Services

In one line

Six service-* features. Each is driven by direct method calls or a client builder attachment, never by plugin hooks.

You need

The service features you want, named explicitly. None is enabled by default.

Read this if

You need a service's feature flag, entry type, plugin dependency, configuration, caps or errors.

The six features

Service tier rules

• A service is an explicit-call, client-level capability. The caller drives it with method calls, or attaches it to a client builder (with_orchestrator, with_prompt_cache_config, with_prompt_cache_service).
• A service never implements CucaPlugin. Passing one to register_plugin is a compile error, not an inert registration.
• A service may depend on core and on the plugin features it declares in Cargo.toml. A plugin never names a service: no use, no cfg(feature = "service-..."), no feature edge, no runtime lookup.
• Every code edge from a service to a plugin is declared as service-<name> = ["plugin-<other>"].
• No service depends on another service.
• Plugins and services do not look each other up at runtime. Data crosses tiers through a caller-injected Arc<dyn Trait> or an explicit hand-off by the application.
• Each service feature builds alone on one provider. The service_solo CI job checks it.

Plugins and services explains why the tiers are shaped this way.

Feature edges to the plugin tier

Cargo.toml declares three hard edges, all from a service to a plugin:

service-entity-extraction = ["plugin-memory"]
service-replay = ["plugin-session-log"]
service-vector-store = ["plugin-memory", "dep:wide"]

• entity-extraction to memory, hard: the extraction delta is a MemoryGraph that the caller merges into the memory plugin's working graph.
• replay to session-log, hard: replay reads a recorded trajectory through the session log's SessionBackend seam.
• vector-store to memory, hard: the store implements the memory plugin's VectorStore offload seam, wired through MemoryPlugin::with_extensions, and hands recalled turns back through RetrievalReport::inject.
• speculative to session-log, documented-optional: it declares no feature edge. ModelOrchestrator::with_session_store exists only when plugin-session-log is also enabled, and records SessionEvent::ModelSwap.
• prompt-cache and rate-limit declare no plugin dependency.

Page layout

Every service page uses the same headings, in this order:

1. Feature and entry type
2. Entry points
3. Configuration
4. Caps and at-cap policy
5. Errors
6. Example
7. Related pages

The consolidated view of every cap, across plugins and services, is Memory discipline.