MCP tools/list_changed notification: updated tools not visible to the model until the next user turn

### Describe the bug

When an MCP server emits a notifications/tools/list_changed notification mid-turn, the updated tool list is not visible to the model until the next user turn.

**Repro / observed behavior**
User sends a message; the agent loop starts.
The model calls a tool on an MCP server; that tool causes the server to add/remove a tool and emit notifications/tools/list_changed.
The agent loop continues with another model iteration in the same turn.
The model still sees the old tool list. Newly added tools are not callable; removed tools are still advertised.
On the next user message, the new tool list finally becomes visible.

### Affected version

1.0.41-1

### Steps to reproduce the behavior

User sends a message; the agent loop starts.
The model calls a tool on an MCP server; that tool causes the server to add/remove a tool and emit notifications/tools/list_changed.
The agent loop continues with another model iteration in the same turn.
The model still sees the old tool list. Newly added tools are not callable; removed tools are still advertised.
On the next user message, the new tool list finally becomes visible.

### Expected behavior

The model can see the new newly added tools without requiring another user->model conversation turn.
This is required in order to support MCP servers that implement progressive disclosure of tools server-side.

### Additional context

_No response_

Start by reproducing the described agent loop with an MCP server whose tool call emits notifications/tools/list_changed, then trace where the tool list is supplied on the next model iteration. Done means newly added tools are visible and removed tools are no longer advertised within the same user turn, without requiring another user message.

索引モデルが issue の本文から書いたものです。