refactor: extract @uncaged/workflow-util-agent + smart prompt

- New package: spawn-cli + build-agent-prompt shared utils
- Smart prompt: start + meta summaries for middle steps + last step full
- Cursor/Hermes adapters now import from util-agent (no duplicate code)
- 109 tests pass, biome clean

Closes #14
小橘 <xiaoju@shazhou.work>

packages/workflow-agent-cursor/__tests__/cursor-agent.test.ts

@@ -1,26 +1,5 @@
 import { describe, expect, test } from "bun:test";
-import { START, type ThreadContext } from "@uncaged/workflow";
-
-import { buildAgentPrompt, createCursorAgent, validateCursorAgentConfig } from "../src/index.js";
-
-function makeCtx(): ThreadContext {
-  return {
-    start: {
-      role: START,
-      content: "user task",
-      meta: { maxRounds: 5 },
-      timestamp: 1,
-    },
-    steps: [
-      {
-        role: "coder",
-        content: "first draft",
-        meta: {},
-        timestamp: 2,
-      },
-    ],
-  };
-}
+import { createCursorAgent, validateCursorAgentConfig } from "../src/index.js";
 
 describe("validateCursorAgentConfig", () => {
   test("accepts valid config", () => {
@@ -54,16 +33,6 @@ describe("validateCursorAgentConfig", () => {
   });
 });
 
-describe("buildAgentPrompt", () => {
-  test("includes system prompt, start, and steps", () => {
-    const text = buildAgentPrompt(makeCtx(), "Be helpful.");
-    expect(text).toContain("Be helpful.");
-    expect(text).toContain("user task");
-    expect(text).toContain("coder");
-    expect(text).toContain("first draft");
-  });
-});
-
 describe("createCursorAgent", () => {
   test("returns an AgentFn", () => {
     const agent = createCursorAgent({

packages/workflow-agent-cursor/package.json

@@ -9,6 +9,7 @@
     "test": "bun test"
   },
   "dependencies": {
-    "@uncaged/workflow": "workspace:*"
+    "@uncaged/workflow": "workspace:*",
+    "@uncaged/workflow-util-agent": "workspace:*"
   }
 }

packages/workflow-agent-cursor/src/build-agent-prompt.ts

@@ -1,17 +0,0 @@
-import type { ThreadContext } from "@uncaged/workflow";
-
-/** Combines the role system prompt with thread start content and prior role outputs. */
-export function buildAgentPrompt(ctx: ThreadContext, systemPrompt: string): string {
-  const blocks: string[] = [];
-  blocks.push("# System instructions");
-  blocks.push(systemPrompt);
-  blocks.push("");
-  blocks.push("# Thread");
-  blocks.push("## Start");
-  blocks.push(ctx.start.content);
-  for (const step of ctx.steps) {
-    blocks.push(`## Role: ${step.role}`);
-    blocks.push(step.content);
-  }
-  return blocks.join("\n");
-}

packages/workflow-agent-cursor/src/index.ts

@@ -1,11 +1,10 @@
 import type { AgentFn } from "@uncaged/workflow";
+import { buildAgentPrompt, type SpawnCliError, spawnCli } from "@uncaged/workflow-util-agent";
 
-import { buildAgentPrompt } from "./build-agent-prompt.js";
-import { type SpawnCliError, spawnCli } from "./spawn-cli.js";
 import type { CursorAgentConfig } from "./types.js";
 import { validateCursorAgentConfig } from "./validate-config.js";
 
-export { buildAgentPrompt } from "./build-agent-prompt.js";
+export { buildAgentPrompt } from "@uncaged/workflow-util-agent";
 export type { CursorAgentConfig } from "./types.js";
 export { validateCursorAgentConfig } from "./validate-config.js";
 
@@ -39,7 +38,7 @@ export function createCursorAgent(config: CursorAgentConfig): AgentFn {
   const timeoutMs = config.timeout;
 
   return async (ctx, systemPrompt) => {
-    const fullPrompt = buildAgentPrompt(ctx, systemPrompt);
+    const fullPrompt = buildAgentPrompt(systemPrompt, ctx);
     const args = [
       "-p",
       fullPrompt,

packages/workflow-agent-cursor/tsconfig.json

@@ -6,5 +6,5 @@
     "composite": true
   },
   "include": ["src/**/*.ts"],
-  "references": [{ "path": "../workflow" }]
+  "references": [{ "path": "../workflow" }, { "path": "../workflow-util-agent" }]
 }

packages/workflow-agent-hermes/__tests__/hermes-agent.test.ts

@@ -1,19 +1,5 @@
 import { describe, expect, test } from "bun:test";
-import { START, type ThreadContext } from "@uncaged/workflow";
-
-import { buildAgentPrompt, createHermesAgent, validateHermesAgentConfig } from "../src/index.js";
-
-function makeCtx(): ThreadContext {
-  return {
-    start: {
-      role: START,
-      content: "plan the migration",
-      meta: { maxRounds: 8 },
-      timestamp: 1,
-    },
-    steps: [],
-  };
-}
+import { createHermesAgent, validateHermesAgentConfig } from "../src/index.js";
 
 describe("validateHermesAgentConfig", () => {
   test("accepts valid config", () => {
@@ -36,14 +22,6 @@ describe("validateHermesAgentConfig", () => {
   });
 });
 
-describe("buildAgentPrompt", () => {
-  test("includes system and thread start", () => {
-    const text = buildAgentPrompt(makeCtx(), "You are a planner.");
-    expect(text).toContain("You are a planner.");
-    expect(text).toContain("plan the migration");
-  });
-});
-
 describe("createHermesAgent", () => {
   test("returns an AgentFn", () => {
     const agent = createHermesAgent({

packages/workflow-agent-hermes/package.json

@@ -9,6 +9,7 @@
     "test": "bun test"
   },
   "dependencies": {
-    "@uncaged/workflow": "workspace:*"
+    "@uncaged/workflow": "workspace:*",
+    "@uncaged/workflow-util-agent": "workspace:*"
   }
 }

packages/workflow-agent-hermes/src/build-agent-prompt.ts

@@ -1,17 +0,0 @@
-import type { ThreadContext } from "@uncaged/workflow";
-
-/** Combines the role system prompt with thread start content and prior role outputs. */
-export function buildAgentPrompt(ctx: ThreadContext, systemPrompt: string): string {
-  const blocks: string[] = [];
-  blocks.push("# System instructions");
-  blocks.push(systemPrompt);
-  blocks.push("");
-  blocks.push("# Thread");
-  blocks.push("## Start");
-  blocks.push(ctx.start.content);
-  for (const step of ctx.steps) {
-    blocks.push(`## Role: ${step.role}`);
-    blocks.push(step.content);
-  }
-  return blocks.join("\n");
-}

packages/workflow-agent-hermes/src/index.ts

@@ -1,13 +1,12 @@
 import type { AgentFn } from "@uncaged/workflow";
+import { buildAgentPrompt, type SpawnCliError, spawnCli } from "@uncaged/workflow-util-agent";
 
-import { buildAgentPrompt } from "./build-agent-prompt.js";
-import { type SpawnCliError, spawnCli } from "./spawn-cli.js";
 import type { HermesAgentConfig } from "./types.js";
 import { validateHermesAgentConfig } from "./validate-config.js";
 
 const HERMES_DEFAULT_MAX_TURNS = 90;
 
-export { buildAgentPrompt } from "./build-agent-prompt.js";
+export { buildAgentPrompt } from "@uncaged/workflow-util-agent";
 export type { HermesAgentConfig } from "./types.js";
 export { validateHermesAgentConfig } from "./validate-config.js";
 
@@ -36,7 +35,7 @@ export function createHermesAgent(config: HermesAgentConfig): AgentFn {
   const timeoutMs = config.timeout;
 
   return async (ctx, systemPrompt) => {
-    const fullPrompt = buildAgentPrompt(ctx, systemPrompt);
+    const fullPrompt = buildAgentPrompt(systemPrompt, ctx);
     const args = [
       "chat",
       "-q",

packages/workflow-agent-hermes/src/spawn-cli.ts

@@ -1,63 +0,0 @@
-import { spawn } from "node:child_process";
-
-import { err, ok, type Result } from "@uncaged/workflow";
-
-export type SpawnCliError =
-  | { kind: "non_zero_exit"; exitCode: number | null; stdout: string; stderr: string }
-  | { kind: "timeout" }
-  | { kind: "spawn_failed"; message: string };
-
-export function spawnCli(
-  command: string,
-  args: string[],
-  options: { cwd: string | null; timeoutMs: number | null },
-): Promise<Result<string, SpawnCliError>> {
-  return new Promise((resolve) => {
-    const child = spawn(command, args, {
-      cwd: options.cwd === null ? undefined : options.cwd,
-      shell: false,
-      stdio: ["ignore", "pipe", "pipe"],
-    });
-
-    let stdout = "";
-    let stderr = "";
-    child.stdout?.on("data", (chunk: Buffer) => {
-      stdout += chunk.toString();
-    });
-    child.stderr?.on("data", (chunk: Buffer) => {
-      stderr += chunk.toString();
-    });
-
-    let timedOut = false;
-    let timeoutId: ReturnType<typeof setTimeout> | null = null;
-    if (options.timeoutMs !== null) {
-      timeoutId = setTimeout(() => {
-        timedOut = true;
-        child.kill("SIGTERM");
-      }, options.timeoutMs);
-    }
-
-    child.on("error", (cause) => {
-      if (timeoutId !== null) {
-        clearTimeout(timeoutId);
-      }
-      const message = cause instanceof Error ? cause.message : String(cause);
-      resolve(err({ kind: "spawn_failed", message }));
-    });
-
-    child.on("close", (code) => {
-      if (timeoutId !== null) {
-        clearTimeout(timeoutId);
-      }
-      if (timedOut) {
-        resolve(err({ kind: "timeout" }));
-        return;
-      }
-      if (code === 0) {
-        resolve(ok(stdout));
-        return;
-      }
-      resolve(err({ kind: "non_zero_exit", exitCode: code, stdout, stderr }));
-    });
-  });
-}

packages/workflow-agent-hermes/tsconfig.json

@@ -6,5 +6,5 @@
     "composite": true
   },
   "include": ["src/**/*.ts"],
-  "references": [{ "path": "../workflow" }]
+  "references": [{ "path": "../workflow" }, { "path": "../workflow-util-agent" }]
 }

packages/workflow-util-agent/__tests__/build-agent-prompt.test.ts

@@ -0,0 +1,112 @@
+import { describe, expect, test } from "bun:test";
+import { START, type ThreadContext } from "@uncaged/workflow";
+
+import { buildAgentPrompt } from "../src/index.js";
+
+function startTask(content: string): ThreadContext["start"] {
+  return {
+    role: START,
+    content,
+    meta: { maxRounds: 5 },
+    timestamp: 1,
+  };
+}
+
+describe("buildAgentPrompt", () => {
+  test("includes system prompt and full task; omits tools when there are no steps", () => {
+    const ctx: ThreadContext = {
+      start: startTask("fix the bug"),
+      steps: [],
+    };
+    const text = buildAgentPrompt("You are an agent.", ctx);
+    expect(text).toContain("You are an agent.");
+    expect(text).toContain("## Task");
+    expect(text).toContain("fix the bug");
+    expect(text).not.toContain("## Tools");
+  });
+
+  test("single step shows full content and meta, and includes tools", () => {
+    const ctx: ThreadContext = {
+      start: startTask("user task"),
+      steps: [
+        {
+          role: "coder",
+          content: "only step full body",
+          meta: { files: ["a.ts"] },
+          timestamp: 2,
+        },
+      ],
+    };
+    const text = buildAgentPrompt("Be helpful.", ctx);
+    expect(text).toContain("## Task");
+    expect(text).toContain("user task");
+    expect(text).toContain("## Step: coder");
+    expect(text).toContain("only step full body");
+    expect(text).toContain('Meta: {"files":["a.ts"]}');
+    expect(text).toContain("## Tools");
+    expect(text).toContain("uncaged-workflow thread <threadId>");
+  });
+
+  test("two or more steps: previous steps are meta-only; latest step is full", () => {
+    const ctx: ThreadContext = {
+      start: startTask("first message full: task content here"),
+      steps: [
+        {
+          role: "planner",
+          content: "PLANNER_SECRET_FULL_TEXT",
+          meta: { plan: "short" },
+          timestamp: 2,
+        },
+        {
+          role: "coder",
+          content: "last step full content",
+          meta: { done: true },
+          timestamp: 3,
+        },
+      ],
+    };
+    const text = buildAgentPrompt("System.", ctx);
+    expect(text).toContain("first message full: task content here");
+    expect(text).toContain("## Previous Steps");
+    expect(text).toContain("### Step 1: planner");
+    expect(text).toContain('Summary: {"plan":"short"}');
+    expect(text).not.toContain("PLANNER_SECRET_FULL_TEXT");
+    expect(text).toContain("## Latest Step: coder");
+    expect(text).toContain("last step full content");
+    expect(text).toContain('Meta: {"done":true}');
+    expect(text).toContain("## Tools");
+  });
+
+  test("middle steps show meta summary only, not full content", () => {
+    const ctx: ThreadContext = {
+      start: startTask("start"),
+      steps: [
+        {
+          role: "a",
+          content: "HIDDEN_A",
+          meta: { n: 1 },
+          timestamp: 2,
+        },
+        {
+          role: "b",
+          content: "HIDDEN_B_MIDDLE",
+          meta: { n: 2 },
+          timestamp: 3,
+        },
+        {
+          role: "c",
+          content: "VISIBLE_LAST",
+          meta: { n: 3 },
+          timestamp: 4,
+        },
+      ],
+    };
+    const text = buildAgentPrompt("S", ctx);
+    expect(text).not.toContain("HIDDEN_A");
+    expect(text).not.toContain("HIDDEN_B_MIDDLE");
+    expect(text).toContain('Summary: {"n":1}');
+    expect(text).toContain('Summary: {"n":2}');
+    expect(text).toContain("VISIBLE_LAST");
+    expect(text).toContain("## Latest Step: c");
+  });
+});

packages/workflow-util-agent/__tests__/spawn-cli.test.ts

@@ -0,0 +1,39 @@
+import { describe, expect, test } from "bun:test";
+
+import { spawnCli } from "../src/index.js";
+
+const noTimeout = { cwd: null, timeoutMs: null } as const;
+
+describe("spawnCli", () => {
+  test("resolves ok stdout on zero exit", async () => {
+    const run = await spawnCli("echo", ["spawn-cli-ok"], { ...noTimeout });
+    expect(run.ok).toBe(true);
+    if (run.ok) {
+      expect(run.value.trim()).toBe("spawn-cli-ok");
+    }
+  });
+
+  test("resolves err on non-zero exit", async () => {
+    const run = await spawnCli("false", [], { ...noTimeout });
+    expect(run.ok).toBe(false);
+    if (!run.ok) {
+      expect(run.error.kind).toBe("non_zero_exit");
+    }
+  });
+
+  test("resolves err on timeout", async () => {
+    const run = await spawnCli("sleep", ["10"], { cwd: null, timeoutMs: 80 });
+    expect(run.ok).toBe(false);
+    if (!run.ok) {
+      expect(run.error.kind).toBe("timeout");
+    }
+  });
+
+  test("resolves err when spawn fails", async () => {
+    const run = await spawnCli("definitely-missing-executable-7f2a9c1b", [], { ...noTimeout });
+    expect(run.ok).toBe(false);
+    if (!run.ok) {
+      expect(run.error.kind).toBe("spawn_failed");
+    }
+  });
+});

packages/workflow-util-agent/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "@uncaged/workflow-util-agent",
+  "version": "0.1.0",
+  "type": "module",
+  "main": "src/index.ts",
+  "types": "src/index.ts",
+  "scripts": {
+    "build": "echo 'TODO'",
+    "test": "bun test"
+  },
+  "dependencies": {
+    "@uncaged/workflow": "workspace:*"
+  }
+}

packages/workflow-util-agent/src/build-agent-prompt.ts

@@ -0,0 +1,47 @@
+import type { ThreadContext } from "@uncaged/workflow";
+
+/** Builds the full agent prompt: system instructions plus summarized thread history. */
+export function buildAgentPrompt(systemPrompt: string, ctx: ThreadContext): string {
+  const lines: string[] = [];
+  lines.push(systemPrompt);
+  lines.push("");
+  lines.push("## Task");
+  lines.push(ctx.start.content);
+
+  const { steps } = ctx;
+  if (steps.length === 0) {
+    return lines.join("\n");
+  }
+
+  if (steps.length === 1) {
+    const s = steps[0];
+    lines.push("");
+    lines.push(`## Step: ${s.role}`);
+    lines.push("");
+    lines.push(s.content);
+    lines.push("");
+    lines.push(`Meta: ${JSON.stringify(s.meta)}`);
+  } else {
+    lines.push("");
+    lines.push("## Previous Steps");
+    for (let i = 0; i < steps.length - 1; i++) {
+      const s = steps[i];
+      lines.push("");
+      lines.push(`### Step ${i + 1}: ${s.role}`);
+      lines.push(`Summary: ${JSON.stringify(s.meta)}`);
+    }
+    const last = steps[steps.length - 1];
+    lines.push("");
+    lines.push(`## Latest Step: ${last.role}`);
+    lines.push("");
+    lines.push(last.content);
+    lines.push("");
+    lines.push(`Meta: ${JSON.stringify(last.meta)}`);
+  }
+
+  lines.push("");
+  lines.push("## Tools");
+  lines.push("Use `uncaged-workflow thread <threadId>` to read full details of any previous step.");
+
+  return lines.join("\n");
+}

packages/workflow-util-agent/src/index.ts

@@ -0,0 +1,3 @@
+export { buildAgentPrompt } from "./build-agent-prompt.js";
+export type { SpawnCliConfig, SpawnCliError, SpawnCliResult } from "./spawn-cli.js";
+export { spawnCli } from "./spawn-cli.js";

packages/workflow-util-agent/src/spawn-cli.ts

@@ -7,11 +7,18 @@ export type SpawnCliError =
   | { kind: "timeout" }
   | { kind: "spawn_failed"; message: string };
 
+export type SpawnCliConfig = {
+  cwd: string | null;
+  timeoutMs: number | null;
+};
+
+export type SpawnCliResult = Result<string, SpawnCliError>;
+
 export function spawnCli(
   command: string,
   args: string[],
-  options: { cwd: string | null; timeoutMs: number | null },
-): Promise<Result<string, SpawnCliError>> {
+  options: SpawnCliConfig,
+): Promise<SpawnCliResult> {
   return new Promise((resolve) => {
     const child = spawn(command, args, {
       cwd: options.cwd === null ? undefined : options.cwd,

packages/workflow-util-agent/tsconfig.json

@@ -0,0 +1,10 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "dist",
+    "composite": true
+  },
+  "include": ["src/**/*.ts"],
+  "references": [{ "path": "../workflow" }]
+}

tsconfig.json

@@ -22,6 +22,7 @@
     { "path": "packages/workflow-role-reviewer" },
     { "path": "packages/workflow-agent-cursor" },
     { "path": "packages/workflow-agent-hermes" },
+    { "path": "packages/workflow-util-agent" },
     { "path": "packages/cli-workflow" },
     { "path": "packages/workflow-template-solve-issue" }
   ]