fix(host): review round 20 — canonical shape declared at the interface; hermetic home-shape spec; single resolve

packages/host/directory-picker-browse/tests/home-shape.spec.ts

@@ -2,19 +2,33 @@
  * The wire contract's home shape: a decorated HOME (trailing/repeated
  * separators, dot segments — homedir() ships it verbatim) still leaves the
  * listing carrying the resolved form, matching `path` and `crumbs[].path`.
+ * The mock points homedir at a scratch tree so the probe never scans the
+ * running machine's real home (same hermetic reasoning as service.spec's
+ * temporary tree); the mock spreads the actual module, so tmpdir stays real.
  */
 
-import { resolve } from 'node:path'
-import { expect, it, vi } from 'vitest'
+import { mkdtemp, rm } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { join, resolve } from 'node:path'
+import { afterAll, beforeAll, expect, it, vi } from 'vitest'
 import { Context } from 'cordis'
 
+let scratch: string
+
 vi.mock('node:os', async (importOriginal) => {
   const actual = await importOriginal<typeof import('node:os')>()
-  return { ...actual, homedir: () => `${actual.homedir()}/.//.` }
+  return { ...actual, homedir: () => `${scratch}/.//.` }
+})
+
+beforeAll(async () => {
+  scratch = await mkdtemp(join(tmpdir(), 'dsh-home-shape-'))
+})
+
+afterAll(async () => {
+  await rm(scratch, { recursive: true, force: true })
 })
 
 it('resolves a decorated homedir before stamping listing.home', async () => {
-  const { homedir } = await vi.importActual<typeof import('node:os')>('node:os')
   const { default: BrowseDirectoryPicker } = await import('../src/index.ts')
   const ctx = new Context()
   const fiber = ctx.plugin(BrowseDirectoryPicker)
@@ -22,7 +36,7 @@ it('resolves a decorated homedir before stamping listing.home', async () => {
   const picked = ctx.get('directoryPicker')!.capability()
   if (picked.kind !== 'browse') throw new Error('browse backend must advertise the browse capability')
   const listing = await picked.list()
-  expect(listing.home).toBe(resolve(homedir()))
+  expect(listing.home).toBe(resolve(scratch))
   expect(listing.path).toBe(listing.home)
   await fiber.dispose()
 })