chore(tui): /clean recent perf work — KISS/DRY pass

24 files, -319 LoC. Behaviour preserved, 369/369 tests green.

- hermes-ink caches: shared lruEvict helper for the four parallel LRU
  caches (stringWidth, wrapText, sliceAnsi, lineWidth); touch-on-read
  stays inlined per cache; tightened output.ts skip-slice fast path.
- wheelAccel: trimmed provenance header, collapsed env parsing, ternary
  dispatch in computeWheelStep.
- perfPane: folded ensureLogDir into once-flag, spread-with-overrides
  for fastPath/phases instead of full rebuilds.
- env: extracted truthy() (used 4×).
- virtualHeights: collapsed user/diff/slash height bumps; trail+todos
  estimate.
- useInputHandlers: scrollIdleTimer cleanup on unmount, ?? undefined
  shorthand.
- useMainApp: dropped dead liveTailVisible IIFE and liveProgress
  indirection.
- appLayout, markdown, messageLine, entry: vertical rhythm, dropped
  narration comments, inlined one-shot vars.
- fix: empty catch blocks → /* best-effort */ for no-empty lint.

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

@@ -12,38 +12,29 @@ describe('wheelAccel — native path', () => {
   it('same-direction fast events ramp mult (window-mode)', () => {
     const s = initWheelAccel(false, 1)
 
-    // First click establishes dir. Subsequent clicks inside the 40ms
-    // window ramp by +0.3 each (capped at 6).
     computeWheelStep(s, 1, 1000)
     computeWheelStep(s, 1, 1020)
     computeWheelStep(s, 1, 1040)
-    const fourth = computeWheelStep(s, 1, 1060)
 
-    // After 3 window events: mult starts at 1 → stays 1 on first ramp
-    // (first event just sets baseline), then +0.3 × 3 = 1.9 → floor=1.
-    // The key property: doesn't shrink below base.
-    expect(fourth).toBeGreaterThanOrEqual(1)
+    // Key property: doesn't shrink below base.
+    expect(computeWheelStep(s, 1, 1060)).toBeGreaterThanOrEqual(1)
   })
 
   it('gap beyond window resets mult to base', () => {
     const s = initWheelAccel(false, 1)
 
-    // Ramp up
     for (let t = 1000; t < 1100; t += 20) {
       computeWheelStep(s, 1, t)
     }
 
-    // Long pause, then click
-    const afterPause = computeWheelStep(s, 1, 2000)
-
-    expect(afterPause).toBe(1)
+    expect(computeWheelStep(s, 1, 2000)).toBe(1)
   })
 
   it('direction flip defers one event for bounce detection', () => {
     const s = initWheelAccel(false, 1)
 
     computeWheelStep(s, 1, 1000)
-    // Flip — should defer
+
     expect(computeWheelStep(s, -1, 1050)).toBe(0)
   })
 
@@ -51,9 +42,7 @@ describe('wheelAccel — native path', () => {
     const s = initWheelAccel(false, 1)
 
     computeWheelStep(s, 1, 1000)
-    // Flip (deferred)
     computeWheelStep(s, -1, 1050)
-    // Flip BACK within 200ms → bounce confirmed → wheelMode engaged
     computeWheelStep(s, 1, 1100)
 
     expect(s.wheelMode).toBe(true)
@@ -63,8 +52,7 @@ describe('wheelAccel — native path', () => {
     const s = initWheelAccel(false, 1)
 
     computeWheelStep(s, 1, 1000)
-    computeWheelStep(s, -1, 1050) // defer
-    // Flip-back arrives 300ms later → too late → real reversal
+    computeWheelStep(s, -1, 1050)
     computeWheelStep(s, 1, 1400)
 
     expect(s.wheelMode).toBe(false)
@@ -76,12 +64,9 @@ describe('wheelAccel — native path', () => {
     s.dir = 1
     s.time = 1000
 
-    // 5 bursts <5ms apart (trackpad flick)
-    computeWheelStep(s, 1, 1002)
-    computeWheelStep(s, 1, 1004)
-    computeWheelStep(s, 1, 1006)
-    computeWheelStep(s, 1, 1008)
-    computeWheelStep(s, 1, 1010)
+    for (let t = 1002; t <= 1010; t += 2) {
+      computeWheelStep(s, 1, t)
+    }
 
     expect(s.wheelMode).toBe(false)
   })
@@ -92,7 +77,7 @@ describe('wheelAccel — native path', () => {
     s.dir = 1
     s.time = 1000
 
-    computeWheelStep(s, 1, 3000) // 2 second gap
+    computeWheelStep(s, 1, 3000)
 
     expect(s.wheelMode).toBe(false)
   })
@@ -102,34 +87,23 @@ describe('wheelAccel — xterm.js path', () => {
   it('first click returns 2 after long idle', () => {
     const s = initWheelAccel(true, 1)
 
-    // First event — "sameDir && gap > WHEEL_DECAY_IDLE_MS" triggers
-    // reset-to-2 branch since dir starts at 0 and 0 !== 1.
-    const n = computeWheelStep(s, 1, 1000)
-
-    expect(n).toBeGreaterThanOrEqual(1)
+    expect(computeWheelStep(s, 1, 1000)).toBeGreaterThanOrEqual(1)
   })
 
   it('sub-5ms burst returns 1 (same-direction, same-batch)', () => {
     const s = initWheelAccel(true, 1)
 
     computeWheelStep(s, 1, 1000)
-    const burst = computeWheelStep(s, 1, 1002)
 
-    expect(burst).toBe(1)
+    expect(computeWheelStep(s, 1, 1002)).toBe(1)
   })
 
   it('slow steady scroll stays in precision range', () => {
     const s = initWheelAccel(true, 1)
 
-    // Simulated 30Hz sustained scroll: 33ms gap
-    const results: number[] = []
-
     for (let t = 1000; t < 2000; t += 33) {
-      results.push(computeWheelStep(s, 1, t))
-    }
+      const r = computeWheelStep(s, 1, t)
 
-    // Every event should produce 1-6 rows.  No runaway.
-    for (const r of results) {
       expect(r).toBeGreaterThanOrEqual(1)
       expect(r).toBeLessThanOrEqual(6)
     }
@@ -138,27 +112,22 @@ describe('wheelAccel — xterm.js path', () => {
   it('direction reversal resets mult', () => {
     const s = initWheelAccel(true, 1)
 
-    // Ramp up
     for (let t = 1000; t < 1100; t += 20) {
       computeWheelStep(s, 1, t)
     }
+
     const beforeFlip = s.mult
 
-    // Flip
     computeWheelStep(s, -1, 1200)
 
     expect(s.mult).toBeLessThanOrEqual(beforeFlip)
-    // Reset branch sets mult=2
     expect(s.mult).toBe(2)
   })
 
   it('frac stays in [0,1) across events', () => {
     const s = initWheelAccel(true, 1)
 
-    // frac must never go negative or reach 1.0 — that's the correctness
-    // invariant of the fractional carry.  Whether a specific series of
-    // inputs produces a nonzero frac depends on tuning constants; just
-    // check the bound is maintained across a realistic scroll pattern.
+    // Correctness invariant of fractional carry: never negative, never reaches 1.
     for (let t = 1000; t < 1200; t += 30) {
       computeWheelStep(s, 1, t)