> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nomos.energy/llms.txt
> Use this file to discover all available pages before exploring further.
# Changelog
> What changed between Nomos API versions.
Each entry below corresponds to a date-based version you can pin per Auth Client or per request. See [Versioning](/api-references/versioning) for how to upgrade.
Gauss is in preview: it is reachable only by sending `X-API-Version: 2026-09-08.gauss` explicitly, is never a client's default, and may still change before it graduates.
**Breaking changes**
* `GET /plans/{id}/quote` becomes `POST /plans/{id}/quote`, [Calculate a quote](/api-reference-2026-09-08-gauss/plans/calculate-a-quote): same path, and the `GET` now returns `NOT_FOUND`. The inputs move into a body so the §14a EnWG modules travel as one `grid_fee_reductions` object, and so the response of [Calculate savings](/api-reference-2026-09-08-gauss/plans/calculate-savings) can be posted straight back. `usage` is an object there as well: send the priced kWh as `usage.consumption`, not as a plain number. On earlier versions the `GET` is unchanged.
* `meter_type` is gone. Load shifting needs a smart meter, so the quote prices one whenever the optimization rate that applies is above zero and an analog meter otherwise. That rate is `optimization_rate` when sent, and the plan's own rate when it is not, so a plan configured with a rate is quoted on a smart meter by default and `optimization_rate: 0` is how you ask for an analog one.
* [Calculate a quote](/api-reference-2026-09-08-gauss/plans/calculate-a-quote) states the load-shifting discount on a subcomponent of its own (`subgroup: "optimization"`, a negative amount) instead of folding it into `energy`. `energy` is now the undiscounted EPEX day-ahead average; the subcomponents still sum to `unit_amount` and the quote total is unchanged. Clients that read `energy` as the billed energy price should read the two rows together, or keep pinning `2026-05-27.curie`.
* Both new endpoints are a `POST`, so they need a `write:*` token even though they read and change nothing: the required scope follows the HTTP method, not the effect.
**New features**
* [Retrieve spot prices](/api-reference-2026-09-08-gauss/prices/retrieve-spot-prices) adds `GET /spot-prices`, independent of a subscription. Select raw realized German EPEX prices with `type=day_ahead` (the default), or Nomos's forecast of that market price with `type=day_ahead_forecast`. Both use the familiar price time-series envelope in `ct/kWh`, with no subscription, components, fees, margins, VAT, taxes or levies. The response lists every interval start without a published price under `missing`, so an unpublished day or a partial multi-day response is detectable without counting intervals. Partner integrations use their existing read access; forecasts require separate partner enablement, cover yesterday through seven days ahead, and retain the curve frozen before delivery. Realized prices can be requested for any past date through tomorrow. Subscription prices are unchanged.
* [Calculate a quote](/api-reference-2026-09-08-gauss/plans/calculate-a-quote) takes an optional `optimization_rate`, the share of the day-ahead price load shifting is expected to save. Omit it for the plan's own rate (a plan that configures none is quoted without optimization), or send a number to override it, with `0` pricing the plan without any optimization. Feed-in plans never earn an optimization row, whatever is sent. Where there is no discount to state the `optimization` subcomponent is absent rather than zero.
* `grid_fee_reductions` adds `14a_module_3` (Zeitvariable Netzentgelte) to the two modules already supported. With it the `grid` subcomponent is the operator's low, standard and high windows blended over the share of the year the schedule is in effect, rather than the static rate. It requires `14a_module_1`, and the blended rate can exceed the static one, in which case the grid line goes up.
* The quote response carries `resolution`, the period its amounts cover. It is `month` today, matching every earlier version.
* [Calculate savings](/api-reference-2026-09-08-gauss/plans/calculate-savings) estimates what a household saves per year on a plan, broken down into the tariff, the §14a EnWG grid fee reductions, and optimization. Describe the household in the body by its base `household.usage` plus one object per asset it owns under `assets` (`ev`, `heatpump`, `pv`, `battery`), with an optional `current_tariff` (`base_fee` in EUR per year, `var_fee` in EUR per kWh) to compare against instead of the market benchmark. The optimization rate and the §14a EnWG eligibility are derived from that mix and from what the plan sells; they cannot be requested. Post `usage`, `optimization_rate` and `grid_fee_reductions` from the response back to Calculate a quote unchanged to price the same household and reconcile every figure.
Curie introduces feed-in support, improved smart meter orders, webhook events, the first `PATCH` endpoints, and restructures key resources around top-level endpoints. Older versions keep the removed routes and previous response shapes.
**Breaking changes**
Several routes are replaced by top-level endpoints. The old routes are removed from this version onwards:
| Old route | Replacement |
| ----------------------------------------- | ------------------------------- |
| `GET /subscriptions/{id}/invoices` | `GET /invoices` |
| `GET /subscriptions/{id}/meter_readings` | `GET /meter-readings` |
| `POST /subscriptions/{id}/meter_readings` | `POST /meter-readings` |
| `GET /suppliers`, `GET /suppliers/search` | `GET /market-partners` |
| `GET /subscriptions/{id}/consumption` | `GET /subscriptions/{id}/usage` |
Scope the new list endpoints to a single subscription with `filter[subscription][eq]=`
* The [Retrieve usage data](/api-reference/usage/retrieve-usage-data) response `object` field changes from `consumption` to `usage`.
* Meter order responses collapse `status` from 14 internal partner-specific states to 8 public values and drop `updated_at`; see [Retrieve a smart meter order](/api-reference/smart-meter-orders/retrieve-a-smart-meter-order) for the full list. `POST /meter-orders` is unchanged.
**New features**
* [Feed-in](/guides/feed-in) plans compensate customers for electricity they feed into the grid, for example from rooftop solar. Plans and subscriptions carry a `type` field (`consumption` or `feed_in`).
* `POST /subscriptions/{id}/terminate` terminates a subscription via a discriminated `reason` field: `ORDINARY`, `MOVE_OUT`, or `WITHDRAWAL`.
* `PATCH /subscriptions/{id}` updates the billing address, payment method, or metadata.
* `PATCH /customers/{id}` updates the customer's name.
* Meter orders report lifecycle timestamps and reasons for cancelled or blocked orders.
* Invoices add support for prepayments and voided invoices via new `type` values (`prepayment`, `void`) and statuses (`voided`, `uncollectible`).
* [Structured validation errors](/api-references/errors): failures return an `errors[]` array with one entry per invalid field instead of a single message.
* [Webhook events](/webhooks/introduction) for invoices and smart meter orders.
Edison adds grid fee reductions for §14a EnWG modules, smart meter orders, and filtering on all list endpoints.
**New features**
* `GET /grid-fee-reductions`, `GET /grid-fee-reductions/{id}`, and `POST /grid-fee-reductions` manage grid fee reductions for §14a EnWG modules.
* `GET /meter-orders`, `GET /meter-orders/{id}`, and `POST /meter-orders` manage smart meter orders for a subscription.
* All list endpoints support [Filtering](/api-references/filtering).
Batman introduces pagination on all list endpoints and API versioning.
**Breaking changes**
* List endpoints are paginated. See [Pagination](/api-references/pagination). Affects `/customers`, `/leads`, `/plans`, `/subscriptions`, `/subscriptions/{id}/invoices`, `/subscriptions/{id}/meter_readings`, `/suppliers`, and `/suppliers/search`.
**New features**
* [Versioning](/api-references/versioning). Routes stay the same; pin a version per Auth Client or per request via `X-API-Version`.
Initial public version of the Nomos API.