fix: clean newline paste thingy

ui-tui/src/lib/text.test.ts

@@ -0,0 +1,18 @@
+import { describe, expect, it } from 'vitest'
+
+import { stripTrailingPasteNewlines } from './text.js'
+
+describe('stripTrailingPasteNewlines', () => {
+  it('removes trailing newline runs from pasted text', () => {
+    expect(stripTrailingPasteNewlines('alpha\n')).toBe('alpha')
+    expect(stripTrailingPasteNewlines('alpha\nbeta\n\n')).toBe('alpha\nbeta')
+  })
+
+  it('preserves interior newlines', () => {
+    expect(stripTrailingPasteNewlines('alpha\nbeta\ngamma')).toBe('alpha\nbeta\ngamma')
+  })
+
+  it('preserves newline-only pastes', () => {
+    expect(stripTrailingPasteNewlines('\n\n')).toBe('\n\n')
+  })
+})

ui-tui/src/lib/text.ts

@@ -49,6 +49,8 @@ export const thinkingPreview = (reasoning: string, mode: ThinkingMode, max: numb
   return !text || mode === 'collapsed' ? '' : mode === 'full' ? text : compactPreview(text, max)
 }
 
+export const stripTrailingPasteNewlines = (text: string) => (/[^\n]/.test(text) ? text.replace(/\n+$/, '') : text)
+
 export const toolTrailLabel = (name: string) =>
   name
     .split('_')