test(agent-presets): keep one write regression after the merge

The lower layer now carries the same test, and the merge kept both copies.

packages/preset/agent-presets/tests/mount.spec.ts

@@ -288,55 +288,3 @@ describe('attributing a service to a subtree', () => {
   })
 })
 
-describe('the preset file is an input, never a persistence target', () => {
-  it('survives a row that disposes itself, which makes the Loader persist a tree', async () => {
-    // The preset lives in a temp root, not under `fixtures/`: without the
-    // `write()` override the Loader REWRITES the composition it read, so a
-    // committed fixture would be mutated by the very run that proves the bug
-    // and every later run would compare against the damaged file and pass.
-    const root = await mkdtemp(join(tmpdir(), 'dsh-preset-write-'))
-    const dir = join(root, 'self-disposing')
-    await mkdir(dir)
-    const path = join(dir, COMPOSITION_FILE)
-    const composition = [
-      '- id: tool-kept',
-      `  name: ${join(FIXTURES, 'plugins', 'contribute.js')}`,
-      '  config:',
-      '    tool: kept',
-      '- id: goes-away',
-      `  name: ${join(FIXTURES, 'plugins', 'self-dispose.js')}`,
-      '',
-    ].join('\n')
-    await writeFile(path, composition)
-
-    const scoped = new Context()
-    scoped.baseUrl = pathToFileURL(FIXTURES).href + '/'
-    await scoped.plugin(Loader)
-    scoped.loader.builtins.include = Include
-    await scoped.plugin(LlmService)
-    await scoped.plugin(SessionStore)
-    await scoped.plugin(SystemPrompt, { persona: '' })
-    await scoped.plugin(ToolRegistry)
-    await scoped.plugin(AgentRegistry)
-    await scoped.plugin(AgentLoop, { agents: [] })
-    await scoped.plugin(AgentPresets, { default: 'self-disposing', roots: [{ path: root, trust: 'user' as const }] })
-
-    await scoped.agents.create({
-      sessionId: SessionId('sess-self-dispose'),
-      setup: async (agentCtx: Context) => void await scoped.agentPresets.mount(agentCtx),
-    })
-    await (globalThis as { __SELF_DISPOSED__?: Promise<unknown> }).__SELF_DISPOSED__
-    // Slack past the deterministic signal above, not a race the number has to
-    // win. The write rides the Loader's fiber-unload listener, which stamps
-    // `disabled: true` and calls `write()` in the same synchronous step; once
-    // the self-dispose has settled, a regression has already written. Polling
-    // would not help — the assertion is an ABSENCE, and no amount of waiting
-    // proves one — so the wait only has to clear settlement.
-    await new Promise(resolve => setTimeout(resolve, 50))
-
-    // Inherited, `EntryTree.write()` persists the dying tree — stamping
-    // `disabled: true` onto the row and, in the shipped case, truncating the
-    // composition every session shares.
-    expect(await readFile(path, 'utf8')).toBe(composition)
-  })
-})