Problem

During a comprehensive UI consistency review, several micro-cadence and styling discrepancies were identified across toolbars, borders, and buttons:

1. Arbitrary Toolbar Heights

Toolbars stacked above and below the grid do not follow a unified spatial rhythm:

• Selection Calc Bar: 26px
• ResultsTab Export Row: 28px
• DataGridStagingToolbar: 32px
• DataGridFilterBar: 34px
• DataGridValuePanel Header: 36px
• SqlQueryTabBar / Groupings Header: 40px
• SqliteTableView Header: 48px

Proposed Cadence (8dp system):

• 26px: Compact status footers (DataGridCalcBar)
• 32px: Secondary toolbars (DataGridStagingToolbar, DataGridFilterBar, DataGridValuePanel header)
• 40px: Primary headers and tab bars (SqlQueryTabBar, DataGridGroupingsView header)

2. Inconsistent Border Alpha (Zebra Effect)

When multiple toolbars are simultaneously visible in the workspace, horizontal separator borders use varying opacities:

• ResultsTab: cs.border.withValues(alpha: 0.5)
• DataGridStagingToolbar: cs.border.withValues(alpha: 0.35)
• DataGridGroupingsView: cs.border.withValues(alpha: 0.4) and Divider(alpha: 0.3)
• DataGridFilterBar: cs.border (alpha 1.0)
• SqlQueryTabBar: cs.border (alpha 1.0)

Standard: Use a consistent cs.border.withValues(alpha: 0.35) for internal toolbars/sub-bars and cs.border for major window boundaries.

3. Button Implementation Discrepancies

• In DataGridStagingToolbar, _ToolbarButton is manually constructed from MouseRegion + GestureDetector + AnimatedContainer, bypassing shadcn button styles and accessibility semantics.
• IconButton touch targets differ across adjacent panels:
  • ResultsTab: minWidth: 28, minHeight: 28
  • DataGridValuePanel: minWidth: 24, minHeight: 24
  • DataGridFilterBar: minWidth: 20, minHeight: 20
• DataGridValuePanel uses material.TextButton for Format/Minify instead of shadcn GhostButton or OutlineButton.

Acceptance Criteria

• Toolbar heights adhere to standard 26px / 32px / 40px cadence
• Separator borders across stacked toolbars share consistent opacity
• Compact toolbar IconButtons are standardized to 24x24 targets
• _ToolbarButton in staging toolbar is replaced with or aligned to standard shadcn button tokens