Fixes#43165
## Problem
MCP prompts were only available in text threads, not agent threads.
Users with MCP servers that expose prompts couldn't use them in the main
agent panel.
## Solution
Added MCP prompt support to agent threads by:
- Creating `ContextServerPromptRegistry` to track MCP prompts from
context servers
- Subscribing to context server events to reload prompts when MCP
servers start/stop
- Converting MCP prompts to available commands that appear in the slash
command menu
- Integrating prompt expansion into the agent message flow
## Testing
Tested with a custom MCP server exposing `explain-code` and
`write-tests` prompts. Prompts now appear in the `/` slash command menu
in agent threads.
Release Notes:
- Added MCP prompt support to agent threads. Prompts from MCP servers
now appear in the slash command menu when typing `/` in agent threads.
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Co-authored-by: Agus Zubiaga <agus@zed.dev>
4896f477e2