Glossary

Cross-cutting definitions used throughout the documentation. Terms are grouped by concern; within a group they read top-down from the most fundamental.

Platform & planes

Meridian — the clinical-workflow automation platform: an empty engine plus a plugin system that contributes all clinical vocabulary and behavior.
Engine (core) — @meridian/engine-core: the generic interpreter, the meta type-system, and the dataflow primitives. It contains no clinical content.
SDK — @meridian/shared: the stable contract a plugin compiles against (manifest schemas, the behavior/adapter/source contracts, the type system).
Configuration plane — the config-plane app: where workflows are designed, runs are monitored, agents and plugins are inspected.
Control plane — Restate: durable execution — journaling, replay, crash recovery, human-in-the-loop suspension.
Execution plane — the engine plus the ports it drives (FHIR, LLM, …), run by the Restate endpoint.

Plugins

Plugin — a self-contained package that contributes vocabulary and behavior through a single plugin.yaml manifest. Loaded by the host; never a build-time dependency of the engine.
Manifest (plugin.yaml) — a plugin's declaration of everything it contributes: value-sets, dimensions, types, conversions, nodes, adapters, agents, event sources and bindings.
Contribution point — one of the manifest's declarable kinds (see above).
dependsOn — a plugin's declared dependency on another plugin, used for load ordering and cross-plugin type resolution.
Registry — a version store for published plugins (a GCS bucket or a directory), laid out @publisher/name/<version>/… with immutable versions.
SDK range (sdk:) — the SDK version a plugin requires; the host refuses and logs a plugin incompatible with its own SDK version.

Type system

TypeRef — the recursive description of a data shape: primitive, coded, quantity, object, ref, list, or any.
Value-set — a terminology backing a coded value (an enumerated code system, or an external one resolved by a terminology port).
Dimension — a physical dimension backing a quantity value (a canonical UCUM unit plus conversion factors).
Object type — a structured datatype or clinical resource, declared with typed field descriptors.
Conversion — a declarative From → Into rule between two types.

Workflows

Workflow — a declarative YAML graph (meridian/v3) of nodes wired port-to-port; the single source of truth for a process, versioned in git.
Node — a building block with typed input/output ports and a kind (trigger, source, sink, compute, gateway, human-task, agent, transform).
Port — a typed input or output socket on a node. Also, in the hexagonal sense, a contract implemented by an adapter (see below).
Connection — a typed edge nodeId.outPort → nodeId.inPort.
Trigger — the entry node that turns an inbound event into the initial context and outputs.
Context — the ambient variables a trigger establishes for a run, keyed by context kind.
Context kind — a plugin-contributed sort of ambient context (contributes.contextKinds: name, id field, ref entity) — @posos/common contributes patient, encounter, order, document. The registry is open and the core ships none.
Behavior — the JS module a node runs (its "tier C" implementation), returning outputs from inputs.
Split-pin — wiring a single object port field-by-field without an intermediate node.
after / done — the implicit flow ports every node exposes to sequence and join branches without carrying data.
Absence propagation — a required input left unfed skips the node, cutting the branch downstream — the model's "else".

Ports & adapters (hexagonal)

Port (hexagonal) — a named contract behaviors depend on. The SDK types only the ports the core calls (agent, terminology); every business port — patient record, prescription, notification, or any plugin-defined port — is defined by its owning plugin, which augments the open Ports bundle.
Adapter — a plugin's implementation of a port (e.g. a FHIR patient record, an LLM agent runner). Selected per instance. An adapter declaring record: { contextKind } is the record port of that kind (SubjectRecordPort): it serves GET /api/records/:kind/:id and receives validation publications.
Instance manifest — the deployment's concrete configuration (meridian/instance-v1): which adapter for each port, connection config, required plugins, locale.

Events & ingestion

Event source — a generic ingestion mechanism (polling, an HL7 socket…) that emits raw records, knowing nothing about domain events.
Event binding — the declarative link source + query → event + map that turns raw records into a domain event.
MapExpr — the small grammar (dotted path, JSONPath, ref, const) that maps a raw record's fields onto an event's fields.

Execution & runs

Run — one execution of a workflow, journaled and recoverable by Restate.
Run index / run-store — the proxy's queryable list of runs (SQLite or Postgres); the execution truth stays in Restate.
Human-in-the-loop (HITL) — a human-task node that suspends the run until a human decision, optionally with an SLA deadline and escalation branch.
Simulation — running a workflow spec against a forged event in a sandbox, without a durable run — the editor's "▶ Simulate".
Trace code — a structured {code, params} engine trace, translated for display (the engine persists no display language).

Internationalisation

Instance locale — the language of persisted content (validation titles, notifications). An instance is monolingual.
UI locale — the viewer's display language (cookie meridian-locale), affecting only chrome, catalog labels, and docs navigation.
Bundle (i18n/<locale>.yaml) — a plugin's translation overlay, with keys derived from the manifest structure.