Codex App: `/side` sometimes missing from main chat slash command picker

What issue are you seeing?

In the main chat composer, typing /side sometimes does not show the option to open a side chat. Instead, the slash command picker shows No commands even though /side is a valid/expected command in the Codex App workflow.

This prevents creating a side chat from the main channel even when the user is intentionally trying to branch into a side conversation.

What steps can reproduce the bug?

I do not yet have a fully deterministic repro, but the observed flow is:

1. Open Codex Desktop in an existing main chat/thread.
2. Focus the main chat composer.
3. Type /side.
4. Observe that the command picker sometimes shows No commands instead of an action to open a side chat.

What is the expected behavior?

Typing /side in the main chat composer should consistently show the side-chat command/action when side chats are available.

If /side is unavailable in a specific state, the UI should show a clear disabled reason instead of No commands.

Actual behavior

The command picker can show No commands for /side, leaving no visible way to open a side chat from the main composer.

Additional information

I inspected the local openai/codex checkout before filing:

• The open-source TUI slash commands are centralized in codex-rs/tui/src/slash_command.rs and codex-rs/tui/src/bottom_pane/slash_commands.rs.
• A targeted search for /side, side chat, and sidechat in codex-rs, docs, codex-cli, and sdk did not find a side-chat slash command implementation in those open-source TUI paths.
• That suggests this bug is likely in the Codex Desktop/app-shell command registry, command availability gating, or command picker state, rather than in the Rust TUI built-in slash command list.

Related but not exact existing issues found during duplicate search:

• #20977: side chats fail to fork/break after inactivity
• #21583: side chat queued/steer messages route to main chat and closed side chats are lost
• #23974: slash command and skill picker selections in side chat do not apply until side chat is closed
• #20262 / #25233 / #23085: side-chat persistence/expiration/draft behavior

This issue is specifically about the main composer not consistently surfacing the /side command option before a side chat is created.