feat(tui): add unread tab glow (#39428)

packages/tui/src/component/session-tabs.tsx

@@ -170,7 +170,9 @@ export function SessionTabs() {
                 enabled={config.animations ?? true}
                 active={status().busy}
                 complete={status().complete}
+                glow={status().unread === "activity" && !status().busy && !selected() && !status().attention}
                 color={pulseColor()}
+                glowColor={accent()}
                 completionColor={accent()}
                 backgroundColor={pulseBackground()}
               />

packages/tui/src/component/tab-pulse.tsx

@@ -6,7 +6,9 @@ type TabPulseOptions = RenderableOptions<TabPulseRenderable> & {
   enabled?: boolean
   active?: boolean
   complete?: boolean
+  glow?: boolean
   color?: RGBA
+  glowColor?: RGBA
   completionColor?: RGBA
   backgroundColor?: RGBA
 }
@@ -19,6 +21,8 @@ const RUN_TAIL = 18
 const RUN_FADE_OUT = 500
 const COMPLETION_DURATION = 900
 const COMPLETION_ATTACK = 0.16
+const GLOW_TAIL = 12
+const GLOW_OPACITY = 0.16
 const intensityAt = (index: number, front: number, head: number, tail: number) => {
   const distance = front - index
   return distance < 0 ? smootherstep(clamp(1 + distance / head)) : smootherstep(clamp(1 - distance / tail))
@@ -33,11 +37,17 @@ export const completionPulseOpacity = (progress: number) =>
   progress < COMPLETION_ATTACK
     ? smootherstep(clamp(progress / COMPLETION_ATTACK))
     : 1 - smootherstep(clamp((progress - COMPLETION_ATTACK) / (1 - COMPLETION_ATTACK)))
+export const unreadGlowIntensity = (index: number, width: number) => {
+  const tail = Math.min(GLOW_TAIL, Math.max(1, width - 2))
+  return smootherstep(clamp(1 - Math.max(0, index - 1) / tail))
+}
 class TabPulseRenderable extends Renderable {
   private _enabled: boolean
   private _active: boolean
   private _complete: boolean
+  private _glow: boolean
   private _color: RGBA
+  private _glowColor: RGBA
   private _completionColor: RGBA
   private _backgroundColor: RGBA
   private clock = 0
@@ -52,7 +62,9 @@ class TabPulseRenderable extends Renderable {
     this._enabled = enabled
     this._active = active
     this._complete = options.complete ?? false
+    this._glow = options.glow ?? false
     this._color = options.color ?? RGBA.defaultForeground()
+    this._glowColor = options.glowColor ?? this._color
     this._completionColor = options.completionColor ?? this._color
     this._backgroundColor = options.backgroundColor ?? RGBA.defaultBackground()
   }
@@ -103,12 +115,24 @@ class TabPulseRenderable extends Renderable {
     this.requestRender()
   }
 
+  set glow(value: boolean) {
+    if (value === this._glow) return
+    this._glow = value
+    this.requestRender()
+  }
+
   set color(value: RGBA) {
     if (value.equals(this._color)) return
     this._color = value
     this.requestRender()
   }
 
+  set glowColor(value: RGBA) {
+    if (value.equals(this._glowColor)) return
+    this._glowColor = value
+    this.requestRender()
+  }
+
   set completionColor(value: RGBA) {
     if (value.equals(this._completionColor)) return
     this._completionColor = value
@@ -144,15 +168,19 @@ class TabPulseRenderable extends Renderable {
   }
 
   protected override renderSelf(buffer: OptimizedBuffer): void {
-    if (!this.visible || this.isDestroyed || !this._enabled || this.width <= 0) return
-    const runningOpacity = this._active
-      ? 1
-      : this.fadeClock === undefined
-        ? 0
-        : 1 - smootherstep(clamp(this.fadeClock / RUN_FADE_OUT))
+    if (!this.visible || this.isDestroyed || this.width <= 0) return
+    const runningOpacity = !this._enabled
+      ? 0
+      : this._active
+        ? 1
+        : this.fadeClock === undefined
+          ? 0
+          : 1 - smootherstep(clamp(this.fadeClock / RUN_FADE_OUT))
     const completionOpacity =
-      this.completionClock === undefined ? 0 : completionPulseOpacity(this.completionClock / COMPLETION_DURATION)
-    if (runningOpacity === 0 && completionOpacity === 0) return
+      !this._enabled || this.completionClock === undefined
+        ? 0
+        : completionPulseOpacity(this.completionClock / COMPLETION_DURATION)
+    if (!this._glow && runningOpacity === 0 && completionOpacity === 0) return
     const progress = (this.clock % RUN_DURATION) / RUN_DURATION
     const start = -RUN_HEAD
     const end = this.width - 1 + RUN_TAIL
@@ -163,7 +191,10 @@ class TabPulseRenderable extends Renderable {
         intensityAt(index, front, RUN_HEAD, RUN_TAIL),
         intensityAt(index, secondFront, RUN_HEAD, RUN_TAIL),
       )
-      const running = tint(this._backgroundColor, this._color, intensity * 0.14 * runningOpacity)
+      const background = this._glow
+        ? tint(this._backgroundColor, this._glowColor, unreadGlowIntensity(index, this.width) * GLOW_OPACITY)
+        : this._backgroundColor
+      const running = tint(background, this._color, intensity * 0.14 * runningOpacity)
       buffer.setCell(
         this.screenX + index,
         this.screenY,
@@ -187,7 +218,9 @@ export function TabPulse(props: {
   enabled?: boolean
   active: boolean
   complete?: boolean
+  glow?: boolean
   color: RGBA
+  glowColor?: RGBA
   completionColor?: RGBA
   backgroundColor: RGBA
 }) {
@@ -199,7 +232,9 @@ export function TabPulse(props: {
       enabled={props.enabled ?? true}
       active={props.active}
       complete={props.complete ?? false}
+      glow={props.glow ?? false}
       color={props.color}
+      glowColor={props.glowColor ?? props.color}
       completionColor={props.completionColor ?? props.color}
       backgroundColor={props.backgroundColor}
     />

packages/tui/test/component/tab-pulse.test.ts

@@ -1,5 +1,5 @@
 import { expect, test } from "bun:test"
-import { completionPulseOpacity } from "../../src/component/tab-pulse"
+import { completionPulseOpacity, unreadGlowIntensity } from "../../src/component/tab-pulse"
 
 test("completion pulse rises quickly and fades over the remaining duration", () => {
   expect(completionPulseOpacity(0)).toBe(0)
@@ -8,3 +8,19 @@ test("completion pulse rises quickly and fades over the remaining duration", ()
   expect(completionPulseOpacity(0.58)).toBeCloseTo(0.5)
   expect(completionPulseOpacity(1)).toBe(0)
 })
+
+test("unread glow peaks behind the tab number and fades to the normal background", () => {
+  const intensities = Array.from({ length: 22 }, (_, index) => unreadGlowIntensity(index, 22))
+
+  expect(intensities[0]).toBe(1)
+  expect(intensities[1]).toBe(1)
+  expect(intensities[2]).toBeLessThan(1)
+  expect(intensities.slice(1)).toEqual(intensities.slice(1).sort((a, b) => b - a))
+  expect(intensities[13]).toBe(0)
+  expect(intensities.at(-1)).toBe(0)
+})
+
+test("unread glow reaches the normal background on compact tabs", () => {
+  expect(unreadGlowIntensity(0, 8)).toBe(1)
+  expect(unreadGlowIntensity(7, 8)).toBe(0)
+})