⚡ Bolt: Optimize sequential gh CLI calls by parallelizing pr list checks

.jules/bolt.md

@@ -0,0 +1,3 @@
+## 2026-05-27 - Parallelize gh CLI calls
+**Learning:** Subprocess calls to the GitHub CLI ('gh') are a significant performance bottleneck. When checking states for multiple PRs sequentially, it creates an N+1 delay issue.
+**Action:** Use concurrency (e.g., `concurrent.futures.ThreadPoolExecutor`) to eliminate sequential delays when making multiple independent subprocess CLI calls (e.g., checking PR open states). Ensure the original order is preserved by using `executor.map`.

ralph_loop/cli.py

@@ -2,6 +2,7 @@
 from __future__ import annotations
 
 import argparse
+import concurrent.futures
 import os
 import re
 import shlex
@@ -544,23 +545,28 @@ def _filter_to_still_open_prs(pr_numbers: List[int]) -> List[int]:
     swallow stale PRs because of a flaky network.
     """
     kept: List[int] = []
-    for pr in pr_numbers:
+
+    def _check_pr(pr: int) -> Tuple[int, bool, Optional[CommandError]]:
         try:
-            still_open = _pr_is_still_open(pr)
+            return pr, _pr_is_still_open(pr), None
         except CommandError as exc:
-            _print_step(
-                "Could not confirm PR #{} open state ({}); keeping it in the "
-                "fan-out set.".format(pr, exc)
-            )
-            kept.append(pr)
-            continue
-        if still_open:
-            kept.append(pr)
-        else:
-            _print_step(
-                "PR #{} is no longer open (per gh pr view); skipping "
-                "fan-out spawn.".format(pr)
-            )
+            return pr, True, exc
+
+    with concurrent.futures.ThreadPoolExecutor(max_workers=10) as executor:
+        for pr, still_open, exc in executor.map(_check_pr, pr_numbers):
+            if exc:
+                _print_step(
+                    "Could not confirm PR #{} open state ({}); keeping it in the "
+                    "fan-out set.".format(pr, exc)
+                )
+                kept.append(pr)
+            elif still_open:
+                kept.append(pr)
+            else:
+                _print_step(
+                    "PR #{} is no longer open (per gh pr view); skipping "
+                    "fan-out spawn.".format(pr)
+                )
     return kept