docs: Add decision record for DID document based connector discovery

docs/development/decision-records/2026-01-06_service_retrieval_from_did_document/README.md

@@ -0,0 +1,86 @@
+# Connector endpoint retrieval from DID Document service section
+
+## Decision
+
+We will implement an additional endpoint in the connector discovery endpoint family. The endpoint will, based on a
+DID retrieves the DID document, parses the service section for `DataService` entries, and retrieves for the detected
+connector endpoints the dsp version parameters. It returns a list of version parameter sets for all found connectors
+in the DID document. There will be a general support for other identifiers, using BPNLs as a second supported
+identifier type.
+
+## Rationale
+
+The current Tractus-X connector supports multiple versions of the DSP protocol the ones supported published
+in the `.well-known/dspace-version`
+[endpoint](https://eclipse-dataspace-protocol-base.github.io/DataspaceProtocol/2025-1/#exposure-of-dataspace-protocol-versions).
+In addition, the DSP spec suggests to use the
+[DID document](https://eclipse-dataspace-protocol-base.github.io/DataspaceProtocol/2025-1/#discovery-of-service-endpoints)
+to publish connector endpoints. With this feature, the Tractus-X connector is about to support this retrieval of
+connector endpoints together with the detection of the right version parameters used in the management api to
+initiate DSP calls in the right version.
+
+As for multi version connectors, only the option to use a `DataService` reference in the DID document makes sense,
+the discovery of endpoints is limited to this type of connector references.
+
+## Approach
+
+There is already a 
+[connector discovery extension](https://github.com/eclipse-tractusx/tractusx-edc/blob/eaa7084e83912e6dae42c13c948607a68d85ffa7/edc-extensions/connector-discovery/connector-discovery-api) 
+that implements the retrieval of the `.well-known/dspace-version` endpoint and to create the proper dsp version
+parameters for a single connector endpoint provided as parameter. There is a second extension there which provides
+a default implementation of the defined api.
+
+As the intended api is related to this functionality, the approach is, to add another management api endpoint
+called `/connectors` in this management api section that takes the following input parameters:
+
+```json
+{
+  "identifier": "did:web:",
+  "knowns": [
+    "https://first.provider-domain.com/somepath/dsp/v1/api",
+    "https://first.provider-domain.com/otherpath/dsp/v1/api",
+    "https://second.provider-domain.com/dsp/v1/api"
+  ]
+}
+```
+
+The identifier field is kept neutral, in order to support different identifier types. The service will interpret
+the identifier based on properties of the identifier, for now, DIDs and BPNLs will be supported. The mechanism
+will be implemented in an extensible fashion, so that a general mapping from any identifier to a DID can be added.
+The default implementation will detect DIDs and map them to themselves. A second extension will allow to handle
+BPNLs and map them to the DID using the BDRS client.
+
+The second input parameter `knowns` is optional and allows to add already known connector endpoints, so that also
+for such them the version discovery can be executed and the right management api parameters are determined.
+
+Consequently, the response has a body like this:
+
+```json
+[
+  {
+    "counterPartyAddress": "https://provider-domain/somepath/dsp/v1/api/2025-1",
+    "counterPartyId": "did:web:...",
+    "protocol": "dataspace-protocol-http:2025-1"
+  },
+  {
+    "counterPartyAddress": "https://other-provider-domain/otherpath/dsp/v1/api",
+    "counterPartyId": "BPNL...",
+    "protocol": "dataspace-protocol-http"
+  }
+]
+```
+
+So it returns a list of parameter sets for the listed connectors in the DID document. It adds the known connectors
+given as input and also requests the central discovery for now and provides the list of connectors from there.
+
+The algorithm will make use of the existing features to download the DID document as well as the `dspace-version`
+endpoint and processes the information. In case of a BPNL provided, it makes use of the BDRS client to translate
+the BPNL to the DID.
+
+## NOTICE
+
+This work is licensed under the [CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/legalcode).
+
+- SPDX-License-Identifier: CC-BY-4.0
+- SPDX-FileCopyrightText: 2026 Cofinity-X GmbH
+- Source URL: [https://github.com/eclipse-tractusx/tractusx-edc](https://github.com/eclipse-tractusx/tractusx-edc)