Fix shell omnibox drawer layout

docs/tables_frontend_overhaul_implementation_plan.md

@@ -58,6 +58,7 @@ It is intentionally implementation-focused:
 | 2026-03-21 | P2.6 | Completed | Replaced the dead shell omnibox trigger with a live drawer-backed omnibox foundation that loads critical tables on demand, filters table search results, surfaces pinned and recent table sections from shared state, and exposes slash-command navigation for the core destinations and tooling routes. |
 | 2026-03-21 | P2.7 | Completed | Added shared frontend primitives for app-bar actions, chips, segmented tabs, drawers, inspector sections, and status indicators, wired the shell omnibox trigger onto the new app-bar action primitive, and switched the new pinned-table labels in `Tables` to the shared status-chip primitive so later page work can build on reusable building blocks instead of fresh ad hoc markup. |
 | 2026-03-21 | P2.8 | Completed | Added a shared `TableContextState` service on top of browser storage and the URL serializer, moved the `Tables` page off page-local table selection persistence, and switched diagnostics to the same restore/persist/build-URI flow so table context logic now lives in shared frontend state instead of being reinvented per page. |
+| 2026-03-21 | Post-P2 fix 1 | Completed | Fixed the shell omnibox drawer regression by adding explicit shell offset variables, constraining drawer/body scrolling, and giving the omnibox its own backdrop geometry so the flyout opens within the visible viewport instead of collapsing into invalid top/bottom positioning. |
 
 ### Lessons Learned
 
@@ -85,6 +86,7 @@ It is intentionally implementation-focused:
 - The serializer alone is not the reusable boundary. The maintainable seam is a shared context-state helper that owns restore, persist, normalization, and URI-building conventions while pages keep only workflow-specific selection logic.
 - Primitive extraction lands best when one or two live consumers adopt the new components immediately. That keeps the foundation honest without forcing a broad page rewrite just to validate the abstraction.
 - The omnibox foundation does not need the full final interaction model to be useful. A drawer with real table search, real pinned/recent data, and a small slash-command set is enough to validate the shell surface before Phase 3 builds deeper index and inspector flows on top of it.
+- Shared overlay primitives should not depend on undeclared layout variables. If a drawer needs shell offsets, the shell must define them explicitly and overlay-specific backdrops should be adjustable instead of assuming full-screen dimming is always correct.
 
 ## Target Outcomes