“Create from PR” is using `origin/main`, not the tracked `upstream/main`.

“Create from PR” is using `origin/main`, not the tracked `upstream/main`. In my clone, `origin` points to my fork and is **294 commits behind** (because the fork's main is unused), so the diff's are crazy.

---
| Field | Value |
| --- | --- |
| App version | 1.1.8 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Day 7 (Week 1) |

Start in the desktop app's “Create from PR” flow and reproduce the issue with a fork whose origin/main is behind tracked upstream/main. Trace which remote and base branch provide the diff; the work is done when the flow uses upstream/main and produces the expected PR diff in this setup.

Written by the indexing model from the issue text.