From 4c9a557533a7f55acaa375c706f368471510a149 Mon Sep 17 00:00:00 2001
From: Marvinthebored <peter@lindsey.jp>
Date: Sun, 3 May 2026 11:01:41 +0800
Subject: [PATCH] fix(gateway): skip oversized JSONL lines to prevent
 event-loop starvation

Large transcript JSONL records (multi-MB tool results, file content)
block the event loop via JSON.parse before truncation logic can skip
them. Add a 256 KiB line-size guard to parseTailTranscriptRecord and
extractUsageSnapshotFromTranscriptLine, and replace the full transcript
index scan in readSessionTitleFieldsFromTranscriptAsync with the
existing bounded sync reader.

Observed improvement on a production install (33 sessions):
chat.history dropped from 13-16s to ~1.2s, event loop utilization
from 0.999 to normal, steady-state CPU from ~100% to 0.2-0.3%.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>