fix(tui): keep status rule one-line in skinny terminals

Clamp and truncate the cwd/branch segment so narrow status bars cannot wrap into the composer input row.

ui-tui/src/__tests__/statusRule.test.ts

@@ -0,0 +1,25 @@
+import { describe, expect, it } from 'vitest'
+
+import { statusRuleWidths } from '../components/appChrome.js'
+
+describe('statusRuleWidths', () => {
+  it('keeps the status rule within the terminal width', () => {
+    for (const cols of [8, 12, 20, 40, 100]) {
+      const widths = statusRuleWidths(cols, '~/src/hermes-agent/main (some-long-branch-name)')
+
+      expect(widths.leftWidth + widths.separatorWidth + widths.rightWidth).toBeLessThanOrEqual(cols)
+      expect(widths.leftWidth).toBeGreaterThan(0)
+    }
+  })
+
+  it('truncates the cwd segment before it can wrap in skinny terminals', () => {
+    const widths = statusRuleWidths(24, '~/src/hermes-agent/main (bb/some-extremely-long-branch)')
+
+    expect(widths.rightWidth).toBeLessThan('~/src/hermes-agent/main (bb/some-extremely-long-branch)'.length)
+    expect(widths.leftWidth).toBeGreaterThanOrEqual(8)
+  })
+
+  it('omits the cwd segment when there is no room for it', () => {
+    expect(statusRuleWidths(2, 'abcdef')).toEqual({ leftWidth: 1, rightWidth: 0, separatorWidth: 1 })
+  })
+})