Document branch workflow expectation

AGENTS.md

@@ -5,6 +5,7 @@
 - When updating `PROGRESS.md`, add a date marker (e.g., `## YYYY-MM-DD — …`) and list changes under it until the date changes; keep earlier entries intact and sorted by date.
 - After that, scan the repo structure (e.g., list key dirs/files) to regain context before continuing work.
 - After finishing each new feature, create a git commit with a sensible message and update documentation to reflect the changes.
+- Always assume work should continue on a feature or fix branch; if unsure whether to reuse a previous branch (which might already be pushed and deleted), ask before proceeding.
 
 ## Ongoing reminders
 - If needed, render diagrams locally from `docs/plantuml` or `docs/drawio` for reference.