fix(tui): trim whitespace-only selection chrome

- clamp selection highlight to real row content so blank drag margins do not render or copy
- keep successful copy actions quiet while preserving usage and failure feedback

ui-tui/packages/hermes-ink/src/ink/selection.test.ts

@@ -0,0 +1,57 @@
+import { describe, expect, it } from 'vitest'
+
+import { cellAt, CellWidth, CharPool, createScreen, HyperlinkPool, setCellAt, StylePool } from './screen.js'
+import {
+  applySelectionOverlay,
+  createSelectionState,
+  getSelectedText,
+  startSelection,
+  updateSelection
+} from './selection.js'
+
+const screenWithText = () => {
+  const styles = new StylePool()
+  const screen = createScreen(10, 3, styles, new CharPool(), new HyperlinkPool())
+
+  setCellAt(screen, 2, 1, { char: 'h', hyperlink: undefined, styleId: screen.emptyStyleId, width: CellWidth.Narrow })
+  setCellAt(screen, 3, 1, { char: 'i', hyperlink: undefined, styleId: screen.emptyStyleId, width: CellWidth.Narrow })
+
+  return { screen, styles }
+}
+
+describe('selection whitespace handling', () => {
+  it('does not copy whitespace-only selections', () => {
+    const { screen } = screenWithText()
+    const selection = createSelectionState()
+
+    startSelection(selection, 0, 0)
+    updateSelection(selection, 9, 0)
+
+    expect(getSelectedText(selection, screen)).toBe('')
+  })
+
+  it('trims outer drag padding while preserving selected content', () => {
+    const { screen } = screenWithText()
+    const selection = createSelectionState()
+
+    startSelection(selection, 0, 1)
+    updateSelection(selection, 9, 1)
+
+    expect(getSelectedText(selection, screen)).toBe('hi')
+  })
+
+  it('does not paint selection background on leading/trailing empty cells or empty rows', () => {
+    const { screen, styles } = screenWithText()
+    const selection = createSelectionState()
+
+    startSelection(selection, 0, 0)
+    updateSelection(selection, 9, 2)
+    applySelectionOverlay(screen, selection, styles)
+
+    expect(cellAt(screen, 0, 0)?.styleId).toBe(screen.emptyStyleId)
+    expect(cellAt(screen, 0, 1)?.styleId).toBe(screen.emptyStyleId)
+    expect(cellAt(screen, 2, 1)?.styleId).not.toBe(screen.emptyStyleId)
+    expect(cellAt(screen, 4, 1)?.styleId).toBe(screen.emptyStyleId)
+    expect(cellAt(screen, 0, 2)?.styleId).toBe(screen.emptyStyleId)
+  })
+})