# Description
Introduces a pluggable user-identity provider model covering all OPC UA
Part 6 §6.5 mechanisms (Anonymous, UserName, X509, IssuedToken/JWT) on
both client and server, with full
`Microsoft.Extensions.DependencyInjection` integration, plus the Part 12
§9 `AuthorizationService` two-phase token-request flow **including
refresh-token rotation**, the Part 12 §8 KeyCredential Push model, and a
clean provider model for OPC 10000-12 §7.2 `ApplicationSelfAdmin`. The
work is split across phase-by-phase commits so it can be reviewed
independently; nothing here changes wire-level behaviour or forces
existing applications to migrate.
### Documentation
All under `Docs/`:
- `IdentityProviders.md` — full developer guide: three-layer model,
recipes, configuration reference, "what gets auto-wired" matrix, JWS
algorithm table, identity-augmenters section, **"Implementing your own
provider"** how-to subsections for Entra / OIDC / Windows / AspNetCore
(sibling files merged in per review feedback).
- `DependencyInjection.md` — `Identity` sections with `appsettings.json`
examples, identity-extension matrix, `WithAuthorizationService` +
`WithKeyCredentialPush` + `AddIdentityAugmenter` extensions documented.
- `RoleBasedUserManagement.md` — claim-criteria callout describing
`IIdentityClaims` probe surface.
- `AuthorizationService.md` — Architecture diagram +
`IAccessTokenProvider` conceptual narrative restored from master; modern
`StartRequestToken` / `FinishRequestToken` flow leads; refresh-token
recipe added.
- `KeyCredentialService.md` — Push model + Pull vs Push vs Bridge
decision matrix + Hybrid (Push + Pull) section; explicit experimental
warning for the bridge.
- `GDS.md` — KeyCredential Push, `StartRequestToken`,
`GdsApplicationSelfAdminProvider`, **shipped Refresh-token support with
rotation policy and audit semantics** all documented.
- `MigrationGuide.md` — User Identity Providers section listing
`[Obsolete]` markers + mechanical recipes; SelfAdmin migration via
`IIdentityAugmenter`; `EnableRefreshTokens` default note.
- `README.md` index entries.
## Checklist
- [x] I have signed the
[CLA](https://opcfoundation.org/license/cla/ContributorLicenseAgreementv1.0.pdf)
and read the
[CONTRIBUTING](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/CONTRIBUTING.md)
doc.
- [x] I have added tests that prove my fix is effective or that my
feature works and increased code coverage.
- [x] I have added all necessary documentation.
- [x] I have verified that my changes do not introduce (new) build or
analyzer warnings.
- [x] I ran **all** tests locally using the **UA.slnx** solution against
at least .net **framework** and .net **10**, and all passed.
- [x] I fixed **all** failing and flaky tests in the CI pipelines and
**all** CodeQL warnings.
- [x] I have addressed **all** PR feedback received.
Marc Schier