feat: add live executor observability

src/child-process.test.ts

@@ -1,4 +1,6 @@
 import assert from "node:assert/strict";
+import fs from "node:fs";
+import path from "node:path";
 import { Writable } from "node:stream";
 import { test } from "vitest";
 import { spawnBufferedChild, spawnStreamingChild } from "./child-process.js";
@@ -117,3 +119,134 @@ test("spawnStreamingChild escalates ignored SIGTERM to SIGKILL after the abort g
   assert.equal(child.signal, "SIGKILL");
   assert.match(chunks.join("") + child.stdout, /ready/);
 });
+
+// ---------------------------------------------------------------------------
+// logFilePath tee (real-time observability)
+// ---------------------------------------------------------------------------
+
+test("logFilePath: stdout is readable from the log file before the child exits", async () => {
+  const tmpDir = fs.mkdtempSync("/tmp/agent-workflow-tee-test-");
+  try {
+    const logFile = path.join(tmpDir, "exec.log");
+    const { stream } = collectSink();
+    const script = [
+      "process.stdout.write('pre-delay\\n');",
+      "setTimeout(() => { process.stdout.write('post-delay\\n'); }, 200);",
+    ].join("");
+
+    const childPromise = spawnStreamingChild(process.execPath, ["-e", script], {
+      stdoutSink: stream,
+      stderrSink: stream,
+      logFilePath: logFile,
+    });
+
+    // Before the child finishes, the log file should already have 'pre-delay'
+    await new Promise<void>((resolve, reject) => {
+      const check = () => {
+        try {
+          if (fs.existsSync(logFile) && fs.readFileSync(logFile, "utf8").includes("pre-delay")) return resolve();
+          setTimeout(check, 10);
+        } catch { setTimeout(check, 10); }
+      };
+      setTimeout(() => reject(new Error("timed out waiting for pre-delay in log")), 2000);
+      check();
+    });
+
+    await childPromise;
+
+    // After completion, the log file contains all output
+    const fullLog = fs.readFileSync(logFile, "utf8");
+    assert.match(fullLog, /pre-delay/);
+    assert.match(fullLog, /post-delay/);
+  } finally {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+  }
+});
+
+test("logFilePath: stderr tee is also captured in the log file", async () => {
+  const tmpDir = fs.mkdtempSync("/tmp/agent-workflow-tee-test-");
+  try {
+    const logFile = path.join(tmpDir, "exec.log");
+    const { stream } = collectSink();
+    const r = await spawnStreamingChild(
+      process.execPath,
+      ["-e", "process.stderr.write('stderr-msg\\n'); process.stdout.write('stdout-msg\\n');"],
+      { stdoutSink: stream, stderrSink: stream, logFilePath: logFile },
+    );
+    assert.equal(r.status, 0);
+    const logContent = fs.readFileSync(logFile, "utf8");
+    assert.match(logContent, /stderr-msg/);
+    assert.match(logContent, /stdout-msg/);
+  } finally {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+  }
+});
+
+test("logFilePath: Chinese UTF-8 is preserved correctly", async () => {
+  const tmpDir = fs.mkdtempSync("/tmp/agent-workflow-utf8-test-");
+  try {
+    const logFile = path.join(tmpDir, "exec.log");
+    const { stream } = collectSink();
+    const r = await spawnStreamingChild(
+      process.execPath,
+      ["-e", "console.log('你好世界'); console.log('日本語'); console.log('🚀');"],
+      { stdoutSink: stream, stderrSink: stream, logFilePath: logFile },
+    );
+    assert.equal(r.status, 0);
+    const logContent = fs.readFileSync(logFile, "utf8");
+    assert.match(logContent, /你好世界/);
+    assert.match(logContent, /日本語/);
+    assert.match(logContent, /🚀/);
+  } finally {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+  }
+});
+
+test("logFilePath: onProgress reports pid and bytesLogged", async () => {
+  const tmpDir = fs.mkdtempSync("/tmp/agent-workflow-progress-test-");
+  try {
+    const logFile = path.join(tmpDir, "exec.log");
+    const { stream } = collectSink();
+    const progressUpdates: Array<{ pid?: number; bytesLogged: number }> = [];
+    const r = await spawnStreamingChild(
+      process.execPath,
+      ["-e", "process.stdout.write('hello world');"],
+      {
+        stdoutSink: stream,
+        stderrSink: stream,
+        logFilePath: logFile,
+        onProgress: (info) => { progressUpdates.push(info); },
+      },
+    );
+    assert.equal(r.status, 0);
+    assert.ok(progressUpdates.length >= 1);
+    assert.ok(progressUpdates.some((p) => p.bytesLogged > 0));
+    if (progressUpdates[0].pid) assert.ok(progressUpdates[0].pid! > 0);
+  } finally {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+  }
+});
+
+test("logFilePath: write stream error resolves spawnStreamingChild with result.error", async () => {
+  const tmpDir = fs.mkdtempSync("/tmp/agent-workflow-log-err-test-");
+  try {
+    // Parent does not exist → ENOENT on first write
+    const badLogFile = path.join(tmpDir, "nonexistent", "exec.log");
+
+    const { stream } = collectSink();
+    const r = await spawnStreamingChild(
+      process.execPath,
+      ["-e", "console.log('hello');"],
+      {
+        stdoutSink: stream,
+        stderrSink: stream,
+        logFilePath: badLogFile,
+      },
+    );
+    assert.equal(r.status, 0);
+    assert.ok(r.error !== undefined, "expected result.error from log stream failure");
+    assert.match(String(r.error), /ENOENT|no such file|open/);
+  } finally {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+  }
+});