fix: use fs.writeSync for stdout to prevent pipe truncation

process.stdout.write() is async when stdout is a pipe. The
immediate process.exit(0) tears down the process before the
downstream reader (jq, python3, etc) consumes the buffer,
producing truncated JSON.

Replace with fs.writeSync(1, data) which blocks until the
kernel pipe buffer accepts the bytes, and drop process.exit(0)
on the success path so the event loop drains naturally.

Fixes #1275
Related: #493 (addressed >50KB case, this fixes <50KB)

get-shit-done/bin/lib/core.cjs

@@ -147,8 +147,9 @@ function reapStaleTempFiles(prefix = 'gsd-', { maxAgeMs = 5 * 60 * 1000, dirsOnl
 }
 
 function output(result, raw, rawValue) {
+  let data;
   if (raw && rawValue !== undefined) {
-    process.stdout.write(String(rawValue));
+    data = String(rawValue);
   } else {
     const json = JSON.stringify(result, null, 2);
     // Large payloads exceed Claude Code's Bash tool buffer (~50KB).
@@ -157,16 +158,20 @@ function output(result, raw, rawValue) {
       reapStaleTempFiles();
       const tmpPath = path.join(require('os').tmpdir(), `gsd-${Date.now()}.json`);
       fs.writeFileSync(tmpPath, json, 'utf-8');
-      process.stdout.write('@file:' + tmpPath);
+      data = '@file:' + tmpPath;
     } else {
-      process.stdout.write(json);
+      data = json;
     }
   }
-  process.exit(0);
+  // process.stdout.write() is async when stdout is a pipe — process.exit()
+  // can tear down the process before the reader consumes the buffer.
+  // fs.writeSync(1, ...) blocks until the kernel accepts the bytes, and
+  // skipping process.exit() lets the event loop drain naturally.
+  fs.writeSync(1, data);
 }
 
 function error(message) {
-  process.stderr.write('Error: ' + message + '\n');
+  fs.writeSync(2, 'Error: ' + message + '\n');
   process.exit(1);
 }