Add scroll acceleration support to TUI (#4289)

5 files changed, 61 insertions, 5 deletions

diff --git a/packages/opencode/src/cli/cmd/tui/routes/session/index.tsx b/packages/opencode/src/cli/cmd/tui/routes/session/index.tsx
index 4c3dd96ff..e3d199ee4 100644
--- a/packages/opencode/src/cli/cmd/tui/routes/session/index.tsx
+++ b/packages/opencode/src/cli/cmd/tui/routes/session/index.tsx
@@ -17,7 +17,14 @@ import { useRoute, useRouteData } from "@tui/context/route"
 import { useSync } from "@tui/context/sync"
 import { SplitBorder } from "@tui/component/border"
 import { useTheme } from "@tui/context/theme"
-import { BoxRenderable, ScrollBoxRenderable, TextAttributes, addDefaultParsers } from "@opentui/core"
+import {
+  BoxRenderable,
+  ScrollBoxRenderable,
+  TextAttributes,
+  addDefaultParsers,
+  MacOSScrollAccel,
+  type ScrollAcceleration,
+} from "@opentui/core"
 import { Prompt, type PromptRef } from "@tui/component/prompt"
 import type { AssistantMessage, Part, ToolPart, UserMessage, TextPart, ReasoningPart } from "@opencode-ai/sdk"
 import { useLocal } from "@tui/context/local"
@@ -62,6 +69,16 @@ import { LSP } from "@/lsp/index.ts"
 
 addDefaultParsers(parsers.parsers)
 
+class CustomSpeedScroll implements ScrollAcceleration {
+  constructor(private speed: number) {}
+
+  tick(_now?: number): number {
+    return this.speed
+  }
+
+  reset(): void {}
+}
+
 const context = createContext<{
   width: number
   conceal: () => boolean
@@ -95,6 +112,17 @@ export function Session() {
   const sidebarVisible = createMemo(() => sidebar() === "show" || (sidebar() === "auto" && wide()))
   const contentWidth = createMemo(() => dimensions().width - (sidebarVisible() ? 42 : 0) - 4)
 
+  const scrollAcceleration = createMemo(() => {
+    const tui = sync.data.config.tui
+    if (tui?.scroll_acceleration?.enabled) {
+      return new MacOSScrollAccel()
+    }
+    if (tui?.scroll_speed) {
+      return new CustomSpeedScroll(tui.scroll_speed)
+    }
+    return undefined
+  })
+
   createEffect(async () => {
     await sync.session
       .sync(route.sessionID)
@@ -684,6 +712,7 @@ export function Session() {
               stickyScroll={true}
               stickyStart="bottom"
               flexGrow={1}
+              scrollAcceleration={scrollAcceleration()}
             >
               <For each={messages()}>
                 {(message, index) => (
diff --git a/packages/opencode/src/config/config.ts b/packages/opencode/src/config/config.ts
index e6bed238f..3ca8c25de 100644
--- a/packages/opencode/src/config/config.ts
+++ b/packages/opencode/src/config/config.ts
@@ -437,7 +437,13 @@ export namespace Config {
     })
 
   export const TUI = z.object({
-    scroll_speed: z.number().min(1).optional().default(2).describe("TUI scroll speed"),
+    scroll_speed: z.number().min(1).optional().default(1).describe("TUI scroll speed"),
+    scroll_acceleration: z
+      .object({
+        enabled: z.boolean().describe("Enable scroll acceleration"),
+      })
+      .optional()
+      .describe("Scroll acceleration settings"),
   })
 
   export const Layout = z.enum(["auto", "stretch"]).meta({
diff --git a/packages/sdk/js/src/gen/types.gen.ts b/packages/sdk/js/src/gen/types.gen.ts
index 3e64fc9a0..1d90fe106 100644
--- a/packages/sdk/js/src/gen/types.gen.ts
+++ b/packages/sdk/js/src/gen/types.gen.ts
@@ -301,6 +301,15 @@ export type Config = {
      * TUI scroll speed
      */
     scroll_speed?: number
+    /**
+     * Scroll acceleration settings
+     */
+    scroll_acceleration?: {
+      /**
+       * Enable scroll acceleration
+       */
+      enabled: boolean
+    }
   }
   /**
    * Command configuration, see https://opencode.ai/docs/commands
diff --git a/packages/web/src/content/docs/config.mdx b/packages/web/src/content/docs/config.mdx
index c02edd2ff..a27acc779 100644
--- a/packages/web/src/content/docs/config.mdx
+++ b/packages/web/src/content/docs/config.mdx
@@ -93,11 +93,19 @@ You can configure TUI-specific settings through the `tui` option.
 {
   "$schema": "https://opencode.ai/config.json",
   "tui": {
-    "scroll_speed": 3
+    "scroll_speed": 3,
+    "scroll_acceleration": {
+      "enabled": true
+    }
   }
 }
 ```
 
+Available options:
+
+- `scroll_acceleration.enabled` - Enable macOS-style scroll acceleration. **Takes precedence over `scroll_speed`.**
+- `scroll_speed` - Custom scroll speed multiplier (default: `1`, minimum: `1`). Ignored if `scroll_acceleration.enabled` is `true`.
+
 [Learn more about using the TUI here](/docs/tui).
 
 ---
diff --git a/packages/web/src/content/docs/tui.mdx b/packages/web/src/content/docs/tui.mdx
index 4dd7608be..f50409c41 100644
--- a/packages/web/src/content/docs/tui.mdx
+++ b/packages/web/src/content/docs/tui.mdx
@@ -336,11 +336,15 @@ You can customize TUI behavior through your OpenCode config file.
 {
   "$schema": "https://opencode.ai/config.json",
   "tui": {
-    "scroll_speed": 3
+    "scroll_speed": 3,
+    "scroll_acceleration": {
+      "enabled": true
+    }
   }
 }
 ```
 
 ### Options
 
-- `scroll_speed` - Controls how fast the TUI scrolls when using scroll commands (default: `2`, minimum: `1`)
+- `scroll_acceleration` - Enable macOS-style scroll acceleration for smooth, natural scrolling. When enabled, scroll speed increases with rapid scrolling gestures and stays precise for slower movements. **This setting takes precedence over `scroll_speed` and overrides it when enabled.**
+- `scroll_speed` - Controls how fast the TUI scrolls when using scroll commands (default: `1`, minimum: `1`). **Note: This is ignored if `scroll_acceleration.enabled` is set to `true`.**