feat(euclid): integration with decision engine

[prajjwalkumar17]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates
• Documentation
• CI/CD

Description

This PR integrates the Euclid-based decision engine with Hyperswitch’s dynamic routing infrastructure. It enables dual routing logic: legacy DSL-based evaluation and decision-engine-backed configurations. The integration ensures routing algorithms can be authored, activated, and evaluated via Euclid and linked seamlessly to merchant profiles.

Outcomes

• Adds support for storing and linking decision-engine routing IDs (decision_engine_routing_id) in the existing routing_algorithm table.
• Enables creation and linking of Euclid routing configurations during algorithm creation and configuration linking flows.
• Enhances observability with logging and tracing of decision engine interactions.
• Preserves backward compatibility with existing static/dynamic routing mechanisms.

Diff Hunk Explanation

crates/api_models/src/routing.rs

• Added decision_engine_routing_id to RoutingDictionaryRecord to expose the DE mapping in API responses.
• Updated RoutingAlgorithmKind with PartialEq to aid in logic branching.

crates/diesel_models/src/routing_algorithm.rs

• Included new optional field decision_engine_routing_id to map to Euclid's algorithm record.

crates/diesel_models/src/schema.rs

• Altered routing_algorithm schema to include decision_engine_routing_id VARCHAR(64).

crates/router/src/core/payments/routing.rs

• Imported perform_decision_euclid_routing into static routing flow for test execution and future use.

crates/router/src/core/routing.rs

• On routing creation, checks if the algorithm is a Euclid (Advanced) type, then creates it in the decision engine and stores the returned ID.
• On routing configuration linking, activates the respective routing config in the decision engine using ActivateRoutingConfigRequest.
• Enhances retrieve_merchant_routing_dictionary to fetch and append decision engine routing configs by profile ID.

crates/router/src/core/routing/transformers.rs

• Ensures decision_engine_routing_id is preserved and transformed when converting between internal and API models.

migrations/2025-05-08-102850_add_de_euclid_id_in_routing_algorithm_table/*.sql

• Adds and removes the decision_engine_routing_id column in the routing_algorithm table via Diesel migrations.

Additional Changes

• This PR modifies the API contract
• This PR modifies the database schema
• This PR modifies application configuration/environment variables

Motivation and Context

How did you test it?

Here is the complete testing guidelines.

Migrations

ALTER TABLE routing_algorithm
ADD COLUMN decision_engine_routing_id VARCHAR(64);

Checklist

• I formatted the code cargo +nightly fmt --all
• I addressed lints thrown by cargo clippy
• I reviewed the submitted code
• I added unit tests for my changes where possible

[semanticdiff-com]

Review changes with  

Changed Files

File	Status
crates/api_models/src/routing.rs	78% smaller
crates/router/src/core/routing.rs	11% smaller
crates/router/src/core/payments/routing.rs	8% smaller
api-reference-v2/openapi_spec.json	0% smaller
api-reference/openapi_spec.json	0% smaller
crates/diesel_models/src/routing_algorithm.rs	0% smaller
crates/diesel_models/src/schema.rs	0% smaller
crates/router/src/core/payments/routing/utils.rs	0% smaller
crates/router/src/core/routing/helpers.rs	0% smaller
crates/router/src/core/routing/transformers.rs	0% smaller
migrations/2025-05-08-102850_add_de_euclid_id_in_routing_algorithm_table/down.sql	Unsupported file format
migrations/2025-05-08-102850_add_de_euclid_id_in_routing_algorithm_table/up.sql	Unsupported file format
v2_migrations/2025-01-13-081847_drop_v1_columns/up.sql	Unsupported file format

[Sarthak1799]

Migration tests failing @prajjwalkumar17
Also fix the migration in PR desc, those should be to add the column.

[jagan-jaya]

Add an alter table command in v2_migrations/2025-01-13-081847_drop_v1_columns/up.sql to remove the decision_engine_routing_id column in routing_algorithm.

Otherwise create down.sql also