VS Code extension: add Desktop-level dictation, cross-thread messaging, and agent orchestration

Summary

Make the Codex VS Code extension a first-class Codex client, so code-heavy work does not require switching to Codex Desktop for dictation, thread coordination, or agent management.

Requested capabilities

• Dictation: microphone input in the composer, with a configurable keyboard shortcut and a non-hold-to-talk option where supported.
• Cross-thread access: search, read, resume, and send messages to existing Codex threads, including Desktop-created threads in the same account/project state.
• Thread coordination: inspect activity/status, follow results, and route a question to another thread without manually copying a transcript.
• Agent management: inspect the subagent roster and spawn, reuse, steer, wait for, or stop agents from the VS Code surface.
• Capability transparency: show the active project/environment, tools, and permissions so reopening a thread does not silently lose capabilities.

Why this matters

VS Code has the code-navigation, LSP, editor, and diff-review advantages. Codex Desktop has dictation, long-running thread coordination, and agent/thread messaging. Today users must choose between these surfaces or attempt fragile cross-client thread reuse.

The App Server already exposes thread and streamed-agent primitives, so this appears primarily to be a client/UI parity gap.

Safety and ownership

This does not require two clients to mutate the same thread concurrently. The extension could keep an explicit owner/follower model and route requests through the owner, or clearly show when a thread is active elsewhere and offer a supported attach/hand-off operation instead of an opaque “close it in another application” error.

Acceptance examples

1. Start a thread in Desktop, open it in VS Code, dictate a prompt, and continue it from the editor.
2. From VS Code, search for an existing Desktop thread and send a follow-up to it.
3. Ask a context-rich thread to investigate a question while the VS Code thread continues implementation.
4. View and manage the same subagent activity that is visible in Desktop.
5. If direct shared ownership is unsafe, provide an explicit supported hand-off or routing workflow with a clear owner and synchronized history.

Related reports

• #30006 — Desktop-created threads could sync with VS Code, but discovery was asymmetric.
• #32466 — opening a thread in VS Code could force Desktop to catch up on live updates.
• #25914 — missing documented attach/discovery contract for an active Desktop thread.
• #37856 — stale thread ownership blocks VS Code with “open in another application.”
• #38629 — cross-client ownership race can produce concurrent turns.
• #37036 — tool capabilities can differ after reopening project-backed threads.