# Provider Account Balance

`llm_connect.balance` reports **prepaid / key remaining** for a selected
inference **backend**. Balance is never assumed to be OpenRouter unless that
backend is selected (explicitly or as the current default provider).

## Selection rules

```python
from llm_connect import get_account_balance, resolve_balance_provider

resolve_balance_provider(None)           # → LLMConfig().provider (today openrouter)
resolve_balance_provider("openrouter")   # one-shot; does not mutate defaults
get_account_balance()                    # default backend
get_account_balance("openrouter")        # explicit backend for this call only
```

- Explicit `provider` / CLI `--provider` is **invocation-only**.
- It must not rewrite config files, env, `LLMConfig` class defaults, or
  OpenRouter model defaults.
- Unspecified → current default provider via `resolve_balance_provider(None)`.

## Contract

- `AccountBalance` carries optional wallet fields (`credits_*`) and optional
  key-limit fields (`limit`, `limit_remaining`, `limit_reset`, `usage`).
- EUR display fields use the same FX resolution as cost estimates.
- `BalanceClientRegistry` maps provider id → client factory.
- Unsupported providers raise `LLMBalanceUnsupportedError` listing supported
  backends (do not fall back to OpenRouter).

## OpenRouter (v1)

- `GET /api/v1/credits` → account prepaid: remaining = total_credits − total_usage
- `GET /api/v1/auth/key` → key limit remaining / reset policy
- Both are fetched best-effort; one may fail while the other succeeds.

## CLI

```bash
llm-connect balance
llm-connect balance --provider openrouter
llm-connect balance --json
```