docs: decision record about common expression language adoption

docs/developer/decision-records/2026-01-27-adopt-cel-expressions/README.md

@@ -0,0 +1,44 @@
+# Adopt CEL Expressions for Policy Evaluation
+
+## Decision
+
+The experimental work on Common Expression Language (CEL) for evaluating policy expressions will be adopted as a
+first-class feature of EDC core. This means that users will be able to define and evaluate policies using CEL
+expressions without requiring custom Java code for policy functions.
+
+## Rationale
+
+Integrating CEL into EDC core offers several advantages:
+
+1. **User-Friendly Policy Definition**: CEL provides a more accessible way for users to define policies dynamically,
+   reducing the need for Java coding skills.
+2. **Flexibility**: CEL allows for more complex and nuanced policy definitions that can adapt to changing requirements
+   without redeploying the EDC runtime.
+3. **Performance**: CEL is designed for efficiency, ensuring that policy evaluations remain performant even with complex
+   expressions.
+4. **Standardization**: Adopting CEL aligns EDC with a widely recognized expression language, promoting consistency and
+   interoperability.
+
+## Approach
+
+The original design document is
+available [here](https://github.com/eclipse-edc/Virtual-Connector/blob/main/docs/common_expression_language.md) and
+outlines the integration of CEL into EDC platform.
+
+Here's the recap of the approach:
+
+1. **CelExpression** Entity: Introduce a new entity to represent CEL expressions associated with atomic constraints.
+2. **CelExpressionStore**: Implement a store to manage the persistence of CelExpression entities.
+3. **CelExpressionService**: Create a service to handle the creation, retrieval, updating, and deletion of CelExpression
+   entities.
+4. **CelExpressionEngine**: Develop an engine that utilizes the CEL Java library to evaluate CEL expressions during
+   policy evaluation.
+5. **Policy Function Integration**: Implement a custom policy function that leverages the `CelExpressionEngine` for
+   evaluating policies using CEL syntax.
+
+The CEL based policy evaluation will be integrated alongside existing Java-based policy functions,
+and will still be experimental until stabilized in future releases. It will not be included
+in the default BOMs at first, and users will need to explicitly include the CEL extension to use this feature.
+
+The Management API for CEL expressions won't be ported at first to EDC core, they will be ported after the stabilization
+of the current `v4beta` release of the Management API.

docs/developer/decision-records/README.md

@@ -91,3 +91,4 @@
 - [2025-10-29 Participant identifiers resolution](2025-10-29-participant-identifiers)
 - [2025-11-10 Extracting service for presentation requests](2025-11-10-presentation-request-service)
 - [2026-01-08 inline DataFlowManager](2026-01-08-inline-data-flow-manager)
+- [2026-01-27 Adopt CEL expressions](2026-01-27-adopt-cel-expressions)