diff --git a/knip.json b/knip.json
index e5e331194b..b08fe22a25 100644
--- a/knip.json
+++ b/knip.json
@@ -76,11 +76,6 @@
         "tests/**/*.ts"
       ]
     },
-    "packages/api/workspace-controller": {
-      "ignoreDependencies": [
-        "zod"
-      ]
-    },
     "packages/client/ui-approval": {
       "entry": [
         "tests/**/*.spec.tsx"
diff --git a/packages/api/workspace-controller/package.json b/packages/api/workspace-controller/package.json
index 29245fef86..bc045f38c7 100644
--- a/packages/api/workspace-controller/package.json
+++ b/packages/api/workspace-controller/package.json
@@ -76,6 +76,7 @@
     "@deepseek-ai/cordis": "workspace:^",
     "@deepseek-ai/dsh-api-gateway": "workspace:^",
     "@deepseek-ai/dsh-client-connection": "workspace:^",
+    "@deepseek-ai/dsh-host-directory-picker": "workspace:^",
     "@deepseek-ai/dsh-invariants": "workspace:^",
     "@deepseek-ai/dsh-session": "workspace:^",
     "@deepseek-ai/dsh-storage-domain": "workspace:^",
@@ -87,6 +88,7 @@
     "@deepseek-ai/dsh-api-gateway": "workspace:^",
     "@deepseek-ai/dsh-client-connection": "workspace:^",
     "@deepseek-ai/dsh-client-store": "workspace:^",
+    "@deepseek-ai/dsh-host-directory-picker": "workspace:^",
     "@deepseek-ai/dsh-invariants": "workspace:^",
     "@deepseek-ai/dsh-session": "workspace:^",
     "@deepseek-ai/dsh-storage-domain": "workspace:^",
diff --git a/packages/api/workspace-controller/src/directory-picker.ts b/packages/api/workspace-controller/src/directory-picker.ts
new file mode 100644
index 0000000000..ee58ef7b83
--- /dev/null
+++ b/packages/api/workspace-controller/src/directory-picker.ts
@@ -0,0 +1,171 @@
+/**
+ * Host directory-picking Remote owner: capability gating, cancellation, and the
+ * stable wire failure vocabulary over the `ctx.directoryPicker` seam.
+ */
+
+import { Context } from '@deepseek-ai/cordis'
+import { z } from 'zod'
+import { DirectoryPickerError } from '@deepseek-ai/dsh-host-directory-picker'
+import type { DirectoryPickerCapabilities } from '@deepseek-ai/dsh-host-directory-picker'
+// The seam owns the listing declaration; the generator requires the reference
+// site to name that package rather than this package's re-export of it.
+import type { DirectoryListing } from '@deepseek-ai/dsh-host-directory-picker/types'
+import { Remote, TypertRemoteFailure, TypertRemoteService } from '@deepseek-ai/dsh-typert-protocol'
+import type { DirectoryPickerErrorDetailsMap } from './types.ts'
+
+const createDirectoryRequestSchema = z.object({
+  path: z.string(),
+  name: z.string(),
+}).refine(
+  request => request.name.trim() !== '' && request.name !== '.' && request.name !== '..'
+    && !/[/\\]/.test(request.name),
+  { message: 'host.createDirectory requires a single non-blank path segment name' },
+)
+
+declare module '@deepseek-ai/cordis' {
+  interface Context {
+    /** Host directory-picking Remote namespace owner. */
+    directoryPickerController: DirectoryPickerController
+  }
+}
+
+/**
+ * Host service backing the generated `ctx.remote.directoryPicker` namespace. The
+ * seam it exports is abstract and therefore never a Loader entry of its own, so
+ * this controller carries the wire verbs: one composed backend serves either the
+ * native chooser or the browse primitives, and a verb the composition cannot
+ * serve is refused rather than approximated.
+ */
+export class DirectoryPickerController extends TypertRemoteService {
+  static inject = ['directoryPicker']
+
+  /** @param ctx - Host context carrying the composed directory-picking backend. */
+  constructor(ctx: Context) {
+    super(ctx, 'directoryPickerController', { namespace: 'directoryPicker' })
+  }
+
+  /**
+   * Open the host's OS chooser for a Remote caller.
+   * @param signal - caller lifetime; abort terminates the chooser.
+   * @returns the chosen absolute path, or null when the operator cancels.
+   */
+  @Remote('pick')
+  async pick(signal: AbortSignal): Promise<string | null> {
+    const capability = this.requireCapability('native', 'pick')
+    try {
+      return await capability.pick(signal)
+    } catch (error: unknown) {
+      throw cancellableFailure(error, signal, 'directory picker was aborted', 'directory picker failed')
+    }
+  }
+
+  /**
+   * List one directory level for a Remote caller's in-app browser.
+   * @param path - absolute directory to list; absent lists the home directory.
+   * @param signal - caller lifetime; abort stops the backend's scan instead of
+   *   letting it outlive a disconnected caller.
+   * @returns the level's listing with its ancestry.
+   */
+  @Remote('list')
+  async list(path: string | undefined, signal: AbortSignal): Promise<DirectoryListing> {
+    const capability = this.requireCapability('browse', 'list')
+    try {
+      return await capability.list(path, signal)
+    } catch (error: unknown) {
+      throw cancellableFailure(error, signal, 'directory listing was aborted')
+    }
+  }
+
+  /**
+   * Create one child directory for a Remote caller's in-app browser.
+   * @param path - absolute existing parent directory.
+   * @param name - single non-blank path segment.
+   * @returns the created directory's absolute path.
+   */
+  @Remote('createDirectory')
+  async createDirectory(path: string, name: string): Promise<string> {
+    const request = createDirectoryRequestSchema.safeParse({ path, name })
+    if (!request.success) {
+      throw pickerFailureOf(
+        'bad-request',
+        'invalid payload for host.createDirectory',
+        { issues: request.error.issues },
+      )
+    }
+    const capability = this.requireCapability('browse', 'createDirectory')
+    try {
+      return await capability.createDirectory(request.data.path, request.data.name)
+    } catch (error: unknown) {
+      throw browseFailure(error)
+    }
+  }
+
+  /** Resolve the capability one wire verb needs, or refuse with the kind this backend serves. */
+  private requireCapability<Kind extends keyof DirectoryPickerCapabilities>(
+    kind: Kind,
+    method: string,
+  ): DirectoryPickerCapabilities[Kind] {
+    const capability = this.ctx.directoryPicker.capability()
+    if (capability.kind !== kind) {
+      throw pickerFailureOf(
+        'directory-picker-unavailable',
+        `directoryPicker.${method} needs the ${kind} capability; the composed picker serves "${capability.kind}"`,
+        { capability: capability.kind },
+      )
+    }
+    return capability as DirectoryPickerCapabilities[Kind]
+  }
+}
+
+/**
+ * Raise one entry of the picking wire failure vocabulary.
+ * @param code - the failure code a caller discriminates on.
+ * @param message - operator-facing description.
+ * @param details - the payload this code carries.
+ * @returns the failure to throw across the Remote boundary.
+ */
+function pickerFailureOf<Code extends keyof DirectoryPickerErrorDetailsMap>(
+  code: Code,
+  message: string,
+  details: DirectoryPickerErrorDetailsMap[Code],
+): TypertRemoteFailure {
+  return new TypertRemoteFailure({ code, message, details })
+}
+
+/**
+ * Classify a browse-primitive rejection: the seam's own closed codes carry the
+ * path they are about, and anything else stays an infrastructure failure.
+ * @param error - the primitive's rejection.
+ * @returns the failure to throw across the Remote boundary.
+ */
+function browseFailure(error: unknown): TypertRemoteFailure {
+  if (error instanceof DirectoryPickerError) {
+    return pickerFailureOf(error.code, error.message, { path: error.path })
+  }
+  return pickerFailureOf('internal', errorMessage(error), {})
+}
+
+/**
+ * Classify a cancellable primitive's rejection. An abort is the caller's own
+ * timeout or disconnect, not a backend failure, so it answers `cancelled`
+ * before the business classification runs.
+ * @param error - the primitive's rejection.
+ * @param signal - the caller lifetime the primitive ran under.
+ * @param cancelled - operator-facing text for the abort outcome.
+ * @param failed - prefix for a non-seam failure, when the verb has no closed codes.
+ * @returns the failure to throw across the Remote boundary.
+ */
+function cancellableFailure(
+  error: unknown,
+  signal: AbortSignal,
+  cancelled: string,
+  failed?: string,
+): TypertRemoteFailure {
+  if (signal.aborted) return pickerFailureOf('cancelled', cancelled, {})
+  if (failed === undefined) return browseFailure(error)
+  return pickerFailureOf('internal', `${failed}: ${errorMessage(error)}`, {})
+}
+
+function errorMessage(error: unknown): string {
+  return error instanceof Error ? error.message : String(error)
+}
diff --git a/packages/api/workspace-controller/src/index.ts b/packages/api/workspace-controller/src/index.ts
index 0fbd514cd5..40ab0647f2 100644
--- a/packages/api/workspace-controller/src/index.ts
+++ b/packages/api/workspace-controller/src/index.ts
@@ -3,6 +3,7 @@
 import { Context } from '@deepseek-ai/cordis'
 import { Remote, TypertRemoteService } from '@deepseek-ai/dsh-typert-protocol'
 import { WorkspaceCommands } from './commands.ts'
+import { DirectoryPickerController } from './directory-picker.ts'
 import { WorkspaceFeed } from './feed.ts'
 import type {
   WorkspaceArchiveSessionRequest,
@@ -20,6 +21,7 @@ import type {
 } from './types.ts'
 
 export type * from './types.ts'
+export { DirectoryPickerController } from './directory-picker.ts'
 
 declare module '@deepseek-ai/cordis' {
   interface Context {
@@ -40,6 +42,11 @@ export class WorkspaceController extends TypertRemoteService {
     super(ctx, 'workspaceController', { namespace: 'workspace' })
     this.commands = new WorkspaceCommands(ctx)
     this.feed = new WorkspaceFeed(ctx)
+    // This package is the Loader entry for both Remote owners it hosts: the
+    // directory-picking seam is abstract and never an entry itself. The child
+    // stays pending until a picking backend is composed, so a host without one
+    // registers no picking namespace instead of answering an unservable verb.
+    ctx.plugin(DirectoryPickerController)
   }
 
   /**
diff --git a/packages/api/workspace-controller/src/types.ts b/packages/api/workspace-controller/src/types.ts
index f530e2ef12..552a9e20c3 100644
--- a/packages/api/workspace-controller/src/types.ts
+++ b/packages/api/workspace-controller/src/types.ts
@@ -1,9 +1,18 @@
-/** Browser-safe request, result, and state-stream vocabulary for Workspace Remote. */
+/**
+ * Browser-safe request, result, and state-stream vocabulary for the Workspace
+ * and directory-picking Remote namespaces this package owns. The picking seam
+ * declares its own listing types, so they are re-exported here rather than
+ * restated: a browser consumer reads the very declaration the backend answers.
+ */
 
 import type { SessionId } from '@deepseek-ai/dsh-session/types'
 import type { WorkspaceId } from '@deepseek-ai/dsh-workspace/types'
+import type { z as zCore } from 'zod'
+
+type ZodIssue = zCore.core.$ZodIssue
 
 export type { WorkspaceId } from '@deepseek-ai/dsh-workspace/types'
+export type { DirectoryEntry, DirectoryListing } from '@deepseek-ai/dsh-host-directory-picker/types'
 
 /** One durable Workspace projected for browser consumers. */
 export interface WorkspaceView {
@@ -43,6 +52,24 @@ export type WorkspaceError = {
   }
 }[keyof WorkspaceErrorDetailsMap]
 
+/** Stable directory-picking failure details returned by the picking wire verbs. */
+export interface DirectoryPickerErrorDetailsMap {
+  /** The directory creation request violates its semantic input constraints. */
+  'bad-request': { readonly issues: ZodIssue[] }
+  /** The verb needs an interaction the composed backend does not serve. */
+  'directory-picker-unavailable': { readonly capability: string }
+  /** The target is not fully qualified, or the backend cannot list it. */
+  'directory-unreadable': { readonly path: string }
+  /** A child of that name is already there. */
+  'directory-exists': { readonly path: string }
+  /** The parent is not fully qualified, the name is not one segment, or creation failed. */
+  'directory-create-failed': { readonly path: string }
+  /** The caller's own timeout or disconnect ended the chooser or the scan. */
+  cancelled: Record<never, never>
+  /** A backend failure with no seam code of its own. */
+  internal: Record<never, never>
+}
+
 /** Existing directory requested for Workspace adoption. */
 export interface WorkspaceCreateRequest {
   readonly path: string
diff --git a/packages/api/workspace-controller/tests/directory-picker.host.spec.ts b/packages/api/workspace-controller/tests/directory-picker.host.spec.ts
new file mode 100644
index 0000000000..32fd2dd6a1
--- /dev/null
+++ b/packages/api/workspace-controller/tests/directory-picker.host.spec.ts
@@ -0,0 +1,166 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { Context } from '@deepseek-ai/cordis'
+import { DirectoryPicker, DirectoryPickerError } from '@deepseek-ai/dsh-host-directory-picker'
+import type { DirectoryPickerCapability } from '@deepseek-ai/dsh-host-directory-picker'
+import { TypertRemoteFailure } from '@deepseek-ai/dsh-typert-protocol'
+import { DirectoryPickerController } from '../src/directory-picker.ts'
+
+const roots: Context[] = []
+
+afterEach(async () => {
+  await Promise.all(roots.splice(0).map(ctx => ctx.fiber.dispose()))
+})
+
+/** A backend serving exactly the capability one case is about. */
+class StubPicker extends DirectoryPicker {
+  static capabilityStub: DirectoryPickerCapability = { kind: 'native', pick: async () => null }
+
+  capability(): DirectoryPickerCapability {
+    return StubPicker.capabilityStub
+  }
+}
+
+const NATIVE_STUB: DirectoryPickerCapability = { kind: 'native', pick: async () => null }
+
+const BROWSE_STUB: DirectoryPickerCapability = {
+  kind: 'browse',
+  list: async (path) => {
+    if (path === '/denied') {
+      throw new DirectoryPickerError('directory-unreadable', '/denied', 'cannot list /denied')
+    }
+    const target = path ?? '/home/user'
+    return {
+      path: target,
+      home: '/home/user',
+      crumbs: [{ name: '/', path: '/', hidden: false }],
+      entries: [{ name: 'projects', path: `${target}/projects`, hidden: false }],
+      truncated: false,
+    }
+  },
+  createDirectory: async (path, name) => {
+    if (name === 'taken') {
+      throw new DirectoryPickerError('directory-exists', `${path}/${name}`, 'already exists')
+    }
+    if (name === 'unwritable') throw new Error('disk detached')
+    if (name === 'gone') throw 'the volume vanished'
+    return `${path}/${name}`
+  },
+}
+
+async function harness(capability: DirectoryPickerCapability = NATIVE_STUB) {
+  StubPicker.capabilityStub = capability
+  const ctx = new Context()
+  roots.push(ctx)
+  await ctx.plugin(StubPicker).await()
+  return new DirectoryPickerController(ctx)
+}
+
+/** The failure payload a refused wire verb carries. */
+async function refused(call: Promise<unknown>): Promise<{ code: string; message: string; details: object }> {
+  try {
+    await call
+  } catch (error: unknown) {
+    if (!(error instanceof TypertRemoteFailure)) throw error
+    return { ...error.failure }
+  }
+  throw new Error('the call was expected to be refused')
+}
+
+describe('directoryPicker pick Remote', () => {
+  it('answers the selected path or the operator\'s cancellation', async () => {
+    const selected = await harness({ kind: 'native', pick: async () => '/tmp/project' })
+    expect(await selected.pick(new AbortController().signal)).toBe('/tmp/project')
+
+    const cancelled = await harness(NATIVE_STUB)
+    expect(await cancelled.pick(new AbortController().signal)).toBeNull()
+  })
+
+  it('reports an aborted chooser as cancelled and any other failure as internal', async () => {
+    const picker = await harness({
+      kind: 'native',
+      pick: signal => new Promise((_resolve, reject) => {
+        signal.addEventListener('abort', () => { reject(new Error('aborted')) }, { once: true })
+      }),
+    })
+    const abort = new AbortController()
+    const pending = refused(picker.pick(abort.signal))
+    abort.abort()
+    expect((await pending).code).toBe('cancelled')
+
+    const broken = await harness({ kind: 'native', pick: async () => { throw new Error('no chooser installed') } })
+    const failure = await refused(broken.pick(new AbortController().signal))
+    expect(failure.code).toBe('internal')
+    expect(failure.message).toContain('no chooser installed')
+  })
+
+  it('refuses the native verb under a browse composition', async () => {
+    const picker = await harness(BROWSE_STUB)
+    const failure = await refused(picker.pick(new AbortController().signal))
+    expect(failure.code).toBe('directory-picker-unavailable')
+    expect(failure.message).toContain('needs the native capability')
+    expect(failure.details).toEqual({ capability: 'browse' })
+  })
+})
+
+describe('directoryPicker browse Remotes', () => {
+  it('serves listings and creation, defaulting to the home directory', async () => {
+    const picker = await harness(BROWSE_STUB)
+    const signal = new AbortController().signal
+    expect(await picker.list(undefined, signal)).toMatchObject({ path: '/home/user', home: '/home/user' })
+    expect(await picker.list('/home/user/projects', signal))
+      .toMatchObject({ path: '/home/user/projects' })
+    expect(await picker.createDirectory('/home/user', 'fresh')).toBe('/home/user/fresh')
+  })
+
+  it('maps the seam\'s typed failures and folds unknown throws to internal', async () => {
+    const picker = await harness(BROWSE_STUB)
+    expect(await refused(picker.list('/denied', new AbortController().signal)))
+      .toMatchObject({ code: 'directory-unreadable', details: { path: '/denied' } })
+    expect((await refused(picker.createDirectory('/home/user', 'taken'))).code).toBe('directory-exists')
+    expect((await refused(picker.createDirectory('/home/user', 'unwritable'))).code).toBe('internal')
+
+    const thrown = await refused(picker.createDirectory('/home/user', 'gone'))
+    expect(thrown).toMatchObject({ code: 'internal', message: 'the volume vanished' })
+  })
+
+  it('rejects invalid child names before capability dispatch', async () => {
+    const createDirectory = vi.fn(async (path: string, name: string) => `${path}/${name}`)
+    const picker = await harness({
+      kind: 'browse',
+      list: (path, signal) => BROWSE_STUB.list(path, signal),
+      createDirectory,
+    })
+
+    for (const name of ['', ' ', '.', '..', 'a/b', 'a\\b']) {
+      const failure = await refused(picker.createDirectory('/home/user', name))
+      expect(failure).toMatchObject({
+        code: 'bad-request',
+        message: 'invalid payload for host.createDirectory',
+      })
+      expect(Array.isArray(Reflect.get(failure.details, 'issues'))).toBe(true)
+    }
+    expect(createDirectory).not.toHaveBeenCalled()
+  })
+
+  it('reports an aborted listing as cancelled', async () => {
+    const picker = await harness({
+      kind: 'browse',
+      list: (_path, signal) => new Promise((_resolve, reject) => {
+        signal?.addEventListener('abort', () => { reject(new Error('scan aborted')) }, { once: true })
+      }),
+      createDirectory: async () => '/never',
+    })
+    const abort = new AbortController()
+    const pending = refused(picker.list(undefined, abort.signal))
+    abort.abort()
+    expect((await pending).code).toBe('cancelled')
+  })
+
+  it('refuses the browse verbs under a native composition', async () => {
+    const picker = await harness()
+    expect(await refused(picker.list(undefined, new AbortController().signal)))
+      .toMatchObject({ code: 'directory-picker-unavailable', details: { capability: 'native' } })
+    expect(await refused(picker.createDirectory('/x', 'y')))
+      .toMatchObject({ code: 'directory-picker-unavailable', details: { capability: 'native' } })
+  })
+})
diff --git a/packages/api/workspace-controller/tsconfig.client.json b/packages/api/workspace-controller/tsconfig.client.json
index 46d392dff3..9979b769f6 100644
--- a/packages/api/workspace-controller/tsconfig.client.json
+++ b/packages/api/workspace-controller/tsconfig.client.json
@@ -17,6 +17,7 @@
     { "path": "../../client/connection/tsconfig.client.json" },
     { "path": "../../client/store" },
     { "path": "../../core/session" },
+    { "path": "../../host/directory-picker" },
     { "path": "../../typert/protocol" },
     { "path": "../../workspace/workspace" }
   ]
diff --git a/packages/api/workspace-controller/tsconfig.host.json b/packages/api/workspace-controller/tsconfig.host.json
index 76c584fd01..4b98892781 100644
--- a/packages/api/workspace-controller/tsconfig.host.json
+++ b/packages/api/workspace-controller/tsconfig.host.json
@@ -10,11 +10,13 @@
     "src/invariant.ts",
     "src/types.ts",
     "src/commands.ts",
+    "src/directory-picker.ts",
     "src/feed.ts"
   ],
   "references": [
     { "path": "../../../vendor/cordis" },
     { "path": "../../core/session" },
+    { "path": "../../host/directory-picker" },
     { "path": "../../runtime-diagnostics/invariants" },
     { "path": "../../storage/storage-domain" },
     { "path": "../../typert/protocol" },
diff --git a/packages/host/directory-picker-browse/src/index.ts b/packages/host/directory-picker-browse/src/index.ts
index adbe6d09ad..01fe5b9cd2 100644
--- a/packages/host/directory-picker-browse/src/index.ts
+++ b/packages/host/directory-picker-browse/src/index.ts
@@ -303,8 +303,8 @@ export default class BrowseDirectoryPicker extends DirectoryPicker {
       throw new DirectoryPickerError('directory-create-failed', path, `cannot create under "${path}": not a fully qualified parent path`)
     }
     const parent = resolve(path)
-    // The backend owns segment validation (the wire schema also refuses these,
-    // but direct service consumers must hit the same fence).
+    // The backend owns segment validation; the Remote controller also refuses
+    // invalid wire input, but direct service consumers must hit the same fence.
     if (name.trim() === '' || name === '.' || name === '..' || /[/\\]/.test(name)) {
       throw new DirectoryPickerError('directory-create-failed', join(parent, name), `"${name}" is not a single path segment`)
     }
diff --git a/packages/host/directory-picker/src/invariant.ts b/packages/host/directory-picker/src/invariant.ts
index abf29856fc..5c44aac9af 100644
--- a/packages/host/directory-picker/src/invariant.ts
+++ b/packages/host/directory-picker/src/invariant.ts
@@ -12,7 +12,7 @@ export const inject = ['invariants']
 
 /**
  * No runtime invariant: this stateless Service Definition owns the capability
- * vocabulary, while backends and the RPC consumer own observations.
+ * vocabulary, while backends and the Remote controller own observations.
  */
 const install: InvariantInstaller = () => {}
 
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index fcc43f58e1..80cb2119f1 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -838,6 +838,9 @@ importers:
       '@deepseek-ai/dsh-client-store':
         specifier: workspace:^
         version: link:../../client/store
+      '@deepseek-ai/dsh-host-directory-picker':
+        specifier: workspace:^
+        version: link:../../host/directory-picker
       '@deepseek-ai/dsh-invariants':
         specifier: workspace:^
         version: link:../../runtime-diagnostics/invariants