feat: add @uncaged/uwf-moderator with JSONata evaluation engine

5 tests passing:  transition, condition match, fallback,
missing role error, output expansion.

Refs #309, #311

packages/uwf-moderator/__tests__/evaluate.test.ts

@@ -0,0 +1,120 @@
+import { describe, expect, test } from "bun:test";
+import type { ModeratorContext, WorkflowPayload } from "@uncaged/uwf-protocol";
+
+import { evaluate } from "../src/evaluate.js";
+
+const solveIssueWorkflow: WorkflowPayload = {
+  name: "solve-issue",
+  description: "End-to-end issue resolution",
+  roles: {
+    planner: {
+      description: "Creates implementation plan",
+      systemPrompt: "You are a planning agent...",
+      outputSchema: "5GWKR8TN1V3JA",
+    },
+    developer: {
+      description: "Implements code changes",
+      systemPrompt: "You are a developer agent...",
+      outputSchema: "8CNWT4KR6D1HV",
+    },
+    reviewer: {
+      description: "Reviews code changes",
+      systemPrompt: "You are a code reviewer...",
+      outputSchema: "1VPBG9SM5E7WK",
+    },
+  },
+  conditions: {
+    needsClarification: {
+      description: "Planner requests clarification from user",
+      expression: "$exists(steps[-1].output.needsClarification)",
+    },
+    notApproved: {
+      description: "Reviewer rejected the implementation",
+      expression: "steps[-1].output.approved = false",
+    },
+  },
+  graph: {
+    $START: [{ role: "planner", condition: null }],
+    planner: [
+      { role: "developer", condition: "needsClarification" },
+      { role: "$END", condition: null },
+    ],
+    developer: [{ role: "reviewer", condition: null }],
+    reviewer: [
+      { role: "developer", condition: "notApproved" },
+      { role: "$END", condition: null },
+    ],
+  },
+};
+
+function makeContext(steps: ModeratorContext["steps"]): ModeratorContext {
+  return {
+    start: {
+      workflow: "4KNM2PXR3B1QW",
+      prompt: "Fix the login bug",
+    },
+    steps,
+  };
+}
+
+describe("evaluate", () => {
+  test("$START → first role (fallback)", () => {
+    const result = evaluate(solveIssueWorkflow, makeContext([]));
+    expect(result).toEqual({ ok: true, value: "planner" });
+  });
+
+  test("condition match (notApproved → developer)", () => {
+    const context = makeContext([
+      {
+        role: "reviewer",
+        output: { approved: false },
+        detail: "2MXBG6PN4A8JR",
+        agent: "uwf-hermes",
+      },
+    ]);
+    const result = evaluate(solveIssueWorkflow, context);
+    expect(result).toEqual({ ok: true, value: "developer" });
+  });
+
+  test("fallback when condition does not match → $END", () => {
+    const context = makeContext([
+      {
+        role: "reviewer",
+        output: { approved: true },
+        detail: "2MXBG6PN4A8JR",
+        agent: "uwf-hermes",
+      },
+    ]);
+    const result = evaluate(solveIssueWorkflow, context);
+    expect(result).toEqual({ ok: true, value: "$END" });
+  });
+
+  test("missing role in graph → error", () => {
+    const context = makeContext([
+      {
+        role: "unknown-role",
+        output: {},
+        detail: "2MXBG6PN4A8JR",
+        agent: "uwf-hermes",
+      },
+    ]);
+    const result = evaluate(solveIssueWorkflow, context);
+    expect(result.ok).toBe(false);
+    if (!result.ok) {
+      expect(result.error.message).toBe('no transitions defined for role "unknown-role"');
+    }
+  });
+
+  test("output expansion in context works with JSONata", () => {
+    const context = makeContext([
+      {
+        role: "planner",
+        output: { needsClarification: true },
+        detail: "7BQST3VW9F2MA",
+        agent: "uwf-hermes",
+      },
+    ]);
+    const result = evaluate(solveIssueWorkflow, context);
+    expect(result).toEqual({ ok: true, value: "developer" });
+  });
+});

packages/uwf-moderator/package.json

@@ -0,0 +1,30 @@
+{
+  "name": "@uncaged/uwf-moderator",
+  "version": "0.1.0",
+  "files": [
+    "src",
+    "dist",
+    "package.json"
+  ],
+  "type": "module",
+  "exports": {
+    ".": {
+      "bun": "./src/index.ts",
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js"
+    }
+  },
+  "scripts": {
+    "test": "bun test"
+  },
+  "dependencies": {
+    "@uncaged/uwf-protocol": "workspace:^",
+    "jsonata": "^1.8.7"
+  },
+  "devDependencies": {
+    "typescript": "^5.8.3"
+  },
+  "publishConfig": {
+    "access": "public"
+  }
+}

packages/uwf-moderator/src/evaluate.ts

@@ -0,0 +1,82 @@
+import type { ModeratorContext, WorkflowPayload } from "@uncaged/uwf-protocol";
+import jsonata from "jsonata";
+
+import type { Result } from "./types.js";
+
+const START_ROLE = "$START";
+
+function isTruthy(value: unknown): boolean {
+  if (value === null || value === undefined) {
+    return false;
+  }
+  if (typeof value === "boolean") {
+    return value;
+  }
+  if (typeof value === "number") {
+    return value !== 0 && !Number.isNaN(value);
+  }
+  if (typeof value === "string") {
+    return value.length > 0;
+  }
+  return true;
+}
+
+function evaluateJsonata(expression: string, context: ModeratorContext): Result<unknown, Error> {
+  try {
+    const result = jsonata(expression).evaluate(context);
+    return { ok: true, value: result };
+  } catch (error) {
+    return {
+      ok: false,
+      error: error instanceof Error ? error : new Error(String(error)),
+    };
+  }
+}
+
+function currentRole(context: ModeratorContext): string {
+  if (context.steps.length === 0) {
+    return START_ROLE;
+  }
+  return context.steps[context.steps.length - 1].role;
+}
+
+export function evaluate(
+  workflow: WorkflowPayload,
+  context: ModeratorContext,
+): Result<string, Error> {
+  const role = currentRole(context);
+  const transitions = workflow.graph[role];
+  if (transitions === undefined) {
+    return {
+      ok: false,
+      error: new Error(`no transitions defined for role "${role}"`),
+    };
+  }
+
+  for (const transition of transitions) {
+    if (transition.condition === null) {
+      return { ok: true, value: transition.role };
+    }
+
+    const conditionDef = workflow.conditions[transition.condition];
+    if (conditionDef === undefined) {
+      return {
+        ok: false,
+        error: new Error(`unknown condition "${transition.condition}"`),
+      };
+    }
+
+    const evalResult = evaluateJsonata(conditionDef.expression, context);
+    if (!evalResult.ok) {
+      return evalResult;
+    }
+    if (isTruthy(evalResult.value)) {
+      return { ok: true, value: transition.role };
+    }
+  }
+
+  return {
+    ok: false,
+    error: new Error(`no transition matched for role "${role}"`),
+  };
+}

packages/uwf-moderator/src/index.ts

@@ -0,0 +1 @@
+export { evaluate } from "./evaluate.js";

packages/uwf-moderator/src/types.ts

@@ -0,0 +1 @@
+export type Result<T, E> = { ok: true; value: T } | { ok: false; error: E };

packages/uwf-moderator/tsconfig.json

@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "dist"
+  },
+  "include": ["src"],
+  "references": [{ "path": "../uwf-protocol" }]
+}