Exiting plan mode not reliable with new GPT-5.6 models

Describe the bug

When creating a plan with the new GPT-5.6 models (doesn't matter which one), often the interaction ends like this:

Plan saved to plan.md, with implementation tasks tracked in the session database.

And then nothing happens, what is expected is that the user is prompted with how to execute this plan, but this almost never happens. What works is to do prompt something like:

Present me the plan, and ask me to implement with autopilot

And after that implementation works as expected.

Other models (GPT-5.5, Anthropic, etc) do not have this issue.

Affected version

1.0.71

Steps to reproduce the behavior

See above

Expected behavior

See above

Additional context

N/A

Es werden keine Dateien, Tests oder Einstiegspunkte genannt. Reproduziere den Fehler in Version 1.0.71 mit einem GPT-5.6-Modell, vergleiche ihn mit GPT-5.5 oder Anthropic und verfolge das Verlassen des plan-mode; als abgeschlossen gilt die Aufgabe, wenn der erwartete Implementierungs-Prompt nach dem Speichern des Plans zuverlässig erscheint.