diff --git a/bunfig.toml b/bunfig.toml
new file mode 100644
index 0000000..e77c92c
--- /dev/null
+++ b/bunfig.toml
@@ -0,0 +1,2 @@
+[test]
+pathIgnorePatterns = ["dist/**"]
diff --git a/examples/hello-world.ts b/examples/hello-world.ts
index 777dadb..b79ec03 100644
--- a/examples/hello-world.ts
+++ b/examples/hello-world.ts
@@ -1,9 +1,14 @@
-import { createRoleModerator, END, type Role } from "@uncaged/workflow";
+import { createRoleModerator, END, type RoleDefinition } from "@uncaged/workflow";
+import * as z from "zod/v4";
 
 type Roles = {
   greeter: { greeting: string };
 };
 
+const greeterMetaSchema = z.object({
+  greeting: z.string(),
+});
+
 export const descriptor = {
   description: "A simple hello world workflow",
   roles: {
@@ -18,10 +23,14 @@ export const descriptor = {
   },
 };
 
-const greeter: Role<Roles["greeter"]> = async (ctx) => ({
-  content: `Hello, ${ctx.start.content}`,
-  meta: { greeting: "Hello!" },
-});
+const greeter: RoleDefinition<Roles["greeter"]> = {
+  description: "Generates a greeting",
+  schema: greeterMetaSchema,
+  run: async (ctx) => ({
+    content: `Hello, ${ctx.start.content}`,
+    meta: { greeting: "Hello!" },
+  }),
+};
 
 export const run = createRoleModerator<Roles>({
   roles: { greeter },
diff --git a/examples/package.json b/examples/package.json
index 7cca085..f9b7e90 100644
--- a/examples/package.json
+++ b/examples/package.json
@@ -3,6 +3,7 @@
   "private": true,
   "type": "module",
   "dependencies": {
-    "@uncaged/workflow": "workspace:*"
+    "@uncaged/workflow": "workspace:*",
+    "zod": "^4.0.0"
   }
 }
diff --git a/packages/workflow-agent-llm/__tests__/create-llm-adapter.test.ts b/packages/workflow-agent-llm/__tests__/create-llm-adapter.test.ts
index 13f1655..34ead8d 100644
--- a/packages/workflow-agent-llm/__tests__/create-llm-adapter.test.ts
+++ b/packages/workflow-agent-llm/__tests__/create-llm-adapter.test.ts
@@ -11,8 +11,8 @@ function makeCtx(userContent: string): ThreadContext {
       meta: { maxRounds: 10 },
       timestamp: 1,
     },
-      steps: [],
-      threadId: "01TEST000000000000000000TR",
+    steps: [],
+    threadId: "01TEST000000000000000000TR",
   };
 }
 
diff --git a/packages/workflow-agent-llm/src/index.ts b/packages/workflow-agent-llm/src/index.ts
index 55be074..bff293a 100644
--- a/packages/workflow-agent-llm/src/index.ts
+++ b/packages/workflow-agent-llm/src/index.ts
@@ -1,5 +1,4 @@
 export {
-  buildDescriptorFromRoles,
   type CreateRoleArgs,
   createRole,
   decorateRole,
@@ -15,7 +14,6 @@ export {
   type OnFailOptions,
   onFail,
   type RoleDecorator,
-  type RoleDescriptorInput,
   type WithDryRunOptions,
   withDryRun,
 } from "@uncaged/workflow-util-role";
diff --git a/packages/workflow-role-committer/__tests__/committer.test.ts b/packages/workflow-role-committer/__tests__/committer.test.ts
index d62f7fd..3eeb54c 100644
--- a/packages/workflow-role-committer/__tests__/committer.test.ts
+++ b/packages/workflow-role-committer/__tests__/committer.test.ts
@@ -8,7 +8,7 @@ import { createCommitterRole } from "../src/committer.js";
 
 function makeCtx(): ThreadContext {
   return {
-    threadId: "01TEST00000000000000000000",
+    threadId: "01TEST000000000000000000TR",
     start: {
       role: START,
       content: "do thing",
diff --git a/packages/workflow-role-reviewer/__tests__/reviewer.test.ts b/packages/workflow-role-reviewer/__tests__/reviewer.test.ts
index 5e79a0d..ff7ae48 100644
--- a/packages/workflow-role-reviewer/__tests__/reviewer.test.ts
+++ b/packages/workflow-role-reviewer/__tests__/reviewer.test.ts
@@ -29,7 +29,7 @@ function toolCallResponse(argsJson: string): Response {
 
 function makeCtx(): ThreadContext {
   return {
-    threadId: "01TEST00000000000000000000",
+    threadId: "01TEST000000000000000000TR",
     start: {
       role: START,
       content: "task",
@@ -106,6 +106,6 @@ describe("createReviewerRole", () => {
       { cwd: "/proj" },
     );
     await role(makeCtx());
-    expect(seen).toContain("uncaged-workflow thread 01TEST00000000000000000000");
+    expect(seen).toContain("uncaged-workflow thread 01TEST000000000000000000TR");
   });
 });
diff --git a/packages/workflow-template-solve-issue/__tests__/solve-issue-template.test.ts b/packages/workflow-template-solve-issue/__tests__/solve-issue-template.test.ts
index c215032..2a8efdb 100644
--- a/packages/workflow-template-solve-issue/__tests__/solve-issue-template.test.ts
+++ b/packages/workflow-template-solve-issue/__tests__/solve-issue-template.test.ts
@@ -25,7 +25,7 @@ function makeCtx(
   steps: ThreadContext<SolveIssueMeta>["steps"],
 ): ThreadContext<SolveIssueMeta> {
   return {
-    threadId: "01TEST00000000000000000000",
+    threadId: "01TEST000000000000000000TR",
     start: makeStart(maxRounds),
     steps,
   };
@@ -112,13 +112,13 @@ describe("createSolveIssueRoles", () => {
       extract: null,
     });
 
-    expect(typeof roles.planner).toBe("function");
-    expect(typeof roles.coder).toBe("function");
-    expect(typeof roles.reviewer).toBe("function");
-    expect(typeof roles.committer).toBe("function");
+    expect(typeof roles.planner.run).toBe("function");
+    expect(typeof roles.coder.run).toBe("function");
+    expect(typeof roles.reviewer.run).toBe("function");
+    expect(typeof roles.committer.run).toBe("function");
 
     const ctx = makeCtx(10, []);
-    const plannerOut = await roles.planner(ctx as unknown as ThreadContext);
+    const plannerOut = await roles.planner.run(ctx as unknown as ThreadContext);
     expect(plannerOut.meta.plan).toBe("");
     expect(Array.isArray(plannerOut.meta.files)).toBe(true);
   });
diff --git a/packages/workflow-template-solve-issue/src/descriptor.ts b/packages/workflow-template-solve-issue/src/descriptor.ts
index ab6ffcc..2306fc4 100644
--- a/packages/workflow-template-solve-issue/src/descriptor.ts
+++ b/packages/workflow-template-solve-issue/src/descriptor.ts
@@ -1,34 +1,22 @@
-import { committerMetaSchema } from "@uncaged/workflow-role-committer";
-import { reviewerMetaSchema } from "@uncaged/workflow-role-reviewer";
-import { buildDescriptorFromRoles } from "@uncaged/workflow-util-role";
+import { buildDescriptor } from "@uncaged/workflow";
 
-import { coderMetaSchema, plannerMetaSchema } from "./roles.js";
+import { solveIssueModerator } from "./moderator.js";
+import {
+  createSolveIssueRoles,
+  SOLVE_ISSUE_WORKFLOW_DESCRIPTION,
+  type SolveIssueRolesConfig,
+} from "./roles.js";
+
+const BUILD_DESCRIPTOR_CONFIG: SolveIssueRolesConfig = {
+  agent: async () => "",
+  workdir: "/tmp/uncaged-workflow-descriptor-stub",
+  extract: null,
+};
 
 export function buildSolveIssueDescriptor() {
-  return buildDescriptorFromRoles({
-    description:
-      "Plan, implement, review, and commit changes to resolve an issue end-to-end (planner → coder → reviewer → committer).",
-    roles: {
-      planner: {
-        name: "planner",
-        schema: plannerMetaSchema,
-        description: "Analyzes the issue and proposes plan, files, and approach.",
-      },
-      coder: {
-        name: "coder",
-        schema: coderMetaSchema,
-        description: "Implements the planner output and summarizes touched files.",
-      },
-      reviewer: {
-        name: "reviewer",
-        schema: reviewerMetaSchema,
-        description: "Runs git diff checks and sets approved when the change is ready.",
-      },
-      committer: {
-        name: "committer",
-        schema: committerMetaSchema,
-        description: "Creates branch, commits, and pushes when review passes.",
-      },
-    },
+  return buildDescriptor({
+    description: SOLVE_ISSUE_WORKFLOW_DESCRIPTION,
+    roles: createSolveIssueRoles(BUILD_DESCRIPTOR_CONFIG),
+    moderator: solveIssueModerator,
   });
 }
diff --git a/packages/workflow-template-solve-issue/src/index.ts b/packages/workflow-template-solve-issue/src/index.ts
index 61b0894..e64a205 100644
--- a/packages/workflow-template-solve-issue/src/index.ts
+++ b/packages/workflow-template-solve-issue/src/index.ts
@@ -1,7 +1,12 @@
-import { createRoleModerator, type WorkflowFn } from "@uncaged/workflow";
+import { createRoleModerator, type WorkflowDefinition, type WorkflowFn } from "@uncaged/workflow";
 
 import { solveIssueModerator } from "./moderator.js";
-import { createSolveIssueRoles, type SolveIssueMeta, type SolveIssueRolesConfig } from "./roles.js";
+import {
+  createSolveIssueRoles,
+  SOLVE_ISSUE_WORKFLOW_DESCRIPTION,
+  type SolveIssueMeta,
+  type SolveIssueRolesConfig,
+} from "./roles.js";
 
 export { type CursorAgentConfig, createCursorAgent } from "@uncaged/workflow-agent-cursor";
 export { buildSolveIssueDescriptor } from "./descriptor.js";
@@ -12,18 +17,26 @@ export {
   createSolveIssueRoles,
   type PlannerMeta,
   plannerMetaSchema,
+  SOLVE_ISSUE_WORKFLOW_DESCRIPTION,
   type SolveIssueMeta,
   type SolveIssueRoles,
   type SolveIssueRolesConfig,
 } from "./roles.js";
 
+export function createSolveIssueWorkflowDefinition(
+  config: SolveIssueRolesConfig,
+): WorkflowDefinition<SolveIssueMeta> {
+  return {
+    description: SOLVE_ISSUE_WORKFLOW_DESCRIPTION,
+    roles: createSolveIssueRoles(config),
+    moderator: solveIssueModerator,
+  };
+}
+
 /**
  * Factory for a {@link WorkflowFn}: supply an agent and repo paths at runtime, then pass the result
  * to the bundle `run` export pattern (`createRoleModerator` is already applied).
  */
 export function createSolveIssueRun(config: SolveIssueRolesConfig): WorkflowFn {
-  return createRoleModerator<SolveIssueMeta>({
-    roles: createSolveIssueRoles(config),
-    moderator: solveIssueModerator,
-  });
+  return createRoleModerator(createSolveIssueWorkflowDefinition(config));
 }
diff --git a/packages/workflow-template-solve-issue/src/roles.ts b/packages/workflow-template-solve-issue/src/roles.ts
index b97c2f4..3a7e0a6 100644
--- a/packages/workflow-template-solve-issue/src/roles.ts
+++ b/packages/workflow-template-solve-issue/src/roles.ts
@@ -1,7 +1,15 @@
-import type { AgentFn, Role } from "@uncaged/workflow";
+import type { AgentFn, RoleDefinition } from "@uncaged/workflow";
 import { createRole } from "@uncaged/workflow-agent-llm";
-import { type CommitterMeta, createCommitterRole } from "@uncaged/workflow-role-committer";
-import { createReviewerRole, type ReviewerMeta } from "@uncaged/workflow-role-reviewer";
+import {
+  type CommitterMeta,
+  committerMetaSchema,
+  createCommitterRole,
+} from "@uncaged/workflow-role-committer";
+import {
+  createReviewerRole,
+  type ReviewerMeta,
+  reviewerMetaSchema,
+} from "@uncaged/workflow-role-reviewer";
 import type { LlmProvider } from "@uncaged/workflow-util-role";
 import * as z from "zod/v4";
 
@@ -19,6 +27,9 @@ const CODER_SYSTEM = `You are a **coder**. The previous step produced a plan: re
 
 Make focused changes, follow project conventions, and explain what you changed.`;
 
+export const SOLVE_ISSUE_WORKFLOW_DESCRIPTION =
+  "Plan, implement, review, and commit changes to resolve an issue end-to-end (planner → coder → reviewer → committer).";
+
 export const plannerMetaSchema = z.object({
   plan: z.string(),
   files: z.array(z.string()),
@@ -80,10 +91,10 @@ function resolveExtract(config: SolveIssueRolesConfig): {
 }
 
 export type SolveIssueRoles = {
-  planner: Role<PlannerMeta>;
-  coder: Role<CoderMeta>;
-  reviewer: Role<ReviewerMeta>;
-  committer: Role<CommitterMeta>;
+  planner: RoleDefinition<PlannerMeta>;
+  coder: RoleDefinition<CoderMeta>;
+  reviewer: RoleDefinition<ReviewerMeta>;
+  committer: RoleDefinition<CommitterMeta>;
 };
 
 export function createSolveIssueRoles(config: SolveIssueRolesConfig): SolveIssueRoles {
@@ -95,7 +106,7 @@ export function createSolveIssueRoles(config: SolveIssueRolesConfig): SolveIssue
     cwd: config.workdir,
   };
 
-  const planner: Role<PlannerMeta> = createRole({
+  const plannerRun = createRole({
     name: "planner",
     schema: plannerMetaSchema,
     systemPrompt: PLANNER_SYSTEM,
@@ -107,7 +118,7 @@ export function createSolveIssueRoles(config: SolveIssueRolesConfig): SolveIssue
     },
   });
 
-  const coder: Role<CoderMeta> = createRole({
+  const coderRun = createRole({
     name: "coder",
     schema: coderMetaSchema,
     systemPrompt: CODER_SYSTEM,
@@ -119,7 +130,7 @@ export function createSolveIssueRoles(config: SolveIssueRolesConfig): SolveIssue
     },
   });
 
-  const reviewer: Role<ReviewerMeta> = createReviewerRole(
+  const reviewerRun = createReviewerRole(
     config.agent,
     {
       provider: extract.provider,
@@ -129,7 +140,7 @@ export function createSolveIssueRoles(config: SolveIssueRolesConfig): SolveIssue
     reviewerConfig,
   );
 
-  const committer: Role<CommitterMeta> = createCommitterRole(
+  const committerRun = createCommitterRole(
     config.agent,
     {
       provider: extract.provider,
@@ -139,5 +150,26 @@ export function createSolveIssueRoles(config: SolveIssueRolesConfig): SolveIssue
     committerConfig,
   );
 
-  return { planner, coder, reviewer, committer };
+  return {
+    planner: {
+      description: "Analyzes the issue and proposes plan, files, and approach.",
+      run: plannerRun,
+      schema: plannerMetaSchema,
+    },
+    coder: {
+      description: "Implements the planner output and summarizes touched files.",
+      run: coderRun,
+      schema: coderMetaSchema,
+    },
+    reviewer: {
+      description: "Runs git diff checks and sets approved when the change is ready.",
+      run: reviewerRun,
+      schema: reviewerMetaSchema,
+    },
+    committer: {
+      description: "Creates branch, commits, and pushes when review passes.",
+      run: committerRun,
+      schema: committerMetaSchema,
+    },
+  };
 }
diff --git a/packages/workflow-util-role/__tests__/build-descriptor.test.ts b/packages/workflow-util-role/__tests__/build-descriptor.test.ts
deleted file mode 100644
index b0ef374..0000000
--- a/packages/workflow-util-role/__tests__/build-descriptor.test.ts
+++ /dev/null
@@ -1,74 +0,0 @@
-import { describe, expect, test } from "bun:test";
-import { validateWorkflowDescriptor } from "@uncaged/workflow";
-import * as z from "zod/v4";
-
-import { buildDescriptorFromRoles } from "../src/build-descriptor.js";
-
-describe("buildDescriptorFromRoles", () => {
-  test("produces a descriptor that validates and includes JSON schemas per role", () => {
-    const schema = z.object({
-      title: z.string(),
-      count: z.number(),
-    });
-
-    const descriptor = buildDescriptorFromRoles({
-      description: "Demo workflow",
-      roles: {
-        analyst: {
-          name: "analyst",
-          schema,
-          description: "Analyzes input",
-        },
-      },
-    });
-
-    const validated = validateWorkflowDescriptor(descriptor);
-    expect(validated.ok).toBe(true);
-    if (!validated.ok) {
-      return;
-    }
-
-    expect(validated.value.description).toBe("Demo workflow");
-    const analyst = validated.value.roles.analyst;
-    expect(analyst.description).toBe("Analyzes input");
-    expect(analyst.schema.type).toBe("object");
-    const props = analyst.schema.properties as Record<string, unknown>;
-    expect(props.title).toMatchObject({ type: "string" });
-    expect(props.count).toMatchObject({ type: "number" });
-  });
-
-  test("uses empty description when spec.description is null", () => {
-    const descriptor = buildDescriptorFromRoles({
-      description: "W",
-      roles: {
-        x: {
-          name: "x",
-          schema: z.object({ n: z.number() }),
-          description: null,
-        },
-      },
-    });
-
-    const validated = validateWorkflowDescriptor(descriptor);
-    expect(validated.ok).toBe(true);
-    if (!validated.ok) {
-      return;
-    }
-    expect(validated.value.roles.x.description).toBe("");
-  });
-
-  test("throws when role key and spec.name diverge", () => {
-    expect(() =>
-      buildDescriptorFromRoles({
-        description: "W",
-        roles: {
-          a: {
-            name: "b",
-            schema: z.object({ n: z.number() }),
-            description: null,
-          },
-        },
-      }),
-    ).toThrow(/must match spec.name/);
-  });
-});
diff --git a/packages/workflow-util-role/__tests__/create-role.test.ts b/packages/workflow-util-role/__tests__/create-role.test.ts
index 91b3c22..5505e5c 100644
--- a/packages/workflow-util-role/__tests__/create-role.test.ts
+++ b/packages/workflow-util-role/__tests__/create-role.test.ts
@@ -42,8 +42,8 @@ function makeCtx(): ThreadContext {
       meta: { maxRounds: 10 },
       timestamp: Date.now(),
     },
-      steps: [],
-      threadId: "01TEST000000000000000000TR",
+    steps: [],
+    threadId: "01TEST000000000000000000TR",
   };
 }
 
diff --git a/packages/workflow-util-role/__tests__/decorators.test.ts b/packages/workflow-util-role/__tests__/decorators.test.ts
index 44d600d..270c962 100644
--- a/packages/workflow-util-role/__tests__/decorators.test.ts
+++ b/packages/workflow-util-role/__tests__/decorators.test.ts
@@ -16,8 +16,8 @@ function fakeCtx(): ThreadContext {
       },
       timestamp: Date.now(),
     },
-      steps: [],
-      threadId: "01TEST000000000000000000TR",
+    steps: [],
+    threadId: "01TEST000000000000000000TR",
   };
 }
 
diff --git a/packages/workflow-util-role/src/build-descriptor.ts b/packages/workflow-util-role/src/build-descriptor.ts
deleted file mode 100644
index 8fbd4c2..0000000
--- a/packages/workflow-util-role/src/build-descriptor.ts
+++ /dev/null
@@ -1,38 +0,0 @@
-import type { WorkflowDescriptor, WorkflowRoleSchema } from "@uncaged/workflow";
-import * as z from "zod/v4";
-
-export type RoleDescriptorInput<M extends Record<string, unknown> = Record<string, unknown>> = {
-  name: string;
-  schema: z.ZodType<M>;
-  /** Human-readable role description; use empty string when unknown. */
-  description: string | null;
-};
-
-function stripJsonSchemaMeta(json: Record<string, unknown>): WorkflowRoleSchema {
-  const { $schema: _drop, ...rest } = json;
-  return rest as WorkflowRoleSchema;
-}
-
-/**
- * Builds a {@link WorkflowDescriptor} from role specs, emitting JSON Schema per role via
- * `z.toJSONSchema`.
- */
-export function buildDescriptorFromRoles(args: {
-  description: string;
-  roles: Record<string, RoleDescriptorInput>;
-}): WorkflowDescriptor {
-  const roles: WorkflowDescriptor["roles"] = {};
-  for (const [key, spec] of Object.entries(args.roles)) {
-    if (spec.name !== key) {
-      throw new Error(
-        `buildDescriptorFromRoles: role key "${key}" must match spec.name "${spec.name}"`,
-      );
-    }
-    const rawJsonSchema = z.toJSONSchema(spec.schema) as Record<string, unknown>;
-    roles[key] = {
-      description: spec.description === null ? "" : spec.description,
-      schema: stripJsonSchemaMeta(rawJsonSchema),
-    };
-  }
-  return { description: args.description, roles };
-}
diff --git a/packages/workflow-util-role/src/index.ts b/packages/workflow-util-role/src/index.ts
index 9a652e1..c7b735a 100644
--- a/packages/workflow-util-role/src/index.ts
+++ b/packages/workflow-util-role/src/index.ts
@@ -1,4 +1,3 @@
-export { buildDescriptorFromRoles, type RoleDescriptorInput } from "./build-descriptor.js";
 export { type CreateRoleArgs, createRole } from "./create-role.js";
 export {
   decorateRole,
diff --git a/packages/workflow/__tests__/build-descriptor.test.ts b/packages/workflow/__tests__/build-descriptor.test.ts
new file mode 100644
index 0000000..3ff2619
--- /dev/null
+++ b/packages/workflow/__tests__/build-descriptor.test.ts
@@ -0,0 +1,43 @@
+import { describe, expect, test } from "bun:test";
+import * as z from "zod/v4";
+
+import { buildDescriptor } from "../src/build-descriptor.js";
+import { END } from "../src/types.js";
+import { validateWorkflowDescriptor } from "../src/workflow-descriptor.js";
+
+describe("buildDescriptor", () => {
+  test("produces a descriptor that validates and includes JSON schemas per role", () => {
+    const schema = z.object({
+      title: z.string(),
+      count: z.number(),
+    });
+
+    type M = { analyst: z.infer<typeof schema> };
+
+    const descriptor = buildDescriptor<M>({
+      description: "Demo workflow",
+      roles: {
+        analyst: {
+          description: "Analyzes input",
+          schema,
+          run: async () => ({ content: "", meta: { title: "", count: 0 } }),
+        },
+      },
+      moderator: () => END,
+    });
+
+    const validated = validateWorkflowDescriptor(descriptor);
+    expect(validated.ok).toBe(true);
+    if (!validated.ok) {
+      return;
+    }
+
+    expect(validated.value.description).toBe("Demo workflow");
+    const analyst = validated.value.roles.analyst;
+    expect(analyst.description).toBe("Analyzes input");
+    expect(analyst.schema.type).toBe("object");
+    const props = analyst.schema.properties as Record<string, unknown>;
+    expect(props.title).toMatchObject({ type: "string" });
+    expect(props.count).toMatchObject({ type: "number" });
+  });
+});
diff --git a/packages/workflow/__tests__/engine.test.ts b/packages/workflow/__tests__/engine.test.ts
index f08cb96..c0fe96c 100644
--- a/packages/workflow/__tests__/engine.test.ts
+++ b/packages/workflow/__tests__/engine.test.ts
@@ -2,27 +2,45 @@ import { describe, expect, test } from "bun:test";
 import { mkdir, mkdtemp, readFile, rm } from "node:fs/promises";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
+import * as z from "zod/v4";
 
 import { createRoleModerator } from "../src/create-role-moderator.js";
 import { executeThread } from "../src/engine.js";
 import { createLogger } from "../src/logger.js";
 import { END } from "../src/types.js";
 
+const plannerMetaSchema = z.object({
+  plan: z.string(),
+  files: z.array(z.string()),
+});
+
+const coderMetaSchema = z.object({
+  diff: z.string(),
+});
+
 type DemoMeta = {
-  planner: Record<string, unknown>;
-  coder: Record<string, unknown>;
+  planner: z.infer<typeof plannerMetaSchema>;
+  coder: z.infer<typeof coderMetaSchema>;
 };
 
 const demoWorkflow = createRoleModerator<DemoMeta>({
   roles: {
-    planner: async () => ({
-      content: "plan-body",
-      meta: { plan: "do-it", files: ["a.ts"] },
-    }),
-    coder: async () => ({
-      content: "code-body",
-      meta: { diff: "+ok" },
-    }),
+    planner: {
+      description: "Demo planner",
+      schema: plannerMetaSchema,
+      run: async () => ({
+        content: "plan-body",
+        meta: { plan: "do-it", files: ["a.ts"] },
+      }),
+    },
+    coder: {
+      description: "Demo coder",
+      schema: coderMetaSchema,
+      run: async () => ({
+        content: "code-body",
+        meta: { diff: "+ok" },
+      }),
+    },
   },
   moderator: (ctx) => {
     if (ctx.steps.length === 0) {
diff --git a/packages/workflow/package.json b/packages/workflow/package.json
index f82b3c5..33b62d9 100644
--- a/packages/workflow/package.json
+++ b/packages/workflow/package.json
@@ -13,7 +13,11 @@
     "xxhashjs": "^0.2.2",
     "yaml": "^2.8.4"
   },
+  "peerDependencies": {
+    "zod": "^4.0.0"
+  },
   "devDependencies": {
-    "@types/acorn": "^6.0.4"
+    "@types/acorn": "^6.0.4",
+    "zod": "^4.0.0"
   }
 }
diff --git a/packages/workflow/src/build-descriptor.ts b/packages/workflow/src/build-descriptor.ts
new file mode 100644
index 0000000..a5171a5
--- /dev/null
+++ b/packages/workflow/src/build-descriptor.ts
@@ -0,0 +1,25 @@
+import * as z from "zod/v4";
+
+import type { RoleMeta, WorkflowDefinition } from "./types.js";
+import type { WorkflowDescriptor, WorkflowRoleSchema } from "./workflow-descriptor.js";
+
+function stripJsonSchemaMeta(json: Record<string, unknown>): WorkflowRoleSchema {
+  const { $schema: _drop, ...rest } = json;
+  return rest as WorkflowRoleSchema;
+}
+
+export function buildDescriptor<M extends RoleMeta>(
+  def: WorkflowDefinition<M>,
+): WorkflowDescriptor {
+  const roles: WorkflowDescriptor["roles"] = {};
+  for (const [key, roleDef] of Object.entries(def.roles) as Array<
+    [string, { description: string; schema: z.ZodType }]
+  >) {
+    const rawJsonSchema = z.toJSONSchema(roleDef.schema) as Record<string, unknown>;
+    roles[key] = {
+      description: roleDef.description,
+      schema: stripJsonSchemaMeta(rawJsonSchema),
+    };
+  }
+  return { description: def.description, roles };
+}
diff --git a/packages/workflow/src/create-role-moderator.ts b/packages/workflow/src/create-role-moderator.ts
index a5ed1af..5d24bf5 100644
--- a/packages/workflow/src/create-role-moderator.ts
+++ b/packages/workflow/src/create-role-moderator.ts
@@ -65,12 +65,12 @@ export function createRoleModerator<M extends RoleMeta>(
         return { returnCode: 0, summary: "completed: moderator returned END" };
       }
 
-      const roleFn = def.roles[next];
-      if (roleFn === undefined) {
+      const roleDef = def.roles[next];
+      if (roleDef === undefined) {
         return { returnCode: 1, summary: `unknown role: ${next}` };
       }
 
-      const result = await roleFn(ctx as unknown as ThreadContext);
+      const result = await roleDef.run(ctx as unknown as ThreadContext);
       const ts = Date.now();
       const step = {
         role: next,
diff --git a/packages/workflow/src/index.ts b/packages/workflow/src/index.ts
index 894f2be..c0638d6 100644
--- a/packages/workflow/src/index.ts
+++ b/packages/workflow/src/index.ts
@@ -5,6 +5,7 @@ export {
   encodeCrockfordBase32Bits,
   encodeUint64AsCrockford,
 } from "./base32.js";
+export { buildDescriptor } from "./build-descriptor.js";
 export { validateWorkflowBundle, type WorkflowBundleValidationInput } from "./bundle-validator.js";
 export { createRoleModerator } from "./create-role-moderator.js";
 export {
@@ -53,6 +54,7 @@ export {
   END,
   type Moderator,
   type Role,
+  type RoleDefinition,
   type RoleMeta,
   type RoleOutput,
   type RoleResult,
diff --git a/packages/workflow/src/types.ts b/packages/workflow/src/types.ts
index 517b272..a43aa5b 100644
--- a/packages/workflow/src/types.ts
+++ b/packages/workflow/src/types.ts
@@ -1,3 +1,5 @@
+import type * as z from "zod/v4";
+
 /** Sentinel values for automaton control flow. */
 export const START = "__start__" as const;
 export const END = "__end__" as const;
@@ -71,6 +73,13 @@ export type Role<Meta extends Record<string, unknown>> = (
   ctx: ThreadContext,
 ) => Promise<RoleResult<Meta>>;
 
+/** Role wiring: runtime {@link Role}, JSON Schema for `meta`, and human-readable description. */
+export type RoleDefinition<Meta extends Record<string, unknown>> = {
+  description: string;
+  run: Role<Meta>;
+  schema: z.ZodType<Meta>;
+};
+
 /**
  * An Agent — raw string output interface for LLM/CLI adapters.
  * Structured meta is extracted by the role's extract layer.
@@ -89,6 +98,7 @@ export type Moderator<M extends RoleMeta> = (
 
 /** Complete workflow definition as authored by users. */
 export type WorkflowDefinition<M extends RoleMeta> = {
-  roles: { [K in keyof M & string]: Role<M[K]> };
+  description: string;
+  roles: { [K in keyof M & string]: RoleDefinition<M[K]> };
   moderator: Moderator<M>;
 };