perf(noema): parallelize bounded changed-file evidence fetches

.jules/bolt.md

@@ -43,3 +43,6 @@
 ## 2026-07-09 - Avoid N+1 API blocking in SBOM aggregator
 **Learning:** The `collect_inventories` function in `scripts/ci/sbom_inventory_aggregator.py` was fetching SBOMs from the GitHub dependency graph synchronously for every repository in the organization. For large organizations (up to 500 repos), this N+1 network/CLI bottleneck significantly stalled the aggregation workflow.
 **Action:** Use `concurrent.futures.ThreadPoolExecutor` to fetch SBOMs concurrently when multiple repositories are provided, bounded by a `max_workers` limit (e.g., 10) to avoid overwhelming the CLI/API, while preserving the fast serial path for single-item inputs.
+## 2024-05-25 - Avoid N+1 API blocking in Noema review gate
+**Learning:** In `scripts/ci/noema_review_gate.py`, the `changed_file_context` function was sequentially fetching changed file contents using `fetch_head_file_content` via the GitHub API. This N+1 network/CLI bottleneck significantly stalled the review process linearly for pull requests with many changed files.
+**Action:** Use `concurrent.futures.ThreadPoolExecutor` to fetch file contents concurrently for multiple changed paths, bounded by a `max_workers` limit to avoid overwhelming the API.

patch.diff

@@ -0,0 +1,45 @@
+--- a/scripts/ci/noema_review_gate.py
++++ b/scripts/ci/noema_review_gate.py
+@@ -5,6 +5,7 @@
+
+ import argparse
+ import base64
++import concurrent.futures
+ import ipaddress
+ import json
+ import os
+@@ -343,17 +343,31 @@
+     if not paths:
+         return "Changed file context unavailable: PR reported no changed files."
+     sections: list[str] = []
+-    for path in paths[:MAX_CONTEXT_FILES]:
++
++    target_paths = paths[:MAX_CONTEXT_FILES]
++    if not target_paths:
++        return "Changed file context unavailable: no paths to check."
++
++    def _fetch_file_content(path: str) -> tuple[str, str | None, str | None]:
+         try:
+             content = fetch_head_file_content(repo, path, head_sha)
++            return path, content, None
+         except RuntimeError as exc:
+-            reason = scrub_sensitive_data(str(exc)) or "unknown error"
+-            sections.append(f"### {path}\nUnavailable from head content API: {reason}")
++            return path, None, scrub_sensitive_data(str(exc)) or "unknown error"
++
++    max_workers = min(10, len(target_paths))
++    with concurrent.futures.ThreadPoolExecutor(max_workers=max_workers) as executor:
++        results = list(executor.map(_fetch_file_content, target_paths))
++
++    for path, content, error in results:
++        if error:
++            sections.append(f"### {path}\nUnavailable from head content API: {error}")
+             continue
+         if not content:
+             sections.append(f"### {path}\nNo UTF-8 text content available from head content API.")
+             continue
+         sections.append(f"### {path}\n{truncate_text(content, MAX_FILE_CONTEXT_CHARS)}")
++
+     if len(paths) > MAX_CONTEXT_FILES:
+         sections.append(f"[{len(paths) - MAX_CONTEXT_FILES} changed files omitted from context budget]")
+     return "\n\n".join(sections)

scripts/ci/noema_review_gate.py

@@ -5,6 +5,7 @@
 
 import argparse
 import base64
+import concurrent.futures
 import ipaddress
 import json
 import os
@@ -342,17 +343,31 @@ def changed_file_context(repo: str, number: int, head_sha: str) -> str:
     if not paths:
         return "Changed file context unavailable: PR reported no changed files."
     sections: list[str] = []
-    for path in paths[:MAX_CONTEXT_FILES]:
+
+    target_paths = paths[:MAX_CONTEXT_FILES]
+    if not target_paths:
+        return "Changed file context unavailable: no paths to check."
+
+    def _fetch_file_content(path: str) -> tuple[str, str | None, str | None]:
         try:
             content = fetch_head_file_content(repo, path, head_sha)
+            return path, content, None
         except RuntimeError as exc:
-            reason = scrub_sensitive_data(str(exc)) or "unknown error"
-            sections.append(f"### {path}\nUnavailable from head content API: {reason}")
+            return path, None, scrub_sensitive_data(str(exc)) or "unknown error"
+
+    max_workers = min(10, len(target_paths))
+    with concurrent.futures.ThreadPoolExecutor(max_workers=max_workers) as executor:
+        results = list(executor.map(_fetch_file_content, target_paths))
+
+    for path, content, error in results:
+        if error:
+            sections.append(f"### {path}\nUnavailable from head content API: {error}")
             continue
         if not content:
             sections.append(f"### {path}\nNo UTF-8 text content available from head content API.")
             continue
         sections.append(f"### {path}\n{truncate_text(content, MAX_FILE_CONTEXT_CHARS)}")
+
     if len(paths) > MAX_CONTEXT_FILES:
         sections.append(f"[{len(paths) - MAX_CONTEXT_FILES} changed files omitted from context budget]")
     return "\n\n".join(sections)