
 }) satisfies z.ZodType<Wire<ResponseValue<'host.describe'>>>
 
 /** host.pickDirectory request payload (empty object literal). */

packages/host/apiproxy/src/api/host.ts

@@ -5,18 +5,6 @@
 
 import type { RpcRequest, RpcResponse } from './rpc.ts'
 
-/**
- * The composed directory-picker interaction the host serves (mirror of the
- * `ctx.directoryPicker` capability kind): `native` = one OS chooser on
- * the host display (`host.pickDirectory`); `browse` = in-app listing/creation
- * primitives (`host.listDirectory`/`host.createDirectory`). Calling a method
- * outside the advertised kind fails with `directory-picker-unavailable`.
- * The wire preserves kinds beyond the two with methods here (a merge-added
- * capability advertises before its RPCs exist); the client's documented
- * default for a kind it does not recognize is to hide the picking affordance.
- */
-export type DirectoryPickerKind = 'native' | 'browse' | (string & {})
-
 /** One directory row of a listing: a child entry or a breadcrumb ancestor. */
 export interface DirectoryEntry {
   /** Base name shown in a browser row (a root crumb carries its full path). */
@@ -51,7 +39,6 @@ export interface HostApi {
    * applied when a new agent doesn't specify them explicitly, absent when the host configures
    * no explicit default (the adapter falls back internally);
    * attachedSessions = count of currently attached sessions (those with a live agent);
-   * directoryPicker = the composed picker interaction the client renders for.
    */
   describe(request: RpcRequest<{}>): Promise<RpcResponse<{
     version: string
@@ -59,7 +46,6 @@ export interface HostApi {
     provider?: string
     model?: string
     attachedSessions: number
-    directoryPicker: DirectoryPickerKind
   }>>
 
   /**

packages/host/apiproxy/src/api/index.ts

@@ -29,7 +29,7 @@ export type {
   HistoryEntry, ModelCatalogFailure, ModelCatalogModel, ModelProviderGroup, ModelReasoning,
   ModelReasoningEffort, ModelTarget, SessionModels, SessionProjectionsBlock, SessionsApi, SessionSummary,
 } from './sessions.ts'
-export type { DirectoryEntry, DirectoryListing, DirectoryPickerKind, HostApi } from './host.ts'
+export type { DirectoryEntry, DirectoryListing, HostApi } from './host.ts'
 export type { WorkspaceApi, WorkspaceId, WorkspaceView } from './workspace.ts'
 export type { CommandsApi, CommandDescriptor } from './commands.ts'
 export type { SkillsApi, SkillEntry } from './skills.ts'

packages/host/apiproxy/tests/api-proxy-workspace.spec.ts

@@ -192,17 +192,14 @@ describe('host.listDirectory / host.createDirectory', () => {
     })
   })
 
-  it('refuses the browse RPCs under a native composition and advertises the kind in describe', async () => {
+  it('refuses the browse RPCs under a native composition', async () => {
     const { api } = await harness()
-    expect((await api.host.describe(request({}))).result).toMatchObject({ ok: true, value: { directoryPicker: 'native' } })
     expect((await api.host.listDirectory(request({}))).result).toMatchObject({
       ok: false, error: { code: 'directory-picker-unavailable', details: { capability: 'native' } },
     })
     expect((await api.host.createDirectory(request({ path: '/x', name: 'y' }))).result).toMatchObject({
       ok: false, error: { code: 'directory-picker-unavailable', details: { capability: 'native' } },
     })
-    const browse = await harness(undefined, BROWSE_STUB)
-    expect((await browse.api.host.describe(request({}))).result).toMatchObject({ ok: true, value: { directoryPicker: 'browse' } })
   })
 })
 

packages/host/apiproxy/tests/client-handler.spec.ts

@@ -48,7 +48,7 @@ function scriptedApi(overrides: {
       ...overrides.sessions,
     },
     host: {
-      describe: r => ok(r, { version: '0-test', cwd: '/t', attachedSessions: 0, directoryPicker: 'browse' as const }),
+      describe: r => ok(r, { version: '0-test', cwd: '/t', attachedSessions: 0 }),
       pickDirectory: r => ok(r, { path: null }),
       listDirectory: r => ok(r, { path: '/t', home: '/t', crumbs: [], entries: [] }),
       createDirectory: r => ok(r, { path: '/t/new' }),

packages/host/apiproxy/tests/fetch-carrier.spec.ts

@@ -76,7 +76,7 @@ function fakeApi(overrides: Partial<{ muxFrames: MuxFrame[]; hostFrames: HostFra
     },
     host: {
       async describe(request) {
-        return { rpcId: request.rpcId, result: { ok: true, value: { version: 'v', cwd: '/w', attachedSessions: 0, directoryPicker: 'native' as const } } }
+        return { rpcId: request.rpcId, result: { ok: true, value: { version: 'v', cwd: '/w', attachedSessions: 0 } } }
       },
       async pickDirectory(request) {
         return { rpcId: request.rpcId, result: { ok: true, value: { path: null } } }

packages/host/apiproxy/tests/rpc-schemas.spec.ts

@@ -218,12 +218,9 @@ describe('sessions domain schemas', () => {
 describe('host domain schemas', () => {
   it('validates describe request/value', () => {
     expect(hostDescribeRequestSchema.parse({})).toEqual({})
-    const value = hostDescribeValueSchema.parse({ version: '1', cwd: '/x', provider: 'p', model: 'm', attachedSessions: 2, directoryPicker: 'native' })
+    const value = hostDescribeValueSchema.parse({ version: '1', cwd: '/x', provider: 'p', model: 'm', attachedSessions: 2 })
     expect(value.attachedSessions).toBe(2)
-    expect(hostDescribeValueSchema.parse({ version: '1', cwd: '/x', attachedSessions: 0, directoryPicker: 'browse' }).provider).toBeUndefined()
-    // A kind beyond the two with methods survives the wire (merge-added
-    // capabilities advertise; the client hides the affordance).
-    expect(hostDescribeValueSchema.parse({ version: '1', cwd: '/x', attachedSessions: 0, directoryPicker: 'other' }).directoryPicker).toBe('other')
+    expect(hostDescribeValueSchema.parse({ version: '1', cwd: '/x', attachedSessions: 0 }).provider).toBeUndefined()
   })
 
   it('validates the browse listing/creation payloads', () => {