Changelog

Changed

• Production status. auth.messpunkt.io, api.messpunkt.io and mcp.messpunkt.io have been live since 2026-09-30 against real data. ERP clients are registered on request; API access is enabled per customer organisation. Pages, spec and llms.txt no longer say that production goes live with the first pilot partner.
• external_ref (field and filter) and obis are described as not supported today, without a release promise. The field stays in the contract and is always null; a non-empty external_ref filter returns an empty page.
• ERP guide: resource — an ERP client that omits it gets a token for the REST API; send it anyway. The spec no longer claims the sandbox consent screen pre-selects nothing: all Properties is pre-selected.

Changed

• DPoP is supported and optional (was "required in production"). A token obtained with a DPoP proof is bound to your key and must then always be sent with a valid proof; plain bearer tokens work otherwise. DPoP can be made mandatory per registered client on request.
• Consent: the landlord chooses all Properties, including future ones (property_scope: "all") or a selection. Disconnecting in the portal takes effect within 60 seconds; changing the selection means reconnecting. The previously described in-place scope editing is not offered.
• Authentication section documents resource (RFC 8707), iss in the authorization response (RFC 9207), /oauth/revoke (RFC 7009), registered ERP clients (private_key_jwt, client_secret_basic) and the per-Tenant API activation.
• Canonical model corrected: measuring points hang off a Sector under the Address, and Sectors are allocated to UsageUnits — not UsageUnit → Sector as drawn before.
• ReadingStatus no longer claims to map 1:1 to an internal type; each value is described by what it means.
• linear_interpolation / degree_day_weighted now describe how calculated month-end values were interpolated.
• Rate limits clarified and published, the same in production and sandbox: /v1/* 300 requests/min per connection (grant, the token's sid), counted after the token is validated, requests whose token fails validation per caller address; /oauth/token and /oauth/revoke 60/min per client_id after successful client authentication, in addition 60/min per caller address; /oauth/authorize 60/min per caller address; the MCP server 60/min per connection. 429 with Retry-After; counted in memory per server instance (best effort). rc.2 said "per client_id" in one place and "per caller IP" in another; neither described /v1/*, which is counted per connection because one ERP system serves many landlords from one address.
• Examples use fictional addresses (Musterstraße, Musterstadt) and unit labels without names.

Migration from rc.2

• Parse MeterReading.at as a date; do not expect exactly two readings per segment.
• Bill the sum of period_consumption.billable_value per measuring point; never bill a segment whose status is calibration_expired or missing.
• Handle installed_at: null; do not replace it with a date of your own.
• Handle usage_unit_id: null; read the total meters of a plant room from GET /properties/{id}/measuring-points.
• Handle active_device: null and measuring points with is_difference_meter: true and no segments.
• Keep water_outdoor out of residents' water; tolerate unknown enum values from now on.
• Stop relying on obis, resolution and external_ref.
• The sandbox keeps serving the rc.2 shape until its rc.3 update, which will be announced here.

rc.3 — Clarifications (not breaking)

Documentation of the same rc.3 contract, written down while building the rc.3 sandbox. No field, type or enum value changed, so the version number stays 1.0.0-rc.3.

• Errors: GET /properties and GET /usage-units document 400 invalid-request for an invalid limit, page_cursor or property_id. A consumption range that lies entirely after the last completed month is 400, and so is an unknown metric value (named in detail). Every operation now lists 500 internal-error and 503 service-unavailable — no detail, retry with backoff.
• /whoami answers 401 invalid-token when the landlord's API access has ended — never 404.
• Device removed inside the range: period_consumption.end_value is the value on the removal day, status measured; if the removal day is a month end, the value also appears as that month's reading.
• Unknown installation date: baseline_date is the month-end before from if known, otherwise the first known value — which can lie inside the range, not only before from.
• No value at the end of the range: nothing is carried forward from an earlier month; unless the value is substituted, period_consumption.status is missing.
• token_expires_at is omitted when unknown, never null.
• Shared Sectors: how measuring points of a Sector shared by several UsageUnits appear under usage_unit_id will be fixed before GA.
• Sandbox: the data is static up to 2026-12-31, and the fixture contains no substituted values.

rc.3 — Addendum: error type and smaller corrections

Changed before rc.3 is published, so the version number stays 1.0.0-rc.3.

• Problem type is now https://developer.messpunkt.io/errors/#<code>, the same in sandbox and production, and each value opens the explanation on Error handling. It used to be https://api(.sandbox).messpunkt.io/errors/<code>, an address where no page lives. The codes are unchanged. Action: branch on the fragment after # instead of the last path segment. The authorization server's 429 uses the same form.
• 404 resource-not-found is also the answer for an {id} in the path that is not a UUID. It used to be an empty 404 without application/problem+json.
• Property.addresses lists every address of the Property, including addresses without usage units; before, only addresses that carried a unit appeared.
• Error texts: 403 says how to get the missing scope; an invalid date echoes the value (from must be an ISO 8601 date (yyyy-MM-dd); got '2025-13-01'.). detail stays free text — do not parse it.

rc.3 — Addendum: changed meaning (shared Sectors)

rc.3 said that values are “per device and never pre-weighted” and left open how a measuring point of a Sector shared by several usage units appears. messpunkt.io has such Sectors in production — 46 partial allocations, with 12 Sectors split between three to five units each — so the open point is now fixed:

• MeasuringPoint.usage_unit_id is the primary unit (highest share; tie: the smallest id). allocations[] lists every unit with its share.
• The measuring point is listed under every unit with a share, with that unit's unit_share. Before, rc.3 did not say that one measuring point can appear under several units.
• Device values stay unweighted (readings, value, billable_value). The number to bill for a unit is now weighted_billable_value — the same weighting as the residents' portal; summed over the units of a Sector it gives the Sector's consumption, so a shared meter is never billed twice.
• Action: sum weighted_billable_value (fall back to billable_value while it is absent) when you bill a unit. A client that keeps summing billable_value per unit bills a shared meter in full to every unit that shares it.

Changed

• Sandbox tenant renamed from Hausverwaltung Musterfrau GmbH to Musterhausverwaltung GmbH — clearer, more business-like, still unambiguously fictional
• Sandbox consent screen fully redesigned: German UX, action-verb permission descriptions, "Select all" Properties toggle, signed-in avatar, trust-building footer about revoke
• Device serials are now pure numeric (8–10 digits) matching real WMBus format; manufacturer field remains the sole source of brand identity
• Fixture addresses now use 34 realistic German street names across 14 mid-sized cities (Potsdam, Leipzig, Dresden, Hannover, Stuttgart, Freiburg, Kiel, Münster, Bremen, Erfurt, Augsburg, Karlsruhe, Regensburg, Nürnberg)

Changed

• Version bumped from 0.1.0-draft to 1.0.0-rc.1; formal stability contract documented in the Reference
• Bumped Scalar CDN to @1.52.2 (fixes OAuth scope-preselect bug upstream)