Plugins, Decisioners, and MCP tools

Choose a plugin kind

Each sidecar process runs one plugin kind and implements riptide.ext.v1.ExtensionService with Describe, Health and Invoke. The archive's README maps each kind to its command, JSON payload, expected output and conformance test.

Declare name, version, kind, entitlement, health behavior, a latency budget and a config schema. Serve-path budgets must be positive and at most 50 ms; aggregate extension budgets also need to fit the auction deadline. Honor cancellation and avoid network work beyond that budget. Declare only the request keys you need in config_schema.context_fields; receive per-tenant configuration through tenant_config. Money remains decimal strings, such as "2.5000".

The bundled policies use a local -config file and do not inspect tenant_config. Run separate instances for tenants with different policies, or implement and test tenant-config handling when adapting the starter. An installation's config_json selects host behavior such as renderer media; it does not automatically override the starter's process policy.

Build report clients against the reporting catalog, and register Decisioners through the model workflow below. The retired REPORT_FIELD and DECISIONER ExtensionService kinds are rejected on new listings. Adding a stored report dimension requires a schema and catalog change in a customer checkout.

Decisioners: register a model and start in shadow

A Decisioner preserves a deterministic baseline and evaluates an optional candidate. BASELINE uses platform behavior, SIDECAR uses the separate gRPC DecisionService, and EXTERNAL_ENDPOINT accepts protojson DecideRequest over HTTP. The HTTP example implements a floor policy. Measure its effect on your traffic in shadow mode before considering promotion.

Deploy the HTTP starter behind public HTTPS with a valid certificate. The serving host rejects plain HTTP, loopback and private-network HTTP destinations. Replace the example hostname below, then call createModel at POST /v1/tenants/{tenant_id}/models with an idempotency key:

{
  "decision_point": "floor",
  "name": "my-floor-policy",
  "version": "1.0.0",
  "kind": "EXTERNAL_ENDPOINT",
  "config": {
    "url": "https://decisioner.example.com/decide"
  }
}

Use the returned model ID with assignModel at POST /v1/tenants/{tenant_id}/models/{model_id}/assignments:

{"decision_point":"floor","mode":"SHADOW","traffic_pct":"100.0000"}

SHADOW measures the candidate while baseline decisions serve. Review decision records and record an evaluation using recordEvaluationRun. Promotion through promoteModel (MCP riptide.model.promote_decisioner) requires the platform operator and measured evidence before bounded A/B or live use. Failure or timeout falls back to the baseline. Tenant creation/assignment/evaluation requires model.write; it does not grant model.promote.