[FEATURE] First-class steering queue UI: view, delete, and inject queued messages individually

Feature request

When Claude is working on a long task, messages I send are queued and delivered at the next opportunity. Functionally this works, but the queue itself is invisible and unmanageable: once a message is sent, I lose all control over it.

OpenAI's Codex treats the pending-instruction queue as a first-class UI object, and the difference in day-to-day use is significant. In Codex, while the agent is running:

• Every queued follow-up instruction is shown as a visible list item above the input box.
• Each item has a "steer" button to inject that specific message into the current run immediately.
• Each item can be deleted individually before it is consumed.
• The user can see at a glance what the agent is about to receive.

Problem with the current behavior

In Claude Code (desktop app), when I queue several follow-ups during a long turn:

1. I cannot see a clear list of what is still pending.
2. I cannot retract one specific message (e.g. I queued five, the third is now wrong — my only options are to interrupt everything or let it through).
3. I cannot prioritize one queued message over another; delivery order is fixed.
4. Queued messages get merged into a single combined message instead of being handled as separate intents (see #73661).

Proposed behavior

• Render queued messages as a visible, persistent list while a task is running.
• Per-item actions: inject now (steer), delete, and ideally edit before delivery.
• Keep the current "auto-deliver at next tool boundary" as the default so no extra clicks are required for the simple case.

Related issues

• #62877 (closed) — editable queued messages with auto-send lock
• #73661 — process queued messages sequentially instead of merging
• #71726 — desktop app steering parity
• #77010 — queued messages silently lost on session switch

These each cover a slice of the problem; this request is for the umbrella UX: make the steering queue visible and manageable.

Environment

• Claude Code desktop app on Windows 11