Regression: stream disconnected before completion on Windows in 0.100.0+ (works in 0.99.0)

What version of Codex CLI is running?

Failing versions: 0.100.x 0.101.0 Working version: 0.99.0

What subscription do you have?

ChatGPT Pro

Which model were you using?

Observed with default CLI model (gpt-5.2-codex). Issue appears transport-related rather than model-specific.

What platform is your computer?

Windows 11 (x64)

What terminal emulator and version are you using (if applicable)?

Windows Command Prompt (cmd.exe)

What issue are you seeing?

When running Codex CLI 0.100.0+:

Falling back from WebSockets to HTTPS transport
stream disconnected before completion

Behavior:

• WebSocket transport fails
• CLI falls back to HTTPS (SSE)
• SSE stream disconnects before completion
• Response does not finish

What steps can reproduce the bug?

1. Install latest CLI:

npm i -g @openai/codex@latest

1. Run:

codex

1. Send any normal prompt.

1. Observe stream disconnection before completion.

Downgrading fixes it:
npm i -g @openai/codex@0.99.0

After downgrade:

• Streaming works normally
• No transport fallback message
• No disconnection

What is the expected behavior?

Streaming response should complete normally without transport fallback or premature disconnection.

Additional information

• Reproduces on:
• Home network
• Mobile hotspot

• No proxy configured:
• HTTP_PROXY not set
• HTTPS_PROXY not set
• netsh winhttp show proxy → Direct access (no proxy)

• No VPN enabled.

Because:

• Network changes do not affect behavior
• Proxy is not configured
• Downgrading to 0.99.0 fully resolves the issue

This strongly suggests a regression introduced in 0.100.0+, likely related to WebSocket transport reintroduction or WebSocket → HTTPS fallback streaming handling on Windows.