Frequent crashes on WSL2 ARM64: setRawMode EIO kills sessions mid-work

[ronniegeraghty]

Description

Copilot CLI crashes frequently on WSL2 (Ubuntu 24.04, aarch64) with setRawMode EIO errors. The process loses its stdin connection mid-session and shuts down. This is happening multiple times per day — 21 crashes in the past 8 days, with 13 on a single day.

This is distinct from #2088 (React hooks rendering error). The crash signature here is a terminal stdin disconnection, not a rendering bug.

Environment

• OS: Ubuntu 24.04.4 LTS on WSL2
• Kernel: 6.6.87.2-microsoft-standard-WSL2
• Architecture: aarch64 (ARM64)
• Terminal: VS Code Insiders integrated terminal (github.copilot-chat v0.42.2026032703)
• Node.js: v18.19.1
• Copilot CLI: 1.0.13-1 (installed via npm install -g @github/copilot)
• Shell: bash

Crash Signature

From the process logs (~/.copilot/logs/process-*.log):

2026-03-28T18:20:57.662Z [DEBUG] [shutdown] Starting dispose: InkInstance.rerender
2026-03-28T18:20:57.679Z [DEBUG] Ignoring transient stdin error: setRawMode EIO
2026-03-28T18:20:57.679Z [INFO] Unregistering foreground session: fd8423ed-...

The pattern is consistent across all 21 crashes:

1. Session is running normally (often during background agent work or tool calls)
2. setRawMode EIO — stdin connection to the terminal is severed
3. Session shuts down, losing all in-progress work

Frequency

Date	Crashes
2026-03-21	1
2026-03-23	2
2026-03-25	1
2026-03-26	1
2026-03-27	2
2026-03-28	13
2026-03-29	1

The acceleration on Mar 28 correlates with heavier usage (multi-agent workflows with --agent flag), but crashes also occur during simple single-agent sessions.

Reproduction

Not reliably reproducible on demand, but happens consistently during extended sessions (10-60 minutes). More frequent when:

• Using copilot --agent squad (custom agent with sub-agent spawning)
• Multiple background tool calls running in parallel
• Sessions lasting >15 minutes

What I've Tried

• Version pinning: Does not work. All npm versions (@github/copilot@1.0.5 through @latest) and all GitHub Release tags (v1.0.5 through v1.0.12) deliver the identical 1.0.13-1 binary. Old binaries are not preserved in the registry.
• Clean reinstall: npm cache clean --force + sudo npm install -g @github/copilot@latest — crashes persist
• Removing duplicate installs: Had both curl (~/.local/bin/copilot) and npm (/usr/local/bin/copilot) — removed curl install, no improvement
• --no-auto-update: Using this flag to prevent mid-session updates

Expected Behavior

Sessions should survive stdin interruptions gracefully (reconnect or buffer) rather than terminating. At minimum, the CLI should save session state before shutting down so --resume can recover.

Additional Context

• Related: "Rendered more hooks than during the previous render" error occurs #2088 (React hooks error, different crash signature but also on WSL2)
• Related: Copilot cli needs to be more resilient to crashes/unexpected shutdown and recover from them better. #2217 (CLI resilience to crashes, requests better recovery)
• Context utilization at crash time is typically 5-17% — this is NOT a context overflow issue
• The EIO error suggests the WSL2↔Windows terminal pipe is being dropped, possibly by the VS Code terminal host