[FEATURE] Allow customization of message right-click context menu

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

Currently, the right-click context menu in the Claude Code desktop app shows a fixed set of options (Copy message, Copy as Markdown, Attach selection as context, Pin as chapter). There is no way to add custom actions.

When reading English responses, I often want to quickly translate a selected word or phrase to another language without leaving the app or increasing the current session's context. A custom context menu entry (e.g., "Translate") would allow this with a single click — similar to how browser extensions like DeepL add translation to the browser's right-click menu.

<img width="1392" height="518" alt="Image" src="https://github.com/user-attachments/assets/adceed9e-9a4a-42d5-95a2-c2e3daca5303" />

Proposed Solution

Allow users to register custom context menu items, similar to how custom slash commands work today (~/.claude/commands/). For example:

• A config entry or command file that defines a label + action to execute on the selected text
• The action could invoke a slash command or call Claude with the selected text as input

Alternatives Considered
Custom slash commands (/translate <text>) work but require manually copying text and add to session context
Third-party tools like PopClip work system-wide but require an additional paid app

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)

Use Case Example

_No response_

Additional Context

_No response_