doctrine: publish harvested rules

plugins/design-doctrine/rules/interaction/ddr_130.md

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+---
+id: ddr_130
+kind: guideline
+strength: default
+confidence: low
+status: active
+domain: interaction.menus
+products: ["bb"]
+activities: ["build","review"]
+artifacts: ["component"]
+surfaces: ["mobile","menu","drawer"]
+relations: []
+supporting_episodes: 1
+challenging_episodes: 0
+updated: 2026-10-18
+---
+
+# Mobile submenus replace in place, never stack
+
+On mobile, opening a nested menu should replace the current menu contents inside the same drawer (with a Back control), reusing the existing mobile menu pattern, rather than layering a second menu over the first.
+
+## Why
+
+Overlapping nested menus on small screens are confusing and visually broken; one drawer with page replacement keeps a single focus and a clear way back.
+
+## Prefer
+
+- One responsive drawer whose contents swap to the selected submenu
+- A Back row at the top to return to the parent menu
+- Reusing the established mobile menu pattern
+
+## Avoid
+
+- Opening a second popover or sheet on top of an open mobile menu
+- Introducing a new one-off menu mechanism for a single nested case
+
+## Use when
+
+- mobile nested menu
+- narrow-width submenu
+
+## Do not use when
+
+- desktop cascades
+
+## Evidence
+
+- User reported nested mobile More menus overlapping instead of replacing each other and asked that the fix reuse existing mobile menu patterns.
+
+## Check
+
+- At mobile width, opening a submenu leaves exactly one menu surface visible
+- A Back control returns to the parent menu contents