[mdaigle]

Description

Add pull request milestone guidance to .github/copilot-instructions.md for all agents, including Agent merge:

• Leave milestone assignment to maintainers unless the user explicitly identifies a backport or specifies the intended milestone; ask rather than infer an unclear milestone.
• Preserve human milestone changes, including removals, unless a later explicit user instruction authorizes a change.
• Report failing milestone checks as maintainer-action blockers rather than moving PRs into open milestones.

This is an instructions-only change with no API, runtime behavior, localization, or compatibility changes.

Issues

No linked issue. Addresses agents overriding human milestone choices to satisfy milestone checks.

Testing

No automated tests were added or modified, and runtime tests were not run because this change only updates agent instructions.

git --no-pager diff --check — passed before commit. Manually inspected the diff to confirm that the guidance exists only in .github/copilot-instructions.md and AGENTS.md remains unchanged.

• Tests added or updated (not applicable; instructions only)
• Public API changes documented (not applicable; no API changes)
• Verified against customer repro (not applicable)
• Ensure no breaking changes introduced

Guidelines

Please review the contribution guidelines before submitting a pull request:

• Contributing
• Code of Conduct
• Best Practices
• Coding Style
• Review Process

[Copilot]

🔵 Needs a closer look

Policy compliance and outstanding reviewer feedback could not be verified from the supplied instruction diff without trusted policy sources or a PR identifier and head SHA.

No open issues 🎉

What changed in this PR

Clarifies agent boundaries for pull request milestones, keeping milestone decisions under maintainer control. This is an instructions-only change with no runtime or API impact.

Changes:

• Requires explicit user direction before agents change milestones and clarification when the intended milestone is unclear.
• Preserves human milestone changes, including removals, unless later explicitly authorized.
• Treats failing milestone checks as maintainer-action blockers, not permission to reassign milestones.

File	Description
.github/​copilot-instructions.md	Adds milestone authorization and preservation rules for all agents, including Agent merge.

_{Review effort: Balanced}