diff --git a/packages/agent-mock/__tests__/fixtures/simple-scenario.yaml b/packages/agent-mock/__tests__/fixtures/simple-scenario.yaml
new file mode 100644
index 0000000..58c452a
--- /dev/null
+++ b/packages/agent-mock/__tests__/fixtures/simple-scenario.yaml
@@ -0,0 +1,18 @@
+steps:
+  - role: planner
+    output: |
+      ---
+      $status: ready
+      plan: test-plan-hash
+      repoPath: /tmp/test-repo
+      ---
+      Plan: implement the feature.
+
+  - role: developer
+    output: |
+      ---
+      $status: done
+      branch: fix/1-test
+      worktree: /tmp/worktree
+      ---
+      Implemented the feature.
diff --git a/packages/agent-mock/__tests__/mock-agent.test.ts b/packages/agent-mock/__tests__/mock-agent.test.ts
new file mode 100644
index 0000000..2cafb2e
--- /dev/null
+++ b/packages/agent-mock/__tests__/mock-agent.test.ts
@@ -0,0 +1,48 @@
+import { readFile } from "node:fs/promises";
+import { join } from "node:path";
+import { describe, expect, test } from "vitest";
+
+import { parseScenario, selectMockStep } from "../src/mock-agent.js";
+
+const FIXTURE = join(__dirname, "fixtures", "simple-scenario.yaml");
+
+describe("parseScenario", () => {
+  test("parses the 2-step fixture in order", async () => {
+    const scenario = parseScenario(await readFile(FIXTURE, "utf8"));
+    expect(scenario.steps).toHaveLength(2);
+    expect(scenario.steps[0].role).toBe("planner");
+    expect(scenario.steps[1].role).toBe("developer");
+    expect(scenario.steps[0].output).toContain("$status: ready");
+    expect(scenario.steps[1].output).toContain("branch: fix/1-test");
+  });
+
+  test("rejects documents without a steps array", () => {
+    expect(() => parseScenario("foo: bar")).toThrow(/steps/);
+  });
+
+  test("rejects steps missing role or output", () => {
+    expect(() => parseScenario("steps:\n  - role: planner")).toThrow(/role.*output/);
+  });
+});
+
+describe("selectMockStep", () => {
+  const scenario = {
+    steps: [
+      { role: "planner", output: "plan-output" },
+      { role: "developer", output: "dev-output" },
+    ],
+  };
+
+  test("step index counts existing steps to pick the current step", () => {
+    expect(selectMockStep(scenario, 0, "planner").output).toBe("plan-output");
+    expect(selectMockStep(scenario, 1, "developer").output).toBe("dev-output");
+  });
+
+  test("throws when the moderator routes to an unexpected role", () => {
+    expect(() => selectMockStep(scenario, 0, "developer")).toThrow(/expected role "planner"/);
+  });
+
+  test("throws when the step index runs past the scripted steps", () => {
+    expect(() => selectMockStep(scenario, 2, "planner")).toThrow(/no step at index 2/);
+  });
+});
diff --git a/packages/agent-mock/package.json b/packages/agent-mock/package.json
new file mode 100644
index 0000000..62fe149
--- /dev/null
+++ b/packages/agent-mock/package.json
@@ -0,0 +1,47 @@
+{
+  "name": "@united-workforce/agent-mock",
+  "version": "0.5.0",
+  "files": [
+    "src",
+    "dist",
+    "package.json"
+  ],
+  "type": "module",
+  "bin": {
+    "uwf-mock": "./src/cli.ts"
+  },
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js"
+    }
+  },
+  "scripts": {
+    "prepublishOnly": "echo 'Use pnpm run release from repo root' && exit 1",
+    "test": "vitest run __tests__/",
+    "test:ci": "vitest run __tests__/"
+  },
+  "dependencies": {
+    "@ocas/core": "^0.3.0",
+    "@united-workforce/protocol": "workspace:^",
+    "@united-workforce/util": "workspace:^",
+    "@united-workforce/util-agent": "workspace:^",
+    "yaml": "^2.9.0"
+  },
+  "devDependencies": {
+    "typescript": "^5.8.3"
+  },
+  "publishConfig": {
+    "access": "public"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://git.shazhou.work/shazhou/united-workforce.git",
+    "directory": "packages/agent-mock"
+  },
+  "homepage": "https://git.shazhou.work/shazhou/united-workforce#readme",
+  "bugs": {
+    "url": "https://git.shazhou.work/shazhou/united-workforce/issues"
+  },
+  "license": "MIT"
+}
diff --git a/packages/agent-mock/src/cli.ts b/packages/agent-mock/src/cli.ts
new file mode 100644
index 0000000..2676ac6
--- /dev/null
+++ b/packages/agent-mock/src/cli.ts
@@ -0,0 +1,18 @@
+#!/usr/bin/env node
+
+import { createMockAgent } from "./mock-agent.js";
+
+const USAGE = "usage: uwf-mock --mock-data <path> --thread <id> --role <role> --prompt <text>";
+
+function getMockDataPath(argv: string[]): string {
+  const idx = argv.indexOf("--mock-data");
+  if (idx === -1 || idx + 1 >= argv.length || argv[idx + 1] === "") {
+    process.stderr.write(`--mock-data is required. ${USAGE}\n`);
+    process.exit(1);
+  }
+  return argv[idx + 1];
+}
+
+const mockDataPath = getMockDataPath(process.argv);
+const main = createMockAgent(mockDataPath);
+void main();
diff --git a/packages/agent-mock/src/index.ts b/packages/agent-mock/src/index.ts
new file mode 100644
index 0000000..4d36d72
--- /dev/null
+++ b/packages/agent-mock/src/index.ts
@@ -0,0 +1,2 @@
+export { createMockAgent, parseScenario, selectMockStep } from "./mock-agent.js";
+export type { MockScenario, MockStep } from "./types.js";
diff --git a/packages/agent-mock/src/mock-agent.ts b/packages/agent-mock/src/mock-agent.ts
new file mode 100644
index 0000000..1044232
--- /dev/null
+++ b/packages/agent-mock/src/mock-agent.ts
@@ -0,0 +1,128 @@
+import { readFile } from "node:fs/promises";
+
+import { bootstrap, type JSONSchema, putSchema, type Store } from "@ocas/core";
+import { createLogger } from "@united-workforce/util";
+import { type AgentContext, type AgentRunResult, createAgent } from "@united-workforce/util-agent";
+import { parse } from "yaml";
+
+import type { MockScenario, MockStep } from "./types.js";
+
+const log = createLogger({ sink: { kind: "stderr" } });
+
+const MOCK_DETAIL_SCHEMA: JSONSchema = {
+  title: "mock-detail",
+  type: "object",
+  required: ["sessionId", "role", "stepIndex"],
+  properties: {
+    sessionId: { type: "string" },
+    role: { type: "string" },
+    stepIndex: { type: "integer" },
+  },
+  additionalProperties: false,
+};
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null && !Array.isArray(value);
+}
+
+/** Parse a YAML mock data document into a {@link MockScenario}. Pure — no I/O. */
+export function parseScenario(text: string): MockScenario {
+  const raw = parse(text) as unknown;
+  if (!isRecord(raw) || !Array.isArray(raw.steps)) {
+    throw new Error("mock data must be a mapping with a 'steps' array");
+  }
+  const steps: MockStep[] = raw.steps.map((entry, i) => {
+    if (!isRecord(entry) || typeof entry.role !== "string" || typeof entry.output !== "string") {
+      throw new Error(`mock step ${i} must have string 'role' and string 'output'`);
+    }
+    return { role: entry.role, output: entry.output };
+  });
+  return { steps };
+}
+
+async function loadScenario(path: string): Promise<MockScenario> {
+  const text = await readFile(path, "utf8");
+  return parseScenario(text);
+}
+
+/**
+ * Pick the scripted step for the given index and verify the moderator routed to
+ * the expected role. Throws on out-of-range index or role mismatch so routing
+ * bugs surface loudly during E2E runs.
+ */
+export function selectMockStep(scenario: MockScenario, stepIndex: number, role: string): MockStep {
+  const step = scenario.steps[stepIndex];
+  if (step === undefined) {
+    throw new Error(
+      `mock scenario has no step at index ${stepIndex} (total ${scenario.steps.length}); ` +
+        `moderator routed to role "${role}"`,
+    );
+  }
+  if (step.role !== role) {
+    throw new Error(
+      `mock step ${stepIndex} expected role "${step.role}" but moderator routed to "${role}"`,
+    );
+  }
+  return step;
+}
+
+/** Persist a minimal detail node so the step node has a valid CAS ref. */
+async function storeMockDetail(
+  store: Store,
+  sessionId: string,
+  role: string,
+  stepIndex: number,
+): Promise<string> {
+  await bootstrap(store);
+  const schemaHash = await putSchema(store, MOCK_DETAIL_SCHEMA);
+  return store.cas.put(schemaHash, { sessionId, role, stepIndex });
+}
+
+/**
+ * Agent CLI factory: a deterministic, LLM-free agent that replays pre-scripted
+ * outputs from a YAML mock data file. The step index is derived by counting the
+ * existing steps in the thread's CAS chain (exposed via `ctx.steps`).
+ */
+export function createMockAgent(mockDataPath: string): () => Promise<void> {
+  let lastResult: AgentRunResult | null = null;
+
+  async function run(ctx: AgentContext): Promise<AgentRunResult> {
+    const scenario = await loadScenario(mockDataPath);
+    const stepIndex = ctx.steps.length;
+    log(
+      "MK7X2QPV",
+      `mock step ${stepIndex} for role "${ctx.role}" (${scenario.steps.length} scripted)`,
+    );
+
+    const step = selectMockStep(scenario, stepIndex, ctx.role);
+    const sessionId = `mock-${stepIndex}`;
+    const detailHash = await storeMockDetail(ctx.store, sessionId, ctx.role, stepIndex);
+
+    const result: AgentRunResult = {
+      output: step.output,
+      detailHash,
+      sessionId,
+      assembledPrompt: "",
+    };
+    lastResult = result;
+    return result;
+  }
+
+  async function continueRun(
+    sessionId: string,
+    _message: string,
+    _store: Store,
+  ): Promise<AgentRunResult> {
+    if (lastResult === null) {
+      throw new Error("mock continue called before run");
+    }
+    log("MK3N8RTW", `mock continue for session ${sessionId}, replaying scripted output`);
+    return lastResult;
+  }
+
+  return createAgent({
+    name: "mock",
+    run,
+    continue: continueRun,
+  });
+}
diff --git a/packages/agent-mock/src/types.ts b/packages/agent-mock/src/types.ts
new file mode 100644
index 0000000..63e83cf
--- /dev/null
+++ b/packages/agent-mock/src/types.ts
@@ -0,0 +1,12 @@
+/** One pre-scripted step in a mock scenario. */
+export type MockStep = {
+  /** Role this step is expected to run as. Validated against the actual `--role` argument. */
+  role: string;
+  /** Frontmatter markdown output the mock agent emits for this step. */
+  output: string;
+};
+
+/** Deterministic, pre-scripted agent script loaded from a YAML mock data file. */
+export type MockScenario = {
+  steps: MockStep[];
+};
diff --git a/packages/agent-mock/tsconfig.json b/packages/agent-mock/tsconfig.json
new file mode 100644
index 0000000..7b7fa2a
--- /dev/null
+++ b/packages/agent-mock/tsconfig.json
@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "dist"
+  },
+  "include": ["src"],
+  "references": [{ "path": "../util-agent" }, { "path": "../util" }, { "path": "../protocol" }]
+}
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 0bbdfce..1aa12c6 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -93,6 +93,28 @@ importers:
         specifier: ^5.8.3
         version: 5.9.3
 
+  packages/agent-mock:
+    dependencies:
+      '@ocas/core':
+        specifier: ^0.3.0
+        version: 0.3.0
+      '@united-workforce/protocol':
+        specifier: workspace:^
+        version: link:../protocol
+      '@united-workforce/util':
+        specifier: workspace:^
+        version: link:../util
+      '@united-workforce/util-agent':
+        specifier: workspace:^
+        version: link:../util-agent
+      yaml:
+        specifier: ^2.9.0
+        version: 2.9.0
+    devDependencies:
+      typescript:
+        specifier: ^5.8.3
+        version: 5.9.3
+
   packages/cli:
     dependencies:
       '@ocas/core':
diff --git a/proman.yaml b/proman.yaml
index 551f753..a0cc8e5 100644
--- a/proman.yaml
+++ b/proman.yaml
@@ -23,6 +23,10 @@ packages:
     path: packages/agent-builtin
     type: cli
 
+  - name: "@united-workforce/agent-mock"
+    path: packages/agent-mock
+    type: cli
+
   - name: "@united-workforce/cli"
     path: packages/cli
     type: cli
diff --git a/tsconfig.json b/tsconfig.json
index 1547e16..76e1129 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -23,6 +23,7 @@
     { "path": "packages/util-agent" },
     { "path": "packages/agent-hermes" },
     { "path": "packages/agent-builtin" },
+    { "path": "packages/agent-mock" },
     { "path": "packages/agent-claude-code" },
     { "path": "packages/cli" }
   ]