Add process for proposals

CONTRIBUTING.md

@@ -14,11 +14,72 @@ contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any additio
 
 ## How to Contribute
 
-1. Fork the repository
-2. Create a feature branch (`git checkout -b my-feature`)
-3. Make your changes
-4. Run tests and ensure the build passes
-5. Submit a pull request
+This repository accepts pull requests, but not every type of change should start as a pull request.
+
+### Changes That Usually Do Not Need Prior Approval
+
+Small, scoped pull requests are generally welcome without prior discussion when they:
+
+- Fix a clear bug
+- Correct typos, broken links, or other documentation issues
+- Add or improve tests for existing behavior
+- Make low-risk maintenance changes that do not change product direction, architecture, or user experience
+
+These changes should still be focused, easy to review, and aligned with the existing codebase.
+
+### Changes That Require Prior Approval
+
+Please do not open a pull request first for changes such as:
+
+- New features or user-visible capabilities
+- Large refactors or architectural changes
+- Changes to public behavior, workflows, or UI patterns
+- Significant dependency changes
+- Broad performance, telemetry, or security-related changes that affect product direction
+
+These kinds of changes need review and guidance from the Microsoft team responsible for the product roadmap and design direction.
+
+### Proposal First for Larger Changes
+
+If you want to propose a new feature or substantial change, start a GitHub Discussion in the `Ideas` category instead of opening a pull request immediately.
+
+Your proposal should briefly cover:
+
+- The problem you are trying to solve
+- Why the current behavior is insufficient
+- The user impact and expected benefit
+- A rough implementation approach, if relevant
+- Alternatives you considered
+
+When you believe the discussion is ready for formal consideration, add the `design review` label. That label means a design review is requested. It does not mean the proposal has been approved.
+
+The team may:
+
+- Approve the proposal
+- Decline the proposal
+- Request changes to the scope or design
+- Meet with the author to refine the design
+- Decide to implement it internally
+- Mark it as open for a community contribution
+
+When a design is under review a corresponding issue will be opened for it that will track the proposal's progress. 
+The issue may also revise the proposal or add detail for implementation.
+
+Only after that process has resulted in an "open for contribution" status, should a pull request be opened.
+
+### Pull Request Process
+
+1. Fork the repository.
+2. If the change is more than a small bug fix or documentation update, open a GitHub Discussion in `Ideas` first and wait for guidance.
+3. If you are proposing a larger change, use the `design review` label when you are requesting formal design consideration.
+4. If the design is accepted, wait for a member of the Microsoft design team to create the corresponding GitHub Issue for implementation tracking.
+5. Create a branch for the approved or clearly scoped change.
+6. Make the smallest change that fully addresses the issue.
+7. Run relevant tests and ensure the build passes.
+8. Update documentation when behavior or workflows change.
+9. Submit a pull request with a clear description of the problem, approach, and validation.
+
+If a pull request arrives without prior discussion for a change that needs design or roadmap approval, it may be closed and redirected to Discussions.
 
 ## Development Setup
 
@@ -80,3 +141,4 @@ When reporting a bug, please include:
 - Follow existing code style and conventions
 - Update documentation if needed
 - Ensure the build passes before submitting
+- Link the relevant GitHub Discussion when prior approval was required