Copilot in Visual Studio's September update turns Bring Your Own Model on by default, but only inside the new Copilot SDK-based Agent
Bring Your Own Model is now on by default in the IDE, with a breaking change attached. This covers what changed and what you have to redo after updating.
// Key points
- Bring Your Own Model is still in preview and on by default in Community, Professional and Enterprise. It uses your team's preferred models through Copilot or your own deployments, signed in to GitHub or not; providers include Microsoft Foundry, OpenAI, Anthropic and Ollama.
- Breaking change: BYOM now requires the new Agent (Preview), built on the GitHub Copilot SDK-powered harness. The previous Ask and Agent modes no longer support it, and previously configured Ollama models must be re-added after updating.
- The Git agent can take a pull request as context and return a summary with links to its comments and files; it needs your Git provider's MCP servers, with GitHub and Azure DevOps supported.
- NuGet Audit warnings in the Error List gain a fixer that opens Copilot Chat in agent mode to fix vulnerable packages via the NuGet MCP server. The update is on every Copilot plan.
Builder's takeRead next to the 10-25 change that split usage by client: Copilot is handing over the choice of model while pulling the entry point into its own agent harness. Teams wiring their own or local models into Visual Studio should note the current setup before updating and retest in the new Agent afterwards, rather than waiting for developers to find their model gone from Ask mode. Same point as my post on model routing: keep the rules for picking models in your own layer, not only in IDE settings.
// Background · from #Coding agents
Full timeline →- Oct 25 The Copilot usage metrics API now breaks usage out by client, listing requests and tokens from Claude Code, Codex, OpenCode and other tools
- Oct 25 GitHub public monitoring adds triage, continuous validity checks, a REST API and webhooks, so enterprises can go after leaked secrets that still work first
- Oct 25 GitHub merges notifications and Copilot in Microsoft Teams: mention @GitHub in a channel to go from a bug notification to a fix PR, with the old app retiring November 16