From 482bbf678b541b28a45f317282bb6ed8b9df8f2d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?T=C3=82CHES?= <afromanguy@me.com>
Date: Tue, 17 Mar 2026 17:05:35 -0600
Subject: [PATCH] fix: deduplicate parseJSONL and unify MAX_JSONL_BYTES
 constant (#985)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 src/resources/extensions/gsd/forensics.ts     | 12 +----------
 src/resources/extensions/gsd/jsonl-utils.ts   | 21 +++++++++++++++++++
 .../extensions/gsd/session-forensics.ts       | 17 ++-------------
 3 files changed, 24 insertions(+), 26 deletions(-)
 create mode 100644 src/resources/extensions/gsd/jsonl-utils.ts

diff --git a/src/resources/extensions/gsd/forensics.ts b/src/resources/extensions/gsd/forensics.ts
index a9dcc7b84..0efe2e326 100644
--- a/src/resources/extensions/gsd/forensics.ts
+++ b/src/resources/extensions/gsd/forensics.ts
@@ -15,6 +15,7 @@ import { fileURLToPath } from "node:url";
 
 import { extractTrace, type ExecutionTrace } from "./session-forensics.js";
 import { nativeParseJsonlTail } from "./native-parser-bridge.js";
+import { MAX_JSONL_BYTES, parseJSONL } from "./jsonl-utils.js";
 import {
   loadLedgerFromDisk, getAverageCostPerUnitType, getProjectTotals,
   formatCost, formatTokenCount, type UnitMetrics, type MetricsLedger,
@@ -65,17 +66,6 @@ interface ForensicReport {
   recentUnits: { type: string; id: string; cost: number; duration: number; model: string; finishedAt: number }[];
 }
 
-// ─── JSONL Parser (inline — session-forensics.ts version is module-private) ──
-
-const MAX_JSONL_BYTES = 5 * 1024 * 1024;
-
-function parseJSONL(raw: string): unknown[] {
-  const source = raw.length > MAX_JSONL_BYTES ? raw.slice(-MAX_JSONL_BYTES) : raw;
-  return source.trim().split("\n").map(line => {
-    try { return JSON.parse(line); } catch { return null; }
-  }).filter(Boolean) as unknown[];
-}
-
 // ─── Entry Point ──────────────────────────────────────────────────────────────
 
 export async function handleForensics(
diff --git a/src/resources/extensions/gsd/jsonl-utils.ts b/src/resources/extensions/gsd/jsonl-utils.ts
new file mode 100644
index 000000000..4e0de6112
--- /dev/null
+++ b/src/resources/extensions/gsd/jsonl-utils.ts
@@ -0,0 +1,21 @@
+/**
+ * Shared JSONL parsing utilities.
+ *
+ * Both forensics.ts and session-forensics.ts need to parse JSONL activity logs
+ * with an upper byte limit to prevent V8 OOM on bloated files. This module
+ * provides the single canonical implementation and constant.
+ */
+
+/** Max bytes to parse from a JSONL source. Prevents V8 OOM on bloated activity logs. */
+export const MAX_JSONL_BYTES = 10 * 1024 * 1024; // 10 MB
+
+/**
+ * Parse a raw JSONL string into an array of parsed objects.
+ * If the input exceeds MAX_JSONL_BYTES, only the tail is parsed (most recent entries).
+ */
+export function parseJSONL(raw: string): unknown[] {
+  const source = raw.length > MAX_JSONL_BYTES ? raw.slice(-MAX_JSONL_BYTES) : raw;
+  return source.trim().split("\n").map(line => {
+    try { return JSON.parse(line); } catch { return null; }
+  }).filter(Boolean) as unknown[];
+}
diff --git a/src/resources/extensions/gsd/session-forensics.ts b/src/resources/extensions/gsd/session-forensics.ts
index 4db0a2e12..7e293eab9 100644
--- a/src/resources/extensions/gsd/session-forensics.ts
+++ b/src/resources/extensions/gsd/session-forensics.ts
@@ -21,6 +21,7 @@
 import { readFileSync, readdirSync, existsSync, statSync } from "node:fs";
 import { basename, join } from "node:path";
 import { nativeParseJsonlTail } from "./native-parser-bridge.js";
+import { MAX_JSONL_BYTES, parseJSONL } from "./jsonl-utils.js";
 import { nativeWorkingTreeStatus, nativeDiffStat } from "./native-git-bridge.js";
 import { getAutoWorktreePath } from "./auto-worktree.js";
 
@@ -63,21 +64,7 @@ export interface RecoveryBriefing {
 }
 
 // ─── JSONL Parsing ────────────────────────────────────────────────────────────
-
-/** Max bytes to parse from a JSONL source. Prevents V8 OOM on bloated activity logs. */
-const MAX_JSONL_BYTES = 10 * 1024 * 1024; // 10 MB
-
-function parseJSONL(raw: string): unknown[] {
-  // If the file is enormous, only parse the tail (most recent entries).
-  // This prevents the OOM crash path: large file → split → map → parse → OOM.
-  const source = raw.length > MAX_JSONL_BYTES
-    ? raw.slice(-MAX_JSONL_BYTES)
-    : raw;
-  return source.trim().split("\n").map(line => {
-    try { return JSON.parse(line); }
-    catch { return null; }
-  }).filter(Boolean) as unknown[];
-}
+// MAX_JSONL_BYTES and parseJSONL are imported from ./jsonl-utils.js
 
 /**
  * Find the entries belonging to the last session in a JSONL file.