VS Code: support per-chat Codex app-server lifecycle instead of global window reload

Summary

Please add a VS Code lifecycle equivalent to Claude Code's extension: each Codex chat/editor panel should own the backend process/session resources it needs, and closing that panel should shut those resources down, including the local codex.exe app-server and its child processes when they are panel-scoped.

Today the OpenAI/Codex VS Code extension appears to start one shared local Codex app-server for the entire extension host. That makes a Codex reload require either a global VS Code window reload or a singleton app-server restart, both of which are operationally worse than Claude Code's per-panel lifecycle.

Why this matters

I often run multiple agents simultaneously in the same VS Code window, for example Claude Code plus ChatGPT/Codex. When only the Codex agent needs a reload, such as after an MCP server/config change, using Developer: Reload Window interrupts every active agent and extension in the window.

Claude Code's VS Code extension behaves better for this workflow: closing the Claude chat tab tears down the resources for that specific chat, including claude.exe, so I can restart only that agent without disrupting the rest of VS Code.

Environment

• OS: Windows
• VS Code extension: openai.chatgpt version 26.513.21555 (openai.chatgpt-26.513.21555-win32-x64)
• Claude comparison extension: anthropic.claude-code version 2.1.142 (anthropic.claude-code-2.1.142-win32-x64)
• Codex binary path observed locally: ~/.vscode/extensions/openai.chatgpt-26.513.21555-win32-x64/bin/windows-x86_64/codex.exe
• Claude binary path observed locally: ~/.vscode/extensions/anthropic.claude-code-2.1.142-win32-x64/resources/native-binary/claude.exe

Observed behavior in Claude Code VS Code extension

From the installed Claude extension bundle, the panel path creates a per-panel communication/process object:

• setupPanel(...) creates a new m3(...) instance for the WebviewPanel.
• The panel dispose hook calls H.shutdown():
• z.onDidDispose(() => { H.shutdown(); ... })
• m3.shutdown() aborts active controllers, closes all channels, drains pending channel ops, and tears down the subprocess path.
• The lower process transport closes stdin and sends termination (SIGTERM, then SIGKILL after timeout) if the process remains alive.

Operationally, closing a Claude Code chat tab terminates the corresponding claude.exe process tree.

Observed behavior in OpenAI/Codex VS Code extension

From the installed OpenAI/Codex extension bundle:

• Activation creates a single app-server connection:
• let d = new I_(t.extensionUri, l);
• let m = d.startCodexProcess();
• That singleton d is then passed into shared providers and the main webview provider, including wl, R_, dR, auth/preview/fetch paths, etc.
• The main provider stores one this.codexMcpConnection and uses it across sidebar and editor panels.
• registerOnDidDisposeForWebviewPanel(...) clears pending webview requests and removes the panel, but does not shut down a panel-specific app-server because there is no panel-specific app-server.
• The webview message codex-app-server-restart currently routes to workbench.action.reloadWindow, which reloads the whole VS Code window instead of only Codex.

This means closing a Codex task/editor tab does not terminate codex.exe; the process remains shared by the whole extension. If Codex needs a backend reload, the current UX pushes toward a full window reload, interrupting other agents.

Requested behavior

Preferred:

• Make each Codex chat/editor panel/session own a CodexMcpConnection / app-server lifecycle, similar to Claude Code's m3 per-panel model.
• On WebviewPanel.onDidDispose / custom editor dispose, gracefully shut down the backend process/session for that panel.
• Ensure subprocesses are terminated as part of the panel lifecycle.
• Reopening the chat should create a fresh app-server/session without requiring workbench.action.reloadWindow.

Acceptable fallback if a fully per-panel process model is not currently viable:

• Add an official Restart Codex App Server command for the VS Code extension that restarts only the Codex app-server process and preserves the VS Code extension host/window.
• Replace the current codex-app-server-restart -> workbench.action.reloadWindow behavior with that narrower restart path.
• Avoid using full window reload for settings/config changes that only require the Codex backend to re-read config, such as WSL/MCP/app-server runtime changes.

Implementation notes from local inspection

The current singleton design makes a trivial local patch unsafe for exact parity. Killing the singleton codex.exe from a single panel's dispose hook would also kill any other Codex panel using the same CodexMcpConnection. Real parity needs the provider to route MCP requests/responses/notifications through a connection associated with the owning webview/panel/session, or needs an explicit supported app-server restart API with clear UX that it is global to Codex but not global to VS Code.

Expected outcome

A user should be able to reload/restart ChatGPT/Codex inside VS Code without reloading the entire VS Code window and without interrupting other active agents such as Claude Code.