diff --git a/apps/cli/config/agent-presets/standard/agent.cordis.yml b/apps/cli/config/agent-presets/standard/agent.cordis.yml
index ec4f71a849..41d1d81a90 100644
--- a/apps/cli/config/agent-presets/standard/agent.cordis.yml
+++ b/apps/cli/config/agent-presets/standard/agent.cordis.yml
@@ -227,6 +227,8 @@
 
 - id: tool-todo
   name: '@deepseek-ai/dsh-tool-todo'
+  config:
+    allowParallelInProgress: true
 
 # The `web` service and its search provider stay in the host composition; only
 # the model-facing tool is per-session.
diff --git a/packages/preset/agent-presets/tests/fixtures/plugins/contribute.js b/packages/preset/agent-presets/tests/fixtures/plugins/contribute.js
index b7b67be5d6..0d03277605 100644
--- a/packages/preset/agent-presets/tests/fixtures/plugins/contribute.js
+++ b/packages/preset/agent-presets/tests/fixtures/plugins/contribute.js
@@ -17,4 +17,9 @@ export function apply(ctx, config) {
     order: 10,
     text: `section for ${config.tool}`,
   }))
+  // Reconfiguring a live row runs the Loader's `internal/update` waterfall,
+  // which persists the owning tree. That is the trigger reaching the preset
+  // tree's `write` while the subtree is still mounted; tearing the agent down
+  // instead stops earlier, in the loader's own "tree is being disposed" case.
+  globalThis.__RECONFIGURE__ = tool => ctx.fiber.update({ ...config, tool })
 }
diff --git a/packages/preset/agent-presets/tests/mount.spec.ts b/packages/preset/agent-presets/tests/mount.spec.ts
index 93b77d0047..fb3bfb6d8a 100644
--- a/packages/preset/agent-presets/tests/mount.spec.ts
+++ b/packages/preset/agent-presets/tests/mount.spec.ts
@@ -219,22 +219,25 @@ describe('a roster with nothing in it', () => {
 
 describe('attributing a service to a subtree', () => {
   it('never writes the preset file back, however the subtree changes', async () => {
+    delete (globalThis as { __RECONFIGURE__?: unknown }).__RECONFIGURE__
     const handle = await ctx.agents.create({
       sessionId: SessionId('sess-write'),
       setup: async (agentCtx: Context) => void await ctx.agentPresets.mount(agentCtx, 'standard'),
     })
-    const [mount] = livePresetMounts().filter(entry => entry.presetId === 'standard')
-    expect(mount).toBeDefined()
     const file = join(FIXTURES, 'system', 'standard', 'agent.cordis.yml')
     const before = await readFile(file, 'utf8')
 
-    // The inherited `write()` persists the tree whenever the Loader thinks the
-    // config moved, and disposing an agent disposes its whole subtree — which
-    // is enough to trigger it. Inheriting that truncates the shipped preset to
-    // `[]` the first time a session ends.
-    await handle.dispose()
+    // The inherited `write()` persists the whole tree whenever the Loader
+    // decides a row's config moved, so one row reconfiguring itself would
+    // rewrite the shipped composition — here, with the row's new tool name.
+    const reconfigure = (globalThis as { __RECONFIGURE__?: (tool: string) => Promise<void> }).__RECONFIGURE__
+    expect(reconfigure).toBeTypeOf('function')
+    await reconfigure!('rewritten')
 
+    expect(toolNames(ctx, handle.agent)).toContain('rewritten')
     expect(await readFile(file, 'utf8')).toBe(before)
+
+    await handle.dispose()
   })
 
   it('attributes nothing to a subtree that is already torn down', async () => {