fix: flush large activity output

src/ai.ts

@@ -31,6 +31,7 @@ import {
   withFacultRootScope,
 } from "./paths";
 import { redactReconciliationText } from "./reconciliation-adapters";
+import { writeCliOutput } from "./util/cli-output";
 
 const NEWLINE_RE = /\r?\n/;
 const TRAILING_NEWLINE_RE = /\n$/;
@@ -3118,7 +3119,7 @@ async function loopCommand(argv: string[]) {
           homeDir,
           globalRootDir,
         });
-        console.log(
+        await writeCliOutput(
           json ? JSON.stringify(result, null, 2) : renderActivitySet(result)
         );
         return;
@@ -3131,7 +3132,7 @@ async function loopCommand(argv: string[]) {
       if (!result) {
         throw new Error("No evolution loop report has been recorded");
       }
-      console.log(
+      await writeCliOutput(
         json ? JSON.stringify(result, null, 2) : renderActivityFeed(result)
       );
       return;
@@ -3206,7 +3207,7 @@ async function loopCommand(argv: string[]) {
         },
         async () => await queryActivityHistory(queryArgs)
       );
-      console.log(
+      await writeCliOutput(
         json ? JSON.stringify(result, null, 2) : renderActivityHistory(result)
       );
       return;

src/util/cli-output.test.ts

@@ -0,0 +1,28 @@
+import { describe, expect, it } from "bun:test";
+
+describe("writeCliOutput", () => {
+  it("flushes output larger than Bun's buffered stdout window", async () => {
+    const expectedBytes = 200_001;
+    const proc = Bun.spawn(
+      [
+        process.execPath,
+        "-e",
+        'import { writeCliOutput } from "./src/util/cli-output"; await writeCliOutput("x".repeat(200_000));',
+      ],
+      {
+        cwd: process.cwd(),
+        stdout: "pipe",
+        stderr: "pipe",
+      }
+    );
+    const [exitCode, stdout, stderr] = await Promise.all([
+      proc.exited,
+      new Response(proc.stdout).arrayBuffer(),
+      new Response(proc.stderr).text(),
+    ]);
+
+    expect(exitCode).toBe(0);
+    expect(stderr).toBe("");
+    expect(stdout.byteLength).toBe(expectedBytes);
+  });
+});

src/util/cli-output.ts

@@ -0,0 +1,19 @@
+const BUFFERED_STDOUT_THRESHOLD_BYTES = 64 * 1024;
+
+export async function writeCliOutput(output: string): Promise<void> {
+  const terminated = `${output}\n`;
+  if (Buffer.byteLength(terminated, "utf8") < BUFFERED_STDOUT_THRESHOLD_BYTES) {
+    console.log(output);
+    return;
+  }
+
+  await new Promise<void>((resolve, reject) => {
+    process.stdout.write(terminated, (error) => {
+      if (error) {
+        reject(error);
+        return;
+      }
+      resolve();
+    });
+  });
+}