CODEX: allow rules overlay in writable sandbox

[davidomil]

Change Contract

Change-Type:

AI-Run-ID:

Base-SHA:

Behavior

Describe the user-visible or operational behavior changed by this pull request.

Architecture

• Owner and production seam:
• Existing anchors followed:
• Cross-boundary contracts affected:

Proof

• Revert-failing test:
• Negative and failure cases:
• Commands executed:
• Browser screenshots or artifacts, when visible behavior changed:

Independent Review

• Plan review artifact:
• Implementation review artifact:
• Unresolved findings: none

Checklist

• The changed paths match the declared type and architecture owner.
• Verification ran without modifying the worktree.
• Review evidence is bound to this exact head SHA.
• Governance or security-sensitive changes have maintainer approval.