Merge remote-tracking branch 'origin/doc/host-client-group-readmes' into feat/directory-picker

# Conflicts:
#	packages/client/connection/src/client/fixture.ts
#	packages/client/connection/tests/fake-api.ts
#	packages/client/runtime/src/client/workspaces/service.ts
#	packages/client/runtime/tests/fake-api.ts
#	packages/client/ui-workspace/src/client/WorkspaceBrowser.tsx
#	packages/client/ui-workspace/src/client/WorkspacePicker.tsx
#	packages/client/ui-workspace/tests/workspace-picker.spec.tsx
#	packages/host/apiproxy/README.i18n.yaml
#	packages/host/apiproxy/src/api-proxy.ts
#	packages/host/apiproxy/src/api/host.schema.ts
#	packages/host/apiproxy/src/api/host.ts
#	packages/host/apiproxy/src/api/rpc-map.ts
#	packages/host/apiproxy/src/fetch/client.ts
#	packages/host/apiproxy/src/fetch/handler.ts
#	packages/host/apiproxy/tests/api-proxy-workspace.spec.ts
#	packages/host/apiproxy/tests/client-handler.spec.ts
#	packages/host/apiproxy/tests/fetch-carrier.spec.ts

packages/client/ui-workspace/tests/browser-styles.spec.ts

@@ -0,0 +1,48 @@
+/**
+ * WorkspaceBrowser scroll-region style contract, asserted against the CSS text
+ * on disk: the session list reserves its scrollbar gutter so the scrollbar
+ * cannot overlay row trailing content, and reserves it whether or not the list
+ * currently overflows so expanding a group does not shift rows sideways.
+ */
+import { readFileSync } from 'node:fs'
+import { fileURLToPath } from 'node:url'
+import { describe, expect, it } from 'vitest'
+
+const css = readFileSync(fileURLToPath(new URL('../src/client/WorkspaceBrowser.module.css', import.meta.url)), 'utf8')
+
+/**
+ * Declarations of one class rule, keyed by property with whitespace collapsed.
+ * Declaration order and trailing semicolons are normalized away.
+ * @param className - local class name, without the leading dot.
+ * @returns the rule's declarations, or undefined when no such rule exists.
+ */
+function declarations(className: string): Map<string, string> | undefined {
+  const withoutComments = css.replace(/\/\*[\s\S]*?\*\//g, ' ')
+  const match = new RegExp(String.raw`(^|[\s,}])\.${className}\s*\{([^{}]*)\}`).exec(withoutComments)
+  if (match === null) return undefined
+  const found = new Map<string, string>()
+  // The body group is unconditional in the pattern; the fallback only satisfies
+  // noUncheckedIndexedAccess.
+  for (const part of (match[2] ?? '').split(';')) {
+    const colon = part.indexOf(':')
+    if (colon === -1) continue
+    found.set(part.slice(0, colon).trim(), part.slice(colon + 1).trim().replace(/\s+/g, ' '))
+  }
+  return found
+}
+
+describe('WorkspaceBrowser.module.css list', () => {
+  const list = declarations('list')
+
+  it('is the scrolling region', () => {
+    expect(list).toBeDefined()
+    expect(list!.get('overflow-y')).toBe('auto')
+  })
+
+  it('reserves the scrollbar gutter unconditionally', () => {
+    // Row trailing content sits flush against the row's right padding, so an
+    // overlay scrollbar covers it. `stable` keeps the reservation when the list
+    // is short enough not to scroll, so expanding a group does not shift rows.
+    expect(list!.get('scrollbar-gutter')).toBe('stable')
+  })
+})

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

@@ -264,25 +264,23 @@ describe('WorkspaceBrowser', () => {
     }
   })
 
-  it('rail create-workspace expands the shell and opens the picker; wide toggles in place', () => {
+  it('rail create-workspace toggles the create-only picker in place, without expanding', async () => {
     const expandSidebar = vi.fn()
-    const b = mount({ wide: false, expandSidebar, useWorkspaces: hook(workspaceState([workspace('alpha', [])])) })
+    mount({ wide: false, expandSidebar, useWorkspaces: hook(workspaceState([workspace('alpha', [])])) })
     fireEvent.click(screen.getByRole('button', { name: 'Create workspace' }))
-    expect(expandSidebar).toHaveBeenCalledTimes(1)
-    rerender(b, { wide: true })
-    // The picker menu is open (anchored on the ＋); picking starts a session.
-    fireEvent.click(screen.getByRole('menuitem', { name: 'alpha' }))
-    expect(b.props.startSession).toHaveBeenCalledWith(wid('alpha'))
-    expect(screen.queryByRole('menu')).toBeNull()
-    // Wide toggle: open and close without expand requests.
-    fireEvent.click(screen.getByRole('button', { name: 'Create workspace' }))
-    expect(screen.getByRole('menu')).toBeTruthy()
+    expect(expandSidebar).not.toHaveBeenCalled()
+    // Flush the advertised-kind read that gates the local-folder entry.
+    await act(async () => {})
+    // createOnly: existing workspaces are not listed, only the create actions.
+    expect(screen.queryByRole('menuitem', { name: 'alpha' })).toBeNull()
+    expect(screen.getByRole('menuitem', { name: 'Open local folder…' })).toBeTruthy()
+    // Toggle: open and close in place.
     fireEvent.click(screen.getByRole('button', { name: 'Create workspace' }))
     expect(screen.queryByRole('menu')).toBeNull()
-    expect(expandSidebar).toHaveBeenCalledTimes(1)
 
     // Escape closes the picker through its own onClose.
     fireEvent.click(screen.getByRole('button', { name: 'Create workspace' }))
+    expect(screen.getByRole('menu')).toBeTruthy()
     fireEvent.keyDown(document, { key: 'Escape' })
     expect(screen.queryByRole('menu')).toBeNull()
   })

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

@@ -209,6 +209,8 @@ describe('WorkspacePicker', () => {
   it('reports non-Error creation failures', async () => {
     const b = mount([], vi.fn(async () => { throw 'permission denied' }))
     await chooseItem('Create a new workspace')
+    // The name field starts empty (no prefill); a name is required to submit.
+    fireEvent.change(screen.getByLabelText('New workspace name'), { target: { value: 'broken' } })
     fireEvent.click(screen.getByRole('button', { name: 'Create workspace' }))
     await waitFor(() => {
       expect(screen.getByRole('alert').textContent).toBe('Workspace creation failed: permission denied')