**Feature request**
When a chat has a plan open in the editor/panel, I want closing that plan to stick for that conversation.
**Repro**
- Open a chat that has a Plan visible (plan editor/panel open)
- Close the plan
- Switch to another chat
- Switch back to the first chat
**Expected:** plan stays closed
**Actual:** plan reopens
**Why it matters:** I close the plan to get editor space while continuing the chat. Reopening on every return is noisy and breaks focus.
**Ask:** persist per-chat dismissed/closed plan UI state (or add a setting), similar to how closed panels should stay closed until I explicitly reopen.
Related but different: chat-tab restore bugs and plans reappearing in long transcripts. This is specifically manual close → switch chat → return → plan is back.