feat(cli): add query relationship-types command

Query valid endpoint types for all relationship types. Allows users to
discover which node types are valid sources and targets for each
relationship type without trial-and-error.

Resolves issue #19

Author: Mearman

src/cli/commands/query.ts

@@ -7,6 +7,7 @@ import {
 	queryNodesOp,
 	queryNodeOp,
 	queryRelationshipsOp,
+	queryRelationshipTypesOp,
 	traceFromNodeOp,
 	timelineOp,
 	nodeHistoryOp,
@@ -245,6 +246,30 @@ const timelineSubcommand: CommandDef = {
 	},
 };
 
+const relationshipTypesSubcommand: CommandDef = {
+	name: "relationship-types",
+	description: queryRelationshipTypesOp.def.description,
+	apiLink: queryRelationshipTypesOp.def.name,
+	opts: readOpts,
+	action(_rawArgs: unknown, rawOpts: unknown) {
+		const opts = readOpts.parse(rawOpts);
+		const relTypes = queryRelationshipTypesOp({});
+		if (opts.json) {
+			console.log(JSON.stringify(relTypes, null, 2));
+		} else {
+			for (const relType of relTypes) {
+				console.log(pc.bold(relType.type));
+				console.log(
+					`  ${pc.dim("from")}: ${relType.from.map((t) => pc.cyan(t)).join(", ")}`,
+				);
+				console.log(
+					`  ${pc.dim("to")}: ${relType.to.map((t) => pc.cyan(t)).join(", ")}`,
+				);
+			}
+		}
+	},
+};
+
 const stateAtSubcommand: CommandDef = {
 	name: "state-at",
 	description: stateAtOp.def.description,
@@ -283,6 +308,7 @@ export const queryCommand: CommandDef = {
 		nodesSubcommand,
 		nodeSubcommand,
 		relsSubcommand,
+		relationshipTypesSubcommand,
 		traceSubcommand,
 		timelineSubcommand,
 		stateAtSubcommand,

src/operations/index.ts

@@ -26,6 +26,7 @@ export { planGateOp, type GateResultOutput } from "./plan-gate.js";
 export { queryNodesOp } from "./query-nodes.js";
 export { queryNodeOp, type NodeDetail } from "./query-node.js";
 export { queryRelationshipsOp } from "./query-relationships.js";
+export { queryRelationshipTypesOp } from "./query-relationship-types.js";
 export { traceFromNodeOp, type TraceNode } from "./trace-from-node.js";
 
 // Temporal operations

src/operations/query-relationship-types.ts

@@ -0,0 +1,47 @@
+import * as z from "zod";
+import { defineOperation } from "./define-operation.js";
+import { RelationshipType, NodeType } from "../schema.js";
+import { RELATIONSHIP_ENDPOINT_TYPES } from "../endpoint-types.js";
+
+/** Information about valid endpoint types for a relationship type. */
+export interface RelationshipTypeInfo {
+	type: RelationshipType;
+	from: NodeType[];
+	to: NodeType[];
+}
+
+/** Result of querying relationship endpoint types. */
+export const QueryRelationshipTypesResult = z.array(
+	z.object({
+		type: RelationshipType,
+		from: z.array(NodeType),
+		to: z.array(NodeType),
+	}),
+);
+
+/** Result type for queryRelationshipTypesOp. */
+export type QueryRelationshipTypesResult = z.infer<
+	typeof QueryRelationshipTypesResult
+>;
+
+/**
+ * Query valid endpoint types for all relationship types.
+ *
+ * Returns a list of relationship types with their valid source and target node types.
+ * Useful for discovering valid combinations before attempting to add relationships.
+ */
+export const queryRelationshipTypesOp = defineOperation({
+	name: "query-relationship-types",
+	description: "Query valid endpoint types for all relationship types",
+	input: z.object({}),
+	output: QueryRelationshipTypesResult,
+	fn: (): RelationshipTypeInfo[] => {
+		return Object.entries(RELATIONSHIP_ENDPOINT_TYPES).map(
+			([relType, endpoints]) => ({
+				type: RelationshipType.parse(relType),
+				from: endpoints.from,
+				to: endpoints.to,
+			}),
+		);
+	},
+});