Support multiple workspace folders in the Codex app

Problem

The Codex app currently allows selecting only one project folder per workspace.

My setup separates an AI workspace from a knowledge vault:

parent/
  ai-workspace/      # deliverables, drafts, instruction files, AGENTS.md
  obsidian-vault/    # interlinked Markdown notes used as persistent context

These folders are siblings and cannot be merged. The vault is a long-term knowledge base shared with other tools, while the workspace is a working area for current deliverables and agent-facing instruction files. With a single selected folder, Codex cannot read vault context while producing output in the workspace.

Current Workaround

Codex CLI supports --add-dir and sandbox_workspace_write.writable_roots, but the desktop app has no equivalent UI. Using the CLI for this defeats the purpose of the app for non-terminal workflows.

Requested Behavior

Allow adding multiple folders to a workspace in the Codex app, similar to “Add Folder to Workspace” in VS Code.

Each attached folder should appear as its own root in the UI, with per-folder permission profiles, for example:

• AI workspace: read-write
• Obsidian vault / knowledge vault: read-only by default, optionally writable when explicitly enabled
• Shared scripts or related repos: read-only or read-write depending on the task

AGENTS.md discovery should work per root, so each folder can carry its own local instructions and context conventions.

Use Case

An AGENTS.md in the workspace points to a context file describing the setup. Skills can read from and, when permitted, write to the vault for knowledge capture and recall. Deliverables, drafts, and generated artifacts are saved in the workspace.

This pattern works in comparable tools that support multiple folder mounts, and it is the main blocker to using the same setup in the Codex app.

Related

Related but narrower issue: #26338 tracks parent workspaces containing multiple Git repositories. This request is broader: multiple independent local folders, including non-Git knowledge/context folders, selected directly in the Codex app UI.