feat(workflow-protocol): add declarative moderator table types and tableToModerator

Add ModeratorCondition, FALLBACK, ModeratorTransition, ModeratorTable types
and tableToModerator converter function. Export from workflow-protocol and
re-export from workflow-runtime for backward compat.

Refs #172

packages/workflow-protocol/src/index.ts

@@ -17,9 +17,13 @@ export type {
   ExtractContext,
   ExtractFn,
   ExtractResult,
+  FALLBACK,
   LlmProvider,
   Moderator,
+  ModeratorCondition,
   ModeratorContext,
+  ModeratorTable,
+  ModeratorTransition,
   ProviderConfig,
   ResolvedModel,
   Result,
@@ -47,3 +51,7 @@ export { END, START } from "./types.js";
 // ── Constructor functions ──────────────────────────────────────────
 
 export { err, ok } from "./result.js";
+
+// ── Moderator Table ────────────────────────────────────────────────
+
+export { tableToModerator } from "./moderator-table.js";

packages/workflow-protocol/src/moderator-table.ts

@@ -0,0 +1,24 @@
+import type { Moderator, ModeratorTable, RoleMeta } from "./types.js";
+import { END, START } from "./types.js";
+
+export function tableToModerator<M extends RoleMeta>(
+	table: ModeratorTable<M>,
+): Moderator<M> {
+	return (ctx) => {
+		const lastStep = ctx.steps.length > 0 ? ctx.steps[ctx.steps.length - 1] : null;
+		const currentRole: string = lastStep ? lastStep.role : START;
+
+		const transitions = (table as Record<string, (typeof table)[string]>)[currentRole];
+		if (!transitions) {
+			return END;
+		}
+
+		for (const transition of transitions) {
+			if (transition.condition === "FALLBACK" || transition.condition.check(ctx)) {
+				return transition.role;
+			}
+		}
+
+		return END;
+	};
+}

packages/workflow-protocol/src/types.ts

@@ -169,6 +169,28 @@ export type WorkflowDefinition<M extends RoleMeta> = {
   moderator: Moderator<M>;
 };
 
+// ── Declarative Moderator Table ────────────────────────────────────
+
+export type ModeratorCondition<M extends RoleMeta> = {
+	name: string;
+	description: string;
+	check: (ctx: ModeratorContext<M>) => boolean;
+};
+
+export type FALLBACK = "FALLBACK";
+
+export type ModeratorTransition<M extends RoleMeta> = {
+	condition: ModeratorCondition<M> | FALLBACK;
+	role: (keyof M & string) | typeof END;
+};
+
+export type ModeratorTable<M extends RoleMeta> = Record<
+	(keyof M & string) | typeof START,
+	ModeratorTransition<M>[]
+>;
+
+// ── Advance Outcome ────────────────────────────────────────────────
+
 export type AdvanceOutcome<M extends RoleMeta> =
   | { kind: "complete"; completion: WorkflowCompletion }
   | { kind: "yield"; output: RoleOutput; step: RoleStep<M> };