fix(tui): keep streaming progress stable during interaction

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

@@ -0,0 +1,28 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+import { getInteractionMode, markScrolling, markTyping, resetInteractionMode } from '../app/interactionMode.js'
+import { SCROLLING_IDLE_MS, TYPING_IDLE_MS } from '../config/timing.js'
+
+describe('interactionMode', () => {
+  afterEach(() => {
+    resetInteractionMode()
+    vi.useRealTimers()
+  })
+
+  it('holds scrolling mode briefly then returns idle', () => {
+    vi.useFakeTimers()
+    markScrolling()
+    expect(getInteractionMode()).toBe('scrolling')
+    vi.advanceTimersByTime(SCROLLING_IDLE_MS)
+    expect(getInteractionMode()).toBe('idle')
+  })
+
+  it('typing takes priority over scrolling', () => {
+    vi.useFakeTimers()
+    markTyping()
+    markScrolling()
+    expect(getInteractionMode()).toBe('typing')
+    vi.advanceTimersByTime(TYPING_IDLE_MS)
+    expect(getInteractionMode()).toBe('idle')
+  })
+})

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

@@ -0,0 +1,53 @@
+import { describe, expect, it, vi } from 'vitest'
+
+import { scrollWithSelectionBy } from '../app/scroll.js'
+
+function makeScroll(overrides: Partial<Record<string, unknown>> = {}) {
+  return {
+    getPendingDelta: vi.fn(() => 0),
+    getScrollHeight: vi.fn(() => 100),
+    getScrollTop: vi.fn(() => 10),
+    getViewportHeight: vi.fn(() => 20),
+    getViewportTop: vi.fn(() => 0),
+    scrollBy: vi.fn(),
+    ...overrides
+  }
+}
+
+describe('scrollWithSelectionBy', () => {
+  it('clamps to the actual remaining scroll distance before calling scrollBy', () => {
+    const s = makeScroll({
+      getScrollHeight: vi.fn(() => 30),
+      getScrollTop: vi.fn(() => 9),
+      getViewportHeight: vi.fn(() => 20)
+    })
+    const selection = {
+      captureScrolledRows: vi.fn(),
+      getState: vi.fn(() => null),
+      shiftAnchor: vi.fn(),
+      shiftSelection: vi.fn()
+    }
+
+    scrollWithSelectionBy(10, { scrollRef: { current: s as never }, selection })
+
+    expect(s.scrollBy).toHaveBeenCalledWith(1)
+  })
+
+  it('does nothing at the edge instead of queueing dead pending deltas', () => {
+    const s = makeScroll({
+      getScrollHeight: vi.fn(() => 30),
+      getScrollTop: vi.fn(() => 10),
+      getViewportHeight: vi.fn(() => 20)
+    })
+    const selection = {
+      captureScrolledRows: vi.fn(),
+      getState: vi.fn(() => null),
+      shiftAnchor: vi.fn(),
+      shiftSelection: vi.fn()
+    }
+
+    scrollWithSelectionBy(10, { scrollRef: { current: s as never }, selection })
+
+    expect(s.scrollBy).not.toHaveBeenCalled()
+  })
+})

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

@@ -0,0 +1,13 @@
+import { describe, expect, it } from 'vitest'
+
+import { shouldSetVirtualClamp } from '../hooks/useVirtualHistory.js'
+
+describe('virtual history clamp bounds', () => {
+  it('does not clamp sticky live tail content', () => {
+    expect(shouldSetVirtualClamp({ itemCount: 20, sticky: true, viewportHeight: 10 })).toBe(false)
+  })
+
+  it('sets clamp bounds after manual scroll breaks sticky mode', () => {
+    expect(shouldSetVirtualClamp({ itemCount: 20, sticky: false, viewportHeight: 10 })).toBe(true)
+  })
+})