name: functions-local-dev description: Runs and troubleshoots the Azure Functions backend locally (build/watch/func host start, local.settings modes). Use when developing or debugging backend HTTP/queue functions.

Functions local dev

Use this skill when you are asked to:

•Start the backend Functions host locally.
•Switch local persistence modes (memory vs cosmos).
•Debug common “func won’t start” / config issues.

Canonical local loop

Preferred options:

•
VS Code tasks (recommended):
- •npm watch (functions)
- •func: host start
•
Single command dev loop:
- •npm run dev in backend/

Helper scripts

•scripts/start-backend-dev.mjs — starts backend dev loop with a stable entrypoint.

Environment notes

•Backend expects local.settings.json in backend/.
•
Use the existing npm helpers:
- •npm run use:memory (backend)
- •npm run use:cosmos (backend)

If Azure Functions Core Tools (func) isn’t installed, the host start step will fail; prefer VS Code task output for diagnosis.

Last reviewed: 2026-01-15