test(snapshot): cover session-scoped sandbox roots

packages/support/acp-snapshot/tests/harness.spec.ts

@@ -1,7 +1,7 @@
 import { mkdtemp, rm, writeFile } from 'node:fs/promises'
 import { once } from 'node:events'
 import { tmpdir } from 'node:os'
-import { delimiter, join } from 'node:path'
+import { delimiter, join, relative, sep } from 'node:path'
 import { fileURLToPath } from 'node:url'
 import { afterAll, describe, expect, it, vi } from 'vitest'
 import { PROTOCOL_VERSION } from '@agentclientprotocol/sdk'
@@ -345,6 +345,22 @@ describe('runScenario', () => {
     expect(result.rawStdout).toContain('workspace:seeded.txt')
   })
 
+  it('creates the generated workspace under an explicit parent', { timeout: 20_000 }, async () => {
+    const { fixtureFile } = await scenario({})
+    const workspaceParent = await mkdtemp(join(tmpdir(), 'acp-snap-parent-'))
+    tempDirs.push(workspaceParent)
+
+    const result = await runScenario(
+      { steps: boot },
+      { agent: AGENT, mode: 'replay', fixtureFile, workspaceParent },
+    )
+
+    const child = relative(workspaceParent, result.cwd)
+    expect(child).not.toBe('')
+    expect(child).not.toBe('..')
+    expect(child.startsWith(`..${sep}`)).toBe(false)
+  })
+
   it('promptAndCancel waits for the streamed chunk, cancels, and settles the prompt', { timeout: 20_000 }, async () => {
     const { fixtureFile } = await scenario({ prompt: 'hang-until-cancel' })
     const result = await runScenario(

packages/support/acp-snapshot/tests/suite.spec.ts

@@ -46,7 +46,14 @@ const RECORD_SRC = fileURLToPath(new URL('./fixtures/record-suite', import.meta.
 // Replay pins explicit header classes; recording covers the default fallback.
 const REPLAY_SCENARIOS: Scenario[] = [
   { name: 'pin-turn', hasModelTurn: true, recorded: true, pinsHeader: true, expectedHeaderChanges: 1, headerClass: 'main' },
-  { name: 'plain-turn', hasModelTurn: true, recorded: true, headerClass: 'main', configPath: AGENT.configPath },
+  {
+    name: 'plain-turn',
+    hasModelTurn: true,
+    recorded: true,
+    headerClass: 'main',
+    configPath: AGENT.configPath,
+    workspaceParent: tmpdir(),
+  },
   { name: 'no-model', hasModelTurn: false, recorded: false, headerClass: 'main' },
   { name: 'blocked-log', hasModelTurn: false, comparesLog: true, recorded: false, headerClass: 'main' },
   { name: 'authored-error', hasModelTurn: true, recorded: false, overridden: true, headerClass: 'main' },