fix: prevent process hang on Windows when stdin EOF does not propagate through Volta shim

[FelixIsaac]

Problem

On Windows with a Volta-managed ccstatusline, spawning ccstatusline as a child subprocess causes it to hang indefinitely. The process chain:

parent node → cmd.exe (shell:true) → bash (Volta shim) → volta → node (ccstatusline)

The for await (const chunk of process.stdin) loop never terminates because stdin EOF from the parent does not propagate through cmd.exe → bash → volta on Windows. Claude Code's statusline lifecycle abandons (does not kill) processes that take too long — so each refresh leaks one hung node.exe process.

Real-world impact: 961 leaked node.exe processes, 2.1 GB RAM, 90.5% kernel-mode CPU from Windows scheduler overhead managing ~1000 sleeping processes.

This is a known Windows/Node.js behavior:

• Piping process.stdin to child.stdin leaves behind an open handle nodejs/node#32291 — piping stdin to child.stdin leaves open handle
• spawn with stdio/stdin 'pipe' options causes pwsh shell to hang after execution nodejs/node#52364 — spawn + stdin:pipe causes pwsh to hang (2024)
• Volta breaks with child_process.exec in cmd (Windows) volta-cli/volta#1199 — Volta shims + child_process broken on Windows cmd
• [Bug] ccusage statusline causes infinite process spawning loop leading to 100% CPU usage ryoppippi/ccusage#459 — identical failure mode in Claude Code ecosystem (same fix applied)

Note: the normal use case ("command": "ccstatusline" direct from Claude Code) is not affected — Claude Code pipes directly, single process layer, EOF works correctly.

Fix

Fix 1 — readStdin(): Replace for await with event-based reading + 3s bail timeout. When EOF never arrives (Volta chain), the timeout destroys stdin and resolves the Promise. Data already accumulated in chunks[] is preserved and returned normally — no data loss.

Fix 2 — main(): Add explicit process.exit(0) after renderMultipleLines. Claude Code's "abandon not kill" lifecycle means any residual async handles from rendering keep the process alive indefinitely. An explicit exit prevents accumulation.

Build note

Bun was not available in this environment so dist/ was not rebuilt. The source change is in src/ccstatusline.ts only — maintainer build required before publishing.