Feature request: reload .github/instructions mid-session (long-running sessions never pick up instruction updates)

Observed behavior

Custom instructions (.github/instructions/*.instructions.md) are loaded once at session start. A long-running session — kept alive across many compactions over days — never sees any later edits to those files. We measured a session that crossed 200+ compaction boundaries over ~2.5 weeks: the instruction content it held stayed at its boot-time version the whole way, while the on-disk files moved dozens of revisions ahead. Compaction/summarization does not re-read the instruction files, so there is currently no way for updated standing instructions to reach an in-flight session at all.

Why it matters

For anyone using instruction files as living, standing guidance (conventions, safety rules, project state), the effective delivery is boot-only. The longer and more productive a session, the staler its standing instructions — the sessions you care most about are the ones guaranteed to be furthest behind. Restarting the session works but discards its accumulated context, which is exactly what long-running sessions exist to keep.

Ask

Any one of these would resolve it:

1. An explicit reload command/verb (e.g. /reload-instructions) that re-reads the instruction files into the live session, or
2. Automatic re-read of instruction files at each compaction boundary (a natural moment, since context is being rebuilt anyway), or
3. A documented statement that instructions are boot-only, so users can design around it deliberately (e.g., scheduled restarts).

Environment

Copilot CLI on Windows, long-lived sessions resumed across days, instruction files under .github/instructions/ in the working directory.

.github/instructions/*.instructions.md 配下のファイルを使って長時間実行される Copilot CLI セッションを再現することから始め、その後、コンパクション前後の指示内容を比較します。初期の指示の読み込みと、コンパクション／要約の動作を追跡します。更新された指示が実行中のセッションに反映されるか、起動時のみ読み込まれる動作が明確に文書化されていれば完了です。