[FEATURE] Support read-only slash commands in AskUserQuestion input

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When Claude uses the AskUserQuestion tool to prompt for input (commonly during Plan Mode), the free-text field accepts any text. If a user types a slash command (e.g., /cost, /help) into that field, the text is submitted as a literal string answer to the question rather than being intercepted as a command.

Observed behavior: Typing /cost into the AskUserQuestion input submits the string "/cost" as the answer. Claude then interprets it as conversational text. The user must dismiss or answer the question, return to the main prompt, and re-enter the command.

Why this matters: The AskUserQuestion input looks and feels like the main prompt. There is no visual indicator that slash commands are unavailable in this context. Users who habitually type /cost or /help discover the difference only after submission.

This is a minor UX inconsistency, not a blocker. The workaround (answer first, then run the command) is straightforward but unintuitive.

Proposed Solution

Minimal scope (recommended): Support a small set of stateless, read-only slash commands within the AskUserQuestion input:

• /cost / /usage — display session cost/usage info
• /help — show available commands
• /exit — exit the session

When the user submits one of these commands, display its output inline, then re-present the same AskUserQuestion prompt so the user can still answer the original question.

Why only stateless commands: Commands like /compact modify conversation history and interact with the tool_use/tool_result message contract. Executing /compact mid-question could leave an orphaned tool_use without a corresponding tool_result, potentially corrupting conversation state. Stateless commands avoid this entirely because they only render local information and do not alter the message stream.

Namespace disambiguation: Text starting with / that does not match a registered command should be passed through as-is (current behavior), preserving the ability to type answers like /api/v2.

Out of scope: Custom skills, user-defined commands, and state-modifying commands (/compact, /clear, /model) — these require deeper architectural consideration.

Alternative Solutions

1. Visual hint: Display a note in the AskUserQuestion UI: "Slash commands are not available here. Press Escape to return to the main prompt." Zero-risk, addresses discoverability.

1. Escape-to-dismiss: Ensure pressing Escape cleanly returns to the main prompt (where all commands work), sending [User cancelled] as the tool_result. (Related: #27998 reports AskUserQuestion blocking visibility of Claude's response.)

1. Documentation only: Add a note to /help output clarifying that commands are only available at the main prompt. Lowest effort.

Priority

Low

Feature Category

TUI

Use Case Example

Scenario 1: Checking cost mid-plan

1. User is in Plan Mode. Claude presents options via AskUserQuestion: "Which approach would you like?"
2. Before deciding, the user wants to check remaining budget: types /cost.
3. Current: "/cost" is submitted as the answer. Claude responds with confusion.
4. Desired: Cost info is displayed, then the question re-appears.

Scenario 2: Needing help with available commands

1. AskUserQuestion prompts the user during a planning session.
2. User types /help to check available commands.
3. Current: "/help" becomes the answer text.
4. Desired: Help output is shown, question re-appears.

Additional Context

Related issues:

• #18913 — Feature request for async command execution while Claude is busy (same theme: commands should work regardless of UI state)
• #10057 — Slash commands ignored during task execution (closed; same class of problem)
• #16072 — System prompt conflates skills and slash commands (relevant background; this request intentionally excludes skills)
• #27998 — AskUserQuestion popup blocks reading Claude's response (related AskUserQuestion UX)

Note: Claude Code is a closed-source application. The suggestions above are based on observed behavior and may need adjustment based on actual architecture. The "stateless commands only" scope is deliberately conservative to minimize risk.