Add searchMessages() method to query inside session history

[Navanit-git]

Summary

Implement a searchMessages() method across all SDK languages to enable
in-session message filtering and search.

Problem

Users currently has to manually filter through all
session events to find specific messages. This is cumbersome for:

• Debugging long conversations
• Finding specific agent responses
• Building audit/search features on top of the SDK

Proposed Solution

Add async searchMessages(query, options) method that:

• Accepts string or regex patterns
• Filters by event type (optional)
• Supports case-sensitive/insensitive search
• Returns filtered SessionEvent[] matching criteria

Example Usage

// TypeScript
const results = await session.searchMessages("authentication");
const assistantMsgs = await session.searchMessages("deploy", { 
  eventType: "assistant.message" 
});

[Anvith433]

I'd like to work on this. 👋

I've opened #2378 with a first implementation for the Node.js/TypeScript SDK — an async searchMessages(query, options?) on CopilotSession supporting string/RegExp queries, optional eventType filtering, and case-sensitivity, with unit tests.

I understand from CONTRIBUTING that feature work should be aligned with the team first and kept in sync across all supported languages, so I'm treating that PR as a concrete starting point for the discussion rather than a finished proposal. If you're open to this feature, I'm happy to extend it to the other SDKs (Python, Go, .NET, Java, Rust) and adjust the API shape/semantics to match your preferences.