Instruction file imported from ITU-ScrollBar/ScrollBarWebsite (.github/instructions/firebase-functions.instructions.md). Copyright stays with the author.

Firebase Functions Rules

• Keep functions/src as the editable source; generated files in functions/lib are build output only.
• Export deployable functions from functions/src/index.ts and keep module files focused on one responsibility.
• Use process.env for runtime configuration in functions code and provide safe defaults for local emulation when needed.
• Keep admin initialization guarded against duplicate init during local runs.
• Validate request inputs early and return clear HTTP status codes/messages for failures.

Firestore And Data Handling

• Query only the needed env-scoped collections and fields; avoid broad reads when narrower filters are possible.
• Normalize timestamp/date inputs defensively before generating calendar or mail payloads.
• Keep event/member mapping logic deterministic and null-safe to avoid partial payload crashes.

Shared Types And Build

• Shared types are copied from src/types/types-file.ts via the prebuild script.
• After changing shared types or function signatures, run npm run build in functions to refresh copied types and lib output.
• Keep node runtime compatibility with functions/package.json engines (node 22).