feat(cli): add live command for real-time thread monitoring (#37 Phase 1)

- Add cmd-live.ts: tail .data.jsonl with formatted output
- Display role steps with timestamp, role name, truncated content, meta
- fs.watch for running threads, auto-exit on completion
- Write WorkflowResult to .data.jsonl in worker.ts for completion detection
- Add live.test.ts with JSONL fixtures

Testing: #49

packages/cli-workflow/__tests__/fixtures/live/logs/C9NMV6V2TQT81/01LIVECMPLT01DDDDDDDDDDDDG.data.jsonl

@@ -0,0 +1,4 @@
+{"name":"demo-live","hash":"C9NMV6V2TQT81","threadId":"01LIVECMPLT01DDDDDDDDDDDDG","parameters":{"prompt":"hello","options":{"maxRounds":5,"depth":0}},"timestamp":1714963200000}
+{"role":"planner","content":"alpha\nbeta\ngamma\nLINE4\nLINE5\nLINE6\nLINE7\nLINE8\nLINE9\nLINE10\nLINE11","meta":{"phase":"plan","flags":[1,2]},"refs":[],"timestamp":1714963201000}
+{"role":"coder","content":"patch","meta":{},"refs":[],"timestamp":1714963202000}
+{"returnCode":0,"summary":"fixture completed"}

packages/cli-workflow/__tests__/fixtures/live/logs/C9NMV6V2TQT81/01LIVEINFLY01DDDDDDDDDDDDG.data.jsonl

@@ -0,0 +1,2 @@
+{"name":"demo-live","hash":"C9NMV6V2TQT81","threadId":"01LIVEINFLY01DDDDDDDDDDDDG","parameters":{"prompt":"hello","options":{"maxRounds":5,"depth":0}},"timestamp":1714963200000}
+{"role":"planner","content":"still running","meta":{"x":1},"refs":[],"timestamp":1714963201000}

packages/cli-workflow/__tests__/fork-cli.test.ts

@@ -111,7 +111,7 @@ describe("cli fork", () => {
     const sourceData = join(storageRoot, "logs", hash, `${sourceId}.data.jsonl`);
     const sourceRunning = join(storageRoot, "logs", hash, `${sourceId}.running`);
     await waitUntilRunningAbsent(sourceRunning);
-    await waitUntilMinDataLines(sourceData, 4);
+    await waitUntilMinDataLines(sourceData, 5);
 
     const forked = await cmdFork(storageRoot, sourceId, "planner");
     expect(forked.ok).toBe(true);
@@ -122,14 +122,14 @@ describe("cli fork", () => {
     const newData = join(storageRoot, "logs", hash, `${newId}.data.jsonl`);
     const newRunning = join(storageRoot, "logs", hash, `${newId}.running`);
     await waitUntilRunningAbsent(newRunning);
-    await waitUntilMinDataLines(newData, 4);
+    await waitUntilMinDataLines(newData, 5);
 
     const text = await readFile(newData, "utf8");
     const lines = text
       .trim()
       .split("\n")
       .filter((l) => l !== "");
-    expect(lines.length).toBe(4);
+    expect(lines.length).toBe(5);
     const start = JSON.parse(lines[0] ?? "{}") as Record<string, unknown>;
     expect(start.threadId).toBe(newId);
     expect(start.forkFrom).toEqual({ threadId: sourceId });
@@ -162,7 +162,7 @@ describe("cli fork", () => {
     const sourceData = join(storageRoot, "logs", hash, `${sourceId}.data.jsonl`);
     const sourceRunning = join(storageRoot, "logs", hash, `${sourceId}.running`);
     await waitUntilRunningAbsent(sourceRunning);
-    await waitUntilMinDataLines(sourceData, 4);
+    await waitUntilMinDataLines(sourceData, 5);
 
     const forked = await cmdFork(storageRoot, sourceId, null);
     expect(forked.ok).toBe(true);
@@ -173,14 +173,14 @@ describe("cli fork", () => {
     const newData = join(storageRoot, "logs", hash, `${newId}.data.jsonl`);
     const newRunning = join(storageRoot, "logs", hash, `${newId}.running`);
     await waitUntilRunningAbsent(newRunning);
-    await waitUntilMinDataLines(newData, 4);
+    await waitUntilMinDataLines(newData, 5);
 
     const text = await readFile(newData, "utf8");
     const lines = text
       .trim()
       .split("\n")
       .filter((l) => l !== "");
-    expect(lines.length).toBe(4);
+    expect(lines.length).toBe(5);
 
     const replayCoder = JSON.parse(lines[2] ?? "{}") as Record<string, unknown>;
     expect(replayCoder.role).toBe("coder");
@@ -213,7 +213,7 @@ describe("cli fork", () => {
     const sourceData = join(storageRoot, "logs", added.value.hash, `${sourceId}.data.jsonl`);
     const sourceRunning = join(storageRoot, "logs", added.value.hash, `${sourceId}.running`);
     await waitUntilRunningAbsent(sourceRunning);
-    await waitUntilMinDataLines(sourceData, 4);
+    await waitUntilMinDataLines(sourceData, 5);
 
     const bad = await cmdFork(storageRoot, sourceId, "ghost-role");
     expect(bad.ok).toBe(false);

packages/cli-workflow/__tests__/live.test.ts

@@ -0,0 +1,153 @@
+import { afterEach, beforeEach, describe, expect, test } from "bun:test";
+import { spawn, spawnSync } from "node:child_process";
+import { cp, mkdir, mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { fileURLToPath } from "node:url";
+
+import {
+  formatLiveTimeLabel,
+  LIVE_CONTENT_MAX_LINES,
+  type LiveRoleRow,
+  renderLiveRoleStepLines,
+} from "../src/cmd-live.js";
+
+const cliEntryPath = fileURLToPath(new URL("../src/cli.ts", import.meta.url));
+const fixtureRoot = fileURLToPath(new URL("./fixtures/live", import.meta.url));
+
+describe("live helpers", () => {
+  test("formatLiveTimeLabel pads HH:MM:SS", () => {
+    const label = formatLiveTimeLabel(new Date("2024-06-01T09:08:07.000Z").getTime());
+    expect(label).toMatch(/^\d{2}:\d{2}:\d{2}$/);
+  });
+
+  test("renderLiveRoleStepLines truncates content to LIVE_CONTENT_MAX_LINES", () => {
+    const lines = Array.from({ length: LIVE_CONTENT_MAX_LINES + 3 }, (_, i) => `L${i + 1}`);
+    const row: LiveRoleRow = {
+      role: "r",
+      content: lines.join("\n"),
+      meta: { k: "v" },
+      timestamp: 0,
+    };
+    const out = renderLiveRoleStepLines(row, "r");
+    const body = out.filter((l) => l.startsWith("  L"));
+    expect(body.length).toBe(LIVE_CONTENT_MAX_LINES);
+    expect(out.some((l) => l.includes("more line"))).toBe(true);
+    expect(out.some((l) => l.startsWith("  meta: "))).toBe(true);
+  });
+});
+
+describe("live CLI", () => {
+  let prevEnv: string | undefined;
+  let storageRoot: string;
+
+  beforeEach(async () => {
+    prevEnv = process.env.UNCAGED_WORKFLOW_STORAGE_ROOT;
+    storageRoot = await mkdtemp(join(tmpdir(), "uncaged-wf-live-"));
+    process.env.UNCAGED_WORKFLOW_STORAGE_ROOT = storageRoot;
+    await mkdir(join(storageRoot, "logs", "C9NMV6V2TQT81"), { recursive: true });
+    await cp(
+      join(fixtureRoot, "logs", "C9NMV6V2TQT81", "01LIVECMPLT01DDDDDDDDDDDDG.data.jsonl"),
+      join(storageRoot, "logs", "C9NMV6V2TQT81", "01LIVECMPLT01DDDDDDDDDDDDG.data.jsonl"),
+    );
+    await cp(
+      join(fixtureRoot, "logs", "C9NMV6V2TQT81", "01LIVEINFLY01DDDDDDDDDDDDG.data.jsonl"),
+      join(storageRoot, "logs", "C9NMV6V2TQT81", "01LIVEINFLY01DDDDDDDDDDDDG.data.jsonl"),
+    );
+  });
+
+  afterEach(async () => {
+    if (prevEnv === undefined) {
+      delete process.env.UNCAGED_WORKFLOW_STORAGE_ROOT;
+    } else {
+      process.env.UNCAGED_WORKFLOW_STORAGE_ROOT = prevEnv;
+    }
+    await rm(storageRoot, { recursive: true, force: true });
+  });
+
+  test("prints role steps and summary for a completed thread", async () => {
+    const env = { ...process.env, UNCAGED_WORKFLOW_STORAGE_ROOT: storageRoot };
+    const proc = spawn(process.execPath, [cliEntryPath, "live", "01LIVECMPLT01DDDDDDDDDDDDG"], {
+      env,
+      stdio: ["ignore", "pipe", "pipe"],
+    });
+    const stdout = await new Promise<string>((resolve, reject) => {
+      let buf = "";
+      proc.stdout?.on("data", (c: Buffer) => {
+        buf += c.toString("utf8");
+      });
+      proc.stderr?.on("data", (c: Buffer) => {
+        buf += c.toString("utf8");
+      });
+      proc.on("error", reject);
+      proc.on("exit", (code: number | null) => {
+        if (code === 0) {
+          resolve(buf);
+        } else {
+          reject(new Error(`exit ${code}: ${buf}`));
+        }
+      });
+    });
+
+    expect(stdout).toContain("planner");
+    expect(stdout).toContain("coder");
+    expect(stdout).toContain("meta:");
+    expect(stdout).toContain('"phase":"plan"');
+    expect(stdout).toContain("LINE10");
+    expect(stdout).not.toContain("LINE11");
+    expect(stdout).toContain("more line");
+    expect(stdout).toContain("completed: returnCode=0");
+    expect(stdout).toContain("fixture completed");
+  });
+
+  test("unknown thread id exits 1", () => {
+    const env = { ...process.env, UNCAGED_WORKFLOW_STORAGE_ROOT: storageRoot };
+    const r = spawnSync(process.execPath, [cliEntryPath, "live", "01UNKNOWNXXXXXXXXXXXXXXXXX"], {
+      env,
+      encoding: "utf8",
+    });
+    expect(r.status).toBe(1);
+    expect(String(r.stderr ?? "")).toContain("thread not found");
+  });
+
+  test("follows file until WorkflowResult is appended", async () => {
+    const env = { ...process.env, UNCAGED_WORKFLOW_STORAGE_ROOT: storageRoot };
+    const dataPath = join(
+      storageRoot,
+      "logs",
+      "C9NMV6V2TQT81",
+      "01LIVEINFLY01DDDDDDDDDDDDG.data.jsonl",
+    );
+
+    const proc = spawn(process.execPath, [cliEntryPath, "live", "01LIVEINFLY01DDDDDDDDDDDDG"], {
+      env,
+      stdio: ["ignore", "pipe", "pipe"],
+    });
+
+    await new Promise((r) => setTimeout(r, 120));
+    const prior = await readFile(dataPath, "utf8");
+    await writeFile(dataPath, `${prior}{"returnCode":0,"summary":"caught up"}\n`, "utf8");
+
+    const stdout = await new Promise<string>((resolve, reject) => {
+      let buf = "";
+      proc.stdout?.on("data", (c: Buffer) => {
+        buf += c.toString("utf8");
+      });
+      proc.stderr?.on("data", (c: Buffer) => {
+        buf += c.toString("utf8");
+      });
+      proc.on("error", reject);
+      proc.on("exit", (code: number | null) => {
+        if (code === 0) {
+          resolve(buf);
+        } else {
+          reject(new Error(`exit ${code}: ${buf}`));
+        }
+      });
+    });
+
+    expect(stdout).toContain("planner");
+    expect(stdout).toContain("completed: returnCode=0");
+    expect(stdout).toContain("caught up");
+  });
+});

packages/cli-workflow/__tests__/thread-cli.test.ts

@@ -323,7 +323,7 @@ describe("cli thread commands", () => {
       .trim()
       .split("\n")
       .filter((l) => l !== "");
-    expect(lines.length).toBe(2);
+    expect(lines.length).toBe(3);
 
     const runningPath = join(dirname(dataPath), `${threadId}.running`);
     expect(await pathExists(runningPath)).toBe(false);
@@ -362,8 +362,8 @@ describe("cli thread commands", () => {
     const resumed = await cmdResume(storageRoot, threadId);
     expect(resumed.ok).toBe(true);
 
-    await waitUntilMinDataLines(dataPath, 3, 120);
+    await waitUntilMinDataLines(dataPath, 4, 120);
-    expect(await countDataJsonlLines(dataPath)).toBe(3);
+    expect(await countDataJsonlLines(dataPath)).toBe(4);
 
     const runningPath = join(dirname(dataPath), `${threadId}.running`);
     await waitUntilRunningFileAbsent(runningPath, 100);

packages/cli-workflow/src/cli-dispatch.ts

@@ -7,6 +7,7 @@ import { cmdHistory } from "./cmd-history.js";
 import { cmdInitTemplate, cmdInitWorkspace } from "./cmd-init.js";
 import { cmdKill } from "./cmd-kill.js";
 import { cmdList, formatListLines } from "./cmd-list.js";
+import { cmdLive } from "./cmd-live.js";
 import { cmdPause } from "./cmd-pause.js";
 import { cmdPs } from "./cmd-ps.js";
 import { cmdRemove } from "./cmd-remove.js";
@@ -28,6 +29,7 @@ export function formatCliUsage(): string {
     "  uncaged-workflow run <name> [--prompt <text>] [--max-rounds N]",
     "  uncaged-workflow ps",
     "  uncaged-workflow kill <thread-id>",
+    "  uncaged-workflow live <thread-id>",
     "  uncaged-workflow history <name>",
     "  uncaged-workflow rollback <name> [hash]",
     "  uncaged-workflow pause <thread-id>",
@@ -190,6 +192,15 @@ async function dispatchKill(storageRoot: string, argv: string[]): Promise<number
   return 0;
 }
 
+async function dispatchLive(storageRoot: string, argv: string[]): Promise<number> {
+  const threadId = argv[0];
+  if (threadId === undefined || argv.length > 1) {
+    printCliError(`${usage()}\n\nerror: live requires <thread-id>`);
+    return 1;
+  }
+  return cmdLive(storageRoot, threadId);
+}
+
 async function dispatchHistory(storageRoot: string, argv: string[]): Promise<number> {
   const name = argv[0];
   if (name === undefined || argv.length > 1) {
@@ -435,6 +446,7 @@ const COMMAND_TABLE: Record<string, DispatchFn> = {
   run: dispatchRun,
   ps: dispatchPs,
   kill: dispatchKill,
+  live: dispatchLive,
   history: dispatchHistory,
   rollback: dispatchRollback,
   pause: dispatchPause,

packages/cli-workflow/src/cmd-live.ts

@@ -0,0 +1,254 @@
+import { watch } from "node:fs";
+import { readFile } from "node:fs/promises";
+
+import {
+  tryParseRoleStepRecord,
+  tryParseWorkflowResultRecord,
+  type WorkflowResult,
+} from "@uncaged/workflow";
+
+import { printCliError, printCliLine } from "./cli-output.js";
+import { resolveThreadDataPath } from "./thread-scan.js";
+
+export const LIVE_CONTENT_MAX_LINES = 10;
+
+export type LiveRoleRow = {
+  role: string;
+  content: string;
+  meta: Record<string, unknown>;
+  timestamp: number;
+};
+
+export function formatLiveTimeLabel(timestampMs: number): string {
+  const d = new Date(timestampMs);
+  const hh = String(d.getHours()).padStart(2, "0");
+  const mm = String(d.getMinutes()).padStart(2, "0");
+  const ss = String(d.getSeconds()).padStart(2, "0");
+  return `${hh}:${mm}:${ss}`;
+}
+
+function shouldUseColor(): boolean {
+  return process.stdout.isTTY === true && process.env.NO_COLOR === undefined;
+}
+
+function highlightLiveRole(name: string): string {
+  if (!shouldUseColor()) {
+    return name;
+  }
+  return `\x1b[1m\x1b[36m${name}\x1b[0m`;
+}
+
+export function renderLiveRoleStepLines(row: LiveRoleRow, roleDisplay: string): string[] {
+  const header = `[${formatLiveTimeLabel(row.timestamp)}] ▶ ${roleDisplay}`;
+  const lines: string[] = [header];
+  const parts = row.content.split("\n");
+  const shown = parts.slice(0, LIVE_CONTENT_MAX_LINES);
+  for (const ln of shown) {
+    lines.push(`  ${ln}`);
+  }
+  const omitted = parts.length - shown.length;
+  if (omitted > 0) {
+    lines.push(`  … (${omitted} more line${omitted === 1 ? "" : "s"})`);
+  }
+  lines.push(`  meta: ${JSON.stringify(row.meta)}`);
+  return lines;
+}
+
+function printSummary(result: WorkflowResult): void {
+  printCliLine(`completed: returnCode=${result.returnCode} — ${result.summary}`);
+}
+
+type LiveSessionState = {
+  sawStart: boolean;
+  completed: boolean;
+  carry: string;
+  contentOffset: number;
+};
+
+function handleJsonlLine(
+  rawLine: string,
+  state: LiveSessionState,
+): { parseError: string | null; workflowResult: WorkflowResult | null } {
+  const trimmed = rawLine.trim();
+  if (trimmed === "") {
+    return { parseError: null, workflowResult: null };
+  }
+
+  let rec: unknown;
+  try {
+    rec = JSON.parse(trimmed) as unknown;
+  } catch {
+    return { parseError: "invalid JSON in thread data file", workflowResult: null };
+  }
+  if (rec === null || typeof rec !== "object") {
+    return { parseError: "invalid record in thread data file", workflowResult: null };
+  }
+  const obj = rec as Record<string, unknown>;
+
+  if (!state.sawStart) {
+    state.sawStart = true;
+    return { parseError: null, workflowResult: null };
+  }
+
+  const wf = tryParseWorkflowResultRecord(obj);
+  if (wf !== null) {
+    state.completed = true;
+    return { parseError: null, workflowResult: wf };
+  }
+
+  const roleRow = tryParseRoleStepRecord(obj);
+  if (roleRow === null) {
+    return {
+      parseError: "unrecognized record in thread data (expected role step or result)",
+      workflowResult: null,
+    };
+  }
+
+  const row: LiveRoleRow = {
+    role: roleRow.role,
+    content: roleRow.content,
+    meta: roleRow.meta,
+    timestamp: roleRow.timestamp,
+  };
+  for (const outLine of renderLiveRoleStepLines(row, highlightLiveRole(row.role))) {
+    printCliLine(outLine);
+  }
+  return { parseError: null, workflowResult: null };
+}
+
+async function pumpNewContent(dataPath: string, state: LiveSessionState): Promise<number | null> {
+  let text: string;
+  try {
+    text = await readFile(dataPath, "utf8");
+  } catch {
+    return null;
+  }
+
+  if (text.length < state.contentOffset) {
+    state.contentOffset = 0;
+    state.carry = "";
+  }
+
+  const chunk = text.slice(state.contentOffset);
+  state.contentOffset = text.length;
+  state.carry += chunk;
+
+  const parts = state.carry.split("\n");
+  state.carry = parts.pop() ?? "";
+
+  for (const line of parts) {
+    const { parseError, workflowResult } = handleJsonlLine(line, state);
+    if (parseError !== null) {
+      printCliError(parseError);
+      return 1;
+    }
+    if (workflowResult !== null) {
+      printSummary(workflowResult);
+      return 0;
+    }
+  }
+
+  return null;
+}
+
+function watchLiveFile(params: {
+  dataPath: string;
+  state: LiveSessionState;
+  signal: AbortSignal;
+}): Promise<number> {
+  const { dataPath, state, signal } = params;
+
+  return new Promise((resolve, reject) => {
+    let settled = false;
+    const finish = (code: number): void => {
+      if (settled) {
+        return;
+      }
+      settled = true;
+      resolve(code);
+    };
+
+    /** Serialize reads — `fs.watch` may emit faster than `readFile` completes. */
+    let pumpChain: Promise<void> = Promise.resolve();
+
+    const watcher = watch(dataPath, (eventType) => {
+      if (eventType === "rename") {
+        return;
+      }
+      schedulePump();
+    });
+
+    watcher.on("error", (err: Error) => {
+      watcher.close();
+      reject(err);
+    });
+
+    const onAbort = (): void => {
+      watcher.close();
+      finish(0);
+    };
+    signal.addEventListener("abort", onAbort, { once: true });
+
+    async function drainQueuedPump(): Promise<void> {
+      if (settled) {
+        return;
+      }
+      try {
+        const code = await pumpNewContent(dataPath, state);
+        if (code !== null) {
+          watcher.close();
+          finish(code);
+        }
+      } catch (e) {
+        watcher.close();
+        reject(e instanceof Error ? e : new Error(String(e)));
+      }
+    }
+
+    function schedulePump(): void {
+      pumpChain = pumpChain.then(() => drainQueuedPump());
+    }
+
+    schedulePump();
+  });
+}
+
+export async function cmdLive(storageRoot: string, threadId: string): Promise<number> {
+  const dataPath = await resolveThreadDataPath(storageRoot, threadId);
+  if (dataPath === null) {
+    printCliError(`thread not found: ${threadId}`);
+    return 1;
+  }
+
+  const state: LiveSessionState = {
+    sawStart: false,
+    completed: false,
+    carry: "",
+    contentOffset: 0,
+  };
+
+  const controller = new AbortController();
+  const onSigInt = (): void => {
+    controller.abort();
+  };
+  process.on("SIGINT", onSigInt);
+
+  try {
+    const first = await pumpNewContent(dataPath, state);
+    if (first !== null) {
+      return first;
+    }
+
+    if (state.completed) {
+      return 0;
+    }
+
+    return await watchLiveFile({ dataPath, state, signal: controller.signal });
+  } catch (e) {
+    const message = e instanceof Error ? e.message : String(e);
+    printCliError(`live: ${message}`);
+    return 1;
+  } finally {
+    process.off("SIGINT", onSigInt);
+  }
+}

packages/workflow/__tests__/fork-thread.test.ts

@@ -87,6 +87,26 @@ describe("fork-thread", () => {
     expect(r.value.runOptions).toEqual({ maxRounds: 5, depth: 0 });
   });
 
+  test("parseThreadDataJsonl ignores trailing WorkflowResult line", () => {
+    const text = `${sampleDataJsonl.trim()}\n{"returnCode":0,"summary":"done"}\n`;
+    const r = parseThreadDataJsonl(text);
+    expect(r.ok).toBe(true);
+    if (!r.ok) {
+      return;
+    }
+    expect(r.value.roleSteps.length).toBe(3);
+    expect(r.value.roleSteps[2]?.role).toBe("reviewer");
+  });
+
+  test("parseThreadDataJsonl errors when WorkflowResult is not last", () => {
+    const text = `{"name":"demo","hash":"H","threadId":"01ZZZZZZZZZZZZZZZZZZZZZZ","parameters":{"prompt":"p","options":{"maxRounds":3}},"timestamp":1}
+{"returnCode":0,"summary":"early"}
+{"role":"planner","content":"x","meta":{},"timestamp":2}
+`;
+    const r = parseThreadDataJsonl(text);
+    expect(r.ok).toBe(false);
+  });
+
   test("parseThreadDataJsonl reads explicit depth from start record", () => {
     const text = `{"name":"demo","hash":"H","threadId":"01ZZZZZZZZZZZZZZZZZZZZZZ","parameters":{"prompt":"p","options":{"maxRounds":3,"depth":2}},"timestamp":1}
 {"role":"planner","contentHash":"HP0000000000000000000099","meta":{},"refs":[],"timestamp":2}

packages/workflow/__tests__/worker.test.ts

@@ -125,7 +125,7 @@ describe("worker process", () => {
           .trim()
           .split("\n")
           .filter((l) => l !== "").length,
-      ).toBe(3);
+      ).toBe(4);
     } finally {
       await rm(root, { recursive: true, force: true });
     }
@@ -187,7 +187,7 @@ describe("worker process", () => {
         .trim()
         .split("\n")
         .filter((l) => l !== "");
-      expect(lines.length).toBe(3);
+      expect(lines.length).toBe(4);
       const start = JSON.parse(lines[0] ?? "{}") as Record<string, unknown>;
       expect(start.forkFrom).toEqual({ threadId: srcId });
       const replay = JSON.parse(lines[1] ?? "{}") as Record<string, unknown>;
@@ -195,6 +195,8 @@ describe("worker process", () => {
       expect(replay.timestamp).toBe(555);
       const coder = JSON.parse(lines[2] ?? "{}") as Record<string, unknown>;
       expect(coder.role).toBe("coder");
+      const done = JSON.parse(lines[3] ?? "{}") as Record<string, unknown>;
+      expect(done.returnCode).toBe(0);
     } finally {
       await rm(root, { recursive: true, force: true });
     }

packages/workflow/src/fork-thread.ts

@@ -1,6 +1,6 @@
 import { normalizeRefsField } from "./refs-field.js";
 import { err, ok, type Result } from "./result.js";
-import type { RoleOutput } from "./types.js";
+import type { RoleOutput, WorkflowResult } from "./types.js";
 
 /** Role steps replayed from `.data.jsonl`, including persisted timestamps. */
 export type ForkHistoricalStep = RoleOutput & { timestamp: number };
@@ -14,33 +14,54 @@ export type ParsedThreadStartRecord = {
   depth: number;
 };
 
-function parseRoleLine(
+/** Recognizes a persisted workflow completion line (no `role`; has numeric `returnCode` and string `summary`). */
-  obj: Record<string, unknown>,
+export function tryParseWorkflowResultRecord(obj: Record<string, unknown>): WorkflowResult | null {
-  lineIndex: number,
+  if (obj.role !== undefined) {
-): Result<ForkHistoricalStep, string> {
+    return null;
+  }
+  const returnCode = obj.returnCode;
+  const summary = obj.summary;
+  if (typeof returnCode !== "number" || typeof summary !== "string") {
+    return null;
+  }
+  return { returnCode, summary };
+}
+
+export function tryParseRoleStepRecord(obj: Record<string, unknown>): ForkHistoricalStep | null {
   const role = obj.role;
   const contentHash = obj.contentHash;
   const meta = obj.meta;
   const timestamp = obj.timestamp;
   if (typeof role !== "string") {
-    return err(`invalid role record at line ${lineIndex}: missing role`);
+    return null;
   }
   if (typeof contentHash !== "string") {
-    return err(`invalid role record at line ${lineIndex}: missing contentHash`);
+    return null;
   }
   if (meta === null || typeof meta !== "object") {
-    return err(`invalid role record at line ${lineIndex}: missing meta`);
+    return null;
   }
   if (typeof timestamp !== "number") {
-    return err(`invalid role record at line ${lineIndex}: missing timestamp`);
+    return null;
   }
-  return ok({
+  return {
     role,
     contentHash,
     meta: meta as Record<string, unknown>,
     refs: normalizeRefsField(obj.refs),
     timestamp,
-  });
+  };
+}
+
+function parseRoleLine(
+  obj: Record<string, unknown>,
+  lineIndex: number,
+): Result<ForkHistoricalStep, string> {
+  const parsed = tryParseRoleStepRecord(obj);
+  if (parsed === null) {
+    return err(`invalid role record at line ${lineIndex}`);
+  }
+  return ok(parsed);
 }
 
 function parseStartRecordLine(firstLine: string): Result<ParsedThreadStartRecord, string> {
@@ -109,7 +130,15 @@ function parseFollowingRoleLines(lines: string[]): Result<ForkHistoricalStep[],
     if (rec === null || typeof rec !== "object") {
       return err(`invalid record at line ${i + 1}`);
     }
-    const parsed = parseRoleLine(rec as Record<string, unknown>, i + 1);
+    const recObj = rec as Record<string, unknown>;
+    const wf = tryParseWorkflowResultRecord(recObj);
+    if (wf !== null) {
+      if (i !== lines.length - 1) {
+        return err("WorkflowResult record must be the final line in `.data.jsonl`");
+      }
+      break;
+    }
+    const parsed = parseRoleLine(recObj, i + 1);
     if (!parsed.ok) {
       return parsed;
     }

packages/workflow/src/index.ts

@@ -25,6 +25,8 @@ export {
   type ParsedThreadStartRecord,
   parseThreadDataJsonl,
   selectForkHistoricalSteps,
+  tryParseRoleStepRecord,
+  tryParseWorkflowResultRecord,
 } from "./fork-thread.js";
 export { type GcResult, garbageCollectCas } from "./gc.js";
 export { stringifyWorkflowDescriptor } from "./generate-descriptor.js";

packages/workflow/src/worker.ts

@@ -1,4 +1,4 @@
-import { mkdir, unlink, writeFile } from "node:fs/promises";
+import { appendFile, mkdir, unlink, writeFile } from "node:fs/promises";
 import { createServer, type Socket } from "node:net";
 import { dirname, join } from "node:path";
 import { importWorkflowBundleModule } from "./bundle-import-env.js";
@@ -11,7 +11,7 @@ import { normalizeRefsField } from "./refs-field.js";
 import { err, ok, type Result } from "./result.js";
 import { getGlobalCasDir } from "./storage-root.js";
 import { createThreadPauseGate, type ThreadPauseGate } from "./thread-pause-gate.js";
-import type { RoleOutput, WorkflowFn } from "./types.js";
+import type { RoleOutput, WorkflowFn, WorkflowResult } from "./types.js";
 
 const bootLog = createLogger({ sink: { kind: "stderr" } });
 
@@ -404,7 +404,7 @@ async function main(): Promise<void> {
         });
       }
 
-      await executeThread(
+      const runResult = await executeThread(
         workflowFn,
         cmd.workflowName,
         { prompt: cmd.prompt, steps: cmd.steps },
@@ -418,9 +418,12 @@ async function main(): Promise<void> {
         io,
         logger,
       );
+      await appendFile(dataJsonlPath, `${JSON.stringify(runResult)}\n`, "utf8");
     } catch (e) {
       const message = e instanceof Error ? e.message : String(e);
       bootLog("Q3MN8YKW", `thread ${threadId} failed: ${message}`);
+      const failure: WorkflowResult = { returnCode: 1, summary: message };
+      await appendFile(dataJsonlPath, `${JSON.stringify(failure)}\n`, "utf8").catch(() => {});
     } finally {
       threads.delete(threadId);
       await unlink(runningPath).catch(() => {});