[FEATURE] Let me accept the suggested next message shown as input placeholder

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

The input field regularly shows a suggested next message as greyed-out placeholder text (e.g. "Ja, leg die Indizes an sobald die Indexierung durch ist" after Claude asks whether to proceed). It reads like an offer to take, but there is no way to take it: the placeholder is not clickable, and no key inserts it into the input.

So the suggestion is effectively dead weight. Either I retype the whole sentence by hand, or I ignore it and type something short instead. Every time this appears I notice the affordance and then find there is nothing behind it, which is a small but constant friction point.

Proposed Solution

Make the suggestion acceptable with a single gesture:

• A key inserts the placeholder text into the input, the way shell autosuggestions work: Tab, or Right-Arrow / End when the cursor is at the end of an empty input.
• Clicking or tapping the placeholder does the same.
• The text should land in the input as normal editable content, not be submitted immediately, so it can still be adjusted before sending.
• Optionally show a subtle hint such as "Tab to accept" next to the placeholder for the first few occurrences.

Alternative Solutions

Current workaround: retype the sentence, or reply with a short "yes, do that" and rely on the model to resolve the reference from its own previous message. The short reply works fine in practice, but it discards the precise phrasing the suggestion offered, and it leaves the placeholder feeling like decoration rather than a control.

Shell autosuggestion implementations (fish, zsh-autosuggestions) and email smart-compose are the obvious prior art here: greyed-out suggestion + one key to accept.

Priority

High - Significant impact on productivity

Feature Category

Interactive mode (TUI)

Use Case Example

1. Claude finishes a long-running indexing step and asks whether it should create the indexes.
2. The input field shows "Ja, leg die Indizes an sobald die Indexierung durch ist" as placeholder text.
3. I press Tab -> the sentence is inserted into the input as editable text.
4. I press Enter, or edit the sentence first and then send.

Today step 3 is impossible, so the suggestion has to be retyped or abandoned.

Additional Context

Observed in the Claude Code desktop app on Windows 11. (Screenshot of the placeholder can be attached to this issue.)

This is purely about the accept path — the suggestions themselves are already useful and well-targeted.