refactor: align package folder names with npm package names

Rename packages/ subdirectories to match their @united-workforce/* scope:
  cli-workflow → cli
  workflow-agent-builtin → agent-builtin
  workflow-agent-claude-code → agent-claude-code
  workflow-agent-hermes → agent-hermes
  workflow-dashboard → dashboard
  workflow-protocol → protocol
  workflow-util-agent → util-agent
  workflow-util → util

Updated all tsconfig references, scripts, and active docs.
Historical docs (docs/plans/, docs/superpowers/) left as-is.

Closes #21

packages/agent-builtin/README.md

@@ -0,0 +1,141 @@
+# @united-workforce/agent-builtin
+
+`uwf-builtin` agent — built-in LLM agent with file read/write and shell tools.
+
+## Overview
+
+Layer 3 agent implementation. Runs an OpenAI-compatible chat completion loop with built-in tools (`read_file`, `write_file`, `run_command`). Uses the configured provider/model from `config.yaml`. Produces frontmatter markdown output and stores turn-by-turn session detail in CAS.
+
+Useful when you want a self-contained agent without an external CLI like Hermes or Claude Code.
+
+**Dependencies:** `@ocas/core`, `@united-workforce/util-agent`, `@united-workforce/util`
+
+## Installation
+
+Included as the `uwf-builtin` binary when you install `@united-workforce/agent-builtin`:
+
+```bash
+bun add -g @united-workforce/agent-builtin
+```
+
+## CLI Usage
+
+Invoked by `uwf thread step`:
+
+```bash
+uwf-builtin <thread-id> <role>
+```
+
+Configure as default agent:
+
+```bash
+uwf setup --agent builtin
+```
+
+Override per step:
+
+```bash
+uwf thread step <thread-id> --agent uwf-builtin
+```
+
+Environment variables set by the engine:
+
+| Variable | Purpose |
+|----------|---------|
+| `UWF_EDGE_PROMPT` | Moderator edge instruction for this step |
+
+## API
+
+All exports come from `src/index.ts`.
+
+### Agent factory
+
+```typescript
+function createBuiltinAgent(): () => Promise<void>
+function buildBuiltinMessages(ctx: AgentContext): ChatMessage[]
+```
+
+### LLM loop
+
+```typescript
+const BUILTIN_MAX_TURNS = 30;
+const BUILTIN_CONTINUE_MAX_TURNS = 5;
+
+function runBuiltinLoop(/* options: RunBuiltinLoopOptions */): Promise<RunBuiltinLoopResult>
+function chatCompletionWithTools(
+  provider: ResolvedLlmProvider,
+  messages: ChatMessage[],
+  tools: OpenAiToolDefinition[],
+): Promise<LlmAssistantResponse>
+```
+
+`RunBuiltinLoopOptions` and `RunBuiltinLoopResult` are internal to `loop.ts` and not re-exported from `index.ts`.
+
+### Tools
+
+```typescript
+function getBuiltinTools(): readonly BuiltinTool[]
+function executeBuiltinTool(
+  name: string,
+  args: Record<string, unknown>,
+  ctx: ToolContext,
+): Promise<string>
+```
+
+### Session and detail
+
+```typescript
+function initSessionDir(storageRoot: string): Promise<void>
+function appendSessionTurn(storageRoot: string, sessionId: string, turn: BuiltinTurnPayload): Promise<void>
+function readSessionTurns(storageRoot: string, sessionId: string): Promise<BuiltinTurnPayload[]>
+function removeSession(storageRoot: string, sessionId: string): Promise<void>
+function registerBuiltinSchemas(store: Store): Promise<BuiltinSchemaHashes>
+function storeBuiltinDetail(store: Store, payload: BuiltinDetailPayload): Promise<string>
+```
+
+### Types
+
+```typescript
+type ChatMessage = /* system | user | assistant | tool */;
+type LlmAssistantResponse = { content: string | null; toolCalls: LlmToolCall[] | null };
+type LlmToolCall = { id: string; name: string; arguments: string };
+type BuiltinTool = { name: string; description: string; parameters: Record<string, unknown> };
+type ToolContext = { cwd: string; storageRoot: string };
+type BuiltinDetailPayload = { /* session turns, model, timestamps */ };
+type BuiltinLoopTurn = { /* single loop iteration record */ };
+type BuiltinToolCallRecord = { /* tool call audit */ };
+type BuiltinToolResultRecord = { /* tool result audit */ };
+type BuiltinTurnPayload = { /* persisted turn */ };
+```
+
+## Internal Structure
+
+```
+src/
+├── index.ts
+├── cli.ts              Binary entrypoint
+├── agent.ts            createBuiltinAgent
+├── loop.ts             Multi-turn LLM + tool loop
+├── prompt.ts           buildBuiltinMessages
+├── session.ts          Session directory persistence
+├── detail.ts           CAS detail node storage
+├── schemas.ts          Builtin CAS schemas
+├── types.ts            Detail and turn payload types
+├── llm/
+│   ├── index.ts
+│   ├── llm.ts          chatCompletionWithTools
+│   └── types.ts        ChatMessage, LlmToolCall, etc.
+└── tools/
+    ├── index.ts        getBuiltinTools, executeBuiltinTool
+    ├── read-file.ts
+    ├── write-file.ts
+    ├── run-command.ts
+    ├── path.ts
+    └── types.ts
+```
+
+## Configuration
+
+Requires a configured OpenAI-compatible provider and model in `~/.uncaged/workflow/config.yaml` (via `uwf setup`). API keys are loaded from `~/.uncaged/workflow/.env`.
+
+Tools run with the current working directory as `ToolContext.cwd` (typically the directory where `uwf thread step` was invoked).

packages/agent-builtin/__tests__/llm-parse.test.ts

@@ -0,0 +1,16 @@
+import { describe, expect, test } from "bun:test";
+
+import type { LlmToolCall } from "../src/llm/types.js";
+
+/** Mirror OpenAI response shape for parser coverage via chatCompletionWithTools integration later. */
+describe("LlmToolCall shape", () => {
+  test("tool call record fields", () => {
+    const call: LlmToolCall = {
+      id: "call_1",
+      name: "read_file",
+      arguments: '{"path":"README.md"}',
+    };
+    expect(call.name).toBe("read_file");
+    expect(JSON.parse(call.arguments)).toEqual({ path: "README.md" });
+  });
+});

packages/agent-builtin/__tests__/loop.test.ts

@@ -0,0 +1,256 @@
+import { beforeEach, describe, expect, mock, test } from "bun:test";
+
+const mockChatCompletionWithTools = mock(async () => ({
+  content: "---\nstatus: done\n---",
+  toolCalls: [],
+}));
+const mockAppendSessionTurn = mock(async () => {});
+const mockExecuteBuiltinTool = mock(async () => "tool-result");
+
+mock.module("../src/llm/index.js", () => ({
+  chatCompletionWithTools: mockChatCompletionWithTools,
+}));
+mock.module("../src/session.js", () => ({
+  appendSessionTurn: mockAppendSessionTurn,
+}));
+mock.module("../src/tools/index.js", () => ({
+  builtinToolsToOpenAi: () => [],
+  executeBuiltinTool: mockExecuteBuiltinTool,
+  getBuiltinTools: () => [],
+}));
+
+import {
+  executeTurnTools,
+  extractFinalText,
+  runBuiltinLoop,
+  shouldInjectDeadlineWarning,
+  shouldNudge,
+  shouldProcessToolCalls,
+} from "../src/loop.js";
+
+const fakeProvider = {} as any;
+const fakeToolCtx = {} as any;
+
+function makeOptions(overrides: Partial<Parameters<typeof runBuiltinLoop>[0]> = {}) {
+  return {
+    provider: fakeProvider,
+    messages: [{ role: "system" as const, content: "sys" }],
+    toolCtx: fakeToolCtx,
+    maxTurns: 5,
+    storageRoot: "/tmp",
+    sessionId: "sess",
+    noTools: false,
+    ...overrides,
+  };
+}
+
+beforeEach(() => {
+  mockChatCompletionWithTools.mockReset();
+  mockAppendSessionTurn.mockReset();
+  mockExecuteBuiltinTool.mockReset();
+});
+
+describe("shouldNudge", () => {
+  test("2.1 returns true when all conditions met", () => {
+    expect(shouldNudge({ noTools: false, text: "some text", turn: 0, maxTurns: 5 })).toBe(true);
+  });
+  test("2.2 returns false when noTools=true", () => {
+    expect(shouldNudge({ noTools: true, text: "some text", turn: 0, maxTurns: 5 })).toBe(false);
+  });
+  test("2.3 returns false when text starts with ---", () => {
+    expect(shouldNudge({ noTools: false, text: "---\nstatus: done", turn: 0, maxTurns: 5 })).toBe(
+      false,
+    );
+  });
+  test("2.4 returns false on last turn", () => {
+    expect(shouldNudge({ noTools: false, text: "some text", turn: 4, maxTurns: 5 })).toBe(false);
+  });
+  test("2.5 returns true on second-to-last turn", () => {
+    expect(shouldNudge({ noTools: false, text: "some text", turn: 3, maxTurns: 5 })).toBe(true);
+  });
+  test("2.6 leading whitespace before --- suppresses nudge", () => {
+    expect(shouldNudge({ noTools: false, text: "  ---\nstatus: done", turn: 0, maxTurns: 5 })).toBe(
+      false,
+    );
+  });
+});
+
+describe("executeTurnTools", () => {
+  test("4.1 executes each tool call and pushes tool result messages", async () => {
+    mockExecuteBuiltinTool.mockResolvedValue("result");
+    const messages: any[] = [];
+    const calls = [
+      { id: "c1", name: "tool_a", arguments: "{}" },
+      { id: "c2", name: "tool_b", arguments: "{}" },
+    ];
+    const count = await executeTurnTools(calls, fakeToolCtx, messages, "/tmp", "sess");
+    expect(messages.length).toBe(2);
+    expect(messages[0].role).toBe("tool");
+    expect(messages[1].role).toBe("tool");
+    expect(count).toBe(2);
+  });
+  test("4.2 tool result content matches executeBuiltinTool return value", async () => {
+    mockExecuteBuiltinTool.mockResolvedValue("result-A");
+    const messages: any[] = [];
+    await executeTurnTools(
+      [{ id: "c1", name: "read_file", arguments: "{}" }],
+      fakeToolCtx,
+      messages,
+      "/tmp",
+      "sess",
+    );
+    expect(messages[0].content).toBe("result-A");
+  });
+});
+
+describe("runBuiltinLoop integration", () => {
+  test("3.1 single text-only response returns finalText immediately", async () => {
+    mockChatCompletionWithTools.mockResolvedValue({
+      content: "---\nstatus: done\n---",
+      toolCalls: [],
+    });
+    const result = await runBuiltinLoop(makeOptions());
+    expect(result.finalText).toBe("---\nstatus: done\n---");
+    expect(result.turnCount).toBe(1);
+  });
+  test("3.2 noTools=true suppresses tool calls", async () => {
+    mockChatCompletionWithTools.mockResolvedValue({
+      content: "ok",
+      toolCalls: [{ id: "c1", name: "read_file", arguments: "{}" }],
+    });
+    const result = await runBuiltinLoop(makeOptions({ noTools: true }));
+    expect(result.finalText).toBe("ok");
+    expect(result.turnCount).toBe(1);
+  });
+  test("3.3 tool call followed by text response", async () => {
+    mockChatCompletionWithTools
+      .mockResolvedValueOnce({
+        content: null,
+        toolCalls: [{ id: "c1", name: "read_file", arguments: "{}" }],
+      })
+      .mockResolvedValueOnce({ content: "---\nstatus: done\n---", toolCalls: [] });
+    mockExecuteBuiltinTool.mockResolvedValue("file contents");
+    const result = await runBuiltinLoop(makeOptions());
+    expect(result.finalText).toBe("---\nstatus: done\n---");
+    expect(result.turnCount).toBe(3);
+  });
+  test("3.4 nudge cycle inserts nudge message", async () => {
+    mockChatCompletionWithTools
+      .mockResolvedValueOnce({ content: "I am thinking", toolCalls: [] })
+      .mockResolvedValueOnce({ content: "---\nstatus: done\n---", toolCalls: [] });
+    const result = await runBuiltinLoop(makeOptions());
+    expect(result.finalText).toBe("---\nstatus: done\n---");
+    const nudgeMsg = result.messages.find(
+      (m) =>
+        m.role === "user" && typeof m.content === "string" && m.content.includes("frontmatter"),
+    );
+    expect(nudgeMsg).toBeDefined();
+  });
+  test("3.5 maxTurns exhaustion falls back to last assistant content", async () => {
+    mockChatCompletionWithTools.mockResolvedValue({ content: "still thinking", toolCalls: [] });
+    const result = await runBuiltinLoop(makeOptions({ maxTurns: 3 }));
+    expect(result.finalText).toBe("still thinking");
+  });
+  test("3.6 original messages array is not mutated", async () => {
+    mockChatCompletionWithTools.mockResolvedValue({
+      content: "---\nstatus: done\n---",
+      toolCalls: [],
+    });
+    const original = [{ role: "system" as const, content: "sys" }];
+    await runBuiltinLoop(makeOptions({ messages: original }));
+    expect(original.length).toBe(1);
+  });
+});
+
+describe("shouldInjectDeadlineWarning", () => {
+  test("5.1 returns true when turn count reaches warning threshold and not yet warned", () => {
+    expect(shouldInjectDeadlineWarning(7, 10, false, false)).toBe(true);
+  });
+  test("5.2 returns false when already warned", () => {
+    expect(shouldInjectDeadlineWarning(7, 10, true, false)).toBe(false);
+  });
+  test("5.3 returns false when noTools is true", () => {
+    expect(shouldInjectDeadlineWarning(7, 10, false, true)).toBe(false);
+  });
+  test("5.4 returns false when turns remaining > DEADLINE_WARNING_TURNS", () => {
+    expect(shouldInjectDeadlineWarning(5, 10, false, false)).toBe(false);
+  });
+  test("5.5 returns true when exactly at warning threshold", () => {
+    expect(shouldInjectDeadlineWarning(7, 10, false, false)).toBe(true);
+  });
+  test("5.6 returns false when turns remaining is 0", () => {
+    expect(shouldInjectDeadlineWarning(10, 10, false, false)).toBe(false);
+  });
+});
+
+describe("shouldProcessToolCalls", () => {
+  test("6.1 returns true when toolCalls present and noTools=false", () => {
+    expect(shouldProcessToolCalls([{ id: "x", name: "read", arguments: "{}" }], false)).toBe(true);
+  });
+  test("6.2 returns false when toolCalls is null", () => {
+    expect(shouldProcessToolCalls(null, false)).toBe(false);
+  });
+  test("6.3 returns false when toolCalls is empty array", () => {
+    expect(shouldProcessToolCalls([], false)).toBe(false);
+  });
+  test("6.4 returns false when noTools=true", () => {
+    expect(shouldProcessToolCalls([{ id: "x", name: "read", arguments: "{}" }], true)).toBe(false);
+  });
+  test("6.5 returns true when multiple tool calls present", () => {
+    expect(
+      shouldProcessToolCalls(
+        [
+          { id: "x1", name: "read", arguments: "{}" },
+          { id: "x2", name: "write", arguments: "{}" },
+        ],
+        false,
+      ),
+    ).toBe(true);
+  });
+});
+
+describe("extractFinalText", () => {
+  test("7.1 returns last assistant message content", () => {
+    const messages = [
+      { role: "system" as const, content: "sys", tool_calls: null },
+      { role: "assistant" as const, content: "first", tool_calls: null },
+      { role: "assistant" as const, content: "last", tool_calls: null },
+    ];
+    expect(extractFinalText(messages)).toBe("last");
+  });
+  test("7.2 returns empty string when no assistant messages", () => {
+    expect(extractFinalText([{ role: "system" as const, content: "sys", tool_calls: null }])).toBe(
+      "",
+    );
+  });
+  test("7.3 skips assistant messages with null content", () => {
+    const messages = [
+      { role: "assistant" as const, content: "first", tool_calls: null },
+      {
+        role: "assistant" as const,
+        content: null,
+        tool_calls: [{ id: "x", name: "t", arguments: "{}" }],
+      },
+      { role: "assistant" as const, content: "second", tool_calls: null },
+    ];
+    expect(extractFinalText(messages)).toBe("second");
+  });
+  test("7.4 skips assistant messages with empty content", () => {
+    const messages = [
+      { role: "assistant" as const, content: "first", tool_calls: null },
+      { role: "assistant" as const, content: "", tool_calls: null },
+      { role: "user" as const, content: "nudge", tool_calls: null },
+    ];
+    expect(extractFinalText(messages)).toBe("first");
+  });
+  test("7.5 handles empty messages array", () => {
+    expect(extractFinalText([])).toBe("");
+  });
+  test("7.6 handles messages with only user and system roles", () => {
+    const messages = [
+      { role: "system" as const, content: "sys", tool_calls: null },
+      { role: "user" as const, content: "query", tool_calls: null },
+    ];
+    expect(extractFinalText(messages)).toBe("");
+  });
+});

packages/agent-builtin/__tests__/path.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, test } from "bun:test";
+import { resolve } from "node:path";
+import { resolvePath } from "../src/tools/path.js";
+
+describe("resolvePath", () => {
+  test("resolves relative paths against cwd", () => {
+    const root = "/workspace/project";
+    const resolved = resolvePath(root, "src/foo.ts");
+    expect(resolved).toBe(resolve(root, "src/foo.ts"));
+  });
+
+  test("resolves absolute paths as-is", () => {
+    const resolved = resolvePath("/workspace", "/etc/hosts");
+    expect(resolved).toBe("/etc/hosts");
+  });
+
+  test("resolves parent traversal normally", () => {
+    const resolved = resolvePath("/workspace/project", "../other/file.ts");
+    expect(resolved).toBe(resolve("/workspace/project", "../other/file.ts"));
+  });
+});

packages/agent-builtin/__tests__/prompt.test.ts

@@ -0,0 +1,236 @@
+import { describe, expect, test } from "bun:test";
+
+import type { AgentContext } from "@united-workforce/util-agent";
+
+import { buildBuiltinMessages } from "../src/prompt.js";
+
+function minimalContext(overrides: Partial<AgentContext> = {}): AgentContext {
+  return {
+    threadId: "00000000000000000000000000" as AgentContext["threadId"],
+    role: "developer",
+    store: {} as AgentContext["store"],
+    workflow: {
+      name: "test",
+      description: "test workflow",
+      roles: {
+        developer: {
+          description: "Developer role",
+          goal: "Ship the fix",
+          capabilities: ["file-edit"],
+          procedure: "Edit files",
+          output: "A patch",
+          frontmatter: "schema-hash",
+        },
+      },
+      conditions: {},
+      graph: {},
+    },
+    start: { workflow: "wf-hash", prompt: "Fix the bug" },
+    steps: [],
+    outputFormatInstruction: "---\nstatus: done\n---",
+    edgePrompt: "Implement the fix described in the plan.",
+    isFirstVisit: true,
+    ...overrides,
+  };
+}
+
+describe("buildBuiltinMessages", () => {
+  test("system includes output format and role goal", () => {
+    const messages = buildBuiltinMessages(minimalContext());
+    const system = messages[0];
+    expect(system?.role).toBe("system");
+    if (system?.role === "system") {
+      expect(system.content).toContain("status: done");
+      expect(system.content).toContain("## Goal");
+      expect(system.content).toContain("Ship the fix");
+    }
+  });
+
+  test("first visit produces system + single user message with edge prompt", () => {
+    const messages = buildBuiltinMessages(minimalContext());
+    expect(messages).toHaveLength(2);
+    expect(messages[1]?.role).toBe("user");
+    if (messages[1]?.role === "user") {
+      expect(messages[1].content).toContain("Implement the fix");
+      expect(messages[1].content).not.toContain("## What Happened Since Your Last Turn");
+    }
+  });
+
+  test("first visit with prior steps includes inter-step summary in final user message", () => {
+    const messages = buildBuiltinMessages(
+      minimalContext({
+        steps: [
+          {
+            role: "planner",
+            output: { plan: "step 1" },
+            agent: "uwf-builtin",
+            detail: "detail-hash",
+            edgePrompt: "Create a plan.",
+          },
+        ],
+      }),
+    );
+    expect(messages).toHaveLength(2);
+    const finalUser = messages[1];
+    if (finalUser?.role === "user") {
+      expect(finalUser.content).toContain("Implement the fix");
+      expect(finalUser.content).toContain("## What Happened Since Your Last Turn");
+      expect(finalUser.content).toContain("planner");
+    }
+  });
+
+  test("re-entry reconstructs prior user/assistant turns plus current user message", () => {
+    const messages = buildBuiltinMessages(
+      minimalContext({
+        isFirstVisit: false,
+        edgePrompt: "Fix the reviewer's feedback.",
+        steps: [
+          {
+            role: "developer",
+            output: { summary: "Initial fix" },
+            agent: "uwf-builtin",
+            detail: "detail-1",
+            edgePrompt: "Implement the fix.",
+          },
+          {
+            role: "reviewer",
+            output: { approved: false, comments: "Missing tests" },
+            agent: "uwf-builtin",
+            detail: "detail-2",
+            edgePrompt: "Review the implementation.",
+          },
+        ],
+      }),
+    );
+
+    expect(messages).toHaveLength(4);
+    expect(messages[0]?.role).toBe("system");
+    expect(messages[1]?.role).toBe("user");
+    expect(messages[2]?.role).toBe("assistant");
+    expect(messages[3]?.role).toBe("user");
+
+    if (messages[1]?.role === "user") {
+      expect(messages[1].content).toBe("Implement the fix.");
+    }
+    if (messages[2]?.role === "assistant") {
+      expect(messages[2].content).toBe(JSON.stringify({ summary: "Initial fix" }));
+    }
+    if (messages[3]?.role === "user") {
+      expect(messages[3].content).toContain("Fix the reviewer's feedback.");
+      expect(messages[3].content).toContain("## What Happened Since Your Last Turn");
+      expect(messages[3].content).toContain("reviewer");
+      expect(messages[3].content).toContain("Missing tests");
+    }
+  });
+
+  test("prefix is stable across re-entry for LLM cache hits", () => {
+    const firstVisitMessages = buildBuiltinMessages(
+      minimalContext({
+        edgePrompt: "Implement the fix.",
+        steps: [],
+      }),
+    );
+
+    const reEntryMessages = buildBuiltinMessages(
+      minimalContext({
+        isFirstVisit: false,
+        edgePrompt: "Fix the reviewer's feedback.",
+        steps: [
+          {
+            role: "developer",
+            output: { summary: "Initial fix" },
+            agent: "uwf-builtin",
+            detail: "detail-1",
+            edgePrompt: "Implement the fix.",
+          },
+          {
+            role: "reviewer",
+            output: { approved: false },
+            agent: "uwf-builtin",
+            detail: "detail-2",
+            edgePrompt: "Review the code.",
+          },
+        ],
+      }),
+    );
+
+    expect(reEntryMessages[0]).toEqual(firstVisitMessages[0]);
+    expect(reEntryMessages[1]).toEqual(firstVisitMessages[1]);
+    expect(reEntryMessages[2]?.role).toBe("assistant");
+    if (reEntryMessages[2]?.role === "assistant") {
+      expect(reEntryMessages[2].content).toBe(JSON.stringify({ summary: "Initial fix" }));
+    }
+    expect(reEntryMessages[3]?.role).toBe("user");
+    if (reEntryMessages[3]?.role === "user") {
+      expect(reEntryMessages[3].content).toContain("Fix the reviewer's feedback.");
+    }
+  });
+
+  test("multiple prior visits emit one user/assistant pair per visit", () => {
+    const messages = buildBuiltinMessages(
+      minimalContext({
+        isFirstVisit: false,
+        edgePrompt: "Third round fix.",
+        steps: [
+          {
+            role: "developer",
+            output: { round: 1 },
+            agent: "uwf-builtin",
+            detail: "d1",
+            edgePrompt: "First attempt.",
+          },
+          {
+            role: "reviewer",
+            output: { approved: false },
+            agent: "uwf-builtin",
+            detail: "d2",
+            edgePrompt: "Review round 1.",
+          },
+          {
+            role: "developer",
+            output: { round: 2 },
+            agent: "uwf-builtin",
+            detail: "d3",
+            edgePrompt: "Second attempt.",
+          },
+          {
+            role: "reviewer",
+            output: { approved: false },
+            agent: "uwf-builtin",
+            detail: "d4",
+            edgePrompt: "Review round 2.",
+          },
+        ],
+      }),
+    );
+
+    expect(messages).toHaveLength(6);
+    expect(messages.map((m) => m.role)).toEqual([
+      "system",
+      "user",
+      "assistant",
+      "user",
+      "assistant",
+      "user",
+    ]);
+
+    if (messages[1]?.role === "user") {
+      expect(messages[1].content).toBe("First attempt.");
+    }
+    if (messages[2]?.role === "assistant") {
+      expect(messages[2].content).toBe(JSON.stringify({ round: 1 }));
+    }
+    if (messages[3]?.role === "user") {
+      expect(messages[3].content).toContain("Second attempt.");
+      expect(messages[3].content).toContain("reviewer");
+    }
+    if (messages[4]?.role === "assistant") {
+      expect(messages[4].content).toBe(JSON.stringify({ round: 2 }));
+    }
+    if (messages[5]?.role === "user") {
+      expect(messages[5].content).toContain("Third round fix.");
+      expect(messages[5].content).toContain("### Step 4: reviewer");
+      expect(messages[5].content).toContain('"approved":false');
+    }
+  });
+});

packages/agent-builtin/package.json

@@ -0,0 +1,46 @@
+{
+  "name": "@united-workforce/agent-builtin",
+  "version": "0.5.0",
+  "files": [
+    "src",
+    "dist",
+    "package.json"
+  ],
+  "type": "module",
+  "bin": {
+    "uwf-builtin": "./src/cli.ts"
+  },
+  "exports": {
+    ".": {
+      "bun": "./src/index.ts",
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js"
+    }
+  },
+  "scripts": {
+    "prepublishOnly": "echo 'Use bun run release from repo root' && exit 1",
+    "test": "bun test __tests__/",
+    "test:ci": "bun test __tests__/"
+  },
+  "dependencies": {
+    "@ocas/core": "^0.1.1",
+    "@united-workforce/util-agent": "workspace:^",
+    "@united-workforce/util": "workspace:^"
+  },
+  "devDependencies": {
+    "typescript": "^5.8.3"
+  },
+  "publishConfig": {
+    "access": "public"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://git.shazhou.work/uncaged/workflow.git",
+    "directory": "packages/agent-builtin"
+  },
+  "homepage": "https://git.shazhou.work/uncaged/workflow#readme",
+  "bugs": {
+    "url": "https://git.shazhou.work/uncaged/workflow/issues"
+  },
+  "license": "MIT"
+}

packages/agent-builtin/src/agent.ts

@@ -0,0 +1,163 @@
+import type { Store } from "@ocas/core";
+import { createLogger, generateUlid } from "@united-workforce/util";
+import {
+  type AgentContext,
+  type AgentRunResult,
+  createAgent,
+  loadWorkflowConfig,
+  resolveModel,
+  resolveStorageRoot,
+} from "@united-workforce/util-agent";
+
+import { storeBuiltinDetail } from "./detail.js";
+import type { ChatMessage } from "./llm/index.js";
+import { BUILTIN_CONTINUE_MAX_TURNS, BUILTIN_MAX_TURNS, runBuiltinLoop } from "./loop.js";
+import { buildBuiltinMessages } from "./prompt.js";
+import { initSessionDir } from "./session.js";
+
+const log = createLogger({ sink: { kind: "stderr" } });
+
+const FRONTMATTER_FENCE = "---";
+
+/**
+ * Strip any text before the first `---` fence.
+ * LLMs sometimes emit preamble text before the frontmatter block.
+ */
+function stripPreamble(text: string): string {
+  if (text.startsWith(FRONTMATTER_FENCE)) {
+    return text;
+  }
+  const idx = text.indexOf(`\n${FRONTMATTER_FENCE}\n`);
+  if (idx !== -1) {
+    log("6GWRP3QX", `stripped ${idx + 1} chars of preamble before frontmatter`);
+    return text.slice(idx + 1);
+  }
+  return text;
+}
+
+type SessionRecord = {
+  sessionId: string;
+  model: string;
+  startedAtMs: number;
+  messages: ChatMessage[];
+};
+
+const sessions = new Map<string, SessionRecord>();
+
+function getSession(sessionId: string): SessionRecord {
+  const session = sessions.get(sessionId);
+  if (session === undefined) {
+    throw new Error(`builtin session not found: ${sessionId}`);
+  }
+  return session;
+}
+
+function buildToolContext(storageRoot: string): { cwd: string; storageRoot: string } {
+  return {
+    cwd: process.cwd(),
+    storageRoot,
+  };
+}
+
+async function runBuiltinWithMessages(
+  storageRoot: string,
+  provider: ReturnType<typeof resolveModel>,
+  messages: ChatMessage[],
+  session: SessionRecord,
+  store: Store,
+  maxTurns: number,
+  noTools: boolean,
+): Promise<AgentRunResult> {
+  const loopResult = await runBuiltinLoop({
+    provider,
+    messages,
+    toolCtx: buildToolContext(storageRoot),
+    maxTurns,
+    storageRoot,
+    sessionId: session.sessionId,
+    noTools,
+  });
+
+  session.messages = loopResult.messages;
+
+  if (loopResult.turnCount === 0) {
+    log("5RWTK9NB", "no turns produced, returning empty output");
+    return { output: "", detailHash: "", sessionId: session.sessionId, assembledPrompt: "" };
+  }
+
+  // Read jsonl → persist turns to CAS → store detail
+  const { detailHash } = await storeBuiltinDetail(
+    store,
+    storageRoot,
+    session.sessionId,
+    session.model,
+    session.startedAtMs,
+  );
+
+  return {
+    output: stripPreamble(loopResult.finalText),
+    detailHash,
+    sessionId: session.sessionId,
+    assembledPrompt: "",
+  };
+}
+
+async function runBuiltin(ctx: AgentContext): Promise<AgentRunResult> {
+  const storageRoot = resolveStorageRoot();
+  const config = await loadWorkflowConfig(storageRoot);
+  const provider = resolveModel(config, config.defaultModel);
+
+  const sessionId = generateUlid(Date.now());
+  await initSessionDir(storageRoot);
+  const messages = buildBuiltinMessages(ctx);
+
+  const session: SessionRecord = {
+    sessionId,
+    model: provider.model,
+    startedAtMs: Date.now(),
+    messages,
+  };
+  sessions.set(sessionId, session);
+
+  return runBuiltinWithMessages(
+    storageRoot,
+    provider,
+    messages,
+    session,
+    ctx.store,
+    BUILTIN_MAX_TURNS,
+    false,
+  );
+}
+
+async function continueBuiltin(
+  sessionId: string,
+  message: string,
+  store: Store,
+): Promise<AgentRunResult> {
+  const session = getSession(sessionId);
+  const storageRoot = resolveStorageRoot();
+  const config = await loadWorkflowConfig(storageRoot);
+  const provider = resolveModel(config, config.defaultModel);
+
+  const messages: ChatMessage[] = [...session.messages, { role: "user", content: message }];
+
+  return runBuiltinWithMessages(
+    storageRoot,
+    provider,
+    messages,
+    session,
+    store,
+    BUILTIN_CONTINUE_MAX_TURNS,
+    true,
+  );
+}
+
+/** Agent CLI factory: built-in LLM loop with file/shell tools. */
+export function createBuiltinAgent(): () => Promise<void> {
+  return createAgent({
+    name: "builtin",
+    run: runBuiltin,
+    continue: continueBuiltin,
+  });
+}

packages/agent-builtin/src/cli.ts

@@ -0,0 +1,6 @@
+#!/usr/bin/env bun
+
+import { createBuiltinAgent } from "./agent.js";
+
+const main = createBuiltinAgent();
+void main();

packages/agent-builtin/src/detail.ts

@@ -0,0 +1,49 @@
+import { bootstrap, putSchema, type Store } from "@ocas/core";
+
+import { BUILTIN_DETAIL_SCHEMA, BUILTIN_TURN_SCHEMA } from "./schemas.js";
+import { readSessionTurns } from "./session.js";
+import type { BuiltinDetailPayload } from "./types.js";
+
+type BuiltinSchemaHashes = {
+  turn: string;
+  detail: string;
+};
+
+export async function registerBuiltinSchemas(store: Store): Promise<BuiltinSchemaHashes> {
+  await bootstrap(store);
+  const [turn, detail] = await Promise.all([
+    putSchema(store, BUILTIN_TURN_SCHEMA),
+    putSchema(store, BUILTIN_DETAIL_SCHEMA),
+  ]);
+  return { turn, detail };
+}
+
+/** Read session jsonl, persist each turn to CAS, return detail hash. */
+export async function storeBuiltinDetail(
+  store: Store,
+  storageRoot: string,
+  sessionId: string,
+  model: string,
+  startedAtMs: number,
+  nowMs: number = Date.now(),
+): Promise<{ detailHash: string; turnCount: number }> {
+  const schemas = await registerBuiltinSchemas(store);
+  const turns = await readSessionTurns(storageRoot, sessionId);
+
+  const turnHashes: string[] = [];
+  for (const turn of turns) {
+    const hash = await store.put(schemas.turn, turn);
+    turnHashes.push(hash);
+  }
+
+  const duration = Math.max(0, nowMs - startedAtMs);
+  const detail: BuiltinDetailPayload = {
+    sessionId,
+    model,
+    duration,
+    turnCount: turnHashes.length,
+    turns: turnHashes,
+  };
+  const detailHash = await store.put(schemas.detail, detail);
+  return { detailHash, turnCount: turnHashes.length };
+}

packages/agent-builtin/src/index.ts

@@ -0,0 +1,16 @@
+export { createBuiltinAgent } from "./agent.js";
+export { registerBuiltinSchemas, storeBuiltinDetail } from "./detail.js";
+export type { ChatMessage, LlmAssistantResponse, LlmToolCall } from "./llm/index.js";
+export { chatCompletionWithTools } from "./llm/index.js";
+export { BUILTIN_CONTINUE_MAX_TURNS, BUILTIN_MAX_TURNS, runBuiltinLoop } from "./loop.js";
+export { buildBuiltinMessages } from "./prompt.js";
+export { appendSessionTurn, initSessionDir, readSessionTurns, removeSession } from "./session.js";
+export type { BuiltinTool, ToolContext } from "./tools/index.js";
+export { executeBuiltinTool, getBuiltinTools } from "./tools/index.js";
+export type {
+  BuiltinDetailPayload,
+  BuiltinLoopTurn,
+  BuiltinToolCallRecord,
+  BuiltinToolResultRecord,
+  BuiltinTurnPayload,
+} from "./types.js";

packages/agent-builtin/src/llm/index.ts

@@ -0,0 +1,7 @@
+export { chatCompletionWithTools } from "./llm.js";
+export type {
+  ChatMessage,
+  LlmAssistantResponse,
+  LlmToolCall,
+  OpenAiToolDefinition,
+} from "./types.js";

packages/agent-builtin/src/llm/llm.ts

@@ -0,0 +1,139 @@
+import type { ResolvedLlmProvider } from "@united-workforce/util-agent";
+
+import type {
+  ChatMessage,
+  LlmAssistantResponse,
+  LlmToolCall,
+  OpenAiToolDefinition,
+} from "./types.js";
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null && !Array.isArray(value);
+}
+
+function chatUrl(baseUrl: string): string {
+  const trimmed = baseUrl.replace(/\/+$/, "");
+  return `${trimmed}/chat/completions`;
+}
+
+function parseToolCalls(raw: unknown): LlmToolCall[] | null {
+  if (!Array.isArray(raw) || raw.length === 0) {
+    return null;
+  }
+  const calls: LlmToolCall[] = [];
+  for (const entry of raw) {
+    if (!isRecord(entry)) {
+      continue;
+    }
+    const id = entry.id;
+    const fn = entry.function;
+    if (typeof id !== "string" || !isRecord(fn)) {
+      continue;
+    }
+    const name = fn.name;
+    const args = fn.arguments;
+    if (typeof name !== "string" || typeof args !== "string") {
+      continue;
+    }
+    calls.push({ id, name, arguments: args });
+  }
+  return calls.length > 0 ? calls : null;
+}
+
+function parseAssistantMessage(parsed: unknown): LlmAssistantResponse {
+  if (!isRecord(parsed)) {
+    throw new Error("LLM response is not an object");
+  }
+  const choices = parsed.choices;
+  if (!Array.isArray(choices) || choices.length === 0) {
+    throw new Error("LLM response has no choices");
+  }
+  const c0 = choices[0];
+  if (!isRecord(c0)) {
+    throw new Error("LLM choice is not an object");
+  }
+  const messageObj = c0.message;
+  if (!isRecord(messageObj)) {
+    throw new Error("LLM message is not an object");
+  }
+  const contentRaw = messageObj.content;
+  const content =
+    typeof contentRaw === "string"
+      ? contentRaw
+      : contentRaw === null || contentRaw === undefined
+        ? null
+        : null;
+  const toolCalls = parseToolCalls(messageObj.tool_calls);
+  return { content, toolCalls };
+}
+
+function serializeMessage(message: ChatMessage): Record<string, unknown> {
+  if (message.role === "tool") {
+    return {
+      role: "tool",
+      tool_call_id: message.tool_call_id,
+      content: message.content,
+    };
+  }
+  if (message.role === "assistant") {
+    const base: Record<string, unknown> = {
+      role: "assistant",
+      content: message.content,
+    };
+    if (message.tool_calls !== null && message.tool_calls.length > 0) {
+      base.tool_calls = message.tool_calls.map((call) => ({
+        id: call.id,
+        type: "function",
+        function: { name: call.name, arguments: call.arguments },
+      }));
+    }
+    return base;
+  }
+  return { role: message.role, content: message.content };
+}
+
+/** OpenAI-compatible chat completion with tool calling (non-streaming). */
+export async function chatCompletionWithTools(
+  provider: ResolvedLlmProvider,
+  messages: ChatMessage[],
+  tools: OpenAiToolDefinition[] | null,
+): Promise<LlmAssistantResponse> {
+  const body: Record<string, unknown> = {
+    model: provider.model,
+    messages: messages.map(serializeMessage),
+  };
+  if (tools !== null && tools.length > 0) {
+    body.tools = tools;
+    body.tool_choice = "auto";
+  }
+
+  let response: Response;
+  try {
+    response = await fetch(chatUrl(provider.baseUrl), {
+      method: "POST",
+      headers: {
+        Authorization: `Bearer ${provider.apiKey}`,
+        "Content-Type": "application/json",
+      },
+      body: JSON.stringify(body),
+    });
+  } catch (cause) {
+    const message = cause instanceof Error ? cause.message : String(cause);
+    throw new Error(`LLM network error: ${message}`);
+  }
+
+  const responseText = await response.text();
+  if (!response.ok) {
+    throw new Error(`LLM HTTP ${response.status}: ${responseText.slice(0, 2000)}`);
+  }
+
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(responseText) as unknown;
+  } catch (cause) {
+    const message = cause instanceof Error ? cause.message : String(cause);
+    throw new Error(`LLM invalid JSON response: ${message}`);
+  }
+
+  return parseAssistantMessage(parsed);
+}

packages/agent-builtin/src/llm/types.ts

@@ -0,0 +1,29 @@
+export type LlmToolCall = {
+  id: string;
+  name: string;
+  arguments: string;
+};
+
+export type LlmAssistantResponse = {
+  content: string | null;
+  toolCalls: LlmToolCall[] | null;
+};
+
+export type ChatMessage =
+  | { role: "system"; content: string }
+  | { role: "user"; content: string }
+  | {
+      role: "assistant";
+      content: string | null;
+      tool_calls: LlmToolCall[] | null;
+    }
+  | { role: "tool"; tool_call_id: string; content: string };
+
+export type OpenAiToolDefinition = {
+  type: "function";
+  function: {
+    name: string;
+    description: string;
+    parameters: Record<string, unknown>;
+  };
+};

packages/agent-builtin/src/loop.ts

@@ -0,0 +1,303 @@
+import { createLogger } from "@united-workforce/util";
+import type { ResolvedLlmProvider } from "@united-workforce/util-agent";
+
+import {
+  type ChatMessage,
+  chatCompletionWithTools,
+  type LlmToolCall,
+  type OpenAiToolDefinition,
+} from "./llm/index.js";
+import { appendSessionTurn } from "./session.js";
+import {
+  builtinToolsToOpenAi,
+  executeBuiltinTool,
+  getBuiltinTools,
+  type ToolContext,
+} from "./tools/index.js";
+import type { BuiltinToolCall, BuiltinTurnPayload } from "./types.js";
+
+const log = createLogger({ sink: { kind: "stderr" } });
+
+export const BUILTIN_MAX_TURNS = 30;
+export const BUILTIN_CONTINUE_MAX_TURNS = 5;
+
+export type RunBuiltinLoopOptions = {
+  provider: ResolvedLlmProvider;
+  messages: ChatMessage[];
+  toolCtx: ToolContext;
+  maxTurns: number;
+  storageRoot: string;
+  sessionId: string;
+  /** When true, do not provide tools — force LLM to emit text only. */
+  noTools: boolean;
+};
+
+export type RunBuiltinLoopResult = {
+  finalText: string;
+  messages: ChatMessage[];
+  turnCount: number;
+};
+
+function mapToolCallsForPayload(calls: LlmToolCall[]): BuiltinToolCall[] {
+  return calls.map((call) => ({
+    name: call.name,
+    args: call.arguments,
+  }));
+}
+
+async function appendTurn(
+  storageRoot: string,
+  sessionId: string,
+  payload: BuiltinTurnPayload,
+): Promise<void> {
+  await appendSessionTurn(storageRoot, sessionId, payload);
+}
+
+export async function executeTurnTools(
+  calls: Array<{ id: string; name: string; arguments: string }>,
+  toolCtx: ToolContext,
+  messages: ChatMessage[],
+  storageRoot: string,
+  sessionId: string,
+): Promise<number> {
+  let turnCount = 0;
+  for (const call of calls) {
+    const result = await executeBuiltinTool(call.name, call.arguments, toolCtx);
+    messages.push({ role: "tool", tool_call_id: call.id, content: result });
+    await appendTurn(storageRoot, sessionId, {
+      role: "tool",
+      content: result,
+      toolCalls: null,
+      reasoning: null,
+    });
+    turnCount += 1;
+  }
+  return turnCount;
+}
+
+export type ShouldNudgeOptions = {
+  noTools: boolean;
+  text: string;
+  turn: number;
+  maxTurns: number;
+};
+
+const MAX_NUDGES = 3;
+const DEADLINE_WARNING_TURNS = 3;
+
+export function shouldInjectDeadlineWarning(
+  turn: number,
+  maxTurns: number,
+  alreadyWarned: boolean,
+  noTools: boolean,
+): boolean {
+  const turnsRemaining = maxTurns - turn;
+  return (
+    !noTools && !alreadyWarned && turnsRemaining > 0 && turnsRemaining <= DEADLINE_WARNING_TURNS
+  );
+}
+
+export function shouldProcessToolCalls(toolCalls: LlmToolCall[] | null, noTools: boolean): boolean {
+  return !noTools && toolCalls !== null && toolCalls.length > 0;
+}
+
+export function extractFinalText(messages: ChatMessage[]): string {
+  for (let i = messages.length - 1; i >= 0; i--) {
+    const msg = messages[i];
+    if (
+      msg !== undefined &&
+      msg.role === "assistant" &&
+      msg.content !== null &&
+      msg.content.trim() !== ""
+    ) {
+      return msg.content;
+    }
+  }
+  return "";
+}
+
+function injectDeadlineWarning(messages: ChatMessage[], turnsRemaining: number): void {
+  log("4NRXW6KT", `${turnsRemaining} turns remaining, injecting deadline warning`);
+  messages.push({
+    role: "user",
+    content:
+      `⚠️ You have ${turnsRemaining} turns remaining. ` +
+      "Wrap up your work and output the YAML frontmatter starting with `---`. " +
+      "If you cannot finish in time, output frontmatter with `status: failed` and describe what remains.",
+  });
+}
+
+type HandleTextOnlyTurnResult = {
+  shouldBreak: boolean;
+  finalText: string;
+  turnCount: number;
+  nudgeCount: number;
+  turnAdjustment: number;
+};
+
+async function handleTextOnlyTurn(
+  text: string,
+  messages: ChatMessage[],
+  storageRoot: string,
+  sessionId: string,
+  noTools: boolean,
+  turn: number,
+  maxTurns: number,
+  currentNudgeCount: number,
+): Promise<HandleTextOnlyTurnResult> {
+  await appendTurn(storageRoot, sessionId, {
+    role: "assistant",
+    content: text,
+    toolCalls: null,
+    reasoning: null,
+  });
+  const turnCount = 1;
+  let nudgeCount = currentNudgeCount;
+  let turnAdjustment = 0;
+
+  if (shouldNudge({ noTools, text, turn, maxTurns })) {
+    nudgeCount += 1;
+    log("7FXQM2KN", `text-only turn without frontmatter, nudge ${nudgeCount}/${MAX_NUDGES}`);
+    const nudge =
+      "You stopped calling tools but your response does not start with the required `---` YAML frontmatter. " +
+      "Either continue using tools to complete your work, or output your final response starting with `---`.";
+    messages.push({ role: "user", content: nudge });
+    // Nudge doesn't consume turn budget (up to MAX_NUDGES)
+    if (nudgeCount <= MAX_NUDGES) {
+      turnAdjustment = -1;
+    }
+    return { shouldBreak: false, finalText: "", turnCount, nudgeCount, turnAdjustment };
+  }
+
+  return { shouldBreak: true, finalText: text, turnCount, nudgeCount, turnAdjustment };
+}
+
+async function handleToolCallTurn(
+  content: string,
+  toolCalls: LlmToolCall[],
+  messages: ChatMessage[],
+  storageRoot: string,
+  sessionId: string,
+  toolCtx: ToolContext,
+): Promise<number> {
+  await appendTurn(storageRoot, sessionId, {
+    role: "assistant",
+    content,
+    toolCalls: mapToolCallsForPayload(toolCalls),
+    reasoning: null,
+  });
+  let turnCount = 1;
+
+  // Execute tools
+  turnCount += await executeTurnTools(toolCalls, toolCtx, messages, storageRoot, sessionId);
+
+  return turnCount;
+}
+
+export function shouldNudge({ noTools, text, turn, maxTurns }: ShouldNudgeOptions): boolean {
+  return !noTools && !text.trimStart().startsWith("---") && turn < maxTurns - 1;
+}
+
+type ProcessLoopIterationResult = {
+  shouldBreak: boolean;
+  finalText: string;
+  turnCount: number;
+  nudgeCount: number;
+  turnAdjustment: number;
+};
+
+async function processLoopIteration(
+  options: RunBuiltinLoopOptions,
+  messages: ChatMessage[],
+  openAiTools: OpenAiToolDefinition[],
+  turn: number,
+  nudgeCount: number,
+): Promise<ProcessLoopIterationResult> {
+  const response = await chatCompletionWithTools(
+    options.provider,
+    messages,
+    openAiTools.length > 0 ? openAiTools : null,
+  );
+
+  // When noTools is set, ignore any tool_calls the LLM might still return
+  const effectiveToolCalls = options.noTools ? null : (response.toolCalls ?? null);
+
+  const assistantMessage: ChatMessage = {
+    role: "assistant",
+    content: response.content,
+    tool_calls: effectiveToolCalls,
+  };
+  messages.push(assistantMessage);
+
+  if (!shouldProcessToolCalls(effectiveToolCalls, options.noTools)) {
+    const text = response.content ?? "";
+    const result = await handleTextOnlyTurn(
+      text,
+      messages,
+      options.storageRoot,
+      options.sessionId,
+      options.noTools,
+      turn,
+      options.maxTurns,
+      nudgeCount,
+    );
+    return result;
+  }
+
+  // At this point, effectiveToolCalls is guaranteed to be non-null and non-empty
+  const turnCount = await handleToolCallTurn(
+    response.content ?? "",
+    effectiveToolCalls as LlmToolCall[],
+    messages,
+    options.storageRoot,
+    options.sessionId,
+    options.toolCtx,
+  );
+
+  return {
+    shouldBreak: false,
+    finalText: "",
+    turnCount,
+    nudgeCount,
+    turnAdjustment: 0,
+  };
+}
+
+/** Agent run loop: LLM ↔ tools until no tool_calls or maxTurns. */
+export async function runBuiltinLoop(
+  options: RunBuiltinLoopOptions,
+): Promise<RunBuiltinLoopResult> {
+  const messages = [...options.messages];
+  const openAiTools = options.noTools ? [] : builtinToolsToOpenAi(getBuiltinTools());
+  let finalText = "";
+  let turnCount = 0;
+  let nudgeCount = 0;
+  let deadlineWarned = false;
+
+  for (let turn = 0; turn < options.maxTurns; turn++) {
+    log("8K2M4N7P", `builtin loop turn ${turn + 1}/${options.maxTurns}`);
+
+    // Warn agent when approaching turn limit
+    if (shouldInjectDeadlineWarning(turn, options.maxTurns, deadlineWarned, options.noTools)) {
+      deadlineWarned = true;
+      const turnsRemaining = options.maxTurns - turn;
+      injectDeadlineWarning(messages, turnsRemaining);
+    }
+
+    const result = await processLoopIteration(options, messages, openAiTools, turn, nudgeCount);
+    turnCount += result.turnCount;
+    nudgeCount = result.nudgeCount;
+    turn += result.turnAdjustment;
+
+    if (result.shouldBreak) {
+      finalText = result.finalText;
+      break;
+    }
+  }
+
+  if (finalText === "") {
+    finalText = extractFinalText(messages);
+  }
+
+  return { finalText, messages, turnCount };
+}

packages/agent-builtin/src/prompt.ts

@@ -0,0 +1,115 @@
+import { type AgentContext, buildRolePrompt } from "@united-workforce/util-agent";
+
+import type { ChatMessage } from "./llm/index.js";
+
+type StepContext = AgentContext["steps"][number];
+
+function formatStep(step: StepContext, stepNumber: number): string {
+  return [
+    `### Step ${stepNumber}: ${step.role}`,
+    `Output: ${JSON.stringify(step.output)}`,
+    `Agent: ${step.agent}`,
+  ].join("\n");
+}
+
+function buildStepsSummary(steps: StepContext[], fromIndex: number, toIndex: number): string {
+  if (fromIndex >= toIndex) {
+    return "";
+  }
+
+  const lines: string[] = ["## What Happened Since Your Last Turn"];
+  for (let i = fromIndex; i < toIndex; i++) {
+    const step = steps[i];
+    if (step === undefined) {
+      continue;
+    }
+    lines.push("");
+    lines.push(formatStep(step, i + 1));
+  }
+  return lines.join("\n");
+}
+
+function buildUserTurnContent(edgePrompt: string, summary: string): string {
+  const parts: string[] = [];
+  if (edgePrompt !== "") {
+    parts.push(edgePrompt);
+  }
+  if (summary !== "") {
+    if (parts.length > 0) {
+      parts.push("");
+    }
+    parts.push(summary);
+  }
+  return parts.join("\n");
+}
+
+/**
+ * Reconstruct multi-turn chat messages from thread history for cache-friendly session resume.
+ *
+ * - system: role prompt + output format (stable prefix)
+ * - For each prior visit of this role: user (edgePrompt + inter-step summary) + assistant (output JSON)
+ * - Final user: current edgePrompt + summary since last visit of this role
+ */
+export function buildBuiltinMessages(ctx: AgentContext): ChatMessage[] {
+  const roleDef = ctx.workflow.roles[ctx.role];
+  const rolePrompt = roleDef !== undefined ? buildRolePrompt(roleDef) : "";
+  const systemParts: string[] = [];
+  if (ctx.outputFormatInstruction !== "") {
+    systemParts.push(ctx.outputFormatInstruction, "");
+  }
+  systemParts.push(rolePrompt);
+
+  systemParts.push(
+    "",
+    "## Workflow",
+    "",
+    `Your working directory is: ${process.cwd()}`,
+    "",
+    "You have tools available (read_file, write_file, run_command). " +
+      "Use them to complete your task — read files, run commands, make changes as needed. " +
+      "Your task is described in the user message below — do NOT use uwf or workflow CLI commands to discover your task. " +
+      "When you are done, output your final response with the YAML frontmatter block as specified above. " +
+      "Do NOT output the frontmatter until you have completed all necessary work. " +
+      "If you are running low on turns and cannot finish, output the frontmatter with `status: failed` and explain what remains in the body. " +
+      "CRITICAL: Your final output MUST start with the `---` fence on the very first line — " +
+      "no preamble text, no explanation before it. The parser requires `---` at position 0.",
+  );
+
+  const messages: ChatMessage[] = [{ role: "system", content: systemParts.join("\n") }];
+
+  const roleVisitIndices: number[] = [];
+  for (let i = 0; i < ctx.steps.length; i++) {
+    const step = ctx.steps[i];
+    if (step !== undefined && step.role === ctx.role) {
+      roleVisitIndices.push(i);
+    }
+  }
+
+  let prevVisitIndex = -1;
+  for (const visitIndex of roleVisitIndices) {
+    const visitStep = ctx.steps[visitIndex];
+    if (visitStep === undefined) {
+      continue;
+    }
+
+    const summary = buildStepsSummary(ctx.steps, prevVisitIndex + 1, visitIndex);
+    messages.push({
+      role: "user",
+      content: buildUserTurnContent(visitStep.edgePrompt, summary),
+    });
+    messages.push({
+      role: "assistant",
+      content: JSON.stringify(visitStep.output),
+      tool_calls: null,
+    });
+    prevVisitIndex = visitIndex;
+  }
+
+  const finalSummary = buildStepsSummary(ctx.steps, prevVisitIndex + 1, ctx.steps.length);
+  messages.push({
+    role: "user",
+    content: buildUserTurnContent(ctx.edgePrompt, finalSummary),
+  });
+
+  return messages;
+}

packages/agent-builtin/src/schemas.ts

@@ -0,0 +1,45 @@
+import type { JSONSchema } from "@ocas/core";
+
+const BUILTIN_TOOL_CALL_SCHEMA: JSONSchema = {
+  type: "object",
+  required: ["name", "args"],
+  properties: {
+    name: { type: "string" },
+    args: { type: "string" },
+  },
+  additionalProperties: false,
+};
+
+export const BUILTIN_TURN_SCHEMA: JSONSchema = {
+  title: "builtin-turn",
+  type: "object",
+  required: ["role", "content"],
+  properties: {
+    role: { type: "string", enum: ["assistant", "tool"] },
+    content: { type: "string" },
+    toolCalls: {
+      anyOf: [{ type: "array", items: BUILTIN_TOOL_CALL_SCHEMA }, { type: "null" }],
+    },
+    reasoning: {
+      anyOf: [{ type: "string" }, { type: "null" }],
+    },
+  },
+  additionalProperties: false,
+};
+
+export const BUILTIN_DETAIL_SCHEMA: JSONSchema = {
+  title: "builtin-detail",
+  type: "object",
+  required: ["sessionId", "model", "duration", "turnCount", "turns"],
+  properties: {
+    sessionId: { type: "string" },
+    model: { type: "string" },
+    duration: { type: "integer" },
+    turnCount: { type: "integer" },
+    turns: {
+      type: "array",
+      items: { type: "string", format: "ocas_ref" },
+    },
+  },
+  additionalProperties: false,
+};

packages/agent-builtin/src/session.ts

@@ -0,0 +1,59 @@
+import { appendFile, mkdir, readFile, rm } from "node:fs/promises";
+import { join } from "node:path";
+
+import { createLogger } from "@united-workforce/util";
+
+import type { BuiltinTurnPayload } from "./types.js";
+
+const log = createLogger({ sink: { kind: "stderr" } });
+
+function sessionsDir(storageRoot: string): string {
+  return join(storageRoot, "sessions");
+}
+
+function sessionFile(storageRoot: string, sessionId: string): string {
+  return join(sessionsDir(storageRoot), `${sessionId}.jsonl`);
+}
+
+/** Ensure sessions directory exists. */
+export async function initSessionDir(storageRoot: string): Promise<void> {
+  await mkdir(sessionsDir(storageRoot), { recursive: true });
+}
+
+/** Append a turn to the session jsonl file. */
+export async function appendSessionTurn(
+  storageRoot: string,
+  sessionId: string,
+  turn: BuiltinTurnPayload,
+): Promise<void> {
+  const line = `${JSON.stringify(turn)}\n`;
+  await appendFile(sessionFile(storageRoot, sessionId), line, "utf-8");
+  log("3XQVN8KR", `session ${sessionId} appended ${turn.role} turn`);
+}
+
+/** Read all turns from session jsonl. Returns empty array if file does not exist. */
+export async function readSessionTurns(
+  storageRoot: string,
+  sessionId: string,
+): Promise<BuiltinTurnPayload[]> {
+  try {
+    const content = await readFile(sessionFile(storageRoot, sessionId), "utf-8");
+    const lines = content
+      .trim()
+      .split("\n")
+      .filter((l) => l.length > 0);
+    return lines.map((l) => JSON.parse(l) as BuiltinTurnPayload);
+  } catch {
+    return [];
+  }
+}
+
+/** Remove session jsonl file (called after detail is persisted to step CAS). */
+export async function removeSession(storageRoot: string, sessionId: string): Promise<void> {
+  try {
+    await rm(sessionFile(storageRoot, sessionId));
+    log("7FWDP2MJ", `session ${sessionId} removed`);
+  } catch {
+    // already gone — fine
+  }
+}

packages/agent-builtin/src/tools/index.ts

@@ -0,0 +1,44 @@
+import type { OpenAiToolDefinition } from "../llm/index.js";
+
+import { readFileTool } from "./read-file.js";
+import { runCommandTool } from "./run-command.js";
+import type { BuiltinTool, ToolContext } from "./types.js";
+import { writeFileTool } from "./write-file.js";
+
+export { resolvePath } from "./path.js";
+export type { BuiltinTool, ToolContext } from "./types.js";
+
+const BUILTIN_TOOLS: BuiltinTool[] = [readFileTool, writeFileTool, runCommandTool];
+
+export function getBuiltinTools(): readonly BuiltinTool[] {
+  return BUILTIN_TOOLS;
+}
+
+export function builtinToolsToOpenAi(tools: readonly BuiltinTool[]): OpenAiToolDefinition[] {
+  return tools.map((tool) => ({
+    type: "function",
+    function: {
+      name: tool.name,
+      description: tool.description,
+      parameters: tool.parameters as Record<string, unknown>,
+    },
+  }));
+}
+
+export async function executeBuiltinTool(
+  name: string,
+  argsJson: string,
+  ctx: ToolContext,
+): Promise<string> {
+  const tool = BUILTIN_TOOLS.find((t) => t.name === name);
+  if (tool === undefined) {
+    return `Error: unknown tool ${name}`;
+  }
+  let args: unknown;
+  try {
+    args = JSON.parse(argsJson) as unknown;
+  } catch {
+    return "Error: tool arguments must be valid JSON";
+  }
+  return tool.execute(args, ctx);
+}

packages/agent-builtin/src/tools/path.ts

@@ -0,0 +1,6 @@
+import { resolve } from "node:path";
+
+/** Resolve a path relative to the working directory. */
+export function resolvePath(cwd: string, inputPath: string): string {
+  return resolve(cwd, inputPath);
+}

packages/agent-builtin/src/tools/read-file.ts

@@ -0,0 +1,41 @@
+import { readFile, stat } from "node:fs/promises";
+import { resolvePath } from "./path.js";
+import type { BuiltinTool } from "./types.js";
+
+const MAX_READ_BYTES = 512 * 1024;
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null && !Array.isArray(value);
+}
+
+export const readFileTool: BuiltinTool = {
+  name: "read_file",
+  description: "Read a UTF-8 text file from the workspace.",
+  parameters: {
+    type: "object",
+    required: ["path"],
+    properties: {
+      path: { type: "string", description: "Relative or absolute path within the workspace." },
+    },
+    additionalProperties: false,
+  },
+  execute: async (args, ctx) => {
+    if (!isRecord(args) || typeof args.path !== "string") {
+      return "Error: path must be a string";
+    }
+    const resolved = resolvePath(ctx.cwd, args.path);
+    try {
+      const info = await stat(resolved);
+      if (!info.isFile()) {
+        return "Error: not a file";
+      }
+      if (info.size > MAX_READ_BYTES) {
+        return `Error: file exceeds ${MAX_READ_BYTES} byte limit`;
+      }
+      return await readFile(resolved, "utf8");
+    } catch (cause) {
+      const message = cause instanceof Error ? cause.message : String(cause);
+      return `Error: ${message}`;
+    }
+  },
+};

packages/agent-builtin/src/tools/run-command.ts

@@ -0,0 +1,95 @@
+import { spawn } from "node:child_process";
+import { resolvePath } from "./path.js";
+import type { BuiltinTool } from "./types.js";
+
+const COMMAND_TIMEOUT_MS = 60_000;
+const MAX_OUTPUT_CHARS = 32_000;
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null && !Array.isArray(value);
+}
+
+function truncate(text: string, maxChars: number): string {
+  if (text.length <= maxChars) {
+    return text;
+  }
+  return `${text.slice(0, maxChars)}\n...(truncated)`;
+}
+
+function runShell(
+  command: string,
+  cwd: string,
+): Promise<{ stdout: string; stderr: string; code: number }> {
+  return new Promise((resolve, reject) => {
+    const child = spawn(command, {
+      cwd,
+      env: process.env,
+      shell: true,
+      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();
+    });
+
+    const timer = setTimeout(() => {
+      child.kill("SIGTERM");
+    }, COMMAND_TIMEOUT_MS);
+
+    child.on("error", (cause) => {
+      clearTimeout(timer);
+      const message = cause instanceof Error ? cause.message : String(cause);
+      reject(new Error(message));
+    });
+
+    child.on("close", (code) => {
+      clearTimeout(timer);
+      resolve({ stdout, stderr, code: code ?? 1 });
+    });
+  });
+}
+
+export const runCommandTool: BuiltinTool = {
+  name: "run_command",
+  description: "Run a shell command. Output is truncated to 32KB.",
+  parameters: {
+    type: "object",
+    required: ["command"],
+    properties: {
+      command: { type: "string", description: "Shell command to execute." },
+      cwd: {
+        type: "string",
+        description: "Optional working directory relative to workspace root.",
+      },
+    },
+    additionalProperties: false,
+  },
+  execute: async (args, ctx) => {
+    if (!isRecord(args) || typeof args.command !== "string") {
+      return "Error: command must be a string";
+    }
+    let workDir = ctx.cwd;
+    if (args.cwd !== undefined && args.cwd !== null) {
+      if (typeof args.cwd !== "string") {
+        return "Error: cwd must be a string";
+      }
+      workDir = resolvePath(ctx.cwd, args.cwd);
+    }
+    try {
+      const { stdout, stderr, code } = await runShell(args.command, workDir);
+      const out = truncate(
+        `exit_code: ${code}\n--- stdout ---\n${stdout}\n--- stderr ---\n${stderr}`,
+        MAX_OUTPUT_CHARS,
+      );
+      return out;
+    } catch (cause) {
+      const message = cause instanceof Error ? cause.message : String(cause);
+      return `Error: ${message}`;
+    }
+  },
+};

packages/agent-builtin/src/tools/types.ts

@@ -0,0 +1,13 @@
+import type { JSONSchema } from "@ocas/core";
+
+export type ToolContext = {
+  cwd: string;
+  storageRoot: string;
+};
+
+export type BuiltinTool = {
+  name: string;
+  description: string;
+  parameters: JSONSchema;
+  execute: (args: unknown, ctx: ToolContext) => Promise<string>;
+};

packages/agent-builtin/src/tools/write-file.ts

@@ -0,0 +1,36 @@
+import { mkdir, writeFile } from "node:fs/promises";
+import { dirname } from "node:path";
+import { resolvePath } from "./path.js";
+import type { BuiltinTool } from "./types.js";
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null && !Array.isArray(value);
+}
+
+export const writeFileTool: BuiltinTool = {
+  name: "write_file",
+  description: "Write UTF-8 text to a file in the workspace (creates parent directories).",
+  parameters: {
+    type: "object",
+    required: ["path", "content"],
+    properties: {
+      path: { type: "string", description: "Relative or absolute path within the workspace." },
+      content: { type: "string", description: "File contents to write." },
+    },
+    additionalProperties: false,
+  },
+  execute: async (args, ctx) => {
+    if (!isRecord(args) || typeof args.path !== "string" || typeof args.content !== "string") {
+      return "Error: path and content must be strings";
+    }
+    const resolved = resolvePath(ctx.cwd, args.path);
+    try {
+      await mkdir(dirname(resolved), { recursive: true });
+      await writeFile(resolved, args.content, "utf8");
+      return `Wrote ${args.content.length} bytes to ${args.path}`;
+    } catch (cause) {
+      const message = cause instanceof Error ? cause.message : String(cause);
+      return `Error: ${message}`;
+    }
+  },
+};

packages/agent-builtin/src/types.ts

@@ -0,0 +1,49 @@
+import type { ChatMessage } from "./llm/index.js";
+
+export type BuiltinToolCallRecord = {
+  id: string;
+  name: string;
+  args: string;
+};
+
+export type BuiltinToolResultRecord = {
+  toolCallId: string;
+  name: string;
+  content: string;
+};
+
+export type BuiltinLoopTurn = {
+  assistantContent: string | null;
+  toolCalls: BuiltinToolCallRecord[] | null;
+  toolResults: BuiltinToolResultRecord[] | null;
+};
+
+export type BuiltinSessionState = {
+  sessionId: string;
+  model: string;
+  startedAtMs: number;
+  messages: ChatMessage[];
+  turns: BuiltinLoopTurn[];
+};
+
+export type BuiltinTurnRole = "assistant" | "tool";
+
+export type BuiltinToolCall = {
+  name: string;
+  args: string;
+};
+
+export type BuiltinTurnPayload = {
+  role: BuiltinTurnRole;
+  content: string;
+  toolCalls: BuiltinToolCall[] | null;
+  reasoning: string | null;
+};
+
+export type BuiltinDetailPayload = {
+  sessionId: string;
+  model: string;
+  duration: number;
+  turnCount: number;
+  turns: string[];
+};

packages/agent-builtin/tsconfig.json

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