Turn mouse reporting on by default in the main shell

Wheel/trackpad scroll only reaches OpenTUI when the terminal is
told to report it; otherwise the terminal's own alternate-scroll
mode resends it as arrow keys, which the prompt reads as history
navigation. Flipping the default lets routePromptWheelToTranscript
run for real scroll instead of only after Alt+M.

Trade accepted: this suppresses the terminal's native drag-select
in the main shell, which a separate ticket recorded wanting the
opposite default. Alt+M still hands the mouse back for drag-select
and copy. enableMouseMovement stays off; only clicks and wheel need
reporting.

Author: TheGreatAxios

src/tui-opentui/keybindings.ts

@@ -25,7 +25,7 @@ export const SHELL_SHORTCUTS: readonly ShellShortcut[] = [
   { keys: "Ctrl+C", description: "interrupt the run, or clear the prompt when idle; press twice to exit" },
   { keys: "Ctrl+O", description: "open the command palette; press again to close it" },
   { keys: "Alt+C", description: "copy mode: pick a message, tool output, or diff; press again to close it" },
-  { keys: "Alt+M", description: "take the mouse for click-to-expand and drag-scroll; off by default so drag-select and copy work" },
+  { keys: "Alt+M", description: "release the mouse to the terminal for native drag-select and copy; on by default for wheel scroll and click-to-expand" },
   { keys: "Alt+E", description: "expand or collapse every collapsible row (tool call, diff, skill, reasoning)" },
   { keys: "Tab", description: "move focus between the prompt and the transcript" },
   { keys: "Esc", description: "close the open overlay, or leave subagent observe" },

src/tui-opentui/palette.ts

@@ -171,7 +171,7 @@ export const DEFAULT_PALETTE_COMMANDS: readonly PaletteCommand[] = [
   },
   {
     id: "toggle_mouse",
-    label: "Toggle mouse capture (off by default so you can drag-select)",
+    label: "Toggle mouse capture (on by default; release it to drag-select)",
     keywords: ["mouse", "select", "selection", "copy", "drag"],
     dispatch: "residual",
     category: "view",

src/tui-opentui/product-host.ts

@@ -116,9 +116,10 @@ export type ProductHostConfig = {
   /** First-run telemetry disclosure, shown on the landing screen. */
   readonly telemetryNotice?: string
   /**
-   * Take DEC mouse reporting. Default false: while it is on the terminal hands
-   * drags to us and cannot select text, which breaks copy with the mouse.
-   * Alt+M flips it at runtime for click-to-expand and drag-scroll.
+   * Take DEC mouse reporting. Default true: wheel/trackpad scroll only
+   * reaches OpenTUI when the terminal is told to report it, otherwise the
+   * terminal's own alternate-scroll mode resends it as arrow keys. Alt+M
+   * hands the mouse back to the terminal for native drag-select.
    */
   readonly useMouse?: boolean
 }
@@ -206,11 +207,15 @@ export async function mountProductHost(
     : await createCliRenderer({
         exitOnCtrlC: false,
         targetFps: 30,
-        // Mouse reporting off by default: any of DEC 1000/1002/1003/1006 makes
-        // the terminal forward drags to us instead of selecting text, so the
-        // user cannot copy with the mouse. Alt+M takes the mouse when
-        // click-to-expand or drag-scroll is wanted.
-        useMouse: config.useMouse ?? false,
+        // Mouse reporting on by default: without it, wheel/trackpad scroll
+        // never reaches OpenTUI — the terminal's own alternate-scroll mode
+        // swallows it and resends it as arrow keys, which the prompt then
+        // reads as history navigation instead of the transcript scrolling.
+        // Cost accepted: this suppresses the terminal's native drag-select
+        // in the main shell. Alt+M hands the mouse back when that is wanted.
+        // enableMouseMovement stays off (no ?1003): only clicks and wheel
+        // are needed.
+        useMouse: config.useMouse ?? true,
         enableMouseMovement: false,
         // A plain terminal sends a bare CR for both Enter and Shift+Enter, so
         // the modifier only arrives once the kitty keyboard protocol is

src/tui-opentui/shell.ts

@@ -3999,8 +3999,8 @@ export function copyAllTargets(shell: AppShell): boolean {
 
 /**
  * Alt+M: take DEC mouse reporting, or hand it back to the terminal.
- * Reporting is off by default so drag-select and the terminal's own copy keep
- * working; taking it enables click-to-expand and drag-scroll at that cost.
+ * Reporting is on by default so wheel scroll and click-to-expand work;
+ * releasing it restores the terminal's own drag-select and copy.
  * Returns the new enabled state, or null when the host exposes no control.
  */
 export function toggleMouseCapture(shell: AppShell): boolean | null {