> ## Documentation Index
> Fetch the complete documentation index at: https://docs.useharmonia.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Environment variable reference

> Index of Harmonia configuration domains and the source files that validate them.

Use `.env.example` as the value-level template and [Configuration](/configuration) for setup instructions. `src/lib/config.ts` validates web and budget configuration; `agent/harmonia_agent/config.py` validates worker settings.

| Domain                 | Purpose                                      | Typical requirement                |
| ---------------------- | -------------------------------------------- | ---------------------------------- |
| Firebase and Firestore | Operator sessions and durable tenant data    | Required outside local emulators   |
| Google Cloud           | Project, region, storage, Pub/Sub, Cloud Run | Required for cloud runtime         |
| Gemini / Vertex AI     | Agent and media model access                 | Required for real model calls      |
| Internal service auth  | Web-to-worker and scheduler authentication   | Required outside local development |
| X                      | OAuth and official API publishing/read-back  | Only when X is enabled             |
| Telegram               | Bot webhook and allow-listed chat            | Only when Telegram is enabled      |
| Google Calendar        | OAuth client and redirect configuration      | Only for explicit calendar sync    |
| Budgets and models     | Catalog, ceilings, approval thresholds       | Required for paid operations       |

Secrets belong in server-side environment injection or Secret Manager. Never expose them through `NEXT_PUBLIC_*`, documentation, logs, or evidence artifacts.