fix(stats): avoided native jsonl parser trap

Replaced the stats session parser's Bun.JSONL.parseChunk path with a lenient JS line scanner so large session files do not enter the native parser before /stats launches.

Fixes #3733

packages/stats/CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Fixed
 
 - Kept stats session sync on the serial parser path for `workers: 1` and macOS defaults, avoiding Bun worker re-entry aborts when launching `/stats` ([#3733](https://github.com/can1357/oh-my-pi/issues/3733)).
+- Replaced the native `Bun.JSONL.parseChunk` session parser path with a lenient JS line scanner, avoiding Bun aborts on large stats session files ([#3733](https://github.com/can1357/oh-my-pi/issues/3733)).
 
 ## [16.2.3] - 2026-06-28
 

packages/stats/src/parser.ts

@@ -164,54 +164,53 @@ function extractStats(
 }
 
 const LF = 0x0a;
+const CR = 0x0d;
+const jsonLineDecoder = new TextDecoder();
+
+function parseJsonLine(bytes: Uint8Array, start: number, end: number): SessionEntry | null {
+	while (end > start && bytes[end - 1] === CR) end--;
+	if (end <= start) return null;
+	try {
+		return JSON.parse(jsonLineDecoder.decode(bytes.subarray(start, end))) as SessionEntry;
+	} catch {
+		return null;
+	}
+}
+
+function visitSessionEntriesLenient(bytes: Uint8Array, visit: (entry: SessionEntry) => void): number {
+	let cursor = 0;
+	let read = 0;
+
+	while (cursor < bytes.length) {
+		const newline = bytes.indexOf(LF, cursor);
+		const hasNewline = newline !== -1;
+		const lineEnd = hasNewline ? newline : bytes.length;
+		const entry = parseJsonLine(bytes, cursor, lineEnd);
+		if (entry) {
+			visit(entry);
+			read = hasNewline ? newline + 1 : lineEnd;
+		} else if (hasNewline) {
+			read = newline + 1;
+		} else {
+			break;
+		}
+		cursor = hasNewline ? newline + 1 : lineEnd;
+	}
+
+	return read;
+}
 
 function parseSessionEntriesLenient(bytes: Uint8Array): { entries: SessionEntry[]; read: number } {
 	const entries: SessionEntry[] = [];
-	let cursor = 0;
-
-	while (cursor < bytes.length) {
-		const { values, error, read, done } = Bun.JSONL.parseChunk(bytes, cursor, bytes.length);
-		if (values.length > 0) {
-			entries.push(...(values as SessionEntry[]));
-		}
-
-		if (error) {
-			const nextNewline = bytes.indexOf(LF, Math.max(read, cursor));
-			if (nextNewline === -1) break;
-			cursor = nextNewline + 1;
-			continue;
-		}
-
-		if (read <= cursor) break;
-		cursor = read;
-		if (done) break;
-	}
-
-	return { entries, read: cursor };
+	const read = visitSessionEntriesLenient(bytes, entry => entries.push(entry));
+	return { entries, read };
 }
 
 function scanLastServiceTier(bytes: Uint8Array): ServiceTier | undefined {
-	let cursor = 0;
 	let currentServiceTier: ServiceTier | undefined;
-
-	while (cursor < bytes.length) {
-		const { values, error, read, done } = Bun.JSONL.parseChunk(bytes, cursor, bytes.length);
-		for (const value of values as SessionEntry[]) {
-			if (isServiceTierChange(value)) currentServiceTier = value.serviceTier ?? undefined;
-		}
-
-		if (error) {
-			const nextNewline = bytes.indexOf(LF, Math.max(read, cursor));
-			if (nextNewline === -1) break;
-			cursor = nextNewline + 1;
-			continue;
-		}
-
-		if (read <= cursor) break;
-		cursor = read;
-		if (done) break;
-	}
-
+	visitSessionEntriesLenient(bytes, entry => {
+		if (isServiceTierChange(entry)) currentServiceTier = entry.serviceTier ?? undefined;
+	});
 	return currentServiceTier;
 }
 /**

packages/stats/test/parser-large-session.test.ts

@@ -0,0 +1,83 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "bun:test";
+import * as fs from "node:fs/promises";
+import * as os from "node:os";
+import * as path from "node:path";
+import { parseSessionFile } from "@oh-my-pi/omp-stats/parser";
+import { getAgentDir, getSessionsDir, setAgentDir, TempDir } from "@oh-my-pi/pi-utils";
+
+const originalConfigDir = process.env.PI_CONFIG_DIR;
+const originalAgentDir = getAgentDir();
+let tempDir: TempDir | null = null;
+
+beforeEach(() => {
+	tempDir = TempDir.createSync("@pi-stats-large-session-");
+	const configDir = path.relative(os.homedir(), tempDir.join("config"));
+	process.env.PI_CONFIG_DIR = configDir;
+	setAgentDir(tempDir.join("agent"));
+});
+
+afterEach(() => {
+	vi.restoreAllMocks();
+	if (originalConfigDir === undefined) {
+		delete process.env.PI_CONFIG_DIR;
+	} else {
+		process.env.PI_CONFIG_DIR = originalConfigDir;
+	}
+	setAgentDir(originalAgentDir);
+	tempDir?.removeSync();
+	tempDir = null;
+});
+
+async function writeLargeSessionFile(): Promise<string> {
+	const sessionDir = path.join(getSessionsDir(), "--tmp--large-session");
+	await fs.mkdir(sessionDir, { recursive: true });
+	const sessionFile = path.join(sessionDir, "session.jsonl");
+	const timestamp = new Date().toISOString();
+	const payload = "x".repeat(16 * 1024);
+	const lines: string[] = [];
+	for (let i = 0; i < 256; i++) {
+		lines.push(
+			JSON.stringify({
+				type: "message",
+				id: `assistant-${i}`,
+				parentId: null,
+				timestamp,
+				message: {
+					role: "assistant",
+					content: [{ type: "text", text: payload }],
+					api: "openai-responses",
+					provider: "openai",
+					model: "gpt-5.4",
+					usage: {
+						input: 1,
+						output: 2,
+						cacheRead: 0,
+						cacheWrite: 0,
+						totalTokens: 3,
+						cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+					},
+					stopReason: "stop",
+					timestamp: Date.now() + i,
+					duration: 10,
+					ttft: 5,
+				},
+			}),
+		);
+	}
+	await Bun.write(sessionFile, `${lines.join("\n")}\n`);
+	return sessionFile;
+}
+
+describe("large session parsing", () => {
+	it("parses multi-megabyte JSONL without entering Bun.JSONL.parseChunk", async () => {
+		const sessionFile = await writeLargeSessionFile();
+		vi.spyOn(Bun.JSONL, "parseChunk").mockImplementation(() => {
+			throw new Error("native JSONL parser unavailable");
+		});
+
+		const result = await parseSessionFile(sessionFile);
+
+		expect(result.stats).toHaveLength(256);
+		expect(result.newOffset).toBeGreaterThan(4 * 1024 * 1024);
+	});
+});